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 'Clinical Biomechanics' source. Sun, 21 Mar 2010 15:49:18 +0100 http://www.medworm.com/index.php?rid=3274471&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003310000392%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274471 Tue, 16 Feb 2010 15:04:23 +0100 3274471 http://www.medworm.com/index.php?rid=3274479&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002927%2Fabstract%3Frss%3Dyes This study introduces two novel outcomes that could be used to identify people with knee osteoarthritis from healthy controls. These outcomes examine the lengths of paths on a sphere derived from knee angle and knee position during gait.Methods: Participants with moderate knee osteoarthritis (n=47) and no knee pathology (n=51) walked overground. The time-varying orientation matrices and position vectors of the knee (leg relative to the thigh) were measured, then arclength (constant speed) parameterized. The orientation matrix column aligned with the long axis of the leg, and the tangent, normal and binormal vectors (Frenet Frame) along the position vectors were calculated. These unit length vectors all scribe paths (indicatrices) on a unit sphere. The path lengths of these indicatrices, fo... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274479 Wed, 20 Jan 2010 00:00:00 +0100 3274479 http://www.medworm.com/index.php?rid=3177688&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003310000070%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177688 Sat, 16 Jan 2010 14:51:13 +0100 3177688 http://www.medworm.com/index.php?rid=3274484&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002939%2Fabstract%3Frss%3Dyes Abstract: Background: For moderate-to-severe hallux valgus deformities with a 1–2 intermetatarsal angle in excess of 15°, a proximal first metatarsal osteotomy is indicated. The ideal osteotomy has yet to be defined, but should inherently limit the incidence of dorsal malunion and allow for early ambulation. The present study evaluates the mechanical integrity of two popular first metatarsal osteotomies.Methods: Ten matched pairs of fresh-frozen cadaveric first metatarsals were harvested. In one metatarsal from each pair, a Ludloff osteotomy was created and fixed with two cannulated 3.5mm screws. In the contralateral first metatarsal, a proximal chevron osteotomy was performed and subsequently fixed with a medially applied locking plate. All specimens were mounted within an Instron 1321... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274484 Mon, 11 Jan 2010 00:00:00 +0100 3274484 http://www.medworm.com/index.php?rid=3274478&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002873%2Fabstract%3Frss%3Dyes This study aimed at characterising such instability, and following it over time.Methods: We investigated treadmill walking in knee osteoarthritis, focusing on angular velocity of sagittal plane knee movements. Knee osteoarthritis patients were followed 1year after replacement surgery, and were compared to healthy peers. Subjects walked at increasing speeds, and maximum speed was registered. To quantify stability, we calculated short-term (λS) and long-term (λL) Lyapunov exponents (the exponential rate of divergence, in state space, of trajectories originating from nearest neighbours), as well as the variability of knee movements, the latter just after heel contact. At each measurement session, patients reported how often they had fallen in the preceding period.Findings: Patients had lowe... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274478 Mon, 11 Jan 2010 00:00:00 +0100 3274478 http://www.medworm.com/index.php?rid=3274480&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900285X%2Fabstract%3Frss%3Dyes Abstract: Background: Radiolucent lines and sclerotic margins are often seen on knee radiographs taken a year or longer after knee replacement surgery. Histology has shown that the radiolucent zone is predominantly fibrocartilage and the sclerotic margin is lamellar bone. The reasons for their existence are not clearly understood.Methods: A three-dimensional finite element model of the medial half of the proximal 75mm of a tibia implanted with a knee replacement was created and run over 365 iterations simulating 1year of in vivo post implant remodelling. After each iteration, new material properties were calculated for all elements of the model using established bone remodelling and tissue differentiation rules. For comparison with patient anteroposterior radiographs, “synthetic anteropo... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274480 Fri, 08 Jan 2010 00:00:00 +0100 3274480 http://www.medworm.com/index.php?rid=3274473&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002666%2Fabstract%3Frss%3Dyes Abstract: Background: People with tetraplegia often have extensive paralysis of the hand yet retain crude hand function. Their hand function is dependent on manipulating wrist position with the neurally-intact wrist extensor muscles to change the passive tension in paralysed thumb muscles. This moves the thumb in relation to the paralysed index finger enabling basic grasp. The aim of this study was to quantify the effect of wrist position on thumb flexor and adductor torques generated in paralysed hands of people with tetraplegia.Methods: Thumb flexor and adductor torques were measured as the wrist was passively moved from a fully flexed to a fully extended position in 10 people with tetraplegia who had paralysis of all thumb muscles. The relationships between thumb torques and wrist angle... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274473 Fri, 25 Dec 2009 00:00:00 +0100 3274473 http://www.medworm.com/index.php?rid=3274474&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002654%2Fabstract%3Frss%3Dyes Abstract: Background: Research into the multi-segmental mobility of the torso could add to our understanding of the contributions of the head and torso to human movement. The purpose of this study was to determine the motion and temporal coordination of the head and multiple torso segments during the sit-to-stand task.Methods: Thirty-two young, healthy participants performed five trials of the sit-to-stand movement and 6s of sitting. Range of motion and patterns of peak flexion and extension of six segments and joints and cross correlation of pairs of the six torso segments were analyzed from 3-D kinematic data.Findings: Sagittal range of motion for torso joints during the sit-to-stand task was greater than during sitting trials; motion at the lumbar/pelvis joint was greater than at other ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274474 Mon, 21 Dec 2009 00:00:00 +0100 3274474 http://www.medworm.com/index.php?rid=3274483&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002630%2Fabstract%3Frss%3Dyes Abstract: Background: Although foot orthotics are widely prescribed for the treatment of flatfoot, the biomechanical effects of such devices are not yet fully clear. Accordingly, this study conducted an experimental investigation to evaluate the effects of orthoses on the gait patterns of patients with flatfoot during level walking.Methods: Eleven adults with flatfoot deformities were recruited. For each participant, kinematic and kinetic data were measured under three test conditions, i.e. walking barefoot, walking with shoes, and walking with shoes and insoles. During each test, the participants’ gaits patterns were recorded and analyzed using a motion analysis system, two Kistler force plates and EVaRT software.Findings: The results showed that walking with shoes and insoles and walki... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274483 Wed, 16 Dec 2009 00:00:00 +0100 3274483 http://www.medworm.com/index.php?rid=3274481&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002617%2Fabstract%3Frss%3Dyes This study describes a multi-center retrospective review of existing motion analysis data (n=153 from three centers). Roll-over shapes were calculated by transforming center of pressure data from a laboratory-based coordinate system into two body-based coordinate systems. Roll-over shapes were then characterized using a circular arc model. Best-fit radii of roll-over shapes for children in three age groups (3–7years, 8–11years, and 12–17years) were compared using the Kruskal–Wallis test.Findings: No significant changes were found in roll-over shape radii between the three age groups (P=0.54 for ankle–foot roll-over shape radii; P=0.12 for knee–ankle–foot roll-over shape radii). The weighted mean of median radii for ankle–foot and knee–ankle–foot roll-over shapes from th... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274481 Wed, 16 Dec 2009 00:00:00 +0100 3274481 http://www.medworm.com/index.php?rid=3087402&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002678%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087402 Tue, 15 Dec 2009 14:56:50 +0100 3087402 http://www.medworm.com/index.php?rid=3087386&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002691%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087386 Tue, 15 Dec 2009 14:56:48 +0100 3087386 http://www.medworm.com/index.php?rid=3274482&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002605%2Fabstract%3Frss%3Dyes Abstract: Background: Ankle sprains are one of the most common lower extremity injuries. Real time human motion tracking is an accurate, inexpensive and portable system to obtain kinematic and kinetic measurements. The purpose of this study was to discriminate between subjects with chronic ankle instability and subjects with stable ankles through inertial tracking technology and force plates.Methods: Twelve subjects (mean (SD) 23.16 (5.32) years, 174.83 (8.78) cm, 73.58 (17.10) kg) with stable ankles and 13 (mean (SD) 24.69 (5.91) years, 173.31 (9.07) cm, 69.61 (15.32) kg) with chronic ankle instability performed the Star Excursion Balance Test. Time–frequency information based on wavelet decomposition was used for analysing all signals.Findings: Dynamic balance impairment associated wit... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274482 Mon, 14 Dec 2009 00:00:00 +0100 3274482 http://www.medworm.com/index.php?rid=3274477&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002629%2Fabstract%3Frss%3Dyes Abstract: Background: High risk of cartilage degeneration and premature osteoarthritis development has been clinically observed in anterior cruciate ligament (ACL) deficient knees. The risk has not been significantly reduced even after ACL reconstructive surgery. It was hypothesized that three-dimensional knee joint kinematics has been altered after ACL injury, and the biomechanical alteration has not been fully restored to a normal level after reconstructive surgery.Methods: Spatiotemporal parameters and three-dimensional knee joint rotations and translations were measured in ACL-deficient, ACL-reconstructed, and ACL-intact knees during level walking. The variables were compared between the ACL-deficient and ACL-intact knees, as well as between the ACL-reconstructed and ACL-intact knees.F... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274477 Mon, 14 Dec 2009 00:00:00 +0100 3274477 http://www.medworm.com/index.php?rid=3274475&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002642%2Fabstract%3Frss%3Dyes Abstract: Background: The hip joint center is a fundamental landmark in the identification of lower limb mechanical axis; errors in its location lead to substantial inaccuracies both in joint reconstruction and in gait analysis. Actually in Computer Aided Surgery functional non-invasive procedures have been tested in identifying this landmark, but an anatomical validation is scarcely discussed.Methods: A navigation system was used to acquire data on eight cadaveric hips. Pivoting functional maneuver and hip joint anatomy were analyzed. Two functional methods – both with and without using the pelvic tracker – were evaluated: specifically a sphere fit method and a transformation techniques. The positions of the estimated centers with respect to the anatomical center of the femoral head, ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274475 Mon, 14 Dec 2009 00:00:00 +0100 3274475 http://www.medworm.com/index.php?rid=3177694&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900254X%2Fabstract%3Frss%3Dyes This study underlines the need to consider age, obesity and gender when utilizing anthropometric data sets. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177694 Fri, 11 Dec 2009 00:00:00 +0100 3177694 http://www.medworm.com/index.php?rid=3274476&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002599%2Fabstract%3Frss%3Dyes Abstract: Background: Although weight bearing lunge exercises are frequently employed during anterior cruciate ligament and posterior cruciate ligament rehabilitation, cruciate ligament tensile forces are currently unknown while performing forward and side lunge exercises with and without a stride.Methods: Eighteen subjects used their 12 repetition maximum weight while performing a forward lunge and side lunge with and without a stride. A motion analysis system and biomechanical model were used to estimate cruciate ligament forces during lunging as a function of 0–90° knee angles.Findings: Comparing the forward lunge to the side lunge across stride variations, mean posterior cruciate ligament forces ranged between 205 and 765N and were significantly greater (P (Source: Clinical Biomecha... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274476 Thu, 10 Dec 2009 00:00:00 +0100 3274476 http://www.medworm.com/index.php?rid=3274472&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002575%2Fabstract%3Frss%3Dyes Abstract: Background: In massive rotator cuff tears a teres major (TMj) tendon transfer to the insertion of the supraspinatus (SSp) reverses its adduction moment arm into abduction which is supposed to be an adequate salvage procedure. Analysis of muscle function to find biomechanical ground of such success is scarce.Methods: We compared pre- and postoperative clinical outcome of TMj transfer, i.e. Range of Motion, pain, Constant Shoulder scores and arm force. TMj activation was evaluated in 14 patients suffering massive cuff tears using activation ratios to describe the desired ‘in-phase’ and undesired ‘out-of-phase’ contribution to the external arm moment. Additionally, we analyzed activation of the latissimus dorsi (LD) and the medial part of the deltoids (DE). The activation ra... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3274472 Thu, 10 Dec 2009 00:00:00 +0100 3274472 http://www.medworm.com/index.php?rid=3177691&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002496%2Fabstract%3Frss%3Dyes Abstract: Background: Lumbosacral orthoses (LSOs) are class I medical devices that are used in conservative and postoperative management of low back pain. The effectiveness of LSOs depends on their design aimed at enhancing trunk stiffness. Therefore, the purpose of this study was to compare two lumbar supports: extensible (made of neoprene and lycra) and non-extensible (made of polyester and nylon).Methods: Trunk stiffness and damping was estimated from trunk displacement data in response to a quick force release in trunk flexion, extension, and lateral bending. Fourteen male and 6 female subjects performed five trials at each experimental condition: (1) No LSO, (2) extensible LSO, (3) non-extensible LSO, (4) non-extensible LSO with a small rigid front panel, and (5) non-extensible LSO wi... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177691 Thu, 10 Dec 2009 00:00:00 +0100 3177691 http://www.medworm.com/index.php?rid=3177703&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002551%2Fabstract%3Frss%3Dyes Abstract: Background: Whole body vibration has recently been used as a therapeutic intervention for the treatment of children with disabling conditions. Researchers of these studies observed encouraging results; however, children may not be capable of attenuating high vibration accelerations to the head because of low mass. The purpose of this study was to determine if children transmit vibration differently than adults while standing on a vibration platform.Methods: The experimental protocol required 11 children and 10 adults to stand on a commercially available vibration platform at progressively greater frequencies (28, 33, and 42Hz). Transmissibility of vibration to various skeletal landmarks was assessed with a high speed motion analysis system.Findings: Transmissibility in children w... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177703 Mon, 30 Nov 2009 00:00:00 +0100 3177703 http://www.medworm.com/index.php?rid=3177699&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002502%2Fabstract%3Frss%3Dyes Abstract: Background: Recognized failure mechanisms after revision total knee arthroplasty include failure of fixation, instability and loosening. Thus, extended stems have been used to improve fixation and stability. In clinical cases where the stem is only applied in the femur, a question concerning the structural aspect of tibia may arise: Does a stemmed femur changes the structural behaviour of proximal tibia? It seems, that question has not yet been fully answered and the use of stems in the opposite bone structure requires further analysis.Methods: Proximal cortex strains were measured with tri-axial strain gauges in synthetic tibias for three different types of implanted femurs, with two constrained implants. To assess the strains at the cancellous bone under the tibial tray, it was... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177699 Mon, 30 Nov 2009 00:00:00 +0100 3177699 http://www.medworm.com/index.php?rid=3177690&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002526%2Fabstract%3Frss%3Dyes Abstract: Background: Electrophysiological criteria that identify and characterize low back pain can lead to better understanding of the afliction and possibly aid in its treatment.Method: Nineteen male and 22 female subjects with chronic back pain, without lumbar radiculopathy; and 30 male and 33 female control subjects with no history of low back pain in the last 12months, were recruited into the study. All subjects flexed, extended, laterally flexed, flexed anterolaterally and extended posterolaterally isometrically to 20% and 100% of their maximal voluntary contraction (MVC). Additionally, patients were asked to do these activities to their pain threshold levels and control subjects to 60% maximum voluntary contraction. Surface electromyograms (EMG) were recorded from lumbar erectores ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177690 Mon, 30 Nov 2009 00:00:00 +0100 3177690 http://www.medworm.com/index.php?rid=3177695&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002484%2Fabstract%3Frss%3Dyes Abstract: Background: Glenohumeral ligaments play an important role in stabilizing the shoulder. However, it is impossible to know how they function in vivo during shoulder motion. To help elucidate this stabilizing role, we studied the in vivo three-dimensional kinematics of the normal shoulder joint using a markerless bone-registration technique.Methods: Our technique utilized image registration to determine corresponding relations between several image volumes represented at different coordinates. Magnetic resonance images of 14 shoulder joints of seven healthy volunteers were acquired for seven isometric abduction orientations between 0° and 180°. We then calculated three-dimensional shortest path between the origin and insertion of each ligament based on anatomical study in each abd... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177695 Fri, 27 Nov 2009 00:00:00 +0100 3177695 http://www.medworm.com/index.php?rid=3177702&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002514%2Fabstract%3Frss%3Dyes This study indicates that in the long run there are no significant consequences, radiologically or biomechanically, of deep freezing as compared to fresh bone grafts. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177702 Mon, 23 Nov 2009 00:00:00 +0100 3177702 http://www.medworm.com/index.php?rid=3177701&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002460%2Fabstract%3Frss%3Dyes Abstract: Background: Wires and cables have been used extensively for spinal sublaminar wiring, but damages to the spinal cord due to compression by metal wires have been reported. We have used more flexible ultra-high-molecular-weight polyethylene cable (Tekmilon tape) instead of metal wires since 1999 and have obtained good clinical outcomes. Although the initial strength of Tekmilon tape is equivalent to metal wires, the temporal changes in the strength of Tekmilon tape in the body should be investigated to show that sufficient strength is maintained over time until bone union is complete.Methods: Tekmilon tape was embedded into the paravertebral muscle of 10-week-old male Japanese white rabbits. Samples were embedded for 0, 1, 3, 6 or 12months. At the end of each period, sequential str... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177701 Mon, 23 Nov 2009 00:00:00 +0100 3177701 http://www.medworm.com/index.php?rid=3177698&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002538%2Fabstract%3Frss%3Dyes Abstract: Background: Previous investigators have reported that long term eccentric cycling increases muscle size and strength in a variety of populations. The joint-specific strategies used to absorb power during eccentric cycling, however, have not been identified. The purpose of this investigation was to determine the extent to which ankle, knee, and hip joint actions absorb power during eccentric cycling.Methods: Eight active males resisted the reverse moving pedals of an isokinetic eccentric ergometer (60rpm) while targeting 20% of their maximum concentric cycling power. Pedal reaction forces and joint kinematics were recorded with an instrumented pedal and instrumented spatial linkage system, respectively. Joint powers were calculated using inverse dynamics; averaged over complete cr... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177698 Mon, 23 Nov 2009 00:00:00 +0100 3177698 http://www.medworm.com/index.php?rid=3177689&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002563%2Fabstract%3Frss%3Dyes Abstract: Background: The biomechanical role of the posterior spinal ligaments for spinal stability has been stated in previous studies. The investigation of the viscoelastic properties of human lumbar spinal ligaments is essential for the understanding of physiological differences between healthy and degenerated tissues. The stress-relaxation behavior of biological tissues is commonly described with the quasi-linear viscoelastic model of Fung, which assumes that the stress-relaxation response is independent of the applied strain. The goal of this study was to investigate the stress-relaxation response of ovine posterior spinal ligaments at different elongations to verify the above-mentioned hypothesis.Methods: Twenty-four ovine lumbar spinal segments, consisting of only the supraspinous a... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177689 Mon, 23 Nov 2009 00:00:00 +0100 3177689 http://www.medworm.com/index.php?rid=3177700&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002459%2Fabstract%3Frss%3Dyes Abstract: Background: In order to reduce the complications of bone cement, many efforts are underway to replace bone cement augmentation with cancellous bone granule augmentation for treating compression fractures of osteoporotic vertebral bodies. The goal of this study was to investigate the biomechanical effects of cancellous bone granule augmentation of Optimesh and polymethylmethacrylate augmentation of kyphoplasty on treated and adjacent non-treated vertebral bodies.Methods: Three-dimensional, anatomically detailed finite element models of the L1–L2 functional spinal unit were developed on the basis of cadaver computed tomography scans. The material properties and plug forms of the L2 centrum were adapted to simulate osteoporosis, cancellous bone granule and polymethylmethacrylate a... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177700 Wed, 18 Nov 2009 00:00:00 +0100 3177700 http://www.medworm.com/index.php?rid=3177697&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002472%2Fabstract%3Frss%3Dyes This study utilises a rarely examined biomechanical parameter – the free vertical moment to determine age-related differences in rotational kinetics of the body about the vertical-axis when stepping down from a stationary position.Methods: Ten older and 10 young adults completed step-downs from three heights. Free vertical moment impulse and peak during step-initiation double-support and the subsequent step-execution phase, and vertical-axis pelvis angular displacement and velocity at instant of landing were compared.Findings: The free vertical moment during double-support was directed away from the intended lead-limb side, producing a change in vertical-axis rotational momentum that moved the lead-limb in a forwards-medial direction about the stationary support/trailing limb during the ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177697 Wed, 18 Nov 2009 00:00:00 +0100 3177697 http://www.medworm.com/index.php?rid=3177696&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002447%2Fabstract%3Frss%3Dyes Abstract: Background: It has been proposed that female athletes who limit knee and hip flexion during athletic tasks rely more on the passive restraints in the frontal plane to deceleration their body center of mass. This biomechanical pattern is thought to increase the risk for anterior cruciate ligament injury. To date, the relationship between sagittal plane kinematics and frontal plane knee motion and moments has not been explored.Methods: Subjects consisted of 58 female club soccer players (age range: 11–20years) with no history of knee injury. Kinematics, ground reaction forces, and surface electromyography were collected while each subject performed a drop landing task. Subjects were divided into two groups based on combined sagittal plane knee and hip flexion angles during the de... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177696 Mon, 16 Nov 2009 00:00:00 +0100 3177696 http://www.medworm.com/index.php?rid=3177693&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002411%2Fabstract%3Frss%3Dyes The objectives of this study were to determine the effect of a Pilates training program on arm–trunk posture, strength, flexibility and biomechanical patterns during a functional shoulder flexion task.Methods: Nineteen subjects (9 controls, 10 experimental) were assessed twice, 12weeks apart, during which the experimental group was submitted to a Pilates training program (two 1-h sessions per week). The assessment consisted of trials of seated posture, abdominal strength, shoulder range of motion, and maximal shoulder flexion, during which neck, shoulder and trunk kinematics and the activity of 16 muscles were recorded.Findings: After training, subjects showed smaller static thoracic kyphosis during quiet sitting and greater abdominal strength. The experimental group also showed reduced ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177693 Mon, 02 Nov 2009 00:00:00 +0100 3177693 http://www.medworm.com/index.php?rid=3177692&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002253%2Fabstract%3Frss%3Dyes Abstract: Background: Ultrasound imaging is a valuable tool which, when applied appropriately, has the potential to provide information regarding the mechanics of abdominal muscle contraction. Typically, changes in muscle thickness are obtained and interpreted. However, the link between ultrasound measures of muscle thickening and EMG measures of activation is not clear.Methods: Five healthy males performed a series of abdominal muscle contractions while surface EMG and trunk posture were monitored and ultrasound images of the internal oblique and external oblique were captured both at relaxation and upon contraction. Ramped isometric flexor and extensor moment contractions were also assessed and compared between EMG and ultrasound.Findings: No definitive relationship between increases in ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3177692 Mon, 02 Nov 2009 00:00:00 +0100 3177692 http://www.medworm.com/index.php?rid=3087394&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002265%2Fabstract%3Frss%3Dyes This study explored the effects of graft density and cement penetration on stem motion using a finite element model that was validated against experimental data.Findings: Cement penetration has a considerable stabilizing effect on stem motion, whereas graft density is important only when there is no cement–endosteum contact. Stem migration can be attributed primarily to slippage at the endosteum and stem–cement interfaces rather than to shear failure within the graft.Interpretation: Partial cement penetration to the endosteum increases the likelihood of meeting clinical requirements of early implant stability, particularly when a dense graft bed cannot be achieved. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087394 Mon, 02 Nov 2009 00:00:00 +0100 3087394 http://www.medworm.com/index.php?rid=3087391&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002423%2Fabstract%3Frss%3Dyes Abstract: Background: Shoulder muscle overuse has been linked to the high prevalence of shoulder injuries in manual wheelchair users. Ramp ascent is a barrier that is often faced by manual wheelchair users that requires higher muscle activations than level wheelchair propulsion. Additionally, reported subjective measures of shoulder pain are reduced amongst manual wheelchair users when using a wheelchair wheel outfitted with a gear mechanism. The purpose of the current investigation was to investigate shoulder muscle activation levels and upper limb kinematics during ramp ascent with and without the use of a geared wheel.Methods: Thirteen healthy participants (6 male and 7 female) performed ramp ascent on four ramp grades (1:12, 1:10, 1:8, 1:6) using three wheel conditions (gear, no gear, ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087391 Mon, 02 Nov 2009 00:00:00 +0100 3087391 http://www.medworm.com/index.php?rid=3087387&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002241%2Fabstract%3Frss%3Dyes Abstract: Background: Back pain is the most frequently reported musculo-skeletal problem during pregnancy. High muscle fatigability has been associated with back pain in the general population. During pregnancy, the gradual increase in loads may have a training effect, increasing strength and endurance of back muscles. This adaptation however may be too slow, or insufficient to be significant in light of other changes during pregnancy.Methods: Thirty-two pregnant women performed a fatigue test which consisted of maintaining a fixed load of 70 Nm for 60 s while the surface EMG of the longissimus lumborum and multifidus muscles were recorded bilaterally at 14, 24 and 34weeks of pregnancy. The measure of fatigability was the highest absolute slope of the median frequency of the power spectrum... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087387 Mon, 26 Oct 2009 00:00:00 +0100 3087387 http://www.medworm.com/index.php?rid=3087400&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002228%2Fabstract%3Frss%3Dyes Abstract: Background: Posterior-cruciate ligament retaining total knee arthroplasty designs have long been used with excellent clinical success, but often have shown kinematics and flexion performance that are significantly different from the natural knee. The purpose of this study was to compare deep-flexion knee kinematics in patients with two types of posterior-cruciate ligament retaining total knee arthroplasty.Methods: One group received a traditional curved symmetric articular configuration, and one group received a design incorporating a lateral compartment which constrains the lateral condyle to the antero-posterior center of the tibial plateau in extension, but allows translation in flexion – roughly approximating the role of the anterior cruciate ligament. In vivo kinematics we... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087400 Fri, 23 Oct 2009 00:00:00 +0100 3087400 http://www.medworm.com/index.php?rid=3087392&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002216%2Fabstract%3Frss%3Dyes This study objectively measured scapular orientation and quantified its influence on shoulder muscle activity levels and hand force capabilities during vertical and horizontal manual exertions.Methods: Ten healthy male university students performed 24 exertions in combinations of scapular orientation (protracted, neutral and retracted), exertion direction (up, down, medial, lateral) and intensity (maximal or 40N). Scapular orientation was quantified using an acromion marker cluster method. An orientation by intensity repeated measures ANOVA identified differences in quantified scapular orientation. A two-way multivariate ANOVA identified the influence of scapular orientation and hand force direction on muscle activity and hand force capability.Findings: Participants assumed consistent retr... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087392 Thu, 22 Oct 2009 00:00:00 +0100 3087392 http://www.medworm.com/index.php?rid=2906940&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002381%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906940 Tue, 20 Oct 2009 13:57:37 +0100 2906940 http://www.medworm.com/index.php?rid=2906925&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002289%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906925 Tue, 20 Oct 2009 13:57:35 +0100 2906925 http://www.medworm.com/index.php?rid=3087401&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002204%2Fabstract%3Frss%3Dyes Abstract: Background: Recent studies suggest that the architecture of spastic muscles in children with cerebral palsy is considerably altered; however, only little is known about the structural changes that occur other than in the gastrocnemius muscle. In the present study, Magnetic Resonance Imaging (MRI) and subject-specific modelling techniques were used to compare the lengths and volumes of six lower limb muscles between children with cerebral palsy and typically developing children.Methods: MRI scans of the lower limbs of two children with spastic hemiplegia cerebral palsy, four children with spastic diplegia cerebral palsy (mean age 9.6 years) and a group of typically developing children (mean age 10.2 years) were acquired. Subject-specific models of six lower limb muscles were devel... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087401 Mon, 19 Oct 2009 00:00:00 +0100 3087401 http://www.medworm.com/index.php?rid=3087399&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002174%2Fabstract%3Frss%3Dyes Abstract: Background: While the application of compressive joint loads and thigh muscle activity are associated with anterior tibial translation in vitro, less is known during early load acceptance in vivo. We investigated the effects of increasing axial loads on anterior tibial translation and thigh muscle activity in healthy knees during transition from non-weight bearing to early weight bearing.Methods: Participants (11 males, 11 females) underwent 20%, 40%, and 60% body weight acceptance trials at 20° knee flexion while electromagnetic sensors measured anterior tibial translation (mm), and surface electromyography recorded quadriceps and hamstring muscle onset times (ms) and amplitudes (% maximal voluntary isometric contraction). Repeated measures ANOVA compared values across loads. P... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087399 Mon, 19 Oct 2009 00:00:00 +0100 3087399 http://www.medworm.com/index.php?rid=3087393&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002186%2Fabstract%3Frss%3Dyes The objective of this study was to compare varus–valgus laxity and failure properties of this new ulnar collateral ligament reconstruction to the intact ulnar collateral ligament.Methods: Nine matched pairs of cadaveric upper extremities were used, the intact ulnar collateral ligament as the control for the load to failure properties and the contralateral arm for ulnar collateral ligament reconstruction. Varus–valgus laxity was measured at 30°, 50°, 70°, and 90° of elbow flexion for intact, ulnar collateral ligament transected, and ulnar collateral ligament reconstruction. Ulnar collateral ligament reconstruction was performed using a tendon graft passed through a bone tunnel and looped around the medial column of the humerus without dissection of the ulnar nerve. Distally, the gra... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087393 Mon, 19 Oct 2009 00:00:00 +0100 3087393 http://www.medworm.com/index.php?rid=3087390&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900223X%2Fabstract%3Frss%3Dyes Abstract: Background: Based on the development of minimal-invasive techniques and introduction of new implants enabling secure reconstruction an increasing number of patients are treated by isolated anterior column surgery. Most biomechanical studies dealing with thoracolumbar fracture models use worst-case scenarios of complete corpectomies to simulate vertebral body defects neglecting the influence of remaining cortical bone in partial corpus instability. Using a standardized partial and total corpectomy model we investigated the effect of the extent of corpectomy on stiffness in an anterior reconstruction model.Methods: Twelve human thoracolumbar specimens (Th11-L3) were loaded in a spine simulator with pure moments in the three motion planes. Following intact testing partial corp- and ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087390 Mon, 19 Oct 2009 00:00:00 +0100 3087390 http://www.medworm.com/index.php?rid=3087396&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002198%2Fabstract%3Frss%3Dyes Abstract: Background: Joint motion studies suggest that adults have symmetrical hip rotation range of motion. Asymmetries in hip rotation are often related to lower extremity musculoskeletal conditions. The purpose of this study was to determine if muscle strength differences occur in subjects with symmetrical vs. asymmetrical hip rotation. We hypothesize that those with asymmetrical hip rotation will have less strength in the standard 0° test position when compared to a position where the joint is in its center or mid-position.Methods: Sixty-four subjects participated. Muscle strength was measured in the standard 0° and mid-range hip positions. Subjects were divided into three groups depending on hip rotation, symmetrical, internal rotation greater than external rotation and external ro... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087396 Thu, 15 Oct 2009 00:00:00 +0100 3087396 http://www.medworm.com/index.php?rid=3087388&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002162%2Fabstract%3Frss%3Dyes This study investigated the role of repeated dynamic axial torque/twist combined with repeated flexion on the disc herniation mechanism.Methods: Porcine cervical spines were tested in one of the following four testing protocols: flexion–extension only; axial torque/twist only; flexion–extension followed by axial torque/twist; or axial torque/twist followed by flexion–extension. Plane film radiographs and computed tomography with contrast in the nucleus were obtained at regular intervals during and following the mechanical testing process together with final dissection to determine the disc injury patterns.Findings: Axial torque/twist in combination with repetitive flexion extension motion, regardless of order, encouraged radial delamination within the annulus (67.5% of specimens). Al... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087388 Thu, 08 Oct 2009 00:00:00 +0100 3087388 http://www.medworm.com/index.php?rid=3087389&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002022%2Fabstract%3Frss%3Dyes Abstract: Background: In a previous study, ligaments that connect the extraforaminal lumbar spinal nerves with the fibrous capsule of the facet joints and the dorsolateral side of the intervertebral disc were described. This anatomical configuration suggests a mechanical role in transferring extraforaminal spinal nerve traction.Methods: One embalmed human lumbar spine was dissected from the twelfth thoracic vertebra to the first sacral vertebra to isolate the twelfth thoracic to the fourth lumbar spinal nerves. The spinal nerves from L1 to L4 were pulled at different angles with respect to the axis of the spine. Forces of 1–6N were applied. The displacements of reflective markers glued to the proximal and distal ends of the adjoining ligaments were recorded with a video system.Findings: ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087389 Mon, 28 Sep 2009 00:00:00 +0100 3087389 http://www.medworm.com/index.php?rid=2817345&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002149%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817345 Tue, 22 Sep 2009 17:06:01 +0100 2817345 http://www.medworm.com/index.php?rid=2817331&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002058%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817331 Tue, 22 Sep 2009 17:05:58 +0100 2817331 http://www.medworm.com/index.php?rid=3087397&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001995%2Fabstract%3Frss%3Dyes We examined how a soft shell hip protector affects the magnitude and distribution of force to the hip during simulated falls, and how the protective effect depends on the fall direction and the amount of soft tissue padding over the hip.Methods: Fourteen young women with either high or low body mass index participated in a “pelvis release experiment” that simulated falls resulting in either lateral, anterolateral or posterolateral impact to the pelvis with/without a soft shell hip protector. Outcome variables were the magnitude and location of peak pressure (d, theta) with respect to the greater trochanter, total impact force, and percent force applied to four defined hip regions.Findings: The soft shell hip protector reduced peak pressure by 70%. The effect was two times greater in lo... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087397 Tue, 22 Sep 2009 00:00:00 +0100 3087397 http://www.medworm.com/index.php?rid=2906932&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001946%2Fabstract%3Frss%3Dyes Abstract: Background: Falls are the leading cause of death in adults over 65years of age. Falls during turning are likely to result in costly and debilitating hip fractures. Two-thirds of adults who fracture a hip will never regain their previous level of independence. The purpose of this study, therefore, was to examine performance of turning in place in young and older adults.Methods: Ten young (mean age=25years) and 10 community-dwelling older adults (mean age=75years) performed a standing turning task under two conditions: feet constrained and feet unconstrained. Dependent measures were rotational range of motion of the head-on-trunk, trunk-on-pelvis, pelvis and feet; trunk flexion/extension and knee flexion; and center of pressure range and center of mass range in both the anterior–... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906932 Mon, 21 Sep 2009 23:00:00 +0100 2906932 http://www.medworm.com/index.php?rid=2906933&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001934%2Fabstract%3Frss%3Dyes Abstract: Background: Compared to matched controls, knee osteoarthritis patients walk with altered, kinematics, kinetics and muscle activity. Studies of osteoarthritis patient gait have focused on individual measures, and findings from these studies differ due to differences in patient levels of disability and age. Therefore, aims of this study were to examine kinematic, kinetic and muscle co-contraction gait variables within a single osteoarthritis patient group, and to determine if alterations in these variables are related to pain, symptom and function measures.Methods: Thirty asymptomatic controls and 54 patients with radiographic evidence of knee osteoarthritis participated. Self-perceived measures of pain and symptoms, and gait (knee joint angles, moments and muscle co-contraction) w... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906933 Thu, 17 Sep 2009 23:00:00 +0100 2906933 http://www.medworm.com/index.php?rid=3087398&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002009%2Fabstract%3Frss%3Dyes Abstract: Background: Increased mechanical load is one risk factor for osteoarthritis. One possible treatment for this disorder is the use of knee braces in order to redistribute joint loading, which may inhibit the progression of the disease. The hypothesis was: knee adduction moment can be reduced with the use of a dedicated knee orthosis, which applies an abduction moment at the knee.Methods: Sixteen healthy male subjects with varus alignment were analysed during walking and running while using an adjustable valgus orthosis. Peak knee adduction moments and knee adduction angular impulses were evaluated through inverse dynamics. Additionally, the abduction moment produced by the orthosis was measured in three different adjustments of valgus angulations (neutral, 4° and 8° valgus) using... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087398 Wed, 16 Sep 2009 00:00:00 +0100 3087398 http://www.medworm.com/index.php?rid=2906926&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309002010%2Fabstract%3Frss%3Dyes Abstract: Background: Hallux valgus and lesser toe deformities are highly prevalent foot problems in older people. One factor contributing to the development of these toe deformities is reduced toe flexor strength. As adequate toe flexor strength is also crucial in maintaining balance, it was hypothesised that poor toe flexor strength and toe deformities would increase the risk of falls in community-dwelling older people.Method: The feet of 312 men and women aged 60–90years were assessed for the presence of lesser toe deformities and hallux valgus. Hallux and lesser toe flexor strength were assessed using an emed AT-4 pressure platform and novel test protocol. Participants were then followed prospectively to determine their falls incidence over 12months.Findings: During the 12month follo... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906926 Sun, 13 Sep 2009 23:00:00 +0100 2906926 http://www.medworm.com/index.php?rid=3087395&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001983%2Fabstract%3Frss%3Dyes In this study, we investigated the effect of the stem roughness on the micromotion at the bone–cement and cement–implant interface and investigated cracks in the cement layer through in vitro measurement.Methods: Stems with the same shape and material but with different surface roughness (polished with Ra=0.05μm and matte-finished with Ra=0.83μm) were tested to measure the interface micromotion using custom-made sensors. The stems were implanted in five paired cadaver femurs and cyclic loading was applied to the femoral head to measure the interface micromotion. After loading, we measured the crack length and calculated the crack length density at the cement layer.Findings: The difference in the interface micromotion between the polished stem and the rough stem was not significant ex... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=3087395 Thu, 10 Sep 2009 00:00:00 +0100 3087395 http://www.medworm.com/index.php?rid=2906939&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001910%2Fabstract%3Frss%3Dyes Abstract: Background: A suggested link between ambulatory mechanics and injury development has resulted in significant interest the development of footwear to change locomotion patterns. The purpose of this study was to test the hypothesis that there will be significant changes in the kinematics and kinetics at the ankle and minimal changes at the knee and hip in the mechanics of running in a shoe with a sagittal plane curvature relative to a flat soled shoe.Methods: During running 3-D lower extremity kinematics and kinetics for 19 healthy volunteers were quantified using an optoelectronics system and a force plate. Data were collected for a flat sole conventional shoe (New Balance 658 (Control)) and a shoe with a rounded sole in the sagittal plane (Masai Barefoot Technologies (MBT)). Data... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906939 Wed, 09 Sep 2009 23:00:00 +0100 2906939 http://www.medworm.com/index.php?rid=2906937&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001971%2Fabstract%3Frss%3Dyes Abstract: Background: The technological advances that have been made in developing highly functional prostheses are promising for very active patients but we do not yet know whether they cause an increase in biomechanical load along with possibly negative consequences for pressure conditions in the socket. Therefore, this study monitored the socket pressure at specific locations of the stump when using a microprocessor-controlled adaptive prosthetic ankle under different walking conditions.Methods: Twelve unilateral transtibial amputees between 43 and 59years of age were provided with the Proprio-Foot™ (Össur) and underwent an instrumented 3D gait analysis in level, stair, and incline walking, including synchronous data capturing of socket pressure. Peak pressures and pressure time inte... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906937 Wed, 09 Sep 2009 23:00:00 +0100 2906937 http://www.medworm.com/index.php?rid=2906934&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001922%2Fabstract%3Frss%3Dyes Abstract: Background: High-flexion knee replacements have been developed to accommodate a large range of flexion (>120°) after total knee arthroplasty. Both posterior cruciate ligament retaining and sacrificing high-flexion knee designs have been marketed. The main objective of this study was to evaluate the biomechanical performance of a cruciate-retaining high-flexion knee replacement. Furthermore, the mechanical behaviour of this high-flexion knee replacement was compared to both a cruciate-retaining conventional and a posterior-stabilized high-flexion knee replacement.Methods: A finite element prosthetic knee model was developed to analyze the mechanical performance of the knee designs evaluated in this study. Polyethylene stresses and the amount of femoral rollback were studied durin... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906934 Sun, 06 Sep 2009 23:00:00 +0100 2906934 http://www.medworm.com/index.php?rid=2906929&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001892%2Fabstract%3Frss%3Dyes Abstract: Background: It has been previously shown that injury to the triangular fibrocartilage complex increases the moment arm of the extensor carpi ulnaris. This will reduce the force producing capacity of the muscle in some situations, but will also increase its mechanical advantage. It is also possible that the change in the tendon path may increase tendon friction, predisposing the patient to future repetitive motion injury. It is the purpose of this study to determine the effects of triangular fibrocartilage complex injury on extensor carpi ulnaris moment producing capacity and tendon friction.Methods: A simple simulation was used to examine muscle moment producing capacity throughout the range of motion, at varying speeds and in both injured and healthy states. Six fresh frozen hum... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906929 Sun, 06 Sep 2009 23:00:00 +0100 2906929 http://www.medworm.com/index.php?rid=2906931&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001739%2Fabstract%3Frss%3Dyes Abstract: Background: Falls are one of the greatest concerns among the elderly. Among a number of strategies proposed to reduce the risk of falls, improving muscle strength has been applied as a successful preventive strategy. Although it has been suggested as a relevant strategy, no studies have analyzed how muscle strength improvements affect the gait pattern. The aim of this study was to determine the effects of a lower limb strength training program on gait kinematics parameters associated with the risk of falls in elderly women.Methods: Twenty seven elderly women were assigned in a balance and randomized order into an experimental (n=14; age=61.1 (4.3)years, BMI=26.4 (2.8)kgm−2) and a control (n=13; age=61.6 (6.6)years; BMI=25.9 (3.0)kgm−2) group. The EG performed lower limb stren... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906931 Mon, 31 Aug 2009 23:00:00 +0100 2906931 http://www.medworm.com/index.php?rid=2906936&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001909%2Fabstract%3Frss%3Dyes This study provides evidence based on a cadaveric model that compression staples have a promising potential to treat transverse patella fractures. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906936 Thu, 27 Aug 2009 23:00:00 +0100 2906936 http://www.medworm.com/index.php?rid=2906938&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001740%2Fabstract%3Frss%3Dyes Abstract: Background: There is a lack of research into the relationship between obesity and muscle–tendon unit stiffness in postmenopausal women. Muscle–tendon unit stiffness appears to affect human motion performance and excessive and insufficient stiffness can increase the risk of bone and soft tissue injuries, respectively. The aim of this study was to investigate the relationship between muscle–tendon unit stiffness and obesity in postmenopausal women.Methods: 105 postmenopausal women (58 [SD 5.5] years) participated. Four groups (normal weight, pre-obese, obesity class I and obesity class II) were defined according World Health Organization classification of body mass index. The ankle muscle–tendon unit stiffness was assessed in vivo with a free oscillation technique using a l... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906938 Mon, 24 Aug 2009 23:00:00 +0100 2906938 http://www.medworm.com/index.php?rid=2906935&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001703%2Fabstract%3Frss%3Dyes Conclusions: These results suggest that dynamic measures slightly enhance the predictive strength of static measures when explaining variation in the knee adduction moment. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906935 Mon, 24 Aug 2009 23:00:00 +0100 2906935 http://www.medworm.com/index.php?rid=2906930&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001697%2Fabstract%3Frss%3Dyes Abstract: Background: Total hip replacement using a minimally invasive surgical approach is claimed to enable recovering of motor function more quickly. The purpose of this prospective As per the stylesheet, kindly provide section headings for abstract.and randomized study was to test this claim by evaluating early patient functional outcomes by gait analysis.Methods: Seventeen patients were operated on using a traditional anterolateral approach (AL), 16 using a minimally invasive direct anterior approach (DA). Gait analysis was performed the day before surgery, and at 6 and 12weeks after surgery. Time–distance and kinematics analyses were performed by a recently proposed anatomically-based gait analysis protocol. A static double-leg stance and five walking trials at self-selected speeds... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906930 Mon, 24 Aug 2009 23:00:00 +0100 2906930 http://www.medworm.com/index.php?rid=2906928&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001715%2Fabstract%3Frss%3Dyes Abstract: Background: Low back pain is often associated with increased spinal stiffness which thought to arise from increased muscle activity. Unfortunately, the association between paraspinal muscle activity and paraspinal stiffness, as well as the spatial distribution of this relation, is unknown. The purpose of this investigation was to employ new technological developments to determine the relation between spinal muscle contraction and spinal stiffness over a large region of the lumbar spine.Methods: Thirty-two male subjects performed graded isometric prone right hip extension at four different exertion levels (0%, 10%, 25% and 50% of the maximum voluntary contraction) to induce asymmetric back muscle activity. The corresponding stiffness and muscle activity over bilateral paraspinal l... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906928 Mon, 24 Aug 2009 23:00:00 +0100 2906928 http://www.medworm.com/index.php?rid=2906927&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001727%2Fabstract%3Frss%3Dyes Abstract: Background: Cumulative trauma disorder is commonly reported by workers engaged in prolonged repetitive/cyclic occupational activities. Recent experimental evidence confirms that relatively short periods of cyclic lumbar flexion at high loads result in substantial creep of viscoelastic tissues, prolonged periods of its recovery to baseline together with a neuromuscular disorder and exposure to instability. The biochemical process associated with the creep and neuromuscular disorder are not well explored. The purpose of the study is to identify the ligaments as one of the organs of failure and an acute inflammation as the result of failure as a preliminary step in the development of chronic inflammation that might lead to cumulative trauma disorder elicited by high magnitude cyclic... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2906927 Mon, 24 Aug 2009 23:00:00 +0100 2906927 http://www.medworm.com/index.php?rid=2817344&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001661%2Fabstract%3Frss%3Dyes Abstract: Background: Screws with strong pull-out strength have been sought for the treatment of cancellous bone. We hypothesized that an obliquely angled screw thread has advantages over conventional vertical thread with a minimal proximal half angle.Methods: Metal and bone screws were made of stainless steel and porcine cortical bone. Their proximal half angle was set at 0°, 30°, or 60°. The screws were inserted into porcine cancellous bone. At 0°, the thread faced the recipient bone vertically. Pullout tests at a rate of 30mm/min (n=40, each screw type) and microcomputed tomography (n=6) were conducted.Findings: The pull-out strength of the screws was maximal at 30°; 348.8 (SD, 44.1)N with metal and 326.6 (39.4)N with bone. It was intermediate at 0°; 301.9 (35.9)N with metal and 2... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817344 Mon, 24 Aug 2009 23:00:00 +0100 2817344 http://www.medworm.com/index.php?rid=2817343&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001685%2Fabstract%3Frss%3Dyes This study examined changes to the work of friction of the posterior tibial tendon under three conditions: intact, simulated flatfoot, and flatfoot with an orthosis. It was hypothesized that work of friction of the posterior tibial tendon would significantly increase in the flatfoot, yet return to normal with an orthosis. Changes to bone orientation were also expected.Methods: Six lower limb cadavers were mounted in a foot simulator, that applied axial and a posterior tibial tendon load. Posterior tibial tendon excursion, gliding resistance, and foot kinematics were monitored, and work of friction calculated. Each specimen moved through a range of motion in the coronal, transverse, and sagittal planes.Findings: Mean work of friction during motion in the coronal plane were 0.17Ncm (SD 0.07N... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817343 Mon, 24 Aug 2009 23:00:00 +0100 2817343 http://www.medworm.com/index.php?rid=2817335&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001612%2Fabstract%3Frss%3Dyes Abstract: Background: Diabetic sensorimotor polyneuropathy is a long-term diabetic complication. It is involved in the pathogenesis of the diabetic foot, which is a major cause of morbidity and mortality. The study aims to investigate the effects of diabetic polyneuropathy on gait and posture.Methods: Sixty seven subjects were enrolled: 21 diabetics without polyneuropathy, 26 with polyneuropathy, 20 controls (respectively, mean age 63.8 (SD 5.4), 63.2 (SD 5.6), 59.0 (SD 5.2) years, mean body mass index 26.3 (SD 2.5), 25.6 (SD 3), 24.0 (SD 2.9)). Postural and morphological evaluation and gait analysis were performed. Physical examination, together with a motion capture system synchronized with two force plates and two baropodometric systems were used. We evaluated lower limb mobility, foot ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817335 Mon, 24 Aug 2009 23:00:00 +0100 2817335 http://www.medworm.com/index.php?rid=2722223&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001855%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722223 Sat, 22 Aug 2009 10:48:49 +0100 2722223 http://www.medworm.com/index.php?rid=2722205&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001764%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722205 Sat, 22 Aug 2009 10:48:44 +0100 2722205 http://www.medworm.com/index.php?rid=2817339&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001673%2Fabstract%3Frss%3Dyes Abstract: Background: It is reported that a majority of the patients with knee osteoarthritis have cartilage degeneration in medial and patellofemoral compartments. A bi-compartmental knee replacement system was designed to treat osteoarthritis at medial and patellofemoral compartments. To date, there is very little information regarding the knee mechanics during gait after bi-compartmental knee replacement. The purpose of the study was to evaluate knee strength and mechanics during level walking after knee replacement.Methods: Ten healthy control subjects and eight patients with unilateral bi-compartmental knee replacement participated in the study. Maximal isokinetic concentric knee extension strength was evaluated. 3D kinematic and kinetic analyses were conducted for level walking. Pair... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817339 Wed, 19 Aug 2009 23:00:00 +0100 2817339 http://www.medworm.com/index.php?rid=2817334&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001624%2Fabstract%3Frss%3Dyes This study investigates balance instability in diabetic patients with and without peripheral neuropathy.Methods: Quiet standing balance was investigated using an accelerometric-based method in 24 diabetic patients (12 with and 12 without peripheral neuropathy) and compared with 12 control subjects. Accelerations were measured at lumbar and ankle levels using three accelerometers. Two standing conditions of 30s were evaluated (i.e., eyes opened, eyes closed). The range and root mean square values were calculated on the anterior posterior component of lumbar and ankle accelerations and for the medial lateral component of lumbar accelerations. Differences between parameters were compared between groups using ANOVA and post hoc comparisons.Findings: The diabetic patients with peripheral neurop... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817334 Sun, 16 Aug 2009 23:00:00 +0100 2817334 http://www.medworm.com/index.php?rid=2817341&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001570%2Fabstract%3Frss%3Dyes Abstract: Background: Movement variability may influence episodes of instability following lateral ankle sprain.Methods: Sixty-three recreational athletes with a history of moderate-severe ankle sprain were recruited. Mechanically and functionally unstable ankle groups had ⩾2 episodes of instability in the last year. Mechanically unstable had clinically lax lateral ankle ligaments; functionally unstable and copers did not. Copers had a history of sprain but no residual instability. Lower extremity 3-dimensional kinematics and ground reaction forces were measured during a 2-legged stop jump. Average ensemble curves of eight trials normalized to 100% of stance phase were created. The coefficient of variation and average standard deviation of the ensemble curves of each variable were identi... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817341 Wed, 12 Aug 2009 23:00:00 +0100 2817341 http://www.medworm.com/index.php?rid=2817342&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900165X%2Fabstract%3Frss%3Dyes This study examined the effects of ankle-foot orthoses on functional balance, static and dynamic weight-bearing asymmetry and dynamic balance control of the paretic and non-paretic lower limbs.Methods: Twenty stroke subjects (time since stroke 5–127months) completed the study. Subjects were assessed with and without ankle-foot orthosis. Functional balance was assessed using the Berg Balance Scale, Timed Up & Go test, Timed Balance Test, 10-m walking test and Functional Ambulation Categories. Weight-bearing asymmetry and dynamic balance control were assessed with force plates on a movable platform.Findings: No significant effects of ankle-foot orthoses were found for weight-bearing asymmetry and dynamic balance control, but significant differences in favour of ankle-foot orthosis use were... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817342 Sun, 09 Aug 2009 23:00:00 +0100 2817342 http://www.medworm.com/index.php?rid=2817338&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001582%2Fabstract%3Frss%3Dyes In this study, a two-way mixed design ANOVA was applied to investigate the effects of the gastrocnemius tightness on the joint angle and joint work during walking.Methods: Twenty-two patients with muscular tightness of gastrocnemius muscle (15° of ankle dorsiflexion with knee extended) participated in this study. The joint angle and work at hip, knee, and ankle joints during the stance phase were analyzed at two preset cadences of 100steps/min and 140steps/min.Findings: Significantly greater flexion angles at hip (P=0.025) and knee (P=0.001) were found in the tightness group at the time of maximal ankle dorsiflexion. Significantly less work generation at knee (P=0.034) and greater work absorption at ankle (P=0.024) were detected in the tightness group.Interpretation: The subjects with gas... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817338 Sun, 09 Aug 2009 23:00:00 +0100 2817338 http://www.medworm.com/index.php?rid=2817337&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001594%2Fabstract%3Frss%3Dyes This study investigated whether or not the patterns and quantitative characteristics of the trunk and lower extremity muscle activations associated with stepping, which represents an important movement for arresting falls, differ between middle-aged adults and young adults.Methods: Nine healthy young adults (age=22[3] years) and nine healthy middle-aged adults (age=52[8] years), performed a single-step, volitional, fast forward stepping movement with each leg. The stepping movement was divided into the step-initiation, single-leg-support, and landing phases based on foot-switch signals. The activation sequence, occurrence rate, onset latency, burst duration, and normalized co-contraction duration of the tibialis anterior, medial gastrocnemius, rectus femoris, biceps femoris, and gluteus me... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817337 Sun, 09 Aug 2009 23:00:00 +0100 2817337 http://www.medworm.com/index.php?rid=2817332&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001600%2Fabstract%3Frss%3Dyes The objective of this study was to investigate the relation between the active head restraint position and peak neck motion using a new human model of the neck.Methods: The model consisted of an osteoligamentous neck specimen mounted to the torso of a rear impact dummy and carrying an anthropometric head stabilized with muscle force replication. Rear impacts (7.1 and 11.1g) were simulated with and without the active head restraint. Physiologic rotation was determined from intact flexibility tests. Significant reductions (P0.3 and P (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817332 Sun, 09 Aug 2009 23:00:00 +0100 2817332 http://www.medworm.com/index.php?rid=2817336&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001636%2Fabstract%3Frss%3Dyes We examined this issue by examining the kinematic, kinetic and metabolic demands associated with overground and treadmill walking at matched speeds and also explored the effect of increasing treadmill speed.Methods: Ten people with hemiparesis walked overground at their preferred speed which was matched on the treadmill. Belt speed was then increased 10% and 20% above preferred speed. Temporal-distance outcomes, angular kinematics and vertical ground reaction forces were recorded during steady state (stable heart rate and oxygen uptake).Findings: Step and stance times were longer when walking overground but the degree of symmetry was comparable for both surfaces. In contrast kinematic data revealed significant interlimb asymmetry with respect to all lower limb joint excursions during overg... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817336 Thu, 06 Aug 2009 23:00:00 +0100 2817336 http://www.medworm.com/index.php?rid=2817340&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001648%2Fabstract%3Frss%3Dyes Abstract: Background: Despite partial meniscectomies and ligament reconstructions as treatments of choice for meniscal and ligament injuries, respectively, the knee joint osteoarthritis persists.Methods: A detailed nonlinear finite element model of the knee joint was developed to evaluate biomechanics of the tibiofemoral joint under 200N drawer load with and without 1500N compression preload. The model incorporated composite structure of cartilage and meniscus. The effects on joint response and articular contact pressure of unilateral partial meniscectomy, of changes in prestrain or material properties of the anterior cruciate ligament and of their combination were investigated.Findings: Compressive preload further increases anterior cruciate ligament strains/forces in drawer loading. Part... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817340 Tue, 04 Aug 2009 23:00:00 +0100 2817340 http://www.medworm.com/index.php?rid=2817333&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001041%2Fabstract%3Frss%3Dyes Abstract: Background: Deviated wrist postures have been linked to carpal tunnel syndrome development, yet the effect of posture on carpal tunnel volume remains unclear. The purposes of this study were (i) to evaluate the effect of boundary definitions on tunnel volume estimates in neutral and non-neutral (30° flexion, 30° extension) wrist postures and (ii) to develop a biomechanical wrist simulation to predict posture-related changes in tunnel volume.Methods: Two carpal tunnel volume measures were calculated using (i) ulnar bony landmarks and (ii) radial and ulnar bony landmarks identified directly from magnetic resonance imaging (MRI) scans. A third volume measure combined computerized tunnel reconstructions with modelled bone surfaces to calculate an anatomically landmarked volume. Six... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2817333 Tue, 04 Aug 2009 23:00:00 +0100 2817333 http://www.medworm.com/index.php?rid=2722216&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001545%2Fabstract%3Frss%3Dyes Abstract: Background: To minimise wear of the meniscal component in total ankle replacement, a three-component artificial joint has recently been developed. This new prosthesis has convex spherical tibial and anticlastic talar metal components with non-anatomic but ligament-compatible shapes in the sagittal plane, and a fully conforming ultra-high-molecular-weight-polyethylene meniscal component inserted in between. The in vitro wear of meniscal components can be assessed using a four-station joint simulator. The study was aimed at comparing wear patterns obtained in vitro with those observed in implant retrievals with the same design.Methods: The wear tests were run in a joint wear simulator at a frequency of 1.1Hz for two million cycles. Three bearings within corresponding metal componen... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722216 Wed, 29 Jul 2009 23:00:00 +0100 2722216 http://www.medworm.com/index.php?rid=2722211&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001508%2Fabstract%3Frss%3Dyes Abstract: Background: Falling onto the outstretched hand is a major cause of upper extremity injury. The overall objectives of this study were to develop an experimental model for elbow load during a simulated fall onto one-armed arrest using three different forearm axially rotated postures as alternative fall arrest strategies. Additionally, the relationship between the elbow flexion angle and different axially rotated postures were also investigated.Methods: Fifteen healthy young male Taiwanese graduate students with an average age of 23years were studied. Subjects performed a one-armed arrest of a 5cm fall onto a force plate. Each subject fell onto the force plate with his forearm 45° axial externally rotated (ER), non-rotated (NR), and 45° axial internally rotated (IR) postures. Kine... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722211 Wed, 29 Jul 2009 23:00:00 +0100 2722211 http://www.medworm.com/index.php?rid=2722215&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001557%2Fabstract%3Frss%3Dyes Abstract: Background: Clinical results of total ankle arthroplasty with early designs were disappointing. Recently-developed ankle prostheses have good mid-term results; however, limited information is available regarding effects of total ankle arthroplasty on ankle laxity.Methods: Eight cadaveric lower extremities were tested with a custom device which enabled measurement of multi-axial forces, moments, and displacement during applied axial, shear, and rotational loading. Tests consisted of anterior–posterior and medial–lateral translation and internal–external rotation of the talus relative to the tibia during axial loads on the tibia simulating body weight (700N) and an unloaded condition (5N). Tests were performed in neutral, dorsiflexion, and plantarflexion. Laxity was determine... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722215 Sun, 26 Jul 2009 23:00:00 +0100 2722215 http://www.medworm.com/index.php?rid=2722213&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001569%2Fabstract%3Frss%3Dyes Abstract: Background: To stabilize the femoral head in ipsilateral femoral neck and shaft fractures, one cannulated screw was supplemented in front of the reconstruction interlocking nail (recon nail).Methods: Twenty-eight left sawbone femurs were divided into two groups. The 14 femurs in each group were osteotomized with subcapital or transcervical fractures. The shafts of all femurs were also osteotomized, and 1cm of the distal segmental cortex was excised. Next, all the fractures were treated with static recon nails to concomitantly stabilize both femoral neck and shaft fractures. Additionally, seven subcapital fractures and seven transcervical fractures were supplemented with one cannulated screw in front of the recon nails. All specimens were tested with a Material Testing System mach... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722213 Sun, 26 Jul 2009 23:00:00 +0100 2722213 http://www.medworm.com/index.php?rid=2722212&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900151X%2Fabstract%3Frss%3Dyes This study investigates the mechanical strength of single polyaxial interfaces of different volar radius plates.Methods: Single screw–plate interfaces of the implants Palmar 2.7 (Königsee Implantate und Instrumente zur Osteosynthese GmbH, Allendorf, Germany), VariAx™ (Stryker Leibinger GmbH & Co. KG, Freiburg, Germany) und Viper™ (Integra LifeSciences Corporation, Plainsboro, NJ, USA) were tested by cantilever bending. The strength of 0°, 10° and 20° screw locking angle was obtained during static and dynamic loading.Findings: The Palmar 2.7 interfaces showed greater ultimate strength and fatigue strength than the interfaces of the other implants. The strength of the VariAx™ interfaces was about 60% of Palmar 2.7 in both, static and dynamic loading. No dynamic testing was applie... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722212 Sun, 26 Jul 2009 23:00:00 +0100 2722212 http://www.medworm.com/index.php?rid=2722207&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001521%2Fabstract%3Frss%3Dyes This study demonstrates that an isometric load was possibly applied and a significant intensity of electrical stimulation could be tolerated and delivered to the isometrically loaded facial muscle. The isometric loading would be utilized for loaded facial neuromuscular electrical stimulation therapeutically and also for measurement of the force generation capacity of the zygomaticus major diagnostically. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722207 Thu, 23 Jul 2009 23:00:00 +0100 2722207 http://www.medworm.com/index.php?rid=2722222&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001363%2Fabstract%3Frss%3Dyes The authors of the above article regret that a reference (Baca et al., 2008) was incomplete in this paper. The complete reference can be found below. Baca, V., Horak, Z., Mikulenka, P., Dzupa, V., 2008. Comparison of an inhomogeneous orthotropic and isotropic material models used for FE analyses. Med. Eng. Phys. 30, 924–930. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722222 Mon, 20 Jul 2009 23:00:00 +0100 2722222 http://www.medworm.com/index.php?rid=2722219&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001533%2Fabstract%3Frss%3Dyes Abstract: Background: The study attempted to highlight the differences of mechanical properties in microchambers and macrochambers between patients with type 2 diabetes mellitus and age-matched healthy volunteers.Methods: A total of 29 heels in 18 diabetic patients and 28 heels in 16 age-matched healthy participants were examined by a loading device consisting of a 10-MHz compact linear-array ultrasound transducer, a Plexiglas cylinder, and a load cell. Subjects in both groups were on average about 55years old with a body mass index of approximately 25kg/m2. A stepping motor was used to progressively load the transducer on the tested heels at a velocity of 6mm/s from zero to the maximum stress of 78kPa. Unloaded thickness, strain, and elastic modulus in microchambers, macrochambers and hee... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722219 Mon, 20 Jul 2009 23:00:00 +0100 2722219 http://www.medworm.com/index.php?rid=2574880&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001387%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2574880 Tue, 07 Jul 2009 11:20:13 +0100 2574880 http://www.medworm.com/index.php?rid=2722218&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001338%2Fabstract%3Frss%3Dyes Abstract: Background: The human foot has to bear loads during all kinds of bipedal locomotion throughout the whole life. Rapid developmental changes of foot morphology and foot function occur during the first years of walking. Furthermore, disease dependent modifications can also have an influence on plantar loading. Therefore, it is reasonable to assume that foot function will undergo changes in life. However, the main differences between the pressure patterns in young and elderly have not been well described. The aim of the study was to evaluate age-dependent pressure patterns in different age-related stages.Methods: Hundred and four healthy humans of four different age groups were retrospectively analysed by means of plantar pressure measurements (toddlers: mean age 1.0 (SD 0.2) year; 7... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722218 Sun, 28 Jun 2009 23:00:00 +0100 2722218 http://www.medworm.com/index.php?rid=2722214&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001326%2Fabstract%3Frss%3Dyes Abstract: Background: Increased contact stress with a femoral resurfacing prosthesis implanted in the medial femoral condyle and a non-functional meniscus is of concern for potential deleterious effects on tibiofemoral contact mechanics.Methods: Peak contact pressures were determined in seven fresh frozen human cadaveric specimens using a pressure sensitive sensor placed in the medial compartment above the menisci. A knee simulator was used to test each knee in static stance positions (5°/15°/30°/45°) and through 10 dynamic knee flexion cycles (5–45°) with single body weight ground reaction force which was adjusted to the living body weight of the cadaver donor. All specimens were tested in three different conditions: untreated knee (A); flush implantation of a 20mm resurfacing pros... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722214 Sun, 28 Jun 2009 23:00:00 +0100 2722214 http://www.medworm.com/index.php?rid=2722206&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900134X%2Fabstract%3Frss%3Dyes The objective of this study was to examine differences in postural stability and the speed of response between young adults, low fall-risk older adults, and high fall-risk older adults during voluntary postural sway movements.Methods: Twenty-five young adults (25±4years), and 32 low fall-risk (74±5years), and 16 high fall-risk (79±7years) older adults performed voluntary sway and rapid orthogonal transitions of voluntary sway between the anterior–posterior and medial–lateral directions. Measures included reaction and movement time and the amplitudes of the centre of pressure, centre of mass, and the separation distance between the centre of pressure and centre of mass.Findings: Both fall-risk groups compared to the young had slower reaction and movement time, greater centre of press... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722206 Sun, 28 Jun 2009 23:00:00 +0100 2722206 http://www.medworm.com/index.php?rid=2574890&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001351%2Fabstract%3Frss%3Dyes The following letter from Sacco et al. is in response to the letter from . Unfortunately, due to communication problems among the authors, it did not arrive before the deadline for reply but is published here for the benefit of readers who are interested in this discussion. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2574890 Sun, 28 Jun 2009 23:00:00 +0100 2574890 http://www.medworm.com/index.php?rid=2722217&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001089%2Fabstract%3Frss%3Dyes Abstract: Background: Multiple factors may contribute to hammer toe deformity at the metatarsophalangeal joint. The purposes of this study were to (1) compare the ratio of toe extensor/flexor muscle strength in toes 2–4 among groups with and without hammer toe deformity, (2) to determine correlations between the ratio of toe extensor/flexor muscle strength in toes 2–4, and metatarsophalangeal joint deformity (3) to determine if other clinical measures differ between groups and if these measures are correlated with metatarsophalangeal joint angle.Methods: Twenty-seven feet with visible hammer toe deformity and 31 age matched feet without hammer toe deformity were tested. Toe muscle strength was measured using a dynamometer and the ratio of toe extensor muscle strength to flexor muscle s... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722217 Tue, 16 Jun 2009 23:00:00 +0100 2722217 http://www.medworm.com/index.php?rid=2722209&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001077%2Fabstract%3Frss%3Dyes Abstract: Background: The aim of this laboratory study was to investigate the effects of eccentric exercises on the trapezius muscle spatial electromyographic (EMG) activity during computer work with active and passive pauses.Methods: Twelve healthy male subjects performed computer work with passive (relax) and active (30% maximum voluntary contraction of shoulder elevation) pauses given every 40s over 2 days, before, immediately and 24h after eccentric exercise. Surface EMG signals were recorded from four parts of the trapezius during computer work.Findings: EMG amplitude during computer work decreased immediately after exercise (P (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722209 Tue, 16 Jun 2009 23:00:00 +0100 2722209 http://www.medworm.com/index.php?rid=2722221&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001065%2Fabstract%3Frss%3Dyes Abstract: Background: Standing balance is impaired in individuals with knee osteoarthritis and is associated with disease severity. The effects of surgical interventions on standing balance have received little attention. The purpose of the present study was to examine measures of balance during tests of single-limb standing before and after medial opening wedge high tibial osteotomy – a lower limb re-alignment procedure for those with varus alignment and knee osteoarthritis.Methods: Standing balance was assessed in 49 individuals prior to and 12 months following medial opening wedge high tibial osteotomy. Participants performed three trials of single-limb balance lasting 10s each while standing on a force platform. Anteroposterior and mediolateral coordinates of the centre of pressure w... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722221 Sun, 14 Jun 2009 23:00:00 +0100 2722221 http://www.medworm.com/index.php?rid=2466323&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001272%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2466323 Tue, 09 Jun 2009 20:46:42 +0100 2466323 http://www.medworm.com/index.php?rid=2466322&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001120%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2466322 Tue, 09 Jun 2009 20:46:40 +0100 2466322 http://www.medworm.com/index.php?rid=2722210&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900103X%2Fabstract%3Frss%3Dyes Abstract: Background: Glenohumeral arthroplasty has produced results far inferior to those seen with hip and knee joint procedures. Therefore, the objective of this study was to evaluate the biomechanical parameters of the glenohumeral joint before and after total shoulder arthroplasty and bipolar hemiarthroplasty in 12 different positions simulating overhead activities.Methods: Six matched pairs of cadaveric shoulders were used with a custom shoulder testing system to quantify the joint reactive force, contact areas, contact patterns and contact pressures in 12 different positions simulating overhead activities. The entire study was performed for the anatomic glenohumeral joint and following total shoulder arthroplasty on one side, and for the anatomic glenohumeral joint and following bip... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722210 Sun, 07 Jun 2009 23:00:00 +0100 2722210 http://www.medworm.com/index.php?rid=2574887&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001016%2Fabstract%3Frss%3Dyes Abstract: Background: Valgus bending of the knee is promoted as an anterior cruciate ligament injury mechanism and is associated with a characteristic “footprint” of bone bruising. The hypothesis of this study was that during ligamentous failure caused by valgus bending of the knee, high tibiofemoral contact pressures induce acute osteochondral microdamage.Methods: Four knee pairs were loaded in valgus bending until gross injury with or without a tibiofemoral compression pre-load. The peak valgus moment and resultant motions of the knee joint were recorded. Pressure sensitive film documented the magnitude and location of tibiofemoral contact. Cartilage fissures were documented on the tibial plateau, and microcracks in subchondral bone were documented from micro-computed tomography scan... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2574887 Sun, 07 Jun 2009 23:00:00 +0100 2574887 http://www.medworm.com/index.php?rid=2722220&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001028%2Fabstract%3Frss%3Dyes Abstract: Background: The purpose of this study was to investigate the ankle range of motion during neuropathic gait and its influence on plantar pressure distribution in two phases during stance: at heel–strike and at push-off.Methods: Thirty-one adults participated in this study (control group, n=16; diabetic neuropathic group, n=15). Dynamic ankle range of motion (electrogoniometer) and plantar pressures (PEDAR-X system) were acquired synchronously during walking. Plantar pressures were evaluated at rearfoot, midfoot and forefoot during the two phases of stance. General linear model repeated measures analysis of variance was applied to investigate relationships between groups, areas and stance phases.Findings: Diabetic neuropathy patients walked using a smaller ankle range of motion i... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722220 Wed, 03 Jun 2009 23:00:00 +0100 2722220 http://www.medworm.com/index.php?rid=2574885&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000977%2Fabstract%3Frss%3Dyes Abstract: Background: Upright sitting is one of the first developmental motor milestones achieved by infants, and sitting postural sway provides a window into the developing motor control system. A variety of posture sway measures can be used, but the optimal measures for infant development have not been identified.Methods: We have collected sitting postural sway data from two groups of infants, one with typical development (n=33), and one with delayed development and either diagnosed with or at risk for cerebral palsy (n=26), when the infants had developed to the point where they could just maintain sitting for about 10s. Postural sway data was collected while infants were sitting on a force platform, and the center of pressure was analyzed using both linear and nonlinear measures.Finding... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2574885 Tue, 02 Jun 2009 23:00:00 +0100 2574885 http://www.medworm.com/index.php?rid=2574881&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001004%2Fabstract%3Frss%3Dyes Abstract: Background: Comparative studies between single-joint electromyography (EMG)- and optimization-driven models of the human spine in estimating trunk muscle and spinal compression forces have not been conclusive. Due to associated implications in ergonomic applications as well as prevention and treatment managements of low-back disorders, there is a need to critically compare existing single- and multi-joint spine models.Methods: A comprehensive comparison of muscle forces and spinal loads estimated by a single-joint (L5–S1 or L4–L5) EMG-driven model (EMGAO) and a multi-joint (T1–S1) Kinematics-driven finite element model (KD) of the spine under different static lifting activities in upright standing posture is carried out. Identical geometry for the spine and trunk musculatur... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2574881 Tue, 02 Jun 2009 23:00:00 +0100 2574881 http://www.medworm.com/index.php?rid=2722208&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309001053%2Fabstract%3Frss%3Dyes Abstract: Background: Pedicle screw fixation in a severely osteoporotic spine remains a challenge for orthopedic surgeons. The previous literature does not adequately address the effects of radial holes for cannulated screws with cement injection and pilot hole tapping on the bone/screw interfacial strength.Methods: Specially designed cannulated pedicle screws, with or without radial holes, were installed in tapped and untapped pilot holes and then injected with cement. A uniform synthetic bone (test block) was used to provide a platform for each screw design. Specimens with inserted screws were then tested for axial pullout failure.Findings: (1) Cannulated screws with cement augmentation significantly increased the pullout strength in comparison to solid screws. Additionally, the amount o... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2722208 Sun, 31 May 2009 23:00:00 +0100 2722208 http://www.medworm.com/index.php?rid=2574882&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000989%2Fabstract%3Frss%3Dyes Abstract: Background: A number of different models for human trunk kinematics during locomotion have been proposed, though mainly addressing specific clinical questions rather than general populations. These differ considerably for the skeletal segments considered, marker-set, anatomical axis and frame definitions, and joint conventions. The scope of the present study is to compare quantitatively these models on the basis of the same motion.Methods: Ten subjects were analysed, instrumented with a single comprehensive marker-set of 14 markers identified from the union of the corresponding from eight current models for trunk kinematics. Activities of daily living (walking, chair rising/sitting, step-up/down), elementary trunk movements (flexion, bending and axial rotation), and isolated moti... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2574882 Sun, 31 May 2009 23:00:00 +0100 2574882 http://www.medworm.com/index.php?rid=2574886&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000953%2Fabstract%3Frss%3Dyes Abstract: Background: The histologic and biomechanical effects of intra-articular hyaluronic acid on the anterior cruciate ligaments of rats were investigated.Methods: Thirty rats were divided into three groups, i.e., the hyaluronic acid group, saline group, and control group. The hyaluronic acid and saline groups received a total of four intra-articular injections, whereas no injection was administered to the control group. The hyaluronic acid group was injected with 50μg (0.05cc) hyaluronic acid, and the saline group was injected with 50μl (0.05cc) of 0.9% sodium chloride solution. All of the rats were sacrificed on day 29 and the femur-anterior cruciate ligament–tibia complexes from the right knees were prepared, tested mechanically, and evaluated histologically.Findings: The mode o... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2574886 Sun, 24 May 2009 23:00:00 +0100 2574886 http://www.medworm.com/index.php?rid=2493635&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000990%2Fabstract%3Frss%3Dyes With great interest we read the recent paper by . They investigated muscle activation patterns and ground reaction force in people with diabetic polyneuropathy with (UDG) and without (diabetic neuropathic group (DG)) a history of plantar ulceration and in healthy controls (control group (CG)). The most interesting implication of their study is that increased plantar pressures under the forefoot are related to dysfunction of muscles in the leg, i.c. m.vastus lateralis (VL) and m. gastrocnemius lateralis (LG). This idea was initially conceived by , but has received little attention in later studies. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493635 Sun, 24 May 2009 23:00:00 +0100 2493635 http://www.medworm.com/index.php?rid=2574889&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900093X%2Fabstract%3Frss%3Dyes Abstract: Background: Techniques such as varying screw insertion angles and the use of locked plating have been shown to improve the strength of fixation in bone. The effects of these methods is less clearly understood in bone of exceedingly poor quality.Methods: Forty plate-bone constructs were assembled and divided into four groups of ten. Perpendicularly placed screws were placed in one group, convergently placed crossing screws were placed in a second group, an oblique end screw was placed in a third group, and a fourth group utilized perpendicularly placed locking screws in a locking plate. All test subjects were mounted and loaded in cantilever bending to the point of failure. Stiffness, initial load to failure, and maximal load tolerated were all analyzed.Findings: All four groups d... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2574889 Thu, 21 May 2009 23:00:00 +0100 2574889 http://www.medworm.com/index.php?rid=2493638&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900076X%2Fabstract%3Frss%3Dyes Acknowledgement of the funding source was inadvertently omitted from the published version of the above manuscript. Funding for this study was provided by NIH P20-RR16458. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493638 Thu, 21 May 2009 23:00:00 +0100 2493638 http://www.medworm.com/index.php?rid=2493639&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000758%2Fabstract%3Frss%3Dyes Acknowledgement of the funding source was inadvertently omitted from the published version of the above manuscript. Funding for this study was provided by NIH P20-RR16458. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493639 Wed, 20 May 2009 23:00:00 +0100 2493639 http://www.medworm.com/index.php?rid=2574883&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000941%2Fabstract%3Frss%3Dyes Abstract: Background: Ambulatory people with central cord syndrome often require assistive devices. The selection of a suitable assistive device should be based on an objective assessment. Our objective in this study was to determine whether there was any difference in using two crutches over one crutch, considering that these patients have bilateral upper-limb involvement.Methods: Kinematic gait analysis was conducted in 12 patients with central cord syndrome of more than one year of evolution and functional capacity for walking with one crutch or without crutches. Patients were asked to walk with one crutch and with two crutches at a freely chosen walking speed through a 10-m walkway. Three-dimensional kinematic equipment based on active markers was used to analyze temporospatial and art... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2574883 Tue, 19 May 2009 23:00:00 +0100 2574883 http://www.medworm.com/index.php?rid=2574888&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000928%2Fabstract%3Frss%3Dyes Abstract: Background: Compared to conventional ultra-high molecular weight polyethylene (UHMWPE), crosslinked polyethylene showed significantly reduced wear rate in hip simulation and early prospective-randomized clinical studies. The crosslinking process can reduce the mechanical properties of UHMWPE, particularly the fatigue strength. UHMWPE fatigue occurs more frequently in the knee joint than in the hip joint due to its higher contact stresses and there is therefore an increased concern of mechanical failure. Therefore, the purpose of this study was to determine the wear behaviour and the wear rates of different current knee designs and bearing materials.Methods: In a knee-joint-simulator four kinds of crosslinked polyethylene (one produced by sequential irradiation and annealing proce... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2574888 Sun, 17 May 2009 23:00:00 +0100 2574888 http://www.medworm.com/index.php?rid=2574884&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000916%2Fabstract%3Frss%3Dyes The objective of the present study was to compare the benefits of the wheelchair seat cushions most frequently used in a population of patients with spinal cord injury in terms of pressure distribution and contact surface at the user-cushion interface.Methods: Each one of 48 patients with spinal cord injury was seated in his or her own wheelchair on the four models of cushions analyzed (low-profile air, high-profile air, dual-compartment air, and gel and firm foam), which were presented in randomized order. The pressure distribution readings and support surface area of the user-cushion interface were obtained with a matrix of piezocapacitive sensors.Findings: The dual-compartment air cushion yielded lower readings for all pressure parameters analyzed (Pmax, Pmean, Psd, and Pisch) than the ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2574884 Sun, 17 May 2009 23:00:00 +0100 2574884 http://www.medworm.com/index.php?rid=2493636&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000965%2Fabstract%3Frss%3Dyes The publisher regrets that the above listed Award Paper was published without the correct heading. The paper should have been listed as follows: ASB Clinical Biomechanics Award 2008 (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493636 Wed, 13 May 2009 23:00:00 +0100 2493636 http://www.medworm.com/index.php?rid=2493637&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000795%2Fabstract%3Frss%3Dyes The authors would like to point out that there was an error in the heading of . The correct table and heading can be found below: (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493637 Tue, 12 May 2009 23:00:00 +0100 2493637 http://www.medworm.com/index.php?rid=2493629&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000783%2Fabstract%3Frss%3Dyes Background: Both ageing and speed definitely affect gait patterns. Since most of the comparisons between young and elderly people while walking have been carried out at different “self-selected” speeds, results might be biased by a lack of control of the effects of both the concomitant issues. Therefore, further investigations aimed at separating the influence of both the sources of variability are required.Methods: Nine young and eight elderly healthy subjects walked on a treadmill at five normalised speeds according to the Froude Number, from 0.5 to 1.3m/s. Step parameters and peaks belonging to kinematic and kinetic patterns have been compared between the groups and over the five speeds by the two-factor (Group and Speed) ANOVA.Findings: After making walking speed comparable between... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493629 Mon, 11 May 2009 23:00:00 +0100 2493629 http://www.medworm.com/index.php?rid=2493625&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000771%2Fabstract%3Frss%3Dyes Abstract: Background: Interspinous process implants, used to augment lumbar spine surgery, putatively induce a local segmental lumbar kyphosis yet few investigations outline the effect in vivo on thoracolumbar sagittal curvature. Changes in lumbar skeletal alignment and posture have traditionally relied upon radiographic and back surface spinal curvature measurements, respectively.Methods: Lumbar lordosis curvature in 10 healthy subjects (6F, 4M; mean age 36 years) and 10 interspinous implant lumbar surgery patients (5F, 5M; mean age 51 years) was assessed with rasterstereography at baseline and at 6 weeks. Skeletal lumbar lordosis in standing was measured from lateral erect radiography pre- and 6 weeks post-operatively in the surgical cohort, and compared to angulation obtained for surfac... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493625 Wed, 29 Apr 2009 23:00:00 +0100 2493625 http://www.medworm.com/index.php?rid=2371881&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000539%2Fabstract%3Frss%3Dyes We corrected the values of initial stiffness, initial damage rate and secondary damage rate in . Since the significance of comparison was not affected by the correction, our conclusion maintained. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2371881 Wed, 29 Apr 2009 03:43:42 +0100 2371881 http://www.medworm.com/index.php?rid=2371880&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000448%2Fabstract%3Frss%3Dyes Abstract: Background: The purpose of this study was to determine the plantar forefoot offloading efficacy of a new prefabricated vacuum-cushioned cast replacement system designed for foot ulcer treatment in neuropathic diabetic patients.Methods: Fifteen diabetic subjects with peripheral neuropathy underwent in-shoe plantar pressure assessment while walking in five different footwear types: a standard vacuum-cushioned system with instantly moldable vacuum cushion and roller outsole, two modified vacuum-cushioned systems, one with flat surface vacuum cushion and one with flat outsole, a forefoot offloading shoe, and a control shoe. Regional peak pressures, pressure–time integrals, and inter-regional load transfers were calculated to determine the mechanical action of the footwear. Perceive... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2371880 Wed, 29 Apr 2009 03:43:39 +0100 2371880 http://www.medworm.com/index.php?rid=2371879&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000540%2Fabstract%3Frss%3Dyes This study revealed that seven separate variables from the static balance (anterior/posterior and medial/lateral displacement and velocity) and motoneuron pool excitability constructs (single-legged recurrent inhibition and single- and double-legged paired reflex depression) accurately classified over 86% of participants with unstable ankles.Interpretation: These results suggest that a multivariate approach may be necessary to understand the role of sensorimotor function in chronic ankle instability, and to the development of appropriate rehabilitation and prevention programs. Out of the four overall constructs, only two were needed to accurately classify the participants into two groups. This indicates that static balance and motoneuron pool excitability may be more clinically important i... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2371879 Wed, 29 Apr 2009 03:43:29 +0100 2371879 http://www.medworm.com/index.php?rid=2371878&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000552%2Fabstract%3Frss%3Dyes Abstract: Background: The post/cam mechanism of posterior cruciate substituting total knee arthroplasty, which is intended to achieve maximum range of flexion, offers the risk of failure due to mechanical overload. The purpose of this in vitro study was to investigate load and contact pressure on the inlay post of posterior substituting knee prosthesis with different designs.Methods: Isokinetic extension/flexion motions of seven fresh frozen left knee specimens were simulated dynamically in a specially designed knee simulator with an extension moment of 31Nm. After implantation of the knee prosthesis system, which provides a fixed and a rotating posterior cruciate substituting inlay, a pressure sensitive film was fixed on the inlay post surface to measure maximum load and contact pressure.... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2371878 Wed, 29 Apr 2009 03:43:21 +0100 2371878 http://www.medworm.com/index.php?rid=2371877&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000503%2Fabstract%3Frss%3Dyes This study shows the importance of re-evaluating knee kinematics over time. The axial rotation of both the femoral component as the insert decreased over time, indicating a kinematic change caused by intrinsic factors. The decline in rotation of the insert could be explained by increased impingement and the formation of fibrous tissue. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2371877 Wed, 29 Apr 2009 03:43:16 +0100 2371877 http://www.medworm.com/index.php?rid=2371876&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000436%2Fabstract%3Frss%3Dyes Abstract: Background: Initial fixation strength is critical for the early post-operative rehabilitation of patients with anterior cruciate ligament reconstructions. However, even the best femoral fixation devices remain controversial. We compared the biomechanical characteristics of tendon grafts fixed by different biodegradable femoral fixation devices following anterior cruciate ligament reconstruction.Methods: The Bio-TransFix, Rigidfix, Bioscrew with EndoPearl augmentation and Bioscrew devices were used to fix porcine flexor digitorum profundus tendon grafts in 32 porcine femora. Displacement of each tendon graft was evaluated after cyclic loading testing. Stiffness, ultimate failure load and failure mode of these fixation devices were measured with load-to-failure testing.Findings: Th... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2371876 Wed, 29 Apr 2009 03:43:14 +0100 2371876 http://www.medworm.com/index.php?rid=2371875&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000497%2Fabstract%3Frss%3Dyes In this study, the in vitro primary stability of the thrust plate prosthesis was compared to two types of short-stemmed prostheses. In addition to the well-established Mayo prosthesis, the modular Metha prosthesis was tested using cone adapters with 130° and 140° neck-shaft-angles.Methods: The prostheses were implanted in composite femurs and loaded dynamically (300–1700N). Three-dimensional micromotions at the bone-prosthesis interface were measured. In addition, the three-dimensional deformations at the surface of the composite femur were measured to gain data on the strain distribution.Findings: For all tested prostheses, the micromotions did not exceed 150μm, the critical value for osteointegration. The thrust plate prosthesis revealed similar motions as the short-stemmed prosthes... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2371875 Wed, 29 Apr 2009 03:43:13 +0100 2371875 http://www.medworm.com/index.php?rid=2371874&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000485%2Fabstract%3Frss%3Dyes Abstract: Background: The calf muscles of children with cerebral palsy are often spastic, which can lead to an equinus gait pattern. Although spasticity is defined as a velocity-dependent increase in muscle tone, very little is known about the effect of walking speed on muscle–tendon behavior of spastic muscles during gait. The aim of this study was to investigate gastrocnemius and soleus length and lengthening velocity during gait in spastic muscles with and without static contractures compared to non-spastic muscles, as well as the effect of walking speed, and the interacting effect of walking speed and spasticity on muscle–tendon length and lengthening velocity.Methods: Seventeen ambulatory children with spastic cerebral palsy and 11 typically developing children, aged 6–12, walke... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2371874 Wed, 29 Apr 2009 03:43:10 +0100 2371874 http://www.medworm.com/index.php?rid=2371873&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000527%2Fabstract%3Frss%3Dyes This study investigated the effect of Tai Chi Chuan exercise performed at different speed on leg muscle activity characteristics in both young and old Tai Chi Chuan practitioners.Methods: Surface electromyography of six leg muscles and kinematics of lower extremity joints were measured in young and old subjects during Tai Chi Chuan practice at fast, normal, and slow speed, respectively. The magnitude and duration of activation, and durations of isometric, concentric and eccentric actions of each muscle were compared among three speeds and between two groups.Findings: The activation duration of all six leg muscles was significantly longer at slower speed than at faster speed (P (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2371873 Wed, 29 Apr 2009 03:43:10 +0100 2371873 http://www.medworm.com/index.php?rid=2371872&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900045X%2Fabstract%3Frss%3Dyes Abstract: Background: Increased muscle co-activation during gait has been identified as a neuromuscular alteration associated with knee osteoarthritis, however levels of co-activation among different osteoarthritis severity have not been established. The purpose of this study was to determine if differences in co-activation could be detected among asymptomatic controls, those with moderate and those with severe osteoarthritis using a co-activation index and a pattern recognition technique.Methods: Surface electromyograms from vastus lateralis and medialis, lateral and medial hamstring and gastrocnemius pairs were recorded from 63 asymptomatic, 59 moderate and 48 severe osteoarthritic subjects during self-selected walking. A co-activation index was calculated over the initial stance for fou... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2371872 Wed, 29 Apr 2009 03:43:09 +0100 2371872 http://www.medworm.com/index.php?rid=2371871&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000813%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2371871 Wed, 29 Apr 2009 03:43:09 +0100 2371871 http://www.medworm.com/index.php?rid=2493631&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000746%2Fabstract%3Frss%3Dyes Abstract: Background: Tendon tissue contains oestrogen receptors and is therefore likely to be responsive to female sex hormones. Here we examine any effect of levels of female sex hormones associated with the menstrual cycle phase on corresponding tendon mechanical properties.Methods: Fifteen healthy females aged 23 (SEM 1.0years) underwent three assessments of medial gastrocnemius tendon mechanical properties. Assessments were carried out once during days 1–4, 12–14 and 20–23 (with day 1 being the first day of menstruation). Venous blood samples were taken on the same days as tendon properties assessments to quantify serum levels of oestradiol and progesterone.Findings: There was no significant difference in the stiffness of the medial gastrocnemius tendon over the course of the me... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493631 Thu, 23 Apr 2009 23:00:00 +0100 2493631 http://www.medworm.com/index.php?rid=2493632&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000734%2Fabstract%3Frss%3Dyes The objective of this study was to characterize biomechanics of gait in a group of subjects with disarticulation through the talonavicular (T-N) and calcaneocuboid (C-C) (midtarsal) joints wearing two different prosthetic solutions: silicone prostheses and conventional prostheses.Methods: Four subjects that underwent Chopart partial foot amputation were included in the study. Silicone prosthesis was custom manufactured for each individual subject. Instrumented gait analysis was performed in each subject in four experimental conditions: barefooted, barefooted and wearing silicon prosthesis, wearing footwear with conventional prosthesis and wearing footwear with silicon prosthesis. Comparisons and statistical analysis were made between both barefooted conditions and both foot-wearing conditi... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493632 Tue, 21 Apr 2009 23:00:00 +0100 2493632 http://www.medworm.com/index.php?rid=2344464&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900028X%2Fabstract%3Frss%3Dyes Abstract: Background: Suture knots used in tendon surgery must be strong but small enough so that they do not hinder gliding. For this purpose, we devised a unique “antislip” knot.Methods: Three suture materials were used: Ethibond, Fiberwire, and Nespron. They were tied with either the antislip knot using a pair of United States Pharmacopeia (USP) 2 sutures or with a conventional reef knot using USP2 single sutures. The volume and tensile strength of the knots were measured (n=25 for each combination of suture and method).Findings: The maximum tensile strength was observed with Fiberwire antislip knots with five throws (mean 587N) and six throws (mean 590N), and Nespron antislip knots with five throws (mean 554N) and six throws (mean 552N); no significant differences were found among ... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344464 Mon, 20 Apr 2009 17:57:48 +0100 2344464 http://www.medworm.com/index.php?rid=2344463&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000187%2Fabstract%3Frss%3Dyes Abstract: Background: Altered mechanical properties of the heel pad have been implicated in the development of plantar heel pain. However, the in vivo properties of the heel pad during gait remain largely unexplored in this cohort. The aim of the current study was to characterise the bulk compressive properties of the heel pad in individuals with and without plantar heel pain while walking.Methods: The sagittal thickness and axial compressive strain of the heel pad were estimated in vivo from dynamic lateral foot radiographs acquired from nine subjects with unilateral plantar heel pain and an equivalent number of matched controls, while walking at their preferred speed. Compressive stress was derived from simultaneously acquired plantar pressure data. Principal viscoelastic parameters of t... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344463 Mon, 20 Apr 2009 17:57:47 +0100 2344463 http://www.medworm.com/index.php?rid=2344462&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000199%2Fabstract%3Frss%3Dyes Abstract: Background: Although extreme values of arch height have been associated with increased risk for overuse injury, knowledge is limited regarding the association between arch height and plantar pressure distributions during gait. The primary purpose of this study was to explore which plantar pressure measurements during gait were associated with static arch height and arch height index.Methods: Static arch height, arch height index, and dynamic plantar pressure distributions were collected for 1000 subjects (566 males, 434 females, 30.6 [SD 8.0] years, 171.1 [SD 9.3]cm, 76.9 [SD 14.7]kg). A hierarchical regression analysis was performed to determine the most parsimonious set of plantar pressure parameters associated with arch height. The predicted values were used to calculate dynam... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344462 Mon, 20 Apr 2009 17:57:41 +0100 2344462 http://www.medworm.com/index.php?rid=2344461&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000266%2Fabstract%3Frss%3Dyes This study provides a biomechanical rationale for medial displacement calcaneal osteotomy treatments for posterior tibial tendon dysfunction. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344461 Mon, 20 Apr 2009 17:57:40 +0100 2344461 http://www.medworm.com/index.php?rid=2344460&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000175%2Fabstract%3Frss%3Dyes Abstract: Background: Unreamed tibia nails with small diameters are increasingly used for fracture fixation. However, little is known about the fatigue strength of proximal and distal interlocking screws in those nails. To date, no data are available reporting on mechanical differences of solid compared to cannulated tibial nails. The aim of this study was to assess the fatigue strength of proximal and distal interlocking screws of solid and cannulated small diameter tibia nails.Methods: We created a distal tibia fracture model (AO/OTA 43 A3) using 16 Sawbones. After fracture stabilization with one of four different nail types (Expert Tibial Nail™, VersaNail™, T2 Tibial Nailing System™, Connex™), mechanical testing was performed in three loading series (40,000 cycles each) with inc... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344460 Mon, 20 Apr 2009 17:57:40 +0100 2344460 http://www.medworm.com/index.php?rid=2344459&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000291%2Fabstract%3Frss%3Dyes The objective of this study was to investigate the influence of walking speed on biomechanical variables associated with joint loading in persons with varying severities of medial compartment knee osteoarthritis.Methods: Twenty-one persons with moderate osteoarthritis (Kellgren–Lawrence score 2–3) and 13 persons with severe osteoarthritis (Kellgren–Lawrence score of 4) participated. Twenty-two persons without knee pain or radiographic evidence of arthritis comprised a healthy control group. Sagittal plane kinetics, knee adduction moment, sagittal plane knee excursion, ground reaction forces and knee joint reaction forces were calculated from three-dimensional motion analysis at 1.0m/s, self-selected and fastest tolerable walking speeds. Differences were analyzed using multivariate an... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344459 Mon, 20 Apr 2009 17:57:39 +0100 2344459 http://www.medworm.com/index.php?rid=2344458&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000217%2Fabstract%3Frss%3Dyes Abstract: Background: Persons with knee osteoarthritis demonstrate a reduction in knee joint excursion during loading response which is often coupled with a reduction in the moment acting to flex the knee. While these individual kinetic and kinematic changes are well documented, the interaction between changes in joint moment and changes in joint angle (dynamic joint stiffness) is not well understood in persons with knee osteoarthritis.Methods: Twelve persons with severe knee osteoarthritis (Kellgren–Lawrence score 4) and 22 persons with moderate knee osteoarthritis (Kellgren–Lawrence scores 2–3) were compared to a healthy control group (n=22). Dynamic knee joint stiffness was calculated during loading response and was defined as the slope of the linear regression when joint moment i... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344458 Mon, 20 Apr 2009 17:57:39 +0100 2344458 http://www.medworm.com/index.php?rid=2344457&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000230%2Fabstract%3Frss%3Dyes Abstract: Background: The hip transposition is firmly established in pelvic sarcoma surgery. However, the primary stability of the hip transposition has not been tested yet so that the mobilisation, respectively the immobilisation of the patient so far solely relied on the experience of the surgeon. The aim of this study was to test the primary stability reliably with the help of a model and to reveal possible differences in stability between currently used anchor systems (TwinFix® 6.5 and MITEK® SuperAnchor®).Methods: A biomechanical model of porcine sacra was developed to document the maximum load capacity (load to failure test) and the performance under cyclic load (100N, 200N, 350N, 700N, 1400N, each with 1000 cycles), 28 sacra were tested in total. Macroscopic damages, displacement... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344457 Mon, 20 Apr 2009 17:57:38 +0100 2344457 http://www.medworm.com/index.php?rid=2344456&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000278%2Fabstract%3Frss%3Dyes Abstract: Background: The purpose of this study was to elucidate relationships between quadriceps and hamstrings voluntary muscle fatigue and upper motor lesion impairments in cerebral palsy in order to gain a better understanding of their contribution to the observed fatigue resistance.Methods: Seventeen ambulatory subjects with cerebral palsy (mean age: 17.0, SD=4.8 years) were recruited. Quantitative measures of strength, spasticity, cocontraction, and stiffness for both muscle groups were collected on an isokinetic dynamometer and entered in a factor analysis. The resulting factors were used as independent variables in a multiple regression analysis with quadriceps and hamstrings fatigue as dependent variables.Findings: Five independent factors explained 90% of the variance. In order o... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344456 Mon, 20 Apr 2009 17:57:38 +0100 2344456 http://www.medworm.com/index.php?rid=2344455&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000229%2Fabstract%3Frss%3Dyes Abstract: Background: Fall-related injuries are multifaceted problems. One approach to identify the critical biomechanical factors is biodynamic simulation.Methods: A 2-degree-of-freedom discrete impact model was constructed through system identification and validated using experimental data in order to understand the dynamic interactions of various biomechanical parameters in bimanual forward fall arrests.Findings: The bimodal reaction force responses from the identified models had very small identification errors ( (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344455 Mon, 20 Apr 2009 17:57:37 +0100 2344455 http://www.medworm.com/index.php?rid=2344454&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000308%2Fabstract%3Frss%3Dyes Abstract: Background: Sudden trunk perturbations occur in various occupational and sport activities. Despite numerous measurement studies, no comprehensive modeling simulations have yet been attempted to investigate trunk biodynamics under sudden loading/unloading.Methods: Dynamic kinematics-driven approach was used to evaluate the temporal variation of trunk muscle forces, internal loads and stability before and after a sudden release of a posterior horizontal load. Measured post-disturbance trunk kinematics, as input, and muscle electromyography (EMG) activities, for qualitative validation, were considered.Findings: Computed agonist and antagonist muscle forces before and after release agreed well with reported EMG activities and demonstrated basic response characteristics such as activa... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344454 Mon, 20 Apr 2009 17:57:37 +0100 2344454 http://www.medworm.com/index.php?rid=2344453&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000254%2Fabstract%3Frss%3Dyes Abstract: In the last three decades it has become quite common to evaluate local muscle fatigue by means of surface electromyographic (sEMG) signal processing. A large number of studies have been performed yielding signal-based quantitative criteria of fatigue in primarily static but also in dynamic tasks. The non-invasive nature of this approach has been particularly appealing in areas like ergonomics and occupational biomechanics, to name just the most prominent ones. However, a correct appreciation of the findings concerned can only be obtained by judging both the scientific value and practical utility of methods while appreciating the corresponding advantages and limitations. The aim of this paper is to serve as a state of the art summary of this issue. The paper gives an overview of c... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344453 Mon, 20 Apr 2009 17:57:36 +0100 2344453 http://www.medworm.com/index.php?rid=2344452&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000242%2Fabstract%3Frss%3Dyes Abstract: Background: Detailed information about the loading of the knee joint is required for various investigations in total knee replacement. Up to now, gait analysis plus analytical musculo-skeletal models were used to calculate the forces and moments acting in the knee joint. Currently, all experimental and numerical pre-clinical tests rely on these indirect measurements which have limitations. The validation of these methods requires in vivo data; therefore, the purpose of this study was to provide in vivo loading data of the knee joint.Methods: A custom-made telemetric tibial tray was used to measure the three forces and three moments acting in the implant. This prosthesis was implanted into two subjects and measurements were obtained for a follow-up of 6 and 10months, respectively.... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344452 Mon, 20 Apr 2009 17:57:34 +0100 2344452 http://www.medworm.com/index.php?rid=2344451&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000618%2Fabstract%3Frss%3Dyes (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2344451 Mon, 20 Apr 2009 17:57:34 +0100 2344451 http://www.medworm.com/index.php?rid=2493628&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000576%2Fabstract%3Frss%3Dyes Abstract: Background: The posterior tibial slope of the knee is an issue in total knee arthroplasty. It has also been suggested to be a determinant for the difference in the incidence of anterior cruciate ligament rupture between males and females. The current literature features discrepancies in inter-individual variation in posterior slope and the effect of gender. This in vitro study was aimed at quantifying the inter-individual variations of the posterior tibial slope and the gender difference.Methods: The slope of the medial tibial plateau of 61 male and 44 female, bare human tibias was measured in three sagittal planes, separated by 5mm, with the use of a custom-made device. The effect of measurement location, gender and ethnicity was determined with analysis of variance.Findings: Th... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493628 Tue, 14 Apr 2009 23:00:00 +0100 2493628 http://www.medworm.com/index.php?rid=2493627&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000722%2Fabstract%3Frss%3Dyes Abstract: Background: The primary stability of a cementless implant is crucial to ensure long term stability through osseointegration. In the present study we have examined how subject specific finite element models can be used to evaluate the stability of a cementless femoral stem.Methods: Micromotion on the bone–implant interface of a cementless stem was measured experimentally in six human cadaver femurs. Subject specific finite element models were built from computed tomography of the same femurs, and used to simulate the same load scenario used experimentally.Findings: Both experimental measurements and numerical analyses showed a tendency of increased rotational stability for bigger implants. Good correlation was found between measurements and calculated values of axial rotation (R... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493627 Tue, 14 Apr 2009 23:00:00 +0100 2493627 http://www.medworm.com/index.php?rid=2493630&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS026800330900059X%2Fabstract%3Frss%3Dyes In conclusion, we showed that a program composed of 3 months of comprehensive exercise modulated the output of the postural response through a neural adjustment in the timing and amplitude of the muscular activation. (Source: Clinical Biomechanics) Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493630 Sun, 12 Apr 2009 23:00:00 +0100 2493630 http://www.medworm.com/index.php?rid=2493634&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000588%2Fabstract%3Frss%3Dyes Abstract: Background: It has been proposed that people with rheumatoid arthritis experience difficulties in postural control and activities of daily living such as walking. The aim of the study is to evaluate postural stability in rheumatoid arthritis patients.Method: A convenience sample of 19 rheumatoid arthritis patients (mean duration 13.1±9.2years) were aged matched with a non-rheumatoid group (n=21). Postural stability was measured using a force plate for anterior–posterior and mediolateral centre of pressure excursion for 30s with eyes closed and open. Patients also performed three walks at a self-selected speed and mean temporal–spatial parameters were recorded.Findings: Significant differences were observed between the groups in anterior–posterior centre of pressure excursi... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493634 Thu, 09 Apr 2009 23:00:00 +0100 2493634 http://www.medworm.com/index.php?rid=2493633&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000564%2Fabstract%3Frss%3Dyes Abstract: Background: Measuring the range of motion of the ankle joint can assist in accurate diagnosis of ankle laxity. A computed tomography-based stress-test (3D CT stress-test) was used that determines the three-dimensional position and orientation of tibial, calcaneal and talar bones. The goal was to establish a quantitative database of the normal ranges of motion of the talocrural and subtalar joints. A clinical case on suspected subtalar instability demonstrated the relevance the proposed method.Methods: The range of motion was measured for the ankle joints in vivo for 20 subjects using the 3D CT stress-test. Motion of the tibia and calcaneus relative to the talus for eight extreme foot positions were described by helical parameters.Findings: High consistency for finite helical axis... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493633 Tue, 07 Apr 2009 23:00:00 +0100 2493633 http://www.medworm.com/index.php?rid=2493626&cid=s_35400_31_f&fid=35400&url=http%3A%2F%2Fwww.clinbiomech.com%2Farticle%2FPIIS0268003309000515%2Fabstract%3Frss%3Dyes Abstract: Background: Reverse shoulder arthroplasty relies on its congruent ball/socket joint to restore shoulder function. For a simple ball/socket joint, as shown in total hip arthroplasty, range of motion decreases with the increase of articular constraint. We challenge here that this intuitive concept might not be held in reverse shoulder arthroplasty because of the effect of multiple concurrent factors.Methods: Abduction impingement-free arc of motion in reverse shoulder arthroplasty was examined with a virtual computer model. Six articular constraints, defined by normalized socket depths, were simulated. Four concurrent factors: glenosphere diameter, lateral offset of glenosphere from the glenoid surface, humeral neck-shaft angles, and locations of the glenosphere on the glenoid surf... Clinical Biomechanics journals http://www.medworm.com/rss/comments.php?id=2493626 Sun, 05 Apr 2009 23:00:00 +0100 2493626