Role of High-Resolution Ultrasound in Investigating the Glenohumeral Capsuloligamentous Structures: A New Proposal for an Anterior Approach

Methods and Materials: We first evaluated the accuracy of ultrasound to identify the anterior glenohumeral capsule and to differentiate it from the overlying subscapularis tendon. For this purpose, ultrasound examination was performed in six shoulders from three cadavers with a 18-5 MHz probe and, after the identification of the supposed cleavage plane between the subscapularis tendon and the glenohumeral capsule, 1 to 2 mL green stain were injected between the two structures. After dissecting the shoulder, the presence of the stain in the exact location was verified and the relationship between the anterior capsule, the middle glenohumeral ligament, and the subscapularis tendon was studied. The anterior capsule was then measured in its maximal thickness point underneath the subscapularis tendon in 40 shoulders from 20 healthy volunteers. We finally scanned 10 shoulders of 5 patients with a clinical diagnosis of adhesive capsulitis and 5 patients with shoulder instability, and we verified if their anterior capsule thickness differed significantly from the one of volunteers. When shoulder abduction was tolerated, we also measured the patient’s inferior capsule thickness for comparison.

Results: Cadaver dissections demonstrated the correct location of the stain between the subscapularis tendon and the capsule in all six specimens. No significant difference in anterior capsule thickness was found when comparing the two sides of volunteers. Only five patients tolerated sufficient shoulder abduction to allow the evaluation of the inferior capsule. The anterior glenohumeral capsule was significantly thicker (p < 0.05) in both patients with adhesive capsulitis and shoulder instability.

Conclusion: Ultrasound is able to demonstrate the anterior capsuloligamentous structures of the shoulder and to differentiate them from the overlying subscapularis tendon. The evaluation of the anterior capsule can show pathologic changes in patient with shoulder instability or adhesive capsulitis. These examination results are better tolerated than scanning the inferior capsule because they do not require full shoulder abduction.

Fig. 1 (a) Long axis scan of the subscapularis tendon shows the needle (arrowheads) placed in the cleavage plane (dashed line) between the subscapularis and the anterior capsule. (b) The stain is shown between the two structures. HH, humeral head.

Fig. 2 Longitudinal scan of the subscapularis tendon in a healthy volunteer during measurement of the anterior glenohumeral capsule demonstrates the different echogenicity of the tendon and the capsule. HH, humeral head.

Publication History

Article published online:
17 December 2020