title: The importance of tibial tunnel placement in anatomic double-bundle anterior cruciate ligament reconstruction.
abstract: OBJECTIVE
  The purposes of this study were to measure the anterior edge of the tibial tunnel after anatomic anterior cruciate ligament (ACL) reconstruction on lateral radiographs and to determine whether the difference in tibial tunnel placement affects postoperative outcomes.
  
  
  METHODS
  For 60 patients who underwent anatomic double-bundle ACL reconstruction with semitendinosus tendon, we evaluated the side-to-side difference in anterior tibial translation on stress radiographs, as well as rotational stability by the pivot-shift test, 2 years after surgery. Loss of extension (LOE) was evaluated on lateral radiographs of both knees in full extension, and graft integrity was assessed during second-look arthroscopy 1 to 2 years after surgery. On true lateral radiographs, we measured the anterior placement percentage of the tibial tunnel using the method described by Amis and Jakob. The cutoff value was set at 25% of the mean value of the anterior edge of the ACL that Amis and Jakob reported, and patients were divided into 2 groups (27 in the anterior group and 33 in the posterior group). Postoperative clinical results were compared between the groups.
  
  
  RESULTS
  The mean anterior placement percentage was 26.0% ± 4.1%. The postoperative mean side-to-side difference was 1.4 ± 2.7 mm for the anterior group and 3.0 ± 2.7 mm for the posterior group, a significant difference (P < .05). The positive ratio of the pivot-shift test was not significantly different between groups (P > .05). Mean LOE in the anterior and posterior groups was 0.9° ± 3.0° and -0.8° ± 4.0°, respectively; the difference was not significant (P > .05). Five of 27 knees in the anterior group and 5 of 33 knees in the posterior group had superficial graft laceration or elongation, which was not significantly different (P > .05).
  
  
  CONCLUSIONS
  Anterior placement of the tibial tunnel in anatomic double-bundle ACL reconstruction leads to better anterior knee stability than posterior placement does. Anterior tibial tunnel placement inside the footprint did not increase the incidence of LOE and graft failure.
  
  
  METHODS
  Level IV, therapeutic case series.
authors.affiliation: Department of Orthopaedic Surgery, Social Insurance Gunma Chuo General Hospital, Maebashi, Japan. kazuhisa@zg7.so-net.ne.jp
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Hatayama
authors.forename: Masanori
authors.initials: M
authors.lastname: Terauchi
authors.forename: Kenichi
authors.initials: K
authors.lastname: Saito
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Higuchi
authors.forename: Shinya
authors.initials: S
authors.lastname: Yanagisawa
authors.forename: Kenji
authors.initials: K
authors.lastname: Takagishi
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001182:Arthroscopy / Q000379:methods; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000517:prevention & control*; D007719:Knee Joint / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011859:Radiography; D016059:Range of Motion, Articular; D012399:Rotation; D024162:Second-Look Surgery / Q000379:methods; D013710:Tendons / Q000601:surgery / Q000637:transplantation; D013977:Tibia / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult