Clinical investigations from the RACP

How to approach the patient with a painful swollen joint

Clinical investigations from the RACP

How to approach the patient with a painful swollen joint

Sean O’Neill, Peter P Youssef

Abstract

There are many potential causes of a single painful joint. This article outlines an approach to the history, examination and investigation of patients aged between about 14 and 40 years, and considers the likely differential diagnoses.

Key Points

  • The most common causes of a painful swollen joint are trauma, infection and crystalline arthritis. The approach to evaluation should focus on excluding conditions that can rapidly lead to joint destruction (particularly bacterial infection).
  • A careful history and physical examination can usually exclude most causes of joint pain and swelling.
  • Plain x-ray is mandatory in patients with a history of significant trauma. It is also required in the presence of focal bone tenderness in order to exclude a tumour.
  • Aspiration of synovial fluid is the most useful investigation in patients with an acutely painful swollen joint, and is mandatory if septic arthritis is suspected. The results of the white cell count, crystal identification, Gram stain and culture are often diagnostic.