Investigation of a Passive Sensor Array for Diagnosis of Loosening of Endoprosthetic Implants

Abstract

Currently, imaging methods are used to diagnose loosening of endoprosthetic implants, but fail to achieve 100% accuracy. In this study, a passive sensor array which is based on the interaction between magnetic oscillators inside the implant and an excitation coil outside the patient was investigated. The excited oscillators produce sound in the audible range, which varies according to the extent of loosening. By performing several experimental tests, the sensor array was optimized to guarantee reproducible and selective excitation of the sound emission. Variation in the distance between the oscillators demonstrated a definite influence on the quality of the generated sound signal. Furthermore, a numerical design analysis using the boundary element method was generated for consideration of the magnetic field and the selectivity of the oscillators during excitation. The numerical simulation of the coil showed the higher selectivity of a coil with a C-shape compared to a cylindrical coil. Based on these investigations, the passive sensor system reveals the potential for detection of implant loosening. Future aims include the further miniaturization of the oscillators and measurements to determine the sensitivity of the proposed sensor system.

Development of a non-invasive diagnostic technique for acetabular component loosening in total hip replacements

“…Most THR stability assessment studies have focused on the femoral component [20][21][22][23][24][35][36][37][38][39][40][41][42]. Vibration analysis studies on acetabular loosening are limited because the acetabulum has a complex geometry compared to the femur and has a thicker overlaying soft tissue layer, which acts as a signal buffer.…”

“…The majority of previous studies on vibration analysis [20][21][22][23][24][35][36][37][38][39][40][41][42] assessed loosening of the femoral stem. Since a high rate of loosening in the acetabular component has been reported in the clinically [43]; therefore, the aim of the present study was to compare ultrasound and accelerometer methods and to examine the viability of the vibration analysis technique to accurately detect acetabular component loosening.…”

“…Georgiou and Cunningham [23] also compared vibration analysis with standard radiological assessment and demonstrated that vibration analysis improved diagnostic precision by 20%; moreover, they were able to detect 13% more cases than radiological diagnosis with 81% sensitivity and 89% specificity. Other research groups have used vibration analysis for different orthopaedic applications such as; the telemetry technique to assess THR femoral loosening [24][25][26], trans-femoral osseointegration [27][28][29], intra-operative initial implant stability [6,[30][31][32][33], THR femoral stability utilising acoustic resonance responses [7,[34][35][36][37][38][39][40][41], and complete THR component loosening (femoral and acetabular) [5].…”

Internet of Things and data mining: From applications to techniques and systems

“…Bringing monitoring to a patient rather than vice-versa provides a multitude of benefits. Without constant monitoring, particularly during stages of rehabilitation and recovery (Hii et al, 2011), patient relapse is shown to be far more common (Fong & Chung, 2013). Pressures on important medical resources in both equipment and medical professionals are reduced and significantly increased access to care means patients are given the freedom of being able to live much more independently, greatly improving their quality of life (Niewolny, 2013).…”

In vivo monitoring of implant osseointegration in a rabbit model using acoustic sound analysis

“…14,15 For application in orthopedic and trauma surgery, a contact-free monitoring device is necessary. For this reason, a novel technology based on the principle of acoustic sound analysis was developed, allowing non-invasive acoustic excitation, [16][17][18] using a New Zealand White Rabbit (NZWR) model. The NZWR is a reasonable, cost-effective alternative to larger mammals.…”