Scapular and humeral elevation coordination patterns used before vs. after Reverse Total Shoulder Arthroplasty

Area of Science:

• Orthopedics
• Biomechanics
• Rehabilitation

Background:

• Scapulohumeral coordination is crucial for effective arm elevation.
• Reverse Total Shoulder Arthroplasty (RTSA) aims to restore shoulder function, but its impact on scapulohumeral rhythm (SHR) requires further investigation.
• Understanding kinematic changes post-RTSA is vital for optimizing patient outcomes.

Purpose of the Study:

• To compare scapulohumeral coordination before and after RTSA during arm elevation.
• To analyze the effects of different shoulder rotations (neutral, external, internal) on SHR.
• To investigate changes in scapulothoracic upward rotation and SHR post-RTSA.

Main Methods:

• 11 patients (12 shoulders) undergoing RTSA were assessed before and after surgery.
• Optical motion capture measured humerus and scapula kinematics during scapular plane arm elevation.
• One Dimensional Statistical Parametric Mapping (SPM) and paired t-tests analyzed kinematic data.

Main Results:

• SHR significantly increased after RTSA during arm elevation with external (p=0.018) and internal (p<0.001) rotation.
• A non-significant trend of increased SHR was observed with neutral rotation (p=0.182).
• Participant-specific kinematic patterns varied, with some showing increased and others decreased scapulothoracic motion.

Conclusions:

• RTSA positively influences scapulohumeral rhythm, particularly in external and internal rotation.
• Post-RTSA SHR values were comparable to previous studies on RTSA patients but lower than in healthy individuals.
• Individualized kinematic responses highlight the need for tailored rehabilitation strategies post-RTSA.