Mechanically strong porous bioceramic tubes facilitate large segmental bone defect repair by providing long-term structurally stability and promoting osteogenesis

Mechanically strong magnesium-doped Ca-silicate bioceramic scaffolds have many advantages in repairing large segmental bone defects.Herein we combine β-TCP with 6 mol%magnesium-doped calcium silicate(Mg6)at three different ratios(TCP,TCP+15%Mg6,TCP+85%Mg6)to find an appropriate ratio which can exert considerable influence on bone regeneration.In this study,the bioceramic scaffolds were assessed for mechanical strength,bioactive ion release,biocompatibility,and osteogenic capacity through in vitro testing.Additionally,the potential for promoting bone regeneration was investigated through in vivo implantation of porous tube-like scaffolds.The results showed that the compressive strength increased with the augmentation of Mg6 component.Especially the compressive strength of the TCP+85%Mg6 group reached 38.1±3.8 MPa,three times that of the other two groups.Furthermore,extensive in vivo investigations revealed that the TCP+85%Mg6 bioceramic scaffolds were particularly beneficial for the osteogenic capacity of critical-sized femoral defects(20 mm in length).Altogether,magnesium doping in bioceramic implants is a promising strategy to provide stronger mechanical support and enhance osteogenesis to accelerate the repair of large defects.

Research on Construction Process of Steel Box Girder Bridge and Its Stress Analysis

The paper introduce the construction method of large segment hosting and its difficulty, and drawing up corresponding liner and stress monitoring plan. The paper gives the calculation method of shear area for such a big cantilever thin-walled steel box girder section, namely the shear coefficient computation theory of Professor Hu Haichang, and the use of this shear area perfect beam element model, structure model and the experiment prove that the shell model is more consistent, given a certain reference for similar section project.

Electroactive barium titanate coated titanium scaffold improves osteogenesis and osseointegration with low-intensity pulsed ultrasound for large segmental bone defects

For large segmental bone defects,porous titanium scaffolds have some advantages,however,they lack electrical activity which hinders their further use.In this study,a barium titanate(BaTiO3)piezoelectric ceramic was used to modify the surface of a porous Ti6Al4V scaffold(pTi),which was characterized by scanning electron microscopy,energy dispersive spectroscopy,X-ray photoelectron spectroscopy,and roughness and water contact angle analyses.Low intensity pulsed ultrasound(LIPUS)was applied in vitro and in vivo study.The activity of bone marrow mesenchymal stem cells,including adhesion,proliferation,and gene expression,was significantly superior in the BaTiO3/pTi,pTi+LIPUS,and BaTiO3/pTi+LIPUS groups than in the pTi group.The activity was also higher in the BaTiO3/pTi+LIPUS group than in the BaTiO3/pTi and pTi+LIPUS groups.Additionally,micro-computed tomography,the mineral apposition rate,histomorphology,and the peak pull-out load showed that these scaffold conditions significantly enhanced osteogenesis and osseointegration 6 and 12 weeks after implantation in large segmental bone defects in the radius of rabbits compared with those resulting from the pTi condition.Consequently,the improved osteogenesis and osseointegration make the BaTiO3/pTi+LIPUS a promising method to promote bone regeneration in large segmental bone defects for clinical application.

Optimal regenerative repair of large segmental bone defect in a goat model with osteoinductive calcium phosphate bioceramic implants

So far,how to achieve the optimal regenerative repair of large load-bearing bone defects using artificial bone grafts is a huge challenge in clinic.In this study,a strategy of combining osteoinductive biphasic calcium phosphate(BCP)bioceramic scaffolds with intramedullary nail fixation for creating stable osteogenic microenvironment was applied to repair large segmental bone defects(3.0 cm in length)in goat femur model.The material characterization results showed that the BCP scaffold had the initial compressive strength of over 2.0 MPa,and total porosity of 84%.The cell culture experiments demonstrated that the scaffold had the excellent ability to promote the proliferation and osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells(BMSCs).The in vivo results showed that the intramedullary nail fixation maintained the initial stability and structural integrity of the implants at early stage,promoting the osteogenic process both guided and induced by the BCP scaffolds.At 9 months postoperatively,good integration between the implants and host bone was observed,and a large amount of newborn bones formed,accompanying with the degradation of the material.At 18 months postoperatively,almost the complete new bone substitution in the defect area was achieved.The maximum bending strength of the repaired bone defects reached to the 100% of normal femur at 18 months post-surgery.Our results demonstrated the good potential of osteoinductive BCP bioceramics in the regenerative repair of large load-bearing bone defects.The current study could provide an effective method to treat the clinical large segmental bone defects.