Mortality and Implant Survival With Simultaneous and Staged Bilateral Total Hip Arthroplasty: Experience From the Australian Orthopedic Association National Joint Replacement Registry.

Background: Total hip arthroplasty (THA) is an effective procedure for relieving pain and restoring function in osteoarthritis. A significant proportion of patients have severe disease bilaterally. Consensus regarding safety and selection of patients for simultaneous bilateral THA or the optimal timing for staged THA has not been reached. The aim of this study is to compare rates, causes of revision, and 30-day mortality between simultaneous and staged bilateral THA using data from the Australian Orthopedic National Joint Replacement Registry.

Methods: Data for 12,359 bilateral THA procedures were collected from September, 1999 to December, 2017. Rates and causes of revision and 30-day mortality were obtained for simultaneous bilateral and staged procedures with intervals of 1 day-6 weeks, 6 weeks-3 months, and 3 months-6 months. Yearly cumulative percent revision or cumulative percent survival with 95% confidence intervals calculated by the Kaplan-Meier method, and adjusted hazard ratios were used for comparisons.

Results: Thirty-day mortality is lower in patients who have bilateral procedures within 6 months, regardless of timing, than those who have unilateral procedures (0.06% vs 0.18%). Staged bilateral THA had a significantly lower mortality than simultaneous bilateral THA (odds ratio 0.175, 95% confidence interval = 0.04-0.78, P = .022). When separate time intervals were compared, no significant differences were seen. Bilateral 6 week-3 months has a higher rate of revision from 1.5 years-2years compared with same day bilaterals (hazard ratio = 2.39, 95% confidence interval = 1.12, 5.09, P = .024). There were no other significant differences in the rate of revision between groups. The most common reasons for revision were fracture, loosening, and infection. Simultaneous bilateral procedures have a significantly higher rate of revision for fracture compared with staging 3-6 months (hazard ratio = 1.96 [1.27, 3.03], P = .002).

Conclusion: This study demonstrates that bilateral THA has a low mortality rate regardless of time interval between procedures. Simultaneous and staged bilateral THA have similar rates of revision.