title: Cervical spine reposition errors after cervical flexion and extension.
abstract: Upright head and neck position has been frequently applied as baseline for diagnosis of neck problems. However, the variance of the position after cervical motions has never been demonstrated. Thus, it is unclear if the baseline position varies evenly across the cervical joints. The purpose was to assess reposition errors of upright cervical spine.
  
  
  
  Cervical reposition errors were measured in twenty healthy subjects (6 females) using video-fluoroscopy. Two flexion movements were performed with a 20 s interval, the same was repeated for extension, with an interval of 5 min between flexion and extension movements. Cervical joint positions were assessed with anatomical landmarks and external markers in a Matlab program. Reposition errors were extracted in degrees (initial position minus reposition) as constant errors (CEs) and absolute errors (AEs).
  
  
  
  Twelve of twenty-eight CEs (7 joints times 4 repositions) exceeded the minimal detectable change (MDC), while all AEs exceeded the MDC. Averaged AEs across the cervical joints were larger after 5 min' intervals compared to 20 s intervals (p < 0.05).
  
  
  
  This is the first study to demonstrate single joint reposition errors of the cervical spine. The cervical spine returns to the upright positions with a 2° average absolute difference after cervical flexion and extension movements in healthy adults.
authors.affiliation: SMI, Department of Health and Science Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7D-3, 9220, Aalborg E, Denmark.|Department of Orthopedics, The Second Hospital of Jilin University, Ziqiang 218, Changchun, 130041, Jilin, People's Republic of China.
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.affiliation: SMI, Department of Health and Science Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7D-3, 9220, Aalborg E, Denmark.
authors.forename: René
authors.initials: R
authors.lastname: Lindstroem
authors.affiliation: Vejgaard Kiropraktisk Klinik, Aalborg, Denmark.
authors.forename: Niels Peter Bak
authors.initials: NP
authors.lastname: Carstens
authors.affiliation: Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health and Science Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej, 7D-39220, Aalborg, Denmark. tgn@hst.aau.dk.
authors.forename: Thomas
authors.initials: T
authors.lastname: Graven-Nielsen
mesh_terms: D000328:Adult; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D005471:Fluoroscopy; D064368:Healthy Volunteers; D006801:Humans; D007596:Joints / Q000000981:diagnostic imaging / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology; D009333:Neck / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D056888:Patient Positioning / Q000009:adverse effects*; D011187:Posture / Q000502:physiology*; D016059:Range of Motion, Articular; D013997:Time Factors; D055815:Young Adult
keywords: Cervical vertebrae; Flexion and extension; Fluoroscopy; Motion; Neck; Position sense; Repositioning; Spine