Total hip arthroplasty in patients with alkaptonuria: a case report

Alkaptonuria (AKU) is a rare autosomal recessive disorder caused by mutations in the homogentisate 1,2-dioxygenase (HGD) gene, often leading to debilitating ochronotic arthropathy that requires total joint arthroplasty (THA). This case report describes a 56-year-old male patient with AKU who underwent THA due to end-stage arthropathy. Genetic testing revealed that the subject carried a c.157C > T (p.Arg53Trp) variant, a missense variant in the coding region of the HGD gene, and a c.880-9T > A variant, a single base substitution in the intronic region of the HGD gene. Both were classified as variants of uncertain significance (VUS). The preoperative Visual Analog Scale (VAS) score was 4, which decreased to 2 by postoperative day 5 and reached 0 at the 1-month follow-up. At six months postoperatively, the patient reported no pain, free hip range of motion, and high satisfaction. For patients with ochronotic end-stage arthropathy, arthroplasty can achieve favorable early clinical outcomes, although longer follow-up is needed.