Calcium sulfate and phosphate have a long clinical history of use as bone-void fillers (BVF) with established biocompatibility and resorption profiles. It has been widely reported that the addition of ‘impurity’ elements such as Silicon, Strontium and Zinc to calcium phosphate is advantageous, resulting in an improved bone healing response. This study examined the in vivo response of two formulations of calcium sulfate, as 3mm diameter hemispherical beads, in critical sized defects created in cancellous bone of distal femur and proximal tibia (10mm diameter × 13mm depth) in adult sheep; beads prepared from recrystallised pharmaceutical grade calcium sulfate (RPCS, Stimulan, Biocomposites Ltd, UK) and a lower purity medical grade material containing 1% strontium (SrCS). The animals were sacrificed at 3, 6 and 12 weeks post implantation and the surgical sites analysed using microCT and decalcified histology.Background
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