Multisegment Kinematics of the Spinal Column: Soft Tissue Artifacts Assessment

Area of Science:

• Biomechanics
• Human Motion Analysis
• Spinal Kinematics

Background:

• Accurate assessment of intersegmental spinal column angles during trunk motion is crucial.
• Soft tissue artifacts (STAs) introduce significant errors in marker-based motion capture of bony landmarks.
• Quantifying and correcting STA-induced errors is essential for reliable spinal kinematics.

Purpose of the Study:

• To perform an uncertainty analysis and estimate errors induced by STAs in intersegmental spinal angles.
• To develop and apply an error model for correcting STA-induced inaccuracies in trunk motion analysis.
• To investigate the impact of STAs on spinal angles in different trunk bending directions.

Main Methods:

• Modeled STA using multivariate Gaussian distribution based on relative marker-bony landmark displacement measurements.
• Assumed linear growth of error with trunk bending angle.
• Applied the error model to 3D trunk motion data from 11 subjects using a 7-segment rigid-body model and 23 markers.

Main Results:

• STAs minimally affected sagittal plane angles (<16%).
• STAs considerably corrupted coronal plane angles (59%–551% error).
• STAs significantly impacted transverse plane angles (up to 161% error).

Conclusions:

• The proposed error suppression technique effectively compensates for STA-induced errors.
• Accurate spinal kinematics measurements, particularly in coronal and transverse planes, are achievable with this method.
• The technique enhances the reliability of spinal motion data for clinical decision-making.