Miramini Saeed, Zhang Lihai, Richardson Martin, Mendis Priyan, Oloyede Adekunle, Ebeling Peter
Department of Infrastructure Engineering, The University of Melbourne, Parkville, VIC, 3010, Australia.
The Epworth Hospital, Richmond, VIC, 3121, Australia.
Australas Phys Eng Sci Med. 2016 Mar;39(1):123-33. doi: 10.1007/s13246-015-0407-9. Epub 2015 Dec 3.
Interfragmentary movement (IFM) at the fracture site plays an important role in fracture healing, particularly during its early stage, via influencing the mechanical microenvironment of mesenchymal stem cells within the fracture callus. However, the effect of changes in IFM resulting from the changes in the configuration of locking plate fixation on cell differentiation has not yet been fully understood. In this study, mechanical experiments on surrogate tibia specimens, manufactured from specially formulated polyurethane, were conducted to investigate changes in IFM of fractures under various locking plate fixation configurations and loading magnitudes. The effect of the observed IFM on callus cell differentiation was then further studied using computational simulation. We found that during the early stage, cell differentiation in the fracture callus is highly influenced by fracture gap size and IFM, which in turn, is highly sensitive to locking plate fixation configuration. The computational model predicted that a small gap size (e.g. 1 mm) under a relatively flexible configuration of locking plate fixation (larger bone-plate distances and working lengths) could experience excessive strain and fluid flow within the fracture site, resulting in excessive fibrous tissue differentiation and delayed healing. By contrast, a relatively flexible configuration of locking plate fixation was predicted to improve cartilaginous callus formation and bone healing for a relatively larger gap size (e.g. 3 mm). If further confirmed by animal and human studies, the research outcome of this paper may have implications for orthopaedic surgeons in optimising the application of locking plate fixations for fractures in clinical practice.
骨折部位的骨折块间移动（IFM）在骨折愈合中起着重要作用，尤其是在早期阶段，它通过影响骨折痂内间充质干细胞的力学微环境来实现。然而，锁定钢板固定构型变化所导致的IFM改变对细胞分化的影响尚未完全明确。在本研究中，对由特殊配方聚氨酯制成的替代胫骨标本进行力学实验，以研究在各种锁定钢板固定构型和加载幅度下骨折的IFM变化。然后使用计算模拟进一步研究观察到的IFM对骨痂细胞分化的影响。我们发现，在早期阶段，骨折痂内的细胞分化受骨折间隙大小和IFM的高度影响，而IFM又对锁定钢板固定构型高度敏感。计算模型预测，在锁定钢板固定相对灵活的构型（较大的骨板距离和工作长度）下，较小的间隙尺寸（如1毫米）可能会在骨折部位经历过度应变和流体流动，导致过多的纤维组织分化和愈合延迟。相比之下，对于相对较大的间隙尺寸（如3毫米），预测锁定钢板固定相对灵活的构型可改善软骨痂形成和骨愈合。如果通过动物和人体研究进一步证实，本文的研究结果可能会对骨科医生在临床实践中优化锁定钢板固定治疗骨折的应用产生影响。
