Performance-Based Functional Outcomes Twelve and Twenty-Four Months after Transfemoral Osseointegration in Service Members with Traumatic Unilateral and Bilateral Lower Limb Loss.

Abstract

Objective: To evaluate functional outcomes at 12-months and 24-months after transfemoral osseointegration (OI), using established performance-based assessments DESIGN: Pre-post observational, single cohort SETTING: Military treatment facility PARTICIPANTS: Forty-seven service members (age=38±9y) with traumatic unilateral (n=22) and bilateral (n=25) lower limb loss. Before OI, n=2 unilateral and n=7 bilateral were not ambulatory on full-length prostheses.

Intervention: Transfemoral OI (two-stage threaded implant) MAIN OUTCOME MEASURES: Six-Minute Walk Test (6MWT), Timed Up and Go (TUG), Four Square Step Test (4SST), [Bilateral] Amputee Mobility Predictor ([B]AMP), Comprehensive High-level Activity Mobility Predictor (CHAMP).

Results: For both unilateral and bilateral cohorts, median performance-based functional outcomes were similar at 12-months and 24-months after vs. before OI: 6MWT (373 and 385 vs. 417m; p>0.31), TUG (9.7 and 9.6 vs. 9.8s; p>0.53), 4SST (9.5 and 10.6 vs. 10.8s; p>0.11), and CHAMP (12.6 and 10.6 vs. 12.3; p>0.44). Median BAMP scores were greater at 12-months (p=0.029) and 24-months (p=0.014) after vs. before OI among the bilateral cohort (30 and 35 vs. 16); median AMP scores were similar (p>0.10) among the unilateral cohort across timepoints (39 and 43 vs. 40). Among the 9 participants not ambulating with full-length prostheses before OI, 8 became capable of ambulation on full-length prostheses after by 24-months after OI.

Conclusions: While a lack of improvement in these particular outcomes is not exclusively suboptimal, particularly considering median scores at baseline reported here generally exceed other cohorts (both before and sometimes even after OI), these findings contrast with previous self-reported improvements in function after OI among service members with traumatic lower limb loss. As such, these data seemingly emphasize the importance of a comprehensive approach with both subjective and objective (multidisciplinary) outcomes for more fully characterizing OI, particularly within unique patient populations like young service members with traumatic lower limb loss.