Biomechanic effects of a contralateral shoe-lift on walking with an immobilized knee.

OBJECTIVES A previous study demonstrated that when one knee is artificially immobilized, a contralateral shoe-lift improves the oxygen cost of walking. This study was undertaken to evaluate the kinematic and kinetic effects associated with this shoe-lift. DESIGN Motion analysis and force platform data were collected in subjects walking (1) normally, (2) with one knee immobilized, (3) with one knee immobilized and with a one-half-inch shoe-lift applied to the contralateral, nonimmobilized shoe, and (4) with a one-inch shoe-lift similarly applied. Kinematic and kinetic data from three trials of each condition were compared graphically and statistically using a repeated measures analysis of variance. SETTING A gait laboratory. SUBJECTS Eight able-bodied subjects without known neurologic or musculoskeletal problems. MAIN OUTCOME MEASURES Fifty-two peak kinematic and kinetic variables during various phases of the gait cycle. RESULTS Statistically significant differences (p < .05) between the normal and immobilized knee conditions were noted in 22 variables; however, significant differences between the immobilized knee conditions were found in only 4 variables. There were small improvements with the shoe-lifts toward normal in peak hip abduction, hip abduction at 20% to 30% of the gait cycle, and in peak knee extension moment on the nonimmobilized side. There was a small change away from normal in peak knee extension moment on the immobilized-side for the 1" shoe-lift. CONCLUSION Wearing a contralateral shoe-lift when one knee is immobilized is associated with only small changes in kinematic and kinetic parameters. The shoe-lift may slightly reduce the need for compensatory hip abduction and vaulting on the nonimmobilized side. Importantly, no adverse biomechanic effect from the shoe-lift was noted except for a slightly increased peak knee extension moment on the immobilized side found for the 1" but not the 1"/2 shoe-lift.