Arthritis is a general term used to define a group of conditions that will cause inflammation within a single joint (monoarticular) or multiple joints (polyarticular). Arthritic joints will present with pain, swelling, stiffness, and decreased range of motion. Arthritis is generally classified as either inflammatory or noninflammatory, depending on its underlying cause. Within the United States, about 58.5 million adults have been diagnosed with arthritis, with a higher prevalence among women than men. Some arthritis can also affect children, although arthritis is more common with advanced age, affecting 49.6% of people over 65.
Arthritis-related pain and immobility are the leading cause of disability among adults in the US. Risk factors for developing arthritis include obesity, increasing age, gender, infection, joint or joint injury overuse, smoking, and genetics. There are more than 100 kinds of arthritis and related conditions. This article will discuss six of the most common arthritic conditions.
Osteoarthritis (OA), also referred to as degenerative joint disease or degenerative arthritis, is the most common form of arthritis and the leading cause of disability in the United States. OA is defined by loss of cartilage, joint degeneration, and bone spur formation.
OA most commonly affects weight-bearing joints (hips, knees, feet) and joints of the hands, neck, and lower spine. Inflammation is usually a secondary component of this degenerative process, not an initiating factor.
Historically, OA was thought to be classified as a "wear and tear" arthritis associated with age; however, more recent research suggests that the development of OA occurs at a more complicated molecular level within the joint capsule. The degenerative process of OA is initiated when damage or repeated stress to a joint and its supporting structures. This disrupts the balance between cells and molecules within the joint space that act to build and break down cartilage, resulting in a shift that favors cartilage destruction and a secondary inflammatory immune response. When this occurs over a sustained time, cartilage and bone within the affected joint are lost. (1, 3).
Diagnosis of OA is based on clinical features and radiographic imaging. X-ray is the preferred imaging method to visualize joint space narrowing and osteophytes. Labs are rarely needed to confirm the diagnosis but can help rule out other types of inflammatory joint conditions. Once a diagnosis of OA is made, therapeutic goals include stopping tissue damage and supporting cartilage regeneration, decreasing any present inflammation, and managing symptoms. (2, 4).
Osteoarthritis Risk Factors
- Female sex
- Previous injury or overuse of a joint
- Joint misalignment
Common symptoms of OA include a slow onset of pain within the affected joint(s). OA pain is best characterized by joint pain that is better with rest and worse with activity; this often distinguishes it from other forms of inflammatory arthritis. Joint stiffness usually occurs in the morning and improves 30 minutes after waking. The affected joints will be painful to touch, and bone spurs may be palpable in more advanced stages. A grinding noise with the movement of the joint, called crepitus, is one of the most common signs of osteoarthritis.
Rheumatoid arthritis (RA) is a highly inflammatory condition affecting 1.3 million people in the US, defined as polyarticular symmetrical arthritis of autoimmune origin. Autoimmune disease attacks one's cells by the body's immune system. In RA, the immune system mistakenly targets and destroys the joints' healthy cells. Autoimmune diseases are multifactorial in origin, and genetic and environmental factors can contribute to the hyperactivity of the immune system and disease progression.
Rheumatoid Arthritis Risk Factors
- Female sex
- Family history of RA or other autoimmune diseases
- Personal history of autoimmune disease
If left undiagnosed and untreated, RA will lead to early bone erosion and joint deformation. Diagnosis of RA is facilitated by blood testing, imaging, and clinical presentation.
Rheumatoid Arthritis Symptoms
The hallmark feature of RA is persistent symmetrical arthritis of multiple small joints within the hands and feet, although other joints can be affected. Symptom onset is gradual and progressive, and the early stages of RA will often present with generalized fatigue, fever, joint pain, and weakness. Joint stiffness generally lasts longer than 30 minutes in the morning. As RA progresses, joints will become red and swollen, and several hallmark joint deformities can occur, including ulnar deviation, Boutonnière deformities, and swan neck deformities. (6, 7, 8).
A rheumatoid blood panel is often positive for antinuclear antibodies (ANA), rheumatoid factor (RF), and anti-cyclic citrullinated peptides (CCP). These findings help to distinguish RA from psoriatic arthritis, as discussed below.
RA is a systemic disease, so other organs are often affected.
Common extra-articular manifestations include:
- Eyes: dryness, pain, redness, photosensitivity
- Mouth: dryness, gingivitis
- Skin: nodules
- Lungs: shortness of breath, lung disease
- Heart/Blood Vessels: anemia, vasculitis, pericardial effusion, heart attack, atherosclerosis
- Nerves: numbness/tingling
Psoriatic arthritis (PsA) is an inflammatory seronegative spondyloarthritis that co-occurs with a skin condition called psoriasis. To break down what this means:
- Seronegative: Antibodies measured in the blood are not detected
- Spondyloarthritis: A type of arthritis that attacks the spine and joints in the arms and legs and can involve the skin, intestines, and eyes. This differs from other forms of arthritis because it involves entheses, the sites where ligaments and tendons attach to bones.
- Psoriasis: An inflammatory skin condition characterized by scaly plaque formation on the skin due to the rapid division of skin cells within the epidermis.
PsA affects about 30% of people with psoriasis, and most cases begin on average ten years after the onset of skin symptoms. Unlike many other types of arthritis, PsA affects men and women equally. The exact cause of PsA is unknown, but it is considered autoimmune. Contributing factors may include genetics and environmental factors like obesity, infection, and trauma.
Psoriatic Arthritis Risk Factors
- Psoriasis: Having psoriasis is the single greatest risk factor for developing psoriatic arthritis.
- Family history
- Age: Although anyone can develop psoriatic arthritis, it occurs most often in adults between the ages of 30 and 55.
Psoriatic Arthritis Symptoms
Musculoskeletal symptoms of PsA present mainly in two ways: pain and stiffness of the spine and extremities and bone destruction that causes deformities of the spine, hands, and feet. Usually, the arthritis of PsA is asymmetrical, affecting joints only on one side of the body. Joint pain usually worsens with rest and in the mornings and improves with movement. A hallmark finding is dactylitis, the diffuse swelling of a finger or toe, giving it a sausage-like appearance. (9, 10, 11).
Other PsA symptoms include:
- Nails: uniform pitting and ridging, thickening of the nail bed, yellowing of nails
- Skin: psoriasis, pitting edema
- Eyes: inflammation of the eyes (uveitis, conjunctivitis)
Classification of Psoriatic Arthritis
Psoriatic arthritis is diagnosed with highly specific classification criteria. The criteria consist of established inflammatory articular disease with at least 3 points from the following features:
- Current psoriasis (assigned a score of 2)
- A history of psoriasis (in the absence of present psoriasis; assigned a score of 1)
- A family history of psoriasis (in the absence of current psoriasis and history of psoriasis; assigned a score of 1)
- Dactylitis (assigned a score of 1)
- Juxta-articular new-bone formation (assigned a score of 1)
- RF negativity (assigned a score of 1)
- Nail dystrophy (assigned a score of 1)
Juvenile Idiopathic Arthritis
Juvenile idiopathic arthritis (JIA) is the most common arthritis in children and adolescents, with the onset of symptoms before age 16. The cause of JIA is unknown ("idiopathic"), but it is autoimmune in origin. Genetics play an important role in the development of the disease, and inflammatory molecules TNF-alpha, IL-6, and IL-1 are known to be involved in the inflammatory process at the affected joint spaces. There is no cure for JIA, but remission is possible with the proper treatment, which encompasses medications, complementary therapies, and lifestyle modifications. (12, 13).
Juvenile Idiopathic Risk factors
Some forms of juvenile idiopathic arthritis are more common in girls.
Juvenile Idiopathic Arthritis Symptoms
There are six forms of JIA, each with its unique presentation. Most are more common in girls, with a few exceptions noted below. All subtypes share joint pain, stiffness, redness, and swelling lasting at least six weeks. Joint pain is worse with rest and with waking in the morning. Symptoms may come and go, and the duration of symptom flares varies. (12, 13).
The six types of JIA, and their distinguishing features, are as follows (12, 13):
- Oligoarticular: The most common and mild form of JIA, oligoarticular JIA affects four joints or fewer. Large joints are most commonly affected. It is considered persistent if symptoms last longer than six months and at least five joints become involved after six months. Chronic eye inflammation called uveitis may occur.
- Polyarticular: Responsible for about 25% of JIA cases, this type affects at least five joints within six months of symptom onset and is symmetrical. Both small and large joints can be involved. Depending on lab results, Polyarticular JIA can be further classified as either RF-positive or RF-negative. Uveitis may also be present.
- Systemic: This rare form of JIA affects boys and girls equally. Joint pain is not the first symptom; instead, children will initially present with a high fever and rash lasting for at least two weeks. Inflammation of the internal organs can also be present in more severe cases.
- Psoriatic Arthritis: Psoriasis, pitting of the fingernails, and dactylitis accompany joint pain. Skin symptoms may occur before or after joint pain begins.
- Enthesitis-Related: Similar to PsA, this form of JIA features inflammation at the sites of connection between ligaments and tendons to bone. Enthesitis-related JIA most commonly affects boys, and pain is usually located in the hips, knees, and feet. IBD and uveitis may be involved.
- Undifferentiated: This category includes children with joint pain and symptoms that don't perfectly match the other subtype criteria.
Gout is an inflammatory arthritis caused by hyperuricemia, elevated levels of uric acid in the blood, and the resulting formation of monosodium urate crystals that accumulate within the joints. Uric acid is a metabolic breakdown product of purines, molecules consisting of carbon and nitrogen that are found both inside the human body and in the foods we eat.
Gold standard testing for a definitive gout diagnosis is a joint aspiration to identify urate crystals in the joint space; however, it can be presumptively diagnosed based on the American College of Rheumatology Gout classification criteria if aspiration cannot be performed. Gout management goals include treating acute attacks, preventing recurrent attacks, and lowering uric acid levels to prevent urate crystal deposition.
Gout Risk Factors
Gout is three times more common in men than in women, and the average age of onset is between 40-60 years old. Rarely is gout caused by a primary genetic disorder, which causes higher than normal endogenous uric acid production. More commonly, gout is secondary to other conditions that decrease the excretion of uric acid from the body, such as dehydration, certain medications, lead toxicity, and alcohol abuse (5). Other risk factors include obesity, purine, and fructose-rich diets and comorbid conditions, including hypertension, insulin resistance, and diabetes.
Gout progresses through four clinically distinct stages:
- Asymptomatic Hyperuricemia: In this stage, the patient has a serum uric acid level greater than 7 mg/dL without joint pain or swelling.
- Acute Gout: This stage is characterized by an acute episode of pain, redness, swelling, and impaired range of motion within the affected joint. First acute attacks typically only involve one joint and most commonly affect the big toe's first metatarsophalangeal (MTP) joint. This acute phase is followed by symptom remission.
- Recurrent Gouty Arthritis: Without intervention, acute attacks become more frequent. It is estimated that 60% of patients will have a second attack within one year of the first. More joints commonly become involved during this stage.
- Chronic Tophaceous Gout: At this point in disease progression, joint pain and swelling are constant. There are marked limitations in the joint movement of the affected joints. This stage is also characterized by the formation of tophi and sodium urate deposits in the joints that are large enough to visualize on an x-ray. Chronic gout can destroy the joint space and cause secondary osteoarthritis.
Systemic Lupus Erythematosus (SLE or lupus) is a complex autoimmune disorder of connective tissue that can affect multiple organs and systems in the body. It has a widely variable clinical presentation and disease course depending on the body systems involved, along with genetic predisposition and external environmental factors.
Lupus Risk Factors
Lupus is much more common in women and African American, Asian, and Hispanic populations.
SLE symptoms vary and can affect virtually any organ. Common clinical features include:
- Constitutional: fatigue, weight loss, fever
- Musculoskeletal: symmetrical migratory arthritis, muscle pain
- Skin: hallmark erythematous malar rash ("butterfly rash") on nose and cheeks, light sensitivity, hair loss
- Lungs: inflammation of lung tissue, pulmonary hypertension
- Heart: inflammation of heart tissue, increased risk for cardiovascular disease
- Kidneys: lupus nephritis, kidney failure
- Gastrointestinal: oral lesions, acid reflux, nausea, vomiting, abdominal pain, diarrhea, pancreatitis
- Neurologic: headache, numbness/tingling, seizure, cognitive changes
- Blood: blood disorders, Raynaud's phenomenon
A 2019 study found the most common initial symptoms in patients later diagnosed with lupus are joint pain, malar rash, fever, light sensitivity, hair loss, and fatigue.
Arthritis is a prevalent condition affecting millions in the United States that can cause debilitating pain, swelling, and immobility within the affected joints. Left untreated, arthritis can cause significant disability and impair quality of life. There are many types of arthritis, each with its own distinguishing etiologies and hallmark presentations. All arthritides are multifactorial in origin, with genetic and environmental influencers. Diagnosing the correct type of arthritis is important, as this determines disease prognosis and appropriate treatment recommendations.
Lab Tests in This Article
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