肌间隙入路腰椎间盘退变模型的构建

目的探讨背最长肌与腹外斜肌间隙入路纤维环穿刺法构建兔腰椎间盘退变模型的可行性。方法新西兰大白兔6只,从兔子背最长肌与腹外斜肌间隙入路暴露椎体和椎间盘,L2/3为对照组,不暴露也不穿刺椎间盘;L3/4为假手术组,剪断L4右侧横突后暴露椎间盘,但不进行穿刺;L4/5、L5/6为穿刺组,剪断L5、L6右侧横突后暴露椎间盘并用18G针穿刺构建模型。分别在术前及术后4周对实验动物进行X线和磁共振(MRI)检查,4周后处死实验动物,取材后行组织学及免疫组织化学检查。结果术后4周,X线检查显示模型组L4/5、L5/6椎间盘高度明显降低、骨赘形成、终板硬化,MRI T2加权像亦见椎间盘高度下降,其椎间盘髓核信号明显减弱;大体观察见该组椎间盘髓核组织较少并组织松脆,呈淡黄色改变;组织学观察髓核脊索细胞数量减少,免疫组织化学观察到髓核Ⅱ型胶原表达比对照组和假手术组明显减少。结论本研究为椎间盘退变的研究提供了一种较为理想的、相对可靠的动物模型。

Establishment of a rabbit model of lumbar intervertebral disc degeneration via the paraspinal approach

Objective To establish a rabbit model of intervertebral disc degeneration by puncturing the anulus fibrosus through an approach between the longissimus dorsi muscle and obliquus externus abdominis.Methods The L4/5 and L5/6 intervetebral discs of 6 New Zealand white rabbits were punctured by an 18-gauge pin in the anterolateral annular fibrosus through an approach between the longissimus dorsi muscle and the obliquus externus abdominis with the right transverse processes of L5 and L6 resected;the L2/3 discs were used as the control without exposure or needle stab,and the L3/4 discs were subjected to sham operation with the discs exposed but not punctured after resecting the right transverse process of L4.X-ray and magnetic resonance imaging(MRI) were performed preoperatively and at the 4th week after puncture.At 4 weeks after the operation,histological and immunohistochemical analyses of the discs were carried out.Results X-ray of the punctured discs at 4 weeks after the operation presented a significant decrease of disc height,osteophytosis formation,and end-plate stiffness;an obvious decrease of signal intensity on T2-weighted images was found in the puncture group but not in the control or sham-operated groups.Gross morphological inspection showed atrophy of the nucleus pulposus,which became loose,soft,and fragile with a light yellow color.Histological and immunohistochemical analyses showed a significant decrease of notochordal cells and type II collagen in the nucleus pulposus in the puncture group as compared to the control and sham-operated groups.Conclusion Puncture through the approach between the longissimus dorsi muscle and the obliquus externus abdominis allows the establishment of a reliable animal model for studying intervertebral disc degeneration.