Background/Purpose:

Although considered as uncommon, the hip represents one of the possible targets of gout. To date, hip involvement in patients with gout has been poorly investigated by clinical and/or imaging studies. To the best of our knowledge, this is the first study aimed at assessing the prevalence of monosodium urate (MSU) crystal deposits at the hip in patients with gout. The objective of this study is to investigate the prevalence of the US findings indicative of MSU crystal deposits at the hip in consecutive patients with gout, diagnosed according to the 2015 ACR/EULAR classification criteria.

Methods:

Inclusion criteria: synovial fluid analysis positive for MSU crystals or presence of subcutaneous tophi at the physical examination.

Exclusion criteria: prior diagnosis of others crystal related arthropathies, such as CPPD or calcium basic phosphate crystal arthritis, highly suggestive findings of CPPD detected at the knee US exam, previous surgical procedures and/or remarkable injures of the hip. Each patient underwent a bilateral hip and knee US exam. The US exam was carried out using a My Lab Twice US machine (Esaote S.p.A. Genoa, Italy), working with a linear (3-13 MHz) or, when necessary, a convex probe (2-7 MHz). The US abnormalities indicative of MSU crystals deposition were identified according to the OMERACT definitions. At the hip, the following abnormalities were investigated: intra-articular tophi and/or aggregates, double contour (DC) sign over the hyaline cartilage of the femoral head.

Results:

Seventy hips, in 35 patients with gout [age (mean±standard deviation) 69.1±11.2; female/male 1/34, disease duration 10.3±10.8 years], were evaluated. The US examination revealed the presence of one or more US findings indicative of MSU crystal deposits in at least one hip in 15 out of 35 patients (42.8%), in 19 out of the 70 hips (27.1%). Tophi were found in at least one hip in 5 out of 35 patients (14.2%), in 6 of the 70 hips (8.5%). Aggregates were detected in at least one hip in 12 out of 35 patients (34.2%), in 12 out of the 70 hips (17.1%). DC sign was found in at least one hip in 5 out of 35 patients (14.2%), in 6 out of the 70 hips (8.5%). Twenty-eight patients were assessed using a linear probe (3-13 MHz) and the remaining 7 patients were studied using a convex probe (2-7 MHz). Figure 1 shows the US findings indicative of MSU crystal deposits at the hip.

Conclusion:

These preliminary results show that the prevalence of hip involvement in patients with gout might be underestimated. Further investigations in a larger cohort of patients are needed to explore the clinical and laboratory features associated with hip involvement in patients with gout.

Reference

• Huet T, et al. Hip Gout Arthritis Revealed by Sonography. J Ultrasound Med 2016 Aug;35(8):1828-9

Figure 1. Legend. A: intra-articular tophus (curved arrow). B: intra-capsular aggregate (white arrow). C: double contour over the hyaline cartilage of the femoral head (arrowheads).

« Back to 2018 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/hip-involvement-in-patients-with-gout-results-of-an-ultrasound-study/