title: Microendoscopic posterior decompression for the treatment of thoracic myelopathy caused by ossification of the ligamentum flavum: a technical report.
abstract: Ossification of the ligamentum flavum (OLF) is a common cause of progressive thoracic myelopathy in East Asia. Good surgical results are expected for patients who already show myelopathy. Surgical decompression using a posterior approach is commonly used to treat OLF. This study investigated the use of microendoscopic posterior decompression for the treatment of thoracic OLF.
  
  
  
  Microendoscopic posterior decompression was performed on 9 patients with myelopathy. Patients had a mean age of 59.8 years and single-level involvement, mostly at the T10-11 and T11-12 vertebrae. Computed tomography and magnetic resonance imaging were used to classify the OLF. A tubular retractor and endoscopic system were used for microendoscopic posterior decompression. Midline and unilateral paramedian approaches were performed in 2 and 7 patients, respectively. Intraoperative motor evoked potentials (MEPs) of 7 patients were monitored. Pre- and postoperative neurological status was evaluated using the modified Japanese Orthopaedic Association (mJOA) score.
  
  
  
  Thoracic OLF for all patients were classed as bilateral type with a round morphology. Improvement of MEPs at least one muscle area was recorded in all patients following posterior decompression. A dural tear in one patient was the only observed complication. The mean recovery rate was 44.9 %, as calculated from mJOA scores at a mean follow-up period of 20 months.
  
  
  
  Microendoscopic posterior decompression combined with MEP monitoring can be used to treat patients with thoracic OLF. The optimal surgical indication is OLF at a single vertebral level and of a unilateral or bilateral nature, without comma and tram track signs, and a round morphology.
authors.affiliation: Department of Orthopaedics, Iwai Orthopaedic Medical Hospital, 8-17-2 Minamikoiwa Edogawa-ku, Tokyo, 133-0056, Japan.|Department of Orthopaedic Surgery, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo, 113-8655, Japan.|Department of Orthopaedics, Japan Community Health Care Organization Tokyo Shinjuku Medical Center, 5-1 Tsukudo-cho Shinjuku-ku, Tokyo, 162-8543, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Baba
authors.affiliation: Department of Orthopaedics, Iwai Orthopaedic Medical Hospital, 8-17-2 Minamikoiwa Edogawa-ku, Tokyo, 133-0056, Japan.|Department of Orthopaedic Surgery, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Oshima
authors.affiliation: Department of Orthopaedics, Iwai Orthopaedic Medical Hospital, 8-17-2 Minamikoiwa Edogawa-ku, Tokyo, 133-0056, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Iwahori
authors.affiliation: Department of Orthopaedics, Iwai Orthopaedic Medical Hospital, 8-17-2 Minamikoiwa Edogawa-ku, Tokyo, 133-0056, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Takano
authors.affiliation: Department of Orthopaedics, Iwai Orthopaedic Medical Hospital, 8-17-2 Minamikoiwa Edogawa-ku, Tokyo, 133-0056, Japan.
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Inanami
authors.affiliation: Department of Orthopaedics, Iwai Orthopaedic Medical Hospital, 8-17-2 Minamikoiwa Edogawa-ku, Tokyo, 133-0056, Japan. hkoga0808@gmail.com.|Department of Minimally Invasive Spinal Surgery, Zhangzhou Zhengxing Hospital, No.1608 North Circle Road State Highway, 363000, Zhangzhou, Fujian Province, China. hkoga0808@gmail.com.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Koga
mesh_terms: D000328:Adult; D000368:Aged; D019299:Decompression, Surgical / Q000379:methods*; D004724:Endoscopy / Q000379:methods*; D005260:Female; D006801:Humans; D017843:Ligamentum Flavum / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000601:surgery*; D013118:Spinal Cord Diseases / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000601:surgery*
keywords: Microendoscopic posterior decompression; Minimally invasive; Ossification of the ligamentum flavum; Thoracic myelopathy