Episode 16: Acute Monoarthritis

Acute monoarthritis requires a high index of suspicion for septic arthritis, particularly in patients with pre-existing joint disease, immunosuppression, or compromised skin integrity. While physical examinations and blood work provide baseline data, they lack the sensitivity to definitively rule out infection. Arthrocentesis remains the gold standard for diagnosis; clinicians should avoid relying on rigid synovial fluid white blood cell count cutoffs, as these values often overlap with crystal-induced arthropathies like gout or pseudogout. Management strategies prioritize early identification and intervention to prevent systemic sepsis and permanent joint destruction. For polyarticular presentations, clinicians must evaluate for systemic involvement and consider reactive arthritis or spondyloarthropathies. In cases of suspected gonococcal arthritis, low synovial fluid yield necessitates culturing extra-articular sites—including pharyngeal and rectal swabs—to ensure accurate diagnosis and appropriate antibiotic therapy.