Corpus: Proximal radioulnar joint

The proximal radioulnar articulation, or PRUG for short, is a pivot joint, or more precisely a cone joint, which is formed between the proximal ends of the radius and the ulna. The circumferentia articularis radii articulates here with the incisura radialis ulnae and the ligamentum anulare radii, which is cartilaginous on the inner side.

Together with the distal radioulnar articulation (DRUG), the PRUG enables pronation and supination of the forearm. Topographically, the joint is categorised as an elbow joint. As it is a trunnion joint, the circumferentia articularis radii can rotate freely as the joint head in the incisura radialis ulnae, the joint socket. It is stabilised by the ligamentum anulare radii.

PRUG and DRUG form a complex functional unit - comparable to two door hinges - which enables the free positioning of the hand in space. Some authors therefore regard forearm shaft fractures as intra-articular fractures.