Ossification of the posterior longitudinal ligament and ligamentum flavum: imaging features.

Ossifications of the posterior longitudinal ligament and ligamentum flavum are both special subcategories of degenerative diseases responsible for compression of the spinal cord. Ossification of the ligaments is well demonstrated by plain radiography and computed tomography. Magnetic resonance imaging noninvasively provides useful information about the degree and extent of spinal cord compression as well as the character of the ossification. T2-weighted sequences are most effective to evaluate both spinal cord compression due to the ossification and abnormal signal intensity of the spinal cord.