Outcome of hemiarthroplasty to total hip arthroplasty conversion: a systematic review.

Purpose: A systematic review of the literature was performed in order to synthesize the available data on the outcome of conversion total hip arthroplasty after failed hemiarthroplasty keeping in mind the higher complication rates of conversion as compared to a primary total hip arthroplasty.

Methods: Comprehensive search of literature was performed for the systematic review through online databases-PubMed, EMBASE, Scopus, and the Cochrane database. The abstracts were identified first by the above-mentioned search methods and were assessed for eligibility based on strict criteria. 15 studies regarding conversion hemiarthroplasty were finally included for the study.

Results: The 15 studies evaluating 3432 hips revealed that the main indication for conversion to arthroplasty was pain in the groin or thigh symptomatically and acetabular erosion with well-fixed femoral stem (455 cases; 13.25%) radiologically. Majority of the cases were revised in a single stage (292 cases) as compared to 25 cases revised in 2-stage surgery mostly owing to infection. The mean pre-conversion Harris Hip Score (HHS) improved from 45.74 to 84.03 in the post-conversion time. Majority of the conversions constituted cemented fixation for the femoral component and uncemented fixation for the acetabular component. Mean survivorship was found to be 97.21% at 5-6 years. The conversions were most commonly complicated by prosthetic joint infection most commonly which was managed by long-term antibiotics and/or debridement with or without exchange of implants.

Conclusion: The conversion group had consistently higher odds of prosthetic joint dislocation, prosthetic joint infection, periprosthetic fracture, aseptic loosening and revision both at 1- and 2-year follow-ups. It was also noteworthy that the odds of developing these complications increased significantly from 1-year follow-up to the 2 years follow-up.