Upright MRI of glenohumeral dysplasia following obstetric brachial plexus injury.

The purpose of this study was to evaluate the role of upright magnetic resonance imaging (MRI) shoulder scanning in the diagnosis of glenohumeral deformity following obstetric brachial plexus injury (OBPI). Eighty-nine children (ages 0.4 to 17.9 years) with OBPI who have medial rotation contracture and reduced passive and active lateral rotation of the shoulder were evaluated via upright MRI of the affected glenohumeral joint. Qualitative impressions of glenoid form were recorded, and quantitative measurements were made of glenoid version and posterior subluxation. Glenoid version of the affected shoulder averaged -16.8 +/- 11.0 degrees (range, -55 degrees to 1 degrees ), and percentage of the humeral head anterior to the glenoid fossa (PHHA) averaged 32.6 +/- 16.5% (range, -17.8% to 52.4%). The glenoid form was normal in 43 children, convex in 19 children and biconcave in 27 children. Standard MRI protocols were used to obtain bilateral images from 14 of these patients. Among the patients with bilateral MR images, glenoid version and PHHA were significantly different between the involved and uninvolved shoulders (P<.000). Glenoid version in the involved shoulder averaged -19.0 +/- 13.1 degrees (range, -52 degrees to -3 degrees ), and PHHA averaged 29.7 +/- 18.4% (range, -16.2% to 48.7%). In the uninvolved shoulder, the average glenoid version and PHHA were -5.2 +/- 3.7 degrees (range, -12 degrees to -1 degrees ) and 47.7 +/- 3.0% (range, 43% to 54%), respectively. The relative beneficial aspects of upright MRI include lack of need for sedation, low claustrophobic potential and, most important, natural, gravity-influenced position, enabling the surgeon to visualize the true preoperative picture of the shoulder. It is an effective tool for demonstrating glenohumeral abnormalities resulting from brachial plexus injury worthy of surgical exploration.