Ochronosis, arthroscopy of a black knee: a case report and review of the literature.

Ochronotic arthropathy is a rare condition found in patients with alkaptonuria. Due to the accumulation of homogentisic acid, cartilages get a dark discoloration and become brittle and more vulnerable to mechanical stress (Centinus et al. Rheumatol Int 3:127-131, 2004; Hamdi et al. Int Orthop 23:122-125, 1999; Phornphutkul, N Engl J Med 347:2111-2121, 2002; Thacker, Arthroscopy 19:14-17, 2003). This case report is about a patient first diagnosed for ochronosis by arthroscopy of the knee. Her brother was having similar complaints during follow-up. Both patients were prescribed to take glucosamine and chondroitine. Although no report is found in the literature, regarding the success of this therapy in patients with ochronosis, both patients reported a positive effect on articular pain and daily activities.