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OBJECTIVE: To evaluate differences in isokinetic hip flexion, extension, and abduction muscle performance of operated vs. nonoperated hips in older adults who have undergone elective, unilateral, total hip replacement (THR) surgery and completed rehabilitation. DESIGN: Quasi-experimental study using a nonequivalent posttest-only control group design, comprising 20 unilateral THR patients and a convenience sample of 22 healthy older adults. THR patients participated between 4 and 5 mos after surgery. THR subjects received an average of 13 outpatient or home-based physical therapy sessions. Isokinetic muscle strength and fatigue was assessed through measurement of hip peak torque per body weight, total work, and average power using a robotic dynamometer. RESULTS: Comparisons of THR subjects' operated vs. nonoperated hips showed no significant differences in isokinetic performance for any of the examined variables. THR subjects' operated hips generated significantly less peak torque per body weight, total work, and average power across all exercises as compared with a population of healthy subjects. CONCLUSIONS: THR subjects' operated and nonoperated hips showed similar biomechanical performance. THR patients are not being restored to the same level of strength and muscular endurance as compared with a population of healthy adults. These findings may be useful in providing a preliminary rationale for revising current approaches in THR rehabilitation protocols. [ABSTRACT FROM AUTHOR]

The quality of life of patients relying on electrically powered artificial organs is currently restricted by the limited energy availability provided by portable batteries. As these patients become increasingly ambulatory, and are developing more active lifestyles, this limitation grows more apparent. Coincidentally, these patients may themselves be capable of generating electrical power as a consequence of their physical activity. Extraction of this latent autologous energy could, in turn, be used to augment charging of internal batteries--thus untethering the patient from external power for extended periods of time. In this study, the viability of deriving energy associated with natural human ambulation has been evaluated. The kinematic components of gait were evaluated to identify the largest useful forces and moments that may be harnessed as an energy source, while presenting minimal "perceived" work for the patient. It was found that the ground reaction forces associated with the heel strike and toe-off phases of the gait represent the greatest potential for usable energy. This study uses a piezoelectric array within the midsole of the shoe for the conversion of mechanical to electric energy. This power could then be easily coupled in tandem with existing transcutaneous transformers for augmenting or temporarily replacing external power sources.