Alkaptonuria presenting as lumbar degenerative disease: A case report and literature review

Alkaptonuria (AKU) is a rare, inherited metabolic disease caused by deficient activity of homogentisic acid oxidase, leading to the accumulation of homogentisic acid and its oxidized product, benzoquinone acetic acid. These compounds cause black discoloration of cartilage, degeneration, inflammation, and calcification of intervertebral disks and large joints, resulting in pain and impaired quality of life. Despite its debilitating effects, there are no curative treatments for AKU, and management remains supportive. This study aims to contribute to the limited literature on AKU-related spinal manifestations by reporting a case of lumbar degenerative disease in an AKU patient and highlighting surgical intervention as an effective treatment approach.

A 49-year-old woman presented with chronic lower back pain and the posterior side of right lower limb radiating pain for 1 year, worsening over the past week. Magnetic resonance imaging revealed lumbar spondylolisthesis at the L4/5 level and migrated lumbar disk herniation at the L5/S1 level.

The patient underwent transforaminal lumbar interbody fusion surgery at L4/5 and L5/S1. Intraoperatively, the resected disk material was black, with darkened intervertebral disks and cartilage endplates, distinct from the typical white appearance of degenerative disks. Surgical intervention included disk and cartilage endplate removal, insertion of cages with harvested autografts, and implantation of bilateral pedicle screws and rods.

AKU with lumbar degenerative disease.

The patient experienced resolution of pain postoperatively.

This case underscores the importance of recognizing AKU as a potential cause of lumbar degenerative disease and highlights transforaminal lumbar interbody fusion surgery as a viable treatment option for pain relief and improved functionality in affected individuals.