title: The effect of graft fixation angles on anteroposterior and rotational knee laxity in double-bundle anterior cruciate ligament reconstruction: evaluation using computerized navigation.
abstract: BACKGROUND
  One of the main differences affecting outcome between single-bundle and double-bundle anterior cruciate ligament (ACL) reconstructions may be graft fixation angles and initial force settings; however, there has been little research to investigate these effects in either technique.
  
  
  OBJECTIVE
  Anteroposterior and rotational knee laxities will be less in double-bundle ACL reconstructions than single-bundle reconstructions, and different graft fixation angles affect knee kinematics and pivot-shift phenomenon in double-bundle ACL reconstructions.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Eleven patients who underwent double-bundle ACL reconstruction were included in this study. The anteromedial bundle (AMB) and the posterolateral bundle (PLB) were provisionally fixed to a graft tensioning system during surgery. The graft fixation settings were as follows: (1) AMB only at 20° (A20), (2) PLB only at 20° (P20), (3) AMB at 20° and PLB at 0° (A20P0), (4) AMB at 20° and PLB at 20° (A20P20), and (5) AMB at 20° and PLB at 45° (A20P45). All the grafts were tensioned at a constant stress level. Anterior tibial translation (ATT), internal rotation (IR), and external rotation (ER) at 30° and 90° of knee flexion applied with manual maximum load were measured before graft insertion and in each setting using a navigation system. A pivot-shift test was also evaluated manually with modified International Knee Documentation Committee criteria in each setting.
  
  
  RESULTS
  A20 was less constrained than A20P20 and A20P45 in ATT at 30° and less constrained than A20P45 in IR at 30°. P20 was less constrained than any other settings in ATT at 30° and less constrained than A20P45 in IR at 30°. A20P0 was less constrained than A20P45 in IR at 30° and in ER at 30°. Grade 1 pivot-shift phenomenon persisted in 8 cases in P20, in 4 cases in A20, and in 3 cases in A20P0, whereas no case showed a positive pivot-shift result in A20P20 and A20P45.
  
  
  CONCLUSIONS
  In this in vivo laboratory model, double-bundle ACL reconstruction with fixation of AMB at 20° and PLB at 20° or 45° restored better stability than single AMB or single PLB reconstruction in which the graft was of smaller size.
  
  
  CONCLUSIONS
  In double-bundle ACL reconstruction, fixation of the PLB at 0° might be looser and function worse compared with that of PLB at 20° or 45° when the AMB is fixed at 20°, with the individual variability that should lead to caution until it can be better assessed by surgeons.
authors: Department of Orthopaedic Surgery, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan. koga.orj@tmd.ac.jp
authors: Hideyuki
authors: H
authors: Koga
authors: Takeshi
authors: T
authors: Muneta
authors: Kazuyoshi
authors: K
authors: Yagishita
authors: Young-Jin
authors: YJ
authors: Ju
authors: Ichiro
authors: I
authors: Sekiya
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000601:surgery*; D008297:Male; D012399:Rotation; D013977:Tibia / Q000601:surgery; D019737:Transplants; D016896:Treatment Outcome; D055815:Young Adult