Clinical biomechanics
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Clinical biomechanics · Sep 2014
Comparative StudyComparison of two different Radiostereometric analysis (RSA) systems with markerless elementary geometrical shape modeling for the measurement of stem migration.
Radiostereometric analysis (RSA) is the gold standard of measurement for in vivo 3D implants migration. ⋯ Marker-based RSA has high precision in all planes, independent of the system used. Elementary geometrical shape RSA is inferior in out-of-plane migration.
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Clinical biomechanics · Sep 2014
Single level lumbar laminectomy alters segmental biomechanical behavior without affecting adjacent segments.
Degenerative lumbar spinal stenosis causes neurological symptoms due to neural compression. Lumbar laminectomy is a commonly used treatment for symptomatic degenerative spinal stenosis. However, it is unknown if and to what extent single level laminectomy affects the range of motion and stiffness of treated and adjacent segments. An increase in range of motion and a decrease in stiffness are possible predictors of post-operative spondylolisthesis or spinal failure. ⋯ The increase in range of motion of 7-12% does not seem to indicate the use of additional instrumentation to stabilize the lumbar spine. If instrumentation is still considered in a patient, its primary focus should be on re-stabilizing only the treated segment level.
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We investigated mechanisms of axis ring fractures due to simulated head impacts. ⋯ We observed asymmetrical fractures of the axis ring including fractures of the superior and inferior facets, laminae, posterior wall of the vertebral body, pars interarticularis, and pedicles. The fracture patterns were related to the morphology of the axis as a transitional vertebra of the upper cervical spine. Understanding the mechanisms of axis ring fractures may help in choosing the optimal reduction technique and stabilization method based upon the specific fracture pattern.
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Clinical biomechanics · Sep 2014
Trunk muscle involvement is most critical for the loss of balance control in patients with facioscapulohumeral muscular dystrophy.
Although it is known that muscle weakness is a major cause of postural instability and leads to an increased incidence of falls in patients with neuromuscular disease, the relative contribution of lower extremity and trunk muscle weakness to postural instability has not been studied well. ⋯ These findings indicate that trunk muscle involvement is most critical for loss of sagittal-plane postural balance in patients with facioscapulohumeral muscular dystrophy. This insight may help to develop rehabilitation strategies to prevent these patients from falling.