Research On An Injectable Calcium Sulfate Bone Cement Product

Calcium sulfate hemihydrate has been widely used as bone repair materials for years. Calcium sulfate-based bone cements have perfect biocompatibility, bioabsorbability, osteoinduction and osteoconduction. Its stable adsorption rate is good for fresh bone growth, which results in the great market prospect. Because of its biological properties and good physical characteristics, there are kinds of calcium sulfate-based bone cement products in the market. But none of them is created or invented in our country, and the products for clinical use in domestic market are highly expensive. In this research, we tried to explore a feasible production technology of a-calcium sulfate hemihydrate bone cements. And we hope to provide the technology and produce the product in the factory.The idea for our research was to systematically analyze a newly used clinical product in the market (MIIG115product from U.S.A.Wright company) at first. On basis of the product and its performance, we developed a self-characteristic and feasible preparation process to achieve the bone cement product.Firstly, the crystalline phase and micro-morphologies of MIIG115product powders were characterized with XRD, SEM, FT-IR and DSC. The product powders consisted of hexagonal short columnar a-calcium sulfate hemihydrate(a-CSH) particles which were about20-30μm long, about5-10μm in diameter. After our research, the results suggested that the re-crystallization hydrothermal method was a practical method for obtaining hexagonal short columnar a-calcium sulfate hemihydrate with uniform grain size distribution. The main influencing factors were the temperature for hydrothermal treatment and the content of crystal modifier. According to the laboratory results, we managed to realize the re-crystallization hydrothermal method technology for large-scale a-CSH particle production, forming the kilogram-class per cycle production capacity in the factory, and attaining the industrial production requirements from the factoryThen, the surface of a-CSH particles was treated with two ways, chemical modification and milling mix. The additives were stearic acid, carboxy methyl cellulose and hyaluronic acid. The roles of surface treatment ways and different additives were investigated by compression strength, setting time and practical injection results. The data suggested that the bone cement, consisted of a-CSH particle,1.5wt%stearic acid and0.15wt%-0.2wt%hyaluronic acid, had a good injection performance and certain compression strength, and its setting time was about8-10min. This technical solution demonstrates a feasible modification process route.Based on the preparation system of a-CSH particle, if certain hydroxyapatite was added, we predicted to get a new composite particle of hydroxyapatite wrapped a-CSH surface. The exploration of the composite particles would have a good guide for the research of a new product with controllable degradation property.