Abstract
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Objectives The aim of the current study was to measure and compare the effect of different biomaterials for the healing of osteoporotic bone defects in the rat femur using 18F-Fluoride dPET-CT.
Methods Osteoporosis was induced by ovariectomy and a calcium restricted diet. After three months, rats were operated to create a 4 mm defect in the distal metaphyseal femur with internal fixation. The biomaterials comprise calcium phosphate (CPC), CPC with strontium carbonate (CPCSr20), porous silicate protocol (Sc-B30), Sc-B30Sr20, B30, plain iron foam, iron foam with Sr20, and iron foam with bisphosphonate. Eight groups were created according to the biomaterials with 8 rats per group. Furthermore, a control group of 8 rats without biomaterial (Group 1) was used as reference. 18 weeks after osteoporosis induction and 6 weeks following femoral surgery, dPET-CT studies scan were performed with F-18-Fluoride. SUVs and a 2-tissue compartmental learning-machine model (K1-k4, VB, influx) were used for quantitative analysis.
Results VB and k3 were the most sensitive parameters in the defect and revealed the best differentiation for the control group and the CPC group (Group 2) as well as the CPC with strontium carbonate group (Group 3) (Wilcoxon rank-sum test, p<0.05). VB was decreased by the order of Group1, Group 2 and Group3, while k3 was increased by the same order. Therefore, the data direct to a decreased fractional blood volume and increased fixation of fluoride in rats with biomaterials like CPC and CPC with strontium carbonate.
Conclusions Fixation of fluoride in the bone matrix can be enhanced using CPC or CPC with strontium carbonate as biomaterials in osteoporotic bone.