title: Application of robotic technology in biomechanics to study joint laxity.
abstract: OBJECTIVE
  To evaluate whether in vitro joint testing using a robot with six degrees of freedom is useful for evaluating changes in joint laxity as a result of chronic osteoarthritis (OA).
  
  
  METHODS
  Repeated measures.
  
  
  METHODS
  Broyden's method of solving nonlinear systems of equations drove a hybrid method of load and position robotic control. Sheep stifles (knee joints) were loaded between 3 Nm of internal load through to 3 Nm of external load in 1 Nm increments. Kinematic and morphologic data from five healthy ovine stifles were compared to the chronic OA effects in four surgically destabilized stifles.
  
  
  RESULTS
  Stifles with chronic OA showed increases in stiffness while range of motion decreased. Gross morphologic changes included osteophytes and cartilage fibrillation.
  
  
  CONCLUSIONS
  Robotic testing proved useful for evaluating changes in joint mechanics as a result of chronic OA. We observed morphological changes and associated increases in joint stiffness and decreased laxity.
authors.affiliation: Department of Human Health and Nutritional Science, University of Guelph, 50 Stone Rd. West, Guelph, Ontario, N1G 2W1, Canada.
authors.forename: B
authors.initials: B
authors.lastname: Mangan
authors.forename: M B
authors.initials: MB
authors.lastname: Hurtig
authors.forename: J P
authors.initials: JP
authors.lastname: Dickey
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D020811:Biomedical Technology / Q000295:instrumentation*; D002908:Chronic Disease; D005260:Female; D007593:Joint Instability / Q000503:physiopathology*; D008954:Models, Biological; D010003:Osteoarthritis / Q000503:physiopathology; D016059:Range of Motion, Articular; D012371:Robotics / Q000295:instrumentation*; D012756:Sheep; D013264:Stifle / Q000502:physiology / Q000503:physiopathology