Study Design: Fifty‐eight patients came to two spinal surgeons with abnormalities adjacent to a previously fused thoracic or lumbosacral segment after they had been asymptomatic for more than 2 years. Radiographs, outcome analysis, analog pain evaluation, patient demographics, and medical indices were analyzed to evaluate risk factors for adjacent segment abnormality.
Objectives: Risk factors for adjacent segment breakdown and pathophysiology of adjacent segment breakdown were analyzed in this longitudinal study.
Summary of Background Data: Fifty‐eight patients underwent a thoracolumbar, lumbar, or lumbosacral fusion with an average symptom‐free period of 13.1 years before presentation with severe symptomatology necessitating further surgery at the adjacent segment.
Methods: Fifty‐eight patients with adjacent segment abnormality were analyzed by outcome assessment questionnaire, pain analog evaluation, radiographic studies, demographic factors, and sequential follow‐up evaluation. Thirty‐seven of these patients have been followed for more than 2 years after their adjacent segment surgery.
Results: Fifty‐eight patients developed spinal stenosis, disc herniation, or instability at a segment adjacent to a previously asymptomatic fusion that was done an average of 13.1 years earlier. Segments adjacent to the adjacent segment itself were as likely to breakdown (58%). Thirty‐seven patients were followed for more than 2 years, having outcomes defined as good or excellent in 70.3%. Seven of the 37 patients required an additional surgical procedure. Sagittal and coronal imbalances appeared to play a role in breakdown, although statistical significance was not evident.
Conclusions: This represents the largest series of adjacent segment breakdowns reported in the literature. The segment adjacent to the adjacent segment was almost as likely to breakdown. Sagittal and coronal alignment appeared to play a role in adjacent abnormality. Good outcomes are evident in 70% of cases.