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Home › Body Atlas › Joints › Superior Radioulnar Joint (Detail)
Joint Upper Arm

Superior Radioulnar Joint (Detail)

articulatio radioulnaris proximalis (detail)

The proximal radioulnar joint is the proximal pivot of forearm rotation, where the radial head rotates within the socket of the radial notch and annular ligament. The radial head is elliptical in cross-section. During forearm rotation it must accommodate this elliptical geometry, which is why a malunited radial head fracture (changing the ellipse) restricts rotation before articular surface incongruence. The PRUJ is also the site of radiocapitellar impingement in lateral elbow overuse.

An expanded entry for Superior Radioulnar Joint.

Anatomical Data

Structure

Bones
Ligaments
  • Annular ligament (primary PRUJ stabiliser)
  • LCL complex (LUCL, lateral stabiliser)
  • Interosseous membrane (longitudinal link)
Biomechanics

Function & Actions

Movements
  • Forearm pronation-supination at the proximal pivot
  • The radial head is an ellipse. Full rotation requires the annular ligament to accommodate the elliptical cross-section
Clinical Relevance

Clinical Notes

Radial head fractures are the most common elbow fractures in adults. Mason classification: Type I (non-displaced, treat non-operatively), Type II (partial, may require ORIF if mechanical block), Type III (comminuted, ORIF or radial head replacement), Type IV (with elbow dislocation). Radial head excision alone is contraindicated if the PRUJ is the only proximal ulna support (Essex-Lopresti).

Pathology

Common Injuries & Conditions

Radial Head Fracture

PRUJ injury from FOOSH classified by Mason system, non-operative for Type I, ORIF or arthroplasty for Type III-IV.

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