Review Question - QID 203292

The clinical presentation is suspicious of gout. The diagnosis is confirmed by arthocentesis showing intracellular crystals that are thin, needle shaped, and strongly negatively birefringent.

Gout is caused by monosodium urate crystal deposition in tissues leading to arthritis, soft tissue masses (i.e., tophi), nephrolithiasis, and urate nephropathy. Acute gout most often presents as attacks of pain, erythema, and swelling of one or a few joints in the lower extremities. The great toe, or 1st MTP joint is the most common joint involved.

Eggebeen reports gout is caused by monosodium urate crystal deposition in tissues leading to arthritis, soft tissue masses (i.e., tophi), nephrolithiasis, and urate nephropathy. The biologic precursor to gout is elevated serum uric acid levels (i.e., hyperuricemia). Monosodium urate crystals present in synovial fluid confirm the diagnosis.

Weinfeld et al. share their experience over a 7 year period with hallux MTP arthritis in 439 patients they treated. Surgical indications included pain, shoe wear problems, and failure of non-operative management.

Illustration A shows a AP radiograph of the foot demonstrating joint space narrowing of the 1st metatarsalphalangeal joint, medial soft tissue swelling at the 1st MTP, and soft tissue radio-densities consistent with gout. Illustration B shows intracellular crystals that are thin, needle shaped, and strongly negatively birefringent, all consistent with gout.

Incorrect Answers:
Answer 1: While serum uric acid levels are often elevated in gout, it is not specific for the disorder and cannot confirm the diagnosis. Note that serum uric acid levels may be normal during an attack of acute gout.
Answer 2: While radiographs can raise suspicion for gout, there are other conditions that can have similar radiographic findings. Radiographs do not have the specificity to confirm the diagnosis.
Answer 3: While MRI can raise suspicion for gout, there are other conditions that can have similar radiographic findings. MRI does not have the specificity to confirm the diagnosis.
Answer 5: Arthocentesis showing intracellular crystals that are rhomboid-shaped and weakly positive birefringent would confirm the diagnosis of pseudogout, caused by deposition of calcium pyrophosphate dihydrate (CPPD) crystals within the joint space.