Effect of body mass index on range of motion and manipulation after total knee arthroplasty.

This study evaluates the effects of increased body mass index (BMI) on postoperative range of motion (ROM) and rate of manipulation under anesthesia (MUA) after total knee arthroplasty (TKA) in 391 primary TKAs. Range of motion and incidence of MUA were retrospectively collected and compared between 4 BMI groups (I, BMI <25; II, BMI 25-29.9; III, BMI 30-34.9; IV, BMI >35) using χ(2) or Fisher exact tests. Patients with higher BMIs had a greater incidence of MUA (I, 9.7%; II, 19%; III, 20%; IV, 15%) and lower preoperative and postoperative ROM. Women had lower ROM and a higher rate of MUA. Age was not a significant predictor of ROM or rate of MUA. Patients at greater risk of complications after TKA should be counseled about realistic surgical outcomes.