[Long biceps brachii instability. Role of ultrasonography]

Dislocation of the long head of biceps tendon, including subluxation to displacement out of the bicipital groove, is an uncommon cause of shoulder pain. We investigated the role of US in the diagnosis of this condition.

We examined eight patients with dislocation of the long head of biceps tendon: seven had a displaced, and one a subluxated tendon. All patients had early radiographic and US studies of the shoulder; then, three (37%) were submitted to CT-arthrography and two (25%) to MRI. US was performed at 7.5-13 MHz frequency, CT-arthrography with a volumetric acquisition technique and MRI with a surface coil at 1.5 T. Three patients with tendon dislocation had surgical confirmation of the diagnosis.

Dislocation of the long head of biceps tendon was always diagnosed with US in all our eight patients; CT-arthrography and MRI confirmed the US findings. In the patient with subluxation of the long head of biceps tendon, US showed the tendon displaced over the lesser tuberosity whereas, in the 7 cases of complete luxations, the groove was empty and the tendon displaced medially. At CT-arthrography, the tendon was well outlined by contrast medium within its sheath. In dislocations, it was close to the anterior aspect of the humeral head. In two cases of dislocation, MRI showed both the empty bicipital sulcus and the medial tendon displacement. The subscapularis tendon tear was always associated with tendon dislocation; a supraspinatus tendon tear was observed in 6 cases.

When imaging a painful shoulder, we should investigate the integrity and course of the long head of biceps tendon. In clinical practice, dislocation of this tendon can be reliably diagnosed with US. CT-arthrography and MRI should be used only to supplement inconclusive US studies.