COPYRIGHT © 2003 BY THE JOURNAL OF BONE AND JOINT SURGERY, INCORPORATED Simultaneous Bilateral, Staged Bilateral, and Unilateral Total Knee Arthroplasty A SURVIVAL ANALYSIS

Background: The rates of perioperative morbidity and mortality are areas of concern associated with simultaneous bilateral total knee replacement. The purpose of this paper was to compare the rates of morbidity and mortality and the clinical outcome in large groups of consecutive patients undergoing simultaneous bilateral total knee replace-ment, unilateral total knee replacement, or staged bilateral total knee replacement. Methods: A total of 6200 total knee replacements, performed in 3998 patients between 1983 and 2000, consisted of 2050 simultaneous bilateral, 1796 unilateral, and 152 staged bilateral total knee replacements. A review of each group was conducted to compare the rates of morbidity and mortality, the survival of the prosthesis, and the clinical outcome. Kaplan-Meier survival analyses were performed with failure defined as revision because of aseptic loosen-ing and as patient death. Complications and Knee Society scores were compared throughout the fifteen-year follow-up period (average, 4.3 years of follow-up). Results: The unilateral group had significantly lower Knee Society scores than the simultaneous bilateral group (p < 0.0001 up to twelve years, and p = 0.0067 at fifteen years) across all postoperative time-intervals. The percentage of patients who had thrombophlebitis was significantly higher in the simultaneous bilateral group (0.9%) than in the unilat-eral group (0.3%) (p = 0.0326). No significant differences were found with regard to prosthetic failure, cardiac complica-tions, and the rates of death in the three groups. Ten years postoperatively, the simultaneous bilateral group had