Subcoracoid impingement exacerbates pain and scapular dysfunction in full-thickness rotator cuff tears

Area of Science:

• Orthopedics
• Sports Medicine
• Biomechanics

Background:

• Subcoracoid impingement often co-occurs with subacromial impingement in rotator cuff tear patients.
• The specific impact of subcoracoid impingement on full-thickness rotator cuff tears (FT-RCT) is not well understood.
• Investigating differences between FT-RCT patients with and without subcoracoid impingement is crucial.

Purpose of the Study:

• To compare clinical and biomechanical characteristics of FT-RCT patients with and without subcoracoid impingement.
• To identify differences in pain, shoulder function, humeral head migration, scapular kinematics, and muscle activity.

Main Methods:

• Compared 22 FT-RCT patients with subcoracoid impingement to 25 FT-RCT patients without it.
• Assessed humeral head migration via acromiohumeral distance using ultrasonography (USG).
• Evaluated shoulder range of motion, pain, function, scapular kinematics, and muscle activity (serratus anterior [SA], teres major [TM]) using motion tracing and electromyography.

Main Results:

• The subcoracoid impingement group reported higher pain levels and greater superior humeral head migration during abduction.
• This group showed decreased scapular upward rotation during arm lowering.
• Reduced serratus anterior (SA) and teres major (TM) muscle activation was observed during arm raising and lowering.

Conclusions:

• FT-RCT patients with subcoracoid impingement experience slightly higher pain and increased superior humeral head migration.
• Reduced scapular upward rotation and impaired SA/TM muscle function may worsen symptoms.
• While statistically significant, observed differences require cautious clinical interpretation due to magnitude.