Makindo Medical Notes

Related Subjects: |Monoarticular arthritis |Polyarticular arthritis |Rheumatoid arthritis |Gout |Pseudogout |Septic Arthritis |Systemic Lupus Erythematosus (SLE) |Enteropathic Spondyloarthritis |Reactive Arthritis

Osteoarthritis: Morning stiffness is a common feature, typically lasting less than 30 minutes, which helps differentiate it from conditions like rheumatoid arthritis. It is associated with progressive cartilage loss.

About

• Osteoarthritis (OA) is a very common condition, increasing in prevalence with age.
• It affects synovial joints due to the gradual loss of articular cartilage.
• More common in women, people of white ethnicity, and those with a familial predisposition.
• There is a strong genetic component—OA has a polygenic heritability.
• Approximately 70% of individuals over the age of 70 are affected.

Main Joints Affected

• Hands, Knees, Hips, and Spinal apophyseal joints.

Aetiology

• Not just "wear and tear"—involves destruction and loss of articular hyaline cartilage.
• There is bone remodeling with sclerosis and cyst formation.
• Attempts at joint repair result in osteophyte (bony spur) formation.
• Potential mechanisms include the activity of metalloproteinases that degrade collagen and proteoglycans.
• Inflammatory mediators like interleukin-1 and TNF may impair collagen production.
• Genetic factors and inherited defects contribute to susceptibility.

Secondary Osteoarthritis

• May result from other conditions or injuries:
  • Previous joint trauma or fractures.
  • Metabolic conditions like haemochromatosis (check ferritin, iron, and transferrin saturation).
  • Endocrine disorders like acromegaly (measure GH following OGTT).
  • Chondrocalcinosis, Ochronosis, Perthes disease, congenital hip dislocation.
  • Systemic diseases: Haemophilia, Sickle cell disease, Rheumatoid arthritis, Gout, and seronegative arthropathies.
  • Joint infections, Paget's disease, avascular necrosis, osteochondrosis, obesity, and other joint injuries.

Clinical Features

• Symptoms worsen with activity and improve with rest.
• Morning stiffness lasts less than 30 minutes; consider alternative diagnoses if it persists longer or in younger patients (<50 years).
• Crepitus (grating sensation) during joint movement, without warmth or significant inflammation.
• Bony tenderness or enlargement on examination.
• Commonly affected joints:
  • Hands: DIPJ (Heberden's nodes) and PIPJ (Bouchard's nodes), 1st MCP joint.
  • Knees: May show varus or valgus deformities; potential for knee effusion or Baker's cyst.
  • Hips: Pain can radiate to the knee.
  • Spine: Cervical and lumbar involvement is common.

Investigations

• FBC: Usually normal. ESR < 40 mm/hr, RF titre < 1:40.
• Radiology: Shows joint space narrowing, subchondral sclerosis, osteophytes, localized osteoporosis, and cyst formation.
• Arthroscopy: May reveal cartilage loss.
• MRI: Useful for detailed assessment of cartilage and joint structures.

Differential Diagnosis

• Age < 45 years: Consider inflammatory arthritis, metabolic disease, or trauma.
• Marked morning stiffness > 1 hour: Suggestive of inflammatory arthritis (e.g., RA).
• Unusual joint involvement (e.g., MCPs): Consider metabolic conditions like haemochromatosis.
• Multiple tender spots: Could indicate fibromyalgia.
• Joint instability or locking: Suggests meniscal or ligamentous injury.
• Systemic symptoms (fever): Raise suspicion for joint sepsis.
• Night pain: Consider malignancy or osteonecrosis.

Management

• Lifestyle and Conservative Measures:
  • Encourage weight loss to reduce BMI, muscle strengthening exercises, and general aerobic fitness.
  • Heat therapy, physiotherapy, and occupational therapy can be helpful.
  • Correct use of walking aids like sticks can reduce joint loading.
• Pharmacological Management:
  • First Line: Oral paracetamol and topical NSAIDs for knee or hand OA. Consider topical capsaicin as an adjunct.
  • Second Line: Oral NSAIDs or COX-2 inhibitors (prescribe with a PPI for gastric protection).
  • Third Line: Combination of NSAID/paracetamol with opioid analgesics for more severe pain. Weigh risks, especially in older adults.
  • Intra-articular Steroids: Can provide 4-6 weeks of pain relief. Sepsis is a rare complication.
• Non-Pharmacological Treatments:
  • Supportive aids like braces, TENS, and shock-absorbing insoles or shoes.
• Surgical Interventions:
  • Consider joint replacement (hip or knee) if conservative measures fail, especially for severe pain or impaired mobility.
  • Total joint replacement can significantly improve pain and function with low complication rates.
• Glucosamine sulphate is not recommended by the 2008 NICE guidelines due to insufficient evidence of benefit.

References

• Osteoarthritis: Care and Management NICE 2020