Preparation Of A Film-Reinforced 45S5 Bioactive Glass Bone Scaffold And Numerical Studies On The Coupling Process Of The Scaffold Degradation And Bone Remodeling

Bone disease is common in orthopedics,although it does not immediately endanger patients,it seriously affects their quality of life.Bone defect is a kind of bone disease caused by trauma,immunity,etc.Bone scaffold,as one of the key factors in repairing the bone defect,should be porous,biocompatible,biodegradable,and of course,enough mechanical support.Addressing the45S5 bioactive glass which has nice osteoconductivity and osteoinductivity but low mechanical strength,referring to the strengthening way of the fiber-reinforced concrete,the 45S5 bone scaffold was wrapped by poly caprolactone(PCL)/polyethylene glycol(PEG)film in order to improve its compressive strength.Meanwhile,considering the biodegradability of scaffold,separate theoretical frameworks to numerically simulate the degradation of both bioactive glass and polymer were proposed.Moreover,the coupling process of the scaffold degradation and bone formation during the bone repair process was discussed.Three parts are mainly involved in the dissertation:1.In order to improve the compressive strength of the 45S5 bioglass scaffold,an electrospun PCL/PEG film was used to wrap the 45S5 scaffold.After characterization of the film by morphology,contact angle,and the porosity,the results indicated that the porous film exhibited high hydrophilicity.Moreover,the compressive test on the film-wrapped scaffold showed that its compressive strength was greatly improved to 1.6 MPa,which is five times of that for the unwrapped 45S5 scaffold.2.According to the 5-step degradation mechanism of the bioactive glass,a degradation mathematical model for the 45S5 bioglass was proposed.Through comparing with the experimental data the corresponding parameters were get.Moreover,the bone remodeling regulated by a function of the mechanical stimulation was also modeled.The dynamic coupling process of the 45S5 bioglass scaffold degradation and bone formation was numerically simulated,and the morphological and mechanical evolutions of the scaffod-bone system were analyzed.3.Considering the stochastical scission of molecular chains in polymer during hydrolysis and bone remodeling,a theoretical model of the coupled scaffold degradation and bone remodeling was proposed,and on the basis of the model,the effect of the mechanical stimulus on the coupling process in the dynamic bone repair was further studied.The results showed that under a same exercise duration,the volume of the newly-formed bone and the stiffness of the scaffold-bone system were improved as exercise intensity increases,while greater duration is not necessary to generate more bone under a same intensity.This dissertation provides a novel preparation method to improve the compressive strength of the bioglass scaffold.Meanwhile,the numerical study of the coupling scaffold degradation and bone remodeling under mechanical stimulus paves a theoretical way to select suitable scaffold materials and design scaffold structure,also it could be helpful to program the rehabilitation for the the treatment of bone defects.