A flexible wearable sensor for knee flexion assessment during gait

Area of Science:

• Biomechanics
• Wearable Technology
• Medical Sensor Technology

Background:

• Gait analysis is crucial for diagnosing movement disorders but traditionally confined to laboratory settings.
• There is a growing need for in-home, long-term gait assessments facilitated by wearable technology.
• Current methods often rely on cumbersome laboratory equipment, limiting real-world application.

Purpose of the Study:

• To validate a novel wearable sensor system for measuring peak knee sagittal angles during gait.
• To assess the accuracy and reliability of the sensor compared to a gold standard system.
• To explore the potential of wearable sensors for unobtrusive, long-term gait monitoring.

Main Methods:

• A novel wearable sensor system using flexible conductive polymer and wireless acquisition was developed.
• Sixteen healthy volunteers underwent gait assessments with simultaneous data collection from the sensor and a 10-camera motion capture system.
• Sensor data was calibrated to angular measures, and peak knee flexion angles were compared using RMSE, absolute error, Bland-Altman plots, and ICCs for reliability.

Main Results:

• The wearable sensor demonstrated high accuracy, with an absolute error of 0.35(±2.9°) and RMSE of 1.2(±0.4)° compared to the gold standard.
• Excellent agreement was observed between the sensor and the reference system, with most data within the limits of agreement.
• The sensor exhibited high test-retest reliability, indicated by intra-class correlation coefficients (ICCs) greater than 0.8.

Conclusions:

• The validated wearable sensor system accurately monitors knee peak sagittal angles with minimal error.
• The system shows high reliability and agreement with gold-standard methods, suitable for clinical use.
• This unobtrusive wearable device holds significant potential for discreet, long-term gait analysis in real-world settings.