Knee ochronotic arthropathy and arthroscopic findings

Ochronotic arthropathy is a rare condition found in patients with alkaptonuria which is a hereditary metabolic disease associated with deposition of homogentisic acid derivatives in the articular cartilage, menisci, ligaments, and connective tissues due to homogentisic acid oxidase deficiency. These pigmentary changes are termed ochronosis. We presented a 50-year-old woman in whom arthroscopic examination of the right knee revealed brown-black discoloration of the articular cartilage and menisci leading to the diagnosis of alkaptonuria by further laboratory examinations.