title: Capsular release around the intercondylar notch increases the extension gap in posterior-stabilized rotating-platform total knee arthroplasty.
abstract: BACKGROUND
  In posterior-stabilized (PS) total knee arthroplasty (TKA), various post-cam designs can be used. A larger cam of the femoral component may tighten the extension gap. Few studies have investigated the relationship between capsular release around the intercondylar notch and the extension gap. The aim of this study was to assess the effect of capsular release around the intercondylar notch on the extension gap.
  
  
  METHODS
  Forty-eight patients (54 knees) who underwent PS rotating-platform TKA (PFC Sigma RP-F) were enrolled retrospectively. We measured the extension gap with and without a femoral trial using a knee balancer, applying a joint distraction force of 44lb. When an intraoperative flexion contracture of >5° persisted, we performed a capsular release approximately 10mm cranial to the intercondylar notch. After full knee extension was achieved, the extension gap was measured again.
  
  
  RESULTS
  Thirty knees required capsular release. With a trial, the medial and lateral differences between the extension gaps before and after capsular release were 1.7mm (p<0.0001) and 2.3mm (p<0.0001), respectively. Without a trial, the gaps were enlarged by 0.4mm (p=0.0452) and 0.6mm (p=0.0215), respectively. Twenty-four knees did not require release. No significant differences were noted in the range of motion at one-year follow-up between the two cohorts.
  
  
  CONCLUSIONS
  With PS rotating-platform TKA, capsular release around the intercondylar notch is found to increase the extension gap and may prevent postoperative flexion contracture.
  
  
  METHODS
  Level III, retrospective comparative study.
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, Osaka, Japan. Electronic address: ort141@osaka-med.ac.jp.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Okamoto
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, Osaka, Japan.
authors.forename: Mikio
authors.initials: M
authors.lastname: Nakajima
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, Osaka, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Jotoku
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, Osaka, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Otsuki
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, Osaka, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Neo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation / Q000379:methods*; D005260:Female; D005269:Femur / Q000601:surgery; D056305:Genu Varum / Q000601:surgery; D006801:Humans; D057913:Joint Capsule Release / Q000379:methods*; D007719:Knee Joint / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D016059:Range of Motion, Articular; D012189:Retrospective Studies
keywords: Cam; Capsular release; Extension gap; Flexion contracture; Total knee arthroplasty