前十字韌帶痛風石沉積造成膝關節僵鎖

Anterior Cruciate Ligament and Synovial Tophi Deposition Causing Knee Locking

膝關節鎖定合併伸直不能之現象常起因於半月板提把形破裂造成的夾擊現象。在較少見的狀況，前十字韌帶斷裂造成的斷片夾擊及後十字韌帶斷裂的夾擊也會造成膝關節機械性僵直伸直不能的現象。痛風為常見的新陳代謝疾病，常造成尿酸結晶堆積於膝關節、踝關節及大腳趾關節引起紅腫熱痛現象尤其在急性痛風發作期間。慢性痛風石沉積可能造成硬骨及軟骨侵蝕及破壞關節。膝關節鎖定及伸直不能之現象為痛風石沉積少見的症狀，本個案報告在此提出以供鑑別診斷。

Knee locking is a condition in which the knee cannot be extended completely, primarily because of intraarticular mechanical blockage. The most common cause of blockage is meniscal lesions, particularly, the bucket-handle lesion.[1] Gouty arthritis is a metabolic disorder characterized by elevated urate and urate monohydrate crystal deposition in the serum. The crystals are responsible for causing a hot and swollen knee during an acute gouty attack. We report a case of gouty arthritis of the knee in which tophi deposition over ACL caused mechanical knee blockage. In the case of progressive knee locking with a history of gouty arthritis, MRI may be helpful to rule out other knee-locking factors, such as meniscal and ACL. However, direct visualization of the intraarticular anatomy of the organ may be more direct in ruling out and treating the underlying causes of mechanical blockage.