title: Graft orientation influences the knee flexion moment during walking in patients with anterior cruciate ligament reconstruction.
abstract: BACKGROUND
  Anterior cruciate ligament graft orientation has been proposed as a potential mechanism for failure of single-bundle anterior cruciate ligament reconstruction and has been considered important in the restoration of normal ambulatory knee mechanics.
  
  
  OBJECTIVE
  To evaluate the possibility that patients adapt their mechanics of walking to the orientation of the anterior cruciate ligament graft. This was determined by testing the hypothesis that peak external knee flexion moment (net quadriceps moment) during walking in patients with anterior cruciate ligament reconstruction is correlated with coronal and sagittal anterior cruciate ligament graft orientations.
  
  
  METHODS
  Cross-sectional study; Level of evidence, 3.
  
  
  METHODS
  Gait analysis was performed to assess dynamic knee function during walking in 17 subjects with unilateral anterior cruciate ligament reconstructions. Magnetic resonance imaging was used to measure coronal and sagittal anterior cruciate ligament graft orientations.
  
  
  RESULTS
  A negative correlation was observed between peak external knee flexion moment during walking and coronal angle of the anterior cruciate ligament graft (1.0 m/s walking speed, r = -0.87, P < .001; 1.3 m/s, r = -0.66, P = .004; 1.6 m/s, r = -0.24, P > .05); no correlation was found with the sagittal graft angle (1.0 m/s walking speed, r = 0.21, P > .05; 1.3 m/s, r = 0.20, P > .05; 1.6 m/s, r = 0.13, P > .05).
  
  
  CONCLUSIONS
  The negative correlation between peak external knee flexion moment during walking and the coronal angle of the anterior cruciate ligament graft indicates that as the anterior cruciate ligament graft is placed in a more vertical coronal orientation, patients reduce their net quadriceps usage during walking.
  
  
  CONCLUSIONS
  This finding supports the hypothesis that graft placement plays a critical role in the restoration of normal ambulatory mechanics after anterior cruciate ligament reconstruction and thus could provide a partial explanation for the increased incidence of premature osteoarthritis at long-term follow-up in patients with anterior cruciate ligament reconstruction.
authors.affiliation: Biomechanical Engineering, Department of Mechanical Engineering, Stanford University, Stanford, CA 94305-4038, USA. sscanlan@stanford.edu
authors.forename: Sean F
authors.initials: SF
authors.lastname: Scanlan
authors.forename: Katerina
authors.initials: K
authors.lastname: Blazek
authors.forename: Ajit M W
authors.initials: AM
authors.lastname: Chaudhari
authors.forename: Marc R
authors.initials: MR
authors.lastname: Safran
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Andriacchi
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000502:physiology / Q000601:surgery*; D050376:Bone-Patellar Tendon-Bone Grafting / Q000009:adverse effects*; D003430:Cross-Sectional Studies; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D055815:Young Adult