Ligamentum flavum in lumbar spinal stenosis, disc herniation and degenerative spondylolisthesis. An histopathological description.

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. RESULTADOS: Los cambios histopatologicos mas frecuentes fueron la hialinizacion y la fragmentacion de las fibras de colageno (34%), neovascularizacion en 40.3%, y la disposicion irregular de las fibras elasticas es el cambio mas frecuente con 56.7% del total de muestras. Existe una diferencia en la presencia de cambios en el LF, de acuerdo con el diagnostico, siendo estadisticamente significativo para la fragmentacion de las fibras de colageno (p = 0.045), la degeneracion quistica (p = 0.001), la apariencia fibrilar (p = 0.007) y la hipercelularidad (p = 0.005) todos ellos, siendo mas frecuentes en el grupo LDS. El grupo LHD presento fragmentacion de las fibras de colageno en 45.5% (p = 0.045) y la apariencia fibrilar en 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.