A Biomechanical Analysis of Cervical Spine Posture using Geometric Morphometrics

Abstract

Tablet ownership in the United States has increased rapidly in the past decade. With this increase in tablet use comes increased levels of neck flexion compared to using a desktop or laptop computer use. These neck postures have been linked to increases in neck pain. Importantly, tablet viewing postures can be achieved in multiple ways and could be determined by either the morphology of the individual or other extraneous factors. In this study, we aim to preliminarily evaluate how neck postures vary among individuals with the goal of further examining how neck morphology and postures may be related to other factors such sex and height of the subject. We utilize geometric morphometric methods to evaluate the biomechanics of the cervical spine and skull in various neck postures; this technique is excellent for evaluating shape variation and has not been extensively applied in the biomechanical literature. Lateral‐view radiographs of 22 college‐aged subjects (10 female, 12 male) were taken seated in 5 neck postures: neutral, maximum neck flexion, upright seated tablet viewing, semi‐reclined tablet viewing, and reclined tablet viewing. In addition to the radiographs, a participant survey was completed to indicate the presence or absence of discomfort and/or abnormalities of the neck and mandible (e.g., pain, clicking/popping at the TMD, stiffness). Eighty‐seven two‐dimensional landmarks were placed on the cervical spine and skull on each radiograph signifying osteological features of the face, positions of the posterior‐most occlusal molars, the mandible, and the morphology of the cervical vertebrae. Variation among positions and subjects was visualized using principal components analysis and thin‐plate spline analysis. A series of ANOVAs and regression models were performed to examine relationships between morphology and other factors such as sex, weight, height, and the presence of symptoms related to temporomandibular joint disorder (TMD). Separate one‐way ANOVAs for each neck posture indicate that every posture but neutral is achieved differently by sex, with males tending to flex more at the atlanto‐occipital joint than females, and females showing greater protrusion in the neck than males. We further observed a significant relationship between neck flexion and height, suggesting that neck length may influence how subjects adopt specific postures. Though we did not observe a significant relationship between neck morphology or postures and the presence of TMD, these findings may provide some insight into why females experience higher rates of TMD, given that increased neck protrusion has been linked increased stresses on the temporomandibular joint and jaw. This study establishes a framework for future research that focuses on evaluating how neck postures vary in relation to TMD.Support or Funding Information Arkansas Student Undergraduate Research Fellowship University of Arkansas Provost's Collaborative Research Grant This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.