Spontaneous reduction of a floated ossification of the ligamentum flavum after posterior thoracic decompression (floating method); report of a case (abridged translation of a primary publication)

Abstract

Background context: Although complete resection is the preferred surgical treatment for ossification of the ligamentum flavum (OLF), it sometimes results in the floating method because of adhesion to, or ossification of, the dura mater. It is difficult to anticipate the degree of floating, and if the floated ossification is large, decompression of the spinal cord may not be sufficient.

Purpose: To describe a case of spontaneous reduction of a floated OLF after posterior decompression.

Study design: Case report and review of the literature.

Methods: A 70-year-old woman with OLF of the thoracic spine presented with gait disturbance. A computed tomographic myelogram showed a large ossification and severe spinal canal stenosis at T10-T11. It also showed slight spinal cord compression by ossification at T9-T10.

Results: We performed a laminectomy with floating ossification at T9-T11 and posterior fusion with a pedicle screw system at T10-T11. After the operation, the patient's neurologic improvement was excellent. Five weeks after the operation, a computed tomogram showed reduction of the floated ossification. Improvement progressed up to 3 months after the operation, bringing a sufficient decompression of the spinal cord, whereas it was insufficient immediately after the operation.

Conclusions: Our present study is the first report that showed OLF was reduced after the floating method. Reduction of the floated ossification was observed 5 weeks after the operation.

Keywords: Floating method; Myelopathy; Ossification of the ligamentum flavum; Thoracic spine.