title: Comparison of transportal and outside-in techniques for posterolateral femoral tunnel drilling in double-bundle ACL reconstruction -three-dimensional CT analysis of bone tunnel geometry.
abstract: OBJECTIVE
  To comparatively analyze the geometry of the posterolateral femoral (PL) tunnel in double-bundle ACL reconstruction between far anteromedial transportal (TP) and outside-in (OI) drilling techniques based on three-dimensional computed tomography (3DCT) image analysis.
  
  
  METHODS
  Forty patients who underwent anatomic double-bundle hamstring ACL reconstruction using the TP (n: 20) or OI (n: 20) method with postoperative CT data available were included in the study. The analyzed parameters were as follows: location of the intraarticular tunnel aperture, tunnel length, bending angle (angulation of the graft at the intraarticular tunnel aperture), and long axis of the tunnel aperture/drill diameter ratio as a parameter of ellipsoidal geometry.
  
  
  RESULTS
  Anatomical tunnel placement was achieved in both groups. Coalition of the AM and PL tunnel apertures was found in 3 knees in the TP group and 1 knee in the OI group, though no significant difference in the rate of this problem was demonstrated between the groups (P: 0.30). The tunnel length was not significantly different between the groups, while the graft bending angle at the tunnel aperture was significantly larger in the OI group than the TP group (99.4° vs. 63.6°). The long axis/drill diameter ratio averaged 1.23 in the TP group and 1.13 in the OI group with significant intergroup difference.
  
  
  CONCLUSIONS
  When drilling the PL femoral tunnel in double-bundle ACL reconstruction, anatomic placement of the intraarticular tunnel aperture was feasible in both the TP and OI techniques. The tunnel aperture was rounder and the graft bending angle in knee extended position at the intraarticular aperture was more acute in the OI technique than the TP technique.
  
  
  METHODS
  Level IV (retrospective comparison of the two patient groups treated at different hospitals).
authors.affiliation: Department of Orthopaedic Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan. Electronic address: shunkazu19810723@hotmail.co.jp.
authors.forename: Shunichiro
authors.initials: S
authors.lastname: Kambara
authors.affiliation: Department of Orthopaedic Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakayama
authors.affiliation: Department of Orthopaedic Surgery, Meiwa General Hospital, 4-31 Agenaruo-cho Nishinomiya, Hyogo 663-8186, Japan.
authors.forename: Motoi
authors.initials: M
authors.lastname: Yamaguchi
authors.affiliation: Department of Orthopaedic Surgery, Meiwa General Hospital, 4-31 Agenaruo-cho Nishinomiya, Hyogo 663-8186, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Matsumoto
authors.affiliation: Department of Orthopaedic Surgery, Meiwa General Hospital, 4-31 Agenaruo-cho Nishinomiya, Hyogo 663-8186, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Sasaki
authors.affiliation: Department of Orthopaedic Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Kashiwa
authors.affiliation: Department of Orthopaedic Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Iseki
authors.affiliation: Department of Orthopaedic Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yoshiya
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries / Q000175:diagnosis / Q000601:surgery*; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001182:Arthroscopy / Q000379:methods; D001804:Blood Transfusion, Autologous; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D011184:Postoperative Period; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013710:Tendons / Q000637:transplantation; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult