title: Intra-operative gaps affect outcome and postoperative kinematics in vivo following cruciate-retaining total knee arthroplasty.
abstract: OBJECTIVE
  The following investigation evaluates the effect of intra-operative gaps after posterior cruciate ligament-retaining total knee arthroplasty using two-dimensional/three-dimensional registration and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).
  
  
  METHODS
  Patients were divided into two groups according to their 90°-0° component gap changes using a device designed by our laboratory. The wide gap group was defined as more than 3 mm (4.3 ± 0.7 mm), and the narrow gap group was defined as less than 3 mm (1.3 ± 1.3 mm).
  
  
  RESULTS
  Under non-WB (weight bearing) conditions, the wide flexion gap group (N = 10) showed a significant anterior displacement of the medial femoral condyle as compared with the narrow flexion gap group (N = 20). Despite no significant differences observed under WB conditions, both femoral condyle positions during flexion were significantly more posterior than during extension. WOMAC of the tight gap group showed worse scores for two functional items demanding knee flexion (bending to floor and getting on/off toilet).
  
  
  CONCLUSIONS
  The large flexion gap could influence the late rollback under non-WB conditions and better WOMAC functional scores in the flexion items. Three to four millimetre laxity at 90°-0° component gaps may be adequate and might be necessary to carry out daily life activities.
authors.affiliation: Department of Orthopaedic Surgery, Chugoku Rousai Hospital, 1-5-1 Hirotagaya, Kure, Hiroshima, 737-0193, Japan. eisaku-fjm@umin.ac.jp.
authors.forename: Eisaku
authors.initials: E
authors.lastname: Fujimoto
authors.affiliation: Department of Orthopaedic Surgery, Chugoku Rousai Hospital, 1-5-1 Hirotagaya, Kure, Hiroshima, 737-0193, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Sasashige
authors.affiliation: Department of Orthopaedic Biomaterial Science, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Tomita
authors.affiliation: Department of Orthopaedic Surgery, Chugoku Rousai Hospital, 1-5-1 Hirotagaya, Kure, Hiroshima, 737-0193, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Sasaki
authors.affiliation: Department of Orthopaedic Surgery, Chugoku Rousai Hospital, 1-5-1 Hirotagaya, Kure, Hiroshima, 737-0193, Japan.
authors.forename: Yoriko
authors.initials: Y
authors.lastname: Touten
authors.affiliation: Department of Orthopaedic Surgery, Chugoku Rousai Hospital, 1-5-1 Hirotagaya, Kure, Hiroshima, 737-0193, Japan.
authors.forename: Yuusuke
authors.initials: Y
authors.lastname: Fujiwara
authors.affiliation: Department of Orthopaedic Surgery, Hiroshima University, Hiroshima, Japan.
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Ochi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D016119:Posterior Cruciate Ligament / Q000601:surgery*; D011184:Postoperative Period; D016059:Range of Motion, Articular; D016896:Treatment Outcome; D016474:Weight-Bearing
keywords: 2D/3D registration; Component gap; Cruciate-retaining total knee arthroplasty; Kinematics; Posterior cruciate ligament; WOMAC