Bending stiffness of healing fractures can be calculated from quantitative computed tomography

This paper revisits the relationship between bone densitometry and fracture healing by using quantitative computed tomography (QCT) to assess bone density. In recent time the correlation between bone mineral density (BMD) and mechanical stability of healing bone has been investigated with the purpose to predict mechanical properties of healing fractures--such as their loading capability--from data which can be collected non-invasive. One goal is to obtain a functional dependency between data obtained from QCT and the mechanical properties. In this study the computation of the mechanical stability of fractures from data obtained by QCT is proved to be reliable (r2 = 0.947 and P < 0.0001). As one result most dependencies between mechanical data and stiffness are not linear but quadratic (r2 > 0.72, P < 0.0005). The only linear dependencies are found between the second polar moment of inertia (Ip), calculated from geometric midpoint and center of mass (r2 = 0.688, P = 0.0052 and r2 = 0.677, P = 0.0010), and the average density (r2 = 0.836, P < 0.0001) versus bending stiffness. A functional dependency between bending stiffness and bone mineral content (BMC) of the fracture area in the fracture gap can be provided. The data presented in this work has been computed by a new algorithm developed by the author for detecting the fracture area of minimal density automatically in three-dimensional data obtained from QCT.