[Replacement and resurfacing prosthesis of the distal radius: a new therapeutic concept].

Complex intra-articular distal radius fractures represent a challenging therapeutic problem. We propose in these difficult cases to replace and to resurface the distal radius by a prosthesis, especially in fractures related to aging and osteoporosis. We have designed an anatomic prosthesis to replace and resurface the distal radius. The design was obtained from radiographs, tomograms and anatomical specimens. The prosthesis is composed of a radial stem and an epiphyseal-metaphyseal bloc articulating both with the carpal condyle and the ulnar head. The epiphyseal-metaphyseal bloc can rotate 10 degrees on the longitudinal axis of the stem. From March 2005 to February 2007, six patients were operated on: five women and one man, the mean age was 73 years (38-87). Five cases were elderly and osteoporotic patients: four had complex intra-articular fractures and one had a malunion complicated by extensor tendon ruptures. In one case, the procedure was performed on a young man with a pathologic fracture (giant cell tumor). The patients were reviewed with a mean follow-up of 27 months (13-36 months). Five patients are satisfied or very satisfied but one patient is dissatisfied due to a stiff wrist after an algodystrophic syndrome. The mean mobilities are: extension 65 degrees, flexion 30 degrees, ulnar inclination 20 degrees, radial inclination 20 degrees, pronation 60 degrees, supination 50 degrees. The mean strength was 80% of the contralateral side. The implants are perfectly stable on the radiographs. Replacement and resurfacing of the distal radius by a prosthesis articulating both with the carpal condyle and ulnar head is possible. The preliminary clinical results are good. This prosthesis takes into account the transmission of the pronosupinator couples through the wrist. The longitudinal rotation between the stem and the epiphyseal-metaphyseal bloc has three goals: the first is to decrease the constraints born from the pronosupination torques, the second is to improve the congruence with the carpal condyle, the third is to increase radio-ulnocarpal stability. The treatment of complex intra-articular distal radius fractures by replacement and resurfacing prosthesis is a solution we can now consider in elderly patients with osteoporosis. This solution seems ideal for distal radius tumors.