Infraspinatus tendon tears are rotator cuff injuries affecting the infraspinatus tendon generally associated with other rotator cuff tears and are usually due to degenerative processes, trauma, or constant overhead motion strain ¹.

Epidemiology

Isolated full-thickness infraspinatus tendon tears are very uncommon ². They are usually associated with supraspinatus tendon tears.

Clinical presentation

Patients will present with shoulder pain and tenderness along the infraspinatus tendon. They might present with a weakness in the affected arm and a limited range of motion.

Associations

Associated conditions include:

• supraspinatus tendon tear

• subscapularis tendon tear

• proximal biceps tendon injury

• acromioclavicular joint osteoarthritis

Pathology

Classification

A modification of the original Codman classification may be used to categorise tears:

• full-thickness tear 

  • Fosbury flop tear

• partial-thickness tear

  • ​intrasubstance tear

  • articular-sided tear

    • rim rent tear: articular surface tear of the footprint

    • tendon delamination or interstitial tear

    • cleavage tear: tendon delamination with fluid signal intensity filling the gap

  • bursal-sided tear

• critical zone tear: partial or full-thickness

Radiographic features

Plain radiograph

Calcific tendonitis around the greater tubercle may be seen.

Joint effusion and loss of the acromiohumeral interval could be seen in massive rotator cuff tears.

Ultrasound

Ultrasound can be considered for initial assesement of the infraspinatus tendon. Although it is sufficient for the diagnosis of full thickness tears, some partial tears may be underdiagnosed.

MRI

MRI is the modality of choice in the diagnosis and the pre-operative planning of infraspinatus tendon tears as it demonstrates the tear, it's location, size and all associated lesions.

Radiology report

The radiological report should include a description of the following ³:

• location and size of the tear

• tear pattern and extent

• tendon retraction

• rotator cuff associated tears

• level of muscle fatty degeneration

• acromioclavicular joint osteoarthritis

Treatment and prognosis

Infraspinatus tendon tears could be managed conservatively or surgically, based on the patient age, size of tear, activity level, and mechanism of tear ⁴.

Differential diagnosis

Possible considerations on low resolution modalities include

• supraspinatus tendon tear (inferior margin)

• teres minor tendon tear