Introduction:

Changes in ligamentum flavum (LF) related to degeneration are secondary to either the aging process or mechanical instability. Previous studies have indicated that LF with aging shows elastic fiber loss and increased collagen content, loss of elasticity may cause LF to fold into the spinal canal, which may further narrow of the canal.

Material and methods:

A total of 67 patients operated with the surgical indications of lumbar spinal stenosis (LSS), lumbar disc herniation (LDH) and lumbar degenerative spondylolisthesis (LDS) were included. LF samples were obtained from patients who had LSS (39), LDH (22) and LDS (6). Specimens were examined with regard to chondroid metaplasia, calcification, fragmentation of collagen fibers, cystic degeneration, fibrillar appearence, and hypercellularity.

Results:

The most frequent histopathological changes were hyalinization and fragmentation of collagen fibers occur in 34%, neovascularization in 40.3% and irregular arrangement of elastic fibers is the most prevalent change with 56.7% of the total samples. There is a difference in the presence of certain changes in the LF according to the diagnosis, being statistically significant for fragmentation of collagen fibers (p = 0.045), cystic degeneration (p = 0.001), fibrillar appearance (p = 0.007) and hypercellularity (p = 0.005) all of these, being more prevalent in LDS group. LHD group presented fragmentation of collagen fibers in 45.5% (p = 0.045) and fibrillar appearance in 4.5% (p = 0.009).

Conclusions:

There is not evidence of cellular hyperthophy in the histhopatological analyses, thickening of the LF can be seen by bulking of LF followed by collapse of motion segment.