title: The effect of a simulated knee joint effusion on postural control in healthy subjects.
abstract: OBJECTIVE
  To determine the effects of a simulated knee joint effusion on center of pressure (COP) path and mean power frequency (MPF) during standing.
  
  
  METHODS
  Quasi-experimental design.
  
  
  METHODS
  Sports injury research laboratory in a university setting.
  
  
  METHODS
  Twenty healthy volunteers, 10 of whom (age, 20.1+/-2.4y; height, 168.0+/-8.1cm; weight, 70.4+/-13.3kg) were assigned to an effusion group and 10 of whom (age, 25+/-3.8y; height, 169.4+/-8.9cm; weight, 74.7+/-7.7kg) were assigned to a control group.
  
  
  METHODS
  COP data were collected before and after a 60-mL injection of sterile saline into the knee joint space.
  
  
  METHODS
  COP path and mediolateral and anteroposterior MPF.
  
  
  RESULTS
  COP path decreased after the effusion (pre-effusion mean, 92.2+/-21.9cm; posteffusion mean, 77.27+/-23.0cm). No change was found within the control group for COP path (P>.05). No differences were detected before or after joint effusion when the MPF was examined (P>.05).
  
  
  CONCLUSIONS
  Possible explanations for the improved postural control after the effusion include additional somatosensory feedback, an augmented neural drive to the soleus, and/or increased capsular tension.
authors.affiliation: Sports Medicine / Atletic Training Research Laboratory, Department of Human Services, University of Virginia, Charlottesville, VA 22904-4407, USA. rmp5u@virginia.edu
authors.forename: Riann M
authors.initials: RM
authors.lastname: Palmieri
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Ingersoll
authors.forename: Mitchell L
authors.initials: ML
authors.lastname: Cordova
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Kinzey
authors.forename: Marcus B
authors.initials: MB
authors.lastname: Stone
authors.forename: B Andrew
authors.initials: BA
authors.lastname: Krause
mesh_terms: D000328:Adult; D000344:Afferent Pathways / Q000503:physiopathology; D016022:Case-Control Studies; D004525:Efferent Pathways / Q000503:physiopathology; D025461:Feedback, Physiological; D005260:Female; D005583:Fourier Analysis; D006181:H-Reflex; D006801:Humans; D006833:Hydrarthrosis / Q000503:physiopathology*; D007719:Knee Joint; D008297:Male; D008465:Mechanoreceptors / Q000503:physiopathology; D008954:Models, Biological; D004856:Postural Balance; D011187:Posture; D011434:Proprioception; D012815:Signal Processing, Computer-Assisted; D016474:Weight-Bearing