Osseointegrated prostheses for the rehabilitation of patients with transfemoral amputations: A prospective ten-year cohort study of patient-reported outcomes and complications

Abstract

Background: Osseointegrated implants for patients with transfemoral amputations (TFAs) are a novel treatment under development, and prospective long-term evidence is lacking. The objectives were to determine patient-reported outcomes (PROs) and complications after ten years compared to before treatment and to compare the first five-year period with the later five-year period with regard to the outcomes.

Methods: In a nonrandomized, prospective cohort study, patients with TFAs treated between 1999 and 2007 with the Osseointegrated Prosthesis for the Rehabilitation of Amputees (OPRA) system (n ​= ​51) (28 men/23 women; mean age at amputation: 32 years old; mean age at treatment: 44 years old in a single university hospital were followed for ten years. PROs included the Questionnaire for Persons with a Transfemoral Amputation (Q-TFA, four scores 0-100) and the Short Form 36 Health Survey (SF-36, ten scores 0-100) and were answered before treatment and until the ten-year follow-up after treatment. Analyses of differences in PRO scores were conducted using Wilcoxon's signed rank test. The implant survival and revision-free rates with respect to adverse events (implant revision, mechanical complications, and deep infections) were presented as Kaplan-Meier graphs with 95% confidence intervals (CIs). The incidences of events per ten and five person-years were calculated. Spearman's correlation analysis was used for analyses of associations between adverse events.

Results: PROs showed statistically significant mean improvements between baseline and the ten-year follow-up with regard to all Q-TFA scores: the prosthetic use score (+36), prosthetic mobility score (+18), problem score (-28) and global score (+38) (all p ​< ​0.001), and the SF-36 physical functioning score (+26, p ​< ​0.001) and physical component score (+6, p ​< ​0.01). No PROs showed a statistically significant deterioration. Over the ten years, 12 patients were lost (one lost to follow-up, one dropped out of the study, two died, and eight had implants removed (four before five years and four between five and ten years). At ten years, the revision-free survival rates were 83% (CI: 69%-91%), 65% (CI: 49%-77%) and 17% (CI: 7%-29%) for implant revision, deep infection and mechanical complications, respectively. Mechanical complications, 3.9 per 10 person-years (CI: 2.2-5.1) constituted the most common serious adverse event and were more common during the last five years than during the first five years (p ​< ​0.001). No significant difference in the incidence of deep infections was observed between the earlier and the later five-year periods: 0.3 per 5 person-years (CI: 0.1-0.5) vs. 0.3 per person-years (CI: 0.1-0.5) (p ​= ​0.740). Correlation analyses between the earlier and later five years revealed a positive association between deep infections and implant removal (0.57, p ​< ​0.001) and between mechanical complications and adverse events (0.65, p ​< ​0.001).

Conclusion: Improved PROs were demonstrated ten years after the introduction of a novel principle for bone anchorage of amputation prostheses. Nevertheless, an increasing rate of mechanical complications is of concern.

Keywords: Adverse effects; Bone-anchored prosthesis; Osseointegration; Patient-reported outcome measures; Percutaneous; Quality of life.

Figure 1

Schematic of the location of the intramedullary fixture, abutment and abutment screw in the residual femur (A). Radiograph showing the location of the implant components in the femur (B). Photograph showing the residual limb and the macroscopic appearance of the percutaneous abutment with abutment screw (C). Photograph of a patient with a prosthesis attached to the osseointegrated implant in the femur (reproduced with permission and copyright © of The British Editorial Society of Bone & Joint Surgery [10]) (D). Flowchart and timeline description of the study cohort (E).

Figure 2

Questionnaire for Persons with Transfemoral Amputation (Q-TFA). The boxplots show the four Q-TFA scores at baseline and at five and ten years of follow-up (A, C, E, G) and the changes in the Q-TFA scores between baseline and five and ten years of follow-up (B, D, F, H). (A and B) Prosthetic Use score (0–100) (C and D) Prosthetic mobility score (0–100) (E and F) Problem score (100–0) (G and H) Global score (0–100). If the prosthetic use score is 0, the prosthetic mobility score, the problem score and the global score cannot be determined given a lower number of these three scores. The boxplots show the median (line), mean (plus), first and third quartiles (box), 5th and 95th percentile (whiskers) and the minimum and maximum data values. For comparisons over time (changes), Wilcoxon's signed rank test was used.

Figure 3

Q-TFA single question on the overall situation as an amputee, rated as extremely poor, poor, average, good or extremely good and answered at baseline and at the five- and ten-year follow-ups, regardless of prosthetic use.

Figure 4

Kaplan–Meier survival and revision-free rates. The graphs show the survival of the implant over time (A), the revision-free rates over time with respect to mechanical complications (B) and deep infections (C) and the overall serious adverse events (D).

Figure 5

Clinical complications. A. Bar graphs show the incidences of clinical adverse events per 10 person-years. B. Bar graphs show the incidences of adverse events per 5 person-years. Statistical comparisons in (B) were performed on the number of events of each category between the early (baseline-5 years) and late (5–10 years) periods. For comparisons, Wilcoxon's signed rank test was used. The error lines show the 95% CIs of the mean number of adverse events in each category. SI ​= ​superficial infections; DI ​= ​deep infections; MC ​= ​mechanical complications; STR ​= ​soft tissue revision; FR ​= ​fixture removal; AE ​= ​adverse events; SAE ​= ​serious adverse events.