Predictive Factors for Manipulations Under Anesthesia After Total Knee Arthroplasty: An Analysis of 15,139 Cases

INTRODUCTION: Limited range of motion (ROM) and arthrofibrosis are complications that affect approximately 1 to 13% of patients after primary total knee arthroplasty (TKA). Manipulation under anesthesia (MUA) is the preferred treatment when failure to achieve adequate ROM in the early postoperative period occurs. This study aims to identify predictors for MUA that may guide surgeons in preoperative risk stratification. METHODS: The Premier Healthcare Database was queried to identify patients aged 18 years or older who underwent elective total knee arthroplasty. Patients who underwent manipulation under anesthesia within 90 days of index surgery were compared with patients who did not. Demographics, comorbidities, and medication usage were compared between cohorts using chi-squared and t-tests. Akaike information criterion and Bayesian information criterion minimization was done to create an optimal mixed-effects model to identify risk factors. RESULTS: In total, 975,235 TKAs performed between 2015 and 2021 were identified. Of these, 1.55% (15,139) of patients required MUA. Patients in the MUA group were younger (62.47 ± 9.19 vs. 67.03 ± 9.24, P < 0.001) and more likely to be Black (15.91% vs. 8.29%, P < 0.001). Mixed-effects analysis revealed a decreased risk of MUA associated with perioperative dexamethasone (adjusted odds ratio [aOR] 0.925, 95% CI, 0.889-0.962, P < 0.001), daily prednisone usage (aOR 0.433, 95% CI, 0.347-0.542, P < 0.001), and angiotensin II receptor blockers (ARBs) (aOR 0.882, 95% CI, 0.840-0.927, P < 0.001). DISCUSSION: Younger age, female sex, and Black race were associated with an increased risk of MUA after TKA, while perioperative dexamethasone, daily steroids, and ARB use were protective. These findings may serve to aid surgeons in preoperative risk stratification.