Osteoarthritis Diagnosis

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

• Normal exam does not rule out osteoarthritis
• Features that suggest diagnosis of osteoarthritis 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)

Diagnostic Criteria of Osteoarthritis by the American College of Rheumatology (ACR)

Osteoarthritis of the Hand

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

Osteoarthritis of the Knee (Clinical and 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% and specificity of 86%

Osteoarthritis of the Hip

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

• May help exclude other diagnosis and monitor side effects of medications
• Not reliable and required in establishing the diagnosis of osteoarthritis
• Usually normal, except for possible elevated erythrocyte sedimentation rate (ESR) and 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, especially in elderly and 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 and with leukocyte count <2000/mm³

Imaging Procedures

• Assist in diagnosing osteoarthritis
• Suggested for patients ≥45 years, with joint pain especially at movement, and with morning stiffness lasting for >30 minutes

Plain X-rays

• Primary imaging method used to confirm the diagnosis of osteoarthritis, stage its severity and follow its progression
  • Severity of radiographic findings does not correlate well with the severity of the symptoms or the presence of functional disability
  • Absence of radiologic features does not exclude osteoarthritis
  • May be used to exclude other diagnosis (eg trauma)

• Almost always sufficient in diagnosing osteoarthritis
• Radiologic features indicative of osteoarthritis 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 and soft tissue swelling)

• Taken in standing antero-posterior (AP) and lateral position; should be interpreted together with the clinical presentation of the patient

Magnetic Resonance Imaging (MRI)

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

Ultrasound

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