title: An in Vivo 3D Computed Tomographic Analysis of Femoral Tunnel Geometry and Aperture Morphology Between Rigid and Flexible Systems in Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Transportal Technique.
abstract: OBJECTIVE
  The aim of this study was to compare femoral tunnel length, femoral graft-bending angle, posterior wall breakage, and femoral aperture morphologic characteristics between rigid and flexible systems after double-bundle (DB) anterior cruciate ligament (ACL) reconstruction using the transportal (TP) technique.
  
  
  METHODS
  We evaluated 3-dimensional computed tomography (3D-CT) results for 54 patients who underwent DB ACL reconstruction using the TP technique with either a flexible system (n = 27) or a rigid system (n = 27). The femoral tunnel length, femoral graft-bending angle, posterior wall breakage, femoral tunnel aperture height to width (H:W) ratio, aperture axis angle, and femoral tunnel position were assessed using OsiriX Imaging Software and Geomagic Qualify 2012 (Geomagic, Cary, NC).
  
  
  RESULTS
  The mean anteromedial (AM) femoral tunnel length of the flexible group was significantly longer than that of the rigid group (P = .009). The mean femoral graft-bending angles in the flexible group were significantly less acute than those in the rigid group (AM, P < .001; posterolateral [PL], P = .003]. Posterior wall breakage was observed in both groups (P = 1.00). The mean H:W ratios in the rigid group were significantly larger (more elliptical) than those of the flexible group (AM, P < .001; PL, P = .006). The mean aperture axis angle of the PL femoral tunnel in the rigid group was more parallel to the femoral shaft axis than that in the flexible group (P < .001). There were no significant differences in femoral tunnel position between the 2 groups.
  
  
  CONCLUSIONS
  The AM femoral tunnel length and the AM/PL femoral graft-bending angle of the flexible system were significantly longer and less acute than those of the rigid system. However, the aperture morphologic characteristics of the AM/PL femoral tunnel and the aperture axis angle of the PL femoral tunnel in the rigid system were significantly more elliptical and closer to parallel to the femoral shaft axis than those of the flexible system.
  
  
  METHODS
  Level III, retrospective comparative study.
authors.affiliation: Department of Orthopaedic Surgery, Korea University College of Medicine, Ansan Hospital, Ansan, Gyeonggi-do, Republic of Korea.
authors.forename: Jae Gyoon
authors.initials: JG
authors.lastname: Kim
authors.affiliation: School of Mechanical Engineering, Korea University, Seoul, Republic of Korea.
authors.forename: Min Ho
authors.initials: MH
authors.lastname: Chang
authors.affiliation: Department of Orthopaedic Surgery, Korea University College of Medicine, Guro Hospital, Seoul, Republic of Korea.
authors.forename: Hong Chul
authors.initials: HC
authors.lastname: Lim
authors.affiliation: Department of Orthopaedic Surgery, Korea University College of Medicine, Guro Hospital, Seoul, Republic of Korea.
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Bae
authors.affiliation: Department of Orthopaedic Surgery, Korea University College of Medicine, Guro Hospital, Seoul, Republic of Korea.
authors.forename: Seung Yup
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, Sungkyunkwan University School of Medicine, Kangbuk Samsung Hospital, Seoul, Republic of Korea.
authors.forename: Jin Hwan
authors.initials: JH
authors.lastname: Ahn
authors.affiliation: Department of Orthopaedic Surgery, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: mdwang88@gmail.com.
authors.forename: Joon Ho
authors.initials: JH
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000295:instrumentation / Q000379:methods*; D005260:Female; D005269:Femur / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods; D019737:Transplants; D055815:Young Adult