Explanation

This patient presents with monoarticular arthritis and a synovial fluid sample consistent with gout. Gout is a systemic disorder that manifests with joint inflammation. It is caused by precipitation of uric acid crystals from extracellular fluid. Hyperuricemia results either from underexcretion of end products of purine metabolism from the kidney or overproduction (more rare). During an episode of gout, polymorphonuclear cells ingest the crystals and release cytokines, leading to an inflammatory reaction within the synovium. The most commonly affected joint is the first metatarsophalangeal (MTP) joint, followed by the knee. It is important to consider that patients with gout are at a higher risk of developing septic arthritis because the joints are chronically damaged. In patients with a history of gout who present with symptoms concerning for septic arthritis (pain, fever, decreased range of motion), arthrocentesis should be performed to rule out the presence of infection. Management of gout should be split into acute gouty attack treatment and long-term prophylaxis. The mainstay of acute therapy is NSAIDs and colchicine. Indomethacin, naproxen, and ibuprofen all may be used in acute treatment. Colchicine inhibits microtubule formation, reducing the inflammatory response to uric acid crystals. Unfortunately, the drug has a number of side effects that are almost universally experienced at therapeutic doses (nausea, vomiting, diarrhea).