Porth's Essentials of Pathophysiology, 4e

1127

Disorders of the Skeletal System: Metabolic and Rheumatic Disorders

C h a p t e r 4 4

elevated ESR. The person also may have a mild normo- cytic normochromic anemia. HLA typing is not diag- nostic of the disease and should not be used as a routine screening procedure. Radiologic evaluations help dif- ferentiate ankylosing spondylitis from sacroiliitis due to other diseases. However, x-ray images may be normal in early disease. One important advance in diagnosis of ankylosing spondylitis is the use of magnetic resonance imaging (MRI) to assess sacroiliac changes. 51 Whereas plain radiographic images can detect structural changes such as joint erosion and subchrondral bone sclerosis seen in the late stage of the disease, MRI allows for the visualization of synovial fluid, synovitis within the sac- roiliac joint, and subchondral bone edema seen in ear- lier stages of the disease. 51 Treatment of ankylosing spondylitis is directed at controlling pain and maintaining mobility by suppress- ing inflammation. 54 Proper posture and positioning are important. This includes sleeping in a supine position on a firm mattress and using one small pillow or no pillow. A bed board may be used to supply additional firmness. Therapeutic exercises are important to assist in maintaining motion in peripheral joints and in the spine. Muscle-strengthening exercises for extensor mus- cle groups also are prescribed. Swimming is an excellent general conditioning exercise that avoids joint stress and enhances muscle tone. Immobilizing joints is not recom- mended. Maintaining ideal weight reduces the stress on weight-bearing joints. Deep breathing exercises and avoidance or discontinuation of smoking should be emphasized. Pharmacologic treatment includes the use of NSAIDs to reduce inflammation, relieve pain, and reduce mus- cle spasm. Disease-modifying antirheumatic drugs are potential second-line therapies, but their efficacy in anky- losing spondylitis is unproven. Sulfasalazine and metho- trexate have not shown benefit for spondylitis-associated back pain, but have shown efficacy for peripheral joint involvement. Anti–TNF- α therapies, including etaner- cept, infliximab, adalimumab, and golimumab, have demonstrated rapid effectiveness in reducing both the axial and peripheral symptoms of ankylosing spondyli- tis, as well as improving quality of life. 54 The disease process in ankylosing spondylitis var- ies considerably among individuals. Exacerbations and remissions are common; almost all persons have persis- tent symptoms over decades. Fortunately, most of those affected are able to lead productive lives. Progression during the first decade of the disease tends to predict the prognosis. Reactive Arthritis Reactive arthritis is an inflammatory joint disorder that arises after certain inciting gastrointestinal or genitouri- nary tract infections and manifests as a sterile oligoar- thritis, typically of the lower extremities. 55 Most cases of reactive arthritis develop after either a gastrointes­ tinal infection ( Salmonella, Shigella, Campylobacter, or Yersinia ) or sexually transmitted infection ( Chlamydia trachomatis ). The infecting agents cannot be cultured

and are not viable after reaching the joints. A clinically indistinguishable syndrome can occur without anteced- ent infection, suggesting that subclinical infection or some other unrecognized agent can precipitate reactive arthritis. Reiter syndrome is a form of reactive arthritis defined by a triad of arthritis, nongonococcal urethritis or cervicitis, and conjunctivitis. 3 Enteropathic arthritis is a reactive arthritis that is associated with inflamma- tory bowel disease (i.e., Crohn disease and ulcerative colitis) or triggered by enterogenic bacteria. Clinical Manifestations. Reactive arthritis is most commonly asymmetric and frequently involves the lower extremities. Symptoms typically start within 1 to 4 weeks of the initial infection. Hip disease is uncom- mon and involvement of the upper extremities is rare. The joints are typically warm, swollen, and tender. Systemic manifestations including fever and weight loss are common at the onset. Enthesitis is a common fea- ture of reactive arthritis. The Achilles tendon and plan- tar fascia are the most common sites of involvement, but pain in the iliac crests, ischial tuberosities, and back may occur. This aspect of the disease can be disabling, with marked restriction in weight bearing and ambu- lation. Extra-articular lesions are common and include circinate balanitis (shallow ulcers on the glans or shaft of the penis), stomatitis (e.g., painless oral ulcers on the hard palate or tongue), and keratoderma blennorrhagi- cum (a papulosquamous rash most commonly affecting the palms of the hands and soles of the feet [Fig. 44-9]). While most of the signs and symptoms disappear within days or weeks, the arthritis may persist for several months, and in a small number of cases, it may follow a continuous and unremitting course. Treatment. The treatment is largely symptomatic. NSAIDs are used in treating the arthritic symptoms. 55 Vigorous treatment of possible triggering infections is thought to prevent relapses of reactive arthritis, but in many cases the triggering infection passes unnoticed or

FIGURE 44-9. Keratoderma blennorrhagica of soles due to reactive arthritis (Reiter syndrome). (From the Centers for Disease Control and Prevention Public Health Images Library. No. 6950. Courtesy of M. F. Rein.)