title: Talofibular interval changes after acute ankle sprain: a stress ultrasonography study of ankle laxity.
abstract: BACKGROUND
  Quantifying talocrural joint laxity after ankle sprain is problematic. Stress ultrasonography (US) can image the lateral talocrural joint and allow the measurement of the talofibular interval, which may suggest injury to the anterior talofibular ligament (ATFL). The acute talofibular interval changes after lateral ankle sprain are unknown.
  
  
  METHODS
  Twenty-five participants (9 male, 16 female; age 21.8 ± 3.2 y, height 167.8 ± 34.1 cm, mass 72.7 ± 13.8 kg) with 27 acute, lateral ankle injuries underwent bilateral stress US imaging at baseline (<7 d) and on the affected ankle at 3 wk and 6 wk from injury in 3 ankle conditions: neutral, anterior drawer, and inversion. Talofibular interval (mm) was measured using imaging software and self-reported function (activities of daily living [ADL] and sports) by the Foot and Ankle Ability Measure (FAAM).
  
  
  RESULTS
  The talofibular interval increased with anterior-drawer stress in the involved ankle (22.65 ± 3.75 mm; P = .017) over the uninvolved ankle (19.45 ± 2.35 mm; limb × position F1,26 = 4.9, P = .035) at baseline. Inversion stress also resulted in greater interval changes (23.41 ± 2.81 mm) than in the uninvolved ankles (21.13 ± 2.08 mm). A main effect for time was observed for inversion (F2,52 = 4.3, P = .019, 21.93 ± 2.24 mm) but not for anterior drawer (F2,52 = 3.1, P = .055, 21.18 ± 2.34 mm). A significant reduction in the talofibular interval took place between baseline and week 3 inversion measurements only (F1,26 = 5.6, P = .026). FAAM-ADL and sports results increased significantly from baseline to wk 3 (21.9 ± 16.2, P < .0001 and 23.8 ± 16.9, P < .0001) and from wk 3 to wk 6 (2.5 ± 4.4, P = .009 and 10.5 ± 13.2, P = .001).
  
  
  CONCLUSIONS
  Stress US methods identified increased talofibular interval changes suggestive of talocrural laxity and ATFL injury using anterior drawer and inversion stress that, despite significant improvements in self-reported function, only marginally improved during the 6 wk after ankle sprain. Stress US provides a safe, repeatable, and quantifiable method of measuring the talofibular interval and may augment manual stress examinations in acute ankle injuries.
authors.affiliation: US Army-Baylor University Doctoral Program in Physical Therapy, Fort Sam Houston, TX.
authors.forename: Theodore
authors.initials: T
authors.lastname: Croy
authors.forename: Susan
authors.initials: S
authors.lastname: Saliba
authors.forename: Ethan
authors.initials: E
authors.lastname: Saliba
authors.forename: Mark W
authors.initials: MW
authors.lastname: Anderson
authors.forename: Jay
authors.initials: J
authors.lastname: Hertel
mesh_terms: D000293:Adolescent; D000328:Adult; D016512:Ankle Injuries / Q000150:complications / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000209:etiology; D017844:Lateral Ligament, Ankle / Q000000981:diagnostic imaging* / Q000293:injuries; D008297:Male; D013180:Sprains and Strains / Q000150:complications / Q000000981:diagnostic imaging*; D013314:Stress, Mechanical; D013997:Time Factors; D014463:Ultrasonography; D055815:Young Adult