Joints
Distal radio-ulnar joint
The radius turns around the stationary ulna. The articular disc (the TFCC) separates this joint from the wrist joint and carries about 20 per cent of the axial load of the forearm.
- Joint type
- Pivot joint (art. trochoidea), one degree of freedom
- Latin name
- Articulatio radioulnaris distalis
Movements, axes and normal values
| Movement | Plane | Axis | Normal range | End feel |
|---|---|---|---|---|
| Pronation | transverse | longitudinal through the radial and ulnar heads | 0-85 degrees | hard to elastic |
| Supination | transverse | longitudinal through the radial and ulnar heads | 0-90 degrees | elastic |
- Close-packed position
- 5 degrees of supination
- Resting (loose-packed) position
- 10 degrees of supination
- Capsular pattern
- Full range of pronation and supination, but pain at the extreme of both
- Arthrokinematics
- The concave ulnar notch of the radius turns around the convex head of the ulna: roll and glide run in opposite directions. During pronation the radius rolls palmarly and glides dorsally.
- Stability
- The triangular fibrocartilage complex (TFCC), the palmar and dorsal radio-ulnar ligaments, and the interosseous membrane, which transfers load from the radius to the ulna.
- Palpation
- Head of the ulna on the dorsal side of the wrist; have the forearm rotate and it passes under your finger. The fovea between the ulnar head and the flexor carpi ulnaris is the tender point in TFCC injury.
- Clinical
- TFCC injury after a fall onto the outstretched hand or after a distal radius fracture with shortening; ulnar impaction syndrome with a positive ulnar variance.
- Source
- Kapandji, Physiologie articulaire deel 1; Magee, Orthopedic Physical Assessment