Long-term outcomes of converting fused hips to total hip arthroplasty are satisfactory: a systematic review and meta-analysis.

Background: Although conversion arthroplasty of fused hips can relieve pain and provide patient satisfaction, long-term outcomes of total hip arthroplasty (THA) after hip fusion remain a subject of debate. This meta-analysis aimed to assess the effectiveness of THA for fused hips over a long period with concerns over potential complications. Methods: A systematic search of five databases from 2000 until 2023 identified English studies evaluating THA for fused hips with at least 100 months of follow-up. Meta-analyses were conducted using random-effect models via the comprehensive meta-analysis software. Sensitivity analysis, in-depth meta-regression, Egger's test, and the trim-and-fill method were performed appropriately. Results: The meta-analysis assessed 790 patients and 889 hips with a mean follow-up of 11 years. At the final follow-up, the mean Harris Hip Score (HHS) and leg length discrepancy (LLD) improved by 34.755 and 2.3 cm from the baseline, respectively. Regarding survival of hip fusion conversion to THA, most studies (88.8%) reported a 5-year implant survival rate of at least 90%, and the 15-year and 20-year implant survival rates, ranged between 80-90% and 70-90%, respectively. Subjective dissatisfaction with the conversion of hip fusion to THA was only 5.3%. Composite rates of revision, instability, and aseptic loosening were 13.6%, 3.8%, and 8.8%, respectively. Conclusions: Conversion of fused hips to THA results in favourable long-term outcomes regarding HHS, LLD, survival rates, and subjective satisfaction, leading to improved quality of life in properly selected patients. However, the presence of complications should be considered when evaluating the overall success of the procedure.