Polyethylene Exchange During Retrograde Intramedullary Nailing in the Treatment of Periprosthetic Distal Femur Fractures: A Registry Pilot Analysis.

INTRODUCTION: The primary purpose of this study was to report the indications for and the rate of polyethylene exchange (PE) during retrograde intramedullary nailing (rIMN) in periprosthetic distal femur fractures. This study also explores the role of polyethylene-related etiologies of patients experiencing prefracture TKA instability. METHODS: Retrospective review was done on patients older than 18 years treated with rIMN or nail-plate combination (NPC) for periprosthetic fracture (PPFx) of the femur above a total knee arthroplasty with well-fixed components from 2013 to 2023. Patient demographic, perioperative, and surgical data were collected. Descriptive data were reported as means ± standard deviation (SD) for continuous data or counts (%) for categorical data. RESULTS: Twenty-six patients met inclusion criteria and were included for analysis. Seven patients (26.9%) had reports of instability before fracture. Of these, 5 (71.4%) reported catching, 1 (14.2%) presented with antecedent pain, and 1 (14.2%) experienced giving out. The incidence of PE was 34.6% (9/26). Indications for exchange were flexion instability in 33.3% (3/26), damaged polyethylene in 22.2% (2/26), blocked nail entry in 22.2% (2/26), flexion instability with internal rotation deformity in 11.1% (2/26), and polyethylene wear in 11.1% (2/26). CONCLUSION: This pilot study demonstrates a higher incidence of PE than previously reported in the literature. Indications for PE in distal femur PPFx around a TKA in this cohort include postfixation flexion instability, intraoperative polyethylene damage, blocked nail entry, and polyethylene wear. With larger, prospective studies, an increased understanding of the role for PE may lead to improved patient outcomes and limit morbidity associated with recurrent and new TKA instability postoperatively.