Potential of the scaling subtraction and the cross-correlation methods for osseointegration monitoring

The long-term perspective of this study is to implement in vivo some new noninvasive methods to monitor the bone prostheses sealing or osseointegration (dental implants, hip prostheses). Although the most widely used clinically, X-ray radiography suffers from low sensitivity, limiting for instance its ability to detect early loosening of a prosthesis. The potential of methods developed over the past twenty years and based on linear elasticity measurements has been shown in vitro, but their in vivo e ffectiveness is still questionable. The objective is to evaluate the potential of methods based on nonlinear elasticity measurement which showed greater sensitivity than the linear elastic response to the presence of weak contacts within a rigid structure, such as cracks. Two different methods called Scaling Subtraction Method and Cross-Correlation Method are compared in this study, using an experimental osseointegration mimicking model. One parameter extracted from the cross-correlation method is shown to be as sensitive as a linear clinical device subject to a thorough optimization. Further, this study shows that cross-correlation based methods are more sensitive than ones based on subtraction/addition, such like pulse inversion and derived methods.