Monarticular pain may originate in a joint, be referred, or originate from periarticular structures (eg, bursitis or tendinitis). Pain from intra-articular structures is often inflammatory arthritis but may be noninflammatory (eg, osteoarthritis, internal derangement).

Acute monarticular joint pain requires particularly rapid diagnosis because some of its causes, particularly infectious (septic) arthritis and crystal-induced arthritis, require rapid treatment. Both of these disorders are inflammatory and cause joint effusions. Crystal-induced arthritis is usually caused by monosodium urate (gout) or Ca pyrophosphate dihydrate crystal deposition disease (pseudogout). Acute monarticular arthritis may occasionally be the initial presentation of psoriatic arthritis or various types of polyarticular inflammatory arthritis. Less common causes of acute monarticular arthritis are disorders such as adjacent osteomyelitis, bone infarcts, foreign bodies, hemarthroses (eg, in hemophilia or coagulopathies), and tumors.

Evaluation

Evaluation should determine whether the joint or periarticular structures are the cause of symptoms and whether there is inflammation. If inflammation is present or the diagnosis is unclear, signs and symptoms of polyarticular and systemic disorders should be sought and all joints examined.

History

Severe joint pain that develops over hours suggests crystal-induced (or less often infectious) arthritis. A previous attack of crystal-induced arthritis with development of similar symptoms suggests recurrence. Risk factors for gout include male sex, older age, and use of diuretics or other drugs that increase uric acid (urate) levels. Risk factors for infection include immunosuppressive or corticosteroid therapy, diabetes, IV drug use, extra-articular foci of infection, tick bite or residence in a Lyme-endemic area, previous intra-articular corticosteroids, and joint prostheses. Urethritis can suggest reactive arthritis or a gonococcal infection, but gonococcal arthritis often develops in patients without symptoms of urethritis.

Pain during rest and on initiating activity suggests inflammatory arthritis, whereas pain worsened by movement and relieved by rest suggests mechanical disorders (eg, osteoarthritis). Gradual onset of pain is typical of RA or noninfectious arthritis but can result from certain infectious arthritides (eg, tuberculous, fungal).

Physical examination

Pain aggravated by passive motion of another structure (eg, passive hip rotation worsening knee pain) suggests referred pain. Pain worse with active than with passive joint motion may indicate tendinitis or bursitis; joint inflammation generally restricts active and passive range of joint motion severely. Tenderness or swelling at only one side of a joint suggests an extra-articular origin (eg, in ligaments, tendons, or bursae); findings on several aspects of the joint suggest an intra-articular cause.

Increased heat and erythema suggest inflammation, but erythema is often absent during inflammation. Although gout can involve many different single joints or combinations of joints, acute, painful monarticular arthritis of the metatarsophalangeal joint of a great toe (podagra) is especially suggestive.

Testing

Bursitis and tendinitis can often be diagnosed without further testing. In severe or unexplained acute monarticular arthritis or bursitis with swelling, synovial fluid examination is essential; arthrocentesis or bursal aspiration confirms effusion and may provide a specific diagnosis (eg, culture of an organism in synovial fluid in infectious arthritis). Finding crystals in synovial fluid confirms crystal-induced arthritis but does not rule out coexisting infection. X‑rays should generally be obtained if bone abnormalities (such as fracture or infection) or Ca pyrophosphate deposition (chondrocalcinosis) or calcific periarthritis is suspected. Other tests are only adjunctive but are obtained depending on what diagnoses are being considered. Blood tests (eg, ESR, antinuclear antibodies, rheumatoid factor) may help determine the cause of noninfectious inflammatory arthritis as described elsewhere in The Manual.

Treatment

The underlying disorder is treated. Joint inflammation is usually treated symptomatically with NSAIDs. Pain without inflammation is usually more safely treated with acetaminophen. Joint immobilization with a splint or sling can sometimes relieve pain. Heat therapy may relieve muscle spasm around joints, and cold therapy may be analgesic in inflammatory joint diseases.

Last full review/revision November 2005