Most previous studies on running mechanics in amputees have used prostheses originally designed for walking, and those that have looked at running mechanics using prostheses designed for running have focused on sprinting. Because submaximal-speed running is common in day-to-day and sporting activities, researchers sought to determine how lower extremity joint moments change throughout the gait cycle when running with running-specific prostheses (RSPs) under different speed constraints.
Eight individuals with unilateral transtibial amputations and 8 control subjects with no amputations ran at 3 constant velocities. The researchers found that, compared with the intact limb, the prosthetic limb generated significantly greater peak ankle plantar flexion moments and smaller peak ankle varus, knee stance extension, knee swing flexion, knee internal rotation, hip stance flexion, hip swing flexion, hip swing extension, hip valgus, and hip external rotation moments. They observed that the intact limb had greater peak hip external rotation moments than control limbs, but all other peak moments were similar between these limbs. Increases in peak hip stance and knee swing flexion moments associated with speed were greater in the intact limb than the prosthetic.
The researchers concluded that the intact limb knee and hip joints generated greater peak moments than the prosthetic limb in all 3 planes of motion, suggesting a greater reliance on the intact limb during running. However, with the exception of hip internal rotation moments, the intact limb generated similar peak moment values to the control limbs, suggesting that the intact limb is not overloaded when individuals with lower extremity amputation run with RSPs. Only the hip peak stance flexion moment and knee swing flexion moment increases associated with speed were greater in the intact limb than the prosthetic limb, which they observe is likely a result of the greater joint accelerations and inertial properties in the intact limb. The researchers noted that research on potential functional differences between individuals with congenital vs traumatic amputations would be useful.
Baum BS, Hobara H, Koh K, et al. Amputee locomotion: Joint moment adaptations to running speed using running-specific prostheses after unilateral transtibial amputation. Am J Phys Med Rehabil. 2018 Feb 5. doi: 10.1097/PHM.0000000000000905. [Epub ahead of print].