This is a prospective study of infants less than 1 year of age with obstetrical brachial plexus palsy. MRI’s were obtained to assess the configuration of the bone and cartilage in the shoulder. Sixteen consecutive infants who were under consideration for neurosurgical reconstruction underwent MRI evaluation of both shoulders. One child had bilateral brachial plexus injuries, for a total of 17 affected shoulders. Abnormalities were observed in 10 of the 17 shoulders studied. Seven glenoids were convex and 3 biconcave. Subluxation of the humeral head was greater on the affected side, although glenoid version was the same as the unaffected side. Age was an apparent predictor of glenohumeral dysplasia. In children less than 5 months of age, a normal appearing glenoid was found in 5 of 7 shoulders. In older infants, the appearance of the glenoid was normal in only 2 of 10.
Children with residual obstetrical brachial plexus palsy often have internal rotation contractures of the shoulder. This is believed to contribute to abnormal development between the glenoid and the humeral head. This study indicates that shoulder joint abnormalities may occur at an even younger age. The etiology may still be from deficient external rotation, which does not allow the glenoid physis to develop normally. The study is somewhat biased in selecting only children with persistent neurologic deficits who were considered candidates for surgical intervention. However, it does lend further support for early intervention with children affected with brachial plexus palsy. Shoulder reconstruction and tendon transfers may be required to augment external rotation and encourage normal development of the glenohumeral joint.