Treatment of Achilles tendon rupture in a patient with alkaptonuric ochronosis

The treatment result of a patient with spontaneous rupture of the Achilles tendon and features of diagnosing alkaptonuric ochronosis, a rare disease, are presented, providing doctors beneficial information for the prevention and/or delay of possible complications. On March 8, 2021, at about 20:50, while at his workplace, getting up from his chair from the table, patient K, 52 years old, felt a sharp pain in the lower third of his right shin and was urgently taken to the hospital. He was examined by a traumatologist and was initially diagnosed with rupture of the right Achilles tendon. His right lower limb was immobilized with a plaster splint. On March 11, 2021, he entered the military traumatology and orthopedics clinic of the Kirov Military Medical Academy for surgical treatment. Upon admission, the patient complained of pain in the right lower leg and impaired support function of the right lower limb. Based on complaints, medical history, laboratory results, and instrumental studies, subcutaneous rupture of the right Achilles tendon was diagnosed. On March 12, 2021, anchor suture of the right Achilles tendon was performed. Anesthesia — combined, access: two separate incisions on the posterior surface of the lower third of the right leg and in the area of the calcaneal tubercle, each 5 cm long, intraoperatively revealed a complete subcutaneous rupture of the right Achilles tendon. Notably, the tendon was black in color when cut. The postoperative period proceeded without complications, and postoperative wounds of linear shape in the right Achilles tendon healed by primary intention. No signs of disturbances were observed in peripheral circulation and innervation of the right lower limb. To confirm the diagnosis, a simple laboratory test was performed: a change in the color of urine during the day, after its additional alkalization. The color change is due to the polymerization of homogentisic acid, which is excreted in large quantities in the urine. To verify the diagnosis, a molecular genetic technique was performed: sequencing of the clinically significant HGD gene and encoding the enzyme homogentisate-1,2-dioxygenase, which are mutations that lead to alkaptonuria. The analysis results confirmed the presence of an amino acid substitution at the pGLy161Arg position, indicating pathogenicity. The use of simple methods of additional laboratory diagnostics and molecular genetic analysis enabled the diagnosis of alkaptonuric ochronosis. Thus, characteristic diagnostic signs were damage to the Achilles tendon in combination with the obtained anamnestic, clinical, and laboratory data of alkaptonuria.