Sonography of the teres minor: A study of cadavers

OBJECTIVE. The purpose of our study was to evaluate in cadavers the ability of high-resolution sonography to identify both the normal tendinous insertion and tears of the teres minor. MATERIALS AND METHODS. The teres minor insertion in five cadaveric shoulders was imaged, and methylene blue dye was injected into both the superior and inferior margins of the teres minor insertion by experienced musculoskeletal radiologists using a 10-5-MHz linear array transducer. Afterward, posterior shoulder dissection was performed. In another group of 11 cadaveric shoulders, an artificial tear was created at the teres minor insertion in six shoulders, and a sham procedure was performed in the remaining five shoulders arthroscopically. After arthroscopy, the teres minor insertion of each shoulder was imaged, and the accuracy of sonography for detecting a tear was evaluated. RESULTS. The dye was injected correctly into both the superior and inferior margins of the teres minor insertion in all five cadaveric shoulders. All six artificial tears were successfully detected on sonography. Four of the five specimens with the sham procedure were identified as having a normal teres minor insertion. One was misinterpreted as a tear. CONCLUSION. Sonography can reliably be used to identify the teres minor insertion and to detect tears of the teres minor muscle-tendon unit.