[Clinical characteristics of crystal deposits in joints and tendons in patients with gout].

objectiveTo explore the abnormal manifestations and clinical features of patients with gout according to the location of crystal deposits: in articulars or in tendons.

methodsA total of 105 patients with gout who were continuously treated in the Department of Rheumatology and Immunology of Peking University People's Hospital from June 2019 to December 2019 were selected and their knees, ankles, toes and painful joints and tendons were examined by high-frequency ultrasound. Then we grouped them according to the presence or absence of sodium urate crystals and the location of the crystals, collected their clinical data, and analyzed the clinical characteristics.

resultsAmong the 105 patients, 25 patients had no crystal deposits in the joints or tendons (as the non-crystal group), 43 patients had intra-articular crystals (as the joint group), and 37 patients had intra-tendon crystals with or without intra-articular crystals (as the tendon group). Among them, the most involved part of sodium urate crystals deposited in the joints was the metatarsophalangeal joint (29 cases, 67.4%), followed by knee joints (10 cases, 23.2%), ankle joints (9 cases, 20.9%). The most involved part of sodium urate crystals deposited in the tendon was the quadriceps tendon (16 cases, 43.2%), followed by the Achilles tendon (13 cases, 35.1%), the patellar tendon (12 cases, 32.4%), and the three heads of brachii tendons (5 cases, 13.5%). The three groups were compared using multi-sample analysis of variance/multi-sample rank sum test. Age, age of first increase in uric acid (UA), serum glucose (Glu) level and C reactive protein (CRP) were all significantly different. After multiple comparisons, compared with the non-crystal group, age, the age of first increase in uric acid, and CRP were significantly higher in the tendon group. There was no significant difference between the non-crystal group and the joint group. There was no significant difference between the tendon group and the joint group.

conclusionIn patients with gout, it is common for ultrasound to find crystals deposited in joints or tendons. The most commonly affected parts include the metatarsophalangeal joint, knee joint, ankle joint, quadriceps tendon, Achilles tendon, patellar tendon, and triceps tendon. There were significant differences among the three groups in age, age of first increase in uric acid, CRP and blood glucose, and the proportion of urinary calculi in patients with crystal deposits was significantly higher than those without crystal deposits.