Septic arthritis in ochronosis’ patient

Abstract

Alkaptonuria is a rare autosomal recessive metabolic disease, with an incidence of 1:125,000 to 1:1 million worldwide. First description of Alkaptonuria was done by Garrod in 1908, that also recognized it to follow classic Mendelian recessive inheritance.1 The genetic defect is mapped to the HGD gene and more than 90 different mutations have been identified to date.2 Alkaptonuria is caused by homogentisic acid oxidase enzyme deficiency, that results in high homogentisic acid levels. It will eventually result in black deposits in skin, sclerae, connective tissues and urine. Ochronosis, dark pigmentation of connective tissues, is the musculoskeletal manifestation of this disease.3 It can lead to early degeneration of cartilage, leading to secondary osteoarthritis,4 by a mechanism that has not been understood.2 A worldwide review conducted in 2004 found that approximately 600 cases of ochronotic arthropathy have been reported since 1962.1 The diagnosis is often delayed because of its low prevalence and nonspecific early symptoms.4 The diagnosis occasionally is discovered intraoperatively in patients undergoing joint replacement surgery through the observation of the characteristic bluish-black pigmentation of the tissue surrounding the joint.2 Ochronotic arthropathy manifests first in the spine. Subsequent degeneration is on the knee (most commonly affected, in 64% of cases), hip, and shoulder. Small joints of the hand and foot usually are not affected.2 Homogentisic acid and its oxidation products could accumulate also in the sclera, skin, heart valves, the cartilage of the nose and ears, tendons, ligaments, renal tubule epithelial cells, pancreas, and arteries.5–7 In this paper, it is described a clinical presentation of ochronotic arthropathy with septic arthritis in the knee, of a complex patient.