A study published online December 24, 2017, in the journal Disability and Rehabilitation: Assistive Technology depicted how people with above-knee amputations maintained stable gait over a variety of surfaces, including downhill and uphill, top-cross- and bottom-cross-slopes, medial-lateral translations, rolling hills, and simulated rocky surfaces.
Ten people with above-knee amputations and ten without amputations walked in a virtual environment with level, sloped, and simulated uneven surfaces on a self-paced treadmill. As part of the study, stability was quantified using medial-lateral margin of stability (ML-MoS), step parameters, and gait variability (standard deviations for speed, temporal-spatial parameters, foot clearance and root-mean-square of medial-lateral trunk acceleration).
Results showed that each of the 20 subjects adapted to nonlevel conditions by changing their walking speed, step width, and foot clearance. Variability for most parameters increased across conditions, compared to level, the study showed. Those with amputations walked slower than the able-bodied subjects by taking shorter, wider, and longer duration steps (most differences were related to speed). ML-MoS did not change compared to level; however, ML-MoS was greater on the side with the prosthesis than either the intact side or the nonprosthetic limbs, the study showed. Foot clearance and root-mean-square of medial-lateral trunk acceleration were greater on the prosthetic side than the intact side and the nonprosthetic limbs. The above-knee amputation group also had more trunk motion variability on the prosthetic side than the subjects without amputation, which could be related to prosthetic fit, the study found.