[Ultrasound evaluation of multidirectional instability of the shoulder].

In a prospective study we evaluated the active a-p translation of the humeral head in the glenoid socket and the passive cranio-caudal translation of the humeral head in relation to the acromion. In 150 healthy volunteers we documented normative data. These results were compared with the data recorded in 34 patients with multidirectional shoulder instabilities. With the arm adducted or in 90 degrees flexion we found no statistically significant differences between volunteers and patients or between the sexes, or between the dominant and the non-dominant extremity in the relationship between the humeral head and the dorsal brim of the glenoid. In 90 degrees abduction and neutral rotation of the arm the dorsal overhang of the humeral head in relation to the dorsal brim of the glenoid was 1.5 mm (+/- 3.5 mm) on the dominant and 1.9 mm (+/- 3.4 mm) on the non-dominant side in the volunteer group. However, in patients with multidirectional shoulder instability the humeral head demonstrated such a high degree of a.-p. translation that we found a ventral overhang of 2.9 mm (+/- 3.7 mm) on the dominant and 0.7 mm (+/- 4.6 mm) on the opposite side. These differences to the volunteer group were statistically highly significant (P less than 0.001). In patients the difference between the dominant and the non-dominant extremity was also significant (P less than 0.05). After active movement into the 90 degree abducted and external rotated position of the arm the differences between volunteers and patients increased, until finally the differences in patients between the dominant and the non-dominant side were highly significant.(ABSTRACT TRUNCATED AT 250 WORDS)