[Coraco-humeral space and rotator cuff tears]

Area of Science:

• Orthopedic surgery
• Radiology
• Anatomy

Background:

• Anterior or subcoracoid impingement is often cited but lacks precise clinical, radiological, and anatomical definitions.
• Understanding factors influencing the subcoracoid space (SCS) is crucial for diagnosing and managing rotator cuff tears.

Purpose of the Study:

• To investigate the factors influencing the subcoracoid space (SPS) in patients with rotator cuff tears.
• To clarify the relationship between rotator cuff tear characteristics and SCS dimensions.

Main Methods:

• Analysis of 206 shoulders with full-thickness rotator cuff tears using pre-operative arthro-CT scans.
• Measurement of the SubCoracoïd Space (SCS) as the shortest distance between the coracoid process and humeral head.
• Classification of rotator cuff tears into three groups based on affected tendons (supraspinatus, infraspinatus, subscapularis) and grading muscle degeneration.

Main Results:

• SCS narrowing showed a significant relationship with symptom duration and non-traumatic onset.
• Isolated subscapularis tears (Group 2) did not significantly reduce SCS compared to supraspinatus tears (Group 1).
• Large tears involving subscapularis and infraspinatus (Group 3) showed the highest incidence of SCS narrowing (27%), with an average SCS of 7.7 mm.
• Fatty degeneration of the subscapularis and infraspinatus muscles strongly correlated with SCS narrowing (p < 10-4 and p = 0.0004, respectively).
• The long head of the biceps did not influence SCS.

Conclusions:

• Isolated subscapularis tears do not mechanically cause tendon rupture or SCS narrowing.
• SCS narrowing is primarily a consequence of large cuff tears involving both subscapularis and infraspinatus tendons.
• Muscular degeneration of the infraspinatus and subscapularis, along with complete infraspinatus tears, are necessary conditions for SCS narrowing, suggesting anterior humeral head translation.