UMTRI Project

Evaluation of Cervical Spine Geometry in the Automotive Seated Posture

Sponsor: Ford Motor Company
Investigator: Kathleen DeSantis Klinich
04/01/2000 - 12/31/2003

In the mid 1970s, UMTRI investigated the biomechanical properties of the head and neck using 180 “normal” adult subjects selected to fill eighteen subject groups based on age (young, middle age, elderly), gender, and stature (short, medium, and tall by gender). Lateral radiographs of the subjects’ heads and necks were taken with the subjects seated in an automotive neutral posture, as well as with their head/neck in full- voluntary flexion and full-voluntary extension. Although the cervical spine and lower head geometry were previously measured manually and documented, new technologies have enabled computer digitization of the scanned x-ray images and a more comprehensive and detailed analysis of the variation in cervical-spine and lower head geometry with subject age, stature, and gender. After scanning the radiographic images, 108 skeletal landmarks on the cervical vertebrae and 10 head landmarks were digitized using NIH Image for the neutral head/neck posture and for a subset of these landmarks in the full-flexion and full-extension postures. These data were used to characterize neutral-posture cervical-spine curvatures using Bézier spline functions and a curvature index. Commonly used vertebral dimensions and shape parameters were also calculated for each subject. Cervical-spine curvature, vertebral size and shape, and overall neutral posture orientation trends were analyzed as functions of age, stature, and gender. Results from the study have been incorporated into a software package that allows users to generate cervical-spine geometries for occupants of specified age, gender, and stature. In the mid 1970s, UMTRI investigated the biomechanical properties of the head and neck using 180 “normal” adult subjects selected to fill eighteen subject groups based on age (young, middle age, elderly), gender, and stature (short, medium, and tall by gender). Lateral radiographs of the subjects’ heads and necks were taken with the subjects seated in an automotive neutral posture, as well as with their head/neck in full- voluntary flexion and full-voluntary extension. Although the cervical spine and lower head geometry were previously measured manually and documented, new technologies have enabled computer digitization of the scanned x-ray images and a more comprehensive and detailed analysis of the variation in cervical-spine and lower head geometry with subject age, stature, and gender. After scanning the radiographic images, 108 skeletal landmarks on the cervical vertebrae and 10 head landmarks were digitized using NIH Image for the neutral head/neck posture and for a subset of these landmarks in the full-flexion and full-extension postures. These data were used to characterize neutral-posture cervical-spine curvatures using Bézier spline functions and a curvature index. Commonly used vertebral dimensions and shape parameters were also calculated for each subject. Cervical-spine curvature, vertebral size and shape, and overall neutral posture orientation trends were analyzed as functions of age, stature, and gender. Results from the study have been incorporated into a software package that allows users to generate cervical-spine geometries for occupants of specified age, gender, and stature.