345 - Slumped Seated Posture Causes Compensatory Hyperlordosis of the Lower...

Oral Posters: Cervical

Presented by: R. Havey - View Audio/Video Presentation (Members Only)

Author(s):

R. Havey(1,2), S. Khayatzadeh(2), J.-C. Le Huec(3), F. Jabbour(3), A. Faundez(4), E. Cohen(2), L. Lomasney(1), L. Voronov(1,2), A. Patwardhan(1,2)

(1) Loyola University Chicago, Orthopaedic Surgery and Rehabilitation, Maywood, IL, United States
(2) Edward Hines Jr. VA Hospital, Hines, IL, United States
(3) Bordeaux University Hospital, Bordeaux, France
(4) Hopital La Tour, Meyrin, Switzerland

Abstract

Introduction: Office workers often experience stiffness and pain in the neck and shoulders at the end of a day sitting at a desk. Slumped seated posture is common among office workers with sedentary work load, despite the advice of ergonomic experts. The goal of this study was to assess changes in the alignment of the head-neck complex when subjects maintain horizontal gaze while seated in a slumped posture as opposed to an erect standing or an erect sitting posture.

Methods: Eleven asymptomatic subjects (10M/1F, 39±12years) participated in the study. Subject were positioned inside an EOS X-ray machine and instructed to assume the following postures: (i) standing erect (P1), (ii) sitting erect (P2), and (iii) sitting slumped (P3). Subjects were instructed to maintain horizontal gaze by looking straight ahead into a full-length mirror mounted in front of the subjects while a full-length lateral radiograph was taken for each posture, with the subject's ears and feet visible on the image. For analysis the cervical spine was divided into two zones: suboccipital (C0-C2), and subaxial (C2-C7). The alignment parameters of the cervical spine and cervical-thoracic junction were compared between the three postures using paired t-tests (P1 vs P2 vs P3). The significance level was set to alpha=0.01 to account for multiple comparisons.

Results: The slumped sitting posture (P3) caused a significant increase in the kyphotic tilt of the T1 vertebra as compared to the standing (P1) posture (47.7 vs. 27.8, p< 0.001) and the sitting erect (P2) posture (47.7 vs. 26.6 degrees, p< 0.001). The C2-C7 angular alignment became more lordotic in the slumped posture as compared to the sitting erect posture (21.8 vs. 8.4 degrees, p=0.004) and the standing posture (21.8 vs. 13.0 degrees, p=0.05). The slumped posture did not affect the alignment of the suboccipital region; the posterior gap between the bony contours of the occiput and C2 spinous process remained unchanged between the three postures (13.3 vs. 12.5 vs. 12.6 mm, p=0.04 and p=0.98, respectively).

Conclusions: The transition from a standing posture to a sitting erect posture did not alter the alignment of the head-neck complex because the slope of the T1 superior endplate, the base of the cervical spine, remained unchanged between these two postures. However, the slumped sitting posture caused a substantial increase in the tilt of T1 and consequently the lower (C2-C7) cervical spine had to undergo increased extension in order to maintain horizontal gaze. This is distinct from the previousy documented compensation mechanism seen in a forward head posture, where the lower cervical spine flexes and the suboccipital (C0-C2) region must extend to maintain horizontal gaze. Chronic hyperextension of the lower cervical spine along with the increased C2-C7 SVA during the work day may increase the burden on the extensor muscles of the cervical spine and cervico-thoracic junction and contribute to increased stiffness and neck pain.

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