Percutaneous Osseointegrated Docking System for Above Elbow Amputees

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DESCRIPTION (provided by applicant): The overall goal of this three-year project is to maximize the functional recovery of patients with above elbow amputations (AEA) by developing an intramedullary Percutaneous Osseointegrated Docking System (PODS) that is ready for translation to human clinical trials. The design of the AEA PODS will address the challenges found in above elbow residual limbs of modern day warfighters (i.e. short residual limbs, heterotopic ossification (HO), shrapnel). Background: Socket-type attachment of an exoprosthesis to the residual limb is currently the standard of care, but is not suitable for all patients. Even patients successfully fitted with sockt-type attachments can be dissatisfied since they frequently experience pain from persistent deterioration of the soft tissues resulting from poor socket fit. In addition, blast related heterotopic ossification (HO) within the soft tissues of the residual limb cause further reductions in quality of life. It is for these kinds of patients that PODS devices are developed. There are three Specific Aims to this proposal. First, using morphological data from a pooled cadaver population with the diversity of personnel currently serving active duty for the United States, we will engineer a series of AEA PODS endoprostheses. We have a proven track record with this type of work not only with translational animal models, but also with human femurs for an upcoming FDA small feasibility clinical trial with AKA patients. In this project, we will deliver a series of AEA PODS sufficient to achieve a 95% confidence of fitting the pooled cadaver population. Second, we will verify the endoprosthetic fit of the AEA PODS using a sample population of de-identified VA and military patients with traumatic amputations. To date, PODS have not been designed to account for the unique clinical challenges found in both the VA and the military healthcare populations. Working directly with collaborators within the VA, the WRNMMC, and the BAMC healthcare systems, we will obtain de-identified CT image sets from trauma related AEA populations. By evaluating the designed AEA PODS using a sample patient population, we will be able to verify that the designs are adequate to preserve endoprosthetic fit of this unique population. We will deliver a series of AEA PODS sufficient to achieve a 95% confidence of fitting a sample patient population. Third, we will establish the initial post-operatve fixation expectations for AEA PODS. We believe that before rehabilitation of AEA PODS patients can safely be initiated, it is imperative to determine the relationship between the measured endoprosthetic fit of the AEA PODS endoprostheses and the expected post-operative fixation. We will deliver a mathematical relationship to estimate, within 95% confidence, the initial post-operative fixation of AEA PODS given the endoprosthetic fit. Study Design: Using our established protocols used to develop endoprosthesis for previous sheep animal models and upcoming FDA Feasibility trials for AKA PODS devices, we will engineer a series of AEA PODS sufficient to achieve a 95% confidence of fitting a sample AEA patient population and develop a mathematical relationship to estimate, within 95% confidence, the initial post-operative fixation of AEA PODS given the endoprosthetic fit. Relevance: In the development of PODS devices, patients with traumatic amputations above the elbow are currently underserved. As of 02 July 2012, the number of patients from OIF/OEF with major limb amputations has reached 1,506, of which 263 (17%) suffer from upper extremity involvement. Nationally, it is estimated in 2005, of the 1.5 million persons living with limb loss in 2005, 541,000 (36%) have an upper extremity involvement. Unfortunately, rejection of socket-type exoprosthetics is especially prevalent in AEA patients. Nearly 60% of AEA patients reject the use of their socket-based exoprosthesis because of issues such as poor fit, difficulties with training, limited usefulness, and short residual limb-length.