Large cortical bone pores in the tibia are associated with proximal femur strength

Abstract

Alterations of structure and density of cortical bone are associated with fragility fractures and can be assessed in vivo in humans at the tibia. Bone remodeling deficits in aging women have been recently linked to an increase in size of cortical pores. In this ex vivo study, we characterized the cortical microarchitecture of 19 tibiae from human donors (aged 69 to 94 years) to address, whether this can reflect impairments of the mechanical competence of the proximal femur, i.e., a major fracture site in osteoporosis. Scanning acoustic microscopy (12 μm pixel size) provided reference microstructural measurements at the left tibia, while the bone vBMD at this site was obtained using microcomputed tomography (microCT). The areal bone mineral density of both left and right femoral necks (aBMD neck ) was measured by dual‐energy X‐ray absorptiometry (DXA), while homogenized nonlinear finite element models based on high-resolution peripheral quantitative computed tomography provided hip stiffness and strength for one-legged standing and sideways falling loads. Hip strength was associated with aBMD neck (r = 0.74 to 0.78), with tibial cortical thickness (r = 0.81) and with measurements of the tibial cross-sectional geometry (r = 0.48 to 0.73) of the same leg. Tibial vBMD was associated with hip strength only for standing loads (r = 0.59 to 0.65). Cortical porosity (Ct.Po) of the tibia was not associated with any of the femoral parameters. However, the proportion of Ct.Po attributable to large pores (diameter > 100 μm) was associated with hip strength in both standing (r = -0.61) and falling (r = 0.48) conditions. When added to aBMD neck , the prevalence of large pores could explain up to 17% of the femur ultimate force. In conclusion, microstructural characteristics of the tibia reflect hip strength as well as femoral DXA, but it remains to be tested whether such properties can be measured in vivo.

Estimation of Cortical Bone Microstructure From Ultrasound Backscatter

“…Nineteen left tibia bones from human cadavers (6 male, 13 female, age: 83.7 ± 8.4 years, range: 69 -94 years) described in previous studies [1,15,35] were used for the ex-vivo measurements. Specimens were received without soft tissue and distal ends (cut off at approximately 50 %) and stored at −20 °C.…”

“…The samples were collected by the Institute of Anatomy, University of Lübeck in accordance with the German law "Gesetz über das Leichen-, Bestattungs-und Friedhofswesen des Landes Schleswig-Holstein -Abschnitt II, §9 (Leichenöffnung, anatomisch)" from 04.02.2005. Areal bone mineral density aBMD, macroscopic mechanical properties of the proximal femur of the same donors have been assessed in a previous study [1]. Briefly, aBMD was measured at the femur neck using a Hologic Discovery A scanner (Discovery QDR, Hologic Inc., USA).…”

“…HE mechanical integrity of cortical bone, which constitutes approximately 80% of the human skeleton mass, is a key factor of bone strength. A recent study suggested that reduced cortical thickness and the prevalence of large cortical pores in the tibia midshaft are biomarkers for reduced proximal femur strength [1]. Whereas cortical thickness can be measured reliably in-vivo at the central tibia shaft using second-generation high-resolution peripheral computed tomography (HRpQCT) [2] and various ultrasound technologies, including bi-directional axial transmission [3] and refraction-corrected ultrasound imaging [4], the estimation of pore micro-morphology is still challenging.…”

Patient-Specific Bone Multiscale Modelling, Fracture Simulation and Risk Analysis—A Survey

“…HR-pCT is a high-radiation CT restricted to the peripheral sites of the body, e.g., distal skeleton. HR-pCT provides in vivo imaging with spatial resolution smaller than 100 µm [75,81,153,154]. Similarities between the micro-geometry of peripheral bones and the micro-geometry of non-peripheral bones were discussed and considered by [154,155].…”

“…HR-pCT provides in vivo imaging with spatial resolution smaller than 100 µm [75,81,153,154]. Similarities between the micro-geometry of peripheral bones and the micro-geometry of non-peripheral bones were discussed and considered by [154,155]. Though HR-pCT is being increasingly used for in vivo bone research, its use has been limited to the distal radius and tibia [156].…”