Cortical Bone in the Human Femoral Neck: Three-Dimensional Appearance and Porosity Using Synchrotron Radiation

Abstract

A high-resolution CT system using synchrotron radiation allowed visualization of the 3D cortical bone microarchitecture and measurement of intracortical porosity of femoral neck cortical bone specimens from 19 female cadavers imaged at 10.13-m resolution. 3D reconstruction of specimens showed osteonal system arrangement. Mean porosity was 15.88%. This technique will provide insights into the mechanisms involved in osteoporotic hip fractures.Introduction: The purpose of this study was to show that a high-resolution CT system using synchrotron radiation (SR) allows visualization of the 3D cortical bone microarchitecture of the human femoral neck and quantification of intracortical porosity. Materials and Methods: Bone specimens from the inferior femoral neck were obtained from 19 female cadavers with no hip fracture (mean, 86.9 Ϯ 8.3 years). The specimens, consisting of embedded ϳ7 ϫ 7 ϫ 12-mm cortical bone parallelepipeds, were imaged using SR at 10.13-m resolution. Commercial software was used to visualize both the 660 ϫ 660 ϫ 660-voxel volumes and the 2D axial slices through each volume. Qualitative examination of 2D axial slices focused on the appearance of the vessel canal system, presence of small bright zones (fully mineralized tissue) in the osseous matrix, and presence of cracks. A method was developed to automatically measure 3D intracortical porosity after separating pure bone from pores and cortical bone from trabecular bone. Results and Conclusions: 3D reconstruction of the specimens showed the entire structure and arrangement of the osteonal systems, parallel to the axis of the femoral neck. Bright zones were seen in the outer cortex. No cracks were observed. Porosity values varied widely from 4.96% to 38.87% (mean, 15.88 Ϯ 9.87%). This study establishes that SR microtomography can be used to display the 3D bone microstructure of the human femoral neck cortex and to quantify intracortical porosity. This technique will provide insights into the mechanisms involved in cortical bone loss and osteoporotic hip fractures.

Young-elderly differences in bone density, geometry and strength indices depend on proximal femur sub-region: A cross sectional study in Caucasian-American women

“…The higher value of cBMD at the FN in the elderly women, compared to the TR (which decreased with age), may be due to the presence of highly mineralized areas in the FN cortex of elderly women. These results are consistent with findings reporting increased mineralized tissue, areas of higher mineral content than the adjacent cortex, at the FN in elderly populations [4,5,37]. The origin of these highly mineralized areas may be due to subperiosteal calcification derived from the periosteum [11], necrotic tissue where minerals continue to accumulate [5] or calcified fibrocartilagenous tissue at points of attachments of tendons or capsules [5,37].…”

Bone three-dimensional microstructural features of the common osteoporotic fracture sites

“…Cortical thickness (Ct. Th) declines by 3% to 5% and Ct.Po increases by 31% to 33% per decade between ages of 60 to 90 years [49] . The number of cortical pores has no marked age-related changes, whereas the diameter of cortical pore increases significantly with age [49,[55][56][57] . Accordingly, increase of cortical porosity with advancing age is predominantly attributable to enlarged cortical pores.…”

Quantitative ultrasound of cortical bone in the femoral neck predicts femur strength: Results of a pilot study

“…Bousson and colleagues (40) found porosity values in the inferior cortex varying from 4.96% to 38.87% (mean, 15.88% AE 9.87%). Several studies pointed that the cortical bone properties in the neck, and in particular in the anterior and inferior regions, were different in fracture cases and postmortem controls.…”