辐照冻干骨板引导羊椎板再生的实验研究

Induced Regeneration of Vertebra Lamina in Sheep Using Freeze-dried,Radiated Sterilized Allogeneic Bone Sheet

目的本实验旨在观察辐照同种骨组织工程材料在羊椎板切除术后引导椎板再生方面的现象,并探讨其作用和机制。方法取12只成年雄性绵羊行L3/4和L4/5全椎板切除建立椎板缺损模型,在其中一处用“H”型同种冻干辐照骨板覆盖,另一处作自身空白对照。于术后4周,8周,12周,16周,20周,24周取材,行大体,X线摄片和骨组织学观察;并对4周,24周取材行CT扫描。结果术后4周,在实验节段可见同种骨板形态、位置保持完好,椎管内无狭窄,硬膜囊无压迫;镜下椎板咬除缘有多量新生骨小梁生成,周边有大量软骨细胞及其分泌粘多糖和坏死后所留下空腔,骨板内侧有增生纤维组织及少量炎症细胞浸润。术后24周,实验节段椎板再生已基本完成,覆盖骨板吸收贻尽,并与再生椎板融合,椎管形态完好,硬膜外未见瘢痕组织。对照节段术后4周可见大范围致密的纤维组织夹杂变性坏死肌肉组织嵌入椎板缺损处,硬膜广泛粘连,硬膜囊受压,24周时对照节段椎板再生未完成,瘢痕组织自椎管外嵌入椎管内,压迫硬膜囊及脊髓,硬膜外间隙几乎消失。再生节段与对照节段相比硬膜粘连程度明显减轻(P<0.01),椎管内容积无明显改变,硬膜囊形状保持良好,无明显压迫。结论同种辐照骨板具有良好的生物相容性、生物力学性能和诱导成骨作用,是一种良好的硬膜外覆盖材料;能有效阻止硬膜外粘连,防止术后再狭窄,并成功引导椎板再生,可用于临床椎板切除术后节段性椎板覆盖成形术。

Objectiv Evaluate the curative effect of bone sheet in inducing vertebra lamina regeneration and preventing the complication of laminectomy. Methods The animal models of L3/4 and L4/5 laminectomy were performed in twelve adult male sheep. After laminectomy of L3/4 and L4/5, L3/4 was covered by freeze-dried, radiated sterilized allogeneic bone sheet in ＂H＂ shape while L4/5 was left as control without treated in six sheep. In the other six sheep, L4/5 was covered by ＂H＂ shaped bone sheet while L3/4 was uncovered as control without treated. Vertebra lamina regeneration process and the dura adhesion degree were observed on the 4^th, 8^th , 12^th, 16^th, 20^th and 24^th weeks after operation. X-ray and CT scan was performed in both segments of L3/4 and L4/5 on 4^th and 24^th weeks. Results On the 4^th week post-operation in experimental segments, the position of the allogeneic bone sheets didn＇t shift; no lumber spinal stenosis or compression of the dura was abserved. On the 24^th week postoperation in experimental segments, vertebral lamina regenerated completed, the allograft has almost been absorbed and fused with vertebral lamina. On the 4^th week post-operation in control segments, scar and necrotic muscles inset into the canalis vertebralis and compressed the dura. On the 24^th week post-operation in control segments, vertebral lamina regeneration were not completed, the scar still compressed the dura and the spinal cord, the epidural area were almost disappear. Compared with the bone sheet covered segments, the dura adhesion degree in the control segments are severer significantly（ P 〈 0.01 ）. Conclusion Due to its good biocompatibility, biomechanieal characters and osteogenic ability, freeze-dried, radiated sterilized allogeneic bone sheet can effectively reduce the pest-laminectomy scar formation and prevent recurrence of post-laminectomy spinal stenosis, induced vertebral lamina regeneration. It is an ideal material for extradural laminoplasty.