Adjustable Prosthetic Sockets for Individuals With Lower Limb Amputation

Prosthetic sockets enabling ambulatory mobility of Veterans with lower limb amputation are typically rigid, overly strong structural elements of fixed shape that act as the interface between the body and the environment. A Veteran's prosthetic socket is bespoke; it is meant to fit one person and one person only. Changes in fit after the provision of a prosthesis are more common than not. Changes related to body mass, muscle atrophy, or personal fitness can happen over months while changes due to diet or diabetic complications can happen over hours. If the mismatch in shape between the residual limb and socket is small, the Veteran can manage the difference by donning or doffing residual limb socks. The approach is not ideal as some patients are more inclined to adopt the practice than others. If the mismatch in shape is large, a new prosthetic socket is usually required. Whether small or large, failure to manage changes can negatively affect their use of the prosthesis and the health of their residual limb. Despite its limitations, the fixed-shaped prosthetic socket has been the standard-of-care for decades. However, a potentially significant event occurred in April 2024 when the Centers for Medicare and Medicaid Services (CMS) authorized reimbursement for adjustable prosthetic sockets. While the new authorization enables payment for its provision, there is little evidence to aid patients, providers, and payers in understanding the potential outcomes of prescribing an adjustable prosthetic socket. The purpose of this research is to discover how Veterans use adjustable prosthetic sockets by measuring the pressure applied to the residual limb by an adjustable prosthetic socket during activities of varying intensity and identify what activities might induce an adjustment. The investigators will recruit ambulatory Veterans with unilateral transtibial amputations (n = 25) and fit them with an adjustable prosthetic socket. Participants will wear an instrumented adjustable prosthetic socket after wearing a non-instrumented duplicate adjustable prosthetic socket for two weeks. Participants will be allowed to walk about for 5 to 10 minutes while the research prosthetist checks the fit and alignment of the study prosthesis. Pressure measurements will then be collected while sitting, standing, and walking. The standing and walking activities will be performed in random order, interspersed with 1-minute seated rests where the participant will release the adjustable panel pressure. The walking trials will be performed on a treadmill. * Seated rest 5 min * Random order with 1 min seated rest between each: * Stand 1 min * Walk self-selected speed 1 min * Walk up 10% slope at self-selected speed 1 min * Walk down 10% slope at self-selected speed 1 min * Walk 15% faster than self-selected speed 1 min * Walk self-selected speed 10 min Just prior to the beginning of each activity, the participant will told what the next activity is and prompted to adjust their socket accordingly. Participants will also be free to make adjustments during an activity. In this situation, the duration of the activity will be extended such that 1 minute of activity remains at the new adjustment setting. At the end of each activity, tightness will be assessed using a survey question. Specifically, after each activity, the investigators will ask each participant to rate the tightness of their adjustable prosthetic socket at the moment on a 0 to 10 scale. In general, the investigators hypothesize that the pressure applied to the residual limb will depend on the activity, as will the tightness.