title: Different intraoperative kinematics with comparable clinical outcomes of ultracongruent and posterior stabilized mobile-bearing total knee arthroplasty.
abstract: OBJECTIVE
  There remains no consensus as to whether mobile total knee arthroplasty (TKA) should use a posterior cruciate ligament-sacrificing ultracongruent (UC) or a posterior cruciate ligament-substituting posterior stabilized (PS) prosthesis. The purpose of this study was to assess intraoperative kinematics and clinical outcomes of UC and PS rotating platform mobile-bearing TKA.
  
  
  METHODS
  In this randomized controlled study, mobile UC TKA prostheses (n = 45) were compared with mobile PS TKA prostheses (n = 45) with regard to intraoperative kinematics and clinical outcomes. The passive kinematic study using intraoperative navigation system included anterior/posterior translation, varus/valgus alignment and rotation of femur during flexion. The patients were clinically and radiographically evaluated over a 3-year follow-up.
  
  
  RESULTS
  Paradoxical anterior translation of the femur was 10.8 ± 5.2 mm in the UC knee from 0° to 82° of knee flexion and 8.7 ± 3.0 mm in the PS knee from 0° to 70° of knee flexion (p = 0.027). Paradoxical internal rotation of the femur was 5.8° in the UC knees and 9.9° in the PS knees (p = 0.003). But, there was no significant difference between the groups in regard to the coronal alignment. There was no significant difference in the range of motion, KS knee scores, KS function scores, and WOMAC index scores.
  
  
  CONCLUSIONS
  Despite different intraoperative kinematics between mobile UC and mobile PS TKA, neither design reproduced physiologic knee kinematics and there was no difference in clinical outcomes between the two groups. The clinical relevance of the study is that despite different intraoperative kinematics, UC design can be a considerable alternative to PS design in mobile-bearing TKA in respect of clinical outcomes.
  
  
  METHODS
  II.
authors.affiliation: Department of Orthopaedic Surgery, Hallym University Hospital, Chuncheon, 77, Sakju-ro, Chuncheon-si, Gangwon-do, 200-704, Korea.
authors.forename: Tae Woo
authors.initials: TW
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Seoul Jaeil Hospital, 70, Jisan-ro, Pyeongtaek-si, Gyeonggi-do, Korea.
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, 82, Gumi-ro 173 Beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 464-707, Korea.
authors.forename: Sang Cheol
authors.initials: SC
authors.lastname: Seong
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Hospital, 101 Daehang-ro, Jongno-gu, Seoul, 110-744, Korea.
authors.forename: Sahnghoon
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, Daehan Hospital, 301, Dobong-ro, Ganbuk-gu, Seoul, 132-703, Korea.
authors.forename: Jak
authors.initials: J
authors.lastname: Jang
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Hospital, 101 Daehang-ro, Jongno-gu, Seoul, 110-744, Korea. leemc@snu.ac.kr.
authors.forename: Myung Chul
authors.initials: MC
authors.lastname: Lee
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007432:Intraoperative Period; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D020370:Osteoarthritis, Knee / Q000503:physiopathology* / Q000601:surgery*; D016119:Posterior Cruciate Ligament / Q000601:surgery; D011446:Prospective Studies; D011474:Prosthesis Design; D016059:Range of Motion, Articular / Q000502:physiology; D012399:Rotation
keywords: Clinical outcome; Kinematics; Posterior stabilized; Total knee arthroplasty; Ultracongruent