Femoral head ochronotic pigmentation in a patient with alkaptonuria and secondary hip osteoarthritis.

Alkaptonuria is a rare autosomal recessive disorder caused by homogentisic acid dioxygenase deficiency, leading to ochronotic pigment deposition in connective tissues and secondary osteoarthritis. We report the case of a 59-year-old female with longstanding shoulder, spine, and hip pain, diagnosed with alkaptonuria at age 45. Imaging revealed generalized osteoarthritis, most severe in the lumbar spine and right hip. Despite multimodal management, hip pain progressed, requiring total hip replacement with significant functional improvement. The surgical specimen revealed characteristic dark-bluish ochronotic pigmentation of the femoral head. This vignette highlights the disabling musculoskeletal manifestations of alkaptonuria and the need for timely recognition and surgical management in advanced disease.