To investigate whether tissue-specific expression of estrogen receptor affects morphologic difference of degenerative spinal stenosis.

Forty female patients, who were diagnosed as degenerative spinal stenosis and had undergone spinal surgery, were included in this study. During the surgery, ligamentum flavum and facet joint capsule were harvested. Each tissue was divided into two groups according to axial computed tomography findings. For ligamentum flavum, tissues with thickness of more than 4 mm were put into the hypertrophy group and the others less than 4 mm were put into the control group. Facet joints with one or more signs of osteophyte formation, hypertrophy and destructive change were considered as a degenerative group, the others were considered as a control group. Expression of estrogen receptor was evaluated by immunohistochemistry and enzyme immunoassay using anti-estrogen receptor. The expressions of estrogen receptor were analyzed between the groups at each tissue.

Increased expressions of estrogen receptor were observed in the hypertrophy group of ligamentum flavum or in the degenerative group of facet joint capsule. At the ligamentum flavum, the amounts of estrogen receptor were 8.7 ± 1.5 fmol/mL in hypertrophy group and 5.7 ± 3.4 fmol/mL in control group. The difference was statistically significant (p<0.05) . In facet joint capsule, the amounts of estrogen receptor were 8.1 ± 4.5 fmol/mL for the degenerative group versus 4.9 ± 3.3 fmol/mL for the control group, which was significantly different (p<0.05).

We suggest that different expressions of estrogen receptor in ligamtum flavum and facet joint capsule may relate to morphological differences in degenerative lumbar stenosis.