Osteoarthritis

OA Basics & Pathophysiology - Joint Misery Mechanics

• Osteoarthritis (OA): Most common arthritis; chronic, degenerative disorder characterized by cartilage loss and structural joint changes.
• Epidemiology: Leading cause of disability worldwide. Prevalence ↑ with age (often >40 yrs), obesity; significant burden in India.
• Key Pathophysiology:
  • Cartilage: Enzymatic degradation (MMPs) → loss of proteoglycans, Type II collagen damage → fibrillation, erosion.
  • Subchondral bone: Sclerosis (thickening), cyst formation.
  • Osteophytes: Bony outgrowths at joint margins, attempt at repair.
  • Synovium: Mild, secondary inflammation (synovitis) may occur.

⭐ Osteoarthritis is primarily considered a non-inflammatory arthritis, though secondary inflammatory components can be present.

Risk Factors & Clinical Features - Suspects & Symptoms

• Risk Factors:
  • Non-Modifiable: ↑Age, Female gender, Genetics.
  • Modifiable: Obesity (BMI > 30), Joint trauma/overuse, Occupation.
• Clinical Presentation:
  • Insidious onset pain: worse with activity, relieved by rest.
  • Morning stiffness: duration < 30 minutes.
  • Crepitus, restricted range of motion.
  • Bony enlargements (osteophytes).
• Commonly Affected Joints:
  • Hands: DIP (Heberden's nodes), PIP (Bouchard's nodes), 1st CMC joint. 📌 Mnemonic: 'Bouchard's (PIP) Before Heberden's (DIP)' alphabetically & proximally.
  • Knees, Hips, Spine (cervical, lumbar, facet joints).

⭐ The presence of Heberden's nodes (DIP) and Bouchard's nodes (PIP) is highly characteristic of hand osteoarthritis.

Diagnosis & Imaging - Spotting the Wear

• Clinical diagnosis (American College of Rheumatology - ACR criteria supportive).
• X-ray: 📌 LOSS (Loss of joint space, Osteophytes, Subchondral sclerosis, Subchondral cysts). Kellgren-Lawrence (KL) Grade 0-4 (quantifies radiographic severity).
• Labs: Erythrocyte Sedimentation Rate (ESR)/C-reactive Protein (CRP) normal. Synovial fluid: White Blood Cell (WBC) < 2000/μL (non-inflammatory).

⭐ Inflammatory markers (ESR, CRP) are typically normal in Osteoarthritis, distinguishing it from inflammatory arthropathies.

Osteoarthritis (OA) vs. Rheumatoid Arthritis (RA) Highlights

Management Strategies - Easing the Ache

Primary Goals: Pain relief, ↑functional improvement, slowing disease progression.

Non-Pharmacological:

• Patient education
• Weight loss (esp. for knee/hip OA)
• Exercise (aerobic, strengthening, range of motion)
• Physiotherapy & Occupational therapy
• Assistive devices (canes, braces)

Pharmacological:

• First-line: Acetaminophen (up to 3-4 g/day)
• NSAIDs (oral/topical): Lowest effective dose, shortest duration. Consider GI/CV risk; COX-2 inhibitors an option.
• Intra-articular corticosteroids: For acute flares.
• Intra-articular Hyaluronic acid: Viscosupplementation (controversial efficacy).
• Duloxetine: For chronic pain, esp. with neuropathic component.
• Avoid long-term opioids.

Surgical (Advanced OA):

• Arthroscopy (limited role)
• Osteotomy
• Arthroplasty (joint replacement for hip/knee)

⭐ Weight loss of even 5-10% of body weight can significantly reduce pain and improve function in overweight individuals with knee OA.

High‑Yield Points - ⚡ Biggest Takeaways

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