Trapezius transfer in brachial plexus palsy. Correlation of the outcome with muscle power and operative technique.

Between March 1994 and June 2003, 80 patients with brachial plexus palsy underwent a trapezius transfer. There were 11 women and 69 men with a mean age of 31 years (18 to 69). Before operation a full evaluation of muscle function in the affected arm was carried out. A completely flail arm was found in 37 patients (46%). Some peripheral function in the elbow and hand was seen in 43 (54%). No patient had full active movement of the elbow in combination with adequate function of the hand. Patients were followed up for a mean of 2.4 years (0.8 to 8). We performed the operations according to Saha's technique, with a modification in the last 22 cases. We demonstrated a difference in the results according to the pre-operative status of the muscles and the operative technique. The transfer resulted in an increase of function in all patients and in 74 (95%) a decrease in multidirectional instability of the shoulder. The mean increase in active abduction was from 6 degrees (0 to 45) to 34 degrees (5 to 90) at the last review. The mean forward flexion increased from 12 degrees (0 to 85) to 30 degrees (5 to 90). Abduction (41 degrees) and especially forward flexion (43 degrees) were greater when some residual function of the pectoralis major remained (n = 32). The best results were achieved in those patients with most pre-operative power of the biceps, coracobrachialis and triceps muscles (n = 7), with a mean of 42 degrees of abduction and 56 degrees of forward flexion. Active abduction (28 degrees) and forward flexion (19 degrees) were much less in completely flail shoulders (n = 34). Comparison of the 19 patients with the Saha technique and the 15 with the modified procedure, all with complete paralysis, showed the latter operation to be superior in improving shoulder stability. In all cases a decrease in instability was achieved and inferior subluxation was abolished. The results after trapezius transfer depend on the pre-operative pattern of paralysis and the operative technique. Better results can be achieved in patients who have some function of the biceps, coracobrachialis, pectoralis major and triceps muscles compared with those who have a complete palsy. A simple modification of the operation ensures a decrease in joint instability and an increase in function.