Preparation and characterization of injectable PMMA-strontium-substituted bioactive glass bone cement composites

In most minimally-invasive procedures used to address severe pain arising from compression fractures of the vertebral bodies, such as percutaneous vertebroplasty (PVP), a poly(methyl methacrylate) (PMMA) bone cement is used. Shortcomings of this type of cement, such as high exotherm temperature and lack of bioactivity, are well known. We prepared different formulations of a composite bone cement, whose solid constituents consisted of PMMA beads and particles of a bioactive glass (BG), where 0-20%(w/w) of the calcium component was substituted by strontium. The difference between the formulations was in the relative amounts of the solid phase constituents and in the Sr-content of BG. We determined the influence of the mixture of solid phase constituents of the cement formulation on a collection of properties, such as maximum exotherm temperature (T_max ), setting time (t_set ), and injectability (I). The selection of the PMMA beads was crucial to obtain cement composite formulations capable to be efficiently injected. Results allowed to select nine solid phase mixtures to be further tested. Then, we determined the influence of the composition of these composite bone cements on T_max , t_set , I, and cell proliferation. The results showed that the performance of various of the selected composite cements was better than that of PMMA cement reference, with lower T_max , lower t_set , and higher I. We found that incorporation of Sr-substituted BGs into these materials bestows bioactivity properties associated with the role of Sr in bone formation, leading to some composite cement formulations that may be suitable for use in PVP. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1245-1257, 2018.