Clinical biomechanics
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Clinical biomechanics · Mar 2011
Long-term functional implications of the iatrogenic rotational malalignment of healed diaphyseal femur fractures following intramedullary nailing.
The long-term functional implications for patients with iatrogenic femoral malrotation following femoral intramedullary nail fixation remain unclear. This study examined the extent and direction of rotational alignment of the femur treated with intramedullary nail fixation and its long-term functional effects on patients' standing, walking, and subjective outcome. ⋯ Patients can compensate for even significant femoral malrotation and tolerate it well. External femoral malrotation appears to be better compensated/tolerated than internal malrotation.
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Clinical biomechanics · Mar 2011
Comparative StudyBiomechanical evaluation of fixation strength of conventional and expansive pedicle screws with or without calcium based cement augmentation.
The expansive pedicle screw was originally developed to be installed in the bone of compromised quality, but there are some concerns whether it can provide enough fixation strength in the spine with osteoporosis or severe osteoporosis. ⋯ Our results demonstrate that (i) the expansive pedicle screw appears feasible and safe in either osteopenic or osteoporotic spine; (ii) calcium based cement augmentation can offer improved initial fixation strength of pedicle screws.; and (iii) no screw placement protocol we examined is efficacious in the bone at the severely osteoporotic level.
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Clinical biomechanics · Mar 2011
The effects of prosthetic ankle dorsiflexion and energy return on below-knee amputee leg loading.
Prosthetic devices are intended to return lower limb amputees to their pre-amputation functional status. However, prosthetic devices designed for unilateral below-knee amputees have yet to completely restore the biomechanical functions normally provided by the ankle muscles, leading to gait asymmetries and increased reliance on their intact leg. In an effort to improve amputee gait, energy storage and return feet have been developed that store mechanical energy in elastic structures in early to mid-stance and return it in late stance. However, little is known regarding how ankle compliance and the level of energy return influences walking mechanics. The purpose of this study was to identify the influence of prosthetic ankle dorsiflexion and energy storage and return on leg loading during steady-state walking. ⋯ These results provide insight into the relationships between ankle dorsiflexion, energy storage and return, and leg loading, which may lead to more effective prosthetic devices to improve amputee gait.
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Clinical biomechanics · Feb 2011
Alterations in joint kinematics during walking following hamstring and patellar tendon anterior cruciate ligament reconstruction surgery.
Previous research has shown that patients with anterior cruciate ligament reconstruction have altered movement patterns in the reconstructed knee during walking. In the sagittal plane, graft specific changes in knee joint motion have been reported between hamstring and patellar tendon anterior cruciate ligament reconstruction grafts. This study examined the secondary planes of movement during walking in anterior cruciate ligament reconstructed knees to evaluate the influences of graft type (hamstring or patellar tendon) and control condition (control group or contralateral knee). ⋯ The results show that there are differences in tibial rotation during walking in anterior cruciate ligament reconstructed knees compared to both the contralateral knee and uninjured control group. These kinematic alterations may relate to the high incidence of knee osteoarthritis observed in this population over time. Reduced varus in the hamstring group may relate to the graft harvest.
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Clinical biomechanics · Jan 2011
Correlations between strength and quantitative computed tomography measurement of callus mineralization in experimental tibial fractures.
the evaluation of fracture healing in the clinic has not changed significantly during the past few decades, despite the development of modern tissue-imaging tools. Recent publications have reported significant and interesting associations between biomechanical properties and quantitative computed tomography data of fractures and grafts. We therefore studied the correlations between the strength and segmented quantitative computed tomography data of tibial diaphyseal fractures. ⋯ quantitative computed tomography was used to quantify characteristic secondary healing. The observed correlations indicate that biomechanically important mineralization can be measured by quantitative computed tomography in the early phase of healing in flexibly fixed fractures.