title: Influence of intra-operative parameters on postoperative early recovery of active knee flexion in posterior-stabilized total knee arthroplasty.
abstract: OBJECTIVE
  Active knee flexion is more important for daily activities than passive knee flexion. The hypothesis is that the intra-operative parameters such as osteotomized bone thickness and soft tissue balance affect the postoperative active flexion angle in total knee arthroplasty (TKA). Therefore, we evaluate the influence of intra-operative parameters on postoperative early recovery of active flexion after posterior-stabilized (PS) TKA.
  
  
  METHODS
  The subjects were 45 osteoarthritic knees undergoing primary PS TKA with anterior-reference technique. Intra-operative soft tissue balance was measured using an offset type tensor, and each osteotomized bone thickness was also measured. Pre- and postoperative active knee flexion angles were measured using lateral radiographs. Liner regression analysis was used to determine the influence of these intra-operative parameters on postoperative active flexion angles or recovery of active flexion angles.
  
  
  RESULTS
  Pre-operative flexion angle was positively correlated with postoperative flexion angle (R = 0.52, P = 0.0002). Postoperative flexion angle was negatively correlated with the osteotomized bone thickness of femoral medial posterior condyle (R = -0.37, P = 0.012), and femoral lateral posterior condyle (R = -0.36, P = 0.015). Recovery of flexion angle was slightly negatively correlated with gap difference calculated by subtracting joint gap at extension from that at flexion between osteotomized surfaces (R = -0.30, P = 0.046).
  
  
  CONCLUSIONS
  The osteotomized bone thickness of the femoral posterior condyle is a significant independent factor of postoperative flexion angles. This indicates that the restoration of the posterior condyle offset may lead to larger postoperative active flexion angles in PS TKA.
authors.affiliation: Department of Orthopaedic Surgery, Steel Memorial Hirohata Hospital, Himeji, Japan, kant_kantona@yahoo.co.jp.
authors.forename: Kanto
authors.initials: K
authors.lastname: Nagai
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Muratsu
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Akihiro
authors.initials: A
authors.lastname: Maruo
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Miya
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Kuroda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurosaka
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D005269:Femur / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000502:physiology* / Q000601:surgery*; D016014:Linear Models; D008297:Male; D020370:Osteoarthritis, Knee / Q000601:surgery*; D010027:Osteotomy; D011184:Postoperative Period; D016059:Range of Motion, Articular / Q000502:physiology*; D020127:Recovery of Function / Q000502:physiology*; D012189:Retrospective Studies; D013977:Tibia / Q000601:surgery; D016896:Treatment Outcome