What are the key clinical features to differentiate between osteoarthritis and rheumatoid arthritis in adults presenting with hip pain?

Key clinical features differentiating osteoarthritis (OA) and rheumatoid arthritis (RA) in adults presenting with hip pain:

• Osteoarthritis: Typically affects adults aged 45 or over and presents with activity-related joint pain.
• Morning stiffness, if present, lasts no longer than 30 minutes.
• Joint pain and stiffness are usually localized without systemic symptoms.
• Symptoms tend to be mechanical, worsening with use and improving with rest.
• There is usually no significant joint swelling or systemic inflammation.
• Diagnosis is clinical and imaging is not routinely required unless atypical features are present.

• Rheumatoid arthritis: Can affect adults from age 16 onwards and often involves persistent synovitis affecting multiple joints, including small joints of the hands or feet.
• Morning stiffness typically lasts longer than 30 minutes and is associated with joint swelling, tenderness, and loss of function.
• Systemic symptoms such as fatigue may be present.
• Inflammatory markers (e.g., raised C-reactive protein) may be elevated.
• RA often presents with symmetrical joint involvement and persistent synovitis.
• Referral for specialist assessment is urgent if multiple joints or small joints are involved or if symptoms persist beyond 3 months.

In summary, OA is characterized by localized, activity-related hip pain with brief morning stiffness and absence of systemic inflammation, whereas RA involves prolonged morning stiffness, joint swelling, systemic symptoms, and often multiple joint involvement including small joints, with inflammatory markers elevated ²,³,⁴.