- patients with an unstable DRF AO type 23 A2, A3, C1, C2 or C3 elected for surgery with volar plating. Unstable is defined as one of the following: 1) More than 10 degrees dorsal angulation of radius' joint surface in lateral plane measured from an orthogonal axis through radius. 2) Ulnar variance more than 2 mm. 3) Fracture line involving joint surface with more than 2 mm dislocation. 4) Incongruence of the DRJ.