Interfacial load monitoring and failure detection in total joint replacements via piezoresistive bone cement and electrical impedance tomography

Aseptic loosening, or loss of implant fixation, is a common complication following total joint replacement. Revision surgeries cost the healthcare system over $8 billion annually in the United States. Despite the prevalence of aseptic loosening, timely and accurate detection remains a challenge because traditional imaging modalities, such as plain radiographs, struggle to reliably detect the early stages of implant loosening. Motivated by this challenge, we present a novel approach forin vivomonitoring and failure detection of cemented joint replacements. Poly(methyl methacrylate) (PMMA) bone cement is modified with low volume fractions of chopped carbon fiber (CF) to impart piezoresistive-based self-sensing. Electrical impedance tomography (EIT) is then used to detect and monitor load-induced deformation and fracture of CF/PMMA in a phantom tank. We therefore show that EIT indeed is able to detect loading force on a prosthetic surrogate, distinguish between increasing load magnitudes, detect failure of implant fixation, and even distinguish between cement cracking and cement de-bonding without direct contact to the surrogate. Because EIT is a low-cost, physiologically benign, and potentially real-time imaging modality, the feasibility study herein presented could positively impact orthopedic researchers by providing, viain vivomonitoring, insight into the factors that initiate aseptic loosening.