Subject(s)
Arthroplasty, Replacement/instrumentation , Arthroplasty, Replacement/methods , Biocompatible Materials , Equipment Failure Analysis , Joint Prosthesis , Prosthesis Design , Arthroplasty, Replacement/trends , Biotechnology/instrumentation , Biotechnology/methods , Biotechnology/trends , HumansSubject(s)
Artificial Limbs , Gait/physiology , Biomechanical Phenomena , Humans , Leg , Posture/physiology , Prosthesis FittingSubject(s)
Cementation/adverse effects , Cementation/methods , Equipment Failure Analysis/methods , Femoral Fractures/etiology , Hip Prosthesis/adverse effects , Joint Instability/etiology , Prosthesis Design/methods , Bone Cements , Computer-Aided Design , Femoral Fractures/physiopathology , Femoral Fractures/prevention & control , Femur/injuries , Femur/physiopathology , Femur/surgery , Humans , Joint Instability/physiopathology , Joint Instability/prevention & control , Motion , Prosthesis Failure , Reproducibility of Results , Research Design , Sensitivity and Specificity , Technology Assessment, Biomedical/methods , Treatment Outcome , Weight-BearingSubject(s)
Equipment Failure Analysis/methods , Gait , Knee Prosthesis , Computer Simulation , Finite Element Analysis , HumansABSTRACT
In the present experiment we obtained the tensile properties of the human gastrocnemius tendon, a high-stressed tendon suitable for spring-like action during locomotion. Measurements were taken in vivo in six men. The gastrocnemius tendon elongation during tendon loading-unloading induced by muscle contraction-relaxation was measured using real-time ultrasonography. Tendon forces were calculated from the moment generated during isometric plantarflexion contraction, using tendon moment arm length data obtained in vivo with the tendon travel method. Tendon stiffness data were calculated from the slope of the tendon force-elongation curve, and were then normalized to the tendon's original dimensions, obtained from morphometric analysis of sonographs, to estimate the tendon Young's modulus. Mechanical hysteresis values were obtained from area calculations by numerical integration. The elongation of the tendon increased curvilinearly with the force acting upon it, from 1.7+/-1mm (0.8+/-0.3% strain) at 87.5+/-8.5 N to 11.1+/-3.1mm (4.9+/-1% strain) at 875+/-85 N. The tendon Young's modulus and mechanical hysteresis were 1.16+/-0.15 GPa and 18+/-3%, respectively. These values fall within the range of values obtained from in vitro experiments and are very similar to the respective values recently obtained from in vivo measurements in the less highly stressed human tibialis anterior tendon (1.2 GPa and 19%), thus indicating that the material properties of tendon are independent of physiological loading and function. Combining the present tendon force-elongation data with previously reported Achilles tendon force data recorded during walking indicates that the gastrocnemius tendon would provide approximately 6% of the total external work produced by the locomotor system. This estimate illustrates the contribution of passive elastic mechanisms on the economy and efficiency of walking. The contributions would be greater in more active exercise such as running.
Subject(s)
Achilles Tendon/diagnostic imaging , Achilles Tendon/physiology , Muscle, Skeletal/diagnostic imaging , Muscle, Skeletal/physiology , Adult , Elasticity , Humans , Locomotion/physiology , Male , Muscle Contraction/physiology , Nonlinear Dynamics , Physical Exertion/physiology , Reproducibility of Results , Sensitivity and Specificity , Stress, Mechanical , Tensile Strength/physiology , Torque , Ultrasonography , ViscosityABSTRACT
OBJECTIVE: To investigate the effect of independent practice of sitting balance as an addition to standard physiotherapy treatment for patients with stroke. DESIGN: Randomized controlled trial, using blocked randomization procedure with 2:1 ratio. SUBJECTS: Inpatients with diagnosis of stroke, having achieved one minute of independent sitting balance but not yet achieved 10 independent steps, and with no known previous disabilities, pathology or neurological deficit affecting mobility prior to stroke. INTERVENTION: A four-week regime of independent practice aimed at improving aspects of balance, as an addition to standard physiotherapy treatment based on the Bobath Approach. MAIN OUTCOME MEASURE: Proportion of patients achieving 'normal' symmetry of weight distribution during sitting, standing, rising to stand, sitting down, and reaching. RESULTS: Nineteen subjects were randomized to the control group; nine to the intervention group. There were no clinically significant differences in measured outcome between the groups. CONCLUSIONS: The regime of independent practice had no measured beneficial effect on the balance ability of patients with recently acquired stroke.
