新型骨水泥螺钉系统固定迟发性椎体骨折后骨坏死模型的生物力学评估

Biomechanical evaluation of Kummell’s disease model fixed with novel bone cement screw system

背景:创伤后椎体迟发性骨坏死(Kummell病)是一种特殊类型的骨质疏松性椎体骨折,于1891年被德国医生KUMMELL首次报道。目前使用骨水泥填充治疗后有较大概率会出现骨水泥松动移位等术后并发症。目的:采用生物力学分析方法探讨新型骨水泥螺钉联合椎体成形术治疗胸腰椎创伤致椎体迟发性骨坏死的效果。方法:获取30具羊脊柱标本,通过CT扫描检查保证所取标本没有椎体畸形。取T12-L2节段,在其L1节段制作创伤后椎体迟发性骨坏死椎体内裂隙模型,并对椎体内裂隙进行骨水泥强化治疗,随后按骨水泥填充方式的不同将标本随机分成单纯椎体成形术组、椎体成形术联合单侧椎弓根成形术组、椎体成形术联合双侧椎弓根成形术组、单侧新型骨水泥螺钉联合椎体成形术组、双侧新型骨水泥螺钉联合椎体成形术组(三维稳定性生物力学实验、最大轴向压力实验各5组)。所有标本术后均进行CT检查,判断螺钉位置是否理想以及椎体有无其他损伤情况,采用三维稳定性生物力学实验检测各组标本在前屈、后伸、左屈、右屈及左右轴向旋转6种运动状态下的骨水泥活动度,采用最大轴向压力实验检测骨水泥在受压时所能承受至出现骨水泥移位时的最大轴向压力。结果与结论:①所有标本术后影像学检查显示螺钉位置正常,未见新型骨水泥螺钉刺入椎管、稳定性欠佳等不良现象;②单、双侧新型骨水泥螺钉联合椎体成形术组在前屈、后伸、左屈和右屈运动状态下的骨水泥活动度均最小,具有更好的生物力学稳定性,这两组与其余3组相比较,差异有显著性意义(P<0.05),而此两组间的骨水泥活动度无显著差异(P>0.05),这提示单、双侧新型骨水泥螺钉均能达到相似的骨水泥稳定效果;③单、双侧新型骨水泥螺钉联合椎体成形术组具有较好的骨水泥受压能力,其骨水泥能够承受更大的轴向压力,具有更好的骨水泥稳定性,这两组与其余3组相比较,差异有显著性意义(P<0.05);双侧新型骨水泥螺钉联合椎体成形术组在垂直受力情况下所能承受压力最大,其次是单侧新型骨水泥螺钉联合椎体成形术组;④上述结果表明,新型骨水泥螺钉在胸腰椎创伤后椎体迟发性骨坏死治疗中能起到增加骨水泥稳定性及避免骨水泥松动移位的作用。

BACKGROUND:Delayed post-traumatic vertebral osteonecrosis(Kummell’s disease)is a special type of osteoporotic vertebral fracture,which was first reported by the German doctor Kummell in 1891.At present,there is a high probability of complications such as bone cement loosening and displacement after treatment with bone cement filling.OBJECTIVE:To analyze the biomechanical effect of new bone cement screw combined with vertebroplacty in the treatment of thoracolumbar Kummell’s disease.METHODS:Fifty sheep spine specimens were selected and scanned using computed tomography to ensure that the specimens had no vertebral deformity.All sheep spine segments from T12 to L2 were selected,and a Kummell’s disease intravertebral vacuum cleft model was made at the L1 segment,followed by treatment with bone cement augmentation.According to the ways of bone cement filling,the specimens were randomly divided into a vertebroplasty group,a vertebroplasty with unilateral pediculoplasty group,a vertebroplasty with bilateral pediculoplasty group,a unilateral bone cement screw with vertebroplasty group,and a bilateral bone cement screw with vertebroplasty group.There were five groups in each of the following experiments:three-dimensional stability biomechanics test and maximum axial compression test.All the specimens underwent postoperative computed tomography examination to determine whether the screw position was ideal and whether the vertebral body was damaged or not.In the three-dimensional stability biomechanics test,we measured the activity of bone cement in specimens under six motion states,including anteflexion,posterior extension,left flexion,right flexion,and left and right axial rotations.In the maximum axial pressure test,we detected the maximum axial pressure that the bone cement could withstand when it was under pressure until the bone cement was displaced.RESULTS AND CONCLUSION:Postoperative imaging examination of all specimens showed that all the screws were positioned normally,and there were no undesirable phenomena such as poor stability and inserting new bone cement screw into the spinal canal.The unilateral or bilateral bone cement screw with vertebroplasty groups had the smallest degree of mobility under the motion states of anteflexion,posterior extension,left and right flexion,and had better biomechanical stability,with a significant difference from the other three groups(P<0.05).However,there was no significant difference between the unilateral and bilateral novel bone cement screw with vertebroplasty groups(P>0.05).Therefore,unilateral and bilateral new cement screws could achieve similar cement stabilization effects.Compared with the other three groups,the unilateral and bilateral new bone cement screw with vertebroplasty groups had better compressive capacity of bone cement,in which the bone cement could withstand greater axial pressure and had better stability(P<0.05).The bilateral new bone cement screw with vertebroplasty group could bear the largest pressure under vertical force,followed by unilateral novel bone cement screw with vertebroplasty group.To conclude,the novel bone cement screw can increase the stability of bone cement and avoid the loosening and displacement of bone cement in the treatment of Kummell’s disease of the thoracolumbar spine.