title: Volumetric Damage to the Femoral Physis During Double-Bundle Posterior Cruciate Ligament Reconstruction: A Magnetic Resonance Imaging Computer Modeling Study.
abstract: OBJECTIVE
  The purpose of this study was to use computer models to evaluate the volume of femoral physeal disruption in double-bundle posterior cruciate ligament (PCL) reconstruction in patients with open physes.
  
  
  METHODS
  Ten skeletally immature patients (6 girls and 4 boys) were selected for this study. The magnetic resonance imaging scans of each patient were converted into a 3-dimensional model using computer-aided design/computer-aided manufacturing software. The software allowed the users to differentiate the epiphyseal, physeal, and metaphyseal tissues. This allowed for quantification of volume removed of each tissue type. Furthermore, we used the 3-dimensional models to simulate an anatomic double-bundle technique using 6-, 7-, 8-, and 9-mm-diameter tunnels. The software method reflects an inside-out drilling technique.
  
  
  RESULTS
  For drill holes of all diameters, the posteromedial tunnels exited the knee inferior to the physis, thus avoiding physeal damage. In contrast, all the anterolateral tunnels perforated the physis. The results for the percent of total physis removed are as follows: 6-mm tunnel, 1.79% ± 0.99%; 7-mm tunnel, 2.23% ± 1.19%; 8-mm tunnel, 3.00% ± 1.54%; and 9-mm tunnel, 3.84% ± 1.73%.
  
  
  CONCLUSIONS
  This computer modeling simulation of double-bundle PCL reconstruction in skeletally immature knees found that the posteromedial tunnel avoided disruption of the distal femoral physis. In contrast, the anterolateral tunnel did disrupt the physis with all drill hole sizes (6 to 9 mm), but all had a less than 4% volume of total physis removed.
  
  
  CONCLUSIONS
  A clear understanding of the drill hole position may reduce the volume of physeal injury during double-bundle PCL reconstruction. This study shows that physeal disruption of less than the experimental 7% threshold that has been shown to cause physeal arrest may not cause arrest, but this is still speculative.
authors.affiliation: St. Luke's Sports Medicine, St. Children's Hospital, Boise, Idaho, U.S.A.; Department of Orthopedics, University of Utah, Salt Lake City, Utah, U.S.A.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Shea
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina, U.S.A.
authors.forename: Nathan L
authors.initials: NL
authors.lastname: Grimm
authors.affiliation: University of Utah School of Medicine, University of Utah, Salt Lake City, Utah, U.S.A.
authors.forename: Francesca R
authors.initials: FR
authors.lastname: Nichols
authors.affiliation: University of Utah School of Medicine, University of Utah, Salt Lake City, Utah, U.S.A.. Electronic address: jacobsjc013@gmail.com.
authors.forename: John C
authors.initials: JC
authors.lastname: Jacobs
mesh_terms: D016118:Anterior Cruciate Ligament / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D002648:Child; D002675:Child, Preschool; D003198:Computer Simulation; D004838:Epiphyses / Q000473:pathology / Q000601:surgery; D005260:Female; D005269:Femur / Q000293:injuries* / Q000473:pathology; D006801:Humans; D021621:Imaging, Three-Dimensional; D007431:Intraoperative Complications / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D016119:Posterior Cruciate Ligament / Q000293:injuries / Q000601:surgery*; D019651:Plastic Surgery Procedures / Q000009:adverse effects*