Total Shoulder Reverse Arthroplasty in Alkaptonuria: An Effective Option to Treat a Complication of a Rare Disease.

Introduction: Alkaptonuria (AKU) is a rare autosomal recessive disorder in which tyrosine metabolism is altered. There is a deficiency of the Homogentisate 1,2-dioxygenase enzyme (homogentisic acid oxidase) This enzyme is responsible for the metabolism of the tyrosine - homogentisic acid - in maleylacetoacetic acid. Accumulation of homogenous acid occurs in urine and conjunctival tissue in the second with important deleterious effects on cartilage and bone. The most limiting complication is progressive degenerative arthropathy, especially in the axial and load load-bearing joints, with a lower tendency to affect the shoulder. Because of its rarity little is known about the results of arthroplasties in these patients. Case Report: A 60 -years -old man, retired, with a history of right knee arthroplasty 6 years ago (performed in another hospital). Sent to the orthopedic consultation due to intense shoulder pain. The case was revealed to be a rare disease: arthropathy due AKU. He was treated with total shoulder reverse arthroplasty. Currently with two 2 years of follow-up, with excellent functional results. Conclusion: The most commonly performed procedure, in this patients, is the hip prosthesis and there are few reported cases of shoulder arthroplasty. However, the results of our follow follow-up are good and encouraging.