大部份慢性关节炎的病因不明。聚合酶链反应（PCR）有可能用来研究滑液及组织中的微生物，因微生物量可能很少或处于不能培养状态，而PCR具高度敏感性及特异性。早期曾对反应性关节炎及Lylne病关节炎作过研究。微生物在病变部位的启动作用已不容怀疑。但不清楚的是是否有完整微 The etiology of most chronic arthritis is unknown. Polymerase chain reaction (PCR) may be used to study microorganisms in synovial fluid and tissues, which may be minimal or inaccessible, while PCR is highly sensitive and specific. Early reactive arthritis and Lylne arthritis have been studied. The role of microorganisms in the activation of lesions has been beyond doubt. But it is not clear if there is complete micro