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bioRxiv · 10.1101/309328

Measuring Clinically Relevant Knee Motions With A Self-Calibrated Wearable Sensor

Hullfish, T. J.·Qu, F.·Stoeckl, B. D.·Gebhard, P. M.·Mauck, R. L.·Baxter, J. R.
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Abstract

Low-cost sensors provide a unique opportunity to continuously monitor patient progress during rehabilitation; however, these sensors have yet to demonstrate the fidelity and lack the calibration paradigms necessary to be viable tools for clinical research. Therefore, the purpose of this study was to validate a low-cost wearable sensor that accurately measured peak knee extension during clinical exercises and needed no additional equipment for calibration. Knee flexion was quantified using a 9-axis motion sensor and directly compared to motion capture data. Peak extension values during seated knee extensions were accurate within 5 degrees across all subjects (RMS error: 2.6 degrees, P = 0.29) but less accurate during sit-to-stand exercises (RMS error: 16.6 degrees, P = 0.48). Knee flexion during gait strongly correlated (0.84 [≤] rxy [≤] 0.99) with motion capture measurements but demonstrated average errors of 10 degrees. This study demonstrated a low-cost sensor that satisfied our criteria: a simple calibration procedure resulting in accurate measures of joint function during clinical exercises, making it a feasible tool for continuous patient monitoring to guide regenerative rehabilitation.

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Hullfish, T. J., Qu, F., Stoeckl, B. D., Gebhard, P. M., Mauck, R. L., Baxter, J. R.. 2018-05-10. Measuring Clinically Relevant Knee Motions With A Self-Calibrated Wearable Sensor. https://doi.org/10.1101/309328

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