Clinical biomechanics
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Clinical biomechanics · Mar 1998
The mechanical properties of human alar and transverse ligaments at slow and fast extension rates.
To study biomechanics and failure characteristics of the alar and transverse ligaments of the upper cervical spine at two different extension rates. DESIGN. IN VITRO: biomechanical study using human and alar and transverse ligament specimens. ⋯ Within the physiological limits, the strain and energy absorbed decreased to less than one tenth, while the stiffness increased to greater than ten times as the extension rate increased, for both the alar and transverse ligaments. When failed at the faster rate, the alar ligament, although weaker of the two, absorbed greater energy to failure because of its higher failure strain.
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Clinical biomechanics · Apr 1997
Analysis of plantar loading parameters pre and post surgical intervention for hallux vargus.
INTRODUCTION:: The purpose of the study was to compare range of motion (ROM) and plantar loading parameters pre and post surgical intervention for hallux valgus (HV). Fifteen female patients volunteered for the study, providing 27 feet with a diagnosis of moderate or severe HV deformity (greater than 26 degrees HV angle). All participants were screened by the same orthopaedic surgeon to ensure that no other foot deformities or neuromuscular diseases were present that would alter lower extremity biomechanics. ⋯ Dorsiflexion ROM for the MP joint were decreased post surgically but were still adequate for gait (Hetherington et al., 1990). Loading variables indicated that, post surgically, the foot was loaded more laterally with less load on the hallux. Further research is needed to assess if the lateral loading pattern continues long term after Chevron-Aikin Osteotomy surgical correction for HV.
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Clinical biomechanics · Jan 1997
Precision measurement of disc height, vertebral height and sagittal plane displacement from lateral radiographic views of the lumbar spine.
OBJECTIVE.: To compile a database of disc height, vertebral height and sagittal plane displacement from lateral radiographic views of the lumbar spine, valid for male and female subjects in the age range 16-57 years. The protocols used to measure these parameters compensate for distortion in central projection, off-centre position, axial rotation and lateral tilt of the spine as well as for variation in radiographic magnification and stature. STUDY DESIGN.: The study comprised designing and testing of measurement protocols, together with subsequent data collection from archive radiographs. ⋯ On average, height of lumbar vertebrae is larger in females than in males; height of lumbar discs is larger in males than in females and shows a minute dependence on age in males; in both genders, sagittal plane displacement increases, but only by a small amount, with age. CONCLUSIONS.: The new measurement protocols for disc height, vertebral height and sagittal plane displacement, together with the database of normative age-related values, permit quantitative assessment of the prevalence of pathological morphological changes in the human lumbar spine. The new method and the database will serve to explore the effect of potentially detrimental influences such as high spinal loading and to provide quantitative documentation of existing injury to vertebrae and discs in individual cases.
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Clinical biomechanics · Dec 1996
Precision measurement of segmental motion from flexion-extension radiographs of the lumbar spine.
To measure sagittal plane motion of lumbar vertebrae from lateral radiographic views. Previously identified factors of imprecision such as distortion in central projection, off-centre position, axial rotation, and lateral tilt of the spine were compensated. STUDY DESIGN: This study presents a new protocol to measure sagittal plane rotational and translational motion from lateral flexion-extension radiographs of the lumbar spine. ⋯ The results of this study show that precision of the measurement of rotational and translational motion can be considerably enhanced by making allowance for radiographic distortional effects and by minimizing subjective influence in the measurement procedure.
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Clinical biomechanics · Oct 1996
EMG activities of the quadratus lumborum and erector spinae muscles during flexion-relaxation and other motor tasks.
The aim of this study was to provide new information on the myoelectrical activation of the quadratus lumborum, the deep lateral and the superficial medial lumbar erector spinae, the psoas, and the iliacus muscles in various motor tasks. DESIGN: An intramuscular electromyographic study was performed. ⋯ In general, the activation of the investigated muscles showed a high degree of task specificity, where activation of a certain muscle was not always predictable from its anatomical arrangement and mechanical advantage.