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Similar outcomes found with simultaneous bilateral, unilateral and staged TKAs
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Simultaneous bilateral total knee arthroplasties are associated with an increased risk of clinical thromboembolism compared to unilateral and staged procedures. But, overall, the risk in morbidity and mortality associated with the simultaneous procedures is minimal compared with unilateral staged procedures.
“We believe that when adequate indications exist for bilateral total knee replacements (TKRs), simultaneous arthroplasties are beneficial to patients with minimal increase in the risk of death or complications as compared to unilateral and staged procedures,” Merrill A. Ritter, MD, told attendees at the Current Concepts in Joint Replacement — Winter 2003 Meeting.
Ritter’s review included 6200 TKAs performed on 3998 patients between 1983 and 2000. There were 4100 simultaneous bilateral, 1796 unilateral and 304 staged bilateral TKRs performed at an average interval of 1.4 years (range: 10 days to three years).
Ritter compared each group for morbidity, mortality, prosthesis survival and clinical outcome. He subjected each group to two Kaplan-Meier survival analyses, with failure defined as revision for aseptic loosening and patient death. Complications and Knee Society Scores were compared throughout a 15-year follow-up period (average follow-up: 4.3 years).
“The unilateral group had significantly lower Knee Society scores than the simultaneous bilateral group (P<.001) at three, five, seven, 10, 12 and 15 years,” Ritter reported. “No differences between the three groups were found with regard to cardiac complications.”
Increase in thromboembolism
The simultaneous bilateral group had a significantly higher percentage of clinical thromboembolism (0.9%) than the unilateral group (0.3%).
No significant differences were found with regard to prosthesis failure between the three groups, Ritter reported.
No significant differences were found between the death rates in the three groups at two weeks, three months or one-year postoperatively. Ten years postoperatively and beyond the simultaneous bilateral group had a significantly higher rate of patient survival than the unilateral group. The 10-year survival probability for the simultaneous bilateral group was 78.6% (95% CI, 75.0%-82.1%); for the unilateral group it was 72.0% (95% CI, 66.7%-77.2%).
Similar clinical outcomes
The simultaneous bilateral, unilateral and staged bilateral groups all had similar clinical outcomes with regard to Knee Society scores, although the scores were statistically lower in the unilateral group (P<.0001) across all postoperative time intervals.
“The significantly higher percentage of thromboembolism in the simultaneous bilateral group than in the unilateral group may represent a greater risk to patients undergoing the simultaneous bilateral procedure,” Ritter said.
Ritter found no significant differences with the numbers available with regard to prosthesis survival or with regard to patient death within the first nine postoperative years.
According to Ritter, candidates for simultaneous bilateral TKA have severe pain and deformity in both knees and are younger than 70 years of age. For patients older than 70, there is an increased risk of mortality.
Elderly patients and patients with multiple medical comorbidities are not candidates for simultaneous bilateral TKA, Ritter said.
For more information:
- Ritter MA. The efficacy of bilateral TKA: A turn of the tide. Presented at the Current Concepts in Joint Replacement — Winter 2003. Dec. 10-13, 2003. Orlando, Fla.
- Ritter MA, Harty LD, Davis KE, Meding JB, Berend M. Simultaneous bilateral, staged bilateral, and unilateral total knee arthroplasty: A survival analysis. JBJS (American). 85:2003;1532-1537.