Clinical Outcomes and Complications Following Hip Fusion Conversion to Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

Background: Efficacy, clinical outcomes, and complications following hip fusion conversion to total hip arthroplasty (THA) surgery have been explored in several studies with controversial findings and no consensus.Methods: Comprehensive search of online databases was performed through December 2022 for prepost clinical trials using MeSH keywords. Harris hip score (HHS), leg length discrepancy (LLD), pain score, and range of motion (ROM) were considered as clinical outcomes along with implant survival and complications. The retrieved studies were assessed for methodologic quality. Weighted mean difference (WMD) with 95% confidence interval (CI) were calculated using random effects meta-analysis taking into account for heterogeneity. Subgroup meta-analysis as well as sensitivity analysis were performed.Results: Findings of meta-analysis on 34 trials showed that HHS increase after THA (WMD: 42.3; 95% confidence interval (CI): 38 to 47). Subgroup analyses indicated that cementless prosthesis, length of arthrodesis <12 years, age <45 years, and studies with good quality have more HHS improvement. The LLD decreased 21 mm (95% CI: 19 to 24 mm) based on 21 trials. The range of motion (ROM) reached to 89 (95% CI: 84 to 95) for flexion, 32 (95% CI: 27 to 37) for abduction, 25 (95% CI: 21 to 29) for adduction, 29 (95% CI: 25 to 33) for external rotation, and 25 (95% CI: 20 to 31) for internal rotation after surgery. The most common complication was heterotopic ossification (14%).Conclusion: Conversion of an ankylosed hip to THA leads to improved hip function and leg discrepancy with relatively notable rate of complications. Our findings could provide a framework to guide surgeons and decision makers.