The purpose of this experiment was to investigate the relationship between sex hormones and degenerative spinal disorder.

22 ligamentum flavum were obtained from 22 patients who had undergone spinal surgery. Patients' specimens were divided into three groups. The experimental group contatining 16 postmenopausal female patients, diagnosed as having degenerative spinal stenosis. As a control group, two groups were formed. The first control group was composed of 4 male patients diagnosed as having same disease and the second group was two premenopausal females, who were diagnosed as having disc herniation and fracture. The relative amount of estrogen receptor expression at gene level was measured by reverse transcription-polymerase chain reaction (RT-PCR). The amounts of expressed gene in each group were compared: receptor subtypes (ER-alpha, ER-beta), sex and age (pre, postmenopausal). The calculated amount of ER-alpha and ER-beta gene expression was standardizised with respect to the mRNA of GAPDH.

The mean density of the estrogen receptor, signals were 55.0±12.3, 143.0±32.1 in the experimental group, 39.6±8.0, 89.7±20.1 in the first control group and 34.1±2.0, 102.5±2.7 in the second control group. The mean density of the estrogen receptor alpha, beta, signals were higher in the experimenal group than in the control group. A statistically significant difference was found between the experimental group and the control group (p<0.05).

The expression of ER-alpha, beta, gene in the human ligamentum flavum was confirmed. It was inferred from this study that a high expression of estrogen receptor might affect ligamentum flavum hypertropy in postmenopausal women and that this is likely to be a pre-disposing factor for degenerative spinal disorder.