GLENOHUMERAL DEFORMITY SECONDARY TO BRACHIAL-PLEXUS BIRTH PALSY

Ninety-four patients who had brachial plexus birth palsy were entered into a prospective study to evaluate the association between persisten t palsy, age-related musculoskeletal deformity, and functional limitat ions. Of these patients, forty-two had either computerized tomography or magnetic resonance imaging to assess the presence and degree of inc ongruity of the glenohumeral joint, deformity of the humeral head, and hypoplasia of the glenoid as part of the preoperative planning for a reconstructive operation. Functional ability was rated with use of the classification of Mallet, on a scale of 1 to 5. The mean glenoscapula r angle (the degree of retroversion of the glenoid) on the affected si de was -25.7 degrees compared with -5.5 degrees on the unaffected side . Twenty-six (62 per cent) of the forty-two shoulders had evidence of posterior subluxation of the humeral head, with a mean of only 25 per cent (range, 0 to 50 per cent) of the head being intersected by the sc apular line. Progressive deformity was found with increasing age (p < 0,001). The natural history of untreated brachial plexus birth palsy w ith residual weakness is progressive glenohumeral deformity due to per sistent muscle imbalance. The status of the glenohumeral joint must be addressed when the choice between tendon transfer and humeral derotat ion osteotomy for reconstruction of the shoulder is considered for the se patients.