Fiber Bragg Grating Sensors for Clinical Measurement of the First Metatarsophalangeal Joint Quasi-Stiffness

Abstract

Assessing the mobility of the first metatarsophalangeal joint (MTPJ) of a human foot is useful in clinical practice but there are no standard methods of measurement. The present study developed a new instrumentation using Fiber Bragg grating (FBG) sensor and load cell to quantify the first MTPJ quasi-stiffness in a clinical setting. This system is portable, lightweight, and allows quantification of quasi-stiffness over different ranges of motion in both loading and unloading directions. The laboratory setting validation results showed that FBG sensors could measure MTPJ angular displacement with reasonably good accuracy. The proposed system was successfully trialed in a hospital setting operated by a clinician on eight human subjects. Non-linear torque-angular displacement relationship was observed in both loading and unloading phases, with varying MTPJ quasi-stiffness in the early [loading 6.30 (2.62) Nmm/ o unloading 8.46 (2.29) Nmm/ o ], middle [loading 7.13 (2.17) Nmm/ o , unloading 11.11 (2.94) Nmm/ o ], and late [loading 24.54 (7.14) Nmm/ o , unloading 14.50 (4.77) Nmm/ o ] ranges of motion. The new method for measuring the first MTPJ quasi-stiffness established in the present study serves as a reference and opens up opportunities for future clinical investigations.

Fiber Bragg grating sensors for monitoring of physical parameters: a comprehensive review

“…Assessing the movement of joint in body is crucial in medical practice and the latest study was conducted where stiffness and angular displacement of first metatarsophalangeal joint was recorded using FBG and load cell. 153 This technique opens up future investigation in the medical field due to enhanced accuracy. For accurate results, high resolution is required, which can be obtained using wavelength scanning laser, 154 which works on scanning of radio frequency signal.…”

Within-Day and Between-Day Reliability of a FBG-Based Smart Sock System for Measuring Active Toe Flexion Displacement of the Hallux

“…After fitting the FBG sensors embedded smart sock system, the participant laid horizontally on an examination table with the face and torso facing up and her legs straightened. 8,17 The participant's left foot was supported by a customized wooden stand to maintain a neutral posture (Fig. 1).…”

“…10 Specific to biomechanics of the human body, FBG-based sensors have demonstrated promising results in measuring ground reaction force during human gait, 14 facilitating active knee orthosis for rehabilitation, 15 and assessing the first toe joint quasi-stiffness. 16,17 When developing new sensors or measurement systems, it is first necessary to validate the new measurements against current gold standard or best practice. The FBG-based smart sock system developed by Leow et al 8 had reasonable accuracy within 1 cm in measuring toe flexion displacement as validated in a laboratory setting using 3-D motion capture as the gold standard.…”

Fiber Bragg Gratings for Medical Applications and Future Challenges: A Review

“…Wearables were also proposed for monitoring the mobility of phalanges of hands and feet. An instrumented rubber cable for monitoring plantar dorsiflex was fabricated in [56] whereas a smart glove in [57], and a smart TPU guide in [53] were used for interphalangeal joints movements detection. In [57], an array of fourteen FBGs embedded in PVC was glued in a coiled layout over the interphalangeal joints on the glove upper surface.…”