Optimization of the formulation and mechanical properties of starch based partially degradable bone cements.

Previous studies have shown the possibility of developing in-situ polymerizable hydrogels that disclose a range of properties that might allow for their use as bone cements. Their main advantage is to be partially degradable, which is important to allow bone ingrowth (better fixation). In addition, their uptake of water makes them less agressive for the tissues, disclosing better fatigue properties and ideal for release of drugs when in service. This work reports a statistical study of the formulation of partially degradable acrylic bone cements that include on their composition corn starch/cellulose acetate blends (SCA). The aim was to optimize a set of properties (mechanical, swelling/degradation and curing) by changing the values of some parameters such as SCA amount and particle size and molar ratio of the acrylic monomers. Statistical tests demonstrated that the most important parameter was the molar ratio of monomers, with the SCA percentage also playing a role. It was possible to develop formulations with mechanical properties in the range of ASTM specifications and with polymerization temperatures lower than those of commercial acrylic cements. Some formulations were subsequently selected for tensile and dynamic mechanical thermal analysis (DMA) tests, under dry and wet conditions.