Simultaneous (two-surgeon) versus staged bilateral knee arthroplasty: an observational study of intraoperative and post-operative outcomes

Background: The advantages of simultaneous bilateral total knee arthroplasty (sim-BTKA) remain controversial. This study investigated the effects of two-surgeon sim-BTKA compared to separate admission staged BTKA regarding intraoperative and post-operative outcomes and health service costs. Methods: Patients underwent sim-BTKA or staged BTKA between 1 November 2008 and 30 June 2016. Data were extracted from a joint replacement registry and medical records. Median regression and chi-squared tests were used for between-group comparisons. Results: Median hospital total length of stay was 5 days less for sim-BTKA (n = 122) than staged BTKA group (n = 46) (7 versus 12; 95% confidence interval (CI) 3.9, 6.1), and 9 days less for inpatient rehabilitation (17 versus 26; 95% CI 3.7, 14.3). However, 80% of sim-BTKA patients went to inpatient rehabilitation (versus 27% following staged BTKA), so median total length of stay was 9 days less for staged BTKA (13 versus 22; 95% CI -12.8, -5.2). Total anaesthesia time was 135 min less for sim-BTKA (P < 0.001), while staged BTKA required less blood transfusions (P = 0.001). Complication rates were similar, except for superficial infections which were observed twice as often after staged BTKA (30% versus 15%, P = 0.048). Twelve months following sim-BTKA and the first staged total knee arthroplasty, sim-BTKA had better WOMAC pain, stiffness and function scores (P <= 0.05). Average inpatient costs (hospital and rehabilitation) were $6388 less for sim-BTKA. Conclusion: Sim-BTKA appears to be a comparatively safe alternative to staged BTKA. Sim-BTKA may be superior to staged BTKA due to faster improvements in pain and function and lower healthcare costs. How these results generalize to other health services requires further investigation.