The radioulnar ligaments extend from the palmar and dorsal distal margins of the sigmoid notch and converge in a triangular configuration to attach to the ulna as the principal stabilizers of the DRUJ ( The primary functions of the TFCC are to extend the articular surface of the distal radius to the ulnar head, transmit axial force across the ulnocarpal joint, provide a strong but flexible connection between the distal radius and ulna, and support the ulnar portion of the carpus. The TFCC is formed by the triangular fibrocartilage proper, ulnocarpal meniscal homologue, the ulnar collateral ligament, the superficial and deep dorsal and volar radioulnar ligaments, and the sheath of the ECU. These soft tissue restraints include the triangular fibrocartilage complex (TFCC), joint capsule, interosseus membrane (IOM), and musculotendinous units consisting of the extensor carpi ulnaris (ECU) and pronator quadratus. The remainder of the stability is afforded by the surrounding soft tissue. Based on an anatomic study of 50 cadavers, Tolat et al observed four different sigmoid notch shapes: flat face (42%), ski slope (14%), “C” type (30%), and “S” type (14%).Ī flat sigmoid notch may be more prone to instability and less responsive to treatment by soft tissue repair alone.īony architecture only accounts for approximately 20% of the DRUJ’s stability. The shape of the sigmoid notch has important implications with respect to traumatic instability ( At the extremes of pronation and supination, there may be only 2 mm of articular contact at the rims of the notch that correspond at less than 10% of the articular surface area of the joint. However, these forces can vary with ulnar and radial deviation. In a normal wrist, the majority of the force at the wrist is transmitted through the radius (80%), with only 20% of the load transmitted through the ulna. DRUJ motion is primarily rotational with components of axial and translational motion. The normal total arc of motion at the DRUJ is 150 to 180 degrees, with an additional 30 degrees through the radiocarpal joint. It provides a pivot for pronation–supination of the distal forearm. The DRUJ is an incongruent diarthrodial, synovial articulation between the distal radius and ulna ( Lastly, we will discuss the various treatment options available to maximize patient outcomes. We review relevant anatomy and biomechanics, common signs and symptoms in the evaluation, and diagnostic protocols including a discussion of relevant upper extremity fractures that should raise the clinicians’ index of suspicion of DRUJ injury. The objective of this article is to review the literature on DRUJ instability and explore injuries of the upper extremity that are associated with DRUJ injury. Thus, DRUJ injury warrants a thorough clinical examination and when necessary, directed treatment modalities. However, chronic instability can be a source of morbidity in patients, leading to pain, dysfunction, and arthritis. The role of DRUJ instability in determining long-term functional outcomes in upper extremity injuries is still debated. As DRUJ instability is often secondary to other injuries, it can go unnoticed on initial presentation. Distal radioulnar joint (DRUJ) instability is a potential sequalae of fracture/dislocations of the upper extremity and can also present in isolation.
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