Inertial Tracking System for Monitoring Dual Mobility Hip Implants In Vitro

Abstract

Dual mobility (DM) implants are being increasingly used for total hip arthroplasties due to the additional range of motion and joint stability they afford over more traditional implant types. Currently, there are no reported methods for monitoring their motions under realistic operating conditions while in vitro and, therefore, it is challenging to predict how they will function under clinically relevant conditions and what failure modes may exist. This study reports the development, calibration, and validation of a novel inertial tracking system that directly mounts to the mobile liner of DM implants. The tracker was custom built and based on a miniaturized, off-the-shelf inertial measurement unit (IMU) and employed a gradient-decent sensor fusion algorithm for amalgamating nine degree-of-freedom IMU readings into three-axis orientation estimates. Additionally, a novel approach to magnetic interference mitigation using a fixed solenoid and magnetic field simulation was evaluated. The system produced orientation measurements to within 1.0° of the true value under ideal conditions and 3.9° with a negligible drift while in vitro, submerged in lubricant, and without a line of sight.

Inertial Sensors for Hip Arthroplasty Rehabilitation: A Scoping Review

“…Research [19] addresses the follow-up of dual-motion hip implants, while [30] argues that a hip replacement affects body movements; [34] focuses on open-source surgical navigation using optical tracking; [35,37] presents improved results of hip arthroplasty using the inertial measurement unit (IMU); and [36] uses Smart Trail to estimate hip movement.…”

“…Ref. [19] focuses on the inertial tracking of dual-motion hip implants; [30] discusses wearable sensors for monitoring lower body movements. On the other hand, [34] offers an affordable PAO navigation solution, [35] discusses the use of the Kalman filter to improve the accuracy of the sensor, and finally, [36] proposes the Smart Trail system to predict movements from the hip.…”

“…Ref. [19] focuses on inertial sensors to monitor hip arthroplasty, while [30,[34][35][36] focus on reach, mobility, sensors, improvement of precision, safety, quantitative results, and rehabilitation.…”

“…Refs. [19,[24][25][26][30][31][32][33][34][35][36][37] have shown that IMUs for hip arthroplasty offer precision, safety, low cost, and relatively low complexity. 4.2.6.…”

“…Refs. [19,20,[24][25][26][27][28][30][31][32][33][34][35][36][37] have revealed limitations in inertial sensors used in hip arthroplasty, such as noise, interference, inaccurate joint angle measurement, problems with training data, lack of sensitivity, and temperature variation in small samples.…”