title: The pie-crusting technique using a blade knife for medial collateral ligament release is unreliable in varus total knee arthroplasty.
abstract: OBJECTIVE
  Despite the documented clinical efficacy of the pie-crusting technique for medial collateral ligament (MCL) release in varus total knee arthroplasty, its quantitative effects on medial gaps and safety remain unclear. This study was undertaken to determine the efficacy (quantitative effect and consistency of the number of punctures) and the safety (frequency of early over-release) of the pie-crusting technique for MCL release.
  
  
  METHODS
  From ten pairs of cadaveric knees, one knee from each pair was randomly assigned to undergo pie crusting in extension (group E) or in flexion (group F). Pie crusting was performed in the superficial MCL using a blade until over-release occurred. After every puncture, the incremental medial gap increase was recorded, and the number of punctures required for 2- or 4-mm gap increases was assessed.
  
  
  RESULTS
  In group E, the extension gap increased from 0.8 to 5.0 mm and the flexion gap increased from 0.8 to 3.0 mm. In group F, the extension gap increased from 1.0 to 3.0 mm and the flexion gap increased from 2.6 to 6.0 mm. However, the gap increments were inconsistent with those that followed the preceding blade punctures, and the number of punctures required to increase the gaps by 2 or 4 mm was variable. The number of punctures leading to over-release in group E and group F was 6 ± 1 and 3 ± 1 punctures, respectively. Overall, 70% of over-release occurred earlier than the average number of punctures leading to over-release.
  
  
  CONCLUSIONS
  Pie crusting led to unpredictable gap increments and to frequent early over-release. Surgeons should decide carefully before using the pie-crusting technique for MCL release and should be cautious of performing throughout the procedure, especially when performing in a flexed knee.
  
  
  METHODS
  Therapeutic study, Level I.
authors.affiliation: Catholic Institute for Applied Anatomy, The Catholic University of Korea College of Medicine, Seoul, 137-701, Korea.
authors.forename: Dai-Soon
authors.initials: DS
authors.lastname: Kwak
authors.affiliation: Department of Orthopaedic Surgery, Seoul St. Mary's Hospital, 222 Banpo-daero, Seocho-gu, Seoul, 137-701, Korea.|Department of Orthopaedic Surgery, The Catholic University of Korea College of Medicine, Seoul, 137-701, Korea.
authors.forename: Yong
authors.initials: Y
authors.lastname: In
authors.affiliation: Joint Reconstruction Center, Seoul National University Bundang Hospital, Seongnam-si, Gyeonggi-do, 463-707, Korea.
authors.forename: Tae Kyun
authors.initials: TK
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Seoul St. Mary's Hospital, 222 Banpo-daero, Seocho-gu, Seoul, 137-701, Korea.|Department of Orthopaedic Surgery, The Catholic University of Korea College of Medicine, Seoul, 137-701, Korea.
authors.forename: Han Suk
authors.initials: HS
authors.lastname: Cho
authors.affiliation: Department of Orthopaedic Surgery, Seoul St. Mary's Hospital, 222 Banpo-daero, Seocho-gu, Seoul, 137-701, Korea. hinman74@naver.com.|Department of Orthopaedic Surgery, The Catholic University of Korea College of Medicine, Seoul, 137-701, Korea. hinman74@naver.com.
authors.forename: In Jun
authors.initials: IJ
authors.lastname: Koh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D002102:Cadaver; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000601:surgery*; D016059:Range of Motion, Articular
keywords: Medial collateral ligament release; Pie crusting; Total knee arthroplasty; Varus knee