Women and Minorities Are at Risk of Developing Unexpected Reduction of Preoperative Flexion After Total Knee Arthroplasty.

Background: Reduced flexion after total knee arthroplasty (TKA) compared to the preoperative values can affect patient's activities of daily living and lead to patient dissatisfaction. The aim of this study was to determine preoperative risk factors for developing a decrease in knee flexion after a primary TKA.

Methods: We identified 37 knees diagnosed with osteoarthritis with a preoperative knee flexion ≥120° but a 12-month postoperative range of motion (ROM) ≤110°. A random sample of 111 patients (1:3) from the same database, whose knees had a preoperative and 12-month postoperative ROM ≥120°, based on a diagnosis of primary osteoarthritis and no previous open knee surgery, were selected as the controls.

Results: We found female gender, black ethnicity, and the low preoperative knee-specific Knee Society Score to be significant risk factors for developing a reduction of knee flexion after TKA with odds ratios of 3.48, 5.11, and 0.95, respectively.

Conclusion: In the absence of the well-recognized preoperative risk factors for a limited postoperative ROM, female patients, minorities, and those with lower knee-specific Knee Society Scores are at an increased risk of developing a decrease in flexion after an elective primary TKA.