Posterior longitudinal ligament ossification is a pathological phenomenon whose etiology is still unclear, and ossification of the posterior longitudinal ligament of the thoracic spine (TOPLL) is not clinically common, with a reported incidence of 0.8% [1], however, TOPLL is often progressively aggravated once detected, leading to severe spinal cord injury and even paralysis, which seriously affects the quality of life of patients, and because of the small mobility of the thoracic spine, dynamic factors are not key in spinal cord lesions. Once the symptoms of nerve compression appear, conservative treatment such as resting is often ineffective, and surgery becomes the only solution [2]. In addition, due to the anatomical characteristics of the blood supply, the thoracic spinal cord cannot be extended to this area by the large medullary artery, which is an ischemic area. Therefore, the surgical treatment of ossification of the posterior longitudinal ligament of the thoracic spine is a challenging and difficult operation in spine surgery. 18 cases of ossification of the posterior longitudinal ligament of the thoracic spine were treated with posterior 360° annular decompression pedicle screw internal fixation from December 2009 to November 2013 in our department, which are reported below. 1.1 Data and methods 1.1 General data In this group of cases, there were 8 males and 10 females; age ranged from 32 to 67 years old, with an average of 51 years old, and preoperative X-ray, CT and MRI were routinely performed. 4 cases of ossification of the combined ligamentum flavum, 5 cases of the upper thoracic segment, 13 cases of the middle and lower thoracic segment; 5 cases of the limited type, 4 cases of the segmental type, 6 cases of the continuous type, and 3 cases of the mixed type. 1.2 Treatment 1.2.1 After satisfactory general anesthesia, the patient was placed in prone position with abdomen suspended and C-arm positioning, and the decompression range was determined with the lesioned segment as the center, and a posterior median incision was made with the upper and lower range being 1-2 vertebral segments beyond the decompressed segment, and the skin, subcutaneous and fascial layers were incised in turn, and the paravertebral muscles were peeled off to reveal the spinous process, the vertebral plate and the articular eminence, and the pedicle screws for fixation were implanted in the upper and lower segments of the decompressed segment. The pedicle screws for fixation are implanted in the upper and lower segments of the segment to be decompressed, and the laminae are incised in the medial axis of the small joints on both sides with the application of a grinding drill to complete the “uncovering”, and the connecting rods are installed on one side for pre-fixation, and the operation is performed on the opposite side. After revealing the dura and the posterior longitudinal ligament in front of it, the posterior aspect of the diseased vertebral body was removed with a grinding drill, leaving only a thin layer of bone cortex in front of the dura. The ossified posterior longitudinal ligament is excised or collapsed into the vertebral body. The connecting rod of the pedicle screw is reattached and reattached, and a posterior posterolateral bone graft is performed using the resected posterior accessory bone block of the vertebral body. The dura mater is covered with gelatin sponge, a drainage tube is placed, and the wound is closed layer by layer to end the procedure. 1.2.2 Intraoperative and postoperative treatment Intraoperative routine evoked potential detection and 40mg methylprednisolone intravenous drip; postoperative routine application of hormones for 4-6 days to eliminate spinal cord reactive edema and inflammation; application of neurotrophic drugs to promote neurological recovery; drainage tube routinely removed 2 days after surgery, if there is cerebrospinal fluid leakage, it can be removed a little later 1-2 days; 2 weeks after surgery wearing a brace to get out of bed. 1.3 Observation items and methods General information such as: bleeding volume, operation time, complications, etc. were recorded. The Japanese Orthopaedic Association score [3] was used to assess the recovery of neurological function in the immediate postoperative period and at the last follow-up; to assess the rate of improvement. The surgical efficacy was evaluated using and criteria, excellent: symptoms disappeared and normal life and work ability were restored; good: symptoms were significantly reduced and normal life and light work could be maintained; improved: symptoms were reduced and life could not be taken care of; poor: symptoms did not improve or worsened. 1.4 Statistical treatment SPSSll.0 statistical software was used for analysis and comparison, and the difference was statistically significant by test comparing the preoperative and postoperative scores, P.05.