Mortality and implant survival with simultaneous and staged bilateral total knee arthroplasty experience from the Australian Orthopaedic Association National Joint Replacement Registry

Background: Total knee arthroplasty (TKA) is an effective procedure for relieving pain and restoring function in osteoarthritis, with a significant proportion of patients having severe disease bilaterally. However, although there are differences in patient selection criteria for bilateral procedures, there is no consensus regarding the optimal timing for bilateral TKA. The aim of this study is to compare rates, causes of revision and 30-day mortality between simultaneous and staged bilateral TKA using data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Methods: Data for over 36,000 bilateral TKAs was collected from September, 1999 to December, 2015. Rates and causes of revision and 30-day mortality rate were obtained for simultaneous bilateral and staged procedures with intervals of 1 day–6weeks, 6weeks–3months and 3months–6months. Yearly cumulative percent revision (CPR) or survival (CPS) with 95% confidence intervals calculated by the Kaplan-Meier method and adjusted hazard ratios were used for comparisons. Results: There was no significant difference between revision rates or reasons for revision between staged bilateral and simultaneous TKA (HR 1.09 (95% CI 0.85-1.40; p=0.511) for 1day–6weeks, 0.93 (95% CI 0.77-1.14; p=0.494) for 6weeks–3months, and 1.10 (95% CI 0.98-1.23; p=0.115) for 3months–6months). The most common reasons for revision were loosening/lysis and infection. The 30-day mortality rates were lower in the 6weeks-3months group than simultaneous bilaterals (p=0.007). Conclusion: This study demonstrates that simultaneous and staged bilateral TKA have similar rates of revision over the medium term but that 30-day mortality is reduced in the 6weeks-3months group