Abstract： BACKGROUND: The appearances of spiral computer tomograph (CT) and three-dimensional image processing are of very importance for fully evaluating preoperative pathological changes,which represent various cervical spondylotic myelopathy (CSM) in clinic, and choosing proper clinical therapeutic occasion and methods.OBJECTIVE: To analyze the effects of imageological image and technical advantages of three-dimensional spiral CT on the preoperative evaluation and surgical plan of CSM.DESIGN: Retrospective analysis, controlled observation.SETTING: Nanjing First Hospital Affiliated to Nanjing Medical University. PARTICIPANTS: Altogether 268 patients with CSM admitted to Nanjing First Hospital from January 2002 to January 2005 were involved in this experiment. The involved patients were randomly assigned into preoperative evaluation group (n =146) and control group (n =122). The baseline materials of two groups were comparable.METHODS:Preoperative evaluation group: ① CT scan and three-dimensional reconstruction: Helical scanning was conducted at transverse plane with TOSHIBA-HiSpeed/I screw machine. After scanning, reconstruction was performed finally, three-dimensional reconstruction was conducted on computer workstation (RadworkS. 1 ). Correlative data were measured and analyzed with image analysis software (ADW3.1). ② Design of three-dimensional CT-assisted operation plan: Cervical vertebral osseous anatomic landmark and the anatomic relationship of its adjacent structure were revealed stereoscopically. Individual orthopaedic location marker could be provided. Preoperative routine CT examination was performed in the control group with conventional operation method.MAIN OUTCOME MEASURES: ① The hyperostosis of vertebral body, hamular process joint and small articular process were observed. ②The degree and type of intervertebral disc protrusion were observed. ③The changes of hyperostosis before and behind the vertebral canal. Spinal decompression was observed by CT virtual endoscopy (CT-VE).RESULTS: All the 268 patients participated in the result analysis. ① In the preoperative evaluation group, 129 patients were found with intervertebral disc protrusion, 109 patients with vertebral posterior marginal hyperostosis, 61 patients with hypertrophic ligamentum flavum and corrugation, 27 patients with posterior longitudinal ligament calcification, 31 patients with hyperostosis at small articular process, 29 patients with vertebral plate thickening and 18 patients with vertebral olisthy. The visible anatomical structures were in accord with clinical manifestations and imageological structures. Death, laryngeal nerve injury, bone graft displacement, infection and other complications were not found in all the patients. In the postoperative 6th month, X-ray image showed that all the patients had good bone graft fusion, and no titanic plate or bolt loosening or fragmentation was found. The excellent and good rate evaluated by Odom was 95.9%.② In the control group, postoperative X-ray image and CT showed that vertebral canal decompression of 24 patients was not fully, and the positions of titanic plate or bolt of 17 patients were not satisfying. The excellent and good rate evaluated by Odom (84.4%) in the control group was lower than that in the preoperative evaluation group (P＜0.05).CONCLUSION: Preoperative observation of cervical vertebral individual three-dimensional CT is helpful to exactly and generally evaluate cervical spondylotic myelopathy and assistantly make operative plan, whick makes intraoperative manipulation more exactive, safer and easier to be controlled.