Extremity shortness in obstetric brachial plexus lesion and its relationship to root avulsion.

A total of 73 patients with obstetric brachial plexus palsy and extremity shortness were evaluated clinically, electrophysiologically, and with cervical magnetic resonance imaging. Patients were separated into groups according to age and the level of lesion. The differences of the length of the humerus, ulna, radius, and the second and fifth metacarpal bones were significant between the involved and uninvolved extremities. The difference in shortness increased in relation to the age of the groups and stabilized to approximately 10% in the groups aged 4 to 8 years and 8+ years. A significant relationship was observed between bone length differences and lesion levels. Differences in bone lengths were statistically significant in patients with avulsion in the group aged 8+ years. Extremity shortness appears to be related to avulsion and the level of lesion. The effect of avulsion on extremity shortness gradually increases with age. Finally, root avulsion can be an important factor in extremity shortness of obstetric brachial plexus palsy patients.