title: In vivo kinematics of anterior cruciate ligament deficient knees during pivot and squat activities.
abstract: BACKGROUND
  Knee kinematics during pivoting activities are not well studied, but might provide insight critical to understanding the pathology of the anterior cruciate ligament deficient knee. The purpose of this study was to compare in vivo kinematics during weight bearing pivot and squat activities in patients with unilateral anterior cruciate ligament deficient knees, and to contrast those kinematics with the uninjured contralateral knees.
  
  
  METHODS
  Eight unilateral anterior cruciate ligament deficient patients with a mean age of 41 (SD 7) years were enrolled. Anterior cruciate injury was confirmed by positive Lachman test and MRI. Lateral fluoroscopic images of pivot and squat activities were recorded for both anterior cruciate ligament deficient and contralateral knees. Three-dimensional tibiofemoral kinematics and centers of rotation for each knee were determined using 3D-2D model registration techniques.
  
  
  RESULTS
  During pivoting, the tibia of the anterior cruciate ligament deficient knee was significantly more anterior than the contralateral knee during tibial neutral to internal rotation. The pivot activity showed lateral centers of rotation in both anterior cruciate ligament deficient and contralateral knees while squatting showed medial centers of rotation.
  
  
  CONCLUSIONS
  This dynamic method might be useful to objectively characterize restoration of dynamic function in knees with various types of anterior cruciate ligament reconstructions. These results also indicate kinematics during squatting type activities cannot be extrapolated to predict knee kinematics during pivoting types of activities.
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Florida, 330 MAE-A P.O. Box 116250, Gainesville, FL 32611-6250, USA. y-satoshi@mvb.biglobe.ne.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamaguchi
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Gamada
authors.forename: Takahisa
authors.initials: T
authors.lastname: Sasho
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kato
authors.forename: Masaki
authors.initials: M
authors.lastname: Sonoda
authors.forename: Scott A
authors.initials: SA
authors.lastname: Banks
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005080:Exercise Test; D005260:Female; D005269:Femur / Q000503:physiopathology; D006801:Humans; D021621:Imaging, Three-Dimensional; D007717:Knee / Q000503:physiopathology; D007718:Knee Injuries / Q000503:physiopathology*; D008297:Male; D012399:Rotation; D013977:Tibia / Q000503:physiopathology; D016474:Weight-Bearing