Human-Centered Design Trade-offs for Semi-Powered Knee Prostheses: A Review

For many decades, developments of knee prostheses have shown a dichotomy regarding fundamental working principles. The industry has mainly emphasized on quasi-passive hydraulic solutions, whereas most research works have focused on powered devices, employing electric actuation. The former have an energetically passive effect at the knee joint, for which they often lack in providing versatility and movement robustness for the wearer. Powered prostheses can address these deficiencies, but are often rejected as they struggle to fulfill other user needs (e.g., weight and acoustic noise). Correspondingly, recent studies have emerged that attempt to significantly attenuate the deficiencies of fully powered prosthesis knees, partially sacrificing on device versatility. Recognizing the state-of-the art difficulties in balancing active assistance and user needs fulfilment, this work analyses human-centered design perspectives and their prospects for prosthetic development, in light of the often diverging user needs. We conclude that various types of both explored and yet unexplored semi-powered solutions may have the potential to provide the better trade-off between quasi-passive and fully powered prosthetic devices.