Preliminary evaluation of different biomaterials for defect healing in an experimental osteoporotic rat model with dynamic PET-CT (dPET-CT) using F-18-sodium fluoride (NaF).

Abstract

The aim of the current study was to measure and compare the effect of calcium phosphate cement (CPC) and CPC enriched with strontium (SrCPC) for the healing of osteoporotic bone defects in the rat femur using (18)F-Sodium Fluoride dPET-CT. 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. 7 Rats have been treated either with CPC (Group 2) or with SrCPC (Group 3) for bone replacement and defect healing. Furthermore, a control group of 7 rats without any biomaterial (Group 1) was used for reference. 18 weeks after osteoporosis induction and 6 weeks following femoral surgery, dPET-CT studies scan were performed with (18)F-Sodium Fluoride. SUVs and a 2-tissue compartmental learning-machine model (K1-k4, VB, influx) were used for quantitative analysis. VB, reflecting the fractional blood volume and k3, reflecting the formation of fluoroapatite were the most sensitive parameters for the characterisation of healing process and revealed the best differentiation for the control group and the CPC group (Group 2) as well as for the CPC with strontium carbonate group (Group 3) (p<0.05). VB was decreased by the order of Group 1, Group 2 and Group 3, 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 these biomaterials. We found PET scanning using (18)F-Sodium Fluoride to be a sensitive and useful method for evaluation of bone healing after replacement with CPC or SrCPC.