title: Spinal Cord Kinking in Thoracic Myelopathy Caused by Ossification of the Ligamentum Flavum.
abstract: BACKGROUND
  Ossification of the ligamentum flavum (OLF) is being increasingly recognized as a cause of thoracic myelopathy. This study was to describe a rare clinical entity of spinal cord kinking (SK) in thoracic myelopathy secondary to OLF.
  
  
  METHODS
  The data of 95 patients with thoracic myelopathy secondary to OLF were analyzed retrospectively. The incidence and location of SK were determined using preoperative magnetic resonance imaging (MRI). The clinical presentation and radiological characteristics in patients with SK were analyzed. Posterior en bloc laminectomy with OLF was performed, and the surgical results were evaluated.
  
  
  RESULTS
  SK was found in seven patients (7.4%) based on preoperative MRI. The patients included one male and six females with an average age of 55.6 years (range, 48-64 years). Five patients presented with radiculomyelopathy and two presented with typical thoracic myelopathy of spastic paraparesis. In all cases, the kinking was located just above the end of the spinal cord where the conus medullaris (CM) was compressed by the OLF. The degree of SK varied from mild to severe. The tip of the CM was located between the upper third of T11 to the lower third of L1, above the lower edge of L1. With an average follow-up of 30.4 months, the modified Japanese Orthopedic Association score significantly improved from 5.7 ± 1.8 preoperatively to 8.9 ± 1.4 postoperatively (t = 12.05; P < 0.0001) with an improvement rate of 63.1 ± 12.3%.
  
  
  CONCLUSIONS
  SK is a rare radiological phenomenon. It is typically located at the thoracolumbar junction, where the CM is compressed by the OLF. Our findings indicate that these patients may benefit from a posterior decompressive procedure.
authors.affiliation: Department of Spine Surgery, Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Wang
authors.forename: Min
authors.initials: M
authors.lastname: Pan
authors.forename: Chu-Qiang
authors.initials: CQ
authors.lastname: Yin
authors.forename: Xiu-Jun
authors.initials: XJ
authors.lastname: Zheng
authors.forename: Ya-Nan
authors.initials: YN
authors.lastname: Cong
authors.forename: De-Chun
authors.initials: DC
authors.lastname: Wang
authors.forename: Shu-Zhong
authors.initials: SZ
authors.lastname: Li
mesh_terms: D005260:Female; D006801:Humans; D017843:Ligamentum Flavum / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000150:complications; D011859:Radiography; D013117:Spinal Cord Compression / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery*; D013118:Spinal Cord Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery*