A piezoelectric bone fixation plate for in vivo application and monitoring of mechanical loading during fracture healing

Fracture non-union, the failure of a bone fracture to bridge, occurs in roughly 5%–10% of treated fractures and requires lengthy and expensive follow-up interventions. A significant body of research has investigated the efficacy of low-magnitude, high-frequency (LMHF) vibration as a treatment for femoral non-unions through the use of whole-body vibration. This work presents a novel piezoelectric fixation plate for investigating the efficacy of LMHF treatment by applying loads directly to the fracture site, thus reducing undesired systemic effects such as hormonal up-regulation induced by whole-body vibration. The fixation plate can apply mechanical loading in the LMHF regime and monitor the mechanical environment at the fracture site during ambulation to quantify progressive changes in callus stiffness over time as an indication of healing. Mechanical testing demonstrated the ability of the plate to provide displacements of up to 10 µm, as well as to estimate the changing stiffness of the fracture environment. (paper)