The first and most important step in evaluating a patient with polyarticular joint pain is determining whether or not synovitis/arthritis is present, producing soft tissue swelling, joint effusion, tenderness, warmth of the joint, and limitation of both active and passive range of motion. If the only finding is pain without inflammatory changes, then the diagnostic considerations include noninflammatory diseases such as osteoarthritis (OA), fibromyalgia, hypothyroidism. neuropathic pain, and depression. The presence of soft tissue swelling and tenderness with limited active range of motion but normal passive range of motion suggests the problem is extraarticular soft tissue inflammation, such as bursitis or tendonitis.
If there is active synovitis/arthritis. it is clinically useful to distinguish between monoarticular/oligoarticular arthritis (see Chapter 21) and polyarticular arthritis. In polyarticular disease, the next diagnostic clue is the duration of symptoms. If symptoms are relatively acute (<6 weeks), the major considerations are arthritis due to viral infection (such as hepatitis B or C, rubella, or parvovirus B19) or the earliest manifestation of a true rheumatic disease. Viral serologies and compatible clinical history of exposure often can make the diagnosis at this point and obviate need for further rheumatologic evaluation. Treatment of a viral arthritis usually is limited to symptom relief with nonsteroidal antiinflammatory drugs (NSAIDs) because the conditions are generally self-limited.
Symmetric peripheral polyarthritis is the most characteristic feature of RA but also may be seen in many other autoimmune rheumatic diseases, such as systemic lupus erythematosus (SLE) and psoriatic arthritis. Lupus, which may present with a symmetric polyarthritis, usually is characterized by the presence of other symptoms, such as malar rash, serositis (pleuritis and pericarditis), renal disease with proteinuria or hematuria, central nervous system (CNS) manifestations, as well as hematologic disorders, such as hemolytic anemia, leucopenia, lymphopenia, or thrombocytopenia. Rheumatic fever, which can cause symmetric polyarthritis, is an acute febrile illness lasting only 6-8 weeks. In psoriatic arthritis the pattern of joint involvement varies widely. The vast majority of patients have peripheral joint involvement of more than five joints. Others have a pauciarticular asymmetric arthritis or exclusive distal interphalangeal (DIP) involvement. Inflammation is not limited to the joints but also occurs at the periosteum, along tendons, and at the insertion points into the bone, resulting in the development of "sausage digits," which are typical of psoriatic arthritis (and Reiter syndrome). Although the arthritis can precede the development of a skin rash, the definite diagnosis of psoriatic arthritis cannot be made without the evidence of skin or nail changes typical of psoriasis.
The peripheral polyarthritis of RA most typically involves the wrists and the MCP or PIP joints of both hands; the DIP joints usually are spared. It is useful to contrast the typical pattern of joint involvement of RA from those of degenerative OA. Degenerative joint disease may affect multiple joints, but it occurs in older age groups, usually is not associated with inflammation or constitutional symptoms, and tends not to be episodic. Also, in OA the hand joints most commonly involved are the DIP joints, where the formation of Heberden nodes can be noted (Figure 22-1). Ulnar deviation of the MCP joints is often associated with radial deviation of the wrists; swan-neck deformities can develop as well as the boutonnière deformity (see Figure 22-2). Swan-neck deformity results from contracture of the interosseous and flexor muscles and tendons, which causes a flexion contracture of the MCP joint, hypertension of the PIP joint, and flexion of the DIP joint. In the boutonnière deformity, there is a flexion of the PIP and hyperextension of the DIP joints. These findings are typical of advanced RA.
Morning stiffness or stiffness after any prolonged inactivity is a common feature of many arthritic disorders. However, stiffness that lasts more than 1 hour
Figure 22-1. Rheumatoid arthritis versus
Ulnar deviation of metacarpal-phalageal joint and the proximal intraphalangeal joint
Figure 22-1. Rheumatoid arthritis versus osteoarthritis.
is seen only in inflammatory conditions such as RA and reflects the severity of joint inflammation.
Rheumatoid nodules are subcutaneous nodules typically found over extensor surfaces of the proximal ulna or other pressure points. They only occur in 20-30% of patients with RA but are believed to have a high diagnostic specificity for RA.
Rheumatoid factors (RFs) are immunoglobulins that react to the Fc portion of immunoglobulin (Ig)G molecules. The usual serologic tests used in clinical laboratories detect lgM RFs, which are found in 80-85% of patients with RA. RF is not specific for RA, as it is found in 5% of healthy patients, but it can support the diagnosis when clinical features are suggestive. High RF titers have a prognostic utility for more severe systemic and progressive disease.
Radiologic findings in RA, such as erosion of periarticular bone and cartilage destruction with loss of joint space, may help the diagnosis. On x-rays, the typical findings are joint space narrowing, subchondral polysclerosis, marginal osteophyte formation, and cyst formation. Usually, though, the typical x-ray findings do not develop until later in the disease process after a diagnosis has been made based on clinical findings. Joint deformities in RA occur from several different mechanisms, all related to synovitis and pannus formation with resulting cartilage destruction and erosion of periarticular bone. The structural damage to the joint is irreversible and worsens with disease progression. Multiple different joints may be affected, such as hand, foot, ankle, hip, shoulders, elbow, and cervical spine.
There are several extraarticular manifestations in RA. including vas-culitic lesions with the development of ischemic ulcers, which implies systemic involvement; ocular manifestations with symptoms of keratoconjunctivitis sicca (Sjögren syndrome); respiratory manifestations caused by interstitial lung disease: cardiac manifestations; and several neurologic manifestations, such as myelopathy, related to cervical spine instability. Although not common, the continuous bone erosion may result in an atlantoaxial subluxation with cervical dislocation and spinal cord compression. Entrapment neuropathy may develop, such as carpal tunnel syndrome. Hematologic manifestations include anemia, typically anemia of chronic disease. The combination of RA, splenomegaly, leucopenia, lymphadenopathy. and thrombocytopenia is called Felty syndrome. Felty syndrome is most common with severe nodule-forming RA.
At this stage in the disease process, our patient is presenting with joint complaints, fatigue, and malaise. No other extraarticular manifestations have developed yet. At the very onset of RA. the characteristic symmetric inflammation of the joints and the typical serologic findings may not be evident. Therefore, initially distinguishing RA from other conditions, such as lupus, may be difficult. Usually, the development of extraarticular phenomenon allows the physician to make a more specific diagnosis.
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