[Distal radio-ulnar joint. Traumatic and degenerative diseases]

The distal radio-ulnar joint participates in the biomechanics of the wrist both by transmission of carpal stresses and by its role in the mobility of the wrist. Fractures of the distal radio-ulnar joint are often missed as they are frequently only a radiation of fractures of the radius to the distal radio-ulnar joint. Computed tomography is the most useful examination to assess the severity of these lesions. Distal radio-ulnar dislocations may also be associated with fractures of the radius, but usually occur in isolation. The diagnosis is difficult, as the slightest rotation on plain X-rays interferes with the evaluation criteria. A CT scan in the neutral position and in pronation and supination is the examination of choice for dislocations and subluxations, but must be interpreted according to strict criteria. In contrast, a tea of the triangular ligament can only be assessed on arthrography and the distinction between traumatic and degenerative rupture is difficult. The patient's age, the site of the perforation and the length of the ulna are important elements in the diagnostic decision. MRI appears to be a promising examination for investigation of this joint, but the quality of the images is not yet perfectly reproducible.