Ochronotic arthritis of bilateral knees: a case report.

Alkaptonuria ochronosis is a rare metabolic disease in which the body does not have enough enzyme called homogentisic acid oxidase. Due to the homogentisic acid oxidase deficiency, homogentisic acid accumulates in cartilage and connective tissues which leads to ochronotic arthritis. We reported a case of bilateral ochronotic arthritis verified by clinical presentation, imaging, arthroscopic and histological findings. The patient achieved a satisfying therapeutic outcome after arthroscopic debridement followed by intra-articular injection of sodium haluronate.