[Echography of the supraspinatus tendon: forced passive adduction maneuver]

Imaging methods are essential for a correct diagnostic approach and treatment planning in patients with a painful shoulder. More than any other, the supraspinatus tendon is often involved in impingement syndrome and sonography (US) is now the procedure of choice for the first assessment of rotator cuff tears. We suggest a supraspinatus tendon passive stress maneuver drawing the tendon out from underneath the acromion and showing a longer portion of the tendon that would otherwise be masked by the acromion.

Twenty normal subjects (10 men and 10 women, aged 20 to 46 years, mean age: 32 years) and two patients with shoulder pain underwent shoulder US with real time equipment and a 7.5 MHz linear array transducer. US images were acquired with the subjects allowed to rest with their arm in neutral position and during supraspinatus tendon passive adduction stress maneuver (with the arm first abducted by placing a plastic cylinder device under the armpit, then submitted to passive forced adduction). All US scans were performed along the longitudinal axis of the tendon. The length of the supraspinatus tendon was measured from its insertion on the greater tuberosity of the humerus to the lateral edge of the acromion. Measurements were made in neutral position and during the stress maneuver and, for each subject, the increased length of the displayed portion was obtained as the difference between the two measurements.

In neutral position at rest, the displayed portion of the supraspinatus tendon was 21 mm long on the average (range: 11 to 31 mm). The average increase, namely the tendon portion recovered from the acromial acoustic shadow, was 4.5 mm (range: 2 to 10 mm). In two patients the stress maneuver permitted better visualization of tendon tear, which finding was confirmed at MRI. The results of our study so far seem to suggest that the passive adduction stress maneuver permits to visualize a longer portion of the supraspinatus tendon without affecting its anatomical alignment and could thus be useful in US studies of the rotator cuff.