Proximal Radioulnar Joint

articulatio radioulnaris proximalis

The proximal radioulnar joint (PRUJ) is the pivot joint at the elbow between the circumference of the radial head and the radial notch of the ulna, stabilised by the annular ligament. It allows forearm rotation (pronation and supination) from the proximal end, while the distal radioulnar joint allows rotation from the distal end. The radial head rotates within the annular ligament ring during forearm rotation.

Region: Forearm

Clinical Relevance

Clinical Notes

Radial head fractures that alter the shape or size of the radial head impair PRUJ mechanics. Essex-Lopresti injuries combine radial head fracture with interosseous membrane disruption and DRUJ instability, producing longitudinal forearm instability. Nursemaid's elbow (pulled elbow) in children is subluxation of the radial head out of the annular ligament from a sudden longitudinal pull on the arm. Monteggia fractures involve the ulnar shaft with PRUJ dislocation; the radial head must always be confirmed reduced in ulnar fracture fixation.

Pathology

Common Injuries & Conditions

Monteggia Fracture Dislocation at PRUJ

Ulnar shaft fracture with proximal radioulnar joint dislocation (Monteggia lesion) requires anatomic ulnar reduction to restore the radial head to the annular ligament; failure to reduce the radial head in an ulnar fracture produces a missed Monteggia with longstanding PRUJ dislocation causing progressive elbow stiffness and radial nerve palsy.