Definition:

Ossified ligamentum flavum (OLF) is a condition of heterotopic lamellar bone formation within the yellow ligament. OLF is a widely described pathology in eastern Asia and rare in other parts of the world. The disease process first causes hypertrophy of the ligamentum flavum and subsequent ossification, which narrows the spinal canal and leads to myeloradiculopathy. The lower thoracic spine is most commonly affected. Previous hyperkyphosis and mechanical stress are thought to be predisposing conditions. It is tempting to think that OLF is genetically or pathologically inherited based on abnormalities of calcium or phosphate metabolism, on endocrinologic abnormalities, or on the presence of autoimmune disease. Such relationships, however, have not been documented. Treatment of cervical stenosis related to OLF is based on the standard principle of managing neural spinal abnormalities. Acute episodes of pain and onset of or increase in neurological deficits are treated with rest, external spinal immobilization with a collar or brace, and analgesics, anti-inflammatory, and/or antispasmodic medicines. Surgery is indicated for patients with acute or chronic progression of neurological deficits or persistent neurological deficits.