交锁钉与加压钢板固定尺骨骨折的生物力学比较

Evaluation of interlocking intramedullary nails and dynamic compression plate for the fixation of ulnar fracture:a comparative study of their biomechanical properties

[目的]对交锁髓内钉与动力加压钢板固定尺骨骨折的生物力学性能进行测试,为临床应用提供理论依据。[方法]采用12根新鲜尺骨标本,制作成中段横形骨折模型,分别用交锁髓内钉和6孔3.5mm动力加压钢板固定,髓内钉规格为4mm,长200～230mm。将标本固定于MTS试验机,对其进行抗轴向压缩、抗弯曲、抗扭转的生物力学测试,比较分析抗压刚度、抗弯刚度、抗扭刚度和抗压强度、抗弯强度、抗扭强度。[结果]交锁髓内钉固定的抗轴向压缩刚度、抗弯曲刚度和抗扭转刚度依次为(450.00±38.42)N/mm、(45.64±5.24)N.cm/Deg、(11.42±1.21)N.cm/Deg;6孔3.5mm动力加压钢板固定的抗轴向压缩刚度、抗弯曲刚度和抗扭转刚度分别为(405.40±29.26)N/mm、(41.00±4.78)N.cm/Deg、(10.05±1.32)N.cm/Deg。在1000N轴向压缩载荷作用下,交锁髓内钉和加压钢板固定时尺骨的位移分别为(2.20±0.11)mm和(2.48±0.15)mm;在5N.m弯曲载荷下,采用交锁髓内钉固定的尺骨的最大桡度为(3.25±0.15)mm,加压钢板固定的最大桡度为(3.60±0.21)mm;在扭转试验中,交锁髓内钉固定能承受扭矩最大达(2.40±0.13)N.m,而加压钢板固定能承受的扭矩为(1.90±0.10)N.m;实验所得的数据采用SPSS.10软件处理,再进行t检验显示具有显著性差异(P<0.05)。可见交锁髓内钉在力学刚度和强度上均优于6孔3.5mm动力加压钢板固定。[结论]交锁髓内钉具有良好的生物力学性能,固定可靠,符合生物学固定的原则。

[ Objective] Ulnar fractures fixed by interlocking intramedullary nails or dynamic compression plates were tested to compare their biomechanical function,in order to provide the theoretical basis for clinical practice. [ Method ] In the experiment, 12 pieces of fresh ulnars were used to produce middle-part transverse fracture models;which were fixed by interlocking intr- amedullary nails or six-hole 3.5 mm dynamic compression plates seperately. The diameter of intramedullary nail was 4mm, and the length was 200 - 230mm. The specimen was set on the MTS test machine. The rigidity and strength of ulnar fractures fixed by interlocking intramedullary nails were compared with those of ulnar fractures fixed by six-hole 3.5 mm dynamic compression plates in the anti-axial test, anti-bending test, anti-torsional test. [ Result] In the anti-axial test, anti-bending test and anti-torsional test, the rigidity of ulnar fractures fixed by interlocking intramedullary nails was 450.00±38.42 N/mm ,45.64±5.24 N ·cm/Deg, 11.42 ±1.21N·cm/Deg in sequence;while the rigidity fixed by dynamic compression plates was 405.40±29.26 N/mm ,41.00 ＋4.78 N·cm/Deg,10.05±1.32 N ·cm/Deg accordingly. Burdened 1000N axial pressure,the displacement of interlocking intramedullay nail fixing specimen was 2.20±0.11 mm,and the compression plate fixing specimen was 2.48±0.15 mm. Given a 5 N·M bending burden, the maximum radial bending degree of interlocking intramedullay nailfixing specimen was 3.25±0. 15 mm, which was 3.60±0.21 mm of compression plate fixing specimen. In the anti-torsional test, the interlocking intramedullay nail and compression plate fixing specimen could burden 2.40±0. 13 N ·M and 1.90±0.10 N·M respectively. The experimental data were analyzed by software SPSS. 10, which came to a distinguished difference by t-test（ P 〈 0.05 ）. Not only on the anti-axial rigidity, anti-bending rigidity and anti-torsional rigidity, but also on the anti-axiai strength,anti-bending strength and antitorsional strength,interlocking intramedullay nails were superior to dynamic compression plates. [ Conclusion ] The inter-locking intramedullary nails has fine biomechanical characteristics and is able to provide firm fixation Ibr ulnar fiactures,which fit the principles of biological osteosynthesis.