The ulnar head is semicylindrical, with a radius of curvature of 10 mm, and has an articulate convexity of 220 degrees. It is surrounded by the ulnolunate and ulnotriquetral ligaments, which originate from the palmar radioulnar ligament near the ulnar styloid.

The TFC is a fibrocartilaginous disc originating at the junction of the lunate fossa and the sigmoid notch inserting at the base of the ulnar styloid. Its central portion is cartilaginous and avascular and is designed for weight bearing.

The peripheral margins, the dorsal and palmar radioulnar ligaments, are thick lamellar cartilage designed for tensile loading. They are well vascularized from the palmar and dorsal branches of the anterior interosseous artery and from the ulnar artery.

The ulnar styloid acts as a strut on the end of the ulna to stabilize the ulnar soft tissues of the wrist. The sheath of the extensor carpi ulnaris (ECU), the ulnocarpal ligaments, and the TFC attach at the base of the ulnar styloid to the fovea and together are known as the triangular fibrocartilage complex (TFCC).

The stability of the DRUJ comes from the joint surface morphology, the joint capsule, the dorsal and palmar radioulnar ligaments, the interosseous membrane (particularly the distal oblique bundle), and the musculotendinous units that cross the joint, primarily the ECU and pronator quadratus. The pronator quadratus actively stabilizes the joint by coapting the ulnar head in the sigmoid notch in pronation and passively by viscoelastic forces in supination. The ECU is retained over the dorsal distal ulna by a separate fibro-osseous tunnel deep to and separate from the extensor retinaculum, allowing unrestricted rotation of the radius and ulna.¹⁸

Wrist weakness with pain on pronation and supination

Dorsal prominence of the ulnar head

Limitation of pronation and supination

Swelling of the distal radioulnar area

Secondary tendon changes with possible extensor tendon rupture and ECU subluxation¹

If allowed to progress without intervention, the carpus will eventually fall in a more ulnarward and palmarward direction, with strength, mobility, and function all suffering.²¹

As a group, many of these reconstructions fail to restore stability; even if stability is restored, limitation of forearm motion persists.

When positive ulnar variance exceeds a few millimeters, additional limitations of wrist flexion-extension as well as radial-ulnar deviation movements can occur.

A history of fracture involving the forearm or wrist is clearly important. Patients may recall a specific injury involving damaging forces of torque with axial load applied to the involved wrist and forearm. In the absence of trauma, congenital conditions may also be considered.

The patient’s occupation or hobbies may give insight into the mechanism of injury as well as the most important functional deficits currently experienced by the patient.

A complete medical history is important, including questions about inflammatory arthritis or osteoarthritis.

Pain is exacerbated with activity and increases with resisted rotation of the forearm.

With large ulnar length discrepancy (positive ulnar variance), limited flexion-extension also can be seen.

The clinician should check for instability or chronic dislocation of the joint, comparing the injured with the uninjured wrist.

The patient’s normal and affected wrist and forearm ranges of motion, both active and passive, should be measured. A rigid end point with loss of motion suggests bony pathology such as fracture malunion, whereas a soft end point with limited motion suggests soft tissue contractures.

The clinician should carefully palpate, ballote, and compress around the DRUJ and compare the findings to the opposite side. Grip strength measurements should be checked bilaterally. The presence of isolated pain on palpation of the fovea should lead the examiner to consider other etiologies such as a TFCC tear or split ulnotriquetral ligament tear.

When evaluating patients with RA, the clinician should try to distinguish the pain and instability of the DRUJ from radiocarpal and midcarpal joint symptoms by careful palpation, ballottement, and compression of areas around the DRUJ, comparing the degree of symptoms elicited by forearm rotation versus wrist flexion-extension.

Piano key test. The test, which isolates DRUJ disorders, is positive if it causes pain and/or crepitus.

Selective anesthetic injections. The test is positive when precise, selective injection of anesthetic into the area eliminates pain and improves function. Injections help to confirm pathologic changes and can be used to distinguish intra-articular from extra-articular lesions.

Ulnocarpal compression test. A positive test reproduces the ulnar-sided wrist pain and grinding by translating force across the TFC. It also isolates pathologic changes in the TFC.

Lunotriquetral (Regan) shuck test. Pain, sometimes with increased joint mobility and grinding, represents a positive test. This test detects and assesses abnormalities or pathologic conditions associated with the lunotriquetral joint.

Tendinitis should be treated first with stretching exercises, other physical therapy modalities, and sometimes a steroid injection before addressing the DRUJ surgically.

Commonly, resection of the distal end of the ulna, the Darrach procedure, is recommended for patients with RA and ulnar-sided wrist pain. However, the inflammatory changes and deforming forces acting on the hand and wrist in RA tend to cause palmar and ulnar translocation of the wrist and secondary radioulnar impingement resulting in decreased mobility, strength, and function. Removal of the distal ulna exacerbates and accelerates the problem.

With the Sauvé-Kapandji procedure, the retained distal ulna provides bony support for the ulnar corner of the wrist to help stabilize against the palmar-ulnar slide of the carpus (FIG 1). In addition, the important attachments of the ulnocarpal complex are preserved.²¹

In cases of wrist trauma with ulnar-sided ligamentous injury and incompetence, retaining the ulnar head, as is performed with a Sauvé-Kapandji reconstruction, maintains the ulnocarpal buttress and the TFC to allow a more physiologic transmission of load from the hand to the forearm.

The osteotomy made in the ulna in the Sauvé-Kapandji procedure allows as much shortening as is needed to match the level of the radius while retaining supination and pronation.