title: Biomechanical analysis of anterior cruciate ligament injury mechanisms: three-dimensional motion reconstruction from video sequences.
abstract: BACKGROUND
  Methods for analyzing the mechanisms of injuries in sports from video sequences of injury situations are so far limited to a simple visual inspection, which has shown poor accuracy.
  
  
  OBJECTIVE
  To investigate whether a new model-based image-matching technique could successfully be applied to estimate kinematic characteristics of three typical anterior cruciate ligament (ACL) injury situations.
  
  
  METHODS
  A four-camera basketballvideo, a three-camera European team handball video and a single-camera downhill skiing video were imported into the program Poser 4, where a skeleton model and a model of the surroundings were matched to the background image frame by frame. When the match was considered satisfactory, joint angles as well as velocity and acceleration of the center of mass were calculated using Matlab.
  
  
  RESULTS
  In the basketball and handball matchings, the skeleton and surrounding models were successfully matched to the background through all frames in all camera angles. Detailed time courses for joint kinematics and ground reaction force were obtained, while less information could be acquired from the single-view skiing accident.
  
  
  CONCLUSIONS
  The model-based image matching technique can be used to extract kinematic characteristics from videotapes of actual ACL injuries, and may provide valuable information on the mechanisms for ACL injuries in sports.
authors.affiliation: Oslo Sports Trauma Research Center, Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway. tron.krosshaug@nih.no
authors.forename: T
authors.initials: T
authors.lastname: Krosshaug
authors.forename: J R
authors.initials: JR
authors.lastname: Slauterbeck
authors.forename: L
authors.initials: L
authors.lastname: Engebretsen
authors.forename: R
authors.initials: R
authors.lastname: Bahr
mesh_terms: D000070598:Anterior Cruciate Ligament Injuries; D001490:Basketball / Q000293:injuries*; D001696:Biomechanical Phenomena; D006801:Humans; D007700:Kinetics; D008962:Models, Theoretical; D010865:Pilot Projects; D011187:Posture; D012307:Risk Factors; D012865:Skiing / Q000293:injuries*; D013997:Time Factors; D014741:Video Recording