Ochronotic Arthropathy with Severe Articular Involvement Necessitates Total Joint Replacement

Abstract

The aim of this paper is to describe the pathological and clinical features of alkaptonuria (AKU). AKU clinical presentation is identified as ochronosis, the dark pigmentation of skin and cartilage that is caused by progressive accumulation of homogentisic acid (HGA) in connective tissues. We also discuss surgical considerations about joint replacement, which represents the only treatment in the case of severe articular degeneration. We report the case of a middle-aged female with both hip and knees affected. She underwent bilateral hip replacement and right knee arthroplasty. Preoperatively, the patient was examined clinically. Harris Hip Score (HHS) and Hospital for Special Surgery score (HSS) were completed for both hips, and for the right knee. Radiographs were made of both hips and the knee, in different projections. HHS for the left and right sides at the latest follow-up (11 and 9 years after surgery respectively) were 98 and 95. HSS 3.5 years after surgery was 97. Alkaptonuria is a rare inherited pathology caused by deficiency of the enzyme homogentisic acid oxidase (HGAO). Skeletal involvement is frequent and causes severe cartilage damage. HGA levels in blood and urine and articular symptoms make the diagnosis certain. Therapy is still debated: diet offers good results in young people while high doses of C vitamin seem to reduce the amount of deposits. Articular localizations usually lead to joint replacement. In this case functional and radiographic results are excellent even at long follow-up.