Clinical and non-clinical aspects of distal radioulnar joint instability

Abstract

Untreated distal radioulnar joint (DRUJ) injuries can give rise to long lasting complaints. Although common, diagnosis and treatment of DRUJ injuries remains a challenge. The articulating anatomy of the distal radius and ulna, among others, enables an extensive range of forearm pronosupination movements. Stabilization of this joint is provided by both intrinsic and extrinsic stabilizers and the joint capsule. These structures transmit the load and prevent the DRUJ from luxation during movement. Several clinical tests have been suggested to determine static or dynamic DRUJ stability, but their predictive value is unclear. Radiologic evaluation of DRUJ instability begins with conventional radiographs in anterioposterior and true lateral view. If not conclusive, CT-scan seems to be the best additional modality to evaluate the osseous structures. MRI has proven to be more sensitive and specific for TFCC tears, potentially causing DRUJ instability. DRUJ instability may remain asymptomatic. Symptomatic DRUJ injuries treatment can be conservative or operative. Operative treatment should consist of restoration of osseous and ligamenteous anatomy. If not successful, salvage procedures can be performed to regain stability.

Keywords: DRU-joint; Distal radioulnar joint; instability; wrist..

Fig. (1a)

The distal radioulnar articulation is formed by the distal sides of the radius and the ulna, the sigmoid notch and ulnar seat (A) respectively. The inclination of the radius (striped line) differs from the ulnar inclination. S = scaphoid bone, L = lunate bone, T = triquetral bone.

Fig. (1b)

The ulnar seat has a smaller radius (small circle) compared to the sigmoid notch (large circle).

Fig. (2)

The main extracapsular stabilizers of the DRU joint with one of the three reinforced areas of the interosseous membrane.

Fig. (3)

The triangular fibrocartilage complex. The disc (not drawn in this figure) is stretched between ulna and radius proximally and lunate and triquetral bones distally. The two ulno-carpal ligaments are the ligaments that are partially resected in this figure.

Fig. (4)

The dorsal and palmar radioulnar fibers originate from the medial border of the distal radius and insert on the ulna at two distinct sites; deep fibers at the ulnar fovea and superficial fibers at the ulnar styloid.

Fig. (5)

When load is applied to the hand (F) with a specific moment ( L), the fixed fulcrum (E) is the DRUJ. Stability is defined as equality in forces, with their specific moments, working on a fixed fulcrum. If the elbow is stable, the load between elbow and DRUJ (F’ x L’) will equal the load between the DRUJ and the hand (F x L) in a stable situation.

Fig. (6a)

When the radius rotates around the ulna in pronation, the dorsal superficial fibers tighten, as do the deep palmar fibers.

Fig. (6b)

When the radius rotates around the ulna in supination, the palmar superficial radioulnar fibers tighten, as do the deep dorsal fibers.

Fig. (7)

The stress-test is performed by provoking anterolateral movement of the radius, while stabilizing the ulna. By comparing the stability of both the injured with the non-injured wrist, DRUJ instability can be diagnosed.