What Functional Outcomes Can Be Expected With Osseointegrated Prostheses in Transfemoral Amputations?

Abstract

Background: Individuals who have undergone transfemoral amputation often have difficulty donning and utilizing a conventional socket prosthesis. Osseointegrated prostheses may alleviate certain issues, potentially resulting in better outcomes, but few prospective studies have either evaluated these outcomes or quantified the purported benefits.

Questions/purposes: (1) Did patient-reported outcome measures improve between baseline and 2-year follow-up among those who underwent osseointegration surgery after transfemoral amputation? (2) What was the frequency and severity of early complications related to the osseointegration procedures? (3) What was the minimum clinically important difference (MCID) in a global patient-reported outcome measure in this patient population?

Methods: Between October 2017 and October 2023, we recruited 41 participants to undergo transfemoral osseointegration surgery treated with the Osseointegrated Prostheses for the Rehabilitation of Amputees implant system for patients who had trouble utilizing traditional, socket-based prostheses. Of those, 5% (2 of 41) did not undergo surgery, 2% (1 of 41) were lost to follow-up, and 2% (1 of 41) died before the final 2-year follow-up, leaving 90% (37 of 41) for analysis in this prospective, observational trial. Participants were asked to complete the validated Questionnaire for Persons with a Transfemoral Amputation (Q-TFA) and the Patient-Reported Outcomes Measurement Information System (PROMIS) questionnaire before surgery as well as 3, 6, 12, and 24 months after the two-stage procedure. Thirty-seven participants (three women and 34 men; mean ± SD age 38 ± 10 years) reached the 24-month follow-up visit, and four patients were withdrawn. We tabulated the frequency and types of surgical complications that patients experienced and calculated the anchored-based MCID for the Q-TFA global score (0 to 100 maximum). The Q-TFA's global score is generated based on answers to three questions: "How would you summarize your level of function with your current prosthesis?", "How would you summarize the problems you experience with your current prosthesis?", and "How would you summarize your overall situation as an amputee?" Using the sum of the numerical scores for the three questions, we found the difference between the baseline and the final follow-up for the participants. Then, we took the first quartile of the difference to represent the median change in the lower 25% of the data and used this value as our MCID.

Results: Scores in the study group improved in nearly all domains of the Q-TFA and PROMIS, including those related to prosthetic use, prosthetic mobility, and physical function (all p < 0.05). Patients developed superficial infections in 29% (15 of 51) of implanted limbs, all of which were treated successfully with antibiotics alone; 7 patients developed deep infections, only 1 of which involved the bone and implant. The anchor-based MCID in the Q-TFA global score was calculated as 17 of 100 for this study population.

Conclusion: Functional patient-reported outcomes improved in multiple domains among our patient cohort who underwent osseointegration surgery after transfemoral amputation, demonstrating the promise of this technology for patients with unsatisfactory function using conventional, socket-based prostheses. Infections and other complications were lower than in prior studies of osseointegration following limb loss. The novel MCID that we report can be used to determine whether patients have clinically important improvement in future osseointegration surgery studies comparing results between different implants, surgical techniques, and patient populations.

Level of evidence: Level II, therapeutic study.