Critical displacement of neural injuries in supracondylar humeral fractures in children.

To investigate a relation between the degree of initial fracture displacement and nerve complication, 53 consecutive acute extension-type supracondylar humeral fractures in children during 10 years were analyzed. From the initial roentgenographs, the direction and degree of displacement of each fracture were plotted on the coronal two-dimensional coordinates at the fracture site. The degree of displacement was represented by a diameter of the humeral shaft. Of 53 fractures, 42 were displaced. Six patients had nerve injuries, representing an 11.3% incidence of neurologic complication. Their displacements were >90% of the diameter of the shaft. Predictive negative and positive displacements of the median nerve were <90% of the diameter and >150% of that in posterolaterally displaced fractures, respectively. Those of radial nerve were <130% and >190% in posteromedially displaced fractures, respectively.