title: Direction-Specific Impairments in Cervical Range of Motion in Women with Chronic Neck Pain: Influence of Head Posture and Gravitationally Induced Torque.
abstract: BACKGROUND
  Cervical range of motion (ROM) is commonly assessed in clinical practice and research. In a previous study we decomposed active cervical sagittal ROM into contributions from lower and upper levels of the cervical spine and found level- and direction-specific impairments in women with chronic non-specific neck pain. The present study aimed to validate these results and investigate if the specific impairments can be explained by the neutral posture (defining zero flexion/extension) or a movement strategy to avoid large gravitationally induced torques on the cervical spine.
  
  
  METHODS
  Kinematics of the head and thorax was assessed in sitting during maximal sagittal cervical flexion/extension (high torque condition) and maximal protraction (low torque condition) in 120 women with chronic non-specific neck pain and 40 controls. We derived the lower and upper cervical angles, and the head centre of mass (HCM), from a 3-segment kinematic model. Neutral head posture was assessed using a standardized procedure.
  
  
  RESULTS
  Previous findings of level- and direction-specific impairments in neck pain were confirmed. Neutral head posture was equal between groups and did not explain the direction-specific impairments. The relative magnitude of group difference in HCM migration did not differ between high and low torques conditions, lending no support for our hypothesis that impairments in sagittal ROM are due to torque avoidance behaviour.
  
  
  CONCLUSIONS
  The direction- and level-specific impairments in cervical sagittal ROM can be generalised to the population of women with non-specific neck pain. Further research is necessary to clarify if torque avoidance behaviour can explain the impairments.
authors.affiliation: Centre for Musculoskeletal Research, University of Gävle, Umeå, Sweden.|Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå, Sweden.
authors.forename: Thomas
authors.identifier: http://orcid.org/0000-0002-2804-3200
authors.initials: T
authors.lastname: Rudolfsson
authors.affiliation: Centre for Musculoskeletal Research, University of Gävle, Umeå, Sweden.|Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Björklund
authors.affiliation: Centre for Musculoskeletal Research, University of Gävle, Umeå, Sweden.|Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå, Sweden.
authors.forename: Åsa
authors.initials: Å
authors.lastname: Svedmark
authors.affiliation: Centre for Musculoskeletal Research, University of Gävle, Umeå, Sweden.
authors.forename: Divya
authors.initials: D
authors.lastname: Srinivasan
authors.affiliation: Centre for Musculoskeletal Research, University of Gävle, Umeå, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Djupsjöbacka
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena / Q000502:physiology; D002574:Cervical Vertebrae / Q000503:physiopathology*; D059350:Chronic Pain / Q000503:physiopathology*; D005260:Female; D006112:Gravitation; D006257:Head / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D009333:Neck / Q000502:physiology; D019547:Neck Pain / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D019415:Torque; D055815:Young Adult