Articular cartilage of knee and first MTP joint are the preferred sites to find double contour sign as an evidence of urate crystal deposition in asymptomatic hyperuricemic individuals

Background/Objective: A cross-sectional study to determine the preferred sites of urate crystal deposition in asymptomatic hyperuricemic individuals by ultrasound. Methods: In two years period twenty four asymptomatic hyperuricemic individuals (serum uric acid ≥7mg/dl) and fifty controls (serum uric acid <7mg/dl) with age more than 18 years were included in this study. Double contour sign was looked for at three articular cartilage sites (first metatarsophalangeal, tibiotalar and femoral condyle) whereas hyperechoic aggregates were looked for at one joint site (radiocarpal joint) and two tendon sites (patellar tendon and triceps tendon). The Chi-square test was used to compare the categorical variables and discrete variables were compared by one way analysis of variance. The p-value<0.05 was considered significant. Results: Eight out of 24 asymptomatic hyperuricemic individuals had ultrasound evidence of urate crystal deposition in first metatarsophalangeal joint area followed by knee joint area which was detected in 6 patients. The detection rate of ultrasound abnormalities in asymptomatic hyperuricemic individuals was 45.8% with two joint area (knee and first metatarsophalangeal) and 50% with six sites assessment. Amongst controls, 16% were found to have these abnormal ultrasound findings. Conclusion: The highest predilection of urate crystal deposition in asymptomatic hyperuricemic individuals is the articular cartilage of Knee and first metatarsophalangeal joints. This explain the frequent clinical presentation of arthritis in these joint areas.