[Arthroplasty for the treatment of joint degeneration caused by ochronosis in two cases].

Ochronosis is a rare metabolic disease caused by the deficiency of the homogentisic acid oxidase enzyme. With increasing age, accumulation of pigment deposits of homogentisic acid in the joint cartilage results in ochronotic osteoarthritis. We presented two female patients, with ages 55 and 60 years, who underwent staged bilateral uncemented total hip and bilateral cemented total knee arthroplasty, respectively, for osteoarthritis caused by ochronosis. Both patients had no significant complaints at final follow-up examinations made 12 months and 10 months after the second operation in the hip and knee, respectively. Plain radiographs did not show any abnormality in the components of the prostheses. Histopathologic examination of surgical specimens showed brown-black pigment deposits in the connective tissue and cartilage tissue.