Question

What is the pathophysiology of osteoarthritis and rheumatoid arthritis and the similarities and differences between the disorders?

Answer 1

OSTEOARTHRITIS

Osteoarthritis (OA) is a type of joint disease that results from breakdown of joint cartilage and underlying bone. The most common symptoms are joint pain and stiffness.

The main cell type found in cartilage is the chondrocyte. These cells come from precursor cells called chondroblasts, which get trapped within the developing cartilage in spaces called lacunae. From this site they function to produce all the constituents, such as collagen (designated as type 2), that gives cartilage its functional characteristics. A disadvantage of having the chondrocytes located within these lacunae is that they are unable to migrate to areas of damage. The effect of this is that, consequently, cartilage has a poor propensity to heal. This is further compromised by the presence of the cartilage matrix, which acts as a barrier to immune cells, such as lymphocytes and immunoglobulins, which may assist in the healing process. Similarly, the lack of a blood supply to the cartilage means that new matrix formation is slow, limiting its ability to recover from insult.

So in effect, whilst cartilage has a very unique structure that provides it with useful functional characteristics, it is at the expense of being able to recover from injury. It is this injury which progresses over time to become osteoarthritis, causing the typical symptoms of the disease, including pain, deformity, and ultimately loss of function.

RHEUMATOID ARTHRITIS

Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are involved, with the same joints typically involved on both sides of the body.

Rheumatoid arthritis (RA) is a systemic inflammatory disease mainly characterized by synovitis and joint destruction. Etiology of RA is unknown. Although the impact of genetic factors is obvious, the genetic basis is not sufficient to explain the triggering of the immune insult. The dominant feature is inflammation, primary in synovium. The synovial membrane in RA becomes hyperplastic. There is an increased number of both type synoviocytes and is infiltrated with immune and inflammatory cells: particularly macrophages, B- and T-lymphocytes, plasma cells and dendritic cells. Increased levels of cytokines are present. Cytokines play a central role in the perpetuation of synovial inflammation. The persistence of the chronic inflammatory response in conjunction with ongoing joint destruction (is finding in many patients with RA despite the use of effective anti-inflammatory agents and disease-modifying drugs) probably appears as a direct result of the sustained recruitment, inappropriate retention and impaired apoptosis. RA primarily starts as a state of persistent cellular activation leading to autoimmunity and immune complexes in both joints and other organs where it manifests. The initial site of disease is the synovial membrane, where swelling and congestion leads to infiltration by immune cells. Three phases of progression of RA are an initiation phase, due to non-specific inflammation, an amplification phase, due to T cell activation and chronic inflammatory phase with tissue injury, due to cytokines

RHEUMATOID ARTHRITIS VS OSTEOARTHRITIS

Rheumatoid arthritis is a destructive joint disease that is caused by inflammation in the tissue that normally produces lubrication fluid for joints. When this tissue remains inflamed, it leads to deformity by loosening joint ligaments and to joint destruction by eroding away cartilage and bone.

Osteoarthritis is a noninflammatory joint disease whereby the cartilage of the joint thins, typically asymmetrically -- so only one knee or hand may be affected. The illustration on the previous page demonstrates the difference between a normal joint and those of osteoarthritis and rheumatoid arthritis . While rheumatoid arthritis is a chronic illness, meaning it can last for years, patients may experience long periods without symptoms. However, rheumatoid arthritis is typically a progressive illness that has the potential to cause significant joint destruction and functional disability.

A joint is where two bones meet to allow movement of body parts. Arthritis means joint inflammation. The joint inflammation of rheumatoid arthritis causes swelling, pain, stiffness, and redness in the joints. The inflammation of rheumatoid disease can also occur in tissues around the joints, such as the tendons, ligaments, and muscles.

In some people with rheumatoid arthritis, chronic inflammation leads to the destruction of the cartilage, bone, and ligaments, causing deformity of the joints. Damage to the joints can occur early in the disease and be progressive. Moreover, studies have shown that the progressive damage to the joints does not necessarily correlate with the degree of pain, stiffness, or swelling present in the joints. Rheumatoid arthritis is a common rheumatic disease, affecting approximately 1.3 million people in the United States, according to current census data. The disease is three times more common in women as in men. It afflicts people of all races equally. The disease can begin at any age and even affects children (juvenile idiopathic arthritis), but it most often starts after 40 years of age and before 60 years of age. Though uncommon, in some families, multiple members can be affected, suggesting a genetic basis for the disorder.

EW

SLETTER

Rheumatoid Arthritis (RA)

• Medical Author: William C. Shiel Jr., MD, FACP, FACR
• Medical Editor: Melissa Conrad Stöppler, MD
• Medical Editor: Catherine Burt Driver, MD

Medically Reviewed on 2/13/2018

Table of Contents

• Rheumatoid arthritis (RA) facts
• What is rheumatoid arthritis (RA)?
• Rheumatoid arthritis vs. osteoarthritis
• What are rheumatoid arthritis causes and risk factors?
• What are complications of rheumatoid arthritis?
• What are rheumatoid arthritis symptomsand signs?
• What tests do physicians use to diagnoserheumatoid arthritis?
• What are the stages of rheumatoid arthritis?
• What are rheumatoid arthritis treatmentoptions? What are types of rheumatoid arthritis medications?
• "First-line" rheumatoid arthritis medications
• "Second-line" or "slow-acting" rheumatoid arthritis drugs (disease-modifying anti-rheumatic drugs or DMARDs)
• What are newer rheumatoid arthritis medical treatments?
• Rheumatoid arthritis diet, exercise, therapy, home remedies, and alternative medicine
• What about rheumatoid arthritis and pregnancy?
• What is the prognosis for patients with rheumatoid arthritis?
• Is there a cure for RA?
• What are tips for living with rheumatoid arthritis?
• Is it possible to prevent rheumatoid arthritis?
• What specialists treat rheumatoid arthritis (RA)?
• What new information about RA has come from the 2015 national meeting of the American College of Rheumatology?
• What research is being done on rheumatoid arthritis?
• Are there support groups for people with rheumatoid arthritis?
• Where can people get additional information on rheumatoid arthritis?

• RA Slideshow
• Take the RA Quiz
• RA Friendly Exercises

1/23

Rheumatoid arthritis (RA) facts

• Readers Comments 65

• Rheumatoid arthritis is an autoimmune disease that causes chronic inflammation of the joints and other areas of the body.
• Rheumatoid arthritis symptoms and signs include
  • joint pain, such as in the joints of the feet, hands, and knees,
  • swollen joints,
  • fever,
  • limping,
  • polyarthritis,
  • loss of range of motion,
  • tender joints,
  • loss of joint function,
  • stiff joints,
  • fatigue,
  • joint redness,
  • rheumatoid nodules,
  • anemia,
  • joint warmth,
  • joint deformity, and
  • symptoms and signs that affect both sides of the body (symmetry).
• Rheumatoid arthritis is a chronic disease characterized by periods of disease flares and remissions.
• In rheumatoid arthritis, multiple joints are usually, but not always, affected in a symmetrical pattern.
• Chronic inflammation of rheumatoid arthritis can cause permanent joint destruction and deformity.
• Damage to joints can occur early and does not always correlate with the severity of RA symptoms.
• The "rheumatoid factor" is an antibody that can be found in the blood of 80% of people with rheumatoid arthritis. Rheumatoid factor is detected in a simple blood test. Possible risk factors for developing rheumatoid arthritis include genetic background, smoking, silica inhalation, periodontal disease, and microbes in the bowels (gut bacteria).
• There is no cure for RA. The treatment of rheumatoid arthritis optimally involves a combination of patient education, rest and exercise, joint protection, medications, and occasionally surgery.
• Medications used in the treatment of rheumatoid arthritis include NSAIDs, DMARDs, TNF alpha inhibitors, IL-6 inhibitors, T-cell activation inhibitors, B-cell depleters, JAK inhibitors, immunosuppressants, and steroids.
• Early RA treatment results in a better prognosis.
• Rheumatoid arthritis can affect people of all ages. The cause of rheumatoid arthritis is not known.

Picture of hands affected by rheumatoid arthritis. Notice the joint deformity in the fingers; Image provided by Getty Images

• RA Slideshow
• Take the RA Quiz
• RA Friendly Exercises

2/23

What is rheumatoid arthritis (RA)?

Rheumatoid arthritis definition

Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation of the joints. Autoimmune diseases are illnesses that occur when the body's tissues are mistakenly attacked by their own immune system. The immune system contains a complex organization of cells and antibodies designed normally to "seek and destroy" invaders of the body, particularly infections. Patients with autoimmune diseases have antibodies and immune cells in their blood that target their own body tissues, where they can be associated with inflammation. While inflammation of the tissue around the joints and inflammatory arthritis are characteristic features of rheumatoid arthritis, the disease can also cause inflammation and injury in other organs in the body. Because it can affect multiple other organs of the body, rheumatoid arthritis is referred to as a systemic illness and is sometimes called rheumatoid disease. Rheumatoid arthritis is a classic rheumatic disease. Rheumatoid arthritis that begins in people under 16 years of age is referred to as juvenile idiopathic arthritis or JIA (formerly juvenile rheumatoid arthritis or JRA).

Picture of a joint with rheumatoid arthritis

• RA Slideshow
• Take the RA Quiz
• RA Friendly Exercises

3/23

Rheumatoid arthritis vs. osteoarthritis

• Read Doctor's View
• Readers Comments 1

Rheumatoid arthritis is a destructive joint disease that is caused by inflammation in the tissue that normally produces lubrication fluid for joints. When this tissue remains inflamed, it leads to deformity by loosening joint ligaments and to joint destruction by eroding away cartilage and bone.

Osteoarthritis is a noninflammatory joint disease whereby the cartilage of the joint thins, typically asymmetrically -- so only one knee or hand may be affected. The illustration on the previous page demonstrates the difference between a normal joint and those of osteoarthritis and rheumatoid arthritis.

While rheumatoid arthritis is a chronic illness, meaning it can last for years, patients may experience long periods without symptoms. However, rheumatoid arthritis is typically a progressive illness that has the potential to cause significant joint destruction and functional disability.

A joint is where two bones meet to allow movement of body parts. Arthritis means joint inflammation. The joint inflammation of rheumatoid arthritis causes swelling, pain, stiffness, and redness in the joints. The inflammation of rheumatoid disease can also occur in tissues around the joints, such as the tendons, ligaments, and muscles.

In some people with rheumatoid arthritis, chronic inflammation leads to the destruction of the cartilage, bone, and ligaments, causing deformity of the joints. Damage to the joints can occur early in the disease and be progressive. Moreover, studies have shown that the progressive damage to the joints does not necessarily correlate with the degree of pain, stiffness, or swelling present in the joints.