Mechanics of ambulation with standard and spring-loaded crutches.

OBJECTIVE To compare kinetic measures and spatiotemporal variables assessed during walking with standard axillary crutches and spring-loaded crutches. DESIGN A repeated-measures design in which healthy subjects walked with both standard and spring-loaded crutches. SETTING Biomechanics research laboratory. PARTICIPANTS Ten healthy young adult volunteers participated. Only female volunteers between 154.9 and 175.3 cm in stature were selected to fit the size of the crutches used. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES The main outcome measures were kinetic variables such as ground reaction force, rate of force rise, and impulse and spatiotemporal variables such as stride length, stride time, and percentage of stride spent in stance. RESULTS The rate of ground reaction force rise and impulse of the ground reaction force (both P<.001) were reduced by 33% and 13% to 26%, respectively, but the peak ground reaction force was slightly greater (P=.001) with spring-loaded crutches. The stride time was increased with spring-loaded crutches (P=.005), but the stride length did not differ significantly (P=.465). CONCLUSIONS The use of spring-loaded crutches altered the mechanics of crutch gait in ways that are likely to reduce overuse injury in crutch users. Further study of spring-loaded crutches is warranted, especially with respect to their energetic efficiency.