Ulnar Wrist Deviation in Children With Obstetric Brachial Plexus Palsy: A Descriptive Study of Clinical and Radiological Findings of Impaired Ulnar Growth and Associated Incongruence of the Distal Radioulnar Joint.

Backround: Some children with obstetric brachial plexus palsy (OBPP) present later on with an ulnarly deviated wrist. The aim of this study was to present a retrospective analysis of a subgroup of OBPP children with ulnarly deviated wrists and to describe their morphologic wrist deformity in terms of clinical and radiological appearance.
Methods: We present a retrospective analysis of the records of 27 children with an ulnarly deviated wrist as a consequence of OBPP. Radiographs of the affected wrist were performed when the ulnar deformity became clinically manifest and merited investigation, at a mean age of 15 (range: 6.5-27) years. Available clinical and radiological data were analyzed and categorized.
Results: The ulnar-deviated position was associated with impaired active and passive pronosupination in all patients. Fifteen fixed supination deformities and 3 anterior radial head dislocations were noted clinically. Plain radiographs were completed in 24 patients and could be analyzed in 18, showing variations in ulnar variance (7 neutral, 7 ulna minus, and 4 ulna plus) along with 6 subluxations of the distal radioulnar joint (DRUJ). Of the patients treated surgically (n = 7), only the 2 patients treated with wrist fusion had an actual improvement in ulnar wrist deformity.
Conclusion: Radiologically visible ulnar head hypoplasia, overgrowth of the distal ulna, or a shortened ulnar diaphysis and an incongruent DRUJ were present in all examined OBPP patients with a clinically evident ulnarly deviated wrists. The radiological findings highlight the morphologic adaptation behind this clinical condition and could allow further investigation into suitable treatment strategies.