Severe Osteoarthritis of the Knee as an Early Symptom of Alkaptonuria: A Case Report

Alkaptonuria (AKU) is a very rare disease and occurs due to the deficiency of the enzyme homogentisate1, 2-dioxygenase (HGD) which results in ochronosis, a term used to describe the dark pigmentation of the tissues. Alkaptonuria affects mostly the knee joint followed by the hip as major weight bearing joints, where the life quality of such patients is severely affected. Case Presentation: We present a case of Caucasian male who was suffering from severe osteoarthritis of the knee. Initially he underwent an arthroscopic partial meniscectomy in a nearby hospital. Fourteen months later we performed a total knee replacement using the Journey II CR prosthesis. We found a dark pigmentation of the inside of the knee (synovial tissue and cartilage). A positive urine test and a pathological specimen examination revealed the diagnosis of AKU. The patient had no complications after the surgery and underwent a standard rehabilitation program. Conclusions: Osteoarthritis could be the first manifestation of patients with AKU and the onset of the joint disease could be late and rapid.