The relationship between interfragmentary movement and cell differentiation in early fracture healing under locking plate fixation
- 498 Downloads
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.
KeywordsFracture healing Mesenchymal stem cell differentiation Locking plate fixation Mechanical testing Computational simulation Osteoporosis
The authors would like to thank AOTRAUMA Asia Pacific (AOTAP14-02), DePuy Synthes, Victorian Orthopaedic Research Trust (2014–2015), Epworth HealthCare and the University of Melbourne for their support.
- 30.Döbele S, Horn C, Eichhorn S, Buchholtz A, Lenich A, Burgkart R, Nüssler AK, Lucke M, Andermatt D, Koch R (2010) The dynamic locking screw (DLS) can increase interfragmentary motion on the near cortex of locked plating constructs by reducing the axial stiffness. Langenbeck’s Arch Surg 395(4):421–428CrossRefGoogle Scholar
- 31.Amano R, Sundén B (2011) Computational fluid dynamics and heat transfer: emerging topics, vol 23. WIT Press, BillericaGoogle Scholar
- 32.Fazi G, Tellini S, Vangi D, Branchi R (2010) Three-dimensional finite element analysis of different implant configurations for a mandibular fixed prosthesis. Int J Oral Maxillofac Implant 26(4):752–759Google Scholar
- 33.Cepeda J, Birla S, Subbiah J, Thippareddi HA (2013) Practical method to model complex three-dimensional geometries with non-uniform material properties using image-based design and COMSOL Multiphysics®. In: COMSOL conference, BostonGoogle Scholar
- 34.Mimics (2011). vol 14.11. Materialise, Haasrode, BelgiumGoogle Scholar