title: Effect of post-traumatic tibiotalar osteoarthritis on kinematics of the ankle joint complex.
abstract: BACKGROUND
  Knowledge of joint kinematics in the healthy and diseased joint may be useful if surgical techniques and joint replacement designs are to be improved. To date, little is known about the kinematics of the arthritic tibiotalar joint and its effect on the kinematics of the subtalar joint.
  
  
  METHODS
  Kinematics of the ankle joint complex (AJC) were measured in six patients with unilateral post-traumatic tibiotalar osteoarthritis in simulated heel strike, midstance and toe off weight bearing positions using magnetic resonance and dual fluoroscopic imaging techniques. The kinematic data obtained was compared to a normal cohort from a previous study.
  
  
  RESULTS
  From heel strike to midstance, the arthritic tibiotalar joint demonstrated 2.2 +/- 5.0 degrees of dorsiflexion while in the healthy controls the tibiotalar joint plantarflexed 9.1 +/- 5.3 degrees (p < 0.01). From midstance to toe off, the subtalar joint in the arthritic group dorsiflexed 3.3 +/- 4.1 degrees whereas in the control group the subtalar joint plantarflexed 8.5 +/- 2.9 degrees (p < 0.01). The subtalar joint in the arthritic group rotated externally 1.2 +/- 1.0 degrees and everted 3.3 +/- 6.1 degrees from midstance to toe off while in the control group 12.3 +/- 8.3 degrees of internal rotation and 10.7 +/- 3.8 degrees eversion (p < 0.01 and p < 0.01, respectively) was measured.
  
  
  CONCLUSIONS
  The current study suggests that during the stance phase of gait, subtalar joint motion in the sagittal, coronal, and transverse rotational planes tends to occur in an opposite direction in subjects with tibiotalar osteoarthritis when compared to normal ankle controls. This effectively represents a breakdown in the normal motion coupling seen in healthy ankle joints.
  
  
  CONCLUSIONS
  Knowledge of ankle kinematics of arthritic joints may be helpful when designing prostheses or in assessing the results of treatment interventions.
authors.affiliation: Massachusetts General Hospital, Orthopaedic Surgery, Boston, MA 02114, USA.
authors.forename: Michal
authors.initials: M
authors.lastname: Kozanek
authors.forename: Harry E
authors.initials: HE
authors.lastname: Rubash
authors.forename: Guoan
authors.initials: G
authors.lastname: Li
authors.forename: Richard J
authors.initials: RJ
authors.lastname: de Asla
mesh_terms: D000328:Adult; D000368:Aged; D016512:Ankle Injuries / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D000843:Ankle Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D001696:Biomechanical Phenomena / Q000502:physiology; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D013380:Subtalar Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D016896:Treatment Outcome; D016474:Weight-Bearing / Q000502:physiology