How can I differentiate between osteoarthritis and other types of arthritis in a patient presenting with joint pain?

To differentiate osteoarthritis (OA) from other types of arthritis in a patient presenting with joint pain, consider the following clinical features:

• Age and symptom onset: OA typically presents in people aged 45 or over with activity-related joint pain and either no morning stiffness or morning stiffness lasting no longer than 30 minutes ¹.
• Morning stiffness duration: Prolonged morning stiffness (lasting more than 30 minutes) suggests inflammatory arthritis rather than OA ¹.
• Joint characteristics: OA usually involves gradual onset of joint pain, stiffness, and reduced function without significant joint swelling or redness. In contrast, inflammatory arthritis (e.g., rheumatoid arthritis) often presents with joint swelling, warmth, and prolonged stiffness ¹,⁴.
• Rapid onset and severe pain: Sudden onset of severe pain, redness, and swelling, especially in the first metatarsophalangeal joint, suggests gout rather than OA ⁴.
• Presence of atypical features: Features such as rapid worsening of symptoms, hot swollen joints, or systemic symptoms may indicate other diagnoses like septic arthritis or inflammatory arthritis and warrant further investigation ¹,⁴.
• Imaging and investigations: Routine imaging is not recommended to diagnose OA unless atypical features or diagnostic uncertainty exist. For gout or inflammatory arthritis, joint aspiration and serum urate measurement may be necessary ¹,⁴.

Summary: Clinical diagnosis of OA relies on age, activity-related joint pain, and short morning stiffness, while other arthritis types often have prolonged stiffness, joint swelling, redness, or rapid symptom onset. Use targeted investigations if diagnosis is uncertain or atypical features are present ¹,⁴.