title: Intrasession and intersession reliability of postural control in participants with and without nonspecific low back pain using the Biodex Balance System.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the reliability of the Biodex Balance System (BBS) (Biodex Medical Systems, Shirley, NY) in chronic low back pain (CLBP) patients and healthy individuals in various conditions of postural and cognitive difficulty.
  
  
  METHODS
  In this methodological study, using the BBS, dynamic balance of 15 CLBP patients and 15 healthy matched individuals was assessed during bilateral stance in combined conditions of visual feedback (eyes open and eyes closed) and platform stability (levels 5 and 3), either isolated or concurrent with performing cognitive task (auditory Stroop task). The Overall stability index, anterior-posterior stability index, and medial-lateral stability index, provided by BBS as measures of postural performance, were recorded. Intraclass correlation coefficient (ICC), standard error of measurement, and coefficient of variation were used to determine intersession and intrasession reliability of postural and cognitive measures.
  
  
  RESULTS
  Biodex Balance System stability indices were more reliable in the CLBP (compared with healthy) group. The intersession ICCs in CLBP group for anterior-posterior stability index ranged from 0.60 to 0.88, for medial-lateral stability index from 0.64 to 0.94, and for OASI from 0.63 to 0.91. The intersession ICCs in healthy group for anterior-posterior stability index ranged from 0.42 to 0.86, for medial-lateral stability index from 0.56 to 0.89, and for OASI from 0.54 to 0.84. Biodex Balance System stability indices were more reliable in eyes-closed (compared with eyes-open) condition and platform stability level 5 (compared with level 3).
  
  
  CONCLUSIONS
  Biodex Balance System stability indices appear to be reliable measures of postural control in the CLBP patients especially in more challenging conditions, such as when standing with eyes closed.
authors.affiliation: Physiotherapy Department of University of Social Welfare & Rehabilitation Sciences, Tehran, Iran.
authors.forename: Shiva
authors.initials: S
authors.lastname: Sherafat
authors.forename: Mahyar
authors.initials: M
authors.lastname: Salavati
authors.forename: Ismail
authors.initials: I
authors.lastname: Ebrahimi Takamjani
authors.forename: Behnam
authors.initials: B
authors.lastname: Akhbari
authors.forename: Shahrzad
authors.initials: S
authors.lastname: Mohammadirad
authors.forename: Masood
authors.initials: M
authors.lastname: Mazaheri
authors.forename: Hossein
authors.initials: H
authors.lastname: Negahban
mesh_terms: D059350:Chronic Pain / Q000503:physiopathology*; D019937:Diagnostic Techniques and Procedures; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology*; D008297:Male; D004856:Postural Balance; D015203:Reproducibility of Results; D055815:Young Adult