Imaging and image-guided intervention of septic arthritis in adults and children.

Septic arthritis is a critical condition to diagnose as delayed treatment can lead to increased morbidity and mortality. Diagnosis requires a combination of patient history, clinical findings, laboratory results, and supportive imaging findings with potential arthrocentesis. This review summarizes these clinical and laboratory findings as they can be helpful in the interpretation of imaging studies. Typically, a multimodality imaging approach is used to further aid in diagnosis, assess disease extent or complications, and guide aspiration, emphasizing the important role of the musculoskeletal radiologist. Specific imaging modalities and those findings associated with septic arthritis are detailed. Radiographs are readily available and inexpensive but have low sensitivity in early disease. Ultrasound can detect effusions and is the modality of choice to guide most joint aspirations owing to its real-time capabilities and lack of radiation. Computed tomography (CT) plays a major role in the emergency setting due to its wide availability and short scan times, with the ability to evaluate other soft tissue compartments. Magnetic resonance imaging (MRI) remains the most sensitive imaging modality for bone and soft tissue changes as early as the first 24 h. Ultimately, fluid aspiration is the gold standard to diagnose and guide antimicrobial therapy.