An Original Prosthesis of the Distal Radioulnar Joint

Abstract

Pronation-supination is one of the most important motions of the upper limb, indispensable to the orientation of the hand. It is often problematic, particularly in distal radioulnar joint (DRUJ) dislocations after Colles fracture and in other circumstances, isolated ulnar fractures, two-bone fractures, Galeazzi fractures, and also in rheumatoid arthritis. Many procedures are proposed for the treatment of pronation-supination troubles or traumatic painful instabilities of the DRUJ but in all these procedures except that by Milch, the risk of painful instability of the ulnar stump is real, such as after a Kapandji-Sauvé or a Moore-Darrach operation. When this occurs, ulnar stump stabilization is very difficult to obtain. Liga-mentQplasties have been proposed but their results are hazardous. Then the idea of a mechanical fixation by mean of a DRUJ prosthesis emerged. After considering the characteristics of this joint, it appears that a “ball and socket” joint prothesis is convenient with little losseness. The original principles of the DRUJ prothesis are: cementless fixation but with screws, composition of the articular pieces and a metal spherical head fitting with an HD polythylene cup. The articular surfaces are supported by two pieces: the proximal part, set on the ulnar stump, bearing a hollow hemisphere, coated with an HD polyethylene cup and fixed with a transversal screw on an intra-medullary stem; and the distal part, holding a sphere, the ball, fitting with the cup and fixed on the radius lower extremity by two special screws. Two models with the same proximal part were designed depending on whether or not the ulnar head was to be saved. The indication of this DRUJ prothesis is painful instability of the ulnar

stump when the ulnar resection is too large, after a Kapandji-Sauvé procedure or after a Moore-Darrach procedure. The DRUJ arthroplasty technique is also described, that needs a few additional ancillary tools. Until now, these protheses have been used in 2 cases, with or without a saved ulnar head. The results seem to have been favourable, with a total range of pronation-supination, stability, and painlessness. Obviously, it is too early to know their final value; we know that with clinical experience, the techniques will evolve, mainly the in fixation system. However, it seems important to make it known as an additional possibility in the treatment of DRUJ problems.