title: Surgical results and prognostic factors for thoracic myelopathy caused by ossification of ligamentum flavum: posterior surgery by laminectomy.
abstract: BACKGROUND
  Thoracic ossification of ligamentum flavum (TOLF) of the spine is characterized by a heterotopic bone formation in the thoracic ligamentum flavum, which causes slowly progressing spinal cord injury. Surgical decompression is the most common treatment of choice for patients with compressive myelopathy due to TOLF. However, the surgical outcome is not always satisfactory.
  
  
  METHODS
  To identify the predictors of surgical outcome, we retrospectively studied the associations between various clinical and radiological parameters and postoperative recovery in 78 patients who underwent decompressive laminectomy for thoracic myelopathy due to TOLF between October 1998 and June 2011. Surgical outcomes were assessed using modified Japanese Orthopedic Association (mJOA) recovery rate (RR)/outcome scores.
  
  
  RESULTS
  At a minimum of 1 year after surgery for TOLF treatment, the postoperative clinical scores showed statistically significant changes with improvement in the JOA scores. The results indicated that a longer duration of preoperative symptoms, fused-type TOLF, and the degree of compression of the anteroposterior diameter and ossified region (middle thoracic OLF) was related to poor prognosis.
  
  
  CONCLUSIONS
  Early diagnosis and sufficient surgical decompression improved the functional outcomes of TOLF patients. The surgical risk is relatively higher due to the tenuous blood supply of the spinal cord and the limited spinal canal volume of the middle thoracic spine extending from T4 to T9.
authors.affiliation: Department of Orthopedics, Changhai Hospital, Second Military Medical University, No.168, Changhai Rd, Shanghai, 200433, People's Republic of China.
authors.forename: Shunzhi
authors.initials: S
authors.lastname: Yu
authors.forename: Dajiang
authors.initials: D
authors.lastname: Wu
authors.forename: Fengning
authors.initials: F
authors.lastname: Li
authors.forename: Tiesheng
authors.initials: T
authors.lastname: Hou
mesh_terms: D000328:Adult; D000368:Aged; D019299:Decompression, Surgical / Q000379:methods; D005260:Female; D006801:Humans; D007796:Laminectomy / Q000379:methods; D017843:Ligamentum Flavum / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery; D011184:Postoperative Period; D011859:Radiography; D012189:Retrospective Studies; D013118:Spinal Cord Diseases / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D013119:Spinal Cord Injuries / Q000000981:diagnostic imaging / Q000601:surgery; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome