title: In vivo kinematics comparison of fixed- and mobile-bearing total knee arthroplasty during deep knee bending motion.
abstract: OBJECTIVE
  The in vivo kinematics of fixed-bearing and mobile-bearing total knee prostheses remains unclear, particularly for knee flexion over 120°. The purpose of this study was to compare the in vivo kinematics of fixed-bearing and mobile-bearing posterior-stabilized prosthesis during deep knee bending with knee flexion exceeding 120° under weight-bearing conditions.
  
  
  METHODS
  In vivo kinematics was analysed for 20 patients implanted with either a fixed-bearing posterior-stabilized or mobile-bearing posterior-stabilized prosthesis. Under fluoroscopic surveillance, each patient performed weight-bearing deep knee bending. Motion between each component was analysed using a two- to three-dimensional registration technique, which uses computer-assisted design models to reproduce the spatial positions of the femoral and tibial components from single-view fluoroscopic images.
  
  
  RESULTS
  Patients who had fixed-bearing prostheses experienced posterior femoral rollback at a mean of 1.4 mm (SD 1.6) of the medial condyle, whereas patients who had mobile-bearing prostheses experienced 0.8 mm (SD 1.2). The posterior femoral rollback of the femoral lateral condyle in patients with a fixed-bearing prosthesis was a mean of 6.4 mm (SD 1.7) motion in the posterior direction, whereas patients who had a mobile-bearing prosthesis had 6.5 mm (SD 2.4) motion. The mean tibial internal rotation was 7.5° (SD 2.1) for fixed-bearing prosthesis and 9.2° (SD 3.2) for mobile-bearing prosthesis.
  
  
  CONCLUSIONS
  The present results demonstrated that the fixed-bearing and mobile-bearing posterior-stabilized designs had similar posterior condylar translation and tibial axial rotation during weight-bearing deep knee flexion exceeding 120°.
authors.affiliation: The Orthopedic Department, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Shi
authors.forename: Bin
authors.initials: B
authors.lastname: Shen
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Pengde
authors.initials: P
authors.lastname: Kang
authors.forename: Zongke
authors.initials: Z
authors.lastname: Zhou
authors.forename: Fuxing
authors.initials: F
authors.lastname: Pei
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D005471:Fluoroscopy; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D011474:Prosthesis Design; D016059:Range of Motion, Articular / Q000502:physiology*; D012189:Retrospective Studies; D012399:Rotation; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery; D016474:Weight-Bearing