title: Passive mechanical properties of gastrocnemius muscles of people with ankle contracture after stroke.
abstract: OBJECTIVE
  To investigate the mechanisms of contracture after stroke by comparing passive mechanical properties of gastrocnemius muscle-tendon units, muscle fascicles, and tendons in people with ankle contracture after stroke with control participants.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Laboratory in a research institution.
  
  
  METHODS
  A convenience sample of people with ankle contracture after stroke (n=20) and able-bodied control subjects (n=30).
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Stiffness and lengths of gastrocnemius muscle-tendon units, lengths of muscle fascicles, and tendons at specific tensions.
  
  
  RESULTS
  At a tension of 100N, the gastrocnemius muscle-tendon unit was significantly shorter in participants with stroke (mean, 436mm) than in able-bodied control participants (mean, 444mm; difference, 8mm; 95% confidence interval [CI], 0.2-15mm; P=.04). Muscle fascicles were also shorter in the stroke group (mean, 44mm) than in the control group (mean, 50mm; difference, 6mm; 95% CI, 1-12mm; P=.03). There were no significant differences between groups in the mean stiffness or length of the muscle-tendon units and fascicles at low tension, or in the mean length of the tendons at any tension.
  
  
  CONCLUSIONS
  People with ankle contracture after stroke have shorter gastrocnemius muscle-tendon units and muscle fascicles than control participants at high tension. This difference is not apparent at low tension.
authors.affiliation: George Institute for Global Health, Sydney, NSW, Australia.
authors.forename: Li Khim
authors.initials: LK
authors.lastname: Kwah
authors.forename: Robert D
authors.initials: RD
authors.lastname: Herbert
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Harvey
authors.forename: Joanna
authors.initials: J
authors.lastname: Diong
authors.forename: Jillian L
authors.initials: JL
authors.lastname: Clarke
authors.forename: Joshua H
authors.initials: JH
authors.lastname: Martin
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Clarke
authors.forename: Phu D
authors.initials: PD
authors.lastname: Hoang
authors.forename: Lynne E
authors.initials: LE
authors.lastname: Bilston
authors.forename: Simon C
authors.initials: SC
authors.lastname: Gandevia
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000843:Ankle Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D003286:Contracture / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016013:Likelihood Functions; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000000981:diagnostic imaging; D018482:Muscle, Skeletal; D012016:Reference Values; D012720:Severity of Illness Index; D013314:Stress, Mechanical; D020521:Stroke / Q000150:complications; D000071939:Stroke Rehabilitation; D019415:Torque; D018608:Ultrasonography, Doppler