一种新的兔椎体成形术穿刺模型建立与评价

Establishment and evaluation of a puncture model for vertebroplasty in rabbit vertebra

目的:通过对兔脊柱解剖形态的测量及分析,建立一种新的兔椎体成形术穿刺模型,并通过术后影像学及形态学分析,评估该模型建立方法的有效性和安全性。方法:选用26只健康新西兰兔(体重2.5~3.0kg),测量其中6只兔腰椎标本形态及其参数:L1~L7椎体高度、椎体基底宽度、椎间盘上缘距椎体最狭部距离、脊椎乳突垂直线距椎间盘上缘距离、脊椎副突下缘至椎体后缘距离,以明确兔椎体解剖特点,确定骨水泥注射的最佳位置、注射方向以及注射深度后对20只兔L5、L6椎体建立椎体成形术用穿刺模型。术后3d处死后行影像学及组织学切片检查,术后8周以及12周后分批处死行影像学检查,主要观测指标包括:手术时间,术后植入骨水泥分布,椎管及椎体前缘完整性。结果:通过兔解剖观测,椎体高度从L1~L5逐渐增大,从L5~L7逐渐减小,椎体基底部宽度从L1~L7逐渐增大。脊椎乳突中点和椎间盘上缘的距离由L1~L6逐渐增加(1.7~2.5mm)。脊柱副突下缘与椎管前壁距离由L1~L6逐渐增加(-0.2~1.3mm),相同节段每只兔脊椎乳突与椎间盘上缘(P=0.736)和副突与椎体后缘距离之间(P=0.611)无明显统计学差异。以脊椎乳突中点垂线与脊椎副突下缘水平线交点为穿刺点,置入方向和水平面呈20°~30°角,头倾方向0~10°,穿刺深度7~10mm可以构建兔椎体穿刺手术模型。术后未出现因脊髓损伤造成下肢瘫痪,1只兔因术后感染死亡,手术时间平均为40.8±5.9min(30~55min)。术后3d组织学检查示骨水泥材料植入骨小梁内,椎间盘及纤维环组织未见明显破坏。术后3d、8周及12周的Micro-CT三维重建均显示骨水泥在兔椎体松质骨内分布,新生骨组织包裹植入材料,无渗漏,无椎管及椎体前壁破损等并发症。结论:在兔腰椎解剖基础上,以脊椎乳突和副突为骨性标志,可以成功建立一种安全可靠的兔椎体成形术用穿刺模型。

Objectives:Through measuring and analyzing the anatomical shape of the rabbit spine,to explore the feasibility of establishing a puncture model for vertebroplasty in rabbit vertebra,and to clarify the method of model establishment.To evaluate the effectiveness and safety of this model through the imaging and morphological analysis after vertebroplasty.Methods:Twenty-six healthy New Zealand rabbits(body weight,2.5-3.0kg)were selected.The shape and parameters of spinal specimens of 6 rabbits were observed,including the length of the vertebral body,the width of the base of the vertebral body,the horizontal distance between the junction of the transverse process and the vertebral body,the intervertebral foramen,the anterior edge of the articular process and the upper edge of the intervertebral disc,and the distance between the upper edge of the intervertebral disc and the narrowest part of the vertebral body.The puncture model for vertebroplasty was established in the L5 and L6 vertebrae of 20 rabbits andα-Tricalcium phosphate bone cement was injected.Imaging and histological examination were performed 3 days,8 weeks,and 12 weeks after postoperative sacrifice.The main observation indexes included surgical duration,postoperative injection position of bone cement,and the integrity of the spinal canal and the anterior edge of the vertebral body.Results:According to the anatomical observation of the rabbits,the height of vertebrae increased gradually from L1 to L5 segments,and decreased gradually from L5 to L7 segments.The width of the base of the vertebrae increased gradually from L1 to L7 segments.The horizontal distance between the mammillary process and the upper edge of the intervertebral disc increased gradually from L1 to L6(1.7-2.5mm).The vertical distance between the posterior edge of the vertebrae and the inferior margin of anapophysis increased gradually from L1 to L6(-0.2-1.3mm).There was no statistical significance in the distance between the mammillary process and the upper edge of the intervertebral disc(P=0.736)and the distance between the posterior edge of the vertebrae and the inferior margin of anapophysis(P=0.611).The optimal entry point was set at the bisection of a vertical line through the mammillary process and a horizontal line through the inferior margin of anapophysis,with an angle of 20°-30°to the horizontal plane,head tilt of 0-10°and depth of insertion of 7-10mm.After vertebroplasty,no paralysis of lower limbs caused by spinal cord injury was found,and one rabbit died of infection.The average surgical duration was 40.8±5.9min(30-55min).The 3 days postoperative histological examination revealed new irregular bone and bone cement materials wrapped with bone trabecula.No disc or annulus fibrosus damage was found.3 days,8 weeks,and 12 weeks postoperative three-dimensional reconstruction based on Mirco-CT showed that the bone cement was distributed in the cancellous bone of the rabbit vertebral body with no cement leakage,and the vertebral canal and the anterior wall of the vertebral body were intact without damage.New bone tissue was found around the bone cement.Conclusions:Based on the anatomy of lumbar vertebrae,the puncture model for vertebroplasty in rabbit vertebra can be successfully established with the mamillary process and the anapophysis as bony landmarks.