In previous studies, simultaneous bilateral total knee arthroplasty (TKA) in appropriately selected patients has compared favorably with staged bilateral TKA—in terms of both clinical outcomes and cost. In the December 20, 2017 issue of The Journal of Bone & Joint Surgery, Meehan et al. report on a population-based analysis of 90-day and 180-day postoperative knee stiffness requiring manipulation under anesthesia (MUA) in three patient subgroups: those undergoing simultaneous bilateral, unilateral, and staged bilateral TKA. In this retrospective Level-III study, the authors made appropriate methodological adjustments to account for patients who planned a staged bilateral TKA but did not have the second operation.
In terms of cumulative MUA incidence after 90 and 180 days, rates were lowest in the simultaneous bilateral TKA group. After adjusting for relevant risk factors, Meehan et al. found that, after 90 days, the odds ratio (OR) of undergoing MUA after simultaneous bilateral TKA was significantly lower than that for unilateral TKA and staged bilateral TKA. Similar MUA odds were found among the three groups at 180 days.
The authors also identified significant nonsurgical risk factors for MUA at 90 days. Those included younger age, black race, no chronic comorbidities, and normal weight. The 180-day nonsurgical risk factors for MUA were the same as those for 90 days, with two additions—female sex and Hispanic ethnicity.
While Meehan et al. acknowledge that “there is no uniformity to indications for MUA” and that such decisions are “obviously surgeon- and patient-specific,” they nevertheless conclude that patients undergoing simultaneous bilateral TKA had a significantly lower risk of requiring MUA for stiffness than those in the other two TKA groups studied.