Powered prosthetic feet do not decrease contralateral knee loads relative to energy storing and returning feet during walking in a functionally diverse cohort of individuals with unilateral transtibial limb loss

Among individuals with unilateral transtibial limb loss (UTTLL), contralateral knee osteoarthritis is a prevalent musculoskeletal condition that can greatly reduce long-term mobility and quality of life. While powered (POW) prosthetic feet may decrease contralateral knee loads during walking, a biomechanical risk factor for osteoarthritis, previous studies comparing POW to energy storing and returning (ESR) feet have been limited to relatively small (N=6–10), homogenous samples. Specifically, prior studies have included either younger, more novice ambulators (age: 25–38 years, 9–37 months ambulating) or older, more experienced ambulators (age: 37–51 years, 2–39 years since limb loss). In this study, we quantified the first peak and loading rate of contralateral limb vertical ground reaction forces (vGRF), knee adduction moments (KAM), and axial tibiofemoral contact forces (TCF) among a diverse cohort of 29 individuals with UTTLL walking with POW, ESR, and articulating ESR (ART) prosthetic feet (29–72 years, time since limb loss: 5–387 months). While we hypothesized that contralateral loads would be smaller with POW vs. ESR and ART feet, we found POW and ESR feet elicited similar loads and ART feet elicited the largest loads. While smaller prosthetic push-off powers explained larger contralateral knee loads for ART feet, the larger push-off powers of POW vs. ESR feet were not sufficient to produce load differences. From a large and diverse sample, these findings suggest prosthetic foot type alone may not mitigate contralateral knee osteoarthritis risk, with the caveat that loading measures captured in the laboratory may not reflect the knee's loading environment in daily life.