What Are the Complications, Functional Outcomes, and Health-related Quality of Life of Bone-anchored Prostheses in Transfemoral Amputees? A Comparison of Single- and Two-stage Surgery Over Time

Background The insertion of an osseointegration implant providing direct skeletal attachment to an external prosthesis, creating a bone-anchored prosthesis (BAP), is an alternative for patients who have a lower limb socket-suspended prosthesis with socket-related problems. Historically, the osseointegrated implant was inserted in a two-stage procedure for safety reasons; however, the single-stage procedure is being performed and reported on as well. Because there are no studies comparing these two treatment strategies, we conducted this study to investigate complication rates, functional outcomes, and health-related quality of life (HRQoL). Questions/purposes Did patients who underwent single-stage surgery, compared with two-stage surgery, (1) have a lower frequency of adverse events, (2) have faster rehabilitation times and fewer sessions needed for completing the rehabilitation program, (3) perform better on the Timed Up and Go (TUG) test and 6-Minute Walk Test (6MWT), and (4) have superior HRQoL and prosthesis wearing time? Methods Between May 2009 and October 2019, Radboud UMC treated 238 patients with BAP, and between September 2017 and December 2019 treated 180 patients, of which 34% (62) had transfemoral amputation and an indication for the standard BAP in a two-stage surgery. Erasmus MC treated 57 patients, of which 51% (29) had transfemoral amputation and an indication for the standard BAP in a single-stage surgery. All patients were considered potentially eligible if they could provide written informed consent. Based on that, all patients were eligible, and of those from Radboud UMC, all were included; a further 3% (2 of 62) were lost at 2-year follow-up because of emigration. For patients from Erasmus MC, a further 10% (3 of 29) were excluded because 7% (2 of 29) did not provide informed consent and 3% (1 of 29) died of nontreatment-related causes. A total of 88 patients remained, with 86 patients remaining at 2-year follow-up. We performed a double-center, retrospective study of patients ages 18 years and older with 2 years of follow-up who were fitted with unilateral osseointegrated implants for a BAP through either single-stage (Erasmus MC, Rotterdam) or two-stage (Radboud UMC, Nijmegen) surgery between December 2014 and November 2019. Both hospitals are Level 1 trauma centers in The Netherlands. Surgeons at Radboud UMC began performing two-stage surgery in 2009 and eventually transitioned to single-stage surgery. Erasmus MC started in 2017 with BAP and exclusively performed single-stage surgery. Patients were eligible for osseointegrated implant surgery if they had demonstrated failure of previous treatments with socket prostheses. The respective clinical teams at each center conducted baseline assessments and postoperative follow-up at 6 months, 1 year, and 2 years as part of routine clinical care, independent of this study. The only differences in patient characteristics were that patients in the two-stage group were younger (mean ± SD 57 ± 13 years versus 64 ± 23 years), and that trauma as a cause of primary amputation occurred relatively more often in the single-stage group (62% [16 of 26]) compared with the two-stage group (45% [28 of 62]). The primary study outcome was the frequency of adverse events per surgical procedure within the fixed 2-year follow-up period. Secondary outcomes included rehabilitation characteristics, functional outcomes (TUG and 6MWT scores), and patient-reported outcomes (HRQoL and prosthesis wearing time). Independent t-tests, chi-square tests, Wilcoxon signed-rank tests, and Mann-Whitney U tests were used to assess differences between and within the two cohorts and study outcomes, with multiple testing corrections applied. Results A total of six infectious events were reported in 19% (5 of 26) of patients in the single-stage group compared with 22 events in 31% (19 of 62) of patients in the two-stage group. However, patients in the single-stage group experienced more major infection events. The frequency of surgical site infections was 6% (4 of 62) in the two-stage group versus 8% (2 of 26) in the single-stage group. Infections between Stage 1 and Stage 2 occurred in 27% (17 of 62) of patients in the two-stage group. There were no differences in rehabilitation duration (single-stage 15 ± 3 weeks versus two-stage 17 ± 16 weeks, mean difference 2 weeks [95% confidence interval (95% CI) -8 to 4]; p = 0.52); however, patients in the single-stage group had more sessions (22 ± 2 versus 18 ± 9 sessions, mean difference 4 [95% CI 1 to 7]; p = 0.02). Preoperatively, the single-stage group had worse median (IQR) TUG scores (12.8 seconds [11.0 to 16.8]) compared with the two-stage group (10.1 seconds [7.8 to 13.4], mean difference -3 [95% CI -7 to 1]; p = 0.007). Similarly, patients in the single-stage group had worse median (IQR) preoperative 6MWT scores (239 meters [160 to 290]) compared with the two-stage group (290 meters [220 to 367], mean difference 58 [95% CI 8 to 106]; p = 0.007). The TUG test showed greater median changes from baseline to 1-year and baseline to 2-year follow-up in the single-stage group (-3 versus -0.7; p = 0.003 and -3.5 versus -0.8; p < 0.001, respectively). Results were similar for the 6MWT (89 versus 29; p < 0.003 and 132 versus 38; p < 0.001, respectively). The median (IQR) Q-TFA global score was higher in the single-stage group at 2-year follow-up (75 [63 to 83]) compared with the two-stage group (67 [50 to 75], mean difference -8 [95% CI -18 to 2]; p < 0.001). All functional outcomes, except the TUG score at 6 months in the two-stage group, improved compared to baseline. Median changes of TUG and 6MWT scores between baseline and 1- and 2-year follow-up were better in the single-stage group. Conclusion The single-stage BAP procedure appears to offer possible benefits in terms of the frequency of minor adverse events, no need for second surgery, as well as possible faster and better improvement of functional outcomes over the two-stage approach. However, the frequency of major adverse events in the single-stage group should not be trivialized. Despite this, the single-stage procedure could become the preferred method for BAPs. Prospective, multicenter studies with larger cohorts could provide more robust, evidence-based insights into which procedure is more beneficial for future patients and whether major adverse events remain a possible concern. Level of Evidence Level III, therapeutic study.