OBJECTIVE Acute and chronic calcium pyrophosphate (CPP) crystal arthritis is characterized by the presence of synovial CPP crystals within a clinically inflamed joint. CPP crystals may be situated intracellularly or extracellularly; however, the clinical significance of their location remains understudied. The objective of this retrospective cohort study was to assess the relevance of the CPP crystal location in diagnosing acute/chronic CPP crystal arthritis. METHODS Data were collected from Waikato District Health Board to identify a study population with synovial fluid samples positive for CPP crystals. The cohort was stratified into 2 groups based on crystal location: intracellular and extracellular. The proportions of acute/chronic CPP crystal arthritis cases were compared between these groups. Acute/chronic CPP crystal arthritis was diagnosed when synovial CPP crystals were present, with objective evidence of joint inflammation and no other alternative diagnosis. Further analysis was made with respect to demographics, other laboratory results, and cartilage calcification. RESULTS This study included 134 patients: 108 with intracellular CPP crystals and 26 with extracellular CPP crystals. Acute/chronic CPP crystal arthritis was diagnosed in 85% of cases in the intracellular and 50% in the extracellular group (P < 0.001). Following exclusion of septic arthritis cases, acute/chronic CPP crystal arthritis was diagnosed in 97% of patients in the intracellular group and in 62% of those in the extracellular group (P < 0.001). CONCLUSION The presence of intracellular CPP crystals is more strongly associated with acute/chronic CPP crystal arthritis than with extracellular CPP crystals alone.

中文翻译：

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细胞内焦磷酸钙晶体与细胞外焦磷酸钙晶体晶体在诊断焦磷酸钙晶体关节炎中的意义。


目的 急性和慢性焦磷酸钙 （CPP） 晶体性关节炎的特征是临床炎症关节内存在滑膜 CPP 晶体。CPP 晶体可能位于细胞内或细胞外;然而，他们位置的临床意义仍然没有得到充分研究。这项回顾性队列研究的目的是评估 CPP 晶体位置在诊断急性/慢性 CPP 晶体性关节炎中的相关性。方法 从怀卡托地区卫生委员会收集数据，以确定滑液样本 CPP 晶体阳性的研究人群。该队列根据晶体位置分为 2 组：细胞内和细胞外。比较这些组之间急性/慢性 CPP 晶体性关节炎病例的比例。当存在滑膜 CPP 晶体时，诊断为急性/慢性 CPP 晶体性关节炎，有关节炎症的客观证据，无其他替代诊断。对人口统计学、其他实验室结果和软骨钙化进行了进一步分析。结果 本研究包括 134 例患者： 108 例细胞内 CPP 晶体，26 例细胞外 CPP 晶体。急性/慢性 CPP 晶体性关节炎在细胞内 85% 的病例中被诊断出来，在细胞外组中被诊断为 50% 的病例 （P < 0.001）。在排除化脓性关节炎病例后，细胞内组 97% 的患者和细胞外组 62% 的患者诊断为急性/慢性 CPP 晶体性关节炎 （P < 0.001）。结论 细胞内 CPP 晶体的存在与急性/慢性 CPP 晶体关节炎的相关性比单独与细胞外 CPP 晶体更强。