Lee, M & Maher, C 1995, 'Spinal Models', Physical Therapy, vol. 75, no. 7, pp. 638-641.
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Lee, M, Kelly, DW & Steven, GP 1995, 'A model of spine, ribcage and pelvic responses to a specific lumbar manipulative force in relaxed subjects', Journal of Biomechanics, vol. 28, no. 11, pp. 1403-1408.
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One class of manipulative techniques commonly used during assessment and treatment of spinal disorders involves the patient lying face down while the therapist slowly applies a posteroanterior force to a selected vertebra. The aim of this investigation was to develop a model which was capable of predicting the vertebral displacements resulting from such a manipulative force, applied to the lumbar spine. A linear three-dimensional finite element model was generated using both previously published and original data to define the geometry and material properties. The complete model included the ribcage, thoraco-lumbar spine and pelvis with their associated soft tissues. The model simulated the relaxed state in a normal subject so the muscle forces were assumed to be negligible. Sensitivity analysis suggested that if the model was to be used to simulate the behaviour of individual subjects, then the model dimensions and pelvic constraints should be matched to the particular subject. The model validity was studied by comparing the predicted responses with those that have been observed in living human subjects. The model predictions were found to be in good agreement with the mean observed human responses, with predicted displacements being within one standard deviation of the mean observed values. This agreement suggests that the model is useful for predicting the linear region responses to slowly applied lumbar posteroanterior forces. The simulations predicted that appreciable global vertebral displacements (up to 1.5 mm) and rotations (up to 1°) occurred as far away as the middle and lower thoracic spine during low lumbar loading. Intervertebral translations were predicted to be 1 mm or more at up to four intervertebral jonts away from the point of load application. Variation of direction of applied force was predicted to have small effects on displacement responses compared with loading at different lumbar levels. © 1995.
Viner, A & Lee, M 1995, 'Direction of manual force applied during assessment of stiffness in the lumbosacral spine.', J Manipulative Physiol Ther, vol. 18, no. 7, pp. 441-447.
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OBJECTIVE: To measure the angle of applied manual force during assessment of posteroanterior stiffness in the lumbosacral spine. DESIGN: Ten physiotherapists with bachelor's degrees in physiotherapy and postgraduate qualifications in manipulative physiotherapy assessed stiffness at 6 lumbosacral vertebral levels in a controlled order. Two pain free subjects acted as patients. SETTING: A university biomechanics laboratory. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Applied force vector angles in the sagittal plane. RESULTS: The physiotherapists all varied the direction of the force they applied so that it was directed slightly toward the feet at the lower vertebral levels and more toward the head as they moved up the spine. There was a significant difference between the direction of the applied force vector angles at each vertebral level (p < .0001). The direction of force used was also significantly different for the two patients (p = .0067). The forces used by the physiotherapists were applied in directions more vertical than if forces had been applied in directions perpendicular to the surface curves of the two patients. CONCLUSION: The direction of the force applied by the physiotherapists in this study when assessing posteroanterior stiffness varied significantly between vertebral levels and seemed to take into account the individual shape of the lumbosacral curve of each patient.
