Isokinetic performance after total hip replacement

Abstract

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.