title: The correlation between craniovertebral angle, backpack weights, and disability due to neck pain in adolescents.
abstract: OBJECTIVE
  To investigate the responses of the craniovertebral (CV) angle to backpack loadings in adolescents with and without neck pain and to explore the relationships between CV angle, relative backpack weight, neck pain and disability.
  
  
  METHODS
  A cross-sectional single-blinded study was conducted on 60 adolescents (30 neck pain and 30 non-neck pain) aged from 13 to 18 years old. The verbal analog scale (VAS) and Chinese version of Northwick Park Neck Pain Questionnaire (NPQ) were used to assess neck pain severity and disability respectively. CV angle was measured in neutral and with backpack loadings of 5% to 30% of subject's body weight by using the Head Posture Spinal Curvature Instrument (HPSCI).
  
  
  RESULTS
  In both groups, CV angles gradually decreased with increment of backpack loadings and the amount of decreases became significant from 10% body weight onwards (P < 0.05). Although the changes of CV angles did not show any significant differences at any point of comparison between the groups, the neck pain group showed a clinically significant decrease of CV angle ( approximately 5 degrees ) at 10% relative loading whereas non-neck pain group did it at 15% relative loading. Change of CV angles did not show significant correlations with relative backpack weight, cervical pain and disability (P > 0.05).
  
  
  CONCLUSIONS
  Our findings suggested a safety limit of 10% relative backpack load for adolescents. The results showed the tendency that the ability of maintaining good head posture in response to backpack loadings by non-neck pain subjects might be better than those with neck pain.
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong.
authors.forename: C H
authors.initials: CH
authors.lastname: Cheung
authors.forename: S T
authors.initials: ST
authors.lastname: Shum
authors.forename: S F
authors.initials: SF
authors.lastname: Tang
authors.forename: P C
authors.initials: PC
authors.lastname: Yau
authors.forename: Thomas T W
authors.initials: TT
authors.lastname: Chiu
mesh_terms: D000293:Adolescent; D001877:Books; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D019547:Neck Pain / Q000503:physiopathology*; D011187:Posture; D016037:Single-Blind Method; D013121:Spinal Curvatures / Q000503:physiopathology*; D013131:Spine / Q000503:physiopathology*; D016474:Weight-Bearing / Q000502:physiology