title: Internal rotation of the tibial component is frequent in stiff total knee arthroplasty.
abstract: BACKGROUND
  Stiffness complicating TKA is a complex and multifactorial problem. We suspected internally rotated components compromised motion because of pain, patellar maltracking, a tight medial flexion gap, and limited femoral rollback on a conforming lateral tibial condyle.
  
  
  OBJECTIVE
  We sought to determine: (1) the incidence of internal rotation of the femoral and tibial components in stiff TKAs; (2) if revision surgery that included correction of rotational positioning improved pain, ROM, and patellar tracking; and (3) if revision altered nonrotational radiographic parameters.
  
  
  METHODS
  From a cohort of 52 patients with TKAs revised for stiffness, we performed CT scans of 34 before and 18 after revision to quantify rotational positioning of the femoral and tibial components using a previously validated scanning protocol.
  
  
  RESULTS
  All 34 patients with TKAs had internal rotation of the summed values for tibial and femoral components (mean, 14.8°; range, 2.7°-33.7°) before revision for stiffness. The incidence of internal rotation was 24 of 34 femoral (mean, 3.1°; internal) and 33 of 34 tibial components (mean, 13.7° internal). Revision arthroplasty improved Knee Society function, knee, and pain scores. Mean extension improved from a contracture of 10.1° to 0.8° and flexion from 71.5° to 100°. Postrevision CT scans confirmed correction of component rotation. Nonrotational parameters were unchanged.
  
  
  CONCLUSIONS
  We recommend CT scanning of patients with stiff TKAs before surgical intervention to identify the presence of internally rotated components.
  
  
  METHODS
  Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, CHA-Hôpital de l'Enfant-Jésus, Laval University, Quebec City, QC, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Bédard
authors.forename: Kelly G
authors.initials: KG
authors.lastname: Vince
authors.forename: John
authors.initials: J
authors.lastname: Redfern
authors.forename: Stacy R
authors.initials: SR
authors.lastname: Collen
mesh_terms: D019645:Arthroplasty, Replacement, Knee; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D011475:Prosthesis Failure; D016059:Range of Motion, Articular; D012086:Reoperation; D012399:Rotation; D013977:Tibia / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed