Bilateral character of total hip replacement does not change the overall survival.

The purpose of this study was to compare the long-term survivorship of total hip replacement in unilaterally and bilaterally operated patients and try to answer the question whether analyses of combined unilateral and bilateral cases could result in erroneous interpretations. The material consisted of 266 Charnley's low-friction arthroplasties performed on 193 patients with osteoarthritis of the hip, followed for a minimum of 15 years. The 25-year survivorship of unilaterally operated hips was 69.2% (95% CI 57%-81.4%) and of bilaterally 66.4% (95% CI 57.6%-75.2%), respectively (p = 0.324). Cox regression analysis of unilateral and bilateral cases for confounding factors of gender, age and primary diagnosis confirmed that there was no significant relationship between survival of THR and whether the patient is unilaterally or bilaterally operated. Only age had a significant relationship with the survival of THR. In bilateral cases, Cox analysis for possible predictive factors found that the primary diagnosis, time interval between the two operations and sequence of the operation were not significantly correlated with the survivorship of bilateral THRs. We thus concluded that in analysing a combination of unilateral and bilateral cases, and presenting the long-term THR results, the bilateral character does not change the overall survival.