MICROSTRUCTURAL DIFFERENCES BETWEEN OSTEOPOROTIC AND OSTEOARTHRITIC FEMORAL CANCELLOUS BONE: AN IN VITRO MAGNETIC RESONANCE INVESTIGATION AT 9.4 T

Objective: The main purpose of this study is to investigate microstructural differences in cancellous bone of arthritic and osteoporotic patients using extracted samples of femoral heads analyzed with a magnetic resonance (MR) high resolution scanner at 9.4 T. In a first step an examination on bone tissue specimens, taken from patients underwent primary total hip arthroplasty (THA) for hip fracture or for hip osteoarthritis was performed. The chosen NMR parameter to perform this study was the T2 relaxation time. Material and Methods: Samples of cancellous bone taken from 10 osteoporotic women with a femoral fracture and from 10 age matched arthritic women with THA were analysed. The local Ethics Committee approved the investigation and every patient signed an informed consent. Each bone sample was immersed in 4 % paraformaldeyde and PBS. The imaging protocol was comprised of twelve slices, with slice thickness of 1 mm for each specimen and in plane resolution of 60 microns. A Spin-echo sequence was used with 32 Echo Times (TE) from 3-100 ms. We calculated T2 mean values and standard deviation (SD) in subchondral and metaphysis sections. P values<0.05 were considered statistically significant. Results: No significant difference was found between T2 values measured in subchondral and metaphysis section (T2=66.81 ms in subchondral, T2=68.48 ms in metaphysis section) in osteoporotic patients. Significant difference was found between T2 values measured in subchondral and metaphysis section (T2=43.37 ms in subchondral, T2=50.48 ms in metaphysis section) in osteoarthritic patients. T2 values are related to trabecular bone density (TBD) in cancellous bone. As a consequence this data shows a different TBD in cancellous bone specimens of osteoarthritic patients only, which is higher in subchondral compared to metaphysis section. Conclusion: T2 investigation of cancellous bone specimens shows potential to detect differences in microstructural trabecular bone rearrangement of arthritic and osteoporotic bone.