Classification of impairment of shoulder abduction in obstetric brachial plexus palsy and its clinical significance.

Shoulder abduction was studied in 25 cases of obstetric brachial plexus palsy (OBPP). According to muscle function, electromyographic features and X-ray examination, impairment of shoulder abduction could be classified into dynamic, resistant or combined types. Five cases were the dynamic type, which was characterized by paralysis of the shoulder abductors. Fifteen cases were categorized as the resistant type, with contracture of the subscapularis muscle, co-contraction of latissimus dorsi and teres major muscles and secondary disorders of the shoulder joint. Five cases were classified as the combined type in which there were both dynamic and resistant factors. Appropriate management and surgical procedures in the shoulder affected by OBPP depend on the pathological classification.