High-Tech Hip Implant for Wireless Temperature Measurements In Vivo

Abstract

When walking long distances, hip prostheses heat up due to friction. The influence of articulating materials and lubricating properties of synovia on the final temperatures, as well as any potential biological consequences, are unknown. Such knowledge is essential for optimizing implant materials, identifying patients who are possibly at risk of implant loosening, and proving the concepts of current joint simulators. An instrumented hip implant with telemetric data transfer was developed to measure the implant temperatures in vivo. A clinical study with 100 patients is planned to measure the implant temperatures for different combinations of head and cup materials during walking. This study will answer the question of whether patients with synovia with poor lubricating properties may be at risk for thermally induced bone necrosis and subsequent implant failure. The study will also deliver the different friction properties of various implant materials and prove the significance of wear simulator tests. A clinically successful titanium hip endoprosthesis was modified to house the electronics inside its hollow neck. The electronics are powered by an external induction coil fixed around the joint. A temperature sensor inside the implant triggers a timer circuit, which produces an inductive pulse train with temperature-dependent intervals. This signal is detected by a giant magnetoresistive sensor fixed near the external energy coil. The implant temperature is measured with an accuracy of 0.1°C in a range between 20°C and 58°C and at a sampling rate of 2–10 Hz. This rate could be considerably increased for measuring other data, such as implant strain or vibration. The employed technique of transmitting data from inside of a closed titanium implant by low frequency magnetic pulses eliminates the need to use an electrical feedthrough and an antenna outside of the implant. It enables the design of mechanically safe and simple instrumented implants.

Design and Evaluation of an Inductive Powering Unit for Implantable Medical Devices Using Gpu Computing

“…. 20 elements with a turns discretization (i.e., values of a K and N ) of the order 2 10 . Thus, performance evaluation of a single design version with three uncontrolled geometric parameters (distance, shift, inclination) can take about 1 .…”

“…. 10 in comparison with parallel computing on the host CPU with the turns discretization of the order 2 10 .…”

Implantable Devices: Issues and Challenges

“…The temperature telemetry with thermistor, electronic circuit and power/data coil are placed inside the neck of the implant [31]. (B) Retinal prosthesis: (a) the schematic version of a minimally invasive approach; (b) photograph of an implant in the eye of a minipig [32,33].…”

A Review of the Neural and Behavioral Consequences for Unitizing Emotional and Neutral Information

“…Although the effects of arousal on associative binding initially seemed inconsistent – with arousal sometimes enhancing the binding of details (e.g., MacKay et al, 2004) and at other times having no effect, or impairing, such binding (e.g., Kensinger and Schacter, 2006; Bergmann et al, 2012; note that the latter examines interactions between both valence and arousal) – more recent accounts have proposed a unified framework for understanding the complex pattern. Mather (2007) proposed an “object-based” framework, with arousal enhancing the binding of information encoded as an item feature but not of information encoded as a contextual detail (see also Kensinger, 2007, 2009).…”