Staged Bilateral Total Knee Arthroplasty: when should the Second Knee be Replaced?

Background: Bilateral total knee arthroplasty (BTKA) under the same anesthesia (simultaneous) or staged are options for patients with end-stage arthritis of the knee that carries advantages and limitations. Not all patients are candidates for simultaneous BTKA, and therefore, surgeons prefer to stage the two TKAs. The optimal safe interval between two TKAs is not known. The present systematic review aimed to determine the optimal time interval between the two stages of BTKA. Methods: Pubmed and Scopus databases were searched to identify publications from January ۱۹۷۹ to November ۲۰۱۷ in English that compared the outcomes of staged BTKA performed using various time intervals between the two TKAs. Data on systemic and local complications following staged BTKA were extracted, and the pooled data were analyzed to adjust for age. Results: In total, ۲۳ studies that enrolled ۱۱۷,۰۹۰ patients undergoing staged BTKA were included in this systematic review. A significant increase was observed in the incidence of myocardial infarction (OR=۸.۴ and ۸.۳۲), other cardiac complications (OR=۱۷.۷۱ and ۱۸.۱۸), deep vein thrombosis (OR=۴.۷۲ and ۴.۸۹), pneumonia (OR=۳.۳۷ and ۳.۴۵), and knee revision (OR=۳.۷۳ and ۴.۱۴) in patients undergoing the second TKA within ۳۰ days or ۹۰ days of the first TKA. However, the replacement of the second knee within this time interval was associated with a significantly lower risk of pulmonary embolism (OR=۰.۱۴۵ and ۰.۱۲۸), superficial (OR=۰.۱۴ and ۰.۷۹) and deep knee infection (OR=۰.۰ and ۰.۰), as well as vascular complications (OR=۰.۰ and ۰.۴۲). Conclusion: Time interval of less than ۳۰ or ۹۰ days between two TKAs performed in patients with BTKA was associated with a higher risk of systematic complications. However, the shorter time intervals between the two TKA may reduce the risk of other complications. This information may help surgeons' council patients better when deciding on the optimal time interval between two TKAs. Level of evidence: I