Modified osteotomy (Kanaya's procedure) for congenital proximal radioulnar synostosis with posterior dislocation of radial head.

Outcomes of Kanaya's procedure for congenital proximal radioulnar synostosis varied depending on the type of radial head dislocation. In our series of 14 patients with 17 forearms who underwent Kanaya's original procedure, the postoperative total rotation arc of the forearm was unsatisfactory in cases with posterior radial head dislocation. We examined the outcomes with respect to the type of radial head dislocation and radial shaft curvature. Radial shafts with a posterior radial head dislocation had only one curve and the radii of the curve were statistically smaller than those in anterior dislocated or enlocated heads, which had two curves. As a result, we modified the osteotomy site for proximal radioulnar synostosis with posterior radial head dislocation and achieved improved forearm rotation and physiological rotation of the radial head in our latest two cases.