Bulk properties and bioactivity assessment of porous polymethylmethacrylate cement loaded with calcium phosphates under simulated physiological conditions

Abstract

Polymethylmethacrylate (PMMA) cements are widely used in spinal surgery. Nevertheless, these types of cements present some documented drawbacks. Therefore, efforts have been made to improve the properties and biological performance of solid PMMA. A porous structure would seem to be advantageous for anchoring purposes. This work studied the bulk physicochemical, mechanical and interconnectivity properties of porous PMMA cements loaded with various amounts of calcium phosphate (CaP). As a measure of bioactivity, changes of PMMA cements under simulated physiological conditions were studied in a calcium phosphate solution for 0, 3, 7, 14, 21 and 28days. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), micro-computed tomography (μ-CT) and mechanical compression tests were performed to characterize the morphology, crystallographic and chemical composition, interconnectivity and mechanical properties, respectively. SEM allowed observing the result of loading CaP into the porous PMMA, which was corroborated by XRD, FTIR and μ-CT. No interference of the CaP with the PMMA was detected. μ-CT described similar interconnectivity and pore distribution for all CaP percentages. Mechanical properties were not significantly altered by the CaP percentages or the immersion time. Hence, porous PMMA was effectively loaded with CaP, which provided the material with properties for potential osteoconductivity.