Myelopathy caused by ossification of ligamentum flavum

Retrospective study of seven cases of ossification of ligamentum flavum from two urban hospitals in a Chinese population.

To inspect the epidemiology, clinical presentation, pathology, and treatment outcome in these Chinese patients with ossification of ligamentum flavum.

Ossification of ligamentum flavum involving the lower thoracic region is relatively common in the Japanese population. It is usually presented with myelopathy of progressive nature.

Five patients were male and two were female. The mean age was 52 years (range 41-73 years). Diagnosis was made by CT scan, MRI, and subsequent histology. Six patients have been treated by laminectomy and one by laminoplasty. The average follow-up duration is 34 months (range 26-44 months). The outcome is evaluated by Japanese Orthopaedics Association (JOA) score.

The average time of presentation from the onset of symptoms was 9 months (range 3-12 months). Most of the patients presented with lower limb numbness and gait disturbance. One case was presented after a minor trauma. Mean JOA score was 4.8 (range 2-7, of 11). The lower thoracic level was the most frequently involved region. One case was associated with ossification of the posterior longitudinal ligament. Two patients had transient postoperative neurologic deterioration, which improved subsequently. Mean percentage of recovery after surgery in terms of JOA score is 65% (25-100%), with a mean final JOA score of 7.8.

Ossification of ligamentum flavum is an uncommon cause of myelopathy in the Chinese population. It can present acutely after minor trauma. Posterior decompression, especially with en bloc dissection of laminae, gives satisfactory results.