Figure. Anteroposterior radiograph of the first toe.
A 57-year-old man presents to the office with a 1-day history of severe pain in his first toe. He denies an injury or precipitating event that may have caused the pain, but he reports experiencing a similar episode of pain last year that was treated successfully with an oral steroid taper. Anteroposterior radiograph of the toe is obtained (Figure) and shows osteoarthritic changes and soft tissue swelling of the metatarsophalangeal (MTP) joint. Physical examination reveals an erythematous, swollen MTP joint.
Submit your diagnosis to see full explanation.
Gout is an acute inflammatory arthritis caused by the deposit of monosodium urate (MSU) crystals in the joint space. The primary risk factor for developing gout is a uric acid level >6.9 mg/dL or hyperuricemia.1
Certain food and beverages can contribute to the development of hyperuricemia: these include red meat, alcohol, beverages containing high-fructose corn syrup, and seafood. Consumption of these products may increase levels of serum and synovial fluid urate that precipitate the deposition of MSU crystals on synovial tissue and articular cartilage. Crystal deposition triggers an inflammatory response that causes acute joint pain. Gouty arthritis most commonly affects the foot, specifically the first MTP joint.2
MSU crystal deposition has a higher affinity for joints affected by osteoarthritis, which is common at the MTP joint. The definitive diagnosis of gout is made by the presence of MSU crystals on synovial fluid analysis. However, joint aspiration is not practical for the diagnosis of gout of the big toe. Serum uric acid levels, diet history, and previous symptomatology help make the diagnosis.1,2
Serum uric acid levels, however, may not be elevated during an acute attack of gout. In up to 14% of patients, serum uric acid levels may be <6 mg/dL during an acute gout attack, and only 20% of patients with hyperuricemia will have a gout attack.1
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
1. Meller M, Epstein A, Meller AY, et al. Hyperuricemia and gout in orthopaedics. JBJS Rev. 2018;6(10):e11.
2. Roddy E. Revisiting the pathogenesis of podagra: why does gout target the foot?J Foot Ankle Res. 2011;4(1):13.