Fracture of robust fusion mass after sequential long-construct instrumentation removal: illustrative case

BACKGROUND: Adult idiopathic scoliosis presenting after the age of 18 years affects 2%-4% of the adult population younger than 45 years. In the cases of multilevel spinal fusion, downstream complications, particularly pain and prominence, may warrant instrumentation removal. Even with proper fusion, deformity recurrence and loss of sagittal correction are common concerns. However, the literature on fusion mass fractures is minimal. OBSERVATIONS: A 52-year-old woman with a history of adult spinal deformity and posterior spinal fusion presented with discernable prominence at the proximal end of her instrumentation. Imaging confirmed a solid fusion mass, and sequential partial removal of her instrumentation was performed. Nine years after index removal, she returned with immediate pain following a low-energy injury. A subsequent CT scan showed a linear fracture line in her L3-4 fusion mass. Posterior fusion was performed with pedicle screw fixation of two levels above and below. LESSONS: Removal of thoracolumbar instrumentation poses potential risks, including fusion mass fracture, and requires careful risk-benefit analyses. https://thejns.org/doi/10.3171/CASE25582.