Two dimensional ultrasound of the shoulder joint has become a well established diagnostic tool. Difficult interpretation of ultrasonographic findings, however, suggests that ultrasound appears not to be an always reliable method, especially in partial thickness tears. The present study was performed to determine whether the use of three dimensional (3D) sonography further increases the diagnostic yield of ultrasound.

On a total of 22 externally intact appearing rotator cuffs of cadaveric shoulder joints 7 full thickness and 15 partial thickness incisions were carried out on the M. supraspinatus, subscapularis and infraspinatus tendon. The specimens included the humeral head, the glenoid, the joint capsule and periarticular tendons.

Ultrasound was performed on the shoulder specimens in a water basin with a 8.5 MHz curved array transducer (Combison 530D, Kretztechnik, Zipf, Austria).

With three dimensional ultrasound rotator cuff lesions were more often correctly diagnosed (sensitivity of 77 %) than with conventional 2D sonography (sensitivity of 64 %). Specificity was 85 % and 69 %, respectively. In partial thickness tears in particular, 3D imaging was the superior method reaching a sensitivity and specifity of 73% and 77%, respectively compared to 53% and 61%, respectively with 2D ultrasound.

The use of three dimensional ultrasound appears to have a higher diagnostic yield in partial thickness tears. One advantage is that the examiner must not move the transducer to obtain other planes. Changes in echogenicity can be observed in the complete volume and in any plane. In the diagnosis of partial tears these changes enabled the examiner to distinguish intact from ruptured tissue.