This document discusses the distal radioulnar joint (DRUJ). It notes that the DRUJ is primarily stabilized by soft tissues like the triangular fibrocartilage complex (TFCC) which provide around 80% of stability, while the bony articulation between the radius and ulna provides the remaining 20%. The document describes the anatomy of the DRUJ including the sigmoid notch of the radius, ulnar head, and ligaments. It notes that the ulna remains fixed while the radius rotates around it during pronation and supination. Assessment of the DRUJ includes measuring the normal arc of rotation and observing how the ulnar head slides during motion.

1. Wrist
Distal Radioulnar Joint
Dr/Mohamed Mattar
MBBH,Msc,MD
Lecturer of Radiology
Al-Azhar University

2. Wrist
Distal Radioulnar
Joint
DR/MOHAMED MATTAR
MBBH,MSC,MD
ALAZHAR UNIVERSITY HOSPITAL

3. DRUJ Stability
 Bony articulation
- sigmoid notch of radius
about 20% of the overall stability.
 soft tissues
- TFCC and others about 80% of stability

4. Bony anatomy of DRUJ
- It is a pivot joint
Sigmoid notch
 Allows radius to rotate at the convex surface of ulna which remains fixed.
Ulnar head
 Slide dorsally in pronatation and vollary in supination.
DRUJ
 8-9 mm of dorsal palmar translate when external force applied.

5. Sigmoid notch
variants
 Flat face about 40%
more liable to instability
 Ski-slope.
 C type
 S type

6. Ligamentous anatomy (volar aspect)
 Primary stabilizer
 TFC disc proper
 Volar radioulnar ligament
 Meniscal homologue
 UCL
 Extrinsic ligaments
 Volar UT and UL.
 UCL.

7. Ligamentous
anatomy(dors
al aspect)
Primary stabilizer
 TFC disc proper
 Volar radioulnar
ligament
 UCL
 ECU tendon sheath
 Meniscal homologue

8. Biomechanics
 Misnormer ulna rotates
around the distal radius.
 Ulna remains fixed.
 Distal radius rotates around it.
 Supination shortens the ulna
to radius.
 Pronation lengthens ulna to
radius

9. Assessment of DRUJ
Normal arc of rotation
 Ranges form 150 to 180 degree.
Ulnar head slides
 Supination: volary
 Pronation : dorsally
Ligaments
 Volar deep fibres of radioulnar
ligament prevent translation during
pronation
 Dorsal deep fibers prevent translation
during supination

10. Assessment of stability on CT.
 Mino method