title: The Correlation of Tunnel Position, Orientation and Tunnel Enlargement in Outside-in Single-Bundle Anterior Cruciate Ligament Reconstruction.
abstract: OBJECTIVE
  Tunnel widening after anterior cruciate ligament (ACL) reconstruction is a frequently described phenomenon. The possible etiology is multi-factorial with some mechanical and biological factors. Among those, we intended to determine the relation between the location and orientation of the femoral tunnel and the femoral tunnel enlargement after outside-in single-bundle ACL reconstruction.
  
  
  METHODS
  A retrospective study including 42 patients who received single-bundle ACL reconstruction with the outside-in technique was conducted. Femoral and tibial tunnel locations were evaluated with the quadrant method and bird's-eye view using volume-rendering computed tomography. The angle and diameter of bone tunnel and the degree of tunnel enlargement were evaluated using standard radiographs.
  
  
  RESULTS
  The degree of femoral tunnel enlargements were 42% and 36% on the anteroposterior (AP) and lateral radiographs, respectively, and the degree of tibial tunnel enlargements were 22% and 23%, respectively. Shallower location of the femoral tunnel was significantly correlated with greater femoral tunnel enlargement on the AP radiograph (r=0.998, p=0.004) and the lateral radiograph (r=0.72, p=0.005) as was the higher location of the femoral tunnel on the AP radiograph (r=-0.47, p=0.01) and the lateral radiograph (r=-0.36, p=0.009) at 12 months after surgery.
  
  
  CONCLUSIONS
  This study revealed that more anterior and higher location and more horizontal orientation of the femoral tunnel in coronal plane could result in widening of the femoral tunnel in outside-in single-bundle ACL reconstruction.
authors.affiliation: Department of Orthopedic Surgery, Ewha Womans University Mokdong Hospital, Seoul, Korea.
authors.forename: Young Won
authors.initials: YW
authors.lastname: Ko
authors.affiliation: Department of Orthopedic Surgery, Ewha Womans University Mokdong Hospital, Seoul, Korea.
authors.forename: Seung Jun
authors.initials: SJ
authors.lastname: Rhee
authors.affiliation: Department of Orthopedic Surgery, Ewha Womans University Mokdong Hospital, Seoul, Korea.
authors.forename: In Woo
authors.initials: IW
authors.lastname: Kim
authors.affiliation: Department of Orthopedic Surgery, Ewha Womans University Mokdong Hospital, Seoul, Korea.
authors.forename: Jae-Doo
authors.initials: JD
authors.lastname: Yoo
keywords: Anterior cruciate ligament; Knee; Outside-in technique; Tunnel enlargement