Medically Fit For Exams
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Osteoarthritis

Definition

Damage to articular cartilage and bone, causing pain and stiffness. Is generally associated with ageing and overuse.

 

Risk factors

  • Age >55
  • Obesity
  • Physical occupation
  • Previous joint damage, eg fracture
  • Family history

 

Differential diagnosis

  • Bursitis
  • Gout
  • Psoriatic arthritis
  • Rheumatoid arthritis
  • Osteoporosis
  • Musculoskeletal injury
  • Fracture
  • Cancer

 

Epidemiology

  • Strongly associated with age: 33% 45-65, 49% over 75, even higher proportion have radiological changes without symptoms
  • Affects women more than men, 3:2
  • More common in Caucasian and Native American than Black
  • WHO: one of the top 10 leading causes of disability

 

Aetiology

  • Previously thought to be simply ‘wear and tear’, but this is now thought to be overly simple
  • A result of imbalance between stress and capacity/strength – load exceeds critical stress force
  • Some genetic predisposing factors

 

Clinical features

  • Generally only one joint at a time – asymmetrical
  • Affects larger joints eg:
    • Hip
    • Knee
    • Spine
    • DIP
  • Cool joints, minimal swelling
  • Tender and achey joints
  • Morning stiffness <30 mins
  • Exacerbated by use/exercise, relieved by rest
  • Crepitus

 

Pathophysiology

  • Degradation of cartilage: increased water, decreased proteoglycans à decreased elasticity
  • Chondrocyte death, remaining chondrocytes multiply: ‘cloning’, which results in islands of aggregated chondrocytes
  • Proteases break down cartilage and matrix
  • Increased catabolic cytokines, eg IL-1, decreased anabolic cytokines eg IGF-1
  • Fibrillation: cracks appear in cartilage, allow synovial fluid in to bone – cause secondary synovitis, and vascularisation
  • Osteoblast activation causes osteophytes and subchondral ossification
  • Eburnation (bone becomes smooth from bone-on-bone grinding)
  • Bone cysts are a result of synovial fluid entering the bone

 

Investigations

  • X-ray
    • Joint space narrowing
    • Subchondral sclerosis
    • Bone cysts
    • Osteophytes
  • CRP and ESR to rule out inflammatory cause

 

Management

  • Local analgesics are first line:
    • Topical NSAIDS
    • Capsaicin (chili cream)
  • Paracetamol added if necessary
  • Interarticular corticosteroid injections – often give pain relief last weeks to months
  • Oral NSAIDS and opioids if necessary
  • Surgical:
    • Joint replacement
  • Physical therapy
  • Lifestyle advice:
    • Healthy diet
    • Exercise
    • No smoking

 

Prognosis

  • Doesn’t significantly affect life expectancy, although osteoarthritis tends to be progressive, and progressively disabling. More joints may become affected
Osteoarthritis.docx
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