Robust Longitudinal Ankle Edema Assessment Using Wearable Bioimpedance Spectroscopy

Area of Science:

• Biomedical Engineering
• Wearable Technology
• Physiology

Background:

• Ankle edema is a common issue in acute injuries and rehabilitation.
• Longitudinal tracking of ankle edema is crucial for recovery assessment.
• Existing methods for edema measurement have limitations in accuracy and practicality.

Purpose of the Study:

• To present a robust methodology for longitudinal ankle edema tracking using bioimpedance spectroscopy (BIS).
• To introduce a novel, miniaturized wearable BIS system with improved accuracy and lower power consumption.
• To develop a differential measurement technique addressing key challenges in BIS-based edema assessment.

Main Methods:

• Designed a miniaturized wearable BIS measurement system with a novel calibration method.
• Employed a differential measurement technique to mitigate variability in electrode placement, posture, and intersubject differences.
• Validated the system and technique through bench-top testing, an ex vivo cadaveric limb model, and a cohort of 11 human subjects.

Main Results:

• Bench-top testing showed low error (0.4 Ω real, 0.54 Ω imaginary) and high resolution (0.2 Ω) for BIS measurements.
• The wearable system and differential technique demonstrated feasibility in both ex vivo and in vivo human studies.
• Successful proof-of-concept validation was achieved in healthy controls and subjects with acute ankle injuries.

Conclusions:

• The developed hardware and differential measurement technique enable robust, long-term quantification of ankle edema.
• This technology has the potential to significantly improve decision-making in rehabilitation and return-to-activity planning.
• Personalized rehabilitation strategies can be tailored based on continuous, objective edema data.