Porth's Essentials of Pathophysiology, 4e

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Disorders of the Skeletal System: Metabolic and Rheumatic Disorders

C h a p t e r 4 4

of 7 years. 80,81 There is an increased incidence among girls. The cause is unknown, but there is a history of infection in the 3 months before disease onset in most affected children. Symmetric proximal muscle weak- ness, elevated muscle enzymes, evidence of vasculitis, and electromyographic changes confirming an inflam- matory myopathy are diagnostic for JDM. The rash may precede or follow the onset of proximal muscle weakness. Periorbital edema with swelling and purple red discoloration of the upper eyelid is common. An erythematous (red) papulosquamous (containing both papules and scales) rash may also be present on the dor- sal surfaces of the finger joints and on the extensor sur- faces of the elbows and knees. Ulcerative skin disease is a serious and potentially life-threatening manifestation of JDM. Calcifications can occur in 30%to 50%of childrenwith JDM and are by far the most debilitating symptom. The calcifications appear at pressure points or sites of previ- ous trauma. Juvenile dermatomyositis is treated primarily with corticosteroids to reduce inflammation. DMARDs, such as methotrexate, may be used as a steroid-sparing agent in cases of refractory disease. All children with JDM should avoid exposure to the sun, use a sunscreen with a sun protection factor (SPF) greater than 36, eat a calcium- sufficient diet, and take vitamin D therapy. 81 Rheumatic Diseases in the Elderly Rheumatic disorders are common causes for complaint among elderly persons. 82,83 Pain and severe limitations in function often threaten independence and quality of life. The weakness and gait disturbance that often accom- pany the rheumatic diseases can increase the risk of falls and fracture, causing suffering, increased health care costs, and further loss of independence. Arthritic complaints in the elderly are most frequently associated with degenerative forms of arthritis, such as osteoarthritis, but forms of inflammatory arthritis such as rheumatoid and gouty arthritis are also seen. One form of rheumatic disease that has a predilection for the elderly is polymyalgia rheumatica. Osteoarthritis Osteoarthritis is by far the most common form of arthri- tis among the elderly. 82 It may affect any joint but is most common in the spine and small joints of the hand, particularly the distal interphalangeal joints, and knees, hip, ankle, and shoulder. When the upper extremity joints are affected, activities of daily living, such has holding on to an object, putting on a coat, buttoning a shirt, or turning a key may be a problem. When the lower extremities are involved, climbing and descending stairs and getting out of a chair are difficult. Management of OA in older persons includes both conservative management and surgical correc- tion or joint replacement. 82 Conservative management focuses on rehabilitative and pharmacologic measures. Rehabilitative measures are directed at reducing the

load on the affected joint and maintaining joint mobility. Weight reduction significantly reduces the load in per- sons in whom weight-bearing joints are involved. Although resting painful arthritis joints is helpful in the short term, prolonged inactivity will lead to the more serious problem of immobility. Exercise programs are important to maintain joint motion and strength. Both passive and active exercises should be encouraged. The use of a cane will significantly reduce the loading force in all lower extremities and should be recommended to allow for continuation of a walking program. Attention to environmental hazards to prevent falls is essential. For persons with knee involvement, bracing and orthot- ics provide a shift in the medial knee compartment and, in so doing, may provide considerable relief of pain and improvement in function. The use of appropriate footwear may also reduce joint forces for persons with arthritic involvement of the lower extremities. Pharmacologic treatment is accomplished mainly through the use of NSAIDS and analgesics. 82 As the disease progresses, these medications become less effec- tive and other methods such intra-articular hydrocorti- sone injection may be used. Injection of hyaluronic acid preparations into the knee may be used as an alternative to steroids. Surgical treatment, including joint replace- ment, may be indicated for severely arthritic joints that are unresponsive to conservative treatment. Rheumatoid Arthritis The prevalence of RA increases with advancing age. 83,84 There are two distinct clinical presentations of RA in older persons: RA diagnosed before age 60, and elderly onset RA (EORA), in which the disease is first diag- nosed after age 60. There is a slightly less female pre- dominance and acute onset with marked elevations in inflammatory markers than in persons diagnosed at an earlier age. There is also significant morning stiff- ness, with prominent involvement of the upper extremi- ties, particularly the shoulders. This is in contrast to older persons who have had disease activity for several decades and demonstrate advanced sequelae of the dis- ease and its treatment. Whether either form of RA has a better prognosis than the other is uncertain. Both forms require special considerations in terms of pharmacologic therapy, and both can have a negative impact on the functional status of the elderly. Crystal-Induced Arthropathies The two best-recognized forms of crystal-induced joint disease are caused by the deposition of monosodium urate (gout) and calcium pyrophosphate (pseudogout). 85 Gout typically has its onset in middle-aged adults, whereas pseudogout has an increasing prevalence in older adults and is often associated with unique and atypical features. Gout. The incidence of clinical gout increases with advancing age, in part because of the increased involve- ment of joints after years of continued hyperuricemia.