To determine the association between the histological findings of ligamentum flavum (LF) and the clinical symptoms or radiological findings of patients with degenerative lumbar disease.

Twenty-six patients with mono-segmental degenerative lumbar diseases (15 patients with spinal stenosis and 11 patients with degenerative spondylolisthesis) underwent a surgical decompression with en bloc resection of the LF. Tissue specimens of the LF were prepared, and the changes in the elastic and collagen fibers were evaluated. The focal lesions were observed in the LF. The following clinical and radiological parameters were investigated in order to determine the possible association with the histological findings: age, gender, preoperative Japanese Orthopaedic Association (JOA) score, the type of neurogenic intermittent claudication, % slip, height of the intervertebral disc, intervertebral angle, intervertebral angle of motion.

There were no significant relationships between the changes in the elastic or collagen fibers and the JOA score. In regard to the focal lesions in the LF, vascularization was observed in 15 cases, calcification in 10, chondrocyte in 9, ossification in 8, ganglion-like cystic lesions in 5 and granulation in 4. The average age of the patients with and without calcification were 70.3 and 63.8 years, respectively. The average preoperative JOA scores of the patients with and without calcification were 13.5 and 15.6 points, respectively. Ossification was more commonly observed in those with degenerative spondylolisthesis (7 cases) than in those with spinal stenosis (1 case).

Various focal lesions in the LF were observed. Calcification was observed more frequently in elderly patients, and the average preoperative JOA scores of the patients with calcification were lower. Ossification was observed more frequently in patients with degenerative spondylolisthesis (7 cases) than in those with spinal stenosis (1 case), suggesting involvement of a mechanical load in the ossification of ligaments.