The Black Knee – A Case Report

INTRODUCTION: Ochronotic arthropathy in patients with alkaptonuria is a rare hereditary disorder. The altered metabolism causes the homogentesic acid derivatives to deposit in various connective tissues causing characteristic pigmentation. Due to the close clinical resemblance to that of a degenerative disorder, diagnosis of ochronotic arthropathy usually occurs intraoperatively. We report arthroscopic findings of a 50-year-old female with ochronotic arthropathy. CASE REPORT: A 50-year-old woman came with complaints of pain and swelling in the left knee. Clinical examination and MRI findings were correlated to reveal a tear of lateral meniscus. On arthroscopic examination, the blackish pigmentation of the meniscus and the articular cartilage led to the diagnosis of ochronotic arthropathy. CONCLUSION: Arthroscopy plays an important role in diagnosis and treatment of patients with ochronotic arthropathy. The characteristic arthroscopic finding may aid diagnosis even in patients who do not have other systemic manifestations. Timely arthroscopic intervention can help delay the disease progression.