| Total hip arthroplasty(THA)has become an important method for the treatment of various serious bone and joint diseases.However,modem artificial hip arthroplasty still has many problems which ultimately lead to the failure of surgery.Among them,the aseptic loosening after replacement of the prosthesis is most prominent.It is currently believed that wear of prosthesis and the failure of bone ingrowth are the main causes of aseptic loosening.Therefore,reducing the wear and strengthening the osseointegration ability of the prosthesis may improve the performance of the joint prosthesis and prolong the life of the prosthesis.In this study,a nanomultilayer films with alternating carbon layers and carbon-Ti composite layers,termed“a-C/a-C:Ti nanomultilayer films"(a-C NM films),were deposited on Ti6A14V using the magnetron sputtering.In vitro cytotoxicity test and in vivo implantation test in rabbits were carried out for the a-C NM films coated titanium alloy.THA surgeries were performed for twelve beagles using the coated Ti6A14V ball and cobalt chromium(CoCr)ball.The results showed that,compared with the untreated titanium alloy,the coated Ti6A14V had good in vivo and in vitro biocompatibility without obvious cytotoxicity.Two years after THA,polyethylene wear particles separated from periprosthetic tissue showed similar size,shape and number in both groups(all P>0.05).The surface roughness of the femoral head was slightly changed,but no significant difference between the groups(P=0.696).However,the systematic metal ion analysis showed the release of Co and Cr ions in the coated titanium alloy ball head group was significantly lower than that in the CoCr group(P<0.005).Histological analysis of the surrounding tissues of the prosthesis in CoCr group showed that the cellular response was more severe than that in the coated group(P=0.029).The head-taper interface showed slight galvanic corrosion in the CoCr group,but no corrosion was observed in the coated group.In this study,porous Ti6A14V were prepared by gel casting and two-step sintering technology.The implants could be fabricated with different porosities and pore sizes by controlling the sintering temperature and the quantity and size of spacer particles added to the Ti6A14V powder.The mechanical,biological and osteogenic properties of porous Ti6A14V prepared by new sintering process were studied in vitro and in vivo.Porous Ti6A14V with different porosity,and 3D printing were used for the comparisions.In addition,a full porous Ti6A14V acetabular cup was prepared.The finite element analysis and canine THA were carried out using the porous Ti6A14V acetabular cup with the traditional hydroxyapatite(HA)coated cup as the control.The results show that porous Ti6A14V has good mechanical properties,sufficient compressive strength and low modulus of elasticity,good biocompatibility and osteogenesis,which makes the porous Ti6A14V have good application prospects in biomedicine.Compared with 50%porosity,the porous Ti6A14V with 75%porosity has better mechanical properties,suitable pore size and porosity,and more bone ingrowth.Compared with 3D printing technology,the micro structure and mechanical properties of porous Ti6A14V prepared by sintering process are more similar to cancellous bone,without obvious stress shielding,and can achieve early stability more effectively after implantations.One year after canine THA,micro-CT and histopathological results showed that the bone grew inward in the porous group and the bone-implant contact rate was higher.Therefore,the porous Ti6A14V cup manufactured by new sintering technology can provide enough space and mechanical support without obvious stress shielding effect.Compared with the traditional HA coated cup,the porous cup can achieve in vivo stability more effectively.In summary,the a-C NM coated Ti6A14V has good biocompatibility and wear properties,thus it may be a good choice for the artificial femoral head;sintered porous Ti6A14V have good biocompatibility,mechanical properties and osteogenic ability,which is a good choice for acetabular prosthesis.Therefore,the applications of a-C NM coated Ti6A14V head and porous Ti6A14V cup may reduce the risk of aseptic loosening and prolong the life of prosthesis. |
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