Identification of bone fracture in osseointegrated prostheses using Rayleigh wave methods

Osseointegration of a prosthesis offers a novel approach to enhancing the quality of life of an amputee because it makes an artificial limb an integral part of their body. While osseointegrated prostheses offer amputees many benefits, long-term health of the prosthesis fixture in the host bone is a concern. In particular, overloading of the fixture can result in damage to the host bone including bone fracture. This study offers a novel sensing strategy implemented on the percutaneous end of an osseointegrated prosthesis. Piezoelectric actuators are used to generate elastic stress waves in the prosthesis to interrogate the integrity of the prosthesis-bone interface. In this study, flexural mode Rayleigh waves are introduced in the prosthesis to identify the existence and location of fracture in the host bone. A prosthetic model consisting of a titanium rod implanted in a synthetic sawbone with piezoelectric wafer elements bonded to the rod surface is used to validate the proposed approach. The work reveals the waveforms associated with flexural wave modes are directly correlated to bone fracture occurring at the prosthesis-bone interface with fracture location identifiable in the reflect wave features.