Bilateral Simultaneous Total Knee Arthroplasty: A Patient-Matched Retrospective Observational Study.

Bilateral total knee arthroplasty can be performed either as a staged or simultaneous procedure. We conducted a retrospective comparative study to compare the need for transfusion, the length of procedure, the length of stay, and complications of bilateral simultaneous knee arthroplasty with those of unilateral knee arthroplasty. Sixty-nine patients who underwent bilateral simultaneous knee arthroplasty procedures were compared with a matched control group of 69 patients who underwent unilateral knee arthroplasty. Receiver Operating Characteristic (ROC) curve was used to determine optimum cut-off values. Both groups of patients had a similar age and gender distribution, preoperative haemoglobin and ASA scores. Cumulative transfusion episodes were lower in the bilateral group than twice that of the unilateral group. In multivariate analysis the preoperative haemoglobin level and bilateral procedures were independent factors predicting the need for transfusion. The average length of procedure and length of hospital stay in the bilateral group was less than twice than that of the unilateral group. Advanced age and bilateral procedures were independent predictors of prolonged length of stay. A haemoglobin level of 12.5 g/dL and age of 70 were most suitable cut-off points to predict need for transfusion and occurrence of medical complications respectively. We conclude that bilateral simultaneous knee arthroplasties are safe and cost effective in appropriately selected patients. We recommend avoiding bilateral simultaneous procedures in patients over the age of 70 years and with significant comorbidities.