Experimental Study To Evaluate Novel Porous Bioactive Glasses For Lacunar Bone Defects Repair

There are several reasons can lead to bone defects, such as severe fractures, chronicosteomyelitis, bone tumors and so on. A small piece of bone defects can be healed byautologous bone graft, however the repair of massive bone defects is still a difficultproblem to orthopedics surgeon. The complications of allograft, such as nonunion,fracture, and infectious diseases limit its wide applications. Bone graft substitute has beenstudied and applied extensively in recent years. Bioactive glass is a novel bone graftsubstitute which not only has good biocompatibility and biodegradability but also have thegood biological activity. Once the bioactive glass contact with human tissue liquid, aseries of intracellular and extracellular reaction will occur, and a silicon-rich layer and ahydroxyapatite layer will be formed at the surface of the material. The localmicro-environment will be helpful to the osteoblast adhesion and will promote the boneformation.Objective: To evaluate the biocompatibility, biological activity, as well as the biode-gradability of novel porous bioactive glass in sheep lacunar bone defects repair.Traditional bioactive glass is the control group in this study. Methods: L3-L5vertebrae of12adult sheep were established8mm×15mm lacunarbone defects model, the experimental groups were MPS and INJ, and the control groupwas NBP. According to a randomized block design, three of every sheep vertebral defectswere filled with NBP, MPS and INJ respectively. Each animal received all three treatments.Specimens were examined after6and12weeks; The biocompatibility, biological activity,as well as the biodegradability were evaluated by post-surgical appearance, grossobservation, X-ray radiograph Micro-CT3D reconstruction and histological examination.Results:①There was no abnormal appearance of all the sheep. All incisions werehealed.②General observation found no graft leakage or any abnormal connective tissuemass.③After6and12weeks, the Lane-Sandhu X-ray scores of MPS group and INJgroup were higher than the NBP group (p <0.05). Score of MPS group is equal to INJgroup.④Micro-CT3D reconstruction shows that the materials of MPS group and INJgroup are tightly integrated with the host bone. There is no obvious boundary betweenthem. However, materials of NBP group and the host bone have clear boundary.⑤After6and12weeks, sheep in the MPS group and INJ group had better osteogenesisability than that in the NBP group (p<0.05), and of which MPS group was similar to INJgroup (p>0.05). Compared with12weeks group, the bone formation of all the threematerials increased significantly in6weeks group (p<0.01). With the passage of time, allthe three materials were significantly degraded.Conclusions:①Both the morphological parameters, the bone density, and thebiomechanical data of sheep lumbar lacunar bone defect model is similar to that of humanbeings.So the sheep model has a certain degree of reliability.②All three types of bioactiveglass have excellent biocompatibility. Both MPS and INJ have better biocompatibility,biological activity, as well as the biodegradability than NBP.③INJ which pore size is500～1000μm has shown better osteogenesis than MPS which pore size is2000～3000μm.