The effects of slope-adaptive prosthetic feet on sloped gait performance and quality in unilateral transtibial prosthesis users: A scoping review.

Introduction: In non-impaired human locomotion, sagittal-plane slope adaptation of the foot-ankle complex is a volitional 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 feet (SAF) have been developed to promote biomimetic ankle motion while ambulating over slopes. This review evaluated the current literature to assess the effects of SAF 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 a SAF prosthesis to a non-SAF 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-SAF condition included dynamic response feet and SAF prostheses with the adaptability function inactive. Outcomes included biomechanical variables (joint dynamics, gait symmetry, toe clearance), clinical outcome measures, and energy expenditure. All SAF 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 SAF compared to non-SAF in all reporting studies. Conclusions: Results generally suggest improvements in gait quality, comfort, and safety with use of SAF compared to non-SAF during slope walking. However, variations in tested SAF 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 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 SAF if indicated appropriately.