Risk Factors for the Need for Manipulation Under Anesthesia Following Total Knee Arthroplasty: A Systematic Review and Meta-analysis.

Introduction: Postoperative knee stiffness following total knee arthroplasty (TKA) is a complication that can result in poor patient outcomes, reduced satisfaction, and even necessitate revision surgery. A common treatment for knee stiffness after TKA is manipulation under anesthesia (MUA). The purpose of this systematic review was to identify and evaluate risk factors for stiffness following primary TKA that resulted in MUA.

Methods: There were six databases searched from inception to October 1, 2023, with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. There were 1,108 abstracts and 390 full-text articles that were screened for those that included risk factors predictive of MUA following TKA. The risk of biases was assessed using Quality in Prognostic Studies (QUIPS) criteria. Meta-analysis using odds ratio was calculated. The database search yielded 53 studies involving 2,931,517 patients.

Results: There were five risk factors that were found to be significant: Younger age (mean differences: -4.23 years; 95% CI [confidence interval]: -8.17 to -0.29), Black race (OR [odds ratio]: 1.94; 95% CI: 1.56 to 2.40), smoking (OR: 1.43; 95% CI: 1.02 to 2.02), preoperative American Society of Anesthesiologists (ASA) score ≤ 2 (OR: 0.64; 95% CI: 0.55 to 0.76), and prior knee procedure (OR: 2.00; 95% CI: 1.49 to 2.69). There was no evidence for sex (OR; 1.30, 95% CI [0.74 to 2.30], P = 0.32), obesity (OR; 0.84, 95% CI [0.67 to 1.05], P = 0.12), and diabetes (OR; 0.85, 95% CI [0.69 to 1.05], P = 0.14) as potential risk factors for stiffness requiring MUA.

Conclusion: The results of our meta-analysis indicate that the Black race, younger age, smoking, preoperative ASA scores ≤ 2, and prior knee surgery are strong evidence as risk factors for postoperative need for MUA.