Alkaptonuria is an autosomal recessive metabolic disorder characterized by joints and spine involvement, ochronosis and presence of homogentisic acid (HGA) in urine and its deposition in cartilage, and other connective tissues, leading to disabling arthritis in elderly individual (5). It affects one in 100,000 to 250,000 individuals
1,2. It is caused by the lack of HGO enzyme deficiency due to an autosomal recessive mutation of the HGO gene on chromosome 3 which plays a role in the metabolism of tyrosine and phenylalanine. The defective enzyme leads to an accumulation of HGA in tissues and blood over the years, and polymers of HGA are deposited in the tissues, causing the dark pigmentation encountered in these patients
6,7. The first finding is a colour change in the urine
4. Ochronotic arthropathy is seen most between the ages of 40-60 years and in weight-bearing joints which is a particularly troublesome feature
8. Typically, involvement of the large peripheral joints occurs several years after spinal involvement
9. Usually, involvement of these joints is severe and often requires joint replacement
4,9 .
In the current case who was aged 63 years, there was right hip joint involvement. Apart from colour changes associated with joint involvement, the characteristics resemble primary osteoarthritis 10. The intraoperative visualisation of the blue-black colour change in the joint tissue of the current case is typical.
In the literature the treatment regimes were described due to the complaints of degeneration of especially hip and knee joints 11,12. In the late stages of arthritis, orthopedic surgery is prominent. In our case, hip arthroplasty were performed after the failure of conservative treatment modalities. We could obtain extremely good results with arthroplasty after 5 year follow up.
Arthroplasty is effective for treating severe arthritis of the knee ascribable to ochronosis. We report an excellent outcome with total hip replacement in a patient with significant degenerative arthritis secondary to ochronotic arthritis. Alkaptonuria is an inherited disease which can lead to severe consequences. Early diagnosis and new treatments can enhance the quality of life of patients suffering from this disease.