title: In-vivo kinematics of high-flex posterior-stabilized total knee prosthesis designed for Asian populations.
abstract: The purpose of this study was to determine in-vivo kinematics of our developed posterior-stabilized (PS) total knee prosthesis for Asian populations in comparison with a popular high-flexion PS prosthesis.
  
  
  
  We analyzed 62 osteoarthritic knees: 31 knees with the new PS prosthesis (group A) and 31 knees with a popular high-flexion PS prosthesis (group B). Radiographic knee images were taken during standing, lunge, and kneeling activities. The three-dimensional position and orientation of the implant components were determined using model-based shape matching techniques.
  
  
  
  Group A showed slightly greater implant flexion angles compared with knees with conventional prosthesis at maximum lunge (average: 119 vs. 110°, p = 0.001), and at maximum kneeling (121 vs. 114°, p = 0.004), although the range of motion was not significantly different. The femoral centre positions were more posterior in group A at standing, at 90° lunge, at maximum lunge (-9 and -7 mm, p = 0.004), at 90° kneeling, and at maximum kneeling (-9 vs. -7 mm, p = 0.016), and posterior translations of the femoral center were greater at 90° knee flexion postures. The femoral centre positions had a strong negative correlation with implant flexion angles at maximum lunge in group B (r = -0.893, p < 0.001), but not in group A (p = 0.242).
  
  
  
  The new PS prosthesis designed for Asian knee morphology achieved flexion angles and range of motion at least comparable to that of conventional high-flexion PS prosthesis. The femoral roll-back pattern, however, is different from a conventional knee, reflecting the post/cam design.
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan. watanabe.orj@tmd.ac.jp.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Muneta
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Koga
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Horie
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
authors.forename: Tomomasa
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Otabe
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakagawa
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Katakura
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Sekiya
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D044466:Asian People; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D011474:Prosthesis Design; D016059:Range of Motion, Articular / Q000502:physiology
keywords: Asian populations; Implant design; In-vivo kinematics; Posterior-stabilized; Total knee arthroplasty