title: Prevalence, Distribution, and Significance of Incidental Thoracic Ossification of the Ligamentum Flavum in Korean Patients with Back or Leg Pain : MR-Based Cross Sectional Study.
abstract: OBJECTIVE
  Thoracic ossification of the ligamentum flavum (OLF) is a relatively rare disease. Because of ambiguous clinical symptom, it is difficult for early diagnosis of OLF and subsequent treatment can be delayed or missed. Therefore, the purpose of this study is to comprehensively assess the prevalence and distribution of thoracic OLF by magnetic resonance imaging (MRI) and coexisting spinal disease in Korean patients with back pain or leg pain.
  
  
  METHODS
  The sample included 2134 Korean patients who underwent MRI evaluation for back pain. The prevalence and distribution of thoracic OLF were assessed using lumbar MRI with whole spine sagittal images. Additionally, we examined the presence of coexisting lumbar and cervical diseases. The presence of thoracic OLF as well as clinical parameters such as age, sex, and surgery were retrospectively reviewed.
  
  
  RESULTS
  The prevalence of thoracic OLF in total patients was 16.9% (360/2134). The prevalence tended to increase with aging and was higher in women than in men. The lower thoracic segment of T10-11 was the most frequently affected segment. Of the 360 patients with OLF, 31.9% had coexisting herniated thoracic discs at the same level. Approximately 74% of the patients with OLF had coexisting lumbar and cervical disease. Nine (2.5%) of 360 OLF patients underwent surgery for thoracic lesion.
  
  
  CONCLUSIONS
  The prevalenceof thoracic OLF was relatively higher than those of previous reports. And coexisting lumbar and cervical disease were very frequent. Therefore, we should check coexisting spinal diseases and the exact diagnostic localization of ossification besides lumbar disease.
authors.affiliation: Department of Neurosurgery, Chonnam National University Hospital and Medical School, Gwangju, Korea.
authors.forename: Bong Ju
authors.initials: BJ
authors.lastname: Moon
authors.affiliation: Department of Neurosurgery, Gangnam Severance Hospital, The Spinal and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sung Uk
authors.initials: SU
authors.lastname: Kuh
authors.affiliation: Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sungjun
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Gangnam Severance Hospital, The Spinal and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Keun Su
authors.initials: KS
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Gangnam Severance Hospital, The Spinal and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Yong Eun
authors.initials: YE
authors.lastname: Cho
authors.affiliation: Department of Neurosurgery, Gangnam Severance Hospital, The Spinal and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Dong Kyu
authors.initials: DK
authors.lastname: Chin
keywords: Ligamentum flavum; Lumbar disease; Ossification; Prevalence; Thoracic spine; Yellow ligament