Preliminary Development of an Opto-Electronic System for Ankle Instability Assessment

Ankle sprains are common sports injuries, with a substantial portion of patients developing Chronic Lateral Ankle Instability (CLAI) despite initial recovery. Traditional imaging methods such as stress radiographs, MRI and ultrasonography have limitations for accurately assessing ligament function. To achieve a more accurate assessment of ligament status, this study proposes a non-invasive method based on Near-Infrared Spectroscopy (NIRS) to objectively assess ankle ligament function. A multilayered tissue model centered on the Anterior Talofibular Ligament (ATFL) was developed. Monte-Carlo simulation was utilized to validate the photon propagation paths in NIRS reflection mode. Preliminary experiments were conducted using a fiber-optic spectroscopy system to measure the reflectance of the bilateral ankle ligaments on different subjects. The results showed that well-functioning ligaments had higher reflectance under edema-free conditions, while injured or poorly healing ligaments exhibited lower reflectance. These findings demonstrate the high sensitivity of the proposed NIRS-based technique, providing a foundation for developing wearable low power embedded diagnostic tools for clinical ligament assessment.