MORPHOLOGY OF THE ARTICULAR SURFACES OF THE DISTAL RADIOULNAR JOINT

Background: The two articular surfaces of the distal ulna get an impor tant role in load transmission and stabilization of the distal radio-u lnar joint. The present study describes the morphology of the distal r adio-ulnar joint surfaces in terms of the functional relationships bet ween the shape of the ulnar articular facets and the predominant conta ct situation in this joint. Methods: Besides macroscopic dissection an d radiological investigation the model of the ''inclined plane'' has b een used to simulate force transmission across the radio-ulnar joint c oncerning the angle between the distal and the radial articular surfac es of the ulnar head. Results: The presented morphological parameters of the radio-ulnar joint surfaces verify that the transmitted forces a re effective in both a radioulnar and an axial direction. The protecti on and the captaincy of this joint are limited by its great mobility. The investigations show that signs of an increased load pressure are f requently found in the joints that also show degenerative changes, As a morphological sign of the force transmission, distinct spongious tra becles are formed perpendicularly to the articular circumference in th ose ulnar heads that show a stolid angle between their articular facet s. Conclusions: Because of the individuality of the morphological data only qualitative statements can be made both the predominant shapes o f the ulnar head, in particular about the loading of its articular sur faces. The angle between its two articular facets influences the force transmission through the radio-ulnar joint as well as the spongious a rchitecture of the subchondral bone of the ulnar head. (C) 1996 Wiley- Liss, Inc.