Transfemoral Amputee Osseointegration Study (TFAOS)

Background: Transfemoral amputees are currently an underserved population. Many are young, otherwise healthy individuals with amputations due to combat trauma or tumors. Patients with very high amputations or unusual anatomy often have difficulty wearing an external socket and using a prosthesis, which adversely affects both quality of life and productivity in society. OPRA (Osseointegrated Prostheses for the Rehabilitation of Amputees) is an implant system for direct skeletal anchorage of amputation prostheses. OPRA constitutes an alternative for amputees when treatment with socket prostheses is burdensome, painful, or otherwise insufficient. OPRA is based on the method of osseointegration (OI), implying direct contact between bone tissue and titanium implants and includes a supervised rehabilitation schedule. The system consists of a bone anchoring device (fixture) and a modular skin-penetrating device (abutment) that can be changed in the case of superficial infection or mechanical wear. The fixture is surgically inserted and after a healing time of 3 months, the abutment is connected to the fixture. The amputation prosthesis is then attached directly to the external part of the abutment via an appropriate force-limiting device. Objective/Hypothesis: (1) The OPRA system will be safe when used to treat the unique combat-related amputee population and civilian transfemoral amputees. (2) The OPRA system will result in improved pain and functional scores for combat-related and civilian transfemoral amputees. (3) Function and pain scores of OI transfemoral patients will be superior to scores obtained prior to OI. (4) Function and pain scores of osseointegrated transfemoral patients will be at least similar to patients who are content with their socket-based suspension mechanisms. Specific Aims: (1) To determine the safety profile of bone anchored, percutaneous transfemoral prostheses in a US population (using outcomes such as any adverse event, infection, revision of the implant, and removal of implant). (2) To determine the change in prosthetic use from standard external sockets to the bone-anchored, percutaneous prostheses using the QTFA prosthetic use score (a validated, self-reported questionnaire for transfemoral amputees). (3) To determine the change in transfemoral amputee-specific outcomes using the remaining QTFA domains and OPUS score (orthotics and prosthetics user survey). (4) To determine the change in health-related quality of life using the SF36 and PROMIS® questionnaires from an external socket to 2 years following percutaneous prosthetic implantation. (5) To determine the change in energy expenditure and gait symmetry from using a standard external socket to the percutaneous, bone-anchored prosthesis at 2 years. Study Design: This multicenter, prospective clinical investigation will be conducted at Walter Reed and University of California, San Francisco. The focus will be to evaluate the OPRA transfemoral implant (Food and Drug Administration approved H080004 HUD#080197). We will evaluate “before and after” changes in functional status using several measures validated in lower extremity amputees, including the Transfemoral Questionnaire for Transfemoral Amputees (QTFA) as well as the VASQL and PROMIS® Pain Behavior, Pain Interference, and Physical Function Lower Extremity. Twenty study participants will be enrolled at each site. To be eligible, prospective enrollees must have or expect significant problems with conventional socket-based prostheses. Patients with inadequate skeletal anatomy, obesity, or those who are not likely to complete the rehabilitation protocol will be excluded. During the follow-up period, the patients will be regularly assessed. Clinical and radiological assessments after completion of the surgical treatment will be performed preoperatively, in connection with the surgical procedures and at 3, 6, 12, and 24 months after completion of the surgical treatment. In addition, gait analysis and energy expenditure analysis will be performed at baseline and at 24 months. Military Relevance: The recent conflicts in the Middle East have contributed over 450 new amputees over 5 years to this population of the nearly 1,700,000 amputees living in the US currently. Most of these are caused by trauma, and more than 85% of those who undergo amputation due to combat-related injury are under 35. The majority of our wounded Service members are young, fit, and engage in active lifestyles. Despite dramatic improvements in socket fit and prosthetic designing leading to improved functional outcomes to many amputees, individuals with high transfemoral amputations continue to have difficulty wearing an external socket due to a short or irregular residual limb. This translates to infrequent prosthesis wear and poor functional outcomes. Currently about 18.5% of all amputees are at the transfemoral level. It is estimated that nearly one-third have difficulty wearing a socket or discomfort in the socket. This is often due to wounds, skin irritation, pain, or a short residual limb that cannot easily fit into a socket. Limiting motion at the socket-skin interface and providing anchorage for a shorter residual limb could potentially reduce these problems and lead to increased prosthetics wear and satisfaction. We believe that OI surgery could lead to functional independence for active military and Veterans who can’t otherwise tolerate a prosthesis. We aim to advance the science and technology supporting osseointegrated prostheses to the benefit of the wounded Warfighter.