Cervicosacral stabilisation in alkaptonuria: seven-year surgical management of multisystem ochronosis including joint arthroplasties.

Alkaptonuria (AKU) is an ultra-rare autosomal recessive disorder caused by homogentisic acid (HGA) accumulation, leading to ochronosis and progressive joint and spinal degeneration. Misdiagnosis as ankylosing spondylitis (AS) is possible due to overlapping spinal features.We present a man in his late 40s with ochronotic arthropathy, initially diagnosed as AS. Diagnosis was confirmed by elevated urinary HGA. Over 7 years, he underwent bilateral total shoulder, hip and knee arthroplasties, and long-segment cervicosacral fusion with pedicle subtraction osteotomy. Histopathology confirmed ochronotic cartilage changes. Surgical challenges included non-union, fascial dehiscence and tissue fragility. Cardiovascular evaluation revealed aortic valve stenosis and mitral insufficiency, reflecting systemic disease burden.The patient's spinal interventions preceded regulatory approval of nitisinone for AKU in the European Union, a disease-modifying therapy with potential to modify disease progression. This case underscores the importance of distinguishing AKU from inflammatory spondyloarthropathy and highlights the need for early diagnosis and interdisciplinary care.