Ochronosis and joint destruction are caused by accumulation of homogentisic acid in connective tissues1. Few cases have been reported of patients with severe ochronotic arthroplasty and need of surgical reconstruction with arthroplasty2,3,4.
An 80-year-old white woman of Austrian descent presented at our outpatient clinic complaining of year-long pain and reduced range of motion in the right hip joint. Clinical and radiological examination showed severe osteoarthritis of the hip joint. Surgical reconstruction with primary total hip arthroplasty (THA) was indicated. Capsulotomy revealed dark brownish pigmentation of the cartilage of the hip joint.
Histology of intracapsular tissue performed intraoperatively showed no signs of local infection. The femoral neck was osteotomized (Figure 1) and THA was performed successfully. Postoperative clinical examination showed hyperpigmentation of the sclerae (Figure 2) and ear cartilage. Family history revealed that her late brother had also had hyperpigmentation of the sclerae and ear cartilage. Alkaptonuria was diagnosed in the urine sample by mass spectroscopy, which showed increased levels of homogentisic acid.
The patient was discharged in healthy condition with full weight-bearing capability and an increased range of motion of the hip joint.
Alkaptonuria is a rare autosomal recessive disorder causing a deficiency of the homogentisic acid-oxidase enzyme5. Thus increased levels of homogentisic acid, a tyrosine-degradation product, can be found in urine. Ochronosis and joint destruction are caused by the accumulation of homogentisic acid in connective tissues1.