A Solution to Poorly Tolerated Lower Limb Amputations: Osseointegrated Prostheses Prove Cost-effective in the United States

Abstract

PURPOSE: This study is the first cost–benefit analysis of osseointegrated implant (OI) prostheses compared with socket-suspended (SS) prostheses for lower limb amputees in the United States. The use of traditional SS prostheses for patients with transfemoral and transtibial amputations can be complicated by issues like poor fit, tissue damage, and pain at the socket-limb interface. These complications often require management by plastic surgeons. Osseointegration provides an alternative solution by anchoring the prosthesis directly to an implant in the user’s residual limb; this procedure involves both orthopedic and plastic surgery teams. The operation, materials, and maintenance associated with osseointegration can be expensive, but patient-reported data suggest that OI leads to better quality of life in patients who are dissatisfied with their SS prosthesis. METHODS: We used a Monte Carlo model to project costs and lifetime quality-adjusted life years (QALYs) for patients with OI and SS prostheses. Simulation parameters for the base-case scenario were derived from a cohort of 25 patients who underwent osseointegrated implantation following unilateral lower limb amputations at our institution between October 2017 and February 2020. An IRB-approved retrospective chart review was performed on each patient. CPT codes, material costs, length of surgery, and length of inpatient stay were collected for all encounters related to the amputation site. Utilities and SS prosthesis costs were derived from the literature. We calculated and compared incremental cost-effectiveness ratios (ICERs) for OI and SS prostheses. Parameters were varied individually in one-way sensitivity analyses to evaluate the sensitivity of the results to plausible variations in model inputs. RESULTS: Our patients had an average age of 49.6 years at implantation and were followed for 17 months on overage. In total, 84% of patients had traumatic amputations. We found the average cost of osseointegration surgery to be $54,503. An estimated 20% of patients required a pre-implantation residual limb revision surgery, averaging $49,191. Maintenance of a healthy OI prosthesis cost on average $2626 per year. Complication rates per year and average costs were as follows: soft tissue infection (29%, $435), bone/implant infection (11%, $11,721), painful neuroma (14%, $14,659), and mechanical failure (17%, $46,513). In the base-case scenario, the ICER of OI prostheses compared with SS prostheses was $44,660. A cost effectiveness acceptability curve showed that OI was favored over SS in 71% of cases at a willingness-to-pay of $50,000 per QALY. In one-way sensitivity analyses, the ICER was most sensitive to the mechanical failure rate, mechanical failure cost, and alternative yearly SS prosthesis cost. CONCLUSIONS: Our model suggests that osseointegrated implantation can provide a higher quality of life at affordable costs when compared with poorly tolerated SS prostheses in patients with lower limb amputations in the United States. Intraoperative reconstruction and postoperative management by a plastic surgeon is essential to minimize complications and thus improve cost-effectiveness and patient satisfaction. More follow-up must be done to understand the long-term benefits and risks of OI-based prostheses.