低弹性模量新型组合式锁定加压钢板固定股骨粉碎性骨折的生物力学研究

A new assembly of locking compression plate of low elastic modulus for fixation of femoral comminuted fractures： a biomechaulcal study

目的通过在尸体股骨上与传统普通锁定加压钢板（LCP）进行生物力学对比，探讨新研制出的低弹性模量新型组合式锁定加压钢板（NALCP）固定股骨粉碎性骨折应力及其分布。方法选取6对尸体股骨制成股骨中段粉碎性骨折，分别采用新研制出的低弹性模量NALCP（Ti2448，30gpa）和传统高弹性模量普通锁定加压钢板（Ti-6AL-4V，110Gpa）模拟手术固定，加以缓慢行走单腿股骨轴向加压载荷及扭转载荷，分别记录两组骨折块在X、Y、Z轴上的相对最大位移、钢板的最大应变及平均应变；制作出两组的应变分布云图；记录NALCP组轴向加载疲劳试验结果。结果轴向加压试验和扭转加载试验均显示NALCP组较LCP组主应变和平均应变更大，差异均有统计学意义（P〈0．05）。但两种钢板固定骨块在X、Y、Z轴上的相对最大位移比较差异均无统计学意义（P〉0．05）。两组钢板应变云图分布基本一致。NALCP组通过100万次的轴向循环载荷疲劳测试，NALCP完好，无形变、松动、断裂。结论低弹性模量NALCP能够有效固定骨块，并且有利于应力传导，更符合生物力学的要求，从而能够有效避免应力遮挡效应，促进骨折愈合。

Objective To compare the stress and its distribution between our self-designed new assembly of locking compression plate （NALCP） of low elastic modulus versus conventional locking compres- sion plate （LCP） in fixation of femoral comminuted fractures. Methods Six pairs of cadaveric femur were used to create models of middle femoral comminuted fracture. The femoral fracture models were fixated respectively by NALCP of Ti2448 with low elastic modulus （E = 30 Gpa） （NALCP group） and conventional LCP of Ti-6A1-4V with high elastic modulus （E = 110 Gpa） （LCP group）. Axial and torsion loads were applied on the models in the 2 groups to simulate those on one leg when a person slowly walks. The relative maximum displacements on the X, Y and Z axes of fracture fragments, and the maximum and average strains of the plate were recorded in the 2 groups. Nephograms of strain distribution were made for the 2 groups. The results of fatigue test under axial loads were recorded for NALCP group. Results Both the axial and torsion loading tests showed significantly larger principal and average strains in NACLP group than in LCP group （ P 〈 0. 05）. However, there were no significant differences between the 2 groups in the relative maximum displacements of fracture fragments on X, Y or Z axis （ P 〉 0. 05） . The plate strain nephograms for the 2 groups showed consistent strain distributions. The plates in NALCP group survived 1,000,000 fatigue tests under axial loads, without any deformation, loosening or breakage. Conclusion As our NALCP of low elastic modulus may be better in stress transmission and distribution, it can effectively reduce the effect of stress-shielding and promote bone healing.