Acute polyarthritis

What is acute polyarthritis?

Acute polyarthritis has a very wide differential diagnosis, presenting significant diagnostic difficulties. This article also considers conditions which may cause polyarthralgia which can present in a similar fashion to the inflammatory diseases.

Definitions

Acute monoarthritis - acute inflammation of a single joint; the most important differential diagnosis is septic arthritis.

Oligoarthritis - more than one but fewer than five joints are affected.

Polyarthritis - five or more joints are affected.

History

See also the separate Aching joints - assessment, investigations and management in primary care and Rheumatological history, examination and investigations articles.

Careful clinical assessment should give a differential diagnosis which can be further narrowed down by appropriate investigations. Autoantibody tests can be misleading if not considered in the context of the clinical presentation. They are best used to confirm a clinical suspicion, rather than as suggesters of a diagnosis and should not be requested if you are not clear which condition you are looking to diagnose or exclude by a particular test.

Conditions more commonly considered to be chronic and indolent can present floridly in the acute phase. It can take time for a disease to evolve into its classical pattern and for the decision to be reached as to whether it is a chronic condition or a one-off phenomenon. In some cases a definitive diagnosis may never be reached. ¹

• Details such as age, sex, ethnic origin and occupation can give useful diagnostic clues. For example, juvenile idiopathic arthritis is the most common arthritis in children.

• Family history may be present in cases of rheumatoid arthritis (RA), seronegative arthropathies and osteoarthritis (OA).

• Character of the pain is not always discriminatory in diagnostic terms; acute joint swelling may indicate an inflammatory condition.

• Speed of onset and severity at the start may help - gout tends to come on abruptly, whereas RA is usually more gradual. Similarly, gout tends to cause very severe, excruciating pain.

• Diurnal variation of symptoms is important to establish. An inflammatory arthritis tends to be worse on waking and eases as the day goes on. Mechanical pain tends to have the opposite effect. Most causes of polyarthritis are inflammatory, with osteoarthritis being the exception.

• Migratory arthritis (flitting from joint to joint over a period of days) might suggest gonococcal infection, rheumatic fever (RF), sarcoidosis, systemic lupus erythematosus (SLE), Lyme disease or bacterial endocarditis.

• The pattern of joint involvement may be useful in suggesting a diagnosis. For example:

  • OA of the hand affects the distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints but spares the metacarpophalangeal (MCP) joints.

  • RA affects the MCP and PIP joints but spares the DIP joints.

  • Psoriatic arthritis, crystal arthropathies and sarcoidosis can affect all these joints.

  • Large weight-bearing joints and facet joints of the spine are often affected by OA.

  • Axial involvement in younger patients suggests a seronegative arthropathy such as ankylosing spondylitis or inflammatory bowel disease-associated arthropathy.

• Symmetrical joint involvement tends to occur in systemic syndromes such as RA, SLE, viral arthritis and drug/serum sickness reactions.

• In asymmetrical joint involvement consider gout, septic arthritis, psoriatic arthritis and reactive arthritis.

• Extra-articular symptoms should be asked about and can aid diagnosis. The eyes, parotid glands, skin, mouth, genitals and muscles can all be affected by rheumatological diagnoses.

• Take a full drug history - some drugs (eg, hydralazine, procainamide, quinidine and minocycline) can cause a lupus-like syndrome and there have been reports of a variety of drugs associated with polyarthralgia (eg, moxifloxacin). ^{2 34}

• A direct enquiry should be made as to the presence of systemic symptoms such as fever and weight loss, as well as extra-articular features as given in the table.

Examination

• Check the temperature if concerned about infection.

• Nail changes (eg, pitting) may suggest psoriatic arthropathy.

• Look at the eyes for signs of inflammation.

• Check major lymph nodes for evidence of lymphadenopathy.

• Check the skin for rashes (eg, psoriasis, SLE) and evidence of vasculitis. Feel extensor aspects of forearms for nodules. Check shins for evidence of erythema nodosum.

• Cardiac examination - listen for murmurs if there is reason to suspect rheumatic fever.

• Abdominal examination may reveal evidence of hepatomegaly and/or splenomegaly.

• Examine other systems as indicated by the history and clinical hypotheses.

• Joint examination:

  • Look for signs of inflammation in the joint, such as heat, tenderness and synovial thickening.

  • Establish whether there the affected joints are symmetrical or asymmetrical.

  • Active and passive movements of affected joints and the degree of pain and/or crepitus may also be helpful. However, crepitus and pain will not differentiate between inflammatory and non-inflammatory causes of joint pain. They may, however, give some indication as to the degree of damage.

  • Also examine the structures around the joint and determine if the symptoms are intra-articular or periarticular.

Differential diagnosis

The diagnoses below are not exhaustive but cover the vast majority of causes of polyarthritis.

Investigations

• Where there is any suspicion of septic arthritis, immediate aspiration of synovial fluid should be carried out; referral for this should not be delayed to wait for blood tests.

• Blood tests - FBC, ESR, CRP and U&E are useful screening investigations which give diagnostic clues.

• Autoantibodies can help to confirm a diagnosis but are often relatively nonspecific or insensitive.⁶ They should be interpreted in the context of the clinical presentation, preferably with specialised rheumatological input for the less common markers.

• Rheumatoid factor if there is synovitis on clinical examination. Consider measuring anti-cyclic citrullinated peptide (anti-CCP ) antibodies in adults with suspected RA if they are negative for rheumatoid factor.⁷

• Radiology - X-rays play a variable role in their contribution to diagnosis but are a useful first-line investigation. X-ray the hands and feet in adults with suspected RA and persistent synovitis.⁷ Other imaging modalities may need to be conducted with rheumatological/radiological advice.

• Urinalysis indicates any renal involvement.

Management of acute polyarthritis

This is directed at the underlying diagnosis. See the links to the individual diagnoses for detail.

Symptomatic treatment of inflammatory conditions with non-steroidal anti-inflammatory drugs should be considered whilst awaiting the evolution of an arthritis, where there are no contra-indications or significant drug interactions. It is generally not ideal to give prednisolone in this situation, as that can make it harder to make a definitive diagnosis in secondary care. Discussion with a specialist would be wise if considering this.

Where there is a significant inflammatory illness as revealed by clinical severity and CRP/ESR, etc, early referral for disease-modifying interventions can significantly reduce joint pathology in some conditions.

For patient with possible RA, the National Institute for Health and Care Excellence (NICE) recommends:⁷

• Refer for specialist opinion any adult with suspected persistent synovitis of undetermined cause.

• Refer urgently (even with a normal acute-phase response, negative anti-CCP antibodies or rheumatoid factor) if any of the following apply:

  • The small joints of the hands or feet are affected.

  • More than one joint is affected.

  • There has been a delay of three months or longer between onset of symptoms and seeking medical advice.