What diagnostic studies are useful in the initial evaluation of monoarticular arthritis?
• Radiograph of the joint: Although frequently normal, the radiograph may disclose important information. It may diagnose unsuspected fracture, osteonecrosis, osteoarthritis, or juxtaarticular bone tumor. The presence of chondrocalcinosis, a radiologic feature of calcium pyrophosphate dihydrate deposition (CPPD) disease, increases suspicion for a pseudogout attack. Tumor, chronic fungal or mycobacterial infection, and other indolent destructive processes may be revealed. Contralateral joint radiograph for comparison may be useful, especially in children.
• Complete blood count: Leukocytosis supports the possibility of infection.
