Development of a clinically adoptable joint coordinate system for the wrist

Area of Science:

• Biomechanics
• Orthopedics
• Human Movement Analysis

Background:

• Kinematics are crucial for understanding joint biomechanics in clinical and research settings.
• Current International Society of Biomechanics (ISB) recommended methods for wrist joint coordinate system (JCS) construction are challenging for in vivo application.

Purpose of the Study:

• To evaluate alternative JCSs for wrist kinematics against ISB recommendations.
• To assess landmark digitization repeatability, coordinate frame creation repeatability, and secondary rotations during planar motion.

Main Methods:

• Compared 408 JCSs to the ISB standard using landmark digitization and coordinate frame creation repeatability metrics.
• Analyzed secondary rotations during planar motion for different JCS definitions.
• Identified specific forearm frame definitions to avoid due to excessive secondary rotations.

Main Results:

• No significant differences were found between the ISB JCS and 338 of the tested alternative JCSs.
• Forearm frames using the epicondylar vector for the YZ plane resulted in clinically significant secondary rotations.
• A specific JCS utilizing radial/ulnar styloid, epicondyles, metacarpal heads, and third metacarpal base is recommended.

Conclusions:

• Numerous alternative JCSs can be used interchangeably with the ISB standard for wrist kinematics.
• The proposed JCS offers a practical and repeatable method for in vivo kinematic analysis.
• Avoid forearm JCS definitions based on the epicondylar vector to prevent erroneous kinematic data.