Anatomy:
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Tears:
Tear is indicated by absence of tendon in bicipital groove
Medial dislocation occurs due to coracohumeral ligament tear (transverse humeral ligament is extension of coracohumeral ligament), usually due to forced external rotation
Fluid around biceps tendon:
Usually due effusion in glenohumeral joint rather than primary biceps tendon abnormality
Tears in coracohumoral ligament causes fluid around the intra-articular portion of biceps tendon and tendon may show increased mediolateral motion during rotational movements
Subluxation and dislocation of biceps tendon:
Subluxation: tendon is perched over tip of lesser tuberosity
Dislocation: tendon lies on outer slope of bicepital groove
The most common cause is disruption of subscapularis tendon and coracohumeral ligament, during which the tendon dislocates medially over lesser tuberosity within glenohumeral joint. In subscapularis tear with intact coracohumeral ligament, there is no dislocation. If coracohumeral ligament is torn with intact subscapularis tendon, the tendon is dislocated superficial to subscapularis tendon
US:
Absent tendon in biceptial groove and seen in more medial position
Tendon may be difficult to see if it is deep within glenohumeral joint
Arm in external rotation increases sensitivity of diagnosis
In chronic dislocations, the empty groove may be filled with echogenic fibrous scar tissue mimicking normal tendon. To avoid this pitfall, the tendon should be followed in its entire course In intermittent instability, the tendon moves to-and-fro medially during alternate external and internal rotation of arm
Hour glass biceps:
Mechanical condition affecting intraarticular portion of long head of the biceps tendon leading to pain, locking and limited elevation of shoulder
May be diagnosed on MR
Associated with tendinopathy and partial tears
References:
1. Ostlere S. Imaging the shoulder.Imaging 15:162-173 (2003)
2. Martinoli C et al. US of the Shoulder: Non–Rotator Cuff Disorders. Radiographics. 2003;23:381-401
