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Cervical Spine Muscle-Tendon Unit Length Differences Between Neutral and Forward Head Postures: Biomechanical Study Using Human Cadaveric Specimens.
Phys Ther. 2017 Jul 01; 97(7):756-766.PT

Abstract

BACKGROUND

Forward head posture (FHP) may be associated with neck pain and poor health-related quality of life. Literature describes only qualitative muscle length changes associated with FHP.

OBJECTIVE

The purpose of this study was to quantify how muscle-tendon unit lengths are altered when human cadaveric specimens are placed in alignments representing different severities of FHP.

DESIGN

This biomechanical study used 13 fresh-frozen cadaveric cervical spine specimens (Occiput-T1, 54±15 y).

METHODS

Specimens' postural changes simulating increasing FHP severity while maintaining horizontal gaze were assessed. Specimen-specific anatomic models derived from computed tomography-based anatomic data were combined with postural data and specimen-specific anatomy of muscle attachment points to estimate the muscle length changes associated with FHP.

RESULTS

Forward head posture was associated with flexion of the mid-lower cervical spine and extension of the upper cervical (sub-occipital) spine. Muscles that insert on the cervical spine and function as flexors (termed "cervical flexors") as well as muscles that insert on the cranium and function as extensors ("occipital extensors") shortened in FHP when compared to neutral posture. In contrast, muscles that insert on the cervical spine and function as extensors ("cervical extensors") as well as muscles that insert on the cranium and function as flexors ("occipital flexors") lengthened. The greatest shortening was seen in the major and minor rectus capitis posterior muscles. These muscles cross the Occiput-C2 segments, which exhibited extension to maintain horizontal gaze. The greatest lengthening was seen in posterior muscles crossing the C4-C6 segments, which exhibited the most flexion.

LIMITATIONS

This cadaver study did not incorporate the biomechanical influence of active musculature.

CONCLUSIONS

This study offers a novel way to quantify postural alignment and muscle length changes associated with FHP. Model predictions are consistent with qualitative descriptions in the literature.

Links

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Authors+Show Affiliations

Khayatzadeh S
Musculoskeletal Biomechanics Laboratory, Edward Hines Jr VA Hospital, Hines, Illinois.
Kalmanson OA
Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois.
Schuit D
Department of Physical Therapy, Governors State University, University Park, Illinois.
Havey RM
Musculoskeletal Biomechanics Laboratory, Edward Hines Jr VA Hospital, Hines, Illinois, and Department of Orthopaedic Surgery and Rehabilitation, Loyola University Chicago.
Voronov LI
Musculoskeletal Biomechanics Laboratory, Edward Hines Jr VA Hospital, and Department of Orthopaedic Surgery and Rehabilitation, Loyola University Chicago.
Ghanayem AJ
Musculoskeletal Biomechanics Laboratory, Edward Hines Jr VA Hospital, and Department of Orthopaedic Surgery and Rehabilitation, Loyola University Chicago.
Patwardhan AG
Musculoskeletal Biomechanics Laboratory, Edward Hines Jr VA Hospital, and Department of Orthopaedic Surgery and Rehabilitation, Loyola University Chicago, 2160 S First Ave, Maywood, IL 60153 (USA).

MeSH

AdultAgedBiomechanical PhenomenaCadaverCervical VertebraeComputer SimulationFemaleHead MovementsHumansImaging, Three-DimensionalMaleMiddle AgedModels, BiologicalNeck MusclesNeck PainParaspinal MusclesPostureSuperficial Back MusclesYoung Adult

Pub Type(s)

Journal Article

Language

eng

PubMed ID

28444241

Clinical Trial Links

Factors Affecting Neck Posture in Academicians With Non-specific Neck Pain

Citation

Khayatzadeh, Saeed, et al. "Cervical Spine Muscle-Tendon Unit Length Differences Between Neutral and Forward Head Postures: Biomechanical Study Using Human Cadaveric Specimens." Physical Therapy, vol. 97, no. 7, 2017, pp. 756-766.
Khayatzadeh S, Kalmanson OA, Schuit D, et al. Cervical Spine Muscle-Tendon Unit Length Differences Between Neutral and Forward Head Postures: Biomechanical Study Using Human Cadaveric Specimens. Phys Ther. 2017;97(7):756-766.
Khayatzadeh, S., Kalmanson, O. A., Schuit, D., Havey, R. M., Voronov, L. I., Ghanayem, A. J., & Patwardhan, A. G. (2017). Cervical Spine Muscle-Tendon Unit Length Differences Between Neutral and Forward Head Postures: Biomechanical Study Using Human Cadaveric Specimens. Physical Therapy, 97(7), 756-766. https://doi.org/10.1093/ptj/pzx040
Khayatzadeh S, et al. Cervical Spine Muscle-Tendon Unit Length Differences Between Neutral and Forward Head Postures: Biomechanical Study Using Human Cadaveric Specimens. Phys Ther. 2017 Jul 1;97(7):756-766. PubMed PMID: 28444241.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Cervical Spine Muscle-Tendon Unit Length Differences Between Neutral and Forward Head Postures: Biomechanical Study Using Human Cadaveric Specimens. AU - Khayatzadeh,Saeed, AU - Kalmanson,Olivia A, AU - Schuit,Dale, AU - Havey,Robert M, AU - Voronov,Leonard I, AU - Ghanayem,Alexander J, AU - Patwardhan,Avinash G, PY - 2015/09/09/received PY - 2017/04/07/accepted PY - 2017/4/27/pubmed PY - 2017/9/12/medline PY - 2017/4/27/entrez SP - 756 EP - 766 JF - Physical therapy JO - Phys Ther VL - 97 IS - 7 N2 - BACKGROUND: Forward head posture (FHP) may be associated with neck pain and poor health-related quality of life. Literature describes only qualitative muscle length changes associated with FHP. OBJECTIVE: The purpose of this study was to quantify how muscle-tendon unit lengths are altered when human cadaveric specimens are placed in alignments representing different severities of FHP. DESIGN: This biomechanical study used 13 fresh-frozen cadaveric cervical spine specimens (Occiput-T1, 54±15 y). METHODS: Specimens' postural changes simulating increasing FHP severity while maintaining horizontal gaze were assessed. Specimen-specific anatomic models derived from computed tomography-based anatomic data were combined with postural data and specimen-specific anatomy of muscle attachment points to estimate the muscle length changes associated with FHP. RESULTS: Forward head posture was associated with flexion of the mid-lower cervical spine and extension of the upper cervical (sub-occipital) spine. Muscles that insert on the cervical spine and function as flexors (termed "cervical flexors") as well as muscles that insert on the cranium and function as extensors ("occipital extensors") shortened in FHP when compared to neutral posture. In contrast, muscles that insert on the cervical spine and function as extensors ("cervical extensors") as well as muscles that insert on the cranium and function as flexors ("occipital flexors") lengthened. The greatest shortening was seen in the major and minor rectus capitis posterior muscles. These muscles cross the Occiput-C2 segments, which exhibited extension to maintain horizontal gaze. The greatest lengthening was seen in posterior muscles crossing the C4-C6 segments, which exhibited the most flexion. LIMITATIONS: This cadaver study did not incorporate the biomechanical influence of active musculature. CONCLUSIONS: This study offers a novel way to quantify postural alignment and muscle length changes associated with FHP. Model predictions are consistent with qualitative descriptions in the literature. SN - 1538-6724 UR - https://www.unboundmedicine.com/medline/citation/28444241/Cervical_Spine_Muscle_Tendon_Unit_Length_Differences_Between_Neutral_and_Forward_Head_Postures:_Biomechanical_Study_Using_Human_Cadaveric_Specimens_ L2 - https://academic.oup.com/ptj/article-lookup/doi/10.1093/ptj/pzx040 DB - PRIME DP - Unbound Medicine ER -