Silicate bioceramic/PMMA composite bone cement with distinctive physicochemical and bioactive properties

Polymethyl methacrylate (PMMA) bone cement has been widely used for orthopedic application due to its high mechanical strength and proper setting time. However, the major shortcomings of PMMA bone cement are its relatively low osseointegration and strong exothermic reactions. Silicate-based bioceramics, like akermanite (Ca2MgSi2O7, AKT), have been demonstrated to possess excellent osteostimulation ability and controlled biodegradability. The purpose of this study is to harness the advantages of both PMMA and AKT in order to prepare a new kind of composite bone cement (AKT/PMMA) with superior mechanical strength, improved exothermic effect and osteogenic activity. AKT particles were uniformly incorporated into the matrix of PMMA cement. The effect of AKT on the in vitro setting behaviors, and mechanical and biological properties of resultant composite cements was systematically investigated. The results showed that the prepared AKT/PMMA composite bone cements revealed significantly decreased polymerization temperature as compared with pure PMMA, but maintained ideal setting times (12-14 min) and high mechanical strength (similar to 100 MPa for compressive strength). Most interestingly, the incorporation of AKT into PMMA improved its osteogenic activity, as indicated by the significantly enhanced apatite-mineralization ability and stimulatory effect on the proliferation and alkaline phosphate (ALP) activity of osteoblasts. The results suggest that AKT/PMMA composite bone cements possess distinctive physicochemical and bioactive properties, and are a promising injectable biomaterial for orthopedic applications.