Computational Analysis of Large Bone Defect Healing Using Bone Tissue Scaffolds, Degradation, and Growth Factor Delivery: A Mechanobiological Model of Bone Tissue Formation

Large bone defects are a significant medical challenge. 3D printed synthetic biocompatible and biodegradable bone tissue scaffolds offer a possible clinical solution. Degradability of these bone scaffolds within the body precludes the need for additional interventions allowing native bone to replace the implant during healing. Degradation rates can be altered by chemical composition but the optimal design of these rates to maximize bone growth is unknown. Many researchers have conducted experiments on degradation, but this is time consuming and difficult to measure particularly in vivo. Mechanobiological models to evaluate degradation and bone healing for bone tissue scaffolds would be an attractive option to design bone tissue scaffold degradation but these are not widely available. This study aims to model both bone healing and scaffold degradation for a bone tissue scaffold integrating agent-based modelling and finite element analysis (FEA). It introduces an innovative computational method to examine the effects of scaffold degradation rates (slow, medium, and fast) and the incorporation of embedded bone morphogenetic proteins (BMPs) on bone regeneration. The results indicated that scaffold degradation at a medium rate of 6% volume reduction per day resulted in the greatest volume of regenerated bone by 18.2 mm3, in contrast to slow and fast degradation by 16.4 mm3 and 18.1 mm3, respectively. The case using medium scaffold degradation with embedded BMPs enhanced bone regeneration, resulting in a further increase of 2 mm3 of bone volume. Further work is planned to calibrate the model and to apply these techniques to optimize bone tissue scaffold designs.