Arthrography in acute shoulder dislocations.

Abstract

Arthrography of the shoulder was performed on 50 patients with acute traumatic shoulder dislocations. The mean interval between injury and arthrogram was 2.3 days, with a median interval of one day. Anterior dislocations occurred in 96% of patients, and posterior dislocations in 4%. Initial dislocations were present in 74%, and recurrent dislocations in 26%. The most frequent abnormality identified or arthrograms was an enlarged but intact shoulder capsule (58%), most commonly seen in shoulders subject to recurrent dislocations (77%). Shoulder joint capsular tears or disruptions were seen in 48% of the patients. The next most common lesion was fracture (52%), identified on standard roentgenograms. These included Hill-Sachs lesions (28%), greater tuberosity fractures (22%), and coracoid fractures (2%). Ruptures of the rotator cuff, present in 28% of the cases (14 patients), occurred more frequently in initial dislocations (62%) than in recurrent ones (36%). The high frequency of enlarged intact shoulder capsules, even after an acute initial joint dislocation (58%), suggests that the humeral head does not routinely rupture the capsule during dislocation, but rather tears the glenoid labrum at its bony attachment and dislocates subperiosteally, dissecting a false pouch below the periosteum and under the subscapularis.