Continuous mobile measurement of camptocormia angle using four accelerometers

Area of Science:

• Biomedical Engineering
• Clinical Biomechanics
• Rehabilitation Technology

Background:

• Camptocormia, a severe spinal flexion deformity, poses challenges for continuous monitoring outside clinical settings.
• Accurate assessment of the camptocormia angle (CA) is crucial for understanding disease progression and treatment efficacy.
• Existing monitoring methods are often limited to laboratory environments, restricting real-world data collection.

Purpose of the Study:

• To introduce and evaluate a novel wearable system for continuous, out-of-laboratory monitoring of the camptocormia angle (CA).
• To assess the feasibility and accuracy of using inertial measurement unit (IMU) sensors for CA measurement using both malleolus and perpendicular methods.
• To compare the performance of the IMU system against a camera-based reference system.

Main Methods:

• Development of a customized system with four IMU sensors for wearable, continuous CA recording.
• Evaluation of both consensual malleolus and perpendicular assessment methods for CA measurement.
• Testing the system's practicality across various activities in a simulated Parkinson disease posture using a healthy volunteer.
• Comparison of IMU-derived CA measurements against a camera-based reference system.

Main Results:

• The IMU system demonstrated overall root mean squared errors (RMSE) of 4.13° for the malleolus method and 2.71° for the perpendicular method compared to the reference system.
• Patient-specific calibration during standing with forward lean significantly improved accuracy, reducing RMSE to 2.45° (malleolus) and 1.68° (perpendicular).
• The system proved wearable, mobile, and practical for measuring CA during diverse activities outside the laboratory.

Conclusions:

• The proposed IMU-based system offers a novel and effective approach for continuous camptocormia angle monitoring outside laboratory settings.
• This technology enables practical, real-world assessment of spinal flexion deformities, including the first implementation of the malleolus method with IMUs.
• The system holds significant promise as a tool for monitoring camptocormia progression and facilitating remote patient care at home.