Functional outcome of conversion total hip arthroplasty (CTHA) using uncemented distally loading femoral stem for failed fixation of proximal femoral nail - A case series.

Introduction and aims: There is paucity of prospective studies on conversion total hip arthroplasty (CTHA) for failed proximal femoral nailing. The objective of this study is to evaluate the functional outcome of CTHA using extensively porous coated distal loading stem for failed proximal femoral nailing. Patients and methods: Fifteen consecutively operated patients for failed proximal femoral nail treated with single stage procedure of nail extraction and CTHA were included in this prospective observational study. All patients received metal-on-polyethylene bearing with uncemented press-fit acetabular cup (Pinnacle cup; DePuy, Warsaw [IN], USA) and extensively porous coated distally loading revision stem (Solution stem; DePuy, Warsaw [IN], USA). All patients were assessed preoperatively and postoperatively at one, three, six and more than twelve months using the Harris Hip Score (HHS). The responsiveness of HHS was assessed using Effect Size (ES) and Standardised Response Mean (SRM). ES and SRM >0.8 indicates adequate responsiveness. Results: The mean duration of follow-up was 16.9 months for the overall cohort (SD: 7.9; range: 6-28 months). The mean preoperative HHS was 32 ± 6.1, the mean HHS at six months follow-up was 89.7 ± 4.0 and the mean HHS at final follow-up of atleast one year was 93.7 ± 3.0. There was a statistically and clinically significant improvement in the HHS from preoperatively to final follow-up postoperatively (p < 0.0001). At the final follow-up, twelve patients (80%) had an excellent outcome and three patients (20%) had a good outcome as per HHS grading. The ES was 9.87 and the SRM was 8.86 thereby suggesting adequate responsiveness. One patient developed surgical site infection and another patient developed dislocation. Both were successfully treated and subsequently the patients made uneventful recovery. None of the patients required revision surgery. Conclusion: HHS has adequate responsiveness for assessing the functional outcome of CTHA. We recommend the use of an uncemented cup and uncemented extensively porous coated, distal loading stem for failed PFN fixation in intertrochanteric hip fractures.