title: Lower extremity jumping mechanics of female athletes with and without patellofemoral pain before and after exertion.
abstract: BACKGROUND
  Patellofemoral pain is especially common among female athletes and is traditionally associated with lower extremity mechanics thought to increase retropatellar stress. These detrimental mechanics may increase with exertion.
  
  
  OBJECTIVE
  Differences in lower extremity mechanics during single-legged jumps between female athletes with and without patellofemoral pain will increase after exertion.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Twenty women with patellofemoral pain and 20 healthy female controls participated in a functional lower extremity exertion protocol of repetitive single-legged jumps. Pain, exertion, hip and trunk strength, and 3-dimensional lower extremity joint mechanics were recorded at the beginning and end of the protocol.
  
  
  RESULTS
  The patellofemoral pain group reported increased pain at the conclusion of the protocol. However, all subjects terminated the protocol due to complaints of fatigue. Mean strength measurements for the patellofemoral pain group were 24% lower for lateral trunk flexion (P = .06), 13% lower for hip abduction (P = .09), and 14% lower for hip external rotation (P = .03) than for controls. Subjects with patellofemoral pain demonstrated greater contralateral pelvic drop at the end of the exertion protocol compared with the control group (P = .003). Group differences in lower extremity mechanics, including increased hip adduction angle, hip flexion angle, hip abduction angular impulse, and decreased hip internal rotation angles, were observed among women with patellofemoral pain throughout the exertion protocol. These group differences were consistent despite increased pain for the patellofemoral pain group after exertion. Both groups demonstrated decreased jump height, hip flexion and internal rotation, knee flexion, and hip extension impulse at the end of the protocol.
  
  
  CONCLUSIONS
  Women with patellofemoral pain demonstrated lower extremity mechanics that differed from the healthy control group during single-legged jumping, particularly at the hip. These differences do not appear to vary with exertion level or pain among patellofemoral pain subjects during single-legged jumps.
  
  
  CONCLUSIONS
  Lower extremity jumping mechanics appear to be consistently different among women with patellofemoral pain. Conservative treatment programs that include kinematic retraining as well as hip and trunk strengthening may improve patient outcomes and prevent recurrence of this common orthopaedic condition.
authors.affiliation: University of Wisconsin-La Crosse, Physical Therapy Program, 4054 Health Science Center, 1725 State Street, La Crosse, WI 54601, USA. willson.john@uwlax.edu
authors.forename: John D
authors.initials: JD
authors.lastname: Willson
authors.forename: Stuart
authors.initials: S
authors.lastname: Binder-Macleod
authors.forename: Irene S
authors.initials: IS
authors.lastname: Davis
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005221:Fatigue; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D046788:Patellofemoral Pain Syndrome / Q000503:physiopathology*