Following transfemoral amputation, regaining functional mobility, particularly the ability to navigate curbs, ramps, long distances, and the ability to stand is challenging and often unattainable. Use of advanced prosthetic limb technology can dramatically influence mobility outcomes. The purpose of this study is to compare walking function in individuals with transfemoral amputations who are current users of the C-leg (micro-processor controlled prosthetic knee; current clinical standard) to function achieved when using the Bio Leg powered micro-processor prosthetic knee.

Although microprocessor-controlled knees (MPK) such as the C-Leg have demonstrated clear benefits over non-microprocessor-controlled prosthetic knees, it remains unclear whether powered knee assistance provides additional advantages in movement quality, metabolic efficiency, and limb loading during walking adaptability tasks.

This study directly addresses this gap by comparing mobility using the Bio Leg to mobility with the C-Leg using outcome measures that reflect real-world mobility challenges.

By generating objective evidence on whether powered knee assistance improves biomechanics, efficiency, and stability beyond that achieved with an established MPK, this study will inform prosthetic prescription, rehabilitation strategies, and payer decision-making. Given the growing population of individuals living with transfemoral amputation, identifying technologies that support safe, efficient, and confident mobility has important implications for community participation, long-term musculoskeletal health, and quality of life.

This study uses a within-subject repeated-measures design in which each participant is assessed under two conditions: current prosthesis and the Bio Leg prosthesis. All primary and secondary outcomes will be analyzed as within-participant differences, with each participant serving as their own control.

Inclusion Criteria:

• Adults 40 to 70 years of age
• Unilateral transfemoral amputation > 1 year
• K3 or K4 ambulator (based on the K classification system) and able to walk with no greater assistances than a single point cane
• Current microprocessor-controlled prosthesis (C-leg) user with > 6 months experience and able to walk without a device of using a single point cane
• Able to give informed consent

Exclusion Criteria:

• Severe cardiovascular condition or other disease limiting study participation
• Skin lesions or wounds, acute or unstable fracture, diagnosis of osteoarthritis or bone impairments affecting safe participation in walking activities
• Residual limb dysfunction (i.e. joint contracture) limiting mobility or study participation
• Pain that limits walking of participation in walking activities
• Current participation in rehabilitation to address walking function