title: Photographic measurement of head and cervical posture when viewing mobile phone: a pilot study.
abstract: OBJECTIVE
  With the dramatic growth of mobile phone usage, concerns have been raised with regard to the adverse health effects of mobile phone on spinal posture. The aim of this study was to determine the head and cervical postures by photogrammetry when viewing the mobile phone screen, compared with those in neutral standing posture.
  
  
  METHODS
  A total of 186 subjects (81 females and 105 males) aged from 17 to 31 years old participated in this study. Subjects were instructed to stand neutrally and using mobile phone as in daily life. Using a photographic method, the sagittal head and cervical postures were assessed by head tilt angle, neck tilt angle, forward head shift and gaze angle.
  
  
  RESULTS
  The photographic method showed a high intra-rater and inter-rater reliability in measuring the sagittal posture of cervical spine and gaze angle (ICCs ranged from 0.80 to 0.99). When looking at mobile phone, the head tilt angle significantly increased (from 74.55° to 95.22°, p = 0.000) and the neck angle decreased (from 54.68° to 38.77°, p = 0.000). The forward head posture was also confirmed by the significantly increased head shift (from 10.90 to 13.85 cm, p = 0.000). The posture assumed in mobile phone use was significantly correlated with neutral posture (p < 0.05). Males displayed a more forward head posture than females (p < 0.05). The head tilt angle was positively correlated with the gaze angle (r = 0.616, p = 0.000), while the neck tilt angle was negatively correlated with the gaze angle (r = -0.628, p = 0.000).
  
  
  CONCLUSIONS
  Photogrammetry is a reliable, quantitative method to evaluate the head and cervical posture during mobile phone use. Compared to neutral standing, subjects display a more forward head posture when viewing the mobile phone screen, which is correlated with neutral posture, gaze angle and gender. Future studies will be needed to investigate a dose-response relationship between mobile phone use and assumed posture.
authors.affiliation: Department of Orthopedics, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 200072, Shanghai, People's Republic of China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Guan
authors.affiliation: Department of Orthopedics, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 200072, Shanghai, People's Republic of China.
authors.forename: Guoxin
authors.initials: G
authors.lastname: Fan
authors.affiliation: Department of Orthopedics, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 200072, Shanghai, People's Republic of China.
authors.forename: Xinbo
authors.initials: X
authors.lastname: Wu
authors.affiliation: Tongji University School of Medicine, 200092, Shanghai, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zeng
authors.affiliation: Department of Orthopedics, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 200072, Shanghai, People's Republic of China.
authors.forename: Hang
authors.initials: H
authors.lastname: Su
authors.affiliation: Department of Orthopedics, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 200072, Shanghai, People's Republic of China.
authors.forename: Guangfei
authors.initials: G
authors.lastname: Gu
authors.affiliation: Department of Orthopedics, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 200072, Shanghai, People's Republic of China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Department of Orthopedics, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 200072, Shanghai, People's Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Gu
authors.affiliation: Department of Orthopedics, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 200072, Shanghai, People's Republic of China.
authors.forename: Hailong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 200072, Shanghai, People's Republic of China. tjspinecenter@163.com.
authors.forename: Shisheng
authors.initials: S
authors.lastname: He
mesh_terms: D000293:Adolescent; D000328:Adult; D040421:Cell Phone; D002574:Cervical Vertebrae / Q000502:physiology*; D005260:Female; D006257:Head / Q000502:physiology*; D006801:Humans; D008297:Male; D009333:Neck / Q000502:physiology*; D010780:Photogrammetry; D010781:Photography; D010865:Pilot Projects; D011187:Posture / Q000502:physiology*; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Cervical spine; Forward head posture; Mobile phone; Photogrammetry