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Emergency and Acute Medicine – Joint Pain and Fever
Overview and Definitions
Joint pain accompanied by fever suggests an inflammatory or infectious process and requires prompt evaluation. Joint involvement may be monoarticular, oligoarticular, or polyarticular and may be symmetric or asymmetric. Arthritis refers to inflammation of a joint and is a clinical finding rather than a diagnosis, whereas arthralgia denotes joint pain without objective inflammation. Acute joint disorders last less than six weeks, while chronic disorders persist beyond this duration.
Clinical Approach
The presence of fever narrows the differential diagnosis toward infectious, crystal-induced, immune-mediated, or reactive etiologies. Noninflammatory disorders such as osteoarthritis or fibromyalgia are rarely associated with fever. History should focus on onset and tempo of symptoms, recent infections, travel, trauma, sexual exposure, immunosuppression, and prior joint disease. Physical examination should assess for warmth, erythema, swelling, effusion, and limitation of motion, as well as extra-articular features such as rash, cardiac murmurs, or enthesitis. Synovial fluid aspiration and analysis are mandatory in acute monoarthritis or when infection or crystal disease is suspected.
Epidemiology
Septic arthritis is usually monoarticular, with polyarticular involvement occurring in 10–20% of adults. Risk factors include diabetes mellitus, chronic kidney disease, malignancy, immunosuppression, intravenous drug use, trauma, prosthetic joints, and underlying joint disease. Musculoskeletal manifestations occur in up to 45% of patients with infective endocarditis. Viral outbreaks, particularly chikungunya, have caused large numbers of cases of acute febrile polyarthritis, especially among travelers.
Etiology and Pathophysiology
Septic arthritis is the most important diagnosis to exclude and is most commonly caused by Staphylococcus aureus. Other infectious causes include disseminated gonococcal infection, endocarditis, Lyme disease, Whipple’s disease, secondary syphilis, and mycobacterial or fungal infections. Viral etiologies include parvovirus B19, acute HIV infection, hepatitis B, dengue virus, and chikungunya. Noninfectious causes include gout, pseudogout, acute rheumatic fever, adult-onset Still’s disease, systemic lupus erythematosus, vasculitis, and rarely malignancy.
Diagnostic Evaluation
Synovial fluid analysis is central to diagnosis. Bacterial arthritis is suggested by leukocyte counts greater than 50,000 cells/µL with polymorphonuclear predominance, turbid appearance, and low viscosity. Gram stain and culture should always be performed, and blood cultures obtained in acute presentations. Gonococcal arthritis frequently yields negative synovial cultures, requiring sampling of mucosal sites. Elevated ESR and CRP favor bacterial infection, while markedly elevated ferritin levels suggest adult-onset Still’s disease.
Management
Suspected septic arthritis requires immediate empiric antimicrobial therapy after appropriate cultures are obtained. Most cases of nongonococcal septic arthritis require surgical drainage or joint washout. Gonococcal arthritis is usually managed medically with ceftriaxone. NSAIDs provide symptomatic relief in viral and reactive arthritis. Early joint immobilization followed by gradual mobilization is recommended once infection is controlled.
Complications
Delayed or inadequate treatment of septic arthritis may result in irreversible joint destruction, osteomyelitis, bacteremia, and systemic sepsis.
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