title: Examining Ankle-Joint Laxity Using 2 Knee Positions and With Simulated Muscle Guarding.
abstract: BACKGROUND
  Several factors affect the reliability of the anterior drawer and talar tilt tests, including the individual clinician's experience and skill, ankle and knee positioning, and muscle guarding.
  
  
  OBJECTIVE
  To compare gastrocnemius activity during the measurement of ankle-complex motion at different knee positions, and secondarily, to compare ankle-complex motion during a simulated trial of muscle guarding.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Research laboratory.
  
  
  METHODS
  Thirty-three participants aged 20.2 ± 1.7 years were tested.
  
  
  METHODS
  The ankle was loaded under 2 test conditions (relaxed, simulated muscle guarding) at 2 knee positions (0°, 90° of flexion) while gastrocnemius electromyography (EMG) activity was recorded.
  
  
  METHODS
  Anterior displacement (mm), inversion-eversion motion (°), and peak EMG amplitude values of the gastrocnemius (μV).
  
  
  RESULTS
  Anterior displacement did not differ between the positions of 0° and 90° of knee flexion (P = .193). Inversion-eversion motion was greater at 0° of knee flexion compared with 90° (P < .001). Additionally, peak EMG amplitude of the gastrocnemius was not different between 0° and 90° of knee flexion during anterior displacement (P = .101). As expected, the simulated muscle-guarding trial reduced anterior displacement compared with the relaxed condition (0° of knee flexion, P = .008; 90° of knee flexion, P = .016) and reduced inversion-eversion motion (0° of knee flexion, P = .03; 90° of knee flexion, P < .001).
  
  
  CONCLUSIONS
  In a relaxed state, the gastrocnemius muscle did not appear to affect anterior ankle laxity at the 2 most common knee positions for anterior drawer testing; however, talar tilt testing may be best performed with the knee in 0° of knee flexion. Finally, our outcomes from the simulated muscle-guarding condition suggest that clinicians should use caution and be aware of reduced perceived laxity when performing these clinical examination techniques immediately postinjury.
authors.affiliation: University of Delaware, Newark.
authors.forename: Shawn
authors.initials: S
authors.lastname: Hanlon
authors.affiliation: University of Delaware, Newark.
authors.forename: Jaclyn
authors.initials: J
authors.lastname: Caccese
authors.affiliation: University of Delaware, Newark.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Knight
authors.affiliation: University of Delaware, Newark.
authors.forename: Charles Buz
authors.initials: CB
authors.lastname: Swanik
authors.affiliation: University of Delaware, Newark.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Kaminski
mesh_terms: D016512:Ankle Injuries / Q000175:diagnosis; D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis*; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010808:Physical Examination / Q000379:methods*; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D013180:Sprains and Strains / Q000175:diagnosis; D055815:Young Adult
keywords: ankle arthrometer; anterior drawer; electromyography; manual examination; talar tilt