title: How much hamstring graft needs to be in the femoral tunnel? A MOON cohort study.
abstract: BACKGROUND
  Recent evidence that smaller hamstring graft diameter is associated with increased failure risk following anterior cruciate ligament (ACL) reconstruction has increased the popularity of graft configurations that increase graft diameter at the expense of graft length. A key question is how much graft needs to be in contact with the femoral tunnel to ensure that healing occurs. We hypothesize that no difference in two-year patient-reported outcomes or failure risk exists based on the amount of graft in the femoral tunnel.
  
  
  METHODS
  Through the use of prospectively collected cohort data augmented with retrospective chart review, 120 of 181 consecutive patients (66.3 %) undergoing primary ACL reconstruction with hamstring autograft were evaluated. Patient and surgical factors along with pre-operative and two-year postoperative knee injury and osteoarthritis outcome score (KOOS) and International Knee Documentation Committee (IKDC) scores and whether each patient underwent revision ACL reconstruction during the two-year follow-up period were recorded.
  
  
  RESULTS
  No differences in two-year patient-reported outcome scores were noted between patients with graft length in the femoral tunnel less than 25 mm and those with graft length in the femoral tunnel of at least 25 mm. Controlling for age, sex, BMI, and femoral tunnel technique, no correlation was noted between KOOS or IKDC scores and either the length of graft in the femoral tunnel or the contact area between the graft and the tunnel.
  
  
  CONCLUSIONS
  Variation of the length of hamstring autograft in the femoral tunnel between 14 and 35 mm does not predict KOOS or IKDC scores at 2 years postoperative.
authors.affiliation: OSU Sports Medicine, Sports Health and Performance Institute, Department of Orthopaedics, The Ohio State University, 2050 Kenny Road, Suite 3100, Columbus, OH 43221-3502, USA.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Mariscalco
authors.affiliation: OSU Sports Medicine, Sports Health and Performance Institute, Department of Orthopaedics, The Ohio State University, 2050 Kenny Road, Suite 3100, Columbus, OH 43221-3502, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Magnussen
authors.affiliation: OSU Sports Medicine, Sports Health and Performance Institute, Department of Orthopaedics, The Ohio State University, 2050 Kenny Road, Suite 3100, Columbus, OH 43221-3502, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Mitchell
authors.affiliation: OSU Sports Medicine, Sports Health and Performance Institute, Department of Orthopaedics, The Ohio State University, 2050 Kenny Road, Suite 3100, Columbus, OH 43221-3502, USA.
authors.forename: Angela D
authors.initials: AD
authors.lastname: Pedroza
authors.affiliation: Cleveland Clinic Sports Health Center, The Cleveland Clinic Foundation, Cleveland, OH, USA.
authors.forename: Morgan H
authors.initials: MH
authors.lastname: Jones
authors.affiliation: Cleveland Clinic Sports Health Center, The Cleveland Clinic Foundation, Cleveland, OH, USA.
authors.forename: Jack T
authors.initials: JT
authors.lastname: Andrish
authors.affiliation: Cleveland Clinic Sports Health Center, The Cleveland Clinic Foundation, Cleveland, OH, USA.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Parker
authors.affiliation: OSU Sports Medicine, Sports Health and Performance Institute, Department of Orthopaedics, The Ohio State University, 2050 Kenny Road, Suite 3100, Columbus, OH 43221-3502, USA.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Kaeding
authors.affiliation: OSU Sports Medicine, Sports Health and Performance Institute, Department of Orthopaedics, The Ohio State University, 2050 Kenny Road, Suite 3100, Columbus, OH 43221-3502, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Flanigan
keywords: ACL reconstruction; Femoral tunnel; Hamstring graft; Risk factors