Gout, an arthropathy due to monosodium urate crystal deposition, occurs in 0.3% of the population. It occurs 20 times more frequently in men than women. When occurring in women, it demonstrates a post-menopausal predilection.

Primary idiopathic gout is due to any of several inborn errors of metabolism, whereas secondary gout is due to a variety of diseases that cause increased production or decreased excretion of uric acid. Secondary gout usually doesn’t demonstrate radiographic changes. Hyperuricemia is not synonymous with gout, since 2-17% of persons suffer the former, with a minority becoming symptomatic.

Radiographic findings appear in 45% of patients 6-8 years after the initial attack. The urate crystals deposit in poorly vascularized tissues, including cartilage, tendon sheaths, and bursae. Typical features of tophaceous gout include normal mineralization, tophi, joint space preservation, punched-out erosions with sclerotic borders and overhanging cortex, and asymmetrical polyarticular distribution.

Significantly, urate deposition in cartilage produces findings typical of osteoarthritis. Urate crystals are not radiopaque, but calcium may precipitate with the urate, resulting in amorphous increased density in tophi. Tophi are characteristically periarticular and found along the extensor surfaces, though they may be intraarticular or even distant from a joint.

65% of patients experience their first attack in the 1st MTP, and eventually 90% of patients demonstrate involvement at that joint. Asymptomatic periods between attacks last from months to years.