Dropped head syndrome, which has been increasingly reported in recent years, requires correction of cervical kyphosis and may require long-range fixation extending from the cervical to the thoracic spine. Assessing vertebral bone structure may be important for preventing instrumentation failure in the upper thoracic spine, which is a potential complication of surgery. In this study, we evaluated volumetric bone mineral density, trabecular bone porosity, and cortical calcification in the cervical and upper thoracic spine using three-dimensional (3D) trabecular structure measurement software. The study included 79 patients with cervical spine disorders who underwent various surgical procedures and preoperative imaging, including dual-energy X-ray absorptiometry and computed tomography (CT) scans from C3 to Th3. Quantitative analysis using specialized software assessed volumetric bone mineral density and trabecular and cortical bone parameters, and statistical analyses were performed to examine correlations between imaging metrics and indicators of bone fragility. Two-dimensional CT evaluation revealed different trends between cancellous and cortical bone in the cervical and thoracic spine, suggesting that detailed 3D evaluation may also be important.