Chapter 36 Rheumatic Diseases
General Introduction to Rheumatic Diseases
Rheumatic diseases are among the oldest diseases recognized, and more than 100 diverse disorders affect the muscles, bony joints, and supporting structures of the musculoskeletal system (Table 36-1). The classification of rheumatic diseases is often difficult because of their unknown etiology and heterogeneity in their clinical presentation. Some of them are relatively more common, whereas many other conditions are rare (e.g., connective tissue diseases and disorders of collagen metabolism). This chapter focuses on the rheumatic diseases most likely to be seen by a physiatrist, in particular osteoarthritis (OA) and rheumatoid arthritis (RA). Both conditions are variable in manifestation, chronic in status, widespread in nature, and often take a progressive course. Other disorders, such as fibromyalgia, complex regional pain syndrome, and osteoporosis, are described in other chapters in this textbook.
Disease Group | Description | Examples |
---|---|---|
Degenerative and overuse syndromes | Diseases in which the predominant feature is repetitive trauma and/or “wear and tear” of cartilage or periarticular tissues, with minor secondary inflammation | |
Inflammatory arthropathies | Diseases characterized by chronic or recurrent joint inflammation of unknown cause; classified according to the pattern of joint involvement and associated features | |
Extraarticular rheumatism | Poorly understood disorders characterized by chronic or recurrent pain with no evidence of inflammation; primary pathology might be in the perception of pain rather than in the soft tissues | |
Connective tissue diseases | Autoimmune diseases of unknown etiology characterized by multisystem inflammation and damage | |
Inherited disorders of connective tissue | Rare diseases caused by genetic abnormalities affecting the synthesis of structural molecules of the bone and connective tissues | |
Crystal-associated arthropathies | Diseases characterized by acute or recurrent inflammation caused by deposition of crystals in or around the joints | |
Infectious arthropathies | Diseases caused by invasion of joint tissues by microorganisms | |
Postinfectious arthropathies | Diseases triggered by previous exposure to infectious agents |
Kinesiology: The Structure and Function of Joints
The amphiarthrosis joint, sometimes called a fibrocartilaginous joint, is a junction between bones that is formed primarily by a fibrocartilage or hyaline cartilage. The interbody joint in the spine is an example. The amphiarthrosis joint is only slightly movable, allowing relatively restrained movements. It can also transmit and disperse forces between the bones separated by the fibrocartilage or hyaline cartilage.
An Overview of Common Rheumatic Diseases
Osteoarthritis
No single known cause of OA exists. Factors that might contribute to a diagnosis of OA include genetic disposition, age, injury, weight, stress on the joint, and previous surgery involving the joint. Age is the most commonly identified risk factor for OA of all joints. The prevalence of OA increases sharply for women after age 40 years and after age 50 for men. OA of the hand is more prevalent in women, whereas men are slightly more likely to have hip OA. Genetics is likely to contribute to the development of primary OA. Inhibited bone abnormalities or inherited traits (e.g., dysplasia, malalignment) that subject the joint to unusual stress increase the likelihood of its development.
No standard definition of OA is used by researchers and clinicians. A review of the literature showed the validity of the various definitions of hip OA has been barely investigated. Despite precise and extensive development, the American College of Rheumatology (ACR) criteria showed poor reliability and cross-validity in a primary care setting. No agreed criteria exist for knee OA in population studies. The radiographic scoring system of Kellgren and Lawrence15 (Table 36-2) has been most used in the past. Although other methods have been developed, comparisons have not been performed. Data suggest that the presence or absence of a definite osteophyte read on a weight-bearing radiograph is the best method of defining knee OA for epidemiologic studies. Assessment of joint space narrowing might be better used in evaluating the disease severity.
Grade of Osteoarthritis | Description |
---|---|
0 | No radiographic findings of osteoarthritis |
1 | Minute osteophytes of doubtful clinical significance |
2 | Definite osteophytes with unimpaired joint space |
3 | Definite osteophytes with moderate joint space narrowing |
4 | Definite osteophytes with severe joint space narrowing and subchondral sclerosis |
The typical progression of OA involves the following events: (1) loss of cartilage matrix, which makes the joint more susceptible to further injury; (2) alterations to underlying bone associated with wear on the cartilage, with the development of osteophytes at the periphery of the affected joint; (3) release of debris of cartilage or bone fragments into the joint; (4) cartilage breakdown associated with synovial inflammation, which can lead to release of cytokines and enzymes that exacerbate the cartilage damage. Some examples of OA in different joints can be seen in Figure 36-1.
FIGURE 36-1 Typical deformities and x-ray findings in osteoarthritis of the spine (A), hands (B), hip (C), and knee (D).
Box 36-1 lists the criteria for classification of OA of the hand, hip, and knee.
Classification criteria for osteoarthritis of the hand, traditional format
Hand pain, aching, or stiffness, and at least three of the following:
Classification criteria for osteoarthritis of the hip, traditional format
Hip pain and at least two of the following:
Rheumatoid Arthritis
RA is defined as an autoimmune disease in which the joint lining and occasionally other tissues become inflamed as a result of overactivity of the body’s immune system.5,7 RA is a chronic, systemic, inflammatory disorder of unknown etiology that primarily involves the joints. RA begins insidiously with generalized weakness, anorexia, fatigue, and vague musculoskeletal symptoms before the appearance of synovitis. RA affects about 1% of the adult population but causes more than 250,000 hospitalizations annually. RA is one of the most serious and disabling types of arthritic diseases and affects women 2 to 3 times more often than men. Like OA, RA encompasses a combination of events or a pattern of reactions that can result in joint injury.26
Although RA is universal and found in all populations, prevalence and incidence rates vary in different ethnic groups. A low prevalence is found among African blacks, and a high prevalence is seen in rural Germany. Prevalence rates are influenced according to which set of criteria is used to diagnose RA and whether the RA is definite or probable. Genetic studies of RA show that there is a limited concordance of the disease in twins. No specific pattern of inheritance exists, although there is a twofold increase among first-degree relatives of patients with RA. Some examples of its effects on the hands and feet are shown in Figure 36-2.
Review of the literature presents various quantitative measures to assess RA in research trials and clinical care. No single “gold standard” is used to assess and monitor the status of patients with RA. Different measures have been used in research and clinical care, including laboratory tests, radiographic scores, formal joint counts, physical measures of functional status, global measures, and patient self-report questionnaires. These measures or assessment tools can address the activity of the disease, damage to the joint, both activity and damage, or long-term outcomes. Measures of disease activity (e.g., joint swelling) are reversible and can be improved over time, whereas measures of joint damage (e.g., radiographic scores) indicate disease progression.22,23
Goals of RA therapy are to prevent or control joint damage, prevent loss of function, and decrease pain. Treatment measures are aimed at ameliorating inflammation after identifying active disease. Treatment is not considered curative, only palliative, aiming to relieve signs and symptoms of the disease. Management initially includes patient education, disease-modifying antirheumatic drugs (DMARDs) within 3 months, nonsteroidal antiinflammatory drugs (NSAIDs), low-dose systemic steroids, and physical and occupational therapy. Disease activity must be reassessed, and if the response to drugs is inadequate, then methotrexate or a biologic response modifier (BRM) should be considered. Surgery might be an option if drug failure is evident, the patient is more symptomatic, and structural joint damage occurs.
Box 36-2 lists the criteria for classification of RA.
BOX 36-2 American College of Rheumatology Criteria for the Classification of Rheumatoid Arthritis
From Arnett FC, Edworthy SM, Bloch DA, et al: The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis, Arthritis Rheum 31:315-324, 1988.