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Home › Body Atlas › Joints › Inferior Radioulnar Joint (Detail)
Joint Forearm

Inferior Radioulnar Joint (Detail)

articulatio radioulnaris distalis (detail)

The DRUJ is the distal pivot of forearm rotation where the sigmoid notch of the radius rotates around the ulnar head. The TFCC fills the gap distal to the ulnar head, transmitting 20% of axial wrist load. DRUJ instability from distal radius malunion, TFCC tears, or Essex-Lopresti injury produces painful forearm rotation. Ulnar positive variance (ulnar head protruding beyond the radial articular surface) increases TFCC compressive loading and produces ulnar abutment syndrome.

Anatomical Data

Structure

Bones
Ligaments
  • TFCC deep fibres (primary DRUJ stabilisers)
  • Dorsal and palmar radioulnar ligaments
  • Interosseous membrane distal oblique bundle
Biomechanics

Function & Actions

Movements
  • The radius rotates around the ulnar head during pronation (80 degrees) and supination (80-90 degrees)
  • The ulnar head translates 2-3 mm during rotation, dorsal in supination, palmar in pronation
Clinical Relevance

Clinical Notes

Ulnar positive variance greater than 2 mm produces TFCC central perforation, lunate chondromalacia, and lunotriquetral ligament tears from repetitive impaction (ulnar abutment syndrome). Ulnar shortening osteotomy (removing 2-4 mm of ulnar length) reliably reduces impaction load and resolves symptoms in 85-90% of cases.

Pathology

Common Injuries & Conditions

Ulnar Abutment Syndrome

Positive ulnar variance producing TFCC and lunate chondral injury managed with ulnar shortening osteotomy.

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