A 74-year-old male with alkaptonuria (AKU) was admitted to the emergency department left distal femur pain and Rorabeck type 2 periprosthetic fracture following total knee arthroplasty (TKA). AKU is an autosomal recessive disorder characterized by homogentisic acid buildup in connective tissues joints, leading ochronosis arthritis. Multiple joint replacements are common patients, fractures may ...

Alkaptonuria is a rare inherited genetic disorder of tyrosine metabolism that causes the urine to turn black on contact with the air when homogentisic acid is oxidized to form a pigment-like polymer material [1,2]. The earliest sign of the disorder is the tendency for babies’ diapers to stain black; later on in childhood and early adulthood, there is an asymptomatic, progressive deposition of t...