Results of Low Distal Femur Periprosthetic Fractures

Abstract

Objectives- To compare retrograde intramedullary nail (RIMN) and open reduction internal fixation (ORIF) in very distal periprosthetic distal femur fractures (PDFF) to determine if RIMN is an acceptable option for these fractures that are often considered too distal for IMN due to limited bone stock. Design- Retrospective comparative series Setting- Level One trauma center Patients- Patients treated with fracture fixation for a very distal PDFF, defined as the fracture extending to the anterior flange of the implant or distal. Fifty-six patients met inclusion criteria, with eight excluded for less than twelve months of follow-up. Intervention- Fracture fixation with RIMN or ORIF Main Outcome Measurements- The primary outcome was unplanned return to surgery. Secondary outcomes included fracture union, radiographic alignment, Visual Analog Score (VAS) and Patient-Reported Outcome Measurement Information System (PROMIS) Physical Function (PF) and Pain Interference (PI). Results- Mean follow up was 27 months. Twelve patients were treated with ORIF and 36 with RIMN. Twenty-one fractures were at the flange and 27 extended distal to the flange. There were no differences between fixation methods with respect to reoperation, deep infection, nonunion, malunion, VAS pain score, and PROMIS PI score. Mean PROMIS PF score was higher in the RIMN group compared to ORIF. There were five reoperations in the RIMN group (14%) and three in the ORIF group (25%). Conclusion- This is the largest series, to our knowledge, of a subset of very distal PDFFs. The results suggest that RIMN may be an acceptable treatment option for these very difficult fractures.