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

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 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 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 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, via in vivo monitoring, insight into the factors that initiate aseptic loosening.

Simple Smart Implants: Simultaneous Monitoring of Loosening and Temperature in Orthopaedics With an Embedded Ultrasound Transducer

“…Nuclear imaging has long been advocated as an alternative to plain radiographs to diagnose loosening, but small study sizes mean current available evidence is still at high risk of bias [14]. A more recently explored imaging modality, electrical impedance tomography, used piezoresistive bone cement to detect loosening of a hip replacement in an experimental setup that simulated fluid ingress [24], [25]. With our proposed concept measuring local implant fixation, direct performance comparisons cannot yet be drawn to these imaging modalities without in vivo testing of either concept.…”

“…Recent research, however, has demonstrated that accurate measurements can be obtained when using external circuitry to interrogate simpler passive modifications. Electrical impedance tomography of piezoresistive cement has been proposed to detect loosening [24], [25], whilst a thermistorcontaining LCR circuit has been proposed to measure temperature as a proxy for infection [26].…”

Quantitative Evaluations with 2d Electrical Resistance Tomography in the Low-Conductivity Solutions Using 3d-Printed Phantoms and Sucrose Crystal Agglomerate Assessments

“…These applications involve different spatial sizes of the target region of interest and varied conductivity profiles. Even though it is challenging to do ERT imaging in low-conductivity environments [ 22 ], many applications have been demonstrated, such as imaging composite structures [ 23 ] and bone cement [ 24 ].…”

Process Monitoring of Antisolvent Based Crystallization in Low Conductivity Solutions Using Electrical Impedance Spectroscopy and 2-D Electrical Resistance Tomography

“…Given the low conductivity of the sucrose solutions in the range of a few µS/cm [33], electrical resistance tomography (ERT) reconstructions become challenging due to the small changes in the resistances [34]. However, in the recent years, it has been demonstrated that the ERT can be successfully implemented with materials with low conductivity such as composite structures [35], graphene-based nano-composite films [36] and bone cement [37]. Herein, electrical properties of antisolvent crystallization in the ternary-sucrose-ethanol-water system were analysed by utilizing 1-D thin electrode impedance spectroscopy.…”