Vibration-Based Healing Assessment of an Internally Fixated Femur

The current techniques in assessing the healing of a fixated fractured long bone, which include X-ray, computed tomography (CT), and manual manipulation, are qualitative and its accuracy depends on the surgeon's experience. A lack of a robust and quantitative monitoring method of fractured bone healing limits the survival of orthopedic implants and the ability to accurately predict and prevent fixation failure and complications. This paper experimentally and computationally investigates the efficacy and the potential application of a vibration-based quantitative monitoring methodology. This nonintrusive technique incorporates the cross-spectra response of externally placed sensors located remotely from the fractured region. In this study, the test specimens are composite femurs fixated with an intramedullary nail fixation system and the epoxy adhesive applied in the osteotomized region is used to simulate the healing process. Epoxies with a 30-min and 2 h gel time are used separately to investigate the sensitivity of this healing assessment technique. The findings highlight the key vibrational modes to establish the state of healing and the quantification evaluation of healing of fixated femurs based on a formulated healing index is also presented. This efficacy study seeks to verify the viability of this external measurement technique for human health monitoring and the future development of healing devices.