Knee stiffness requiring manipulation under anesthesia (MUA) is an undesirable outcome following total knee arthroplasty (TKA), but risk factors for, and optimal timing of, MUA remain unclear.

Primary TKAs performed at a single center were retrospectively reviewed. Clinical variables were compared between patients who underwent MUA and those who did not; variables that differed were utilized to identify an appropriately matched control group of non-MUA patients. The MUA group was divided into early (MUA ≤6 weeks from index) and late (>6 weeks) subgroups. Flexion values at multiple time points were compared.

In total, 1729 TKA patients were reviewed; MUA was performed in 62 patients. Patients undergoing MUA were younger (55.2 vs 65.3 years, P < .001) and had higher rates of current smoking (21.0% vs 7.3%, P < .001) and prior procedure (59.7% vs 40.4%, P = .002), most commonly arthroscopy; a control group of patients not requiring MUA, matched on the basis of these variables, was identified. While no difference in pre-TKA flexion existed across groups, final flexion in the early MUA group (106.7°) was equivalent to that of controls (115.6°), while final flexion in the late MUA group was not (101.3°, P = .001).

TKA patients undergoing MUAs were younger, more likely to be current smokers, and more likely to have undergone prior knee surgery. Even in patients with severe initial postoperative limitations in range of motion, MUA within 6 weeks may allow for final outcomes that are equivalent to those experienced by similar patients not requiring manipulation.

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