title: Evaluation and Comparison of Femoral Tunnel Placement During Anterior Cruciate Ligament Reconstruction Using 3-Dimensional Computed Tomography: Effect of Notchplasty on Transtibial and Medial Portal Drilling.
abstract: BACKGROUND
  Advocates of medial portal drilling claim that the transtibial technique results in a more vertical positioning of the graft, which could lead to subsequent failure and/or a residual pivot shift on postoperative examination. However, advocates of transtibial drilling state that with appropriate placement and adequate notchplasty, their technique places the graft in a more anatomically correct position on the wall, negating the resultant potential for pivot shift and early postoperative failure.
  
  
  OBJECTIVE
  Transtibial femoral drilling can adequately reproduce the femoral origin of the anterior cruciate ligament (ACL) and place the graft in an anatomical position equivalent to medial portal drilling.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Ten matched-pair cadaveric knees (N = 20) were scanned using computed tomography (CT), and 3-dimensional images of the native ACL origin were reconstructed. The matched pairs were then randomized into transtibial and medial portal groups. The femoral tunnel was drilled in each knee according to group. A bamboo skewer was placed in the femoral tunnel, and the knees underwent a second CT scan. Arthroscopic notchplasty was performed, and the femoral tunnels were redrilled. Radiographs confirmed placement, and the post-notchplasty tunnel was reamed with a 4-mm reamer. The knees underwent a third CT scan. CT scans compared femoral tunnel placement with the native ACL footprint before and after notchplasty.
  
  
  RESULTS
  The post-notchplasty transtibial group revealed an average of 68.3% coverage of the native ACL femoral origin. The medial portal group revealed an average of 60.8% coverage, with 1 instance of perforation of the posterior cortex. There were no instances of perforation in the transtibial group.
  
  
  CONCLUSIONS
  Both drilling techniques place the graft in an anatomically correct position.
  
  
  CONCLUSIONS
  Transtibial drilling of the femur can adequately place the entry tunnel at the origin of the ACL's native footprint.
authors.affiliation: American Sports Medicine Institute, Birmingham, Alabama, USA.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Dugas
authors.affiliation: American Sports Medicine Institute, Birmingham, Alabama, USA.
authors.forename: Jesse L
authors.initials: JL
authors.lastname: Pace
authors.affiliation: American Sports Medicine Institute, Birmingham, Alabama, USA.
authors.forename: Becky
authors.initials: B
authors.lastname: Bolt
authors.affiliation: Radiology Associates Birmingham, Birmingham, Alabama, USA.
authors.forename: Shane A
authors.initials: SA
authors.lastname: Wear
authors.affiliation: American Sports Medicine Institute, Birmingham, Alabama, USA.
authors.forename: David P
authors.initials: DP
authors.lastname: Beason
authors.affiliation: American Sports Medicine Institute, Birmingham, Alabama, USA.
authors.forename: E Lyle
authors.initials: EL
authors.lastname: Cain
keywords: anterior cruciate ligament; femoral tunnel; medial portal; transtibial