[Beware of misdiagnosis and incorrect treatment of acute gout flare and postoperative infections after arthroscopic surgery for knee gouty arthritis].

Objective: To analyze the differences of clinical features of acute gout flare and postoperative infection under arthroscopy of knee gouty arthritis patients to offer guiding opinions of clinical diagnosis and treatment.

Methods: Between January 2017 and December 2022, 235 patients with gouty knee osteoarthritis were admitted, and underwent arthroscopic debridement combined with synovectomy. Among them, 35 cases had fever with a temperature higher than 38 °C postoperatively while acute inflammatory appears under redness, swelling, heat and pain of the operated joints. There were 29 males and 6 females, with an average age of (41.48±13.90) years old. Among them 23 patients were diagnosed with acute gout attack, and recovered well after being given colchicine and prednisolone;12 patients were diagnosed with postoperative joint infection, and were cured after being given anti-infective treatments and cleaning and rinsing of the joint cavity. The two groups of patients were compared and analyzed in terms of preoperative general data, surgical conditions, hematology, joint fluid, limb function and other clinical characteristics.

Results: There were no significant difference in the preoperative general data between two groups. The onset of fever in the postoperative acute gout flare group occurred mostly within 48 hours, significantly earlier than that in the postoperative infection group(=0.037). The visual analogue scale score was significantly higher in the acute gout flare group (5.32±1.38) score than in the postoperative infection group (2.45±0.68) score (=0.000), while 14 patients with acute gout flare were accompanied by severe pain in other joints. Hematologically, indicators such as white blood cell counts and ratios were significantly higher in both groups. In terms of inflammatory indicators, IL-6, erythrocyte sedimentation rate, procalcitonin and other inflammatory indicators were significantly elevated in both groups, but there was no statistical difference between two groups. The C-reactive protein level in the postoperative infection group (220.97±116.30) mg·L was higher than that in the postoperative acute gout attack group(120.67±82.45) mg·L(=0.006). Blood uric acid (316.55±112.84) μmol·L was higher in the acute postoperative gout flare group than in the postoperative infection group (159.14±126.92) μmol·L(=0.001). In the joint fluid examination of the postoperative infection group, the glucose metabolism indicator was significantly lower than that of the acute gout flare group, and five of them had positive bacterial cultures.

Conclusion: The symptoms of acute gout flare could be mistaken as postoperative infection due to their similarity, therefore requires careful differentiation. Differential diagnosis should be based on a combination of clinical signs, hematology and joint fluid findings, and targeted treatment should be given to avoid serious complications.