PREOPERATIVE ADDITION OF CALCIUM-IONS OR CALCIUM-PHOSPHATE CRYSTALS TO PEO/PBT COPOLYMERS (POLYACTIVE(TM)) STIMULATES BONE MINERALIZATION IN-VITRO

The effect of the pre-operative addition of calcium ions or calcium phosphate to bioactive PEO/PBT copolymers (Polyactive(TM)) on bone-bonding characteristics was evaluated in vitro. Atomic absorption spectroscopy was used to determine variations in the calcium concentration in the culture medium due to calcium release from the pretreated copolymers. Bone marrow cells were cultured on the copolymers for 2 and 3 weeks. Differences in formation rate and mineralization of bone nodules were analysed using LM and TEM techniques. Formation of bone nodules was observed after 2 weeks on non-treated copolymers. However,no mineralization in these bone nodules could be detected during the 3 weeks of this experiment. Addition of calcium ions to the copolymers initially increased the calcium concentration of the culture medium and led to formation of mineralized nodules after 2 weeks. The two precalcified copolymers had different effects on the calcium concentration of the culture medium. Instead of nodules, two or three continuous cell layers were formed and mineralization was observed after 2 weeks. Longer culture periods resulted in more mineralization in close contact with the copolymer surface. Based on the results of this experiment we conclude that the pre-operative addition of calcium ions or calcium phosphate to PEO/PBT copolymers stimulates mineralization in bone marrow cell cultures, which is an indication for better bone-bonding characteristics in vitro