66-year-old patient presenting with shoulder pain during abduction and overhead activity. Symptoms may be progressive. Clinical context suggests possible prior rupture of the long head of the biceps tendon. Further details not provided.
Ultrasound examination of the shoulder demonstrates a small articular-sided partial thickness tear of the supraspinatus tendon at the level of the anatomical neck (collum anatomicum). The tear appears as a focal hypoechoic defect on the articular side with localized disruption of the fibrillar pattern.
The supraspinatus tendon shows mild tendinopathy in the dysrepair phase, with slight thickening and heterogeneous echotexture.
There is mild distension of the subacromial-subdeltoid (SASD) bursa, consistent with mild bursitis.
The combined thickening of the supraspinatus tendon and SASD bursa results in relative narrowing of the subacromial space. Dynamic ultrasound assessment during guided active abduction demonstrates primary impingement, with mechanical compression of the supraspinatus tendon and bursa beneath the acromion.
Additionally, it is important to consider the biomechanical role of the long head of the biceps tendon. In cases of complete rupture, the loss of its caudal stabilizing effect on the humeral head may lead to cranial migration of the humeral head. This can reduce the acromiohumeral distance and contribute to progressive subacromial impingement symptoms.
1. Final diagnosis
Small articular-sided partial thickness tear of the supraspinatus tendon with mild dysrepair-phase tendinopathy and mild SASD bursitis, resulting in dynamic primary subacromial impingement. Likely contributing biomechanical factor: absent or deficient long head of the biceps tendon.
2. Differential diagnosis
Consider isolated supraspinatus tendinopathy without tear, bursal-sided partial tear, or internal impingement. Evaluation of associated rotator cuff and labral pathology may require MRI.
3. Teaching points
Articular-sided partial tears are often subtle and best visualized as focal hypoechoic defects at the deep tendon surface. Even mild tendon and bursal thickening can result in clinically significant impingement. The long head of the biceps tendon contributes to humeral head depression; its absence may promote cranial migration and secondary impingement.
4. Injury/disease information
Partial thickness rotator cuff tears commonly occur on the articular side due to increased mechanical stress and relative hypovascularity. Subacromial pain syndrome is often multifactorial, involving tendon degeneration, bursitis, and altered shoulder biomechanics. Loss of stabilizing structures, such as the long head of the biceps tendon, can exacerbate impingement by reducing the subacromial space.
Marc is founder of, and trainer at, SonoSkills. SonoSkills is an organization dedicated to MSK ultrasound education. He's also an MSK Sonographer at the Laurentius Hospital in Roermond, the Netherlands.
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