Three-dimensional clavicular and acromioclavicular rotations during arm abduction using vertically open MRI

Area of Science:

• Orthopedics
• Biomechanics
• Medical Imaging

Background:

• Precise 3D motion of the clavicle and acromioclavicular joint during arm abduction remains incompletely understood.
• Previous studies have not fully characterized the complex kinematics involved.

Purpose of the Study:

• To analyze the three-dimensional (3D) kinematics of the clavicle and acromioclavicular joint during arm abduction.
• To quantify clavicular and scapular movements relative to anatomical landmarks.

Main Methods:

• Utilized 3D Magnetic Resonance Imaging (MRI) from a vertically open MRI scanner.
• Acquired images of 14 shoulders across seven abducted arm positions.
• Employed volume-based registration for evaluating 3D bone movements.

Main Results:

• Clavicular motion relative to the lung: 30.6° retraction, 7.3° elevation, 33.2° posterior axial rotation.
• Scapular motion relative to the clavicle: 15.6° protraction, 21.5° upward rotation, 22.2° posterior tilting.
• Demonstrated substantial rotational movements in both clavicular and scapular kinematics.

Conclusions:

• Successfully described detailed 3D clavicular and acromioclavicular joint motion, including clavicular axial rotation.
• The study highlights significant degrees of rotation in both clavicular and scapular movements during arm abduction.