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Distal Radioulnar Joint

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The wrist is an anatomic linkage bridging the hand to the forearm. Eight bones of carpus and the distal radius and ulna form complex articulation that allow 3 degrees of movement. The hand, relative to the forearm, can flex and extend, pronate and supinate, and deviate ulnar and radial. [17]
In order to have such mobility while maintaining stability, the wrist has complex configuration of ligaments and bones. Malfunction of the wrist occurs when the structural alignment of the bones has changed or when the ligamentous constraints have been disrupted. [17]

The distal radioulnar joint (DRUJ)
Problems of the DRUJ have been called by Palmer as the “low back pain of the wrist. [18]

Over the last years, there has been a tremendous surge in research involving the anatomy, function, and treatment of DRUJ pathology.
In the DRUJ: The shallow concave sigmoid notch of the distal radius articulates with the convex asymmetric shaped ulnar head.
The …show more content…

1 : Types of sigmoid notch. [ 21]
There is also reported a palmar osteocartilagenous lip in 80% of the people which acted as a stable buttress to palmar dislocation of the ulna.
The articulation of the sigmoid notch with the ulnar head allows rotation of the radiocarpal unit in the transverse plane.[ 19]
The ulna head:
The medial area of it has a bony prominence, whichis known as the ulnar styloid process. This is the point of attachment for soft tissue structures. The dorsal nonarticular portion of the ulnar head has an osseous groove to accommodate the extensor carpi ulnaris tendon (ECU). Articular cartilage covers a 90 to 135 degrees arc of the ulnar head, and only a 47 to 80 degree arc on the sigmoid notch.[20]
One important geometric joint characteristic of the DRUJ is the radius of curvature between the two articulating surfaces. The radius of curvature of the ulnar head (averages 10 mm) is different from the radius of curvature of the sigmoid notch (averages 15 mm). Consequently,

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