Inclusion Criteria: (1) thoracic myelopathy caused by TOPLL with or without TOLF; (2) severe adhesions between dura mater and ossified lesion with or without dura ossification confirmed intraoperatively; (3) extended posterior circumferential decompression was applied; (4) pedicle screw instrumentations were implanted after decompression; (5) follow-up for more than 6 months; (7) complete clinical data.  Exclusion Criteria:  (1) spinal deformities; (2) thoracic spine fractures; (3) syringomyelia, spinal tumor, myelitis, etc.; (4) coexisted with cervical spondylosis and lumbar stenosis; (5) post operation of thoracic spinal stenosis; (6) recurrent myelopathy caused by lesions in other levels than the decompressed segments.