Gout - crystal deposition hyaline cartilage

note: patient with recurrent episodes of gouty arthritis of the knee (synovial fluid analysis with urate crystals). The ultrasound reveals irregular hyperechoic enhancement of the superficial margin of the hyaline cartilage (urate deposits) - not the cartilage interface sign (this arises due to the marked difference in acoustic impedances of the two tissues at the interface as a thin, regular hyperechoic line when the sound beam is perpendicular to the cartilage)