A Method for Calculating Lower Extremity Anatomical Landmark Trajectories Based on Inertial Motion Capture Data

Area of Science:

• Biomechanics
• Human Kinematics
• Motion Capture Technology

Background:

• International Society of Biomechanics (ISB) standards define joint coordinate systems using anatomical landmark trajectories.
• Inertial motion capture (IMC) studies typically focus on joint angles, limiting broader kinematic analysis.
• Calculating precise anatomical landmark trajectories from IMC data remains a challenge.

Purpose of the Study:

• To develop and validate a novel method for determining anatomical landmark trajectories from IMC data.
• To expand the analytical capabilities of IMC beyond joint angle measurements.
• To enable more in-depth human motion analysis using IMC.

Main Methods:

• A new algorithm was developed to compute anatomical landmark trajectories using IMC data.
• Comparative analysis was performed against optical motion capture (gold standard).
• Measurements were collected from 16 healthy volunteers to assess accuracy and reliability.

Main Results:

• The proposed method achieved anatomical landmark trajectory accuracy of 23.4–57.3 mm (5.9–7.6% of segment length).
• Orientation accuracy ranged from 3.3° to 8.1° (less than 8.6% of ROM), comparable to optical systems.
• The IMC method demonstrated accuracy similar to the commercial Xsens MVN system.

Conclusions:

• The developed IMC-based method accurately calculates anatomical landmark trajectories.
• This approach significantly enhances the utility of IMC for comprehensive human kinematic analysis.
• The versatile output format supports advanced motion analysis applications.