Conversion of a Failed Hip Hemiarthroplasty to Total Hip Arthroplasty: A Systematic Review and Meta-Analysis.

Background: Hip hemiarthroplasty (HA) and total hip arthroplasty (THA) are common treatments for femoral neck fractures in elderly patients. Despite HA's advantages of shorter operative times, less blood loss, and lower initial costs compared to primary THA, it may lead to conversion THA (cTHA). Our objectives are to evaluate the impact of conversion from HA to THA on Harris hip scores (HHS), compare complication rates between cTHA, revision THA, and primary THA, and assess the rates and types of complications following cTHA. Methods: A systematic review and meta-analysis were performed, evaluating studies published until 2023, with inclusion criteria entailing studies that explored outcomes and complications following cTHA of failed HA. Data extraction focused on variables such as postoperative HHS and complication rates, including periprosthetic joint infection, periprosthetic fracture, dislocation, stem loosening, acetabular loosening, and overall revision. Results: This study included 28 retrospective studies (4699 hips), showing a mean increase in HHS by 39.1 points, indicating a significant improvement from preoperative levels. Complication rates were detailed, with a 6.4% rate of periprosthetic joint infection, 2.2% for periprosthetic fracture, 7.6% dislocation, 1.6% stem loosening, 1.9% acetabular loosening, and an overall re-revision rate of 8.7%. Conclusions: Conversion from HA to THA generally results in improved functional outcomes, as evidenced by HHS improvements. Despite the positive impact on HHS, cTHAs are associated with notable risks of complications and the need for further revision surgeries. Level of Evidence: IV.