CONVERSION TOTAL HIP ARTHROPLASTY FOLLOWING FAILED OSTEOSYNTHESIS OF PROXIMAL FEMORAL FRACTURES: A PROPENSITY-MATCHED CONTROLLED STUDY

Background Conversion total hip arthroplasty (cTHA) after failed hip fracture osteosynthesis is technically demanding and associated with higher complication rates than primary THA (pTHA). This study compares clinical and radiographic outcomes, between cTHA after failed proximal femoral fracture fixation and pTHA for osteoarthritis. Methods From institutional registry, 63 patients undergoing cTHA after failed osteosynthesis of AO/OTA type 31A (pertrochanteric) and 31B (femoral neck) fractures were identified and propensity-matched 1:2 with 126 pTHA patients. Baseline characteristics, operative and radiographic data, complication rates, and patient-reported outcomes (PROs) were evaluated up to five years postoperatively. Results In 63 cTHA patients, causes of failure included mal-/nonunion (38%) and symptomatic osteoarthritis (32%). Compared to pTHA, cTHA had longer surgical time (119 vs. 72 min; p < 0.001) and higher blood loss (383 vs. 315 mL; p = 0.065), with similar implant positioning. Heterotopic ossification was more common after cTHA. Revision surgery was performed in 3/63 cTHA patients (2 for periprosthetic infection, 1 for greater trochanter fracture). 1/128 pTHA was revised for implant malpositioning. Early PROs (6–24 months) were worse for hip function, activity, pain, and quality of life after cTHA; however, no significant differences persisted at five years. Fracture type did not influence PROs. Conclusion cTHA is more complex than pTHA, with longer surgical times and higher local complication rates. These factors should be reflected in reimbursement models. Mid-term 2-year cTHA PROs were worse but comparable at 5 years, indicating that conversion procedures can yield satisfying long-term clinical outcomes, particularly after femoral neck fractures. Philipp Neidenbach and Jakob Hax contributed equally to this study.