title: Women and Minorities Are at Risk of Developing Unexpected Reduction of Preoperative Flexion After Total Knee Arthroplasty.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, New York.
authors.forename: Jared M
authors.initials: JM
authors.lastname: Newman
authors.affiliation: Department of Orthopaedic Surgery, University Hospital of Móstoles, Móstoles, Madrid, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: de Paz Nieves
authors.affiliation: Department of Orthopaedic Surgery, Hospital San Juan de Dios del Aljarafe, Bormujos, Seville, Spain.
authors.forename: Libertad
authors.initials: L
authors.lastname: Cáceres Sánchez
authors.affiliation: Department of Biostatistics and Epidemiology, Hospital for Special Surgery, New York, New York.
authors.forename: Yuo-Yu
authors.initials: YY
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, New York.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Gonzalez Della Valle
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000534:rehabilitation*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D008297:Male; D008875:Middle Aged; D008913:Minority Groups / Q000706:statistics & numerical data; D020370:Osteoarthritis, Knee / Q000601:surgery; D011184:Postoperative Period; D016059:Range of Motion, Articular; D012307:Risk Factors; D012737:Sex Factors
keywords: knee stiffness; outcomes; poor flexion; range of motion; total knee arthroplasty