The Effects of Slope-Adaptive Prosthetic Ankle-Feet on Sloped Gait Performance and Quality in Unilateral Transtibial Prosthesis Users: A Scoping Review

Abstract

Introduction In nonimpaired human locomotion, sagittal-plane slope adaptation of the ankle-foot complex is a function driven by neuromotor control to support upright posture and forward ambulation. Loss of this adaptation due to transtibial amputation can lead to instability and compensatory motions as most commercially available prosthetic feet do not permit automatic slope adjustments. A selection of slope-adaptive ankle-feet (SAAF) has been developed to promote biomimetic ankle motion while ambulating over slopes. This review evaluated the current literature to assess the effects of SAAF prostheses on sloped gait performance in unilateral transtibial prosthesis users. Methods Four databases (PubMed, Embase, CINAHL, IEEE Xplore) were searched on April 28, 2022, for relevant articles. Search keywords covered the general terms “transtibial,” “amputation,” “slope,” “adaptive,” and “gait,” and included articles comparing an SAAF prosthesis to a non-SAAF prosthesis condition. Data were extracted for analysis, and results were grouped according to outcomes to identify trends and aid interpretation of slope adaptation effects on gait. Results Of the 672 articles screened, 24 met the selection criteria and were included in this review, published between 2009 and 2022. The non-SAAF condition included dynamic response feet and SAAF prostheses with the adaptability function inactive. Outcomes included biomechanical variables (joint dynamics, gait symmetry, toe clearance), clinical outcome measures, and energy expenditure. All SAAF demonstrated some form of foot-ankle slope gradient adaptability, but effects on other joint dynamics were inconsistent. Minimum toe clearance during incline and decline walking was greater when using SAAF compared with non-SAAF in all reporting studies. Conclusions Results generally suggest improvements in gait quality, comfort, and safety with use of SAAF compared with non-SAAF during sloped walking. However, variations in tested SAAF and walking gradients across studies highlight the need for research to elucidate walking condition effects and advantages of specific designs. Clinical Relevance Slope-adaptive prosthetic ankle-feet may improve user gait quality and comfort and enhance gait safety by increasing minimum toe clearance. Patients who encounter slopes regularly should be considered as potential users of SAAF if indicated appropriately.