High Conversion Rate to Total Hip Arthroplasty after Hemiarthroplasty in Young Patients: Single-center, Retrospective Comparative Cohort Study with a Minimum Follow-up of 10 Years

Background: This study aimed to evaluate the long-term results of bipolar hemiarthroplasty (BHA) in patients aged < 60 years and to analyze the risk factors for acetabular erosion after BHA. Methods: This retrospective study included 114 patients who underwent BHA were followed-up for at least 10 years. The mean age was 54.1 years, and the mean follow-up duration was 13.8 years. The patients were divided into two groups according to the presence of acetabular erosion, and the preoperative parameters were compared between the two groups. Moreover, the risk factors related to acetabular erosion after BHA were analyzed using statistical comparisons.Results: Reoperation was performed in 44 of the 114 patients (38.6%). The survival rate when the end point was reoperation related to acetabular erosion was found to be significantly time-dependent: 73.2% at 5 years, 48.8% at 10 years, and 25.9% at 15 years. The acetabular erosion group showed significantly younger age at the time of surgery, higher body mass index (BMI), more avascular necrosis of the femoral head, and smaller prosthetic femoral head. The final multivariate logistic regression analysis showed that young age at the time of surgery were independent risk factors for acetabular erosion after BHA in patients aged < 60 years.Conclusion: The minimum 10-year follow-up outcomes of BHA in patients aged < 60 years showed a relatively high conversion rate to total hip arthroplasty. When considering BHA in younger patients, more careful decisions should be made with respect to patient’s choice, keeping in mind that long-term survival cannot be guaranteed.