Forty-four patients, ranging in age from 17 to 57 years (average, 32), were evaluated an average of 4 years (range, 2 to 9) after surgical reconstruction for Allman-Tossy Grade III acromioclavicular dislocations. Twenty-seven patients underwent repair for acute injuries (< 3 weeks after injury) and 17 patients underwent reconstructions for chronic injuries (> 3 weeks). Coracoclavicular fixation with heavy nonabsorbable sutures was used to correct superior displacement in all cases. In addition, transfer of the coracoacromial ligament to the distal clavicle was performed in 15 of the 27 early repairs and 17 of the 17 late reconstructions. Overall, 26 of 27 (96%) early repairs and 13 of 17 (77%) late reconstructions achieved satisfactory results. There was a trend for better results and return to sports or heavy labor with early repairs; however, this was not statistically significant (P = 0.065). When the results of early repairs were compared with those of late reconstructions performed more than 3 months after injury, the results of the shoulders undergoing early repair were significantly better (P < 0.01). Overall, 39 of 44 (89%) patients achieved a satisfactory result. Surgical reconstruction for acromioclavicular dislocation provides reliable results including use of the arm for sports or repetitive work.

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The action of the subscapularis muscle is an important component in maintaining shoulder stability. Because of its relative inaccessibility, there have been few electromyographic (EMG) studies of its normal patterns of activity. The subscapularis is innervated by two or more distinct nerves, and therefore the upper and lower parts of the muscle may have different functional roles depending on the position of the humerus. The purpose of this study was to develop safe, reproducible insertion paths to the upper and lower parts of the subscapularis. Six subjects with no previous history of shoulder injury were evaluated. The paths of insertion were designed based on previous anatomical studies as well as dissections. Two pairs of intramuscular wire electrodes were inserted: one directed toward the upper subscapularis and one toward the lower subscapularis. Electrode locations were confirmed using posteroanterior and lateral radiographs and through electrical stimulation. EMG data were recorded during isometric internal rotation exercises with the humerus in 0 or 90 degrees abduction. Significant differences were observed in the EMG activity recorded from the two pairs of electrodes. The EMG activity of the upper subscapularis either remained the same or decreased in going from 0 to 90 degrees abduction, while that of the lower subscapularis increased. The observed differential response confirmed that the electrodes were in different parts of the subscapularis. These preliminary results suggest that in future EMG studies, the subscapularis should be considered as at least two independent muscle units.

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