A method for the measurement of three-dimensional scapular movement

Area of Science:

• Orthopedics
• Biomechanics
• Sports Medicine

Background:

• Shoulder complex disorders often involve altered scapular motion patterns.
• Radiographic methods are typically required for accurate scapular motion measurement.
• Non-invasive, reliable techniques for assessing 3D scapular kinematics are needed.

Purpose of the Study:

• To develop and validate a novel technique for measuring the three-dimensional (3D) motion of the scapula during arm movements.
• To assess the clinical reliability and suitability of the developed system for studying shoulder pathology.

Main Methods:

• A three-pointed locator was designed to attach to three bony landmarks on the scapula: acromial angle, inferior angle, and root of the scapular spine.
• An electromagnetic movement sensor (Isotrak) measured the spatial orientation of the locator relative to the trunk.
• Scapular plane rotations and out-of-plane angles were measured during arm abduction.

Main Results:

• The developed system demonstrated clinically reliable measurements of scapular motion.
• Measurements of scapular plane rotations during abduction showed good agreement with existing published data.
• Variations in out-of-plane angle measurements were noted, potentially due to deltoid muscle contraction affecting acromion contact.

Conclusions:

• The novel technique using a 3-pointed locator and electromagnetic sensor is suitable for clinical application.
• This system facilitates the study of 3D scapular kinematics in patients with shoulder pathology.
• Further refinement may be needed to optimize out-of-plane angle measurements during dynamic muscle contraction.