Two case studies of in-socket pressure characteristics for passive and active transtibial prostheses.

BACKGROUND: While adaptive and powered prosthetic ankles provide benefits for those with transtibial amputation, their impact on socket pressures and the role of user acclimation remain unclear. This case series measured in-socket pressures across different prosthetic feet, acclimation periods, and activities to understand device- and task-specific residual limb loadings. METHODS: Two unilateral transtibial prosthesis users completed walking trials with three prosthetic foot types, passive standard-of-care, PROPRIO (Össur), and Empower (Ottobock), across five walking activities: level walking and ramp and stair ascent/descent. Socket pressures were recorded at eight limb regions after acclimation periods of 15-30 min and 4 weeks. Peak pressures and pressure-time integrals were analyzed by device, acclimation, and activity for each subject. FINDINGS: Pressure responses were highly individualized and region-specific. Subject 1 exhibited elevated pressures during ramp ascent and stair descent, particularly at the anterior middle and posterior lateral regions. Acclimation effects included decreased pressure over time with Empower and PROPRIO. Subject 2 showed the highest pressures during level walking and ramp ascent, with Empower producing the lowest values, but no significant changes after acclimation. For neither subject did use of a powered device elevate pressures. INTERPRETATION: As a two-case exploratory study, findings emphasize individualized device and acclimation effects rather than population-level conclusions. Results suggest in-socket pressures depend on individual gait mechanics, task demands, and adaptation capacity. These observations support personalized fitting, multi-task testing, and adequate acclimation when evaluating advanced prosthetic feet.