What is arthritis?

What is Arthritis?

Arthritis is characterized by the presence of joint swelling associated with pain or stiffness, representing inflammation of the joints that can result from multiple disease processes. 1

Core Definition and Clinical Recognition

Arthritis fundamentally means joint inflammation, manifesting as joint swelling that is not caused by trauma or bony overgrowth. 1 The term encompasses a broad spectrum of conditions, but the defining clinical feature is synovitis—inflammation of the synovial lining of joints. 1

Key Clinical Features to Recognize Arthritis:

• Joint swelling is the cardinal sign, distinguishing true arthritis from other joint conditions 1
• Pain accompanies the swelling, though pain alone without swelling does not constitute arthritis 1
• Stiffness after inactivity, particularly morning stiffness lasting more than 30 minutes to 1 hour, strongly suggests inflammatory arthritis 1
• Improvement with NSAIDs or corticosteroids rather than opioids suggests inflammatory arthritis 1
• A positive "squeeze test" (pain with compression of metacarpophalangeal or metatarsophalangeal joints) indicates hand or foot joint involvement 1

Major Types of Arthritis

Inflammatory Arthritis (Autoimmune)

Rheumatoid arthritis is the most common autoimmune disease affecting joints, representing a chronic systemic inflammatory disorder. 1

• Affects approximately 1% of the population worldwide, with higher prevalence in persons of European or Asian ancestry 1
• Typical age of onset is around 55 years, with lifetime risk of 3.6% in women and 1.7% in men 1
• Characterized by symmetric polyarthritis with joint swelling, especially of hands and feet 1
• Morning stiffness lasting 1 hour or longer is typical 1
• Results from autoimmune processes with T-cell activation, pro-inflammatory cytokine production, and macrophage imbalance 2, 3
• Leads to progressive cartilage destruction and bone erosion if untreated 2, 4

Degenerative Arthritis (Mechanical)

Osteoarthritis represents a heterogeneous group of conditions leading to joint symptoms associated with defective integrity of articular cartilage and related changes in underlying bone. 5

• Prevalence after age 65 is approximately 60% in men and 70% in women 5
• Etiology is multifactorial with inflammatory, metabolic, and mechanical causes 5
• Environmental risk factors include obesity, occupation, and trauma 5
• Indicates degeneration of articular cartilage with subchondral bone changes and mild intraarticular inflammation 5

Critical Distinction: Inflammatory vs. Mechanical Symptoms

Understanding this distinction is essential for appropriate management:

Inflammatory Symptoms:

• Result from active autoimmune processes in synovial joints 6
• Morning stiffness lasting ≥1 hour 6
• Symmetric joint swelling 6
• Systemic manifestations (fatigue, low-grade fever) 6
• Respond to anti-inflammatory therapy 6

Mechanical Symptoms:

• Result from structural joint damage due to prolonged inflammation 6
• Joint instability and deformity 6
• Limited range of motion not responsive to anti-inflammatory treatment 6
• Pain with weight-bearing or specific movements rather than at rest 6
• Require physical interventions beyond anti-inflammatory therapy 6

When to Refer for Specialist Evaluation

Patients presenting with arthritis of more than one joint should be referred to and seen by a rheumatologist, ideally within six weeks after symptom onset. 1

Specific indications for urgent rheumatology referral include: 7

• Suspected persistent synovitis, even with normal inflammatory markers or negative rheumatoid factor
• Small joints of hands or feet affected
• More than one joint involved
• Delay of three months or longer between symptom onset and seeking medical advice

Impact on Morbidity and Quality of Life

Arthritis, particularly rheumatoid arthritis, is a common cause of disability with significant impact on mortality and quality of life. 1

• More than one-third of patients eventually experience work disability 1
• 80% of patients are working at 2 years, declining to 68% at 5 years 1
• Life expectancy is shortened by 3-5 years, especially with extra-articular disease 1
• Early aggressive treatment prevents irreversible joint damage and improves long-term outcomes 7

Common Pitfall

Do not delay referral based on normal inflammatory markers or negative rheumatoid factor, as early aggressive treatment prevents irreversible joint damage. 7 Joint swelling not caused by trauma warrants evaluation regardless of laboratory findings. 1