1. The patient presented with swelling and pain in the knee joint, which was diagnosed as hydrarthrosis.
患者出现膝关节肿胀和疼痛，被诊断为关节积水。

2. Hydrarthrosis can be caused by trauma, infection, or underlying joint diseases.
关节积水可以由外伤、感染或潜在的关节疾病引起。