The sudden onset and severity of monoaicular ahritis suggests acute gouty ahritis, especially in patient on diuretic therapy. Ahrocentesis is indicated in the first episode- demonstrate needle shaped, negatively birefringent crystals and to rule out other diagnoses such as infection. For most patients with acute gout, NSAIDs are the treatment of choice. Colchicine is also effective, but causes nausea and diarrhea. Antibiotics should not be staed for infectious ahritis before an ahrocentesis is performed. Hyperuricemia should never be treated in the setting of an acute attack of gouty ahritis. Long-term prophylaxis with allopurinol is considered for repeated attacks of acute ahritis, or formation of tophaceous deposits. X-ray of the ankle would likely be inconclusive in this patient with no trauma history