A 48-year-old female presented with left shoulder pain, particularly during abduction/overhead activity.
Ultrasound demonstrates severe focal degenerative tendinopathy involving the anterior portion of the supraspinatus tendon.
At this level, the supraspinatus tendon measures approximately 11.1 mm in thickness, compared with an expected thickness of approximately 5–7 mm at this location. The abnormality is distinctly focal rather than diffuse.
The affected tendon segment is markedly hypoechoic and substantially thickened. The degree of hypoechogenicity is pronounced, particularly towards the bursal surface. Due to the severity of the structural tendon abnormality, associated small partial-thickness bursal-sided tears cannot be excluded sonographically.
The marked focal increase in tendon volume considerably reduces the available subacromial space. This degree of thickening is therefore likely to contribute to mechanical subacromial impingement during active shoulder abduction, particularly if corresponding dynamic narrowing or painful restriction is demonstrated clinically or during dynamic ultrasound assessment.
1. Final diagnosis
Severe focal degenerative tendinopathy of the anterior supraspinatus tendon, with marked thickening to approximately 11.1 mm and pronounced hypoechogenicity. Small associated partial-thickness bursal-sided tears cannot be excluded.
2. Differential diagnosis
The findings primarily represent advanced focal supraspinatus tendinopathy. The marked bursal-sided hypoechogenicity raises the possibility of superimposed partial-thickness bursal-sided tearing. If the tendon architecture remains difficult to characterise because of the severity of the degenerative changes, additional imaging may help differentiate severe tendinosis from a discrete partial-thickness tear.
3. Teaching points
Supraspinatus tendinopathy may produce substantial focal tendon thickening in addition to loss of the normal fibrillar echotexture. Severe hypoechogenicity can make small partial-thickness tears difficult to distinguish from advanced degenerative tendon change. Tendon thickness should also be considered mechanically: pronounced enlargement of the supraspinatus tendon can reduce the functional subacromial space and contribute to impingement during active abduction.
4. Injury/disease information
Degenerative supraspinatus tendinopathy represents structural deterioration of the rotator cuff tendon and may range from focal tendinosis to partial-thickness tearing. Marked tendon swelling can increase mechanical contact beneath the acromion during elevation of the arm. Dynamic ultrasound assessment during active abduction can be useful to correlate structural tendon enlargement with subacromial passage and reproduction of symptoms. MRI may be considered when accurate characterisation of a suspected partial-thickness tear would alter further management.
Marc is founder of, and trainer at, SonoSkills. SonoSkills is an organization dedicated to MSK ultrasound education. He's also an MSK Sonographer at EchoConsult in Roermond, the Netherlands.
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