A 72-year-old man injures his right knee in a car accident, and now it is swollen and extremely painful to bend the knee. X-rays of the knee rule out a fracture, and joint fluid aspiration reveals an opaque-colored fluid containing rhomboid crystals with weak-positive birefringence. Which of the following is the most appropriate next step in management?

In traumatic arthritis, swellings, ecchymoses, muscular spasms, and tenderness tend to be present, but fractures must be excluded. This man has calcium pyrophosphate (CPPD) crystal-induced monoarthritis, so called "pseudogout." It is most common in the elderly and can be precipitated by minor trauma. The crystals have a rhomboid shape, and the clinical presentation can mimic that of gout. It can be associated with metabolic abnormalities such as hyperparathyroidism or hemochromatosis. Treatment is with an NSAID for 7-10 days. If there are multiple joints involved, then steroids can be considered. An alternative to oral NSAIDs is intra-articular steroids for single joint disease. Allopurinol is not effective in CPPD. Synovial fluid is bloody, but the fluid is of normal viscosity, so a "string" test is usually positive.