osteoarthritis
OSTEOARTHRITIS

Osteoarthritis is a chronic progressive disease where there is degeneration & loss of articular cartilage that occurs together with new bone formation at the joint surfaces and margins, that causes pain and deformity.

The patient experiences pain, stiffness, decreased movement, inflammation and crepitus.

The pain is usually aggravated by pain and relieved by rest.

Diagnosis

  • Clinical diagnosis based on history & physical exam, with laboratory & radiologic investigations requested to exclude other diagnosis

Physical Examination

  • Normal exam does not rule out OA
  • Features that suggest diagnosis of OA include:
    • Tenderness usually over the joint
    • Crepitus on joint movement
    • Limited range of motion
    • Bony enlargement of the finger joints (eg Heberden’s or Bouchard’s nodes)
    • Pain on passive range of motion
    • Deformity (eg angulation in the hand joints, varus, valgus)
    • Joint instability
    • Periarticular muscle weakness (ie quadriceps muscle)

Assessment

Diagnostic Criteria of OA by the American College of Rheumatology

OA of the Hand

  • Hand pain, aching or stiffness for most days or prior month plus at least 3 of the following features:
    • Hard tissue enlargement on ≥2 of selected joints [bilateral 2nd or 3rd distal interphalangeal (DIP), 2nd & 3rd proximal interphalangeal (PIP) or 1st carpometacarpal joints]
    • Hard tissue enlargement of ≥2 DIP joints
    • <3 swollen metacarpophalangeal joints
    • Deformity of at least 1 of selected joints (bilateral 2nd or 3rd DIP, 2nd & 3rd PIP or 1st carpometacarpal joints)
  • With sensitivity of 94% & specificity of 87%

OA of the Hip

  • Hip pain for most days or prior month plus at least 2 of the following features:
    • ESR <20 mm/hour
    • Presence of femoral & acetabular osteophytes on X-ray
    • Presence of superior, axial, &/or medial joint space narrowing on X-ray
  • With sensitivity of 89% & specificity of 91%

OA of the Knee (Clinical & Radiographic Features)

  • Knee pain plus 1 of the following features:
    • Patient >50 years old
    • Stiffness <30 minutes
    • Crepitus
    • Presence of osteophytes on X-ray
  • With sensitivity of 91% & specificity of 86%

Laboratory Tests

  • Not reliable in establishing the diagnosis of OA
  • May help exclude other diagnosis & monitor medications
  • Usually normal, except for possible elevated erythrocyte sedimentation rate (ESR) & anemia, which are common in the elderly
  • Should consider obtaining complete blood count (CBC), liver function test (LFT), creatinine (Cr) level before starting therapy with NSAIDs, esp in elderly & in patients with other chronic illness
  • Aspiration of synovial fluid may be done to exclude other diagnosis such as septic arthritis, gout, pseudogout
    • Usually clear, viscous & with leukocyte count <2000/mm3

Imaging

Imaging Procedures

  • Assist in diagnosing OA
  • Suggested for patients ≥45 years, with joint pain esp at movement, & with morning stiffness lasting for >30 minutes

Plain X-rays

  • Primary imaging method used to confirm the diagnosis of OA, stage its severity & follow its progression
    • Severity of radiographic findings do not correlate well with the severity of the symptoms or the presence of functional disability
    • Absence of radiologic features does not exclude OA
    • May be used to exclude other diagnosis (eg trauma)
  • Almost always sufficient in diagnosing OA
  • Radiologic features indicative of OA but may not be observed in early disease include the following:
    • Joint space narrowing which is often irregular or asymmetric
    • Subchondral sclerosis which appears as an increased density in subchondral bone
    • Bony proliferation with the presence of osteophytes/spurs
    • Cysts in subchondral marrow adjacent to or sometimes remote from the joint which is usually seen in late cases
    • Soft tissue changes (eg small effusions, calcification & soft tissue swelling)
  • Taken in standing antero-posterior (AP) & lateral position; Should be interpreted together with the clinical presentation of the patient

Magnetic Resonance Imaging (MRI)

  • Used to study joints, cartilage, subchondral bone & synovial tissue simultaneously
  • May be useful in studying the secondary causes of OA (ie meniscal tear, previous ligament injury) or identifying any intraarticular loose body

Ultrasound

  • May be useful in investigating alterations in joint structure & in guiding intra-articular steroid injections but should not be used routinely
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