Joint rotation between two attitudes in the spherical rotation coordinate system

Area of Science:

• Biomechanics
• Human Movement Analysis
• Clinical Kinematics

Background:

• Human movement analysis often requires quantifying three-dimensional (3D) joint rotations.
• Most human movements occur between two non-neutral positions, posing challenges for traditional analysis methods.
• Existing methods may lack clinical applicability or mathematical rigor for non-neutral starting points.

Purpose of the Study:

• To present a novel, clinically relevant method for determining 3D joint rotations between two non-neutral attitudes.
• To develop a sequence-independent mathematical framework for analyzing joint rotations.
• To facilitate easier understanding and application of joint rotation analysis in clinical practice.

Main Methods:

• A two-step rotation method within a spherical rotation coordinate system was employed.
• Three spherical rotation angles, aligned with clinical descriptions, were utilized.
• Mathematical proofs confirmed the sequence independence of the proposed rotation angles.

Main Results:

• The developed method accurately determines 3D joint rotations from non-neutral starting positions.
• The sequence-independent nature of the rotation angles simplifies complex movement analysis.
• Numerical examples involving humeral rotations demonstrated the method's effectiveness across diverse movement patterns.

Conclusions:

• The proposed method offers a practical and mathematically sound approach to analyzing 3D joint rotations between non-neutral attitudes.
• This technique enhances the understanding of human movement biomechanics for clinicians.
• The findings support the integration of this method into clinical practice for improved patient assessment and treatment planning.