目的: 通过超声检查的方法,分析痛风关节炎患者下肢关节以及肌腱的异常表现,探讨在肌腱部位通过超声检测发现尿酸钠 (monosodium urate, MSU)晶体沉积的危险因素,并探讨其在痛风患者诊断中的应用价值。方法: 选择2017年1月至2019年1月在北京大学第一医院风湿免疫科门诊连续就诊并资料完整的痛风患者共80例作为病例组,选择同期北京大学第一医院体检人群中年龄匹配的健康志愿者80例作为对照组进行回顾性分析,由超声医生对双侧跟腱、髌腱、股四头肌腱进行检查,超声医生不知晓患者的临床诊断。超声检查根据患者是否出现肌腱尿酸钠晶体沉积,对患者进行分组比较,探讨相关的危险因素。以偏振光显微镜下在关节滑液或痛风石中发现尿酸钠晶体做为金标准,计算患者是否出现肌腱尿酸钠晶体沉积对于痛风诊断的敏感性和特异性。结果: 病例组共80例患者,临床查体发现33例(47.5%)存在痛风石。超声肌腱内出现MSU晶体沉积,按照出现的频率从高到低依次为跟腱、股四头肌腱、髌腱,例数分别为41例(51.2%)、22例(27.5%)、10例(12.5%),健康志愿者均未发现痛风石以及肌腱受累表现。与肌腱内未见MSU晶体组患者相比较,肌腱内MSU晶体阳性组患者的痛风平均病程更长[(87.3±40.9)个月vs.(7.7±2.6)个月, P=0.001], 平均痛风每年的发作频率更高[2(1,2) 次/年 vs. 1(1,1)次/年,P=0.001],体重指数(body mass index,BMI)更高[(26.3±2.5) kg/m²和(23.3±2.1) kg/m², P=0.05]。肌腱内MSU晶体阳性组的痛风患者平均血清尿酸水平和平均血清肌酐水平明显高于肌腱内未见MSU晶体沉积者[(584.6±87.6) μmol/L vs. (460.4±96.7) μmol/L,P=0.001;(90.9±33.3) μmol/L vs.(70.6±40.2) μmol/L,P=0.02]。Logistic回归分析显示,既往病程、既往痛风发作频率均为痛风患者肌腱内出现MSU晶体沉积的独立危险因素(P<0.01)。所有痛风患者均进行关节腔或痛风石穿刺术,以偏振光显微镜下找到MSU晶体为诊断痛风的金标准,超声检测肌腱内出现MSU沉积的敏感性以及特异性分别为94.0%和78.0%。结论: 通过超声检查,痛风患者下肢肌腱受累很常见,既往病程及发作频率是肌腱内出现晶体沉积的危险因素。超声对于探测肌腱内的痛风石以及聚集物有较好的敏感性和特异性。

Objective: To evaluate frequency and patterns, risk factors of MSU (monosodium urate) crystal deposition at lower extremity tendon by ultrasonography in gout patients, and to explore diagnostic value by ultrasonography.Methods: Patients diagnosed with gout and age matched healthy controls had ultrasound scanning of both feet and knees including joints and tendons (achilles, quadriceps, and patellar tendon). Readers who scored the ultrasound scans for MSU crystal deposition were blinded to the patients’ clinical diagnoses. Clinical characteristics were compared between positive and negative crystal deposition groups by US, and risk factors of MSU deposition in tendons were analyzed. Diagnostic values of MSU deposition were evaluated by ultrasonography according with positive MSU crystal in synovial fluid or tophi by polarized microscopy.Results: Eighty patients and eighty healthy controls were included. Thity-three patients (47.5%) had tophi by physical examination. The achilles tendon was the most commonly involved tendon site 41(51.2%), followed by the quadriceps tendons 22(27.5%), and patella tendon 10(12.5%). There were no MSU deposition in healthy control group at tendon by ultrasonography. Compared with negative MSU deposition at tendon site by ultrasonography, tendon MSU positive patients had longer mean gout duration [(87.3±40.9) months vs. (7.7±2.6) months, P=0.001];higher frequency of gout flare [2(1, 2) /year vs. 1(1,1) /year, P=0.001]; higher BMI [(26.3±2.5) kg/m²vs. (23.3±2.1) kg/m², P=0.05]. Also, the mean serum uric acid and creatinine levels were higher in tendon MSU positive group [(584.6±87.6) μmol/L vs. (460.4±96.7) μmol/L, P=0.001] and [(90.9±33.3) μmol/L vs. (70.6±40.2) μmol/L, P=0.02] separately. Logistic regression analysis showed gout duration and flare frequency were independent risk factors for MSU deposition at tendon by ultrasonography (P<0.01). Joint or tophi aspirations were performed in all the eighty gout patients, and positive MSU crystals in synovial fluid analysis by polarized microscopy were defined as the golden standard of gout diagnosis. When compared with the golden standard, the sensitivity and specificity were 94.0% and 78.0% separately for MSU deposition at tendon by ultrasonography. Conclusion: Tendon involvement at the lower extremity tendons in gout is very common. Long gout disease duration and high frequency of gout flare are both independent risk factors of tendon MSU deposition by ultrasonography. Ultrasonography had good sensitivity and specificity for detecting tendinous tophi and aggregates.