Validity And Reliability Of Inertial Measurement Units For Pelvic Orientation Assessment: A Systematic Review

Area of Science:

• Biomechanics
• Wearable Technology
• Sports Science

Background:

• Pelvic orientation is crucial for analyzing gait, posture, and athletic performance.
• Laboratory-based motion capture is accurate but expensive and inaccessible.
• Inertial Measurement Units (IMUs) present a portable alternative, but their use requires careful consideration of placement, calibration, and sensor-fusion protocols.

Purpose of the Study:

• To systematically review the validity and reliability of IMU-based pelvic orientation assessment.
• To evaluate IMU performance during functional and sport-specific tasks compared to optical motion capture.
• To identify factors influencing IMU accuracy and reliability in different contexts.

Main Methods:

• Systematic literature search of PubMed, Web of Science, and IEEE Xplore.
• Inclusion of studies assessing pelvic orientation (tilt, obliquity, rotation) using IMUs against optical motion capture.
• PRISMA guidelines followed for reporting; methodological quality assessed using a 12-item tool.

Main Results:

• Pelvic tilt demonstrated high accuracy (RMSE 0.2°-4.9°), while obliquity and rotation showed greater variability (RMSE up to 6°-11° during high-speed running).
• IMUs showed good-to-excellent reliability (ICC 0.87-1.00) during continuous activities.
• Poor reliability was noted for pelvic tilt in post-total hip arthroplasty patients (ICC = 0.08).

Conclusions:

• IMUs are valuable for pelvic orientation measurement, especially in controlled settings with sacrum-based placement.
• Validity is less consistent for pelvic obliquity/rotation, high-speed movements, and clinical populations.
• Standardization of protocols, improved reporting, and further research are needed to optimize IMU application in diverse scenarios.