[Acute instability of the shoulder in athletes. The role of magnetic resonance in therapy planning].

Magnetic resonance imaging (MRI) of the shoulder was performed to evaluate both the actual role of this technique in the study and staging of acute shoulder instability, and its potentials as diagnostic tool, with particular reference to treatment planning. Seventeen athletes with acute shoulder instability were examined. All MRI examinations, subsequent to plain radiographs, were performed within 48 hours from the traumatic event. After MRI examination, 14 patients underwent physiotherapy (2 cases were subsequently submitted to arthrotomy), and only 3 cases underwent surgical treatment in the acute phase (2 arthrotomies and 1 arthroscopy). These cases, submitted to MRI in the acute phase and subsequently to surgery, showed anterior glenoid labrum involvement with good evidence of associated skeletal lesions (Hill-Sachs lesions in 1); changes in the inferior glenohumeral ligament complex (2 cases) were also observed. In the other examined cases, MRI always provided accurate information on the glenoid labra and the anterior capsular mechanism. When the superior glenohumeral ligament was investigated (9 cases of 17), no alterations were observed. Acting as natural contrast, the presence of joint effusion allows good visualization, on T1-weighted sequences, of the structures involved by the traumatic events. Contrast resolution improvement could be obtained by employing gradient-echo T2 weighted sequences, which proved to be quite valuable for a correct depiction of the lesions involving the inferior glenohumeral ligament complex. In conclusion, MRI can be considered as a valuable diagnostic method for the early evaluation of the acute shoulder instability, since it provides information of the utmost importance for the subsequent therapeutical approach.