Table of Contents
- 01. Rotator Cuff
- 1. Anatomy and Function
- 2. Pathogenesis
- 3. Terminology
- 4. Natural History
- 5. Ultrasound Technique
- 6. Spectrum of Findings
- 7. Ultrasound Pitfalls
- 8. References
- 02. Postoperative Rotator Cuff
- 03. Long Head of Biceps Brachii Tendon
- 04. Bursae
- 05. Joint Spaces
- 1. Acromioclavicular Joint
- 2. Glenohumeral Joint
- 3. Sternoclavicular Joint
- 4. Scapulothoracic
- 5. References
- 06. Fractures
- 07. Os acromiale
- 08. Adhesive Capsulitis
- 09. Deltoid
- 10. Pectoralis Major
- 11. Web Exclusive: Sternocostal Joints
4.2. Subcoracoid Bursa
The subcoracoid bursa is located anterior to the subscapularis muscle and inferior to the coracoid process. Its function is to reduce friction between the coracobrachialis, subscapularis, and short head of the biceps tendons, thus facilitating internal and external rotation of the shoulder.48 The subcoracoid bursa does not communicate with the glenohumeral joint under normal circumstances, but may communicate with the SSB. The percentage of such communication is estimated at 10-55%49-52 and the higher percentage suggest that the communication may be a tiny obliterated remnant that becomes patent when either bursa contains excess fluid.50
4.2.1. Ultrasound Technique
The subcoracoid bursa is not visible at US in healthy individuals. However, its expected location should always be scanned, obtaining sagittal images just inferior to the coracoid process. Because of its deep location, sonographic evaluation may require a lower-frequency curvilinear array probe for adequate visualization.
4.2.2. Spectrum of Ultrasound Findings
Sonographic detection of the subcoracoid bursa is always abnormal (figure 4-24) and more conspicuous during external rotation of the shoulder (video 4-8). Subcoracoid bursa should not be confused with the superior subscapularis recess, which may extend anterior to the subscapularis tendon and mimic subcoracoid bursitis. The distinction is important because fluid detected in the superior subscapularis recess at US represent glenohumeral joint effusion (see figure 5-22), whereas fluid in the subcoracoid bursa indicates bursitis.
The subcoracoid bursa is considered an extension of the subacromial-subdeltoid bursa (SSB) when communication between these two structures does occur, sharing common clinical presentation, pathogenesis, and management (figure 4-25). Because of this potential communication, fluid in the subcoracoid bursa should always raise suspicion for a rotator cuff abnormality. Isolated subcoracoid bursitis is rare but has been implicated as a source of shoulder pain. Because of its rarity, the literature describing isolated subcoracoid bursitis is confined to sporadic case reports, with no specific studies on pathogenesis.
4.2.3. Grading of Subcoracoid Bursitis
As in the case of SSB, we generally do not report measurements of the subcoracoid bursitis. We, however, consider important to inform when a communication between the SSB and subcoracoid bursa is found at US.
4.2.4. Follow-up of Subcoracoid Bursitis
Studies on the follow-up of subcoracoid bursitis are lacking. In the absence of specific data, it is reasonable to consider subcoracoid bursitis as a synonym of subacromial-subdeltoid bursitis for sonographic follow-up purposes.