Comparing simultaneous and staged bilateral total knee arthroplasty: a systematic review and meta-analysis

For patients with bilateral knee osteoarthritis, staged bilateral total knee arthroplasty (StaBTKA) is generally considered lower in perioperative risk, while simultaneous bilateral total knee arthroplasty (SimBTKA) enables one-stage deformity correction and potential earlier rehabilitation, with its safety debated. This study aimed to systematically compare their clinical outcomes using available observational evidence.

PubMed, Embase, the Cochrane Library, Ovid, and Web of Science were systematically searched for studies published between January 1, 2000 and August 31, 2025. Cohort studies comparing SimBTKA and StaBTKA were included, and all eligible studies were observational in design.

A total of 53 cohort studies involving 572,881 patients were included, comprising 244,207 patients in the SimBTKA group and 328,674 in the StaBTKA group. In studies reporting comparable short-term mortality windows, SimBTKA was associated with higher reported short-term mortality than StaBTKA (OR = 2.35, 95% CI 1.69-3.27, P < 0.001). SimBTKA was also associated with a higher incidence of deep vein thrombosis (OR = 1.45, 95% CI 1.37-1.53; P < 0.001) and greater transfusion requirements (OR = 4.42, 95% CI 3.11-6.28; P < 0.001). Length of stay tended to be shorter with SimBTKA, particularly in Asian studies; however, substantial heterogeneity limited the interpretability of a precise pooled estimate. In contrast, StaBTKA was associated with higher rates of superficial and deep infection (OR = 0.69, 95% CI 0.54-0.89; P = 0.004; OR = 0.65, 95% CI 0.61-0.70; P < 0.001). No significant differences were observed between the two strategies in revision rates, pulmonary embolism, neurological complications, or cardiac events.

SimBTKA and StaBTKA have distinct risk profiles rather than one being universally superior. SimBTKA was linked to higher reported short-term mortality, DVT, and transfusion, whereas StaBTKA was associated with higher infection rates. The mortality finding should be interpreted cautiously because survivor selection bias may underestimate true risk in the StaBTKA group. Surgical strategy should be individualized, balancing patient comorbidities, perioperative safety, treatment efficiency, and healthcare resource utilization.