Volar Dislocation of the Distal Ulna in Supination Caused by Apex Volar Malunion of the Radial Shaft: A Report of 2 Cases

INTRODUCTION:Fractures of the distal third of the radius in children are common and most heal without incident. However, distal radial shaft malunion with apex volar angulation may lead to volar dislocation of the distal ulna with forearm supination, although it has been rarely reported. The aim of this study was to document 2 such cases and to make recommendations regarding the management of these patients. METHODS:We report the cases of 2 boys, ages 6 and 8 years, who sustained radial shaft fractures that healed with apex volar angulation and who developed intractable volar dislocation of the distal ulna in adolescence. In both cases, corrective radial osteotomy at the site of the malunion restored full stability of the distal radial-ulnar joint without the need for soft-tissue reconstruction or ulnar styloid nonunion repair. DISCUSSION:This injury pattern is rarely reported but should be considered in cases of repeated volar dislocation of the distal ulna with supination. We recommend a corrective osteotomy at the site of the malunion to restore stability to the distal radial-ulnar joint. LEVEL OF EVIDENCE:IV.