Biomechanical accommodation to walking with an ankle-foot prosthesis: An exploratory analysis of novice users with transtibial limb loss within the first year of ambulation

Background: The way in which a person with limb loss interacts with a prosthesis changes over time; however, there remains a lack of guidance for defining accommodation to walking with a prosthesis, limiting consistency and generalizability of research.

Objective: To evaluate accommodations to walking with dynamic elastic response prosthetic ankle-foot devices among novice users with unilateral transtibial limb loss during the first year of ambulation.

Study design: This is a retrospective cohort study.

Methods: Prosthetic and intact ankle-foot mechanical power profiles and mechanical work during step-to-step transitions were calculated using the Unified Deformable model for 22 male individuals with limb loss at five time points within the first year of independent ambulation (0, 2, 4, 6, and 12 months). Subjects walked at a self-selected walking velocity and controlled walking velocity (CWV). Subjective measures included the Prosthetic Evaluation Questionnaire and the 36-Item Short-Form Health Survey.

Results: Self-selected walking velocity ranged from 1.24 ± 0.06 m/s at 0 month to 1.38 ± 0.04 m/s at 12 months, whereas CWV was 1.20 ± 0.02 m/s. At both velocities, positive work/peak power during prosthetic push-off trended upward until the 4-month time point. In addition, negative peak power during intact foot-strike seemed to qualitatively become less negative until 4 months. Positive work during intact push-off trended downward until 4 months at CWV, whereas positive peak power during intact push-off qualitatively became more positive at self-selected walking velocity.

Conclusions: These trends may partially indicate (biomechanical) accommodation to walking by appearance of a "plateau" at 4 months after initial ambulation with a prosthesis.