Comparison of Functional Outcomes Between the First and Second Knee in Staged Bilateral Total Knee Arthroplasty With Diverse Intervals Between Stages.

BACKGROUND: The objective of the study was to analyze if the length of interval time between stages influenced functional and quality of life outcomes in patients with staged bilateral primary total knee arthroplasty (TKA). METHODS: This is a retrospective comparative study between 93 patients with an interval between stages of 6-8 months (6-month group), 112 of 12-14 months (1-year group), and 108 of 24-26 months (2-year group). Outcome variables were Knee Society scores, Western Ontario and McMaster Universities, Short Form, and patient satisfaction. RESULTS: Overall, the mean follow-up for the first TKA was 8.2 (range, 7-10) years, and for the second TKA, 6.7 (range, 5-10) years. At last follow-up, functional and patient-related outcomes were similar for both knees, regardless of the interval. However, mental score and patient satisfaction were significantly better for the second than for the first TKA in the 2-year group. Age did not correlate significantly with the functional scores but was significantly correlated with the mental score. CONCLUSION: The performing staged bilateral TKA with a wide interval between surgeries provided equivalent functional outcomes and quality of life for both knees. Postoperative outcomes were not affected by the length of the time interval between procedures or age. Our results can help the surgeon to inform the patients reliably about what they can expect in the delay of a second knee replaced. Thus, patients could make an informed decision.