title: Differences in lateral ankle laxity measured via stress ultrasonography in individuals with chronic ankle instability, ankle sprain copers, and healthy individuals.
abstract: METHODS
  Cross-sectional.
  
  
  OBJECTIVE
  To use stress ultrasonography to measure the change in anterior talofibular ligament length during the simulated anterior drawer and ankle inversion stress tests.
  
  
  BACKGROUND
  In approximately 30% of individuals, ankle sprains may eventually develop into chronic ankle instability (CAI) with recurrent symptoms. Individuals with CAI and those who have a history of ankle sprain (greater than 1 year prior) without chronic instability (copers) may or may not have mechanical laxity.
  
  
  METHODS
  Sixty subjects (n=60 ankles) were divided into 3 groups: 1) Control subjects without ankle injury history (n=20; mean ± SD age; 24.8 ± 4.8 years; height, 173.7 ± 9.4 cm; weight, 77.2 ± 19.5 kg), ankle sprain copers (n=20; 22.3 ± 2.9 years; 172.8 ± 11.3 cm; 72.4 ± 14.3 kg), and subjects with CAI (n=20; 23.5 ± 4.2 years; 174.6 ± 9.6 cm; 74.8 ± 17.3 kg). Ligament length change with the anterior drawer and end range ankle inversion was calculated from ultrasound images. The Foot and Ankle Ability Measure (FAAM) was used to quantify self-reported function on activities-of-daily living (ADL) and sports.
  
  
  RESULTS
  The anterior drawer test resulted in length changes that were greater (F₂,₅₇=6.2, P=.004) in the CAI (mean ± SD length change, 15.6 ± 15.1%, P=.006) and the coper groups (14.0 ± 15.9%, P=.016) compared to the control group (1.3 ± 10.7%); however the length change for the CAI and coper groups were not different (P=.93). Ankle inversion similarly resulted in greater ligament length change (F₂,₅₇=6.5, P=.003) in the CAI (25.3 ± 15.5%, P=.003) and coper groups (20.2 ± 19.6%, P=.039) compared to the control group (7.4 ± 12.9%); with no difference in length change between the copers and CAI groups (P=.59). The CAI group had a lower score on the FAAM-ADL (87.4 ± 13.4%) and FAAM-Sports (74.2 ± 17.8%) when compared to the control (98.8 ± 2.9% and 98.9 ± 3.1%, P<.0001) and coper groups (99.4 ± 1.8% and 94.6 ± 8.8%, P<.0001).
  
  
  CONCLUSIONS
  Stress ultrasonography identified greater length changes of the anterior talofibular ligament in both the coper and CAI groups compared to the control group. Only subjects with CAI had reductions in self-reported function.
authors.affiliation: US Army-Baylor University Doctoral Program in Physical Therapy, Fort Sam Houston, TX 78234, USA. tcroypt@gmail.com
authors.forename: Theodore
authors.initials: T
authors.lastname: Croy
authors.forename: Susan A
authors.initials: SA
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: D000328:Adult; D016512:Ankle Injuries / Q000503:physiopathology; D000843:Ankle Joint / Q000000981:diagnostic imaging*; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging*; D017844:Lateral Ligament, Ankle / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D013180:Sprains and Strains / Q000000981:diagnostic imaging*; D014463:Ultrasonography; D055815:Young Adult