a-氰基丙烯酸正辛酯反复粘接人胫骨皮质骨的生物力学研究

The Effect of Repeated Bonding of Octyl-a-cyanoacrylate Adhesive on Human Tibia Cortical Bone

在医用粘接胶固定骨折断端时,往往需要反复粘接固定才能达到满意的复位效果。本实验将新鲜人胫骨干复温后,于胫骨中段横断,取前方的皮质骨制成规则的三棱形,仔细处理断端骨面及三棱形的侧面,测量其面积后用于抗拉强度、剪切强度和弯曲强度的测定。在37℃生理盐水中用细砂纸打磨粘接面去除残余于骨面的胶体后,拭干各粘接面,再次测定抗拉、剪切、弯曲等指标,观察其变化。结果显示,第一次粘接的剪切强度大于第二次的剪切强度,二者之间有显著差异(P<0．05);第二次粘接的剪切强度大于第三次粘接的剪切强度,但无统计学显著差异(P>0．05);抗拉强度随粘接次数增加而减小,但各组之间无显著差异(P>0．05);在胶体断裂前,其弹性模量和刚度系数无显著差异(P>0．05)。在本实验中,初次粘接的抗拉强度为5．93 MPa,剪切强度为9．11 MPa,剪切实验中,被粘接的骨面的微形态结构的变化对剪切强度影响较大。在剪切强度的测定中,每次测定应去除1～2 mm的粘接面的骨质,以保证实验结果的可靠性。而拉伸试验和弯曲试验中,由于粘接面微形态结构的变化对实验结果无显著影响,去除骨面残留的胶体后即可进行反复实验。在临床操作中,对于剪切应力较大的部位,应一次粘接固定,以免反复粘接后影响粘接的固定效果。

During clinical operation, the repeated bonding of octyl-a-cyanoacrylate adhesive is necessary for staisfactory reduction and fixation. This is because the repeated bonding will change the morphologic characteristics of the bone surface in biomechanical study. The influence of repeated bonding of octyl-a- cyanoacrylate on fresh human tibia cortical bone was assessed in this experiment. First, we made the transverse fracture model on the anterior part of cortical bone of fresh human tibia shaft. After 24 hours of bonding, the tensile strength,shear strength and angular strength were tested; then we made the bonding for the second time and third time, tested the tensile strength, shear strength and angular strength respectively, and observed the change of tensile strength, shear strength and angular strength. We found the shear strength of the primary bonding being greater than that of the second bonding and the third bonding（P〈0.05）. The shear strength of the second bonding and the third bonding showed no statistically significant difference. The tensile strength, elastic modulus ,rigidity coefficient and moment of area inertia exhibited no statistically difference between the first ,second and third bonding. The repeated bonding of octyl-a-cyanoacrylate adhesive will change the morphologic characteristics of the bone surface, this will decrease the shear strength during the experiment. When the shear strength test is to be repeated, the residue of the adhesive on the surface of the bone bonded area should be removed. During clinical application, bonding should be performed only once in the area for resisting the shear strength.