This is a prospective study of 107 repairs of obstetric brachial plexus palsy carried out between January 1990 and December 1999. The results in 100 children are presented. In partial lesions operation was advised when paralysis of abduction of the shoulder and of flexion of the elbow persisted after the age of three months and neurophysiological investigations predicted a poor prognosis. Operation was carried out earlier at about two months in complete lesions showing no sign of clinical recovery and with unfavourable neurophysiological investigations.

Twelve children presented at the age of 12 months or more; in three more repair was undertaken after earlier unsuccessful neurolysis. The median age at operation was four months, the mean seven months and a total of 237 spinal nerves were repaired.

The mean duration of follow-up after operation was 85 months (30 to 152). Good results were obtained in 33% of repairs of C5, in 55% of C6, in 24% of C7 and in 57% of operations on C8 and T1. No statistical difference was seen between a repair of C5 by graft or nerve transfer.

Posterior dislocation of the shoulder was observed in 30 cases. All were successfully relocated after the age of one year. In these children the results of repairs of C5 were reduced by a mean of 0.8 on the Gilbert score and 1.6 on the Mallett score. Pre-operative electrodiagnosis is a reliable indicator of the depth of the lesion and of the outcome after repair. Intra-operative somatosensory evoked potentials were helpful in the detection of occult intradural (pre-ganglionic) injury.