Measuring secondary deformities of the shoulder in children with obstetric brachial plexus lesion: reliability of three methods.

In this study the interobserver reliability of three established measurement methods to objectify secondary deformities of the shoulder in obstetric brachial plexus lesion was evaluated (OBPL). Magnet resonance imaging scans of 30 affected shoulders of 29 OBPL children, mean age 1 year 9 months (range 3 months to 6.3 years) were used. The reliability of the measurement of glenoid version had a standard deviation of differences of measurements between 5.4 and 5.9 degrees. The reliability of the glenoid form showed a kappa value between 0.52 and 0.64, and the reliability of the humeral subluxation had a standard deviation between 7.7 and 12.4 degrees. The measurement methods showed no systematic bias.