Abstract
PURPOSE: The present study was performed to establish an animal model of cervical kyphosis after laminectomy (C2-C5), and to determine the role of endplate chondrocytes apoptosis in cervical kyphosis after laminectomy. METHODS: Twenty-four 3-month-old sheep were randomly divided into two groups: the laminectomy group (n = 12), and the control group (n = 12). The cervical spine alignment was evaluated on a lateral cervical spine X-ray using Harrison's posterior tangent method before surgery and at follow-up. Cartilaginous endplate chondrocyte apoptosis was confirmed using transmission electron microscopy and terminal deoxyribonucleotidyl transferase (TdT)-mediated dUTP nick-end labelling. RESULTS: The mean preoperative cervical curvature (C2-5) in the surgery group was -15.8°. The cervical curvature was 19.1° at 3 months post-operation and decreased to 20.2° at the final follow-up postoperatively. The cervical curvature was significantly decreased in the laminectomy group compared with the control group at the last follow-up (P < 0.001), which was a direct indication of kyphotic change. The incidence of apoptotic cells in the surgery group was significantly higher at the 3- and 6-month follow-up than the incidence in the control group. CONCLUSIONS: The frequency of endplate chondrocyte apoptosis in the laminectomy group was significantly higher than in the control group, indicating that chondrocyte apoptosis may play a pivotal role in the progress of post-laminectomy cervical kyphosis.