Skip to: main navigation | content

SLAC National Accelerator Laboratory

Nanoscale Examination of Microdamage in Sheep Cortical Bone
April 2013 SSRL Science Summary by Lori Ann White, SLAC Office of Communications

Lead-uranyl acetate staining of damage morphologies in notched bone samples. (A, B) Staining of lacunae and canaliculi in the compressive region seen in 20 of the 23 samples; (C, D) Cross hatching damage around notch tip in the tensile region observed in 10 of 23 samples; (E, F) Crack propagating from notch tip in the tensile region in a single sample. Staining appears white due to high attenuation of lead-uranyl acetate, with bone tissue appearing grey and voids black. Scale bar: A,C,E = 50 μm; B,D,F = 5 μm. Sample created in the longitudinal plane of the bone.]

An important factor contributing to bone fractures is the accumulation of damaged tissue. Micro-damage can occur in bone tissue simply through the activities of daily life, which can reduce the tissue’s strength, stiffness and energy dissipation properties. In normal bone such damage is believed to stimulate bone remodeling and new bone formation. But diseases characterized by low bone mass such as osteoporosis alter bone remodeling and may weaken the tissue, leading to an increased risk of fracture. Current treatment costs for osteoporosis in the United States alone are in the tens of billions of dollars per year and are expected to grow.

A study recently published in PLoS ONE by researchers from Cornell University, Hospital for Special Surgery, New York, and SSRL describes nanoscale visualization of micro-damage in cortical bone tissue using x-ray negative staining and synchrotron-based x-ray imaging. The first study to examine bone damage at the nanoscale using full-field x-ray imaging in cortical bone, it provides new insights into bone damage and propagation of fractures. The method itself could have future applications for visualization of damage at the nanoscale, leading to greater knowledge of skeletal damage mechanisms.

In the study, beams created from sheep bones were damaged by applying either a monotonic or a fatigue load, then stained with x-ray negative stains of lead-uranyl acetate and sectioned to 50-micron thickness (much thicker than can be imaged with electron microscopy). The data were obtained using full-field transmission x-ray microscopy (TXM) at SSRL Beam Line 6-2, creating nanoscale images of micro-damage throughout this thickness with 30-nm resolution. Images revealed increased staining (pointing to damage), cross hatching and micro-cracks in the fatigue-loaded bone samples (Figure 1). In both cases staining was localized to existing bone structures, with limited new surfaces created. The images were compared with lower-resolution images obtained using micro-computed tomography (microCT), a standard technique for imaging micro-damage in bone; the structures revealed by the TXM images were not discernible in the microCT images and the damage manifested diffusely, appearing larger than in the TXM images. MicroCT analyses of micro-damage may, therefore, overestimate the damage present. Thus nanoscale TXM imaging through these relatively thick specimens can provide crucial details needed to discern features relevant to bone disease.


Primary Citation

G. R. Brock, G. Kim, A. R. Ingraffea, J. C. Andrews, P. Pianetta, M. C. H. van der Meulen, "Nanoscale Examination of Microdamage in Sheep Cortical Bone Using Synchrotron Radiation Transmission X-ray Microscopy", PLoS ONE 8, e57942 (2013)

Related Links


Garry R. Brock, Cornell University
Joy C. Andrews, Stanford Synchrotron Radiation Lightsource
Marjolein C. H. van der Meulen, Cornell University

2575 Sand Hill Road, MS: 99, Menlo Park, California, 94025, USA Tel: 650-926-4000 | Fax: 650-926-4100