Apoptosis of endplate chondrocytes in post-laminectomy cervical kyphotic deformity
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ORIGINAL ARTICLE
Apoptosis of endplate chondrocytes in post-laminectomy cervical kyphotic deformity An in vivo animal model in sheep Dechao Kong • Tiansheng Zheng • Jiahu Fang Xiang Li
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Received: 1 December 2012 / Revised: 21 April 2013 / Accepted: 28 April 2013 / Published online: 5 May 2013 Ó Springer-Verlag Berlin Heidelberg 2013
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 followup (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 D. Kong and T. Zheng contributed equally to this work. D. Kong T. Zheng J. Fang (&) X. Li (&) Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing 210029, China e-mail: [email protected] X. Li e-mail: [email protected]
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higher than in the control group, indicating that chondrocyte apoptosis may play a pivotal role in the progress of post-laminectomy cervical kyphosis. Keywords Laminectomy Cervical spine Apoptosis Chondrocyte Sheep
Introduction Cervical spine laminectomy has been widely used to treat spinal tumours, congenital abnormalities, and syrinxes in children [1–7]. However, laminectomy may result in spinal kyphosis and ultimately a deterioration of neural function [8]. Therefore, it is important to understand the pathogenesis of post-laminectomy cervical kyphosis. Previous studies have demonstrated that laminectomy may cause spinal kyphosis as a result of posterior tension band loss. After cervical laminectomy, the integrity of the posterior musculoligamentous structures and posterior bony elements was destroyed, resulting tensile stresses that were preoperatively distributed throughout the posterior ligaments transferred to the facets, causing increased stress on the spinal bodies and leading to deformity [9–11]. Furthermore, age, preoperative loss o
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