Non-Invasive Sensing of Active and Passive Joint Acoustic Emissions as a Biomarker of Periprosthetic Joint Effusions

OBJECTIVE: Total joint arthroplasty (TJA) effectively treats end-stage hip and knee joint diseases, improving patients' quality of life. However, 1-2% of TJA patients develop prosthetic joint infections (PJI), which are challenging to diagnose and treat. This study investigates non-invasive active vibration and passive acoustic emission analyses for PJI monitoring. METHODS: In this ex vivo study, periprosthetic joint effusions were simulated in seven cadaveric specimens with knee replacements by injecting saline and bacterial solutions into the joint space. Active sensing involved non-invasively stimulating the tibia with a miniature shaker, while passive sensing used manual stress to induce vibrations. Wideband, low-noise accelerometers captured the resulting vibrations, with spectral and temporal features extracted from the active and passive recordings, respectively. A qualitative analytical beam model of the knee-tibia system was developed to represent the fluid as structural changes at the boundary of the system. RESULTS: Both methods proved to be sensitive to the fluid in the joint space. Linear regression models were built using the most informative features, estimating fluid volume with Pearson's r of 0.79 and mean absolute errors of 11.1 mL (active) and 11.9 mL (passive). Trends in frequency and time signals were consistent between the experimental results and the analytical model. CONCLUSION: The results of this study demonstrated the utility of novel vibration-based techniques to monitor periprosthetic joint effusions. SIGNIFICANCE: These non-invasive techniques can lead to wearable devices for joint health monitoring, enabling PJI detection and personalized treatment plans, potentially improving patient outcomes and reducing PJI-related healthcare costs.