(P 277) BEARING SELECTION IN PROXIMAL FEMORAL REPLACEMENT: A COMPARISON OF CLINICAL OUTCOMES

Objective: Proximal femoral replacement (PFR) involves extensive bone and soft tissue resection that increases the risk of overall instability. This can be addressed via implant bearing selection. Clinical studies comparing outcomes such as implant survival and time to dislocation with constrained liners, dual mobility, or bipolar implants are limited.

Methods: This retrospective study examined a single tertiary academic institution’s experience with PFR over a consecutive fifteen-year period. The indication was either revision arthroplasty after failed total hip arthroplasty (THA) or primary or metastatic tumor resection. Patients were stratified into one of 3 cohorts based bearing selection, which included bipolar, constrained liner, or dual mobility implants. Early dislocations were defined as a dislocation event within the first 3-months postoperatively.

Results: A total of 99 patients were identified who underwent PFR between 2005 and 2020. 42 underwent PFR with bipolar prosthesis (follow-up: 20.27 ± 22.48 months), 41 with constrained liner (follow-up: 40.73 ± 37.14 months), and 16 with dual mobility (follow-up: 19.65 ± 21.47 months). There were no differences in baseline patient demographics between groups. Dislocations occurred in 4 (9.5%) patients with a bipolar prosthesis, 8 (19.5%) with constrained liner, and 3 (18.8%) with dual mobility. Mean time to dislocation was 2.63 ± 2.49 months in the bipolar cohort, 1.87 ± 1.41 months in constrained liner cohort, and 10.68 ± 7.66 months in the dual mobility cohort (p=0.091). Kaplan-Meier survival analysis demonstrated a trend towards increased survival with dual mobility compared to traditional constructs (p=0.052).

Conclusion: Patients undergoing PFR for tumor resection and failed THA have similar overall dislocation rates regardless of the bearing. There is a trend towards the average time to dislocation being longer in dual mobility implants. Additional large-scale longitudinal studies with longer follow-up are needed to fully elucidate the differences in functional and survival outcomes.