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膨胀套管在骨质疏松模块中生物力学测试

Bone Biomechanics of Pedicle Screw with Expansion Sleeve in Osteoporotic Synthetic Bone Block

【作者】 韩晓辉

【导师】 韩永台;

【作者基本信息】 河北医科大学 , 外科学, 2014, 硕士

【摘要】 目的:骨质疏松症是以骨量减少,骨小梁结构破坏,骨强度下降,骨脆性增加为特点的全身性代谢疾病,骨质疏松的特征为容易发生骨折,轻微外力可以导致严重的骨折,因为缺乏坚强的骨支撑,无法得到坚固的内固定,术后内固定失败率高,使得骨折后的处理非常棘手,并且效果往往不满意,针对如何提高骨质疏松患者内固定的稳定性,有学者进行了研究探索,取得了很大的进步,同时也存在一些不足。针对这些不足之处,我们课题组设计并研制了新型可吸收膨胀套管,进行了相关力学实验,通过测试并比较普通椎弓根螺钉加用自行设计的膨胀套管与单纯普通螺钉(conventional pedicle screw CPS)在骨质疏松实验模块中的最大轴向拔出力、旋出扭力和侧方压力,评价膨胀套管在增强椎弓根螺钉的稳定性的作用。方法:随机选取60枚型号、大小均一致的普通椎弓根螺钉(均由厦门大博医疗公司提供)随机分为两组,每组30个,其中一组加用可吸收膨胀套管为实验组,另外一组为单纯普通螺钉作为对照组,30块标准骨质疏松生物力学实验模块,模块的标准一致,大小,形状一致,排除因材料型号,尺寸的不同带来的误差。采用相同的方法分别在每块模块上制备2个钉道,其中一个钉道先拧入膨胀套管,再从套管中央空腔拧入螺钉,使套管尖端膨胀开,形成“三角形”结构,对照组直接垂直拧入普通椎弓根螺钉。对所有标本进行X线检查,确定膨胀套管完全膨胀开,然后通过生物力学试验机行轴向拔出、最大旋出扭力和侧方压力实验,通过计算机记录实验数据。比较实验组与对照组最大轴向拔出力(Fmax)、最大旋出力矩和侧方压力情况。结果:X线检查显示,2组中的椎弓根螺钉均被周围PU材料紧密包绕,带膨胀套管的椎弓根螺钉前端在模块中膨胀形成类似“三角形”的结构,螺钉上下垂直,排除螺钉倾斜带来的误差。通过比较最大轴向拔出力,最大旋出力和最大侧方压力来比较实验组和对照组之间的差异。测得螺钉轴向拔出力(Fmax)实验组(396.43±49.91)N、对照组(347.62±23.72)N,t=-5.973,p=0.002,按照α=0.05检验水准,P<0.05;最大旋出力矩(Nm)实验组(3.41±0.82)Nm、对照组(1.86±0.41)Nm,t=-3.501,P=0.017,按照α=0.05检验水准,P<0.05;侧方压力:实验组(25.06±3.15)N、对照组:(22.13±2.15)N,t=7.925,P<0.001,实验组最大轴向拔出力及最大旋出力矩和侧方压力均大于对照组,差异有统计学意义。结论:对于需要行脊柱内固定手术的骨质疏松患者,在普通螺钉的基础上加用膨胀套管,操作简单,不增加手术时间和出血量,能够增强螺钉的稳定性,术后取钉方便,简单。普通螺钉加用可吸收膨胀套管可以提高螺钉在骨质疏松生物力学模块中的稳定性,能够避免了普通膨胀螺钉术后取钉困难、断钉等问题,有广阔的应用前景。

【Abstract】 Objective: Osteoporosis sickness is systemic metabolic diseasecharacterized by bone loss, trabecular crack, bone density drop, andsubsequent predispose to severe fracture. In spinal surgery, cause ofosteoporosis,postoperative internal fixation failure rate is relatively high, andprognosis of secondary surgeries are often not satisfied. In order to improvethe stability of the internal fixation in osteoporosis patients, scholars put outmany methods, and have got great progress, but still with some deficiencies.In our research, based on the deficiencies, we designed developed absorbedexpansion sleeve, and to compare the maximum axial pullout of pedicle screwwith expansion sleeve with conventional pedicle screw in osteoporoticsynthetic bone block, evaluate the stability of pedicle screw with expansionsleeve.Methods:60pieces of conventional pedicle screws (Double medicalmaterials co. LTD, Xiamen)were randomly divided into two groupsaverage.One group with expansion sleeve regarded as the experimental group, whileconventional pedicle screw(CPS) as control group. In30osteoporoticsynthetic bone block of consistent standards, pilot holes were prepared inadvance using the same method in all samples. In one pilot holes,verticallyimplant expansion sleeve and screw, make sure the expansion sleeve anchoredtightly by X-ray photography, the other one implant CPS. Compare maximumaxial pullout (Fmax), maximum running torque, lateral pressure between theexperimental group and control group by biomechanical test-machine.Result: The screw was surrounded directly by polyurethane material, theexpansion sleeve anchored tightly in X-ray examination. Screw is vertical toeliminate the error of incline. Fmax: the experimental group (396.43±49.91)N, control group (347.62±23.72) N, t=-5.973,p=0.002.Maximum running torque: the experimental group (3.41±0.82) Nm, control group(1.86±0.41)Nm,t=-3.501,P=0.017. Lateral pressure: the experimental group(25.06±3.15)N, control group(22.13±2.15)N, t=7.925,P<0.001.According toα=0.05, significant level, P<0.05.the Fmax, maximum runningtorque and lateral pressure of the experimental group were greater than controlgroup with statistically difference.Conclusion: In spinal implant operation of osteoporosis patients, CPSwith expansion sleeve is more stable than CPS without operation timeprolonged and bleeding increased, and is easy to withdraw the internalfixation. CPS with expansion sleeve has widely application prospect withcharacters of improving the stability of screw in the osteoporotic syntheticbone block and avoiding looseness or breakage of internal fixation.

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