自控微动带锁髓内钉内固定对骨折愈合影响的生物力学实验研究

THE INFLUENCE OF THE FIXATION WITH AUTO-CONTROL MICRO-MOTION LOCKING NAIL ON THE MODE OF FRACTURE HEALING

目的 探讨自控微动带锁髓内钉 (AMLN)固定后骨折局部生物力学环境对骨折愈合的影响及机制。方法 对 1 2只山羊两侧股骨干横断截骨 ,分别采用AMLN和Gross -Kempf(GK)钉内固定 ,术后 1、2、4、8周分批处死 ,测量骨的强度和刚度 ,不同愈合期的应力水平 ,愈合过程中的应力遮挡率 ,观察不同愈合期骨折愈合的宏观和微观生物力学机制。结果 ①AMLN固定后的压缩、弯曲和扭转强度均高于GK固定 ,强度达 3 0 %以上 ;②AMLN固定后的应力水平 7～ 8周时间基本达到原始骨骼的应力水平 ,比GK钉提前 4周左右 ;③AMLN固定后的应力遮挡率初期下降 40 % ,中期下降1 8% ,后期下降 1 6% ;结论 AMLN钉设计符合尚天裕教授提出的“弹性固定准则” ,器械与骨折远近端构成的几何不变体系坚强稳定 ,对断端的正常应力分布干扰小 ,骨折端间歇性动应力的产生与传导 ,较好地解决了应力遮挡与应力传导的平衡问题 ,骨折边愈合边改建边塑形 。

Objective To explore the influence of topical biomechanical environment in the fracture point after which was fixed with auto control micro motion locking nail (AMLN) on the fracture healing mode. Methods Twenty eight femoral shafts of fourteen sheep were fractured transversely and were fixed with AMLN or GK nails respectively. The animals were sacrificed at time point of one, two, four and eight weeks. The bony stiffness and intensity ,stress level in different fractural healing period and the rate of stress covered were measured. The mechanism of macro-and micro biomechanics in different fractural healing period were observed. Results ①The intensity of anti compression, anti flexion and anti-torsion in the fractural end after which fixed with AMLN is better than that fixed with GK nail. ② The stress level in the fractural end fixed with AMLN could recover completely at seven to eight weeks, which was four weeks earlier than GK nail fixation . ③ The rate of stress covered in the fractural end after which fixed with AMLN decline forty percent at initial stages, eighteen percent at metaphase and sixteen percent at advanced stage. Conclusion The design of AMLN accord with the guide line of plastic fixation. The geometry non anamorphosis which was constituted by the fixation set and the fractural far and near end was very firmly and settled. This fixation's disturbance to physical stress distribute in the fractural end was very lightly. AMLN fixation of fracture could resolve the balanced question between the stress conduct and the stress protection, it also could make the fracture end healing better, and make the fractural healing process speed up.