Interfacial Load Monitoring and Failure Detection in Total Joint Replacements via Piezoresistive Bone Cement and Electrical Impedance Tomography

TL;DR

This paper introduces a novel in vivo monitoring method for joint replacements using piezoresistive bone cement and electrical impedance tomography, enabling early failure detection and improving post-operative care.

Contribution

It presents a new approach combining piezoresistive bone cement and EIT for real-time load monitoring and failure detection in joint replacements, addressing limitations of traditional imaging.

Findings

EIT can detect load-induced deformation and fracture in cement

The method distinguishes between cement cracking and de-bonding

Potential for real-time, low-cost implant monitoring

Abstract

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 US. 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 for in vivo monitoring 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 adeptly 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. Because EIT is a low-cost, physiologically benign, and potentially real-time imaging modality, the feasibility study herein presented has potential to transform the standard of care for post-operative monitoring of implant conditions. Beyond clinical relevance, this technique could positively impact orthopedic researchers by providing, via in vivo monitoring, insight into the factors that initiate aseptic loosening.