Clinical biomechanics
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Clinical biomechanics · Jan 2017
Influence of different sizes of composite femora on the biomechanical behavior of cementless hip prosthesis.
For the biomechanical evaluation of cementless stems different sizes of composite femurs have been used in the literature. However, the impact of different specimen sizes on test results is unknown. ⋯ Specimen size seems to be a minor influence factor for biomechanical evaluation of cementless stems. However, the small composite femur is less suitable for biomechanical testing since this size failed under physiological adapted loads. For the CLS Spotorno osseous integration is unlikely at the tip of the stem and the tendency for stress shielding is the highest at the level of the lesser trochanter.
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Clinical biomechanics · Dec 2016
Characteristics of thoracic and lumbar movements during gait in lumbar spinal stenosis patients before and after decompression surgery.
Although gait analysis has been previously conducted for lumbar spinal stenosis patients, the vertebral segmental movements, such as of the thoracic and lumbar regions, and whether the spinal movement during gait changes after decompression surgery remain unclear. ⋯ The epidural pressure of lumbar spinal stenosis patients is known to be higher than that of normal subjects during gait, and to decrease during walking with lumbar flexion. Preoperatively, smaller thoracic and lumbar flexion movements during gait relative to the standing position cannot decrease epidural pressure; as a result, severe leg pain might be induced.
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Clinical biomechanics · Nov 2016
How does implant distribution affect 3D correction and bone-screw forces in thoracic adolescent idiopathic scoliosis spinal instrumentation?
Optimal implant densities and configurations for thoracic spine instrumentation to treat adolescent idiopathic scoliosis remain unknown. The objective was to computationally assess the biomechanical effects of implant distribution on 3D curve correction and bone-implant forces. ⋯ Low-density constructs, with implants mainly placed on the concave side, resulted in similar simulated curve correction as the higher-density patterns. Increasing the number of implants allows for only limited improvement of 3D correction and overconstrains the instrumentation construct, resulting in increased forces on the implants.
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Clinical biomechanics · Oct 2016
Role of the fibula in the stability of diaphyseal tibial fractures fixed by intramedullary nailing.
For tibial fractures, the decision to fix a concomitant fibular fracture is undertaken on a case-by-case basis. To aid in this clinical decision-making process, we investigated whether loss of integrity of the fibula significantly destabilises midshaft tibial fractures, whether fixation of the fibula restores stability to the tibia, and whether removal of the fibula and interosseous membrane for expediency in biomechanical testing significantly influences tibial interfragmentary mechanics. ⋯ These results suggest that fixation of the fibula may not contribute significantly to the stability of diaphyseal tibial fractures and should not be undertaken unless otherwise clinically indicated. For testing purposes, load-sharing through the interosseous membrane contributes significantly to overall construct mechanics, especially in torsion, and we recommend preservation of these structures when possible.
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Clinical biomechanics · Aug 2016
A radiographic assessment of lumbar spine posture in four different upright standing positions.
Approximately 50% of a sample population will develop prolonged standing induced low back pain. The cause of this pain may be due to their lumbar spine posture. The purpose of this study was to investigate differences in lumbar posture between 17 participants categorized as a pain or non-pain developers during level ground standing. A secondary purpose was to evaluate the influence of two standing aids (an elevated surface to act as a foot rest and declined sloped surface) on lumbopelvic posture. ⋯ Potentially successful postures for eliminating low back pain during prolonged standing mainly influence the lower lumbar lordosis. Future work should assess the influence of hip posture on low back pain development during standing.