The goal of clinical trial is to assess an integrated, patient-centered strategy combining user preference-based prosthetic foot prescription and subsequent targeted physical therapy to maximize satisfaction and mobility outcomes for Veterans and others with lower limb loss. The main aims it will address are:

• Assess the effect of prosthetic foot selection based on experiential preference as determined using a variable stiffness foot on mobility and satisfaction
• Assess the effect of a targeted physical therapy intervention following preference-based foot selection on mobility, balance, and satisfaction? Participants will walk with an emulator prosthetic foot to experience three different conditions that emulate different commercial feet to determine their most- and least-preferred foot. Participants' satisfaction, perceived mobility, and functional mobility will be measured and compared between their most- and least-preferred feet using the corresponding commercial feet. Participants will then be randomly assigned to receive either the standard-of-care (control group) or personalized physical therapy intervention for eight weeks using that preferred prosthetic foot. Participants' satisfaction, mobility, and balance will be measured pre- and post-intervention.

Aim 1: Assess the effect of prosthetic foot selection based on experiential preference as determined using a variable stiffness foot on mobility and satisfaction. Baseline mobility and satisfaction of 50 Veterans with unilateral transtibial amputation (UTTA) will initially be evaluated with their currently prescribed prosthesis. Participants will then walk with the Variable-Stiffness Prosthetic Ankle (VSPA) Foot across real-world mobility scenarios inside and outside the laboratory. During this protocol, participants will experience three different VSPA Foot conditions that emulate different commercial feet to determine each participant's most- and least-preferred foot (with further opportunity for fine-tuning to determine the optimal stiffness category of their most preferred foot). Participants' satisfaction, perceived mobility, and functional mobility will be measured and compared between their most- and least-preferred feet using the corresponding commercial feet. Aim 2: Assess the effect of a targeted physical therapy (PT) intervention following preference-based foot selection on mobility, balance, and satisfaction. After a two-week, community-based accommodation period with their most preferred commercial foot, participants' satisfaction, perceived and functional mobility, and balance will be measured. Participants will then be randomly assigned to receive either the standard-of-care (control group) or personalized PT intervention that targets and addresses impairments in mobility and balance and patient-specific functional goals (intervention group). Following eight weeks of either standard-of-care or PT intervention, participants' satisfaction, mobility, and balance will again be measured and compared between groups (intervention vs. control) and across time periods (pre- vs. post-accommodation measurements).

Inclusion Criteria:

• Unilateral transtibial amputation;
• At least 6 months post-amputation;
• A comfortable-fitting prosthetic socket that can be used with endoskeletal components;
• Sufficient walking abilities to safely complete study activities.

Exclusion Criteria:

• Major contralateral limb amputation LLL on the contralateral limb;
• Currently receiving physical therapy related to gait training or prosthesis use.