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Eur Spine J. 2016 Jun;25(6):1912-9. doi: 10.1007/s00586-015-4158-9. Epub 2015 Jul 30.

Microendoscopic posterior decompression for the treatment of thoracic myelopathy caused by ossification of the ligamentum flavum: a technical report.

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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.
Department of Orthopaedics, Iwai Orthopaedic Medical Hospital, 8-17-2 Minamikoiwa Edogawa-ku, Tokyo, 133-0056, Japan.
Department of Minimally Invasive Spinal Surgery, Zhangzhou Zhengxing Hospital, No.1608 North Circle Road State Highway, 363000, Zhangzhou, Fujian Province, China.



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.


Microendoscopic posterior decompression; Minimally invasive; Ossification of the ligamentum flavum; Thoracic myelopathy

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