MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Journal of Orthopaedic Research' source. Thu, 09 Feb 2012 00:02:33 +0100 http://www.medworm.com/index.php?rid=5650923&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22060 AbstractPainful patellar crepitus is a potential complication in up to 14% of patients following posterior‐stabilized (PS) total knee arthroplasty (TKA). A recent clinical study identified influential patient and surgical variables by comparing a group of crepitus patients with controls matched for age, sex, and body mass index. The purpose of our study was to evaluate effects of variables identified as significant in the clinical study, including patellar ligament length, femoral component flexion, patellar button size, and position of the joint line, on contact between the quadriceps tendon and the PS femoral component. A previously verified finite element model was utilized to estimate tendo‐femoral contact during deep flexion activity. Using discrete perturbations, the computationa... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5650923 Fri, 03 Feb 2012 04:43:34 +0100 5650923 http://www.medworm.com/index.php?rid=5650926&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22076 AbstractBoth temporary and permanent orthopedic implants have, by default or design, surface chemistry, and topography. There is increasing evidence that controlling nanodisorder can result in increased osteogenesis. Block co‐polymer phase separation can be used to fabricate a nanotopography exhibiting a controlled level of disorder, both reproducibly and cost‐effectively. Two different topographies, produced through the use of block co‐polymer phase separation, were embossed onto the biodegradable thermoplastic, polycaprolactone (PCL). Analysis of the topography itself was undertaken with atomic force microscopy, and the topography's effect on human osteoblasts studied through the use of immunocytochemistry and fluorescence microscopy. Planar controls had a surface roughness 0.93 ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5650926 Tue, 31 Jan 2012 05:00:00 +0100 5650926 http://www.medworm.com/index.php?rid=5650925&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22081 AbstractInfections of percutaneous osseointegrated prostheses (POP) cause prolonged morbidity and device failure because once established, they are refractory to antibiotic therapy. To date, only limited translational animal studies have investigated the efficacy of POP designs in preventing infections. We developed an animal model to evaluate the efficacy of a porous‐coated titanium (Ti) subdermal barrier to achieve skin–implant integration and to prevent periprosthetic infection. In a single‐stage “amputation and implantation” surgery, 14 sheep were fitted with percutaneous devices with an attached porous‐coated Ti subdermal barrier. Nine sheep were implanted with a smooth Ti subdermal barrier construct and served as controls, with one control sheep removed from the study due... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5650925 Tue, 31 Jan 2012 05:00:00 +0100 5650925 http://www.medworm.com/index.php?rid=5650924&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22073 This study compares antioxidant capacity and lipid peroxidation using a novel model, in which rats were administered a selenium‐deficient diet for 4 weeks prior to their exposure to T‐2 toxin for 4 weeks. Changes in cell morphology and empty chondrocyte lacunae indicative of cell death, as well as cartilage proteoglycan loss in the deep zone of articular cartilage of knee joints were observed in rats with selenium‐deficient diet plus T‐2 toxin treatment. These changes were similar to those observed previously in KBD. The levels of thiobarbituric acid reactive substances (TBARS), indicative of lipid peroxidation in serum and cartilage, were significantly increased in all experimental groups compared to the normal diet group, while the levels of antioxidants, measured as total antiox... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5650924 Tue, 31 Jan 2012 05:00:00 +0100 5650924 http://www.medworm.com/index.php?rid=5639808&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22079 This study shows that miR‐210 is intensely expressed in ON, and might play a role in ON pathogenesis. The present study provides a solid basis for further functional analyses of miRNAs in ON. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5639808 Mon, 30 Jan 2012 05:50:19 +0100 5639808 http://www.medworm.com/index.php?rid=5639810&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22077 AbstractThe first clinical sign of ceramic hip prosthesis failure is hip noise. We therefore investigated whether isolation, observation at scanning electron microscopy, and chemical identification with microanalysis of particles from synovial fluid of “noisy hip” could be predictive of ceramic damage. Firstly, the level of “physiological wear” of well functioning ceramic‐on‐ceramic hip prostheses was assessed with this method, then the test was validated as diagnostic method for liner fracture. Twelve asymptomatic patients were enrolled to demonstrate the first aim; 39 cases of noisy hip (GROUP 1), and 7 cases of pending failure not related to ceramic (GROUP 2) were enrolled for the second aim. The analysis of the synovial fluid of the 12 asymptomatic patients allowed to set t... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5639810 Fri, 27 Jan 2012 05:00:00 +0100 5639810 http://www.medworm.com/index.php?rid=5630884&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22070 In conclusion, we have developed a robust method for isolation and expansion of rabbit MSCs by combining low‐density with hypoxic culture, which can be applied for the design of clinical trials in allogeneic transplantation of MSCs for bone healing. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5630884 Fri, 27 Jan 2012 04:49:31 +0100 5630884 http://www.medworm.com/index.php?rid=5630885&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22075 In this study, we investigated the relationship between AIS and polymorphisms in MATN‐1, LCT C/T‐13910, and VDR BsmI genes. 53 Turkish adolescents with diagnosed AIS and 54 healthy adult individuals were included in the study. MATN‐1, LCT C/T‐13910, and VDR BsmI gene mutations were analyzed with real‐time PCR. We did not detect a statistically significant difference between AIS and control groups in respect to those three different gene polymorphisms (p < 0.05). We next evaluated the associations of all three SNPs with scoliosis curve severity. There was no significant difference between curve severity and gene polymorphisms (p < 0.05). In terms of gene polymorphisms, AIS patients with a family history of AIS did not significantly differ from AIS patients who did no... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5630885 Wed, 25 Jan 2012 05:00:00 +0100 5630885 http://www.medworm.com/index.php?rid=5621563&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22078 This study investigated whether the synthetic peptide B2A (B2A2‐K‐NS) could induce in vitro chondrogenic differentiation and enhance the in vivo repair of damaged cartilage in an osteoarthritis model. In vitro, micromass cultures of murine and human stem cells with and without B2A were used as models of chondrogenic differentiation. Micromasses were evaluated for gene expression using microarray analysis and quantitative PCR; and for extracellular matrix production by Alcian blue staining for sulfated glycosaminoglycan and immunochemical detection of collagen type II. In vivo, osteoarthritis was chemically induced in knees of adult rats by an injection of mono‐iodoacetate (MIA) into the synovial space. Treatment was administered at 7‐ and 14 days after the MIA by injection into the... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5621563 Tue, 24 Jan 2012 04:36:28 +0100 5621563 http://www.medworm.com/index.php?rid=5611842&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22056 AbstractSeveral potential advantages exist for cementless tibial fixation including preservation of bone stock and increased longevity of fixation. However, clinical results have been variable, with reports of extensive radiolucent lines, rapid early migration, and aseptic loosening. The primary stability of an implant depends on the micromotion of the bone–implant interface, which depends on the kinematics and kinetics of the replaced joint. Finite element analysis was used to examine the micromotion for different activities (walking, stair ascent, stair descent, stand‐to‐sit, and deep knee bend) for three commercially available tibial tray designs. Similar trends were observed for all three designs across the range of activities. Stair ascent and descent generated the highest micro... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5611842 Sat, 21 Jan 2012 04:15:48 +0100 5611842 http://www.medworm.com/index.php?rid=5611843&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22068 AbstractAbdominal wall muscles have a unique morphology suggesting a complex role in generating and transferring force to the spinal column. Studying passive mechanical properties of these muscles may provide insights into their ability to transfer force among structures. Biopsies from rectus abdominis (RA), external oblique (EO), internal oblique (IO), and transverse abdominis (TrA) were harvested from male Sprague–Dawley rats, and single muscle fibers and fiber bundles (4–8 fibers ensheathed in their connective tissue matrix) were isolated and mechanically stretched in a passive state. Slack sarcomere lengths were measured and elastic moduli were calculated from stress–strain data. Titin molecular mass was also measured from single muscle fibers. No significant differences were fou... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5611843 Fri, 20 Jan 2012 05:00:00 +0100 5611843 http://www.medworm.com/index.php?rid=5599825&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22062 This study demonstrated a successful application of computational morphometry in bone. The detected anatomical differences may lead to a larger moment arm generated via the medial branch of the suspensory apparatus, increasing pressure on the sesamoid surface, and thus potentially predisposing to fracture. Findings from this pilot study not only increase the likelihood of accurate PSB fracture risk assessment, but also shed light on investigating the influence of sports and exercise on human athletes. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5599825 Wed, 18 Jan 2012 05:15:18 +0100 5599825 http://www.medworm.com/index.php?rid=5585415&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22063 This study aimed to evaluate the association of the SNP by a large‐scale replication study. A total of 8,457 subjects (3,129 OA cases and 5,328 controls) from seven independent cohorts from six countries (Japan, China, Taiwan, Korea, Greece, and Australia) were recruited and genotyped. The association of rs17039192 with knee OA was evaluated by meta‐analyses. The association of the HIF‐2α SNP was not replicated in any of the populations. Contrary to the previous report, the odds ratios (ORs) of the risk allele frequency were all less than 1. A combined analysis for the seven populations also showed no replication of the association (OR = 0.91, 95% confidence interval = 0.81–1.03). Our large‐scale meta‐analysis showed that the association of rs17039192 in HIF‐2α with... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5585415 Sat, 14 Jan 2012 14:26:47 +0100 5585415 http://www.medworm.com/index.php?rid=5585420&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22048 AbstractPolymethylmethacrylate (PMMA) is the most commonly used bone void filler for vertebral augmentation in osteoporotic fracture. It provides mechanical stability and immediate pain relief; however, PMMA is not osteointegrated and is separated from the surrounding bone tissue by a thin fibrous layer. The aim of this study was to investigate the effect of nanocrystalline hydroxyapatite (HA) on osteointegration of PMMA in a sheep model. A composite material, consisting of PMMA and nanocrystalline HA (70:30, v/v), was implanted in one distal femur, with pure PMMA in the other femur as a control. Three and 6 months after implantation, the distal femora were histologically investigated. All composite implants exhibited a tight junction to the surrounding bone tissue, with minimal bone ingro... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5585420 Fri, 13 Jan 2012 05:00:00 +0100 5585420 http://www.medworm.com/index.php?rid=5585419&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22047 AbstractA layer of cells (the “biomembrane”) has been identified in large segmental defects between bone and surgically placed methacrylate spacers or antibiotic‐impregnated cement beads. We hypothesize that this contains a pluripotent stem cell population with potential valuable applications in orthopedic tissue engineering. Objectives using biomembranes harvested from rat segmental defects were to: (1) Culture biomembrane cells in specialized media to direct progenitor cells along bone or cartilage cell differentiation lineages; (2) evaluate harvested biomembranes for mesenchymal stem cell markers, and (3) define relevant gene expression patterns in harvested biomembranes using microarray analysis. Culture in osteogenic media produced mineralized nodules; culture in chondrogenic me... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5585419 Fri, 13 Jan 2012 05:00:00 +0100 5585419 http://www.medworm.com/index.php?rid=5585418&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22067 AbstractSeveral biomarkers have been used to evaluate osteoarthritis of the limb joints. Here we evaluated the use of serum cartilage metabolites as biomarkers for degenerative lumbar scoliosis (DLS). Fifty‐two DLS patients with Cobb angle > 10° were compared with 19 control patients. Serum levels of hyaluronic acid (HA), keratan sulfate (KS), cartilage oligomeric matrix protein (COMP), collagen type II cleavage (C2C), and procollagen type II C‐propeptide (CPII) were measured. Serum levels of KS (DLS 1.20 ± 0.44 µg/ml vs. control 0.98 ± 0.33 µg/ml), CPII (DLS 1905.1 ± 948.2 ng/ml vs. control 1223.6 ± 884.4 ng/ml), and C2C (DLS 219.1 ± 59.2 ng/ml vs. control 177.7 ± 71.7 ng/ml) were significantly higher in DLS. There were no significan... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5585418 Fri, 13 Jan 2012 05:00:00 +0100 5585418 http://www.medworm.com/index.php?rid=5585417&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22069 AbstractThe roles of ADAMTS‐7 and ADAMTS‐12 in disc degeneration have not been previously examined. The purpose of this study was to examine the expression of ADAMTS‐7 and ADAMTS‐12 in the endplate cells isolated from patients with degenerative disc disease and to see whether they are associated with the pathological change of endplate. Sixty‐four degenerated lumbar endplate specimens were obtained from the patients with degenerative disc disease categorized as type Modic I or II in magnetic resonance imaging (MRI) and 12 nondegenerative specimens as control (vertebra burst fracture patients without degenerative change in MRI) during surgical procedures. The expression of ADAMTS‐7 and ADAMTS‐12 was examined by real‐time PCR and Western blotting. A statistically significant ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5585417 Fri, 13 Jan 2012 05:00:00 +0100 5585417 http://www.medworm.com/index.php?rid=5585416&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22071 This study investigates the in vivo effect of PAR‐2 deletion on fracture healing by assessing differences between wild‐type (PAR‐2+/+) and knock‐out (PAR‐2−/−) mice. Unilateral mid‐shaft femur fractures were created in 34 PAR‐2+/+ and 28 PAR‐2−/− mice after intramedullary fixation. Histologic assessments were made at 1, 2, and 4 weeks post‐fracture (wpf), and radiographic (plain radiographs, micro‐computed tomography (µCT)) and biomechanical (torsion testing) assessments were made at 7 and 10 wpf. Both the fractured and un‐fractured contralateral femur specimens were evaluated. Polar moment of inertia (pMOI), tissue mineral density (TMD), bone volume fraction (BV/TV) were determined from µCT images, and callus diameter was determined from plain radiographs. ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5585416 Fri, 13 Jan 2012 05:00:00 +0100 5585416 http://www.medworm.com/index.php?rid=5585423&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22066 AbstractThe hypothalamus is of critical importance in regulating bone remodeling. This is underscored by the fact that intracerebroventricular‐application of leptin in ewe leads to osteopenia. As a large animal model of osteoporosis, this approach has some limitations, such as high technical expenditure and running costs. Therefore we asked if a surgical ablation of the leptin signaling axis would have the same effects and would thereby be a more useful model. We analyzed the bone phenotype of ewe after surgical hypothalamo‐pituitary disconnection (HPD + OVX) as compared to control ewe (OVX) after 3 and 12 months. Analyses included histomorphometric characterization, micro‐CT and measurement of bone turnover parameters. Already 3 months after HPD we found osteopenic ewe with a si... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5585423 Tue, 10 Jan 2012 05:00:00 +0100 5585423 http://www.medworm.com/index.php?rid=5585422&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22072 In conclusion, pedicle screws with a bioactive surface treated by MAO can improve screw fixation strength in osteoporotic spines in sheep. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5585422 Tue, 10 Jan 2012 05:00:00 +0100 5585422 http://www.medworm.com/index.php?rid=5585421&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22074 We examined the rotary motions of two distinct cementless surface replacement arthroplasties of the shoulder that were implanted on humeri with central spherical bone defects of 8%, 17%, and 37% of the head volume (n = 5 each). Rotary motions were measured under a cyclic torque application and translated into relative micromotions. Implant A with a perforated central crown had micromotions < 150 µm in all bony defects and during all simulated shoulder activities. Implant B with a central tapered tri‐fin pin had no micromotions > 150 µm in defects of 0% and 8% during a strenuous activity like lifting 10 kg, but did exhibit micromotion > 150 µm in 40% of the experiments in defects of 17% and 37%, which could impair bony ingrowth. Implant B displayed a si... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5585421 Tue, 10 Jan 2012 05:00:00 +0100 5585421 http://www.medworm.com/index.php?rid=5585424&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22064 AbstractSplinting and nerve and tendon gliding exercises are commonly used to treat carpal tunnel syndrome (CTS). It has been postulated that both modalities reduce intraneural edema. To test this hypothesis, 20 patients with mild to moderate CTS were randomly allocated to either night splinting or a home program of nerve and tendon gliding exercises. Magnetic resonance images of the wrist were taken at baseline, immediately after 10 min of splinting or exercise, and following 1 week of intervention. Primary outcome measures were signal intensity of the median nerve at the wrist as a measure of intraneural edema and palmar bowing of the carpal ligament. Secondary outcome measures were changes in symptom severity and function. Following 1 week of intervention, but not immediately after 10... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5585424 Mon, 09 Jan 2012 05:00:00 +0100 5585424 http://www.medworm.com/index.php?rid=5573386&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22065 In this study we evaluated the Minimum Biofilm Eradication Concentration‐High Throughput Plates (MBEC™‐HTP) as biofilm in vitro model for studies of implant associated infections. Staphylococcus aureus and Staphylococcus epidermidis biofilms were grown on MBEC™‐HTP. To ensure the biofilm formation, antibiotic susceptibility tests and scanning electron microscopy (SEM) was carried out. Susceptibility tests were carried out using gentamicin, vancomycin, rifampicin, fosfomycin, clindamycin, and linezolid. Colony forming units counting were carried out. Minimal inhibitory concentration (MIC) and biofilm inhibitory concentration (BIC) were estimated. The CFU counting showed potency of rifampicin and daptomycin against S. epidermidis biofilms and rifampicin against S. aureus biofilms. ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5573386 Mon, 09 Jan 2012 04:34:35 +0100 5573386 http://www.medworm.com/index.php?rid=5573392&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22059 In this study, we used number of applied cycles and initial (day‐0) parameters that are indicative of induced damage to assess the molecular response 7 days after fatigue loading. We hypothesized that day‐0 hysteresis, elongation, and stiffness of the loading and unloading load–displacement curves would be predictive of the 7‐day molecular response. Results showed correlations between the 7‐day molecular response and both day‐0 elongation and unloading stiffness. Additionally, loading resulted in upregulation of several extracellular matrix genes that suggest adaptation; however, several of these genes (Col‐I, ‐XII, MMP 2, and TIMP 3) shut down after a high level of damage was induced. We showed that evaluating the 7‐day molecular profile in light of day‐0 elongation pr... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5573392 Fri, 06 Jan 2012 05:00:00 +0100 5573392 http://www.medworm.com/index.php?rid=5573391&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22058 AbstractPrevious research employing indirect measures of arch structure, such as those derived from footprints, have indicated that obesity results in a “flatter” foot type. In the absence of radiographic measures, however, definitive conclusions regarding the osseous alignment of the foot cannot be made. We determined the effect of body mass index (BMI) on radiographic and footprint‐based measures of arch structure. The research was a cross‐sectional study in which radiographic and footprint‐based measures of foot structure were made in 30 subjects (10 males, 20 female) in addition to standard anthropometric measures of height, weight, and BMI. Multiple (univariate) regression analysis demonstrated that both BMI (β = 0.39, t26 = 2.12, p = 0.04) and radiographic arch... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5573391 Fri, 06 Jan 2012 05:00:00 +0100 5573391 http://www.medworm.com/index.php?rid=5573390&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22026 AbstractLittle is known whether trabecular bone matrix mineralization is altered at the site of osteoporotic vertebral fractures. Bone mineralization density distribution (BMDD) was assessed in trabecular bone of acute, single‐level compression fractures of the spine at various stages of fracture repair using quantitative backscattered electron imaging (qBEI). The grading of the repair stage was performed by histological methods. From 20 patients, who underwent either kyphoplasty (n = 18) or vertebroplasty (n = 2), a vertebral bone biopsy was taken prior to cement augmentation. Six patients took bisphosphonates (BP) prior to fracture. Three study groups were formed: N1 = early‐, N2 = late‐healing and B = BP treatment at late healing stage. In general, all groups h... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5573390 Fri, 06 Jan 2012 05:00:00 +0100 5573390 http://www.medworm.com/index.php?rid=5573389&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22028 The objective of the current study was to determine if transplantation of mesenchymal stromal cells (MSC) from a healthy, young donor mouse into an osteopenic recipient mouse could enhance osseointegration of a femoral implant. MSC harvested from normal young adult mice differentiated into bone forming osteoblasts when cultured on implant grade titanium surfaces ex vivo and promoted bone formation around titanium‐coated rods implanted in the femoral canal of osteopenic recipient mice. Micro computed tomographic imaging and histological analyses showed more, better quality, bone in the femur that received the MSC transplant compared with the contra‐lateral control femur that received carrier alone. These results provide pre‐clinical evidence that MSC transplantation promotes peri‐im... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5573389 Fri, 06 Jan 2012 05:00:00 +0100 5573389 http://www.medworm.com/index.php?rid=5573388&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22057 This study has shown that patient characteristics do effect cell proliferation rate and cell surface characterization, but as seeding density has a significant relationship with proliferation rate, it can be altered, possibly along with other cell culturing strategies, to compensate for the effects of patient factors on MSCs. We have also shown that gender affects cell proliferation and cell surface characterization, something most previous studies may have failed to identify as they group male and female patients together. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5573388 Fri, 06 Jan 2012 05:00:00 +0100 5573388 http://www.medworm.com/index.php?rid=5573387&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22061 AbstractThe pathophysiology of paradoxical elbow flexion contractures following neonatal brachial plexus injury (NBPI) is incompletely understood. The current study tests the hypothesis that this contracture occurs by denervation‐induced impairment of elbow flexor muscle growth. Unilateral forelimb paralysis was created in mice in four neonatal (5‐day‐old) BPI groups (C5‐6 excision, C5‐6 neurotomy, C5‐6 neurotomy/repair, and C5‐T1 global excision), one non‐neonatal BPI group (28‐day‐old C5‐6 excision), and two neonatal muscle imbalance groups (triceps tenotomy ± C5‐6 excision). Four weeks post‐operatively, motor function, elbow range of motion, and biceps/brachialis functional lengths were assessed. Musculocutaneous nerve (MCN) denervation and reinnervation w... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5573387 Fri, 06 Jan 2012 05:00:00 +0100 5573387 http://www.medworm.com/index.php?rid=5562617&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22052 AbstractThe ability of uncemented femoral stems to osseointegrate properly depends largely on their fit in the proximal femur. We evaluated the topography of the proximal femur and determined differences based on age and sex. Retrospectively, anteroposterior radiographs from 312 (168 male, 144 female) pre‐operative total hip arthroplasty (THA) patients (age of 21–85 years) were collected. Radiographic measurements were taken at 10 mm intervals along the length of the femur. Variables including canal flare index (CFI) and cortical index (CI) were calculated. Data were binned into three age groups and separated by sex for comparison. Measurements showed that CFI decreased with age for both sexes; however, females demonstrated a greater decrease. Decrease in flare occurred primarily on ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5562617 Fri, 06 Jan 2012 04:20:53 +0100 5562617 http://www.medworm.com/index.php?rid=5562621&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22049 AbstractMinipigs are a recommended large animal model for preclinical testing of human orthopedic implants. Mesenchymal stem cells (MSCs) are the key repair cells in bone healing and implant osseointegration, but the osteogenic capacity of minipig MSCs is incompletely known. The aim of this study was to isolate and characterize minipig bone marrow (BM) and peripheral blood (PB) MSCs in comparison to human BM‐MSCs. BM sample was aspirated from posterior iliac crest of five male Göttingen minipigs (age 15 ± 1 months). PB sample was drawn for isolation of circulating MSCs. MSCs were selected by plastic‐adherence as originally described by Friedenstein. Cell morphology, colony formation, proliferation, surface marker expression, and differentiation were examined. Human BM‐MSCs were... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5562621 Tue, 03 Jan 2012 05:00:00 +0100 5562621 http://www.medworm.com/index.php?rid=5562620&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22055 In this study, a dynamic finite element model of an implanted PF joint was applied in conjunction with a probabilistic simulation to establish relationships between alignment parameters and PF kinematics, contact mechanics, and internal stresses. Both traditional sensitivity analysis and a coupled probabilistic and principal component analysis approach were applied to characterize relationships between implant alignment and resulting joint mechanics. Critical alignment parameters, and combinations of parameters, affecting PF mechanics were identified for three patellar designs (dome, modified dome, and anatomic). Femoral internal–external (I‐E) alignment was identified as a critical alignment factor for all component designs, influencing medial–lateral contact force and anterior–po... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5562620 Tue, 03 Jan 2012 05:00:00 +0100 5562620 http://www.medworm.com/index.php?rid=5562619&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22046 In this study, we evaluated the role of SATB2 in oxidative stress‐induced apoptotic insults to human osteoblast‐like MG63 cells and mouse MC3T3‐E1 cells. Exposure of MG63 cells to menadione increased intracellular reactive oxygen species levels in a concentration‐ and time‐dependent manner. Simultaneously, menadione‐induced oxidative stress triggered cell shrinkage and decreased cell viability. In addition, treatment of MG63 cells with menadione time‐dependently decreased the mitochondrial membrane potential but enhanced caspase‐3 activity. As a result, menadione‐induced DNA fragmentation and cell apoptosis. As to the mechanism, exposure of MG63 cells to menadione amplified SATB2 messenger (m)RNA and protein expression in a time‐dependent manner. Knockdown of translatio... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5562619 Tue, 03 Jan 2012 05:00:00 +0100 5562619 http://www.medworm.com/index.php?rid=5562618&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22054 AbstractIncreased oxidative stress is currently considered as a crucial cause of corticosteroid‐induced osteonecrosis. The aim of this study was to evaluate the effect of fullerol, a powerful antioxidant, on adipogenic and osteogenic differentiation of a mouse bone marrow derived multipotent cell line, D1. Upon treatment with dexamethasone, D1 cells containing lipid vesicles were distinguishable from the surrounding cells by Oil Red O staining at day 21. Simultaneous treatment of dexamethasone with antioxidant glutathione or fullerol decreased the number of cells containing lipid vesicles. Treatment with dexamethasone for 7 days resulted in a significant increase in adipogenic markers peroxisome proliferator‐activated receptor gamma and adipocyte protein 2 gene expression and decrease ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5562618 Tue, 03 Jan 2012 05:00:00 +0100 5562618 http://www.medworm.com/index.php?rid=5553689&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22041 In this study, a scaled musculoskeletal model was used to extract a full set of muscle and hip joint loads occurring during a walking cycle. These loads were applied incrementally to an FE model to analyze micromotions. The relation between micromotions and external loads was investigated, and how micromotions during a full loading cycle compared to those calculated when applying a peak load only. Finally, the effect of external constraints was analyzed (full model vs. diaphyseal fixation and reduced number of muscle loads). Relatively large micromotions were found during the swing phase when the hip joint forces were relatively low. Maximal micromotions, however, did concur with the peak hip joint force. Applying only a peak joint force resulted in peak micromotions similar to those found... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5553689 Sun, 01 Jan 2012 04:14:22 +0100 5553689 http://www.medworm.com/index.php?rid=5553692&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22045 This study aims to apply image registration to calculate strain distributions in metastatically involved rodent vertebrae utilizing µCT imaging. Osteolytic vertebral lesions were developed in five rnu/rnu rats 2–3 weeks post intracardiac injection with MT‐1 human breast cancer cells. An image registration algorithm was used to calculate and compare strain fields due to axial compressive loading in metastatically involved and control vertebrae. Tumor‐bearing vertebrae had greatly increased compressive strains, double the magnitude of strain compared to control vertebrae (p = 0.01). Qualitatively strain concentrated within the growth plates in both tumor bearing and control vertebrae. Most interesting was the presence of strain concentrations at the dorsal wall in metastatically i... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5553692 Fri, 30 Dec 2011 05:00:00 +0100 5553692 http://www.medworm.com/index.php?rid=5553691&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22051 AbstractAdaptive muscle activation strategies following a massive rotator cuff tear (MRCT) are inadequately understood, and the relationship among muscles during everyday activities has not been considered. Thirteen healthy subjects comprised the control group, and 11 subjects with a MRCT the patient group. Upper limb function was assessed using the Functional Impairment test‐hand, neck, shoulder, and arm (FIT‐HaNSA). Electromyography (EMG) was recorded from 13 shoulder muscles, comprising five muscle groups, during a shelf‐lifting task. Mean FIT‐HaNSA scores were significantly lower in MRCT patients (p ≤ 0.001), reflecting a severe functional deficit. In MRCT patients, EMG signal amplitude was significantly higher for the biceps brachii‐brachioradialis (p < 0.001), ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5553691 Fri, 30 Dec 2011 05:00:00 +0100 5553691 http://www.medworm.com/index.php?rid=5553690&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22040 AbstractOur objectives were to determine cartilage contact stress during walking, stair climbing, and descending stairs in a well‐defined group of normal volunteers and to assess variations in contact stress and area among subjects and across loading scenarios. Ten volunteers without history of hip pain or disease with normal lateral center‐edge angle and acetabular index were selected. Computed tomography imaging with contrast was performed on one hip. Bone and cartilage surfaces were segmented from volumetric image data, and subject‐specific finite element models were constructed and analyzed using a validated protocol. Acetabular contact stress and area were determined for seven activities. Peak stress ranged from 7.52 ± 2.11 MPa for heel‐strike during walking (233% BW) t... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5553690 Fri, 30 Dec 2011 05:00:00 +0100 5553690 http://www.medworm.com/index.php?rid=5553694&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22025 AbstractThe purpose of this study is to determine the role of ERK5 in cellular invasion of osteosarcoma (OS). The human OS cell line (MG63, SaOS, and U2OS) and primary OS cells were used for the study. The expression of ERK5 and MMP‐9 in each cell was examined by western blot or RT‐PCR. To evaluate the biological role of ERK5, proliferation assay (MTT) and invasion assay (BD Matrigel™) were performed after silencing ERK5 using siRNA. MMPs expressions were analyzed using RT‐PCR and zymography after silencing ERK5. ERK5 was distinctly overexpressed in U2OS and primary OS cell. Both of them also expressed MMP‐9, which was not shown in MG63 and SaOS in RT‐PCR. ERK5 silencing did not suppress the proliferation of OS cells. However, ERK5 silencing significantly reduced the number of ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5553694 Thu, 29 Dec 2011 05:00:00 +0100 5553694 http://www.medworm.com/index.php?rid=5553693&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22050 AbstractSynovial sarcomas (SS) are soft tissue sarcomas with poor prognosis, displaying a lack of response to conventional cytotoxic chemotherapy. Although SS cell lines have moderate chemosensitivity to isofamide and doxorubicin therapy, the clinical prognosis is still poor. In this article, we showed that flavokawain B (FKB), a novel chalcone from kava extract, potently inhibits the growth of SS cell lines SYO‐I and HS‐SY‐II through induction of apoptosis. Treatment with FKB increased caspase 8, 9, and 3/7 activity compared to vehicle‐treated controls, indicating that both extrinsic and intrinsic apoptotic pathways were activated. Furthermore, FKB treatment of both cell lines resulted in increased mRNA and protein expression of death receptor‐5 and the mitochondrial pro‐apopt... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5553693 Thu, 29 Dec 2011 05:00:00 +0100 5553693 http://www.medworm.com/index.php?rid=5545995&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22038 This study confirms the in vivo osteogenic properties of genetically modified muscle and suggests novel strategies for healing bone. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5545995 Wed, 28 Dec 2011 20:50:39 +0100 5545995 http://www.medworm.com/index.php?rid=5545996&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22044 AbstractCalcium phosphate cement (CPC) is reported to have excellent biocompatibility and osteoconductivity. However, its biodegradability must be improved to promote bone regeneration. We have mixed gelatin powder with CPC to create a composite containing macropores with interconnectivity. Sixty rabbits were grouped as follows: 85wt% CPC to 15wt% gelatin powder (C15), 90wt% CPC to 10wt% gelatin powder (C10), 100wt% CPC (C0) as control group and Sham group. Trabecular bone defects of distal femurs were made and implanted with the composites. The femurs were harvested for histomorphometry at 4, 12, 24 weeks after implantation, and mechanical testing at 3 days, 1, 4, 12, 24 weeks. Compared with C0, X‐ray and micro‐CT results of the composites revealed a progressive increase in the amount... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5545996 Tue, 27 Dec 2011 05:00:00 +0100 5545996 http://www.medworm.com/index.php?rid=5516587&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22043 In this study, the goat knee extensor mechanism (quadriceps tendon, patella, and patellar tendon) was removed from the right hind limb in 16 goats. The device connected the quadriceps muscle to a stainless steel bone plate on the tibia. Mechanical testing and histology specimens were collected from each operated leg and contralateral unoperated control legs at 180 days. Maximum forces in the operated leg (vs. unoperated) were 1,400 ± 93 N (vs. 1,179 ± 61 N), linear stiffnesses were 33 ± 3 N/mm (vs. 37 ± 4 N/mm), and elongations at failure were 92.1 ± 5.3 mm (vs. 68.4 ± 3.8 mm; mean ± SEM). Higher maximum forces (p = 0.02) and elongations at failure (p = 0.008) of legs with the device versus unoperated controls were significant; linear ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5516587 Mon, 19 Dec 2011 16:41:39 +0100 5516587 http://www.medworm.com/index.php?rid=5507213&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22024 (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5507213 Fri, 16 Dec 2011 17:01:41 +0100 5507213 http://www.medworm.com/index.php?rid=5516590&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22035 AbstractRetrieved hip resurfacing arthroplasties (HRA) revised for causes other than osteonecrosis enable further insights into bone–cement interactions within the interface with only minimal biomechanical stresses. Our primary objective was to investigate the mineralization changes at the trabecular bone interface in retrieved hips using bright field and polarized light microscopy and by quantitative backscattered electron imaging. Because superficial seams of non‐mineralized bone tissue varied substantially, we defined hyperosteoidosis as an osteoid seam of more than 20 µm thickness. We hypothesized that interface hyperosteoidosis might be caused by the demineralization of previously mineralized bone tissue. One hundred and thirty‐one retrieved HRAs with viable bone remnant tiss... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5516590 Fri, 16 Dec 2011 05:00:00 +0100 5516590 http://www.medworm.com/index.php?rid=5516589&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22036 AbstractGene transfer is a promising approach to the delivery of chondrotrophic growth factors to promote cartilage repair. It is unlikely that a single growth factor transgene will optimally regulate these cells. The aim of this study was to identify those growth factor transgene combinations that optimally regulate aggrecan, collagen type II and collagen type I gene expression by articular chondrocytes. We delivered combinations of the transgenes encoding fibroblast growth factor‐2, insulin‐like growth factor I, transforming growth factor beta1, bone morphogenetic protein‐2, and/or bone morphogenetic protein‐7 and assessed chondrocyte responses by measuring changes in the expression of aggrecan, type II collagen and type I collagen genes. These growth factor transgenes differenti... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5516589 Fri, 16 Dec 2011 05:00:00 +0100 5516589 http://www.medworm.com/index.php?rid=5516588&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22037 AbstractThe study aim was to address the need for objective markers of pain‐modifying interventions by testing the hypothesis that selective gait measures of knee joint loading can distinguish differences between non‐steroidal anti‐inflammatory (NSAID), analgesic treatment (opioid‐receptor agonist), and placebo in patients medial knee osteoarthritis (OA). A randomized, single‐blind washout, double‐blind treatment, double‐dummy cross‐over trial using three treatment arms placebo, opioid (Oxycodone), and NSAID (Celecoxib) in medial compartment knee OA patients. Six patients with Kellgren–Lawrence radiographic severity grades of 2 or 3 completed six testing sessions (gait and pain assessment) at 2‐week intervals. A significant increase was found in the knee total reaction ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5516588 Fri, 16 Dec 2011 05:00:00 +0100 5516588 http://www.medworm.com/index.php?rid=5507215&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22053 (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5507215 Wed, 14 Dec 2011 05:00:00 +0100 5507215 http://www.medworm.com/index.php?rid=5507214&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22042 In this study, we investigated the effects of functional loading on repair of critically sized segmental bone defects. About 6‐mm defects were created in rat femora, and each defect received 5 µg recombinant human bone morphogenetic protein‐2 (rhBMP‐2), delivered in alginate hydrogel. Limbs were stabilized by either stiff fixation plates for the duration of the study or compliant plates that allowed transfer of compressive ambulatory loads beginning at week 4. Healing was assessed by digital radiography, microcomputed tomography, mechanical testing, histology, and finite element modeling. Loading significantly increased regenerate bone volume and average polar moment of inertia. The response to loading was location‐dependent with the polar moment of inertia increased at the prox... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5507214 Wed, 14 Dec 2011 05:00:00 +0100 5507214 http://www.medworm.com/index.php?rid=5496675&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22033 AbstractInjured rat Achilles tendons were treated with botulism toxin to create a mechanically unloaded condition (unloaded) or left untreated (loaded), and then treated with phosphate‐buffered saline (PBS), platelet‐rich plasma (PRP), tendon stem cells (TSCs), or a combination (TSCs + PRP). mRNA and protein expression of collagen I, collagen III, tenascin C, and Smad 8 were determined by real time PCR and immunostaining, respectively. Loaded tendons treated with PBS, PRP, or TSCs for 3 or 14 days had higher collagen I mRNA expression than unloaded tendons. Loaded tendons treated with PBS for 3 or 14 days or with PRP for 3 days had higher collagen I protein levels than unloaded tendons. Loaded tendons treated for 3 days with PBS, for 14 days with PRP or TSCs or TSCs + PRP for 3... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5496675 Tue, 13 Dec 2011 17:29:34 +0100 5496675 http://www.medworm.com/index.php?rid=5496677&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22023 AbstractImpairment of the human neuromusculoskeletal system can lead to significant mobility limitations and decreased quality of life. Computational models that accurately represent the musculoskeletal systems of individual patients could be used to explore different treatment options and optimize clinical outcome. The most significant barrier to model‐based treatment design is validation of model‐based estimates of in vivo contact and muscle forces. This paper introduces an annual “Grand Challenge Competition to Predict In Vivo Knee Loads” based on a series of comprehensive publicly available in vivo data sets for evaluating musculoskeletal model predictions of contact and muscle forces in the knee. The data sets come from patients implanted with force‐measuring tibial prosthes... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5496677 Mon, 12 Dec 2011 05:00:00 +0100 5496677 http://www.medworm.com/index.php?rid=5496676&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22032 AbstractThe effect of a valgus knee brace and a lateral wedged insole on knee and ankle kinematics and kinetics was evaluated in ten patients with medial knee osteoarthritis (OA). The knee orthosis was tested in two valgus adjustments (4° and 8°), and the laterally wedged insole was fabricated with an inclination of 4°. A motion capture system and force platforms were used for data collection and joint moments were calculated using inverse dynamics. The valgus moment applied by the orthosis was also measured using a strain gauge implemented in the orthosis' rotational axis. For the second peak knee adduction moment, decreases of 18%, 21%, and 7% were observed between baseline and test conditions for the orthosis in 4° valgus, in 8° valgus, and insole, respectively. Similar decreases w... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5496676 Mon, 12 Dec 2011 05:00:00 +0100 5496676 http://www.medworm.com/index.php?rid=5488917&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22039 AbstractAn ultrasonometric and computed‐tomographic study of bone healing was undertaken using a model of a transverse mid‐shaft osteotomy of sheep tibiae fixed with a semi‐flexible external fixator. Fourteen sheep were operated and divided into two groups of seven according to osteotomy type, either regular or by segmental resection. The animals were killed on the 90th postoperative day and the tibiae resected for the in vitro direct contact transverse and axial measurement of ultrasound propagation velocity (UV) followed by quantitative computer‐aided tomography (callus density and volume) through the osteotomy site. The intact left tibiae were used for control, being examined in a symmetrical diaphyseal segment. Regular osteotomies healed with a smaller and more mature callus th... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5488917 Sat, 10 Dec 2011 17:41:10 +0100 5488917 http://www.medworm.com/index.php?rid=5488918&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22030 In this study, we evaluated the effect of atorvastatin calcium on the flexural properties (3‐point bending strength and modulus) of corticosteroid (methylprednisolone acetate) treated rabbit femurs and tibias. Our study hypothesis was that the use of statins would counteract the loss of bone strength caused by corticosteroid treatment. The 40 rabbits were divided into 5 groups: control, corticosteroid alone and corticosteroid combined with oral doses of atorvastatin calcium (2, 10, or 20 mg/day). A daily oral dose of atorvastatin calcium treatment for 70 days weakened the long bones of methylprednisolone acetate treated rabbits irrespective of the dosage (2, 10, or 20 mg). Cortical bone strength was assessed using the 3‐point bending test at the end of the study period. A daily ora... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5488918 Thu, 08 Dec 2011 05:00:00 +0100 5488918 http://www.medworm.com/index.php?rid=5478593&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22034 AbstractAlthough osteosarcoma is the most common bone malignancy, the molecular and cellular mechanisms influencing its pathogenesis have remained elusive. Prion proteins (PRNP and PRND), known mostly for its involvement in neurodegenerative spongiform encephalopathies, have been recently demonstrated to be involved in resistance to apoptosis, tumorigenesis, proliferation, and metastasis. The main aim of research was to study whether prion proteins were over‐expressed in human osteosarcoma, and if prion proteins could have a role also in osteosarcomas. We evaluated differential gene expression between 22 cases of osteosarcoma and 40 cases of normal bone specimens through cDNA microarray analysis spanning a substantial fraction of the human genome. PRNP and PRND are significantly over‐e... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5478593 Wed, 07 Dec 2011 17:09:39 +0100 5478593 http://www.medworm.com/index.php?rid=5488919&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22031 This study provides support for a relationship between the mechanical response of cartilage to physiological loading (cartilage‐on‐cartilage contact area and cartilage deformation) and MR relaxation times (T1ρ and T2) in both OA patients and normal subjects. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5488919 Wed, 07 Dec 2011 05:00:00 +0100 5488919 http://www.medworm.com/index.php?rid=5478594&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22029 AbstractWe investigated whether mesenchymal stem cells (MSCs) in synovial fluid (SF) increased in the knee with degenerated cartilage and osteoarthritis. SF was obtained from the knee joints of 22 patients with anterior cruciate ligament (ACL) injury during ACL reconstruction, and cartilage degeneration was evaluated arthroscopically. SF was also obtained from the knee joints of 6 healthy volunteers, 20 patients with mild osteoarthritis, and 26 patients with severe osteoarthritis, in which the grading was evaluated radiographically. The cell component in the SF was cultured for analyses. Synovium (SYN) and bone marrow (BM) were also harvested during total knee arthroplasties. The MSC number in SF was correlated with the cartilage degeneration score evaluated by arthroscopy. The MSC number ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5478594 Tue, 06 Dec 2011 05:00:00 +0100 5478594 http://www.medworm.com/index.php?rid=5478596&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22022 AbstractDisease‐related and senescent decrease of physiological variability in biological time‐series outputs (e.g., heart rate) has drawn increasing attention as a potential new type of biomarker. In this paradigm, measurement of variability in periodic motion may enable quantitative evaluation of functional limitation in people with musculoskeletal disorders. A novel technique to measure variability of leg motion patterns during level walking was used to study 52 adults with symptomatic knee osteoarthritis (OA), and 57 asymptomatic control subjects over a wide range of age (20–79 years). The hypothesis was that cycle‐to‐cycle variability in leg motion patterns, indexed by tri‐axial acceleration signal entropy, would be lower in those with greater age or with knee symptoms. Le... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5478596 Mon, 05 Dec 2011 05:00:00 +0100 5478596 http://www.medworm.com/index.php?rid=5478595&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22027 AbstractWe tested the hypothesis that erythropoietin (EPO) enhances bone formation after posterolateral spinal fusion (PLF) in a rabbit model. Thirty‐four adult rabbits underwent posterolateral intertransverse arthrodesis at the L5–L6 level using 2.0 g autograft per side. The animals were randomly divided into two groups receiving subcutaneous daily injections of either EPO or saline for 20 days. Treatment commenced 2 days preoperatively. Hemoglobin was monitored at baseline and 2, 4, and 6 weeks after fusion surgery. After euthanasia 6 weeks postoperatively, manual palpation, radiographic, and histomorphometric examinations were performed. Bone volume of the fusion mass was estimated by CT after 6 weeks. EPO increased bone fusion volume to 3.85 ccm (3.66–4.05) compared with 3.26... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5478595 Mon, 05 Dec 2011 05:00:00 +0100 5478595 http://www.medworm.com/index.php?rid=5460242&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22021 In this study, we observed a combinatorial relationship between intrinsic and extrinsic muscles to extend the distal phalanx via the terminal tendon of the finger extensor. Eleven fresh‐frozen human cadaver digit rays were used in these experiments (four index, four middle, three ring digits). All fingers had full joint motion without degenerative diseases. Fingers were individually mounted in a custom built jig fixed by a 1‐mm Kirschner wire that was driven into the rotational center of the distal interphalangeal (DIP) and proximal interphalangeal joints. Loads were applied to the extensor digit and dorsal interosseous tendons without flexor tendons, via sutures attached over low‐friction pulleys. Extension forces that crossed the DIP joint were measured by a force transducer couple... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5460242 Thu, 01 Dec 2011 17:28:51 +0100 5460242 http://www.medworm.com/index.php?rid=5433389&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22019 AbstractThe use of degradable composite materials in orthopedics remains a field of intense research due to their ability to support new bone formation and degrade in a controlled manner, broadening their use for orthopedic applications. Poly (lactide‐co‐glycolide) acid (PLGA), a degradable biopolymer, is now a popular material for different orthopedic applications and is proposed for use in tissue engineering scaffolds either alone or combined with bioactive ceramics. Interference screws composed of calcium phosphates and PLGA are readily available in the market. However, some reports highlight problems of screw migration or aseptic cyst formation following screw degradation. In order to understand these phenomena and to help to improve implant formulation, we have evaluated the effec... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5433389 Tue, 22 Nov 2011 16:54:59 +0100 5433389 http://www.medworm.com/index.php?rid=5433391&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22011 The objective of this study was to address a need for a better understanding of anatomical variations in ACL position and orientation within the joint. Specifically, variations in the ACL anatomy were assessed by testing for side‐to‐side ACL footprint location symmetry in a healthy population relative to the operative and contralateral knee in a patient population after traditional transtibial single‐bundle ACL reconstruction. MRI and three‐dimensional modeling techniques were used to determine the in vivo tibiofemoral ACL footprint centers and the resulting ACL orientations in both knees of 30 healthy subjects and 30 subjects after transtibial ACL reconstruction. While there were substantial inter‐subject variations in ACL anatomy, the side‐to‐side RMS differences in the ACL... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5433391 Mon, 21 Nov 2011 05:00:00 +0100 5433391 http://www.medworm.com/index.php?rid=5433390&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22017 AbstractIntervertebral disc (IVD) degeneration is accompanied by growth factor‐overexpression and increased cell proliferation, probably representing a tissue repair process. Accordingly, we studied the effect of exogenous and autocrine growth factors on the proliferation of human IVD cells. We observed that Platelet‐Derived Growth Factor (PDGF), basic Fibroblast Growth Factor (bFGF), and Insulin‐like Growth Factor‐I (IGF‐I) stimulate DNA synthesis of human IVD cells, through the activation of the MEK/ERK and the PI‐3K/Akt signal transduction pathways. Furthermore, medium conditioned (CM) by IVD cells induced DNA synthesis in the same cells, indicating the secretion of autocrine growth factors. The MEK/ERK and PI‐3K/Akt pathways were also induced by CM, while their inhibition... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5433390 Mon, 21 Nov 2011 05:00:00 +0100 5433390 http://www.medworm.com/index.php?rid=5424193&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22018 AbstractTo test whether a higher genetic risk load for knee osteoarthritis (OA) is associated with an earlier age at symptom onset. Six polymorphisms in GDF5, PTGS2, 7q22 locus, DVWA, DIO3, and ASPN that have been associated with knee OA were analyzed in 255 patients that had undergone total knee replacement (TKR) because of primary OA and in 457 healthy controls. We looked for association between the number of risk alleles in each patient and his age at symptom onset with linear regression and t‐tests between the upper and lower quartiles. There was not even a weak trend in the direction of a younger age at symptom onset in the patients carrying more risk alleles. Patients in the upper quartile of age at symptom onset (67.0 ± 2.8 years) carried the same number of OA risk alleles ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5424193 Sat, 19 Nov 2011 17:08:33 +0100 5424193 http://www.medworm.com/index.php?rid=5424196&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22016 AbstractPlatelet rich plasma (PRP) is the autologous plasma fraction with a platelet‐rich cellular component which is enriched with a number of growth factors. Due to its availability and low cost, PRP has become an increasingly popular clinical tool as an alternative source of growth factors for various applications, for example, tendon regeneration but with limited success in clinical trials. The main objective of the current study was to determine whether activated PRP [i.e., platelet rich plasma‐clot release (PRCR)] could be used to induce the proliferation and collagen synthesis in human tenocyte in vitro. The advantage of using PRCR is that the platelet‐derived bioactive factors are more concentrated and could initiate a more rapid and accelerated healing response than PRP. Our... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5424196 Fri, 18 Nov 2011 05:00:00 +0100 5424196 http://www.medworm.com/index.php?rid=5424195&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22020 AbstractGiant cell tumor of bone (GCT) presents with numerous osteoclast‐like multinucleated giant cells that are principally responsible for the extensive bone resorption by the tumor. Although the precise etiology of GCT remains uncertain, the accumulation of giant cells is partially due to the high expression of the receptor activator of nuclear factor‐κB ligand (RANKL) from the neoplastic stromal cells. Here, we have investigated whether parathyroid hormone‐related protein (PTHrP) plays a role in the pathogenesis of GCT. Immunohistochemistry results revealed PTHrP expression in the stromal cells of the tumor, and that its receptor, the parathyroid hormone type 1 receptor (PTH1R), is expressed by both the stromal cells and giant cells. PCR and Western blot analyses confirmed the ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5424195 Fri, 18 Nov 2011 05:00:00 +0100 5424195 http://www.medworm.com/index.php?rid=5424194&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22014 AbstractWe investigated the hypothesis that exogenous collagen cross‐linking can augment intact regions of tendon to mitigate mechanical propagation of partial tears. We first screened the low toxicity collagen cross‐linkers genipin, methylglyoxal and ultra‐violet (UV) light for their ability to augment tendon stiffness and failure load in rat tail tendon fascicles (RTTF). We then investigated cross‐linking effects in load bearing equine superficial digital flexor tendons (SDFT). Data indicated that all three cross‐linking agents augmented RTTF mechanical properties but reduced native viscoelasticity. In contrast to effects observed in fascicles, methylglyoxal treatment of SDFT detrimentally affected tendon mechanical integrity, and in the case of UV did not alter tendon mechanic... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5424194 Fri, 18 Nov 2011 05:00:00 +0100 5424194 http://www.medworm.com/index.php?rid=5411383&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21497 AbstractIndividuals with nerofibromatosis Type 1 (NF1) frequently suffer a spectrum of bone pathologies, such as abnormal skeletal development (scoliosis, congenital bowing, and congenital pseudoarthroses, etc), lower bone mineral density with increased fracture risk. These skeletal problems may result, in part, from abnormal osteoclastogenesis. Enhanced RAS/PI3K activity has been reported to contribute to abnormal osteoclastogenesis in Nf1 heterozygous (Nf1+/−) mice. However, the specific downstream pathways linked to NF1 abnormal osteoclastogenesis have not been defined. Our aim was to determine whether mammalian target of rapamycin (mTOR) was a key effector responsible for abnormal osteoclastogenesis in NF1. Primary osteoclast‐like cells (OCLs) were cultured from Nf1 wild‐type (Nf... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5411383 Thu, 17 Nov 2011 07:41:30 +0100 5411383 http://www.medworm.com/index.php?rid=5411377&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22015 AbstractLoosening of glenoid components in TSA is a main cause of failure. In reverse anatomy TSA designs used for unstable joints, fixation is particularly demanding. Strains developed around the glenoid rim of biomechanical sawbone scapulae implanted with (a) the original fixed‐fulcrum Bayley–Walker glenoid prosthesis in current clinical use, and (b) a revised version with conical cross‐section, were compared. The conical shape of the revised design was hypothesized to produce greater strains in the glenoid rim than the original tapered screw design. The 2D strain field at three accessible locations around the rim of each scapula was measured with three‐element rosette strain gauges for two types of simulated cancellous bone fill under applied physiologically relevant loads. The ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5411377 Thu, 17 Nov 2011 07:39:07 +0100 5411377 http://www.medworm.com/index.php?rid=5411378&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22013 AbstractEstrogen deficiency causes postmenopausal osteoporosis. The relationship between estrogen deficiency and the high failure rate after osteoporotic fracture treatment is unclear, as is the effect of possible interventions, either with anti‐resorptive agents or with anabolic agents such as bone morphogenetic proteins (BMPs). To investigate the influence of estrogen deficiency as well as the effect of early intervention, forty female wistar rats underwent ovarectomy (OVX) followed by low calcium diet. Ten rats underwent sham operations, followed by normal diet. After 6 weeks, a closed midshaft femoral fracture was induced. Ten animals received a systemic bisphosphonate injection, 10 injection of BMP‐7 in the fracture, and 10 a combination. All then received a normal diet. After 2 w... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5411378 Wed, 16 Nov 2011 05:00:00 +0100 5411378 http://www.medworm.com/index.php?rid=5411379&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22008 AbstractPatellofemoral (PF) pain is a common ailment of the lower extremity. A theorized cause for pain is patellar maltracking due to vasti muscle activation imbalance, represented as large vastus lateralis:vastus medialis (VL:VM) activation ratios. However, evidence relating vasti muscle activation imbalance to patellar maltracking is limited. The purpose of this study was to investigate the relationship between VL:VM activation ratio and patellar tracking measures, patellar tilt and bisect offset, in PF pain subjects and pain‐free controls. We evaluated VL:VM activation ratio and VM activation delay relative to VL activation in 39 PF pain subjects and 15 pain‐free controls during walking. We classified the PF pain subjects into normal tracking and maltracking groups based on patella... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5411379 Tue, 15 Nov 2011 05:00:00 +0100 5411379 http://www.medworm.com/index.php?rid=5411382&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22002 AbstractWear debris‐induced osteolysis is a major cause of orthopedic implant aseptic loosening, and various cell types, including macrophages, monocytes, osteoblasts, and osteoclasts, are involved. We recently showed that mesenchymal stem/osteoprogenitor cells (MSCs) are another target, and that endocytosis of titanium (Ti) particles causes reduced MSC proliferation and osteogenic differentiation. Here we investigated the mechanistic aspects of the endocytosis‐mediated responses of MSCs to Ti particulates. Dose‐dependent effects were observed on cell viability, with doses >300 Ti particles/cell resulting in drastic cell death. To maintain cell viability and analyze particle‐induced effects, doses <300 particles/cell were used. Increased production of interleukin‐8 (IL‐8)... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5411382 Mon, 14 Nov 2011 05:00:00 +0100 5411382 http://www.medworm.com/index.php?rid=5411381&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22000 In conclusion, Wnt/β‐catenin signaling activity in the NC within the NC‐rich NP and in culture supports the role of this cell as a potential progenitor cell; increased Wnt/β‐catenin signaling activity in early IVD degeneration may be a reflection of its dual role. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5411381 Mon, 14 Nov 2011 05:00:00 +0100 5411381 http://www.medworm.com/index.php?rid=5411380&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22009 We examined the mechanical response of the distal radius pre‐fracture and at fracture under dynamic impact loads. The distal third of eight human cadaveric radii were potted and placed in a custom designed pneumatic impact system. The distal intra‐articular surface of the radius rested against a model scaphoid and lunate, simulating 45° of wrist extension. The scaphoid and lunate were attached to a load cell that in turn was attached to an impact plate. Impulsive impacts were applied at increasing energy levels, in 10 J increments, until fracture occurred. Three 45° stacked strain gauge rosettes were affixed along the length of the radius quantifying the bone strains. The mean (SD) fracture energy was 45.5 (16) J. The mean (SD) resultant impact reaction force (IRFr) at failure wa... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5411380 Mon, 14 Nov 2011 05:00:00 +0100 5411380 http://www.medworm.com/index.php?rid=5390748&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22012 AbstractThe purpose of this study was to develop and validate an in vivo mouse model of tendon fatigue and use this model to investigate and quantify the physical manifestations of fatigue damage in mouse tendon. Patellar tendons of C57BL/6J mice were fatigue loaded at 2 Hz to three endpoints (4 N peak force per cycle for 1 h, 6 N for 1 h, and 4 N for 2 h), during which hysteresis, tangent stiffness, and peak strain of each cycle were measured. Damage accumulation was then quantified using in situ histology, and each tendon was loaded monotonically to failure. Histological damage increased significantly in all three groups (≥2‐fold), and monotonic stiffness decreased significantly in the 6 N, 1 h and 4 N, 2‐h groups (∼25%), suggesting that damage initially manif... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5390748 Thu, 10 Nov 2011 17:52:26 +0100 5390748 http://www.medworm.com/index.php?rid=5390750&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22007 AbstractProprioception is important in maintaining shoulder joint stability. Previous studies investigated the effects of unconstrained multiplanar motion, with subjects able to move freely in space, on repositioning tasks for active shoulder motion but not passive motion. We sought to further explore joint position sense with 3D passive, robot‐guided motions. We hypothesized that target repositioning error would be greater in the case of passively placed targets than for actively placed targets. To investigate, 15 healthy individuals participated (8 female, 7 male), who were at most 6 ft (183 cm) tall to accommodate the equipment, and who had no history of shoulder injury, surgery, or significant participation in throwing sports. Target orientations were centered at 44° of elevatio... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5390750 Wed, 09 Nov 2011 05:00:00 +0100 5390750 http://www.medworm.com/index.php?rid=5390749&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22010 We examined the influence of partial meniscectomy of 10 mm width on 10 human cadaveric knee joints, as it is performed during the treatment of radial tears in the posterior horn of the medial meniscus, on maximum contact pressure, contact area (CA), and meniscal hoop strain in the lateral and medial knee compartments. In case of 0° and 30° flexion angle, 20% and 50% partial meniscectomy did not influence maximum contact pressure and area. Only in case of 60° knee flexion, 50% partial resection increased medial maximum contact pressure and decreased the medial CA statistically significant. However, 100% partial resection increased maximum contact pressure and decreased CA significantly in the meniscectomized medial knee compartment in all tested knee positions. No significant differenc... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5390749 Wed, 09 Nov 2011 05:00:00 +0100 5390749 http://www.medworm.com/index.php?rid=5390751&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22006 AbstractSuccessful rotator cuff tendon repair depends on secure tendon‐to‐bone healing. Recombinant human parathyroid hormone (rhPTH) has been shown in multiple studies to accelerate bone healing. Recent studies have also shown that rhPTH is chondrogenic by increasing chondrocyte recruitment and differentiation. We hypothesized that rhPTH would improve tendon‐to‐bone healing in a rat rotator cuff repair model. One hundred and fourteen Sprague Dawley rats underwent division and repair of the supraspinatus tendon. Fifty seven rats received daily subcutaneous injections of 10 µg/kg of rhPTH. Rats were sacrificed at 3, 7, 14, 28, and 56 days for histologic and immunohistochemical analysis. In addition, rats in each group were sacrificed at 14, 28, and 56 days for biomechanical testi... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5390751 Tue, 08 Nov 2011 05:00:00 +0100 5390751 http://www.medworm.com/index.php?rid=5390755&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22003 AbstractHistological and molecular changes were examined to investigate the effects of long‐term administration of glucosamine (GlcN) and chondroitin sulfate (CS) in a model of spontaneous osteoarthritis (OA) in Hartley guinea pigs. Three groups of female 3‐week‐old Hartley guinea pigs received GlcN, CS, and neither agent, respectively. Five animals in each group were sacrificed at 8, 12, and 18 months of age. At 8 months of age, Hartley guinea pigs had severe degeneration of knee joint cartilage, chondrocyte apoptosis, marked reduction of tissue total RNA, decreases of aggrecan and collagen type 2 mRNAs, and increases in MMP‐3 and MMP‐8 mRNAs. Long‐term administration of GlcN and CS reduced cartilage degeneration at 8 months of age. The marked loss of total RNA and the increas... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5390755 Fri, 04 Nov 2011 04:00:00 +0100 5390755 http://www.medworm.com/index.php?rid=5390754&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21588 AbstractStudies have demonstrated increased myofibroblasts in contractures. However, the timeline is largely unknown. The aim of this study was to determine the number of myofibroblasts in contracting joint capsules at 3‐time points over a 24‐week period. Eighteen rabbits subjected to a surgical procedure designed to elicit a knee joint contracture were divided into three groups of six. Rabbits were sacrificed at each respective time point and myofibroblasts in the joint capsules were quantified using immunohistochemistry. The percent of myofibroblasts was significantly elevated in the operated limbs compared to the control limbs at 2 weeks (20% vs. 7%, respectively; p = 0.014). There was no difference in the percent of myofibroblasts between the operated and control limbs at 8 or ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5390754 Fri, 04 Nov 2011 04:00:00 +0100 5390754 http://www.medworm.com/index.php?rid=5390753&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22004 This study investigated the effect of low‐magnitude high‐frequency (LMHF) loading via whole body vibration on bone‐implant osseointegration in osteoporotic rats, and a comparison was made between LMHF vibration and alendronate on their effects. Thirty rats were ovariectomized to induce osteoporosis, and then treated with LMHF vibration (VIB) or alendronate (ALN) or a control treatment (OVX). Another 10 rats underwent sham operation to establish Sham control group. Prior to treatment, hydroxyapatite (HA)‐coated titanium implants were inserted into proximal tibiae bilaterally. Both LMHF vibration and alendronate treatment lasted for 8 weeks. Histomorphometrical assess showed that both group VIB, ALN and Sham significantly increased bone‐to‐implant contact and peri‐implant bone ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5390753 Fri, 04 Nov 2011 04:00:00 +0100 5390753 http://www.medworm.com/index.php?rid=5390752&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22005 AbstractIn cartilage repair, platelet‐rich plasma (PRP) is used in one‐step approaches utilizing microfracture and matrix‐induced chondrogenesis procedures, bone marrow‐derived cell transplantation, or intra‐articular injection. The aim of our study was to evaluate the effect of human PRP on the migration and chondrogenic differentiation of human subchondral progenitors. Human progenitors were derived from subchondral cortico‐spongious bone (CSP), were analyzed for their migration capacity upon PRP treatment in 96‐well chemotaxis assays and cultured in high‐density pellet cultures under serum‐free conditions in the presence of 5% PRP. Chemotaxis assays showed that 0.1–100% PRP significantly (p < 0.05) stimulate the migration of CSP compared to untreated controls.... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5390752 Fri, 04 Nov 2011 04:00:00 +0100 5390752 http://www.medworm.com/index.php?rid=5366744&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.22001 In this study, we compared the viscoelastic behavior of human cortical bone between genders by using nanoindentation at a fixed load of 10 mN to measure the creep time constant. Bones from females had a significantly greater time constant, indicating slower creep and relaxation, than bones from males. The creep time constants decreased with increasing tissue modulus. The mineralization, collagen content, and collagen cross‐link density, which were bulk measurements, were analyzed to determine if the differences in viscoelastic behavior were explained by compositional differences in the bone. However, none of the parameters differed between genders, nor were they correlated to the viscoelastic time constant. As such, the difference must depend on other matrix proteins that we did not as... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5366744 Fri, 04 Nov 2011 02:09:37 +0100 5366744 http://www.medworm.com/index.php?rid=5366745&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21586 AbstractPrevious genome‐wide microarray analysis of candidate genes involved in the ossification of the posterior longitudinal ligament (OPLL) of the spine resulted in the identification of a novel, clinically relevant gene encoding bone morphogenetic protein 4 (BMP4) but was defined only by its expression patterns. The complete genomic BMP4 coding DNA from 450 patients with OPLL and 550 matched controls were sequenced and compared. We identified 18 SNPs, among which the minor alleles of SNP8 (C>T; p < 0.001; OR: 1.58), SNP13 (rs17563C>T; p < 0.001; OR: 1.76), and SNP14 (rs76335800A>T; p < 0.001; OR: 1.68) were associated with OPLL. Logistic regression analysis showed that the additive model of SNP8 (p < 0.001; OR: 3.48), SNP13 (p < 0.001; OR: ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5366745 Wed, 02 Nov 2011 04:00:00 +0100 5366745 http://www.medworm.com/index.php?rid=5366749&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21585 AbstractOsteosarcoma (OS) is a malignant bone tumor predominantly affecting children and adolescents. OS has a 60% survival rate with current treatments; hence, there is a need to identify novel adjuncts to chemotherapeutic regimens. In this pilot study, we investigated the dose‐response to 1α,25‐dihdroxyvitamin D3 (1,α 25(OH)2D3) and 25‐hydroxyvitamin D3 (25(OH)D3) by human OS cell lines, SaOS‐2, and 143B. We hypothesized that 1,α 25(OH)2D3 and 25(OH)D3 would stimulate differentiation and induce apoptosis in OS cells in a dose‐dependent manner. Human OS cell lines, SaOS‐2, and 143B, were treated with 1,α 25(OH)2D3 or 25(OH)D3 or an ethanol control, respectively, at concentrations ranging from 1 to 1,000 nM. Ki67 (a marker of cellular proliferation) immunocytochemistry re... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5366749 Mon, 31 Oct 2011 04:00:00 +0100 5366749 http://www.medworm.com/index.php?rid=5366748&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21571 In this study we describe the effects of fluid flow, particularly hydrostatic pressure and wall shear stress, on the Ca2+ signaling response of bovine articular chondrocytes in 3D culture. Using well‐established alginate hydrogel system to maintain spherical chondrocyte morphology, we altered solid volume fraction to change scaffold mechanics. Fluid velocities in the bulk of the scaffolds were directly measured via an optical technique and scaffold permeability and aggregate modulus was characterized to quantify the mechanical stimuli presented to cells. Ca2+ signaling response to direct perfusion of chondrocyte‐seeded scaffolds increased monotonically with flow rate and was found more directly dependent on fluid velocity rather than shear stress or hydrostatic pressure. Chondrocytes i... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5366748 Mon, 31 Oct 2011 04:00:00 +0100 5366748 http://www.medworm.com/index.php?rid=5366747&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21587 AbstractThe potential for peri‐implant bone yielding and subsequent loosening of Ilizarov ring‐wire external fixation systems was investigated using non‐linear finite element (FE) analyses. A strain‐based plasticity model was employed to simulate bone yielding. FE models also incorporated contact behavior at the wire‐bone interface, orthotropic elasticity, and periosteal‐endosteal variation of bone properties. These simulations were used to determine the extent and location of yielding with change in age‐related bone structure and properties for the bone‐Ilizarov construct at the tibial midshaft. At critical wire‐bone interfaces, the predicted volume of yielded bone with four wires (on either side of the fracture) was ∼40% of that with two wires. Old‐aged cases showed... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5366747 Mon, 31 Oct 2011 04:00:00 +0100 5366747 http://www.medworm.com/index.php?rid=5366746&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21583 AbstractThe transverse carpal ligament (TCL) influences carpal stability and carpal tunnel mechanics, yet little is known about its mechanical properties. We investigated the tissue properties of TCLs extracted from eight cadaver arms and divided into six tissue samples from the distal radial, distal middle, distal ulnar, proximal radial, proximal middle, and proximal ulnar regions. The 5% and 15% strains were applied biaxially to each sample at rates of 0.1, 0.25, 0.5, and 1%/s. Ligament thickness ranged from 1.22 to 2.90 mm. Samples from the middle of the TCL were thicker proximally than distally (p < 0.013). Tissue location significantly affected elastic modulus (p < 0.001). Modulus was greatest in the proximal radial samples (mean 2.8 MPa), which were 64% and 44% grea... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5366746 Mon, 31 Oct 2011 04:00:00 +0100 5366746 http://www.medworm.com/index.php?rid=5350283&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21580 This study showed that 90 days after HA IA injections, U‐CTX II levels significantly decrease compared to baseline, suggesting a slowdown of type II collagen degradation. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5350283 Thu, 27 Oct 2011 04:58:36 +0100 5350283 http://www.medworm.com/index.php?rid=5366752&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21574 AbstractThe extent to which bone tissue composition varies across anatomic sites in normal or pathologic tissue is largely unknown, although pathologic changes in bone tissue composition are typically assumed to occur throughout the skeleton. Our objective was to compare the composition of normal cortical and trabecular bone tissue across multiple anatomic sites. The composition of cadaveric bone tissue from three anatomic sites was analyzed using Fourier transform infrared imaging: iliac crest (IC), greater trochanter (GT), and subtrochanteric femur (ST). The mean mineral:matrix ratio was 20% greater in the subtrochanteric cortex than in the cortices of the iliac crest (p = 0.004) and the greater trochanter (p = 0.02). There were also trends toward 30% narrower crystallinity distr... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5366752 Thu, 27 Oct 2011 04:00:00 +0100 5366752 http://www.medworm.com/index.php?rid=5366751&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21578 AbstractTo investigate the atrophy of supraspinatus (SSP) muscle tissue and accumulation of extramuscular fat (e‐fat) and intramuscular fat (i‐fat) after delayed repair of the SSP tendon, and to correlate CT findings with histology. One SSP tendon of 36 rabbits was transected, then repaired in groups of 12 at 4, 8, or 12 weeks and then followed for 12 weeks. Thirty‐six normal shoulders served as controls. We compared the SSP muscle, e‐fat weights and volumes, muscle tissue and i‐fat areas on histology, e‐fat and attenuation values on CT between the experimental and control shoulders. CT‐to‐histology correlations were run. SSP muscle tissue atrophy, e‐fat and i‐fat accumulation were present after tendon repair delayed by 4, 8, or 12 weeks (all p < 0.05). Both e‐... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5366751 Thu, 27 Oct 2011 04:00:00 +0100 5366751 http://www.medworm.com/index.php?rid=5366750&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21584 AbstractMen are reportedly at higher risk of plantar flexor muscle injury and Achilles tendon ruptures than women. Biomechanical parameters are thought to play a role in the higher frequency of injury to males. One parameter is the stiffness of tissues; a stiff tissue cannot absorb sufficient energy with loading, and subsequently may be more likely to be injured. Thus, our purpose was to investigate the gender difference in the geometrical parameters of plantar flexor's muscle–tendon complex and the stiffness of both active and passive parts of the series elastic component (SSEC1 and SSEC2, respectively). Using the alpha method on data obtained from quick stretches to the plantar flexors performed during isometric contractions, SSEC1 and SSEC2 were assessed. Plantar flexor muscles and Ac... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5366750 Thu, 27 Oct 2011 04:00:00 +0100 5366750 http://www.medworm.com/index.php?rid=5350290&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21577 This study aims to quantitatively characterize bone quality and tumor burden within a new rat model of mixed osteolytic/osteoblastic spinal metastases. Mixed vertebral metastases were analyzed in nude rats 21‐days post intracardiac injection of Ace‐1 canine prostate cancer cells. Vertebral micro‐architecture was assessed in µCT images. Histologic processing quantified tumor burden (PTHrP), osteoclast activity (TRAP), and osteoid formation (Goldner's Trichrome) in ½ of all samples. Remaining samples were mechanically tested to failure in compression. Metastatically involved vertebrae exhibited extreme osteolysis, evident through an increase in osteoclasts leading to significantly reduced trabecular bone volume. Metastatically involved vertebrae also exhibited increased osteoid chara... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5350290 Mon, 24 Oct 2011 04:00:00 +0100 5350290 http://www.medworm.com/index.php?rid=5350289&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21579 AbstractDespite improvements in the treatment of osteosarcoma, there is a need for new therapeutic strategies, in particular for the treatment of recurrent tumors and metastases. Adoptive immunotherapy with Vγ9Vδ2 T lymphocytes represents an attractive strategy. We have investigated combining adoptive immunotherapy with Vγ9Vδ2 T cells and zoledronate to optimize osteosarcoma therapy. Vγ9Vδ2 T cells, from healthy volunteers and patients with osteosarcoma, cultures alone demonstrated moderate or poor cytotoxic activity against osteosarcoma cell lines, respectively. The addition of zoledronate further increased cytotoxicity in vitro. This enhancement was largely dependent on the granule exocytose and partly on TRAIL pathways, was TCR‐mediated and partly NKG2D‐mediated. These data su... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5350289 Mon, 24 Oct 2011 04:00:00 +0100 5350289 http://www.medworm.com/index.php?rid=5350288&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21581 In conclusion, cobalt and chromium ions reduce human osteoblast activity, reduce OPG/RANKL ratio and lead to oxidative stress. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5350288 Mon, 24 Oct 2011 04:00:00 +0100 5350288 http://www.medworm.com/index.php?rid=5350287&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21582 AbstractThe aim of this study was to evaluate histological changes in torn (0.5–27 weeks after injury) and osteoarthritic (OA) knee menisci versus normal menisci after PAS‐AB, SAF‐O‐FG, and immunostaining for CD34, CD31, and smooth muscle actin (SMA). Cell layers in the superficial zone and the cell density in the deep zone of the menisci were counted. In the superficial zone of normal menisci, cells expressing CD34 were demonstrated. CD34+ CD31− cells were absent in OA menisci and disappeared in torn menisci as a function of time. In contrast, an increase of SMA+ cells combined with an increase of cell layers was observed in the superficial zone of torn menisci. SMA+ cells were absent in normal and OA menisci. The predominant tissue type in torn menisci evolved from fibrocartila... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5350287 Mon, 24 Oct 2011 04:00:00 +0100 5350287 http://www.medworm.com/index.php?rid=5350286&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21575 AbstractWe elucidated the gender and condylar effects on distal femur morphology (DFM) while evaluating a newly developed computational framework that enables fully automated analyses of DFM in an objectively defined sagittal plane. Ninety high‐resolution CT‐acquired distal femur models from 51 males and 39 females were analyzed. The models were accurately characterized (mean least‐squares fitting residual <0.16 mm), and re‐oriented to a unified sagittal plane; three morphometric measures were extracted from each model: the semi‐major (a) and semi‐minor (b) axis lengths of the best‐fitted ellipse, and the radius (r) of the smallest flexion facet—a circle with the smallest radius best‐fitted to the posterior articulating surface. Statistical analyses employing nonpara... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5350286 Mon, 24 Oct 2011 04:00:00 +0100 5350286 http://www.medworm.com/index.php?rid=5350285&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21573 AbstractVertebral endplate damage is associated with intervertebral disc (IVD) degeneration (DD) in vivo as confirmed by in‐vitro investigations. Our aims were to further characterize the process of DD using an in vitro full‐organ culture model and to elucidate whether significant endplate damage or impact loading alone is pivotal for the initiation of DD. Rabbit spinal segments (n = 80) were harvested, subjected to pure axial impact loading (n = 40) using a custom‐made device, and cultured for 28 days. The applied threshold energy (0.76 J) induced endplate fractures in 21 specimens (group A); 19 remained intact (group B). Markers for DD (cell viability, apoptosis, necrosis, matrix remodeling, and inflammation) were monitored for 28 days post‐trauma in the annulus fibrosu... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5350285 Mon, 24 Oct 2011 04:00:00 +0100 5350285 http://www.medworm.com/index.php?rid=5350284&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21572 AbstractAnterior cruciate ligament (ACL) injuries most frequently occur under the large loads associated with a unipedal jump landing involving a cutting or pivoting maneuver. We tested the hypotheses that internal tibial torque would increase the anteromedial (AM) bundle ACL relative strain and strain rate more than would the corresponding external tibial torque under the large impulsive loads associated with such landing maneuvers. Twelve cadaveric female knees [mean (SD) age: 65.0 (10.5) years] were tested. Pretensioned quadriceps, hamstring, and gastrocnemius muscle‐tendon unit forces maintained an initial knee flexion angle of 15°. A compound impulsive test load (compression, flexion moment, and internal or external tibial torque) was applied to the distal tibia while recording the... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5350284 Mon, 24 Oct 2011 04:00:00 +0100 5350284 http://www.medworm.com/index.php?rid=5338755&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21570 We describe a multi‐segmented foot model comprising lower leg, rearfoot, midfoot, lateral forefoot, medial forefoot, and hallux for routine use in a clinical setting. The Ghent Foot Model describes the kinematic patterns of functional units of the foot, especially the midfoot, to investigate patient populations where midfoot deformation or dysfunction is an important feature, for example, rheumatoid arthritis patients. Data were obtained from surface markers by a 6 camera motion capture system at 500 Hz. Ten healthy subjects walked barefoot along a 12 m walkway at self‐selected speed. Joint angles (rearfoot to shank, midfoot to rearfoot, lateral and medial forefoot to midfoot, and hallux to medial forefoot) in the sagittal, frontal, and transverse plane are reported according to an... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5338755 Sun, 23 Oct 2011 05:42:05 +0100 5338755 http://www.medworm.com/index.php?rid=5338756&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21576 In conclusion, aging potentiated the ciprofloxacin‐mediated inhibition of migration, proliferation, and expression of type III collagen of tenocytes. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5338756 Fri, 21 Oct 2011 04:00:00 +0100 5338756 http://www.medworm.com/index.php?rid=5338757&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21569 AbstractFrictional resistance to tendon gliding is minimized by surrounding loose areolar tissue. During periods of prolonged immobilization, for example, post‐tendon‐repair, adhesions can form between these two adjacent tissues, thereby limiting tendon function. Anti‐adhesive agents can be applied during surgery to prevent adhesion formation, whilst reportedly providing some reduction in friction during in vitro tendon‐bony pulley investigations. This bio‐tribological study evaluates whether application of these agents can improve the lubrication between the tendon and surrounding tissue, thus potentially reducing the risk of re‐rupturing the tendon at the repair site. The use of bovine synovial fluid (BSF) enabled an approximation of the in vivo lubrication regime, and subseq... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5338757 Wed, 19 Oct 2011 04:00:00 +0100 5338757 http://www.medworm.com/index.php?rid=5325824&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21565 AbstractThe most common histological finding in carpal tunnel syndrome (CTS) is non‐inflammatory fibrosis and thickening of the subsynovial connective tissue (SSCT) in the tunnel. While the cause of SSCT fibrosis and the relationship of SSCT fibrosis and CTS are unknown, one hypothesis is that SSCT injury causes fibrosis, and that the fibrosis then leads to CTS. We investigated the sensitivity of the SSCT to injuries. Two types of surgical interventions were performed in a rabbit model: A skin incision with tendon laceration and SSCT stretching sufficient to damage the SSCT, and skin incision alone. Twelve weeks after surgery, the rabbit carpal tunnel tissues were studied with immunochemistry for TGF‐β receptors 1, 2, and 3, collagen III, and collagen VI. All TGF‐β receptors were e... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5325824 Wed, 19 Oct 2011 02:49:00 +0100 5325824 http://www.medworm.com/index.php?rid=5325825&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21567 This study showed the feasibility of computer‐assisted patellar resection, which could lead to reduced pain and complications after TKA. The feedback provided could also make patellar CAS a valuable training tool. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5325825 Mon, 17 Oct 2011 04:00:00 +0100 5325825 http://www.medworm.com/index.php?rid=5317304&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21566 This study examined the implant–endplate interface using a cyclic fatigue loading protocol in an attempt to model the subsidence seen in vivo. The superior endplate from 30 cervical vertebrae (C3 to T1) were harvested and biomechanically tested in axial compression with one of three implants: Fibular allograft; titanium mesh cage packed with cancellous chips; and trabecular metal. Each construct was cyclically loaded from 50 to 250 N for 10,000 cycles. Nondestructive cyclic loading of the cervical endplate–implant construct resulted in a stiffer construct independent of the type of the interbody implant tested. The trabecular metal construct demonstrated significantly more axial stability and significantly less subsidence in comparison to the titanium mesh construct. Although the all... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5317304 Sat, 15 Oct 2011 18:51:09 +0100 5317304 http://www.medworm.com/index.php?rid=5317305&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21568 AbstractDue to the annular gap between intramedullary (IM) nails and the endosteal surface, high interfragmentary movement can occur under loading. This could prolong the healing time, particularly for thin IM nails that are often used for unreamed IM nailing. The aims of our study were to determine the influence of the nail diameter on the healing time of human tibial shaft fractures and to investigate whether the healing time could be shortened by increasing the stiffness of the implant material. Therefore, a corroborated numerical model for simulating the fracture healing process in humans was used to simulate the healing process of human tibial fractures treated with IM nails. The calculated healing time (up to 71 weeks) was longest for transverse fractures treated with thin IM nails m... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5317305 Fri, 14 Oct 2011 04:00:00 +0100 5317305 http://www.medworm.com/index.php?rid=5298461&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21564 AbstractGeneral agreement is that flexion and extension gaps should be equal and symmetrical in total knee arthroplasty (TKA) procedures. However, comparisons using a standard TKA approach to normal knee joints that have not undergone bone resection are currently unavailable. Since bony preparation can influence capsule and ligament tension, our purpose was to perform measurements without this influence. Ten normal cadaveric knees were assessed using a standard medial parapatellar TKA approach with patellar subluxation. Gap measurements were carried out twice each alternating 100 and 200 N per compartment using a prototypical force‐determining ligament balancer without the need for bony resection. Initial measurements were performed in extension, followed by 90° of flexion. The ACL wa... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5298461 Sun, 09 Oct 2011 16:24:24 +0100 5298461 http://www.medworm.com/index.php?rid=5263204&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21562 AbstractWe investigated the median nerve deformation in the carpal tunnel in patients with carpal tunnel syndrome and controls during thumb, index finger, middle finger, and a four finger motion, using ultrasound. Both wrists of 29 asymptomatic volunteers and 29 patients with idiopathic carpal tunnel syndrome were evaluated by ultrasound. Cross‐sectional images during motion from full extension to flexion were recorded. Median nerve cross‐sectional area, perimeter, aspect ratio of the minimal enclosing rectangle, and circularity in extension and flexion positions were calculated. Additionally, a deformation index was calculated. We also calculated the intra‐rater reliability. In both controls and patients, the median nerve cross‐sectional area became significantly smaller from exte... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5263204 Thu, 29 Sep 2011 17:26:44 +0100 5263204 http://www.medworm.com/index.php?rid=5252452&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21563 This study investigated the load‐modifying and clinical efficacy of variable‐stiffness shoes after 12 months in subjects with medial compartment knee osteoarthritis. Subjects who completed a prior 6‐month study were asked to wear their assigned constant‐stiffness control or variable‐stiffness intervention shoes during the remainder of the study. Changes in peak knee adduction moment, total Western Ontario and McMaster Universities (WOMAC), and WOMAC pain scores were assessed. Seventy‐nine subjects were enrolled, and 55 completed the trial. Using an intention‐to‐treat analysis, the variable‐stiffness shoes reduced the within‐day peak knee adduction moment (−5.5%, p < 0.001) in the intervention subjects, while the constant‐stiffness shoes increased the peak kne... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5252452 Mon, 26 Sep 2011 04:40:46 +0100 5252452 http://www.medworm.com/index.php?rid=5228602&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21560 This study was undertaken to investigate the age‐related differences of monocyte chemotactic protein‐1 (MCP‐1) and matrix metalloproteinase‐3 (MMP‐3) expression in mouse intervertebral disc (IVD) and to determine whether MMP‐3 plays a role in disc degeneration. Expression of MCP‐1 and MMP‐3 mRNA in mouse IVD was assessed by quantitative PCR. The ability of MCP‐1 and MMP‐3 expression in IVD to respond to TNF‐α or TWEAK stimulation was examined by quantitative PCR, WB, ELISA, and immunohistochemistry. IVD derived from MMP‐3‐deficient and wild‐type mice were compared using Safranin‐O staining and immunohistochemistry. mRNA levels of MCP‐1 and MMP‐3 in IVD significantly diminished and the ability of MCP‐1 or MMP‐3 expression to respond to TNF‐α or TWEA... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5228602 Mon, 19 Sep 2011 07:45:56 +0100 5228602 http://www.medworm.com/index.php?rid=5228606&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21537 AbstractExtensive periosteal stripping (PS) is a risk factor for post‐radiation pathologic fracture following surgery for extremity soft tissue tumors. The purpose of this study was to determine the effects of PS on bone structure and mechanical properties. Thirty‐one skeletally mature mice underwent PS, with circumferential removal of periosteum from an 8‐mm segment of the mid‐diaphysis of the left femur. Thirty‐one control mice underwent sham surgery in which the femur was isolated without manipulation of the periosteum. At 2, 6, 12, or 26 weeks following surgery, the left femora were examined by micro‐CT to quantify cortical thickness (CtTh), cross‐sectional area (CSA), bone volume (BV), and polar moment of inertia (PMI). Three‐point mechanical bend testing was performed... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5228606 Fri, 16 Sep 2011 04:00:00 +0100 5228606 http://www.medworm.com/index.php?rid=5228605&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21558 AbstractThe present study examined the effect of ADAMTS5 (TS5) knockout on the properties of murine flexor digitorum longus (FDL) and Achilles tendons. FDL and Achilles tendons were analyzed using biomechanical testing, histology, and immunohistochemistry; further characterization of FDL tendons was conducted using transmission electron microscopy (collagen fibril ultrastructure), SDS–PAGE (collagen content and type), fluorescence‐assisted carbohydrate electrophoresis for chondroitin sulfate and hyaluronan, and Western blotting for aggrecan, versican, and decorin abundance and distribution. FDL tendons of TS5−/− mice showed a 33% larger cross‐sectional area, increased collagen fibril area fraction, and decreased material properties relative to those of wild type mice. In TS5−/�... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5228605 Fri, 16 Sep 2011 04:00:00 +0100 5228605 http://www.medworm.com/index.php?rid=5228604&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21552 AbstractThe mechanisms by which articular surface impact causes post‐traumatic osteoarthritis are not well understood, but studies of cartilage explants implicate the mitochondrial electron transport chain as a source of oxidants that cause chondrocyte death from mechanical injury. The linkage of mitochondria to the cytoskeleton suggests that they might release oxidants in response to mechanical strain, an effect that disrupting the cytoskeleton would prevent. To test this we investigated the effects of agents that promote the dissolution of microfilaments (cytochalasin B) or microtubules (nocodazole) on oxidant production and chondrocyte death following impact injury. Osteochondral explants treated with cytochalasin B or nocodazole for 4 h were impacted (7 J/cm2) and stained for oxi... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5228604 Fri, 16 Sep 2011 04:00:00 +0100 5228604 http://www.medworm.com/index.php?rid=5228603&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21559 In conclusion, TDSCs promoted earlier and better repair in a rat patellar tendon window defect model. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5228603 Fri, 16 Sep 2011 04:00:00 +0100 5228603 http://www.medworm.com/index.php?rid=5228609&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21554 AbstractPeriprosthetic osteolysis is one of the leading causes of total joint revision procedures. If allowed to progress in the absence of radiographic diagnosis and/or proper medical treatment, osteolysis may result in aseptic loosening yielding failure of the implant and the need for complex revision arthroplasty. The purpose of this review was to assess the current understanding of periprosthetic osteolysis with an emphasis on host factors and future directions. A PubMed search was conducted using the following key words; osteolysis, periprosthetic osteolysis, osteolysis imaging. Pertinent articles, as it pertained to the outline of the review, were selected. Periprosthetic osteolysis stems from numerous risk factors. Osteolysis host characteristic risk factors include gender, body wei... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5228609 Thu, 15 Sep 2011 04:00:00 +0100 5228609 http://www.medworm.com/index.php?rid=5228608&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21556 In conclusion, this study demonstrates that MSCs from PB maintain similar characteristics and have similar chondrogenic differentiation potential to those derived from BM, while producing comparable s‐GAG expressions to chondrocytes. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5228608 Thu, 15 Sep 2011 04:00:00 +0100 5228608 http://www.medworm.com/index.php?rid=5228607&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21561 In conclusion, immunomodulation by a C5aR‐antagonist could abolish the deleterious effects of a thoracic trauma on fracture healing, possibly by influencing the function of inflammatory and bone cells locally at the fracture site. C5a could possibly represent a target to prevent delayed bone healing in patients with severe trauma. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5228607 Thu, 15 Sep 2011 04:00:00 +0100 5228607 http://www.medworm.com/index.php?rid=5228611&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21553 AbstractDamaged bone is sensitive to mechanical stimulation throughout the remodeling phase of bone healing. Muscle damage and muscular atrophy associated with open fractures and subsequent fixation are not beneficial to maintaining optimum conditions for mechanical stability. The aim of this study was to investigate whether local muscle atrophy and dysfunction affect fracture healing in a rat femur fracture model. We combined the rat model of a short period atrophy of the quadriceps with femur fracture. Forty‐four‐month‐old male Wistar rats were adopted for this study. Two units of botulinum toxin‐A (BXTA) were administered locally into the right side of the quadriceps of each rat, while the same dose of saline was injected into the contralateral quadriceps. After BXTA had been fu... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5228611 Wed, 14 Sep 2011 04:00:00 +0100 5228611 http://www.medworm.com/index.php?rid=5228610&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21549 AbstractPeople are not equally disabled by combined anterior cruciate ligament (ACL)/medial collateral ligament (MCL) injuries, nor do they all develop osteoarthritis (OA). Although biological/biomechanical causes are not clear, some association presumably exists between joint instability and OA development. We hypothesized that degree of OA development following standardized complete ACL/MCL injuries will vary directly with the degree of biomechanical abnormality between individuals. Three groups of sheep were used to test the hypothesis: 17 normal, 9 ACL/MCL transected, and 7 sham animals. Normal joints were assessed morphologically while sham and experimental animals had gait assessment pre‐ and at 4 and 20 weeks post‐surgery, with cartilage and bone changes being mapped and graded ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5228610 Wed, 14 Sep 2011 04:00:00 +0100 5228610 http://www.medworm.com/index.php?rid=5212422&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21548 AbstractThe biological mechanisms leading to periprosthetic osteolysis involve both chemokines and the monocyte/macrophage cell lineage. Whether MCP‐1 plays a major role in macrophage recruitment in the presence of wear particles is unknown. We tested two hypotheses: (1) that exogenous local delivery of MCP‐1 induces systematic macrophage recruitment and (2) that blockade of the MCP‐1 ligand‐receptor axis decreases macrophage recruitment and osteolysis in the presence of ultra high molecular weight polyethylene (UHMWPE) particles. Six groups of nude mice were used. We used non‐invasive imaging to assay macrophage recruitment and osteolysis. A murine macrophage cell line and primary wild type and CCR2 knockout murine macrophages were used as the reporter cells. Particles were infu... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5212422 Tue, 13 Sep 2011 06:53:46 +0100 5212422 http://www.medworm.com/index.php?rid=5212426&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21550 AbstractScleraxis is a basic helix–loop–helix transcription factor that plays a central role in promoting fibroblast proliferation and matrix synthesis during the embryonic development of tendons. Mice with a targeted inactivation of scleraxis (Scx−/−) fail to properly form limb tendons, but the role that scleraxis has in regulating the growth and adaptation of tendons of adult organisms is unknown. To determine if scleraxis expression changes in response to a physiological growth stimulus to tendons, we subjected adult mice that express green fluorescent protein (GFP) under the control of the scleraxis promoter (ScxGFP) to a 6‐week‐treadmill training program designed to induce adaptive growth in Achilles tendons. Age matched sedentary ScxGFP mice were used as controls. Sclerax... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5212426 Mon, 12 Sep 2011 04:00:00 +0100 5212426 http://www.medworm.com/index.php?rid=5212425&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21551 AbstractWe performed this study to investigate the therapeutic role of vascular endothelial growth factor (VEGF) in medial collateral ligament (MCL) healing. Murine muscle derived stem cells (MDSCs) obtained via the preplate technique were retrovirally transduced to express: (1) VEGF and nLacZ (MDSC‐VEGF), (2) soluble fms‐like tyrosine kinase‐1 (sFLT1, a VEGF‐specific antagonist) and nLacZ (MDSC‐sFLT1), and (3) nLacZ (MDSC‐nLacZ). After transecting the MCL of immunodeficient rats, 5 × 105 cells of each of the transduction groups list above were transplanted into the MCL injury site. A control group was injected with phosphate‐buffered saline (PBS) only. Immunohistochemical staining demonstrated that there were more Isolectin B4 and β‐galactosidase double positive ce... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5212425 Mon, 12 Sep 2011 04:00:00 +0100 5212425 http://www.medworm.com/index.php?rid=5212424&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21555 AbstractPMMA particles released from bone implants are considered major contributor to osteolysis and subsequent implant failure. Although the ensuing inflammatory response has been described, the mechanisms underlying PMMA particulate‐induced osteolysis remain enigmatic. In previous studies, we have established that activation of Nuclear factor kappa‐B (NF‐κB) and MAP kinase pathways plays a central role in the pathogenesis of inflammatory osteolysis. Specifically, we have shown that impeding IKK complex assembly, and thus subsequent NF‐κB activation, dampens particle‐induced osteolysis. The IKK complex consists of IKKα, IKKβ, and IKKγ, also known as NEMO. NEMO has no catalytic activity and serves as a scaffold protein facilitating assembly and distal activation of NF‐κB... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5212424 Mon, 12 Sep 2011 04:00:00 +0100 5212424 http://www.medworm.com/index.php?rid=5212423&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21557 In this study, we clarified the effective size of HA oligosaccharides required to inhibit cell growth in the highly invasive breast cancer cell line, MDA‐MB‐231 cells. Based on the results of cell growth assay, we subsequently analyzed the effects of HA tetrasaccharides, HA decasaccharides, and high molecular weight HA on the other breast cancer cell behaviors in vitro and breast cancer bone metastasis in vivo. HA decasaccharides significantly inhibited cell growth, motility, and invasion, whereas tetrasaccharides did not. HAS2 mRNA expression was altered after the treatment with both tetrasaccharides and decasaccharides. Phosphorylation of Akt was suppressed after 1 h treatment with HA decasaccharides, and the effect was partially reversed by anti‐CD44 monoclonal antibody. In vivo... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5212423 Mon, 12 Sep 2011 04:00:00 +0100 5212423 http://www.medworm.com/index.php?rid=5198331&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21544 AbstractIt is important to know the magnitude and patterns of joint loading in people with knee osteoarthritis (OA), since altered loads are implicated in onset and progression of the disease. We used an EMG‐driven forward dynamics model to estimate joint loads during walking in a subject with knee OA and a healthy control subject. Kinematic, kinetic, and surface EMG data were used to predict muscle forces using a Hill‐type muscle model. The muscle forces were used to balance the frontal plane moment to obtain medial and lateral condylar loads. Loads were normalized to body weight (BWs) and the mean of three trials taken. The OA subject had greater medial and lower lateral loads compared to the control subject. Seventy‐five to 80% of the total load was borne on the medial compartment... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5198331 Thu, 08 Sep 2011 00:16:38 +0100 5198331 http://www.medworm.com/index.php?rid=5198332&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21543 This study demonstrated that Ag ions can be incorporated into a HA coating using an electrochemical technique. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5198332 Tue, 06 Sep 2011 23:00:00 +0100 5198332 http://www.medworm.com/index.php?rid=5186186&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21547 AbstractThe subsynovial connective tissue (SSCT) in the carpal tunnel may play a role in the etiology of carpal tunnel syndrome (CTS), yet the material properties of the SSCT remain unclear. Thus, we investigated the mechanical response of the SSCT in a rabbit model. Twenty‐four rabbit cadaver paws were used for mechanical testing; two paws were used for scanning electron microscopy (SEM) imaging. After testing normal tendon excursion, the divided third digit flexor digitorum superficialis (FDS) tendon was pulled to displacements of 2, 3.5, 5, or 8 mm, maintained at that position until force decay, and then the process was repeated. Normal excursion of the FDS averaged 4.8 mm. The ratio of the second peak force to the first peak force in the 2 mm group was 0.98 (SD = 0.16), whi... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5186186 Sat, 03 Sep 2011 19:20:27 +0100 5186186 http://www.medworm.com/index.php?rid=5186187&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21546 AbstractTenotomy of the long head of the biceps tendon (LHBT) is gaining popularity in shoulder surgery. We evaluated biomechanical and histological changes after tenotomy in a rabbit LHBT tenotomy model to confirm that autotenodesis is a phenomenon that occurs after the procedure. Twenty‐three rabbits were included. The right shoulder was harvested from 10 randomly selected rabbits. The shoulders were tested to determine the pullout strength of LHBT at the bicipital groove immediately after being tenotomized. The left shoulder of three of these rabbits also underwent histological analysis. The other 13 rabbits underwent LHBT tenotomy (tenotomy model). Six weeks post‐operatively, 10 were assigned for biomechanical study, and three underwent histological analysis. The pullout strength a... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5186187 Thu, 01 Sep 2011 23:00:00 +0100 5186187 http://www.medworm.com/index.php?rid=5186188&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21545 AbstractAn abnormal flexor moment pattern is often evident following total knee replacement (TKR) surgery. We investigated whether such a pattern at 12 months post‐surgery could be predicted using biomechanical gait measures assessed before surgery and at 4 months post‐surgery. Thirty two TKR patients were evaluated and classified as normal (biphasic pattern) or abnormal (flexor moment pattern) at each time point. Biomechanical parameters collected before surgery and at 4 months post‐surgery were then explored for their ability to predict gait patterns at 12 months post‐surgery. The gait pattern at 4 months was significantly associated with the 12 month post‐surgery gait pattern, with over half of those with a flexor moment pattern at 4 months retaining this pattern at 12 months.... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5186188 Wed, 31 Aug 2011 23:00:00 +0100 5186188 http://www.medworm.com/index.php?rid=5176762&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21541 In conclusion, we demonstrated the effect of cartilage fragments from osteoarthritic knee in promoting chondrogenic differentiation of MSCs. This may be a favorable strategy for MSC chondrogenesis without exogenous growth factor induction. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5176762 Tue, 30 Aug 2011 19:53:15 +0100 5176762 http://www.medworm.com/index.php?rid=5176763&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21540 AbstractThe patellofemoral (PF) joint plays an essential role in knee function, but little is known about the in vivo loading conditions at the joint. We hypothesized that the forces at the PF joint exceed the tibiofemoral (TF) forces during activities with high knee flexion. Motion analysis was performed in two patients with telemetric knee implants during walking, stair climbing, sit‐to‐stand, and squat. TF and PF forces were calculated using a musculoskeletal model, which was validated against the simultaneously measured in vivo TF forces, with mean errors of 10% and 21% for the two subjects. The in vivo peak TF forces of 2.9–3.4 bodyweight (BW) varied little across activities, while the peak PF forces showed significant variability, ranging from less than 1 BW during walking ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5176763 Mon, 29 Aug 2011 23:00:00 +0100 5176763 http://www.medworm.com/index.php?rid=5164908&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21542 The objective of this study was to evaluate the differential healing response in tendon at two distinct stages of development through mechanical, compositional, and structural properties. To accomplish this, a new in vivo surgical model and mechanical analysis method for the neonatal mouse Achilles tendons were developed. We demonstrated that injury during early development has an accelerated healing response when compared to injury during late development. This accelerated healing model can be used in future mechanistic studies to elucidate the method for improved adult tendon healing. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5164908 Sat, 27 Aug 2011 19:41:20 +0100 5164908 http://www.medworm.com/index.php?rid=5148769&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21526 This study aimed to compare the influence of Co–Cr and UHMWPE particles on the persistence of infection. Bioluminescent Staphylococcus aureus Xen36 were injected in air pouches prepared in subcutaneous tissue of immuno‐competent BALB/c mice (control), as a model for the joint space, in the absence or presence of Co–Cr or UHMWPE particles. Bioluminescence was monitored longitudinally up to 21 days, corrected for absorption and reflection by the particles and expressed relative to the bioluminescence found in the presence of staphylococci only. After termination, air pouch fluid and air pouch membrane were cultured and histologically analyzed. Bioluminescence was initially lower in mice exposed to UHMWPE particles with staphylococci than in mice injected with staphylococci only, possib... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148769 Wed, 24 Aug 2011 19:51:08 +0100 5148769 http://www.medworm.com/index.php?rid=5148775&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21527 AbstractMineralized scaffolds are widely used as bone grafts with the assumption that bone marrow derived cells colonize and remodel them. This process is slow and often unreliable so we aimed to improve the biocompatibility of bone grafts by pre‐seeding them with human mesenchymal stem cells from either bone marrow or dental pulp. Under standard cell culture conditions very low number of seeded cells remained on the surface of freeze‐dried human or bovine bone graft or hydroxyapatite. Coating the scaffolds with fibronectin or collagen improved seeding efficiency but the cells failed to grow on the surface until the 18th day. In contrast, human albumin was a very potent facilitator of both seeding and proliferation on allografts which was further improved by culturing in a rotating bio... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148775 Sun, 21 Aug 2011 23:00:00 +0100 5148775 http://www.medworm.com/index.php?rid=5148774&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21531 AbstractLocal antibiotic diffusion in rabbit femurs from two new PMMA‐based and nail‐shaped composites, enriched with β‐tricalcium phosphate (P‐TCP) and BaSO4 or only with BaSO4 (P‐BaSO4), and soaked in a solution of gentamicin (G) and vancomycin (V) was studied. Nails were implanted into the intramedullary cavity of healthy and osteomyelitic femurs to study the resolution of infection and to quantify the antibiotic penetration into bone by microbiological, pharmacological, and histological tests. A significant progression of osteomyelitis was recorded 7 weeks after MRSA inoculation, whereas no bacteria were found in animals treated with antibiotic‐loaded nails as confirmed by microbiology and histology (Smeltzer score). The release of both antibiotics from composites was high... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148774 Sun, 21 Aug 2011 23:00:00 +0100 5148774 http://www.medworm.com/index.php?rid=5148773&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21534 This study evaluated the regenerative capacity of degenerated nucleus pulposus (NP) cells obtained from patients undergoing anterior interbody fusions by measuring metabolic activity, DNA content, glycosaminoglycan (GAG) content, and cellular phenotype using qRT‐PCR profiling with a custom array of 42 genes. NP cells were cultured in alginate for 7 days with 4 treatment groups: transforming growth factor beta 3 (TGFβ3) + dexamethasone (Dex), soluble factors released from notochordal cells (NCs) cultured in alginate (NCA), soluble factors released from NCs in their native tissue environment (NCT), and basal media. TGFβ3 + Dex stimulated degenerated human NP cells to proliferate and exhibit an anti‐catabolic gene expression profile (with a decrease in ADAMTS5 and MMP1 compared ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148773 Sun, 21 Aug 2011 23:00:00 +0100 5148773 http://www.medworm.com/index.php?rid=5148772&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21536 AbstractChanges in intracellular calcium (Ca2+) concentration, also known as Ca2+ signaling, have been widely studied in articular cartilage chondrocytes to investigate pathways of mechanotransduction. Various physical stimuli can generate an influx of Ca2+ into the cell, which in turn is thought to trigger a range of metabolic and signaling processes. In contrast to most studies, the approach used in this study allows for continuous real time recording of calcium signals in chondrocytes in their native environment. Therefore, interactions of cells with the extracellular matrix (ECM) are fully accounted for. Calcium signaling was quantified for dynamic loading conditions and at different temperatures. Peak magnitudes of calcium signals were greater and of shorter duration at 37°C than at ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148772 Sun, 21 Aug 2011 23:00:00 +0100 5148772 http://www.medworm.com/index.php?rid=5148771&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21538 In this study, collagen content, orientation, collagen cross‐linking and spatial heterogeneity of all parameters was evaluated. Similar results were obtained when collagen content was evaluated with FTIR and PLM compared to the collagen content assessed with BA. Collagen content, orientation and collagen maturity increased significantly until the age of 3 months and remained similar thereafter. Simultaneously, spatial heterogeneity of the measured parameters decreased. Based on these findings, it seems that the collagen matrix of rabbit bone attains its mature state around 3 months of age, which is before the overall skeletal maturity is reached. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148771 Sun, 21 Aug 2011 23:00:00 +0100 5148771 http://www.medworm.com/index.php?rid=5148770&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21512 AbstractFemoral fractures within resurfacing implants have been associated with bone necrosis, possibly resulting from heat generated by cement polymerization. The amount of heat generated depends on cement mantle volume and type of cement. Using finite element analysis, the effect of cement type and volume on thermal necrosis was analyzed. Based on CT‐data of earlier implantations, two different models were created: a thick mantle model, representing a low‐viscosity “cement filling” technique, and a thin mantle model, representing a high viscosity “cement packing” technique. Six cement types were analyzed. The polymerization heat generation and its effect on bone necrosis were predicted. In the thin cement mantle models, no thermal necrosis was predicted. Thick cement mantle m... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148770 Sun, 21 Aug 2011 23:00:00 +0100 5148770 http://www.medworm.com/index.php?rid=5148777&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21529 This study compared the host response to human‐derived fascia lata ECM among various implantation sites in the rat model. Results showed that a xenograft in the rat shoulder does not exhibit a different host response at 7 days from xenograft in the body wall, suggesting that either site may be appropriate to study the early host response to biologic grafts as well as the effect of various treatments aimed to modify the early host response. By 28 days, a xenograft in the rat shoulder does elicit a unique host response from that seen in the body wall. Therefore, it may be more appropriate to use an orthotopic shoulder model for investigating the long‐term host response and remodeling of biologic grafts to be used for rotator cuff repair. © 2011 Orthopaedic Research Society. Published by... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148777 Thu, 18 Aug 2011 23:00:00 +0100 5148777 http://www.medworm.com/index.php?rid=5148776&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21530 AbstractSuture anchors and screws are commonly used for fixation of humeral greater tuberosity (GT) fractures in either arthroscopic or open surgeries, but no biomechanical studies have been performed to compare the strength of fixation constructs using these two implants. This cadaveric study aimed to compare the biomechanical strength of three different fixation constructs in the management of GT fractures: Double‐Row Suture Anchor Fixation (DR); Suture‐Bridge Technique using suture anchors and knotless suture anchors (SB); and Two‐Screw Fixation (TS). The experimental procedure was designed to assess fracture displacement after cyclic loading, failure load, and failure mode of the fixation construct. Significant differences were found among the SB (321 N), DR (263 N), and TS (... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148776 Thu, 18 Aug 2011 23:00:00 +0100 5148776 http://www.medworm.com/index.php?rid=5148782&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21535 The objective of the present study was to investigate the effects of heat stimulation and glutamine (Gln) on the expression of extracellular matrix genes and heat shock protein 70 (HSP70) in rat articular cartilage in vivo and to determine whether HSP70 expression achieved with a combination of microwave (MW) and Gln suppresses osteoarthritis (OA) progression in a rat OA model. Stimulation at 40 W was assumed to be appropriate in the present study, and the effects of heat treatment at this intensity were evaluated. Articular cartilage was collected at 8 h after heat stimulation and/or intraarticular Gln administration, and total RNA was extracted. The expression of HSP70, aggrecan, and type II collagen was quantified using real‐time RT‐PCR. Cartilage samples from the OA model were ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148782 Wed, 17 Aug 2011 23:00:00 +0100 5148782 http://www.medworm.com/index.php?rid=5148781&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21539 AbstractTo understand the potential mechanism for hand and wrist complaints in pipette users, whose motion is characterized by repetitive thumb motion in certain wrist positions, the peak (PGR) and mean (MGR) gliding resistance of the flexor pollicis longus (FPL) tendon were measured in nine human cadaver wrists. The PGR with the wrist in 30° ulnar deviation and in the neutral position were significantly lower than the PGR with the wrist in 60° flexion. The MGR with the wrist in 30° ulnar deviation was significantly lower than the MGR with the wrist in 60° flexion, 60° extension, or 20° radial deviation with 40° extension. Based on these data, we believe that a manual pipette designed to be used in neutral to ulnar deviated wrist position could have ergonomic advantages. © 2011 Ort... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148781 Wed, 17 Aug 2011 23:00:00 +0100 5148781 http://www.medworm.com/index.php?rid=5148780&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21528 AbstractThe meniscus plays an important role in controlling the biomechanics of the knee. However, the mechanical stress‐related response in meniscus cells remains unclear. We investigated mechanical stretch‐regulated gene expression in human meniscus cells. Human inner and outer meniscus cells were prepared from the inner and outer halves of the lateral meniscus. The gene expressions of Sry‐type HMG box (SOX) 9 and α1(II) collagen (COL2A1) were assessed by real‐time PCR analyses after cyclic tensile strain (CTS) treatment (0.5 Hz, 5% stretch). The localization and phosphorylation of SOX9 were evaluated by immunohistochemical and Western blot (WB) analyses. Chromatin immunoprecipitation (IP) analysis was performed to assess the stretch‐related protein–DNA complex formation b... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148780 Wed, 17 Aug 2011 23:00:00 +0100 5148780 http://www.medworm.com/index.php?rid=5148779&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21532 AbstractLow bone quality, such as induced by osteoporosis, is considered a main factor leading to failure of fracture fixations. Peri‐implant bone augmentation has been proposed as a means of reducing failure rates in osteoporotic bone by improving implant stability. The beneficial effects of pharmacological augmentation of bone in the immediate vicinity of the implant have been demonstrated. Yet, a quantitative understanding of the role of peri‐implant bone in implant stability is lacking. Therefore, the aim of our study was to quantify the effects of bone loss and peri‐implant bone augmentation on implant stability using image‐based finite element analyses. Using a validated model, we simulated how osteoporotic bone loss would affect implant stability in human humeral heads. We a... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148779 Wed, 17 Aug 2011 23:00:00 +0100 5148779 http://www.medworm.com/index.php?rid=5148778&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21533 AbstractThe effects of botulinum neurotoxin A on the passive mechanical properties of skeletal muscle have not been investigated, but may have significant impact in the treatment of neuromuscular disorders including spasticity. Single fiber and fiber bundle passive mechanical testing was performed on rat muscles treated with botulinum neurotoxin A. Myosin heavy chain and titin composition of single fibers was determined by gel electrophoresis. Muscle collagen content was determined using a hydroxyproline assay. Neurotoxin‐treated single fiber passive elastic modulus was reduced compared to control fibers (53.00 kPa vs. 63.43 kPa). Fiber stiffness and slack sarcomere length were also reduced compared to control fibers and myosin heavy chain composition shifted from faster to slower is... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5148778 Wed, 17 Aug 2011 23:00:00 +0100 5148778 http://www.medworm.com/index.php?rid=5121436&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21519 In conclusion, Xen29, Xen40, and especially Xen36, which had stable bioluminescent constructs, are feasible for long‐term in vivo monitoring of bacterial burden and biofilm formation to study chronic post‐arthroplasty infections and potential antimicrobial interventions. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res (Source: Journal of Orthopaedic Research) Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5121436 Fri, 12 Aug 2011 23:30:20 +0100 5121436 http://www.medworm.com/index.php?rid=5112217&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21510 AbstractSqueaking is a cause for concern in total hip arthroplasty (THA). However, the definition of this sound remains vague. Our goals were to characterize spectrally the squeaking in vitro under lubricated conditions and to compare the in vitro frequencies to in vivo frequencies. Four patients, who presented with a squeaking after ceramic‐on‐ceramic THA were investigated. In addition, 3 alumina ceramic 32 mm diameter components were tested in vitro under edge loading conditions using a friction simulator. Tests were conducted under lubricated conditions without and with the addition of a third body alumina particle. In vitro, no squeaking occurred under edge loading conditions. However, with the addition of a third body particle in the contact region, squeaking was obtained; the d... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5112217 Thu, 11 Aug 2011 06:40:32 +0100 5112217 http://www.medworm.com/index.php?rid=5112218&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21525 AbstractIn the present study the trabecular microstructural parameters (bone volume fraction, trabecular thickness, trabecular separation, trabecular number, connectivity density, degree of anisotropy, and structure model index) of the greater tubercle of the humeral head were measured for human healthy, human osteopenic, ovine, bovine, and porcine bones using micro‐computed tomography. Except for trabecular thickness and degree of anisotropy the values of the trabecular microstructural parameters generally differed significantly between species. Thus, only the species for which the implant is designed should be used for in vitro mechanical tests on the stability of implants in trabecular bone. Multivariate regression analysis showed that the microstructural parameters have similar princ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5112218 Tue, 09 Aug 2011 23:00:00 +0100 5112218 http://www.medworm.com/index.php?rid=5099399&cid=s_33779_31_f&fid=33779&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fjor.21521 AbstractAnimal models simulating osteoarthritis are frequently associated with irreversible changes in biomechanics. Although these models successfully induce osteoarthritis, results of experimental repair procedures are impaired by biomechanical problems. The aim of this study was to define the critical size of a chondral lesion to induce unicompartmental osteoarthritis in a stable joint. Sixteen sheep were randomly divided into four treatment groups. A cartilage defect (7‐ or 14‐mm diameter) was created in the weight‐bearing zone of the medial femoral condyle. The sheep were mobilized for 6 or 12 weeks. Osteoarthritis was determined by gross assessment, India ink staining, histology (Mankin score), and analysis of COMP in the serum. In the 6‐week group, only minor osteoarthritis ... Journal of Orthopaedic Research journals http://www.medworm.com/rss/comments.php?id=5099399 Sat, 06 Aug 2011 20:47:11 +0100 5099399