1. Pathophysiology:

Osteoarthritis (OA): A degenerative joint disease characterised by the breakdown of cartilage, leading to "wear and tear." It primarily affects weight-bearing joints such as the knees, hips, and spine. The joint damage is mechanical, with little or no systemic involvement.

Rheumatoid Arthritis (RA): An autoimmune disease where the immune system attacks the synovial membrane lining the joints, causing inflammation, joint swelling, and damage. RA often affects smaller joints like the fingers and wrists and is systemic, meaning it can involve other organs.

2. Symptoms:

OA: Pain and stiffness worsen with activity and improve with rest. There may be joint swelling, reduced range of motion, and crepitus (a grinding sensation).

RA: Morning stiffness lasting more than an hour, symmetric joint involvement, swelling, warmth, and redness. Systemic symptoms like fatigue, fever, and weight loss are common.

3. Diagnosis:

OA: Diagnosed through clinical examination and imaging (X-ray showing joint space narrowing, osteophytes, and subchondral sclerosis).

RA: Diagnosed using blood tests (e.g., rheumatoid factor [RF], anti-cyclic citrullinated peptide [anti-CCP] antibodies) and imaging showing joint erosion and soft tissue swelling.

Management of Osteoarthritis

Lifestyle Modifications: Weight loss, regular low-impact exercises (e.g., swimming, cycling).

Medications:

Paracetamol or NSAIDs (topical or oral) for pain relief.

Intra-articular corticosteroid injections for acute flares.

Duloxetine for chronic pain in some cases.

Non-Pharmacological: Physical therapy, orthotics, and braces.

Surgical Options: Joint replacement (e.g., knee or hip arthroplasty) in severe cases.

Pitfalls:

Long-term NSAID use can lead to gastrointestinal, renal, and cardiovascular side effects.

Over-reliance on rest can lead to joint stiffness and muscle atrophy.

Management of Rheumatoid Arthritis

Medications:

DMARDs (Disease-Modifying Antirheumatic Drugs): Methotrexate is the first-line treatment.

Biologic DMARDs: TNF inhibitors (e.g., adalimumab, etanercept) for refractory cases.

Corticosteroids: For acute flares, though long-term use is avoided due to side effects.

NSAIDs for symptom relief, but they do not modify disease progression.

Non-pharmacological: Occupational therapy, physical therapy, and lifestyle modifications.

Surgical Options: Synovectomy or joint replacement in advanced cases.

Pitfalls:

Delayed diagnosis can lead to irreversible joint damage.

Immunosuppression from DMARDs and biologics increases infection risk.

Long-term steroid use can lead to osteoporosis and other complications.

Summary

OA is a mechanical issue due to joint wear, while RA is an autoimmune condition.

OA treatment focuses on symptom management, while RA treatment aims to control the autoimmune response and prevent joint damage.

Mismanagement or delays in treatment, especially in RA, can lead to significant morbidity. Regular monitoring is essential for both conditions to mitigate the side effects of therapy.