Osseointegrated Prosthetic Implants for People With Lower-Limb Amputation: A Health Technology Assessment

Abstract

Background

Osseointegrated prosthetic implants are biocompatible metal devices that are inserted into the residual bone to integrate with the bone and attach to the external prosthesis, eliminating the need for socket prostheses and the problems that may accompany their use. We conducted a health technology assessment of osseointegrated prosthetic implants, compared with conventional socket prostheses, for people with lower-limb amputation who experience chronic problems with their prosthetic socket, leading to prosthesis intolerance and reduced mobility. Our analysis included an evaluation of effectiveness, safety, cost-effectiveness, the budget impact of publicly funding osseointegrated prosthetic implants, and patient preferences and values.

Methods

We performed a systematic literature search of the clinical evidence on the safety and effectiveness of the latest iterations of three implant systems: the Osseointegrated Prostheses for the Rehabilitation of Amputees (OPRA) Implant System, the Endo-Exo-Femur-Prosthesis, and the Osseointegration Group of Australia–Osseointegration Prosthetic Limb (OGAP-OPL). We assessed the risk of bias of individual studies and determined the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic economic literature search and conducted a cost–utility analysis with a lifetime horizon from a public payer perspective. We also analyzed the net budget impact of publicly funding osseointegrated prosthetic implants in Ontario. To contextualize the potential value of osseointegrated prosthetic implants, we spoke with people with lower-limb amputations.

Results

We included nine studies in the clinical evidence review. All studies included patients with above-the-knee amputation who underwent two-stage surgery and mostly had short-term follow-up. With osseointegrated prosthetic implants, scores for functional outcomes improved significantly as measured by 6-Minute Walk Test (6MWT), Timed Up and Go (TUG) test, and Questionnaire for Persons with a Transfemoral Amputation (Q-TFA). The scores for quality of life measured by SF-36 showed significant improvement in the physical component summary but a nonsignificant decline for the mental component summary. The most frequently seen adverse event was superficial infection, occurring in about half of patients in some studies. Deep or bone infection was a serious adverse event, with variable rates among the studies depending on the length of follow-up. The treatment of deep or bone infection required long-term antibiotic use, surgical debridement, revision surgery, and implant extraction in some cases. Other adverse events included femoral bone fracture, implant breakage, issues with extramedullary parts that required replacement, and implant removal. Our assessment of the quality of the clinical evidence according to the GRADE criteria found low certainty in terms of improvement in functional outcomes, low certainty for quality of life, and high certainty of an increase in adverse events; all findings compared receiving an osseointegrated prosthetic implant with not receiving an osseointegrated prosthetic implant.

In our economic model, osseointegrated prosthetic implants were found to be more effective and more expensive than having people remain users of an uncomfortable socket prosthesis. Our best estimate of the incremental cost-effectiveness ratio (ICER) for osseointegration, compared with an uncomfortable socket, was $94,987 per quality-adjusted life-year (QALY) gained. The probability of osseointegration being cost-effective was 54.2% at a willingness-to-pay value of $100,000 per QALY gained. The annual net budget impact of publicly funding osseointegrated prosthetic implants in Ontario over the next 5 years, for a small population of eligible candidates, would range from $1.5 million in year 1 to $0.6 million in year 5, for a 5-year total of $5.3 million.

We interviewed 13 people with a lower-limb amputation; nine had experience with both a conventional socket prosthesis and an osseointegrated prosthetic implant, three had experience with a conventional socket prosthesis only, and one had only recently undergone amputation and had not yet chosen a prosthesis. People who had received an osseointegrated prosthetic implant said they had better mobility and quality of life than before receiving this implant but had concerns about the ongoing risk of infection and potential for problems with implant maintenance. People using a conventional socket prosthesis said cost was the only factor preventing them from undergoing an osseointegration procedure.

Conclusions

In the studies included in the clinical evidence review, most people who received osseointegrated prosthetic implants were followed for only a few years. Studies showed that functional outcomes and physical ability improved with osseointegrated prosthetic implants (GRADE: Low), but there was uncertainty about the impact of these implants on people's emotional health (GRADE: Low). Osseointegrated prosthetic implants can lead to serious adverse events such as bone infection and bone fracture in some patients, which may require additional surgeries (GRADE: High). The reference case of the primary economic evaluation represented a conservative estimate of cost-effectiveness and found osseointegration may be cost-effective, but there is a large degree of uncertainty given parameter uncertainty and the need to use proxy costs. Scenario analyses explored potential variations in approaches to modelling and parameter selection. Qualitative interviews with people with a lower-limb amputation and caregivers underscored the challenges of conventional socket prostheses, but cost remains an important barrier to pursuing osseointegrated prosthetic implantation.