Adjustable Prosthetic Sockets for Individuals With Lower Limb Amputation

Plain-language summary

Each year, around 1500 Veterans join the 623,000 Americans who live with a lower limb amputation. Many of these Veterans choose the arduous path of rehabilitation to remain ambulatory, a process that includes the prescription of a lower limb prosthesis. Much relies on the goodness of fit of their prosthesis. A good fit feels comfortable and enables a variety of ambulatory activities. A poor fit results in discomfort, often accompanied by chronic skin issues, and activities of daily living are curtailed. Conventional prosthetic sockets are custom-built by a skilled prosthetist, carefully formed to fit the Veteran's residual limb, and good fits can usually be obtained. These sockets are rigid, fixed shape structures with the robustness of a bulldozer, built for sustained, heavy-duty action. Unfortunately, the shape of an individual's residual limb can change over time, such that a good fit eventually becomes poor. One estimate suggests a new below-knee socket is needed every three and a half years. The expense of replacing sockets that no longer fit is not insignificant. Medicare expenditures for replacement of existing below-knee sockets and associated components were estimated at $50M in 2017. Importantly, Medicare is estimated to be only 20% of the market, suggesting the estimated expenditure for the entire population with lower limb amputations is likely to be meaningfully larger. A good fitting prosthesis that maintains its fit over time would serve Veterans well. A potential solution that could make a good fit last longer is an adjustable prosthetic socket. While little evidence is available to support prescription practice, the Centers for Medicare and Medicaid Services (CMS) recently authorized reimbursement for adjustable prosthetic sockets, suggesting a compelling need for such a product. To investigate the potential for deleterious effects and how Veterans might use adjustable prosthetic sockets, the aim of this research is to determine the pressure applied to the residual limb by an adjustable prosthetic socket during activities of varying intensity and the activities that induce adjustments. A laboratory-based human subject experiment will be conducted using a custom sensor placed inside the adjustable panel of a study-provided adjustable prosthetic socket. Participants will acclimate to the adjustable prosthetic socket for two weeks in the field, then return to the laboratory to perform seven activities. The pressure inside the prosthesis will be measured during these activities. Participants will also report how tight their socket feels after each activity.

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Trial details