Harris David J, White Douglas H N, Arad Uri M
D.J. Harris, MBChB, Health New Zealand Waitemata District, Auckland;
D.H.N. White, MBChB, U.M. Arad, MD, PhD, Health New Zealand Waikato District, Hamilton, and Waikato Clinical School, University of Auckland, Hamilton, New Zealand.
J Rheumatol. 2025 Jan 1;52(1):87-92. doi: 10.3899/jrheum.2024-0469.
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.
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.
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 ( < 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 ( < 0.001).
The presence of intracellular CPP crystals is more strongly associated with acute/chronic CPP crystal arthritis than with extracellular CPP crystals alone.
急性和慢性焦磷酸钙（CPP）晶体关节炎的特征是在临床发炎的关节内存在滑膜CPP晶体。CPP晶体可能位于细胞内或细胞外；然而，其位置的临床意义仍未得到充分研究。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晶体关节炎中的相关性。
从怀卡托地区卫生局收集数据，以确定滑膜液样本中CPP晶体呈阳性的研究人群。根据晶体位置将队列分为两组：细胞内和细胞外。比较这些组之间急性/慢性CPP晶体关节炎病例的比例。当存在滑膜CPP晶体、有客观的关节炎症证据且无其他替代诊断时，诊断为急性/慢性CPP晶体关节炎。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。
本研究纳入134例患者：108例细胞内有CPP晶体，26例细胞外有CPP晶体。细胞内组85%的病例诊断为急性/慢性CPP晶体关节炎，细胞外组为50%（<0.001）。排除化脓性关节炎病例后，细胞内组97%的患者诊断为急性/慢性CPP晶体关节炎，细胞外组为62%（<0.001）。
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的细胞外CPP晶体更强。
