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Cervical spine joint loading with neck flexion.
Ergonomics. 2020 Jan; 63(1):101-108.E

Abstract

Cervical spine flexion is a common posture for those using computers, tablets, and smartphones; the latter being dubbed 'text-neck' in recent years. Coincidentally, flexion has been flagged as a significant mechanical risk factor for the development of chronic neck pain. Unfortunately, few modelling endeavours have attempted to quantify the intervertebral joint loads throughout the cervical spine in flexion, while still accounting for muscular activation. Eight healthy male subjects undertook five trials beginning in a neutral posture, flexed to 45 degrees, and returned to a neutral posture. 3 D head-trunk angles and surface electromyography from 10 neck muscles (5 bilaterally) were used as inputs into an inverse dynamic cervical spine model based on a 50th percentile male to compute the compression and anteroposterior (AP) shear forces for this flexion task. In general, compression increases cranially to caudally throughout the cervical spine, but levels off at the C5-C6 level. Conversely, in a neutral posture, there is a constant 18 N of anterior shear at each joint level. Compression increased twofold throughout the cervical spine with flexion, whereas anterior shear increased fourfold in the upper cervical spine and dramatically decreased caudally. The dramatic change in joint kinetics provides some mechanical evidence for the role of posture and interplay with muscle activity in the development of chronic neck pain. Results from this study can reinforce the need for appropriate workstation and monitor configurations and support the increased loading hypothesised to occur in 'text neck' postures. Practitioner summary: The purpose of this investigation was to quantify the compression and shear forces in the neck in 45 degrees of flexion compared to neutral. Flexion increased compression throughout the cervical spine 1.6-fold compared to a neutral posture. In the upper cervical spine, AP-shear increased four-fold compared to neutral. Abbreviation: AP: anteroposterior.

Links

Publisher Full Text (DOI)

Authors+Show Affiliations

Barrett JM
Department of Kinesiology, University of Waterloo, Waterloo, Canada.
McKinnon C
Department of Kinesiology, University of Waterloo, Waterloo, Canada.
Callaghan JP
Department of Kinesiology, University of Waterloo, Waterloo, Canada.

MeSH

Biomechanical PhenomenaCervical VertebraeElectromyographyHealthy VolunteersHumansMaleNeck MusclesPostureRange of Motion, ArticularYoung Adult

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31594480

Clinical Trial Links

Isometric Exercises With and Without Pressure Biofeedback in Computer Users With Cervical Spine Overload

Citation

Barrett, Jeff Matthew, et al. "Cervical Spine Joint Loading With Neck Flexion." Ergonomics, vol. 63, no. 1, 2020, pp. 101-108.
Barrett JM, McKinnon C, Callaghan JP. Cervical spine joint loading with neck flexion. Ergonomics. 2020;63(1):101-108.
Barrett, J. M., McKinnon, C., & Callaghan, J. P. (2020). Cervical spine joint loading with neck flexion. Ergonomics, 63(1), 101-108. https://doi.org/10.1080/00140139.2019.1677944
Barrett JM, McKinnon C, Callaghan JP. Cervical Spine Joint Loading With Neck Flexion. Ergonomics. 2020;63(1):101-108. PubMed PMID: 31594480.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Cervical spine joint loading with neck flexion. AU - Barrett,Jeff Matthew, AU - McKinnon,Colin, AU - Callaghan,Jack P, Y1 - 2019/10/15/ PY - 2019/10/9/pubmed PY - 2020/6/13/medline PY - 2019/10/10/entrez KW - Flexion KW - compression KW - neck KW - shear KW - text neck SP - 101 EP - 108 JF - Ergonomics JO - Ergonomics VL - 63 IS - 1 N2 - Cervical spine flexion is a common posture for those using computers, tablets, and smartphones; the latter being dubbed 'text-neck' in recent years. Coincidentally, flexion has been flagged as a significant mechanical risk factor for the development of chronic neck pain. Unfortunately, few modelling endeavours have attempted to quantify the intervertebral joint loads throughout the cervical spine in flexion, while still accounting for muscular activation. Eight healthy male subjects undertook five trials beginning in a neutral posture, flexed to 45 degrees, and returned to a neutral posture. 3 D head-trunk angles and surface electromyography from 10 neck muscles (5 bilaterally) were used as inputs into an inverse dynamic cervical spine model based on a 50th percentile male to compute the compression and anteroposterior (AP) shear forces for this flexion task. In general, compression increases cranially to caudally throughout the cervical spine, but levels off at the C5-C6 level. Conversely, in a neutral posture, there is a constant 18 N of anterior shear at each joint level. Compression increased twofold throughout the cervical spine with flexion, whereas anterior shear increased fourfold in the upper cervical spine and dramatically decreased caudally. The dramatic change in joint kinetics provides some mechanical evidence for the role of posture and interplay with muscle activity in the development of chronic neck pain. Results from this study can reinforce the need for appropriate workstation and monitor configurations and support the increased loading hypothesised to occur in 'text neck' postures. Practitioner summary: The purpose of this investigation was to quantify the compression and shear forces in the neck in 45 degrees of flexion compared to neutral. Flexion increased compression throughout the cervical spine 1.6-fold compared to a neutral posture. In the upper cervical spine, AP-shear increased four-fold compared to neutral. Abbreviation: AP: anteroposterior. SN - 1366-5847 UR - https://www.unboundmedicine.com/medline/citation/31594480/Cervical_spine_joint_loading_with_neck_flexion_ DB - PRIME DP - Unbound Medicine ER -