Numerical simulation of vibrational methods for the healing assessment of an internally fixated femur

Current bone healing monitoring techniques (X-ray, CT, manual manipulation) are subjective and qualitative. A quantitative monitoring technique for an internally fixated femur based on vibrational techniques is investigated. An intramedullary (IM) nail fixated femur will be at the focus of the investigation. The femur and fixation were modelled and their structural dynamics were solved using finite element analysis. This allowed visualisation of various mode shapes and identification of those most sensitive to healing. It was found that torsional modes were most sensitive to the stiffness change associated with healing. This data was then used as a guide for the placement of simulated accelerometer sensors and the simulated excitation point to predict the cross spectrum data that would be obtained during an experiment. Upon analysis of this data the torsional mode suggests that a relationship can be drawn between the natural frequency of the torsion mode and the state of health.