Osteoarthritis

About

  • Very common seen with increasing age
  • Affects the synovial joints with loss of cartilage
  • Commoner in whites and familial tendency
  • Strong heritability - polygenic

Joints affected

  • Hand, Knee
  • Hips, Spinal apophyseal joints

Aetiology

  • Not just "wear and tear"
  • Destruction and loss of articular hyaline cartilage
  • There is sclerosis and cyst formation due to adjacent bone remodeling
  • Attempts at repair lead to osteophyte formation

Secondary OA may result from other causes

  • Trauma with previous fractures through the joint
  • Metabolic diseases, Haemochromatosis - check ferritin and Iron and transferrin saturation
  • Chondrocalcinosis, Acromegaly - Measure GH following OGTT
  • Ochronosis - see below
  • Systemic diseases : Haemophiliacs, Sickle cell disease, Joint damage, Rheumatoid arthritis, Gout, Seronegative arthropathies
  • Septic arthritis, Paget's disease, Avascular necrosis, Thiemann's disease
  • Osteochondrosis affecting the hands, Obesity, Previous fractures and trauma
  • Perthes disease, Congenital dislocation of the hip

Clinical

  • Activities which worsen with activity and decrease on rest
  • Morning stiffness < 30 minutes
  • Age > 50
  • Crepitus on joint movement
  • Bony tenderness on examination
  • Bony enlargement on examination
  • No palpable warmth on examination
  • Hands : DIP and 1st MCP
  • Foot 1st MTP
  • Spine, hips and knees
  • Heberden's nodes at DIP
  • Bouchard's nodes at the IPJ
  • Knee - varus and valgus deformities +/- knee effusion
  • Baker's cyst behind knee

Investigations

  • ESR < 40 mm/hr
  • RF titre < 1:40
  • Radiology : Joint narrowing, sclerosis, osteophytes, localised osteoporosis, cyst formation
  • Arthroscopy may show cartilage destruction

Differentials

  • Age < 45 consider inflammatory arthritis, severe trauma, metabolic disease
  • Marked early morning stiffness > 1 hour - inflammatory arthritis
  • Unusual joints eg MCPs - Metabolic disease eg haemochromatosis
  • Multiple regional pains 'tender spots' - fibromyalgia
  • Joint locking or giving way - meniscal or ligamentous injury
  • Fever or systemic upset - consider joint sepsis
  • Warm and erythema - sepsis or crystals
  • Pain mainly at night - malignancy, osteonecrosis

Management

  • Rest and analgesia but careful exercise to maintain muscle bulk
  • Cardiovascular exercise, quadriceps strengthening
  • Weight loss to reduce body mass index
  • Heat therapy is useful, physiotherapy and OT
  • Correct use of walking stick can reduce hip loading by 1/5th
  • Paracetamol is first line agent but NSAIDs and weak Opiates may be needed
  • Glucosamine sulphate may be added
  • Topical NSAIDs or Capsaicin can help knee and had OA
  • Intra articular steroids can give approximately 4 to 6 weeks of pain relief. Sepsis is a very rare complication.
  • Surgery - joint replacement effective for Hip and Knee
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