A Spinal Motion Measurement Protocol Utilizing Inertial Sensors Without Magnetometers.

Area of Science:

• Biomechanics
• Medical Instrumentation
• Human Motion Analysis

Background:

• Accurate measurement of spinal motion is crucial for clinical assessment and rehabilitation.
• Traditional motion capture systems can be cumbersome and expensive.
• Inertial Measurement Units (IMUs) offer a potential portable and cost-effective solution for motion tracking.

Purpose of the Study:

• To present and validate an instrumentation approach for spinal motion measurement using IMUs.
• To assess the accuracy of IMU-based spinal motion tracking against an optical motion capture system.
• To evaluate the system's efficacy in measuring trunk-pelvis relative orientation during key spinal movements.

Main Methods:

• Two IMUs were affixed to the posterior pelvis and superior trunk of participants.
• Participants performed standardized spinal motions: flexion-extension, side bending, and rotation.
• IMU-derived motion data was concurrently recorded and compared with a gold-standard optical motion capture system.

Main Results:

• The IMU system demonstrated high accuracy in tracking trunk-pelvis relative orientation.
• Minimal deviations were observed between IMU and optical motion capture measurements (RMSE < 2°, r > 0.84).
• The proposed instrumentation approach proved effective across all tested spinal motions.

Conclusions:

• The validated IMU-based system provides an accurate and effective method for spinal motion measurement.
• This approach offers a practical alternative for assessing spinal kinematics in research and clinical settings.
• The findings support the use of IMUs for non-invasive, reliable spinal motion analysis.