Fracture characterization in cancellous bone specimens via surface difference evaluation of 3D registered pre- and post-compression micro-CT scans

Abstract

In recent years, increasingly stringent passenger vehicle safety requirements have led to a renewed interest in the fracture properties of bone. It has been shown that can- cellous bone architecture is strongly linked to its overall behavior (Follet et al. 2011; Prot et al. 2015). Micro- fracture mechanisms have been resolved by time- consuming direct microscopy (Prot et al. 2012) or by the use of calcein (Lambers et al. 2014; Hernandez et al. 2014). Furthermore, the application of CT scanners, along with the development of registration algorithms, has allowed separated portions of fractured specimen to be registered to the pre-compression scan so as to quantify the differ- ence between 3D shapes as a mean to characterize the fracture behavior (Tassani & Matsopoulos 2014). How- ever, this method is operator-dependent in the case of multiple fracture zone identification and requires suffi- cient deformation of the specimen to obtain distinct reg- istration sets. In addition, built-in micro-compression testers, developed by CT scanner manufacturers, are limited to loading at low levels of strain rate, which does not allow measurement over a range that is representative of daily life. The goal of this study was to identify distinct fracture patterns based on micro-CT scans of cancellous bone specimens, loaded over a large range of strain rates, without the need for specimens that have broken into separate pieces.