下颌骨骨折坚固内固定应力遮挡的三维有限元分析

目的 :运用有限元法分析下颌骨功能状态下及坚固内固定时的应力分布 ,探讨可能发生的应力遮挡作用 ,为下颌骨骨折的治疗提供参考。方法 :对下颌骨体部骨折在骨愈合的不同时期及采用不同的内固定方法固定时的应力分布进行有限元法分析 ,计算各种工况下的应力遮挡率。结果 :骨折愈合的早期 ,单、双钢板固定时的应力遮挡率分别为98.90 %、99.63 % ,钛板为98.65%、99.58 % ;骨折愈合的中期 ,单、双钢板固定时的应力遮挡率分别为6.8%、22.96 % ,钛板为5.12 %、20.99 % ;骨折愈合的后期 ,单、双钢板固定时的应力遮挡率分别为5.73 %、14.14 % ,钛板为4.47 %、13.71 %。结论 :小型接骨板用于下颌骨体部骨折坚固内固定时 ,在骨折愈合的各个时期均存在明显的应力遮挡作用 ;钢板的应力遮挡作用大于钛板 ;接骨板固定位置的选择对骨断层的应力分布有重要的影响。

Three-dimensional finite element analysis of stress shielding effects of rigid internal fixation on mandibular fractures

Objective: To study stress the distribution during clenching and rigid internal fixation(RIF)of mandibular fractures.The stress shielding effects were also evaluated so as to provide reference optimizing rigid internal fixation design.Methods: The regularity of stress distribution of mandibular body fracture under different conditions were analysed during different period of bone healing. The value of stress shielding rate was used to represent the level of stress shielding effects.Results: When single and double steel miniplates were fixed respectively,the stress shielding rate were 98.90%, 99.63% and titanium miniplate 98.65% , 99.58% respectively during the earlier period of bone healing; the stress shielding rate of single and double steel miniplates were 6.8%, 22.96% and titanium miniplate 5.12%, 20.99% respectively during the middle period of bone healing; the stress shielding rate of single and double steel miniplates were 5.73%, 14.14% and titanium miniplate 4.47%,13.71% respectively during the later period of bone healing.Conclusion: The stress shielding effects definitely existed when miniplate rigid internal fixation system was chosen to treat mandibular body fractures. Stress shielding effects in the titanium-plated mandible are lower than that in the steel-plated mandible. The position of the plate also affected stress distribution of bone transverse section.