Definition

Rheumatoid arthritis is a systemic autoimmune disorder involving the synovial joint lining and is characterized by chronic symmetric erosive synovitis. It has been estimated that 1% to 2% of the world’s population is affected by this disorder. Women are affected more frequently with a ratio of 2.5:1. The cause of rheumatoid arthritis is thought to be multifactorial, including both genetic and environmental factors. The diagnostic criteria for rheumatoid arthritis include symptoms (morning stiffness, symmetric joint swelling, and skin nodules), laboratory test results, and radiographic findings. The wrist is among the most commonly involved peripheral joints; more than 65% of patients have some wrist symptoms within 2 years of diagnosis, increasing to more than 90% by 10 years. Of patients with wrist involvement, 95% have bilateral involvement [1–5].

The inflamed and hypertrophied synovial tissue is responsible for the destruction of adjacent tissues and resultant deformities. The cascade of events that lead to articular cartilage damage is a T cell–mediated autoimmune process mediated by the HLA class II locus [4,5]. The synovium is infiltrated by destructive molecules, resulting in thickening and proliferation of the synovium, chemotactic attraction of polymorphonuclear cells, and release by the polymorphonuclear cells of lysosomal enzymes and free oxygen radicals, which destroy joint cartilage.

The wrist articulation can be divided into three compartments, all of which are lined by synovium and therefore involved in rheumatoid arthritis: the radiocarpal, midcarpal, and distal radioulnar joints. Cartilage loss from both degradation and synovial proliferation contributes to ligamentous laxity of the extrinsic and intrinsic wrist ligaments. The laxity around the wrist leads to the classic rheumatoid deformities of carpal supination and ulnar translocation. The normally stout volar radioscaphocapitate ligament and the dorsal radiotriquetral ligament, which are important stabilizers of the carpus in relation to the distal radius, are stretched, resulting in ulnar translocation of the carpus. Laxity of the volar radioscaphocapitate ligament leads to loss of the ligamentous support to the waist of the scaphoid as well as weakening of the intrinsic scapholunate ligament. The scaphoid responds by adopting a flexed posture, and this is accompanied by radial deviation of the hand at the radiocarpal articulation. The bony carpus supinates and subluxes palmarly and ulnarly; thus, the ulna is left relatively prominent on the dorsal aspect of the wrist, a condition sometimes referred to as the caput ulnae syndrome [5–7]. The secondary effect of carpal supination is subluxation of the extensor carpi ulnaris tendon in a volar direction to the point that it no longer functions effectively as a wrist extensor. The bony architecture of the wrist is affected secondarily, in that the inflammatory cascade also stimulates bone-resorbing osteoclasts, which cause subchondral and periarticular osteopenia.

Areas of the wrist that display vascular penetration into bone or contain significant synovial folds, such as the radial attachment of the radioscaphocapitate ligament (the most radial of the volar radiocarpal ligaments), the waist of the scaphoid, and the base of the ulnar styloid (prestyloid recess), are the most common sites of progressive synovitis. The results of chronic erosive changes in these areas are bone spicules that can abrade and weaken tendons passing in their immediate vicinity, ultimately causing tendon rupture and functional deterioration. The extensor tendons to the small finger and ring finger (Vaughn-Jackson syndrome) [8], which rupture at the level of the ulnar head (see caput ulnae syndrome earlier), and the flexor tendon of the thumb at the level of the scaphoid (Mannerfelt syndrome) [9] are the most commonly involved. In addition to mechanical abrading, the extensor tendons are enclosed in a sheath of synovium at the wrist, which makes them susceptible to the damaging changes of synovial hypertrophy that is commonly seen in rheumatoid arthritis. The synovial proliferation causes changes in tendons of both an ischemic and inflammatory nature, which make them susceptible to weakening and eventual rupture.

Symptoms

Three distinct areas of the wrist can be the source of symptoms from rheumatoid disease: the distal radioulnar joint, the radiocarpal joint, and the extensor tendons. However, symptoms can originate as far proximal as the cervical spine or involve the shoulder and the elbow. Joint-related symptoms in early disease include swelling and pain, with morning stiffness as a classic characteristic. Loss of motion in the early stages usually results from synovial hypertrophy and pain. Progressive loss of motion is seen with disease progression and represents articular destruction. The distal radioulnar joint can be painful because of inflammation within the joint, and it can be a source of decreased forearm rotation (Figs. 41.1 and 41.2). Later stages of the disease usually are manifested with complaints of severe pain, decreased motion, significant cosmetic concerns, and difficulties in performing activities of daily living. Erosive changes are more strongly associated with changes in subjective disability than joint space narrowing is [10].

Tenosynovitis of the tendons traversing the dorsal wrist can often be manifested as a painless swelling. Patients with advanced rheumatoid disease in the wrist or those unresponsive to medical management may present with loss of extension of the digits at the metacarpophalangeal joints or with inability to flex the thumb at the interphalangeal articulation. These findings result from extensor digitorum communis tendon ruptures over the dorsal aspect of the wrist or a rupture of the flexor pollicis longus over the volar scaphoid as described before. Deformity of the wrist and hand is often the most concerning factor for patients and is attributable to the progressive carpal rotation and translocation discussed earlier, coupled with the extensor tendon imbalance accentuated at the metacarpophalangeal joints of the hand, which causes ulnar drift of the digits. The compensatory ulnar deviation occurs at the metacarpophalangeal joints, and it can often be the presenting symptom in undiagnosed or untreated patients.

Symptoms of median nerve compression and dysfunction (altered or absent sensation primarily in the radially sided digits and night pain and paresthesias in the hand) can be associated with rheumatoid arthritis as well. This is primarily due to hypertrophy of the tenosynovium around the flexor tendons within the confined space of the carpal canal, with resulting compression of the median nerve. Vascular damage of the peripheral nerve (rheumatoid neuropathy) may also contribute to symptoms [11].

Physical Examination

Keeping in mind the three primary locations of rheumatoid involvement in the wrist, careful physical examination can help identify the sources of pain and dysfunction and plan a course of treatment. Swelling around the ulnar styloid and loss of wrist extension secondary to extensor carpi ulnaris subluxation indicate early wrist involvement. Dorsal wrist swelling is commonly present and can be due to radiocarpal synovitis, tenosynovitis, or a combination of the two processes. An inflamed synovial membrane surrounding the radiocarpal joint is usually tender to palpation, but there can be surprisingly little swelling on examination if it is confined only to the dorsal capsule. Swelling that is related to the joint usually does not display movement with passive motion of the digits. Tenosynovitis, however, is typically painless and nontender and moves with tendon excursion as the digits are moved.

Distal radioulnar joint involvement is confirmed with tenderness to palpation, pain, crepitation, limitation of forearm rotation, and prominence of the ulnar head indicating subluxation or dislocation. If the ulnar border of the hand and carpus are in straight alignment with the ulna, it is indicative of radial deviation and carpal supination. As mentioned previously, ulnar drift of the digits at the metacarpophalangeal joints often accompanies this. It is important to examine the function and integrity of the tendons of the digits, primarily the extensor tendons and flexor pollicis longus tendon, to identify any attritional ruptures that may be present.

Examination for provocative signs of carpal tunnel syndrome includes eliciting of Tinel sign over the carpal canal, reproduction or worsening of numbness in the digits with compression over the proximal edge of the canal at the distal wrist crease (Durkan test), and flexion of the wrist (Phalen test). A careful neurologic examination may detect decreased light touch sensibility in the thumb, index, middle, and radial aspects of the ring finger if there is advanced median nerve dysfunction. Consideration should be given to the possibility of more proximal (cervical neuropathy) causes of symptoms.

If there is significant synovitis of the radiocapitellar joint proximally, there can be posterior interosseous nerve dysfunction as well. This is manifested during the wrist and hand examination as the inability to extend the thumb and digits and, to some extent, the wrist. This finding, however, needs to be differentiated from tendon rupture or subluxation at the level of the metacarpophalangeal joints. Strength testing may be diminished because of pain from synovitis, muscle atrophy, or the inability to contract a muscle secondary to tendon rupture.

Functional Limitations

Rheumatoid patients often have shoulder, elbow, and hand involvement and an abnormal wrist, which leads to significant limitations in activities of daily living. Because the distal radioulnar joint is important in allowing functional forearm rotation and in helping to position the hand in space, advanced synovitis of this joint causing pain and fixed deformity can have a severe impact on a patient’s daily functional activity. Functional difficulties that are commonly experienced by these patients include activities of lifting, carrying, and sustained or repetitive grasp. Whereas a loss of pronation may be compensated for by shoulder abduction and internal rotation, supination loss is very difficult to compensate. This can lead to difficulty in opening doors and turning keys. Simple acts such as receiving change during shopping can be compromised by reduced supination. Furthermore, in patients with shoulder involvement, the freedom of compensatory motion at the shoulder can be severely limited, compounding the limitations imposed on the patient’s function by limitation of forearm rotation.

Diagnostic Studies