title: Tension changes within the bundles of anatomic double-bundle anterior cruciate ligament reconstruction at different knee flexion angles: a study using a 3-dimensional finite element model.
abstract: OBJECTIVE
  The aim of this study was to determine the change in length and tension of the reconstructed anterior cruciate ligament (ACL) double bundles at different knee flexion angles by use of a 3-dimensional finite element model.
  
  
  METHODS
  The right knees of 12 living subjects were scanned with a high-resolution computed tomography scanner at 0°, 45°, 90°, and 135° of knee flexion. Several modeling programs were used to simulate double-bundle ACL reconstruction. A finite element model of each bundle with a tension of 20 N was put into each tunnel followed by fixation of the bundles. The tension and length changes of each bundle at different knee flexion angles were assessed.
  
  
  RESULTS
  For the anteromedial bundle, the length decreased gradually between 45° and 90° of knee flexion and then reached a plateau, whereas the length of the posterolateral bundle significantly decreased at 45° and 90° of flexion but then increased at full flexion. The reaction force of the anteromedial graft slightly decreased at 45° and then remained constant between 90° and 135° of knee flexion. The reaction force of the posterolateral bundle at full extension slightly decreased at 45° and 90° of flexion, followed by a rebound increase at 135°.
  
  
  CONCLUSIONS
  We found that both bundles functioned throughout the arc of flexion with consistency in tension, although their lengths decreased. The 2 ACL grafts did not function in a reciprocal manner, unlike previous descriptions.
  
  
  CONCLUSIONS
  The data obtained for length and tension versus flexion angle have the potential to suggest the appropriate knee position for graft fixation and tensioning to be near extension in clinical situations.
authors.affiliation: Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, Republic of Korea.
authors.forename: Heon Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Young-Jin
authors.initials: YJ
authors.lastname: Seo
authors.forename: Hak-Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Trung
authors.initials: T
authors.lastname: Nguyenn
authors.forename: Nagraj S
authors.initials: NS
authors.lastname: Shetty
authors.forename: Yon-Sik
authors.initials: YS
authors.lastname: Yoo
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging*; D059549:Anterior Cruciate Ligament Reconstruction; D053587:Arthrometry, Articular; D003198:Computer Simulation; D017076:Computer-Aided Design; D005269:Femur / Q000601:surgery; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008953:Models, Anatomic; D015588:Observer Variation; D016059:Range of Motion, Articular; D013314:Stress, Mechanical; D013710:Tendons / Q000637:transplantation; D013977:Tibia / Q000601:surgery; D014057:Tomography, X-Ray Computed; D014584:User-Computer Interface; D055815:Young Adult