Fractal analysis of radiographic trabecular bone texture and bone mineral density: Two complementary parameters related to osteoporotic fractures

Trabecular bone microarchitecture and bone mineral density (BMD) are two ma in factors related to osteoporotic fractures. Currently, however, microarch itecture is not evaluated. We have developed and validated a trabecular bon e texture analysis from radiographic images. The objective was to determine if the fractal analysis of texture was able to distinguish osteoporotic fr acture groups from control groups, either in vertebrae, hip, or wrist fract ures, and to determine if this indicator and BMD were independent and compl ementary, In this cross-sectional unicenter case-control population study i n postmenopausal women, 107 fracture cases were enrolled and age-matched wi th 197 control cases. This population comprised 40 vertebral fractures (wit h 70 controls), 30 hip fractures (55 controls), and 37 wrist fractures (62 controls). Hip and lumbar spine BMD were measured by double-energy X-ray ab sorptiometry. Fractal analysis of texture was performed on calcaneus radiog raphs and the result was expressed as the H parameter (H = 2-fractal dimens ion), The H parameter showed a lower value (0.679 +/- 0.053 SD) in fracture cases versus control cases (0.696 +/- 0.030; p = 0.007), the statistical s ignificance persisting after adjustment for age and for lumbar spine (LS) o r hip BMD, This result was confirmed in vertebral fractures (p = 0.0001) an d hip fractures (p = 0.003) but not wrist fractures (p = 0.07), We determin ed the threshold between high and low H values and then the odds ratios (OR ) of fracture for low H for BMD less than or equal to -2.5 SD in T score an d for the combinations of both parameters, The OR of fracture for low H was 1.6 (95% CI, 1.1-2.6). For LS BMD less than or equal to -2.5 SD the OR of 6.1 (3.4-10.8) shifted to 9.0 (4.0-20.4) when we added low H and for hip BM D it shifted from 5.6 (3.3-9.4) to 8.1 (4.0-16.8), In vertebral, hip, and w rist fracture cases the results were also significant. These data have show n that the fractal analysis of texture on calcaneus radiographs can disting uish osteoporotic fracture groups from control groups. This analysis and BM D provide independent and complementary information. These data suggest tha t we can improve the fracture risk evaluation by adding information related to microarchitecture, derived from analysis of conventional radiographic i mages.