Osteoarthritis Diagnosis and Management

Diagnostic Criteria

• The American College of Rheumatology suggests that diagnosis of osteoarthritis requires a composite of clinical features, radiographic findings, and exclusion of other conditions, with plain radiography remaining the gold standard for morphological assessment 1
• Diagnosis is based on a combination of factors, including age over 40, family history of nodes, joint space narrowing, and the presence of Heberden nodes, which can increase the probability of having hand OA from 20% to 88% 1
• Weight-bearing views are essential for accurate assessment of lower extremity joints, according to the European League Against Rheumatism 1
• A posteroanterior radiograph of both hands on a single film is adequate for diagnosis of hand osteoarthritis, as recommended by the American College of Rheumatology 1

Laboratory and Radiographic Findings

• Normal laboratory findings in typical osteoarthritis include normal ESR, negative or low-titer rheumatoid factor, and normal C-reactive protein, as reported by the European League Against Rheumatism 1
• Radiographic findings of joint space loss and marginal osteophytes formation are diagnostic features of osteoarthritis, representing the hallmark characteristics of the disease, as stated by the American Academy of Orthopaedic Surgeons and the American College of Rheumatology 2, 1
• Key radiographic features that define osteoarthritis include joint space narrowing, osteophyte formation, subchondral bone sclerosis, and subchondral cysts, which are considered the gold standard for morphological assessment and diagnosis of osteoarthritis, according to the American College of Rheumatology 2
• The following table summarizes the radiographic features of osteoarthritis:

Differential Diagnosis

• Inflammatory arthritis can be differentiated from osteoarthritis by a different pattern of erosions, including non-proliferative marginal erosion and osteopenia, according to the European League Against Rheumatism (EULAR) guidelines 1
• Psoriatic arthritis can be distinguished from osteoarthritis by the presence of proliferative marginal erosion with retained or increased bone density, as noted in the European League Against Rheumatism (EULAR) guidelines 1
• Hemochromatosis arthropathy can mimic osteoarthritis but typically affects 2nd and 3rd metacarpophalangeal joints and ankles, with more rapid progression, according to the Journal of Hepatology 3
• Chronic non-bacterial osteitis can mimic osteoarthritis but typically has more bone marrow edema on MRI, as reported in the Annals of the Rheumatic Diseases 4

Imaging and Diagnosis

• Weight-bearing views are essential for lower extremity joints, and proper positioning is critical for accurate assessment, as recommended by the British Journal of Sports Medicine 5, 6
• The British Journal of Sports Medicine recommends weight-bearing anteroposterior (AP) radiograph of the pelvis and lateral femoral head-neck view for diagnosing hip osteoarthritis, and imaging should be combined with patient symptoms and clinical signs 5, 6
• Plain radiography has high specificity (0.76-0.90) but variable sensitivity (0.44-0.78) for detecting diffuse cartilage damage, femoral osteophytes, acetabular subchondral cysts, and bone attrition of the femoral head, with the best diagnostic performance for bone attrition (AUC 0.82) 6
• Diagnosis should not be made using imaging alone, as stated by the British Journal of Sports Medicine and supported by the American College of Rheumatology 5, 1
• Imaging is not required for patients with typical presentation of osteoarthritis, which includes usage-related pain, short duration morning stiffness, age >40 years, and symptoms affecting one or a few joints, as recommended by the European League Against Rheumatism and the American College of Rheumatology 7, 1

Follow-up and Monitoring

• Routine imaging for OA follow-up is not recommended unless there is unexpected rapid progression of symptoms, as per the American College of Rheumatology and European League Against Rheumatism guidelines 7, 1
• Ultrasound may help differentiate osteoarthritis from inflammatory arthritis, and advanced imaging techniques like MRI are seldom indicated for routine diagnosis, as noted by the European League Against Rheumatism 7, 1