Glenoid version in children with obstetric brachial plexus palsy.

Glenoid version in a group of 29 children with obstetric brachial plexus paralysis and posterior dislocation of the shoulder was studied by using computed axial tomography (CT). The CT scan in most patients was done before an open release and reduction of the shoulder. A comparison was made between the normal and affected sides in regard to glenoid version and structure. In the study population, there were 16 girls and 13 boys with an average age at the time of initial CT of 2.8 years. Sixteen of the patients had posterior dislocations of the right shoulder, and none was bilateral. In 18 patients, the neurologic lesion was confined to the upper roots of the brachial plexus, with the remaining patients having whole plexus involvement. A significant difference in glenoid version between normal and affected sides was found in these patients. The mean glenoid version for the dislocated side was -29.5 +/- 2.5 degrees and that of the normal side was -6.9 +/- 2.4 degrees. Glenoid structure was different in dislocated shoulders. The glenoid articular surface was observed to be laterally convex in the majority of cases, and in these cases, the posterior rim of the glenoid was often hypoplastic and rounded.