用于治疗下胫腓联合损伤不同材质螺钉的生物力学研究

Biomechanical study on screws with different materials for treatment of distal tibiofibular syndesmosis injury

目的探讨镁合金螺钉及羟基磷灰石涂层镁合金螺钉在治疗下胫腓联合损伤时在力学特性上是否与钛合金螺钉存在差异。方法参照市售治疗下胫腓联合损伤的钛合金螺钉制作相同规格的镁合金螺钉及羟基磷灰石涂层镁合金螺钉,取3种不同材质的螺钉(镁合金螺钉、羟基磷灰石涂层镁合金螺钉和钛合金螺钉),分成3组,即镁合金螺钉组、羟基磷灰石涂层镁合金螺钉组(简称羟基磷灰石涂层组)和钛合金螺钉组。将3种不同材质同种规格(直径2.7 mm×长30.0 mm、直径3.5 mm×长45.0 mm、直径4.5 mm×长45.0 mm)的螺钉分别进行最大扭矩和断裂扭转角实验、轴向拔出力实验、旋动扭矩(旋入、旋出)实验。结果最大扭矩和断裂扭转角实验:镁合金螺钉及羟基磷灰石涂层镁合金螺钉的最大扭矩小于钛合金螺钉,差异有显著统计学意义(2.7 mm×30.0 mm:镁合金螺钉组0.28 N·m±0.01 N·m,羟基磷灰石涂层组0.30 N·m±0.02 N·m,钛合金螺钉组1.39 N·m±0.01 N·m。H=20.607,P=0.000<0.01。3.5 mm×45.0 mm:镁合金螺钉组0.63 N·m±0.03 N·m,羟基磷灰石涂层组0.66 N·m±0.03 N·m,钛合金螺钉组2.81 N·m±0.05 N·m。F=11738.224,P=0.000<0.01。4.5 mm×45.0 mm:镁合金螺钉组1.16 N·m±0.02 N·m,羟基磷灰石涂层组1.16 N·m±0.04 N·m,钛合金螺钉组5.52 N·m±0.07 N·m。F=29111.916,P=0.000<0.01);而最大断裂扭转角在螺钉直径为2.7 mm时,差异无统计学意义(2.7 mm×30.0 mm:镁合金螺钉组221.20°±7.67°,羟基磷灰石涂层组224.39°±8.30°,钛合金螺钉组224.70°±1.95°。H=0.863,P=0.649>0.05);而当螺钉直径增加至3.5 mm、4.5 mm时,扭转角明显小于钛合金组,差异有显著统计学意义(3.5 mm×45.0 mm:镁合金螺钉组125.00°±11.60°,羟基磷灰石涂层组128.00°±3.30°,钛合金螺钉组138.20°±4.73°。H=20.979,P=0.000<0.01。4.5 mm×45.0 mm:镁合金螺钉组135.00°±6.68°,羟基磷灰石涂层组134.90°±2.85°,钛合金螺钉组185.30°±13.53°。H=19.560,P=0.000<0.01)。轴向拔出力实验:镁合金螺钉和羟基磷灰石涂层镁合金螺钉轴向拔出实验最大载荷与钛合金螺钉轴向拔出实验最大载荷基本相当,差异无统计学意义(2.7 mm×30.0 mm:镁合金螺钉组297.40 N±17.80 N,羟基磷灰石涂层组291.40 N±7.11 N,钛合金螺钉组297.50 N±8.96 N。H=3.248,P=0.197>0.05。3.5 mm×45.0 mm:镁合金螺钉组364.30 N±23.34 N,羟基磷灰石涂层组358.20 N±8.84 N,钛合金螺钉组364.70 N±23.69 N。F=0.336,P=0.717>0.05。4.5 mm×45.0 mm:镁合金螺钉组475.60 N±39.37 N,羟基磷灰石涂层组469.70 N±23.24 N,钛合金螺钉组490.30 N±8.62 N。H=4.197,P=0.123>0.05),失效方式均为材料失效。旋动扭矩(旋入、旋出)实验:镁合金螺钉和羟基磷灰石涂层镁合金螺钉旋入扭矩、旋出扭矩与钛合金螺钉旋入扭矩、旋出扭矩基本相当,差异无统计学意义(旋入实验,2.7 mm×30.0 mm:镁合金螺钉组0.07 N·m±0.01 N·m,羟基磷灰石涂层组0.08 N·m±0.01 N·m,钛合金螺钉组0.08 N·m±0.01 N·m。F=0.617,P=0.547>0.05。3.5 mm×45.0 mm:镁合金螺钉组0.15 N·m±0.02 N·m,羟基磷灰石涂层组0.08 N·m±0.01 N·m,钛合金螺钉组0.08 N·m±0.02 N·m。F=0.559,P=0.578>0.05。4.5 mm×45.0 mm:镁合金螺钉组0.27 N·m±0.01 N·m,羟基磷灰石涂层组0.27 N·m±0.02 N·m,钛合金螺钉组0.27 N·m±0.03 N·m。H=3.142,P=0.208>0.05。旋出实验,2.7 mm×30.0 mm:镁合金螺钉组0.06 N·m±0.01 N·m,羟基磷灰石涂层组0.06 N·m±0.01 N·m,钛合金螺钉组0.06 N·m±0.01 N·m。F=0.368,P=0.696>0.05。3.5 mm×45.0 mm:镁合金螺钉组0.12 N·m±0.02 N·m,羟基磷灰石涂层组0.13 N·m±0.02 N·m,钛合金螺钉组0.11 N·m±0.02 N·m。F=1.429,P=0.257>0.05。4.5 mm×45.0 mm:镁合金螺钉组0.20 N·m±0.02 N·m,羟基磷灰石涂层组0.20 N·m±0.01 N·m,钛合金螺钉组0.18 N·m±0.04 N·m。H=2.653,P=0.268>0.05)。结论镁合金螺钉和羟基磷灰石涂层镁合金螺钉与钛合金螺钉在最大扭矩和断裂扭转角之间有差异,但这并不影响在实际当中的应用。在轴向拔出和旋入与旋出扭矩之间均无明显差异,可以认为镁合金螺钉和羟基磷灰石涂层镁合金螺钉作为骨科植入物在治疗下胫腓联合损伤时可以达到与钛合金螺钉相同的固定效果,且镁合金螺钉及羟基磷灰石涂层镁合金螺钉的可降解性、与骨更相近的弹性模量及还可进一步促进骨折的愈合使其在治疗下胫腓联合损伤更具有优越性。

Objective To investigate whether the mechanical properties of magnesium alloy screws and hydroxyapatite coated magnesium alloy screws are different from those of titanium alloy screws in the treatment of lower tibiofibular joint injuries.Methods The commercially available titanium alloy screw used for treatment of lower inferior tibiofibular syndesmosis was taken as referenced,magnesium alloy screws and hydroxyapatite-coated magnesium alloy screw with the same specifications were made.Three screws of different materials were divided into 3 groups,which were magnesium alloy screw group,hydroxyapatite-coated magnesium alloy screw group(hydroxyapatite-coated group)and titanium alloy screw group.The 3 groups of screw with the same specifications(diameter 2.7 mm×length 30.0 mm,diameter 3.5 mm×length 45.0 mm,diameter 4.5 mm×length 45.0 mm)were performed maximum torque and fracture torsion angle experiments,axial pullout force experiment and rotation torque(screw,unscrew)experiment.Results The maximum torque and fracture torsion angle experiment:the maximum torque of magnesium alloy screw group and hydroxyapatite-coated magnesium alloy screw group was significantly lower than that of titanium alloy screw group(2.7 mm×30.0 mm:magnesium alloy screw group 0.28 N·m±0.01 N·m,hydroxyapatite-coated group 0.30 N·m±0.02 N·m,titanium alloy screw group 1.39 N·m±0.01 N·m.H=20.607,P=0.000<0.01.3.5 mm×45.0 mm:magnesium alloy screw group0.63 N·m±0.03 N·m,hydroxyapatite-coated group 0.66 N·m±0.03 N·m,titanium alloy screw group 2.81 N·m±0.05 N·m.F=11738.224,P=0.000<0.01.4.5 mm×45.0 mm:magnesium alloy screw group 1.16 N·m±0.02 N·m,hydroxyapatite-coated group 1.16 N·m±0.04 N·m,titanium alloy screw group 5.52 N·m±0.07 N·m.F=29111.916,P=0.000<0.01).There was no significant difference in the maximum fracture torsion angle of screw diameter with 2.7 mm(2.7 mm×30.0 mm:magnesium alloy screw group 221.20°±7.67°,hydroxyapatite-coated group 224.39°±8.30°,titanium alloy screw group 224.70°±1.95°.H=0.863,P=0.649>0.05).When screw diameters increased to 3.5 mm and 4.5 mm,the torsion angles were significantly smaller than those of titanium alloy group,and the differences were statistically significant(3.5 mm×45.0 mm:magnesium alloy screw group 125.00°±11.60°,hydroxyapatite-coated group 128.00°±3.30°,titanium alloy screw group 138.20°±4.73°.H=20.979,P=0.000<0.05.4.5 mm×45.0 mm:magnesium alloy screw group 135.00°±6.68°,hydroxyapatite-coated group 134.90°±2.85°,titanium alloy screw group 185.30°±13.53°.H=19.560,P=0.000<0.01).The axial pullout force experiment:the maximum loads of 3 groups were basically the same,and the difference was no statistically significant(2.7 mm×30.0 mm:magnesium alloy screw group 297.40 N±17.80 N,hydroxyapatite-coated group 291.40 N±7.11 N,titanium alloy screw group 297.50 N±8.96 N.H=3.248,P=0.197>0.05.3.5 mm×45.0 mm:magnesium alloy screw group 364.30 N±23.34 N,hydroxyapatite-coated group358.20 N±8.84 N,titanium alloy screw group 364.70 N±23.69 N.F=0.336,P=0.717>0.05.4.5 mm×45.0 mm:magnesium alloy screw group 475.60 N±39.37 N,hydroxyapatite-coated group 469.70 N±23.24 N,titanium alloy screw group 490.30 N±8.62 N.H=4.197,P=0.123>0.05),and the failure modes were all material failure.The rotation torque(screw,unscrew)experiment:the screw torque and unscrew torque of 3 groups were basically the same,and the difference was no statistically significant(screw experiment,2.7 mm×30.0 mm:magnesium alloy screw group 0.07 N·m±0.01 N·m,hydroxyapatite-coated group0.08 N·m±0.01 N·m,titanium alloy screw group 0.08 N·m±0.01 N·m.F=0.617,P=0.547>0.05.3.5 mm×45.0 mm:magnesium alloy screw group 0.15 N·m±0.02 N·m,hydroxyapatite-coated group 0.08 N·m±0.01 N·m,titanium alloy screw group0.08 N·m±0.02 N·m.F=0.559,P=0.578>0.05.4.5 mm×45.0 mm:magnesium alloy screw group 0.27 N·m±0.01 N·m,hydroxyapatite-coated group 0.27 N·m±0.02 N·m,titanium alloy screw group 0.27 N·m±0.03 N·m,H=3.142,P=0.208>0.05.Unscrew experiment,2.7 mm×30.0 mm:magnesium alloy screw group 0.06 N·m±0.01 N·m,hydroxyapatite-coated group0.06 N·m±0.01 N·m,titanium alloy screw group 0.06 N·m±0.01 N·m.F=0.368,P=0.696>0.05.3.5 mm×45.0 mm:magnesium alloy screw group 0.12 N·m±0.02 N·m,hydroxyapatite-coated group 0.13 N·m±0.02 N·m,titanium alloy screw group0.11 N·m±0.02 N·m.F=1.429,P=0.257>0.05.4.5 mm×45.0 mm:magnesium alloy screw group 0.20 N·m±0.02 N·m,hydroxyapatite-coated group 0.20 N·m±0.01 N·m,titanium alloy screw group 0.18 N·m±0.04 N·m.H=2.653,P=0.268>0.05).Conclusion It is demonstrated that magnesium alloy screw,hydroxyapatite-coated magnesium alloy screw and titanium alloy screw have differences in maximum torque and fracture torsion angle,which does not affect practical application.There is no significant difference between axial pullout,screw and unscrew torque.The magnesium alloy screw and hydroxyapatite-coated magnesium alloy screw as orthopedic implants can achieve the same fixation effect as titanium alloy screw in treatment of lower tibiofibular syndesmosis injury,and magnesium alloy screw and hydroxyapatite-coated magnesium alloy screw have more advantages in treatment of tibiofibular syndesmosis injury due to the biodegradability,similar elastic modulus to that of bone and the feature of preferably promoting fracture healing.