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Posture and Helmet Configuration Effects on Joint Reaction Loads in the Middle Cervical Spine.
Aerosp Med Hum Perform. 2022 May 01; 93(5):458-466.AM

Abstract

INTRODUCTION: Between 43 and 97% of helicopter pilots in the Canadian Armed Forces report neck pain. Potential contributing factors include the weight of their helmet, night vision goggles (NVG), and counterweight (CW) combined with deviated neck postures. Therefore, the purpose of this investigation was to quantify changes in neck loads associated with posture, helmet, NVG, and CW.METHODS: Eight male subjects volunteered. They undertook one of five deviated neck postures (flexion, extension, lateral bending, axial rotation) times four configurations (no helmet, helmet only, helmet and NVG, and helmet, NVG, and CW). 3D kinematics and EMG from 10 muscles (5 bilaterally) drove a 3D inverse dynamics, EMG-driven model of the cervical spine which calculated joint compression and shear at C5-C6.RESULTS: The compression in the neutral posture was 116.5 (5.7) N, which increased to 143.7 (11.4) N due to a 12.7 N helmet. NVGs, weighing 7.9 N, also generated this disproportionate increase, where the compression was 164.2 (3.7) N. In flexion or extension, the compression increased with increasing head-supported mass, with a maximum of 315.8 (67.5) N with the CW in flexion. Anteroposterior shear was highest in the lateral bending [34.0 (6.2) N] condition, but was generally low (< 30 N). Mediolateral shear was less than 5 N for all conditions.DISCUSSION: Repositioning the center of gravity of the helmet with either NVGs or CW resulted in posture-specific changes to loading. Posture demonstrated a greater potential to reposition the head segment's center of gravity compared to the helmet design. Therefore, helmet designs which consider repositioning the center of gravity may reduce loads in one posture, but likely exacerbate loading in other postures.Barrett JM, McKinnon CD, Dickerson CR, Laing AC, Callaghan JP. Posture and helmet configuration effects on joint reaction loads in the middle cervical spine. Aerosp Med Hum Perform. 2022; 93(5):458-466.

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Publisher Full Text (DOI)

Authors

Barrett JM
No affiliation info available
McKinnon CD
No affiliation info available
Dickerson CR
No affiliation info available
Laing AC
No affiliation info available
Callaghan JP
No affiliation info available

MeSH

Biomechanical PhenomenaCanadaCervical VertebraeElectromyographyHead Protective DevicesHumansMaleNeck MusclesPosture

Pub Type(s)

Journal Article

Language

eng

PubMed ID

35551729

Citation

Barrett, Jeff M., et al. "Posture and Helmet Configuration Effects On Joint Reaction Loads in the Middle Cervical Spine." Aerospace Medicine and Human Performance, vol. 93, no. 5, 2022, pp. 458-466.
Barrett JM, McKinnon CD, Dickerson CR, et al. Posture and Helmet Configuration Effects on Joint Reaction Loads in the Middle Cervical Spine. Aerosp Med Hum Perform. 2022;93(5):458-466.
Barrett, J. M., McKinnon, C. D., Dickerson, C. R., Laing, A. C., & Callaghan, J. P. (2022). Posture and Helmet Configuration Effects on Joint Reaction Loads in the Middle Cervical Spine. Aerospace Medicine and Human Performance, 93(5), 458-466. https://doi.org/10.3357/AMHP.5830.2022
Barrett JM, et al. Posture and Helmet Configuration Effects On Joint Reaction Loads in the Middle Cervical Spine. Aerosp Med Hum Perform. 2022 May 1;93(5):458-466. PubMed PMID: 35551729.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Posture and Helmet Configuration Effects on Joint Reaction Loads in the Middle Cervical Spine. AU - Barrett,Jeff M, AU - McKinnon,Colin D, AU - Dickerson,Clark R, AU - Laing,Andrew C, AU - Callaghan,Jack P, PY - 2022/5/13/entrez PY - 2022/5/14/pubmed PY - 2022/5/18/medline SP - 458 EP - 466 JF - Aerospace medicine and human performance JO - Aerosp Med Hum Perform VL - 93 IS - 5 N2 - INTRODUCTION: Between 43 and 97% of helicopter pilots in the Canadian Armed Forces report neck pain. Potential contributing factors include the weight of their helmet, night vision goggles (NVG), and counterweight (CW) combined with deviated neck postures. Therefore, the purpose of this investigation was to quantify changes in neck loads associated with posture, helmet, NVG, and CW.METHODS: Eight male subjects volunteered. They undertook one of five deviated neck postures (flexion, extension, lateral bending, axial rotation) times four configurations (no helmet, helmet only, helmet and NVG, and helmet, NVG, and CW). 3D kinematics and EMG from 10 muscles (5 bilaterally) drove a 3D inverse dynamics, EMG-driven model of the cervical spine which calculated joint compression and shear at C5-C6.RESULTS: The compression in the neutral posture was 116.5 (5.7) N, which increased to 143.7 (11.4) N due to a 12.7 N helmet. NVGs, weighing 7.9 N, also generated this disproportionate increase, where the compression was 164.2 (3.7) N. In flexion or extension, the compression increased with increasing head-supported mass, with a maximum of 315.8 (67.5) N with the CW in flexion. Anteroposterior shear was highest in the lateral bending [34.0 (6.2) N] condition, but was generally low (< 30 N). Mediolateral shear was less than 5 N for all conditions.DISCUSSION: Repositioning the center of gravity of the helmet with either NVGs or CW resulted in posture-specific changes to loading. Posture demonstrated a greater potential to reposition the head segment's center of gravity compared to the helmet design. Therefore, helmet designs which consider repositioning the center of gravity may reduce loads in one posture, but likely exacerbate loading in other postures.Barrett JM, McKinnon CD, Dickerson CR, Laing AC, Callaghan JP. Posture and helmet configuration effects on joint reaction loads in the middle cervical spine. Aerosp Med Hum Perform. 2022; 93(5):458-466. SN - 2375-6322 UR - https://www.unboundmedicine.com/medline/citation/35551729/Posture_and_Helmet_Configuration_Effects_on_Joint_Reaction_Loads_in_the_Middle_Cervical_Spine_ DB - PRIME DP - Unbound Medicine ER -