title: Dancers with achilles tendinopathy demonstrate altered lower extremity takeoff kinematics.
abstract: METHODS
  Controlled laboratory study using a cross-sectional design.
  
  
  OBJECTIVE
  To analyze lower extremity kinematics during takeoff of a "saut de chat" (leap) in dancers with and without a history of Achilles tendinopathy (AT). We hypothesized that dancers with AT would demonstrate different kinematic strategies compared to dancers without pathology, and that these differences would be prominent in the transverse and frontal planes.
  
  
  BACKGROUND
  AT is a common injury experienced by dancers. Dance leaps such as the saut de chat place a large demand on the Achilles tendon.
  
  
  METHODS
  Sixteen female dancers with and without a history of AT (mean ± SD age, 18.8 ± 1.2 years) participated. Three-dimensional kinematics at the hip, knee, and ankle were quantified for the takeoff of the saut de chat, using a motion analysis system. A force platform was used to determine braking and push-off phases of takeoff. Peak sagittal, frontal, and transverse plane joint positions during the braking and push-off phases of the takeoff were examined statistically. Independent samples t tests were used to evaluate group differences (α = .05).
  
  
  RESULTS
  The dancers in the tendinopathy group demonstrated significantly higher peak hip adduction during the braking phase of takeoff (mean ± SD, 13.5° ± 6.1° versus 7.7° ± 4.2°; P = .046). During the push-off phase, dancers with AT demonstrated significantly more internal rotation at the knee (13.2° ± 5.2° versus 6.9° ± 4.9°; P = .024).
  
  
  CONCLUSIONS
  Dancers with AT demonstrate increased peak transverse and frontal plane kinematics when performing the takeoff of a saut de chat. These larger displacements may be either causative or compensatory factors in the development of AT.
authors.affiliation: University of Southern California, Division of Biokinesiology and Physical Therapy, Los Angeles, CA 90089-9006, USA. kulig@usc.edu
authors.forename: Kornelia
authors.initials: K
authors.lastname: Kulig
authors.forename: Janice K
authors.initials: JK
authors.lastname: Loudon
authors.forename: John M
authors.initials: JM
authors.lastname: Popovich
authors.forename: Christine D
authors.initials: CD
authors.lastname: Pollard
authors.forename: Brooke R
authors.initials: BR
authors.lastname: Winder
mesh_terms: D000125:Achilles Tendon / Q000503:physiopathology*; D000293:Adolescent; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D003615:Dancing / Q000502:physiology*; D005260:Female; D006801:Humans; D007866:Leg / Q000503:physiopathology*; D052256:Tendinopathy / Q000503:physiopathology*; D055815:Young Adult