Acute Monoarthritis

Sudden pain and swelling of a single joint.


  • Site
    • Some diagnoses more characteristically affect particular joints e.g. gout and the 1st MTP joint
  • Timing and onset
    • Sudden onset (seconds-minutes)- suggestive of fracture, internal derangement, trauma or loose body
    • Several hours to several days- Infection (usually days- progressively worsening), crystal deposition disease (usually hours to the worst point then remains painful or improves), other inflammatory arthritis
    • Days to weeks- Indolent infection, osteoarthritis, infiltrative disease, tumour
  • Ask about the nature of the pain
    • Character, exacerbating/relieving factors (in particular, movement)
  • Ask about associated symptoms
    • Red, hot, swollen (crystal arthropathy, inflammatory disease including infection)
    • Fever (infection)
    • Weakness, loss of movement
    • rash, myalgia, headache, visual disturbance
  • Ask whether this has happened before.  Ask whether there were any triggers for the episode.
    • e.g. recent diarrhoea (reactive arthritis); urethritis; trauma;
  • Equally ask about past medical history
    • Psoriasis (psoriatic arthritis); IBD; ocular symptoms
    • Any previous surgery to the joint?

Remember to take a full past medical history and drug history (including anticoagulants- haemarthrosis); Family history; social history (alcohol- gout; occupation- may be suggestive of osteoarthritis)


  • General
    • Check vital signs for SIRS (and thus sepsis)
    • Check the eyes for any inflammation that could hint at an autoimmune/systemic inflammatory cause
    • Look for any rashes/erythema nodosum/gouty tophi
  • Examination of the joint
    • Inspect
      • Any deformity, swelling, redness, periarticular muscle wasting
    • Palpate
      • Any bony swelling, ligamentous swelling or effusion (e.g. patellar tap)
    • Movement
      • Test both active and passive movement
        • True intra-articular problems restrict both whereas peri-articular problems tend to restrict active > passive
        • Maximum pain at the limit of joint movement is more likely to be a true arthritis
        • Pain from movements in particular directions is more suggestive of tendonitis/bursitis
    • NB Remember that some joint pain can be referred from elsewhere, including other joints e.g. hip causing knee pain.  It is important to enquire about and examine these ‘associated’ joints too.


  • All patients with a short history of a hot, swollen and tender joint with restricted movement should be regarded as having septic arthritis until proven otherwise:
    • Joint aspiration for Gram-stain, culture and sensitivity, and WCC is “mandatory” in such patients.  Ideally, this should be done before starting any anitbiotic treatment but if the suspicion is high, this should not prevent antibiotics being prescribed
  • Other investigations include
    • Blood cultures
    • Bloods
      • FBC (WCC), CRP, PV/ESR
      • Urate is normally measured, although low levels does not exclude gout
      • LFTs/U&Es (kidney function) should really be assessed prior to antibiotic treatment
      • Consider autoantibodies/rheumatoid factor if clinical suspicion of connective tissue diseases
    • X-rays and other imaging are not usually that useful in diagnosing the cause


  • Common
    • Septic arthropathy
    • Crystal arthropathy
      • Gout
      • Pseudogout
      • Other
    • Haemarthrosis
    • Avascular necrosis
    • Osteoarthritis
    • Osteomyelitis
    • Overuse
    • Trauma and articular fractures
  • Less common
    • Bone malignancy
    • Connective tissue/autoimmune
      • Spondylitis associated with bowel disease
      • Juvenile rheumatoid arthritis
      • Rheumatoid arthritis (rarely monoarthritic but can be)
      • Psoriatic arthritis
      • Reactive arthritis
      • Sarcoidosis
      • SLE
    • Loose body
    • Synovial chondromatosis

Specific Joints

  • Shoulder
    • Brachial neuritis (referred from neck)
    • Rotator cuff injuries/tendinitis
    • Frozen shoulder (adhesive capsulitis)
    • Acromioclavicular joint problems
  • Elbow
    • Lateral epicondylitis
    • Medial epicondylitis
    • Olecranon bursitis
  • Wrist/Hand
    • De Quervain tenosynovitis
    • Trigger finger (digital tenosynovitis)
  • Hip
    • Lumbosacroiliac conditions (referred from lower back)
    • Trochanteric bursitis
  • Knee/Ankle
    • Prepatellar bursitis
    • Popliteal bursitis
    • Patellar tendinitis
    • Achilles tendinitis

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