Background/Purpose: The prevalence of hyperuricemia ranges from 2.6% to 47.2% in various populations [1,2]. Ultrasound evidence of urate crystal deposition in the form of double contour sign (DCS) and hyperechoic aggregates (HAGs) in asymptomatic hyperuricemic (AH) individuals has been documented in studies [3]. It has been reported that assessment of one joint (ie, radiocarpal) and two tendons (ie, patellar and triceps) for HAGs, and three articular cartilages (ie, first metatarsal (1^st MTP), talar and second metacarpal/femoral) for DCS showed the best balance between sensitivity and specificity (84.6% and 83.3%, respectively) in diagnosing intercritical gout[4]. So we aimed to find the preferred sites of urate crystal deposition among these six sites in AH individuals.

Methods: 24 AH (serum uric acid (SUA) ³7mg/dl) and fifty controls (SUA <7mg/dl) with age more than 18 years were included in this study. DCS was looked for at three articular cartilage sites (1^st MTP, tibiotalar and femoral condyle) whereas HAGs were looked for at one joint site (radiocarpal joint) and two tendon sites (patellar tendon and triceps tendon). Ultrasound was done using multifrequency linear array transducer (8–13 MHz) of Logiq E; GE Medical Systems Ultrasound, on B mode gray scale (GS). Settings of machine were as follows: dynamic range of 40–50 dB, GS frequency of 11–13 MHz and GS gain of 60 dB.

Results: 8 out of 24 AH patients had ultrasound evidence of urate crystal deposition in 1^st MTP joint area followed by knee joint area which was detected in 6 patients. The detection rate of ultrasound abnormalities in AH was 45.8% with two joint area (knee and 1^st MTP) and 50% with six sites assessment. Amongst controls, 16% were found to have these abnormal ultrasound findings by both two joint area and six sites exams. (Figure: DCS at knee and 1^st MTP joint)

Conclusion: The highest predilection of urate crystal deposition in AH patients is the articular cartilage of Knee and 1^st MTP joints.

References:

1.     Currie W: Prevalence and incidence of the diagnosis of gout in Great Britain, Ann Rheum Dis 38:101, 1979.

2.     Klemp P, Stansfield S, Castle B, Robertson M: Gout is on the increase in New Zealand, Ann Rheum Dis 56:22, 1997.

3.     Pineda C, Amezcua-Guerra LM, Solano C,  Rodriguez–Henr’quez P, Hern‡ndez-D’az C, Vargas A, et al. Joint and tendon subclinical involvement suggestive of gouty arthritis in asymptomatic hyperuricemia: an ultrasound controlled study. Arthritis Res Ther 2011;13:R4.

4.     Naredo E, Uson J, JimŽnez-Palop M, Mart’nez A, Vicente E, Brito E, et al. Ultrasound-detected musculoskeletal urate crystal deposition: which joints and what findings should be assessed for diagnosing gout? Ann Rheum Dis 2014;73: 1522–1528.