Correlation between bone mineral density and cervical intervertebral disc degeneration

To study the correlation between cervical intervertebral disc degeneration and bone mineral density, 14 months old, female SD rats were randomly separated into four groups: model group of the ovariectornized rats, model group of cervical disc degeneration, model group of cervical disc degeneration of the ovariectornized rats, and normal control group (sham-surgery). The model of cervical intervertebral disc degeneration of the rats was established by means of resection of the posterior paravertebral muscles from cervical vertebrae. All the rats were killed 4 months after operation in order to observe the changes of bone mineral density (BMD) and assess the morphologic state of the discs. The correlation between BMD data and grades of cervical intervertebral disc degeneration was analyzed in all groups. The results show there is a marked positive correlation between the grades of cervical disc degeneration and the cervical BMD in the model group of cervical disc degeneration and the model group of cervical disc degeneration of the ovariectornized rats (P < 0.01, P < 0.05). A negative correlation between the grades of cervical disc degeneration and the lumbar BMD in the model group of cervical disc degeneration of the ovariectomized rats (P < 0.01). There was the same tendency in the other groups (though no statistical significance). No correlation exists between the cervical disc degeneration and the total-body BMD in all groups. The cervical intervertebral disc degeneration has an positive correlation to cervical BMD, an inverse correlation to lumbar BMD, no correlation to the total-body BMD.