Improvement of Porosity of a Calcium Phosphate Cement by Incorporation of Biodegradable Polymer Microspheres

In this study a biodegradable polymer microspheres were used to make an alpha-TCP calcium phosphate bone cement macroporous. The biodegradable polymer microspheres were synthesised at the laboratory and a sieve fraction of this microspheres ranging between 100 and 300 microns was incorporated in a calcium phosphate cement, where the powder contained a-Ca3(PO4)2 (a-TCP). The microspheres content of the cement was 10 %. The cement pastes were prepared at liquid-to-powder ratios from 0.32 to 0.40 ml/g. X-ray diffraction and Infra-red spectroscopy was performed to analyse the reaction on powdered samples that were let to set at different times in a Ringer’s solution at body temperature. Mercury porosimetry has been used at the main method for porosity measurements. Scanning electron microscopy (SEM) was performed on fractured samples fro microstructural analysis. The microspheres seemed to retard slightly the cement setting and to reduce progressively the compressive strength after aging in aqueous solutions which were continuously refreshed. SEM pictures and XRD patterns of the samples after 1 and 4 weeks of aging showed that the microspheres were dissolved progressively. Mercury porosimetry measurements assessed at different times of aging showed an improvement in the total porosity and the pore diameter of the set material and confirmed SEM and XRD results.