Anatomical Study of the Contact Area and Degenerative Change of the Proximal Radioulnar Joint During Forearm Rotation

Abstract

Although the articular circumference of the radial head is known to affect lateral stability of the elbow joint, no studies have reported an association between the radial head and radial notch of the ulna, which form the joint. The objective of this study was to investigate, from an anatomical perspective, the association of contact between the radial head and radial notch of the ulna in the proximal radioulnar joint (PRUJ) with development of cartilage injury during pronation and supination of the forearm. Forty-nine elbows from 26 cadavers were included for systemic anatomical study. After the articular circumference of the radial head and the radial notch of the ulna were divided into 4 and 9 regions, respectively, the presence or absence and severity of cartilage injury were determined. The contact area between the radial head and radial notch of the ulna was 50% smaller with the forearm at the pronated position than at the supinated position. Cartilage injury was observed in the medial region of the articular circumference of the radial head and the distal regions of the radial notch of the ulna. These regions corresponded to the contact area of the PRUJ with the elbow joint extended and the forearm pronated. In this condition, the elbow joint becomes most unstable. The elbow joint lateral support complex is likely to be impinged in the humeroradial joint with the elbow joint extended and the forearm pronated, suggesting that repeated impingement might induce cartilage injury.