Rationale and Objective: Transfemoral amputation or above-the-knee amputation results in the loss of two major lower-limb joints: the ankle and knee. Loss of active knee control is one factor that makes mobility extremely challenging for persons with transfemoral amputation. Current transfemoral prosthetic socket designs encase the hip joint and portions of the pelvis, limiting range of motion at the hip and compromising comfort. While current prosthetic sockets are reasonably functional for persons with amputation levels below the knee and for those persons with low to moderate levels of function, they provide limited functional restoration for those with higher levels of amputation, especially highly active individuals. Service persons with amputation present challenges that are different from the more typical older amputee with vascular problems. Individuals who enter the military are generally young and in excellent health prior to their combat-related injury. Many wounded soldiers wish to return to the level of activity they enjoyed before their injuries, including active duty. Therefore, they have much higher expectations of their function after amputation. Given the resources and time invested in training our military personnel and the substantial negative functional impact of a transfemoral amputation, providing these highly skilled, dedicated, and motivated individuals with the rehabilitation and prosthetic technology necessary to return to an active and fulfilling lifestyle, including continued service, is a desirable goal and worthwhile investment of resources. We have identified a new prosthetic socket design that requires further development to bring it to full maturity and deployment within the military environment. The socket design we propose to develop does not impinge on the pelvis when the hip is moved because it has lower edges than typical transfemoral sockets; the socket is as flexible as possible, allowing muscles to move comfortably within the socket as they contract during activity and to improve comfort during sitting; and the socket is held securely to the leg by suction from a vacuum pump, which makes for a firmer connection between the residual limb and prosthesis.

Applicability of the Research: The prosthetic socket technology in this proposal will enable clinicians to provide better prosthetic care and rehabilitation of highly active military service persons with transfemoral amputation. Increased comfort, hip range of motion, and connectivity between the residual limb and prosthesis will result in better functional performance for individuals with combat-related transfemoral amputations. Furthermore, improvements in socket comfort and connectivity can benefit all persons with transfemoral amputation, not just those who are highly active. Variants of the proposed socket design are being attempted by adventurous prosthetists but require research to bring the concept to full maturity and deployment within the demanding military environment. Traditional methods of prosthetic socket construction are not very robust. For example, it is possible to craft a socket that is rigid in some areas and flexible in other areas, but it is not possible to smoothly transition between the two. It is possible to specify the internal shape of a socket, but it is not possible to precisely control the thickness of the socket wall. Our research will use advanced manufacturing approaches and engineering analysis to develop a socket that provides greater comfort and increased durability to individuals with combat-related transfemoral amputation. Given the capabilities of today's manufacturing technology, we believe that a clinically relevant outcome can be achieved relatively quickly.

Contributions of This Study to Advancing Research: This study will advance research by developing a transfemoral prosthetic socket that challenges current understanding of how persons with transfemoral amputation walk using prostheses. It will allow us to explore not only new ideas for socket design but also new ideas, techniques, and materials for making prosthetic sockets using advanced manufacturing techniques.