Background In addition to acute attacks of severe joint pain and swelling, chronic gout has been associated with weaker foot/leg muscles, altered gait patterns and on-going foot pain. Inflammation associated with gout may change tissue elasticity and ultrasound imaging (US) utilising elastography is a non-invasive method of quantifying these changes in tendon stiffness and elastography findings have not previously been reported in individuals with gout.
Objectives To determine differences in Achilles tendon stiffness in people with chronic gout compared to controls (non gout)
Methods A cross sectional study comparing people with gout according to 2015 ACR/EULAR criteria and age/sex matched controls. Clinical and demographic data were collated and US imaging used to determine tendon thickness, presence of gouty tophi and/or aggregates and levels of angiogenesis. Previously validated protocols for conventional US imaging  and shear wave elastography  were used. Prior to data collection, intra-observer error was good (ICC (2) 0.69 (95%CI 0.62-0.89)). Ten elastography measures were taken along a longitudinal section of the mid-point of the Achilles tendon bilaterally. Data were summarised using descriptive statistics and a repeated measures ANCOVA was used to compare elastography outcomes between the two groups for the left and right foot separately after accounting for Body Mass Index (BMI).
Results A total of 14 people with gout and 13 age/sex matched control subjects participated. Table 1 displays clinical and demographic data. A small proportion of those with gout presented with intra-tendon aggregates and/or intra-tendon tophi in one or both tendons n=7 (27%) for both). There was no significant difference in tendon thickness between groups, neo-vascularity was present in n=3 (21%) gout participants. Elastography findings (table 2) demonstrated significantly reduced tendon stiffness in those with gout compared to controls.
Conclusion Subjects with chronic gout show reduced Achilles tendon stiffness compared to controls. From a clinical standpoint, our findings were similar to elastography measurements in otherwise healthy subjects with Achilles tendinopathy and who did not have gout .
References  Carroll M, Dalbeth N, Allen B, et al. Ultrasound Characteristics of the Achilles Tendon in Tophaceous Gout: A Comparison with Age- and Sex-matched Controls. J Rheumatol. 2017 44(10):1487-1492.
 Payne C, Watt P, Cercignani M, Webborn N. Reproducibility of shear wave elastography measures of the Achilles tendon. Skeletal Radiol. 2017 17 2846-8.
 Payne C 2018 Clinical Applications of shear wave elastography to Achilles tendon imaging and monitoring of a rehabilitation protocol for Achilles tendonopathy PhD Thesis, University of Brighton
Disclosure of Interests None declared
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