title: In vivo kinematics of the tibiotalar joint after lateral ankle instability.
abstract: BACKGROUND
  Previous studies have suggested that injury to the anterior talofibular ligament (ATFL) may be linked to altered kinematics and the development of osteoarthritis of the ankle joint. However, the effects of ATFL injury on the in vivo kinematics of the ankle joint are unclear.
  
  
  OBJECTIVE
  Based on the orientation of the ATFL fibers, ATFL deficiency leads to increased anterior translation and increased internal rotation of the talus relative to the tibia.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  The ankles of 9 patients with unilateral ATFL injuries were compared as they stepped onto a level surface. Kinematic measurements were made as a function of increasing load. With use of magnetic resonance imaging and orthogonal fluoroscopy, the in vivo kinematics of the tibiotalar joint were measured in the ATFL-deficient and intact ankles of the same individuals.
  
  
  RESULTS
  A statistically significant increase in internal rotation, anterior translation, and superior translation of the talus was measured in ATFL-deficient ankles, as compared with the intact contralateral controls. For example, at 100% body weight, ATFL-deficient ankles demonstrated an increase of 0.9 +/- 0.5 mm in anterior translation (P = .008), an increase of 5.7 degrees +/- 3.6 degrees in internal rotation (P = .008), and a slight increase of 0.2 +/- 0.2 mm in the superior translation (P = .02) relative to the intact contralateral ankles.
  
  
  CONCLUSIONS
  Deficiency of the ATFL increases anterior translation, internal rotation, and superior translation of the talus.
  
  
  CONCLUSIONS
  Altered kinematics may contribute to the degenerative changes observed with chronic lateral ankle instability. These findings might help to explain the degenerative changes frequently observed on the medial talus in patients with chronic ATFL insufficiency and so provide a baseline for improving ankle ligament reconstructions aimed at restoring normal joint motion.
authors.affiliation: Division of Orthopaedic Surgery, Department of Radiology, Duke University, Durham, NC 27710, USA.
authors.forename: Adam M
authors.initials: AM
authors.lastname: Caputo
authors.forename: Jun Y
authors.initials: JY
authors.lastname: Lee
authors.forename: Chuck E
authors.initials: CE
authors.lastname: Spritzer
authors.forename: Mark E
authors.initials: ME
authors.lastname: Easley
authors.forename: James K
authors.initials: JK
authors.lastname: DeOrio
authors.forename: James A
authors.initials: JA
authors.lastname: Nunley
authors.forename: Louis E
authors.initials: LE
authors.lastname: DeFrate
mesh_terms: D000328:Adult; D016512:Ankle Injuries / Q000503:physiopathology*; D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008023:Ligaments, Articular / Q000293:injuries / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012399:Rotation; D013628:Talus / Q000503:physiopathology*; D055815:Young Adult