Cervical spine bone density in young healthy adults as a function of sex, vertebral level and anatomic location.

Abstract

Bone mineral density (BMD) measured using quantitative computed tomography (QCT) has been shown to correlate with bone mechanical properties. Knowledge of BMD within specific anatomic regions of the spine is valuable to surgeons who must secure instrumentation to the vertebrae, to medical device developers who design screws and disc replacements, and to researchers who assign mechanical properties to computational models. The objective of this study was to comprehensively characterize BMD in the cervical spine of young healthy adults. QCT was used to determine BMD in the cervical spines of 31 healthy adults (age 20-35). Subject-specific 3D models of each vertebra were created from CT scans, and anatomic regions of interest were identified in each bone (C1: 3 regions; C2: 9 regions, C3-C7: 13 regions). Statistical tests were performed to identify differences in BMD according to vertebral level, anatomic regions within vertebrae, and sex. BMD varied significantly among vertebral levels and among anatomic regions within each vertebra. Females had higher BMD than males (p = .041) primarily due to higher BMD in the posterior regions of each vertebra. These data can serve as a baseline to identify BMD changes in older and symptomatic patients. This data set is also the first report of volumetric bone density within different anatomic regions of the atlas and axis of the cervical spine. The finding of higher BMD in females is in agreement with the previous QCT results but contradicts DEXA results that are known to be dependent upon bone size.