title: Navigated knee kinematics after cutting of the ACL and its secondary restraint.
abstract: OBJECTIVE
  The purpose of this study is to evaluate the kinematics changes of the knee after cutting of the ACL with or without injury of the anterolateral structures.
  
  
  METHODS
  In this study, the role of the ACL and one of the secondary restraints in controlling knee stability using a navigation system was evaluated. The kinematics of the knee was evaluated in different conditions of instability: ACL intact, after dissection of the posterolateral (PL) bundle, after dissection of the anteromedial (AM) bundle, and after lesion of the lateral capsular ligament (LCL). Anterior tibial translation and rotation were measured with a computer navigation system in 10 fresh-frozen cadaveric knees by use of a manual maximum load. Anterior translation was evaluated at 30°, 60°, and 90° of flexion; rotation at 0°, 15°, 30°, 45°, 60°, and 90°.
  
  
  RESULTS
  Cutting the PL bundle does not increase anterior translation and rotation of the knee. Cutting the AM bundle significantly increased the anteroposterior (AP) translation at 30° and 60° (P = 0.01), but does not increase rotation of the knee. Cutting the LCL increased anterior translation at 60° (P = 0.04) and rotation at 30°, 45°, and 60° (P = 0.03).
  
  
  CONCLUSIONS
  Within the testing conditions of this study, the PL bundle does not affect anterior translation and rotation of the knee; the AM bundle is the primary restraint of the anterior translation but does not affect rotation of the knee while the lesion of the LCL increases tibial rotation and could be related to the pivot shift phenomenon, so it is more correct and biomechanical valid to assess and repair the associated lesion of the antero-lateral structure of the knee at the time of ACL surgery.
authors.affiliation: Orthopaedic Unit and Kirk Kilgour Sports Injury Center, II School of Medicine, Sant'Andrea Hospital, Sapienza University of Rome, Rome, Italy. edoardo.monaco@tin.it
authors.forename: E
authors.initials: E
authors.lastname: Monaco
authors.forename: A
authors.initials: A
authors.lastname: Ferretti
authors.forename: L
authors.initials: L
authors.lastname: Labianca
authors.forename: B
authors.initials: B
authors.lastname: Maestri
authors.forename: A
authors.initials: A
authors.lastname: Speranza
authors.forename: M J
authors.initials: MJ
authors.lastname: Kelly
authors.forename: C
authors.initials: C
authors.lastname: D'Arrigo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016118:Anterior Cruciate Ligament / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D007718:Knee Injuries / Q000503:physiopathology* / Q000601:surgery; D008023:Ligaments, Articular / Q000293:injuries* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular