Vertebral Body Compressive Strength Evaluated by Dual-Energy X-Ray Absorptiometry and Hounsfield Units In Vitro

Dual-energy X-ray absorptiometry (DXA) and Hounsfield unit (HU) are 2 technologies used in vivo to assess bone mineral density and to predict fracture risk. However, few in vitro studies focus on the difference between the 2 technologies in the ability to determine vertebral body compressive strength. Forty-two lumbar vertebrates were harvested from 7 mature goats. All the vertebrae were imaged using clinical computed tomography and assessed by DXA subsequently. The individual vertebral body was then mechanically tested to failure in compression, to determine ultimate load and stress. HU has a moderate correlation with DXA (r = 0.64). DXA has significant associations with ultimate load and stress (r = 0.59 and 0.69, respectively). Significant positive linear correlations were also found between HU and ultimate load (r = 0.65) and stress (r = 0.81). There was no significant difference between HU and DXA to predict the ultimate load (t = 0.56, p = 0.577) or the ultimate stress (t = 1.62, p = 0.112). HU has an equal predictive value as the DXA for whole vertebral body compressive strength. This work supports the application of the HU measurement using clinical computed tomography imaging technology to assess bone strength and fracture risk.