Osteoarthritis Diagnosis
Diagnosis
- Clinical diagnosis based on history and physical exam, with laboratory and radiologic investigations requested to exclude other diagnosis
Physical Examination
- 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)
Assessment
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%
Laboratory Tests
- 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
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