Adjacent Segment Disc Disease

Spinal fusion surgery involves the fusion of two or more vertebral bones, and is a standard of care for spinal deformities and conditions such as radiculopathy, myelopathy and spondylolisthesis. However, in the long-run, the surgery may be associated with adjacent segment disc disease, a complication in which the spinal segments above and below the fused portions develop abnormalities such as disc degeneration, instability, spinal stenosis or disc herniation. This occurs as a result of increased stress on these segments owing to a compromised spinal column. The greater the number of segments involved in the fusion, the greater the stress experienced at the adjacent segments. The complication is more frequently associated with fusions of the lumbar spine (lower back vertebrae) rather than the cervical spine (neck vertebrae).

Adjacent segment disc disease is associated with new degeneration symptoms, but may be asymptomatic and identified only during a follow-up imaging test. Sometimes, clinical evidence of degeneration may not accompany radiographic changes. Surgical intervention is decided only in the presence of clinical as well as imaging findings. Treatment includes fusion as well as decompression of the adjacent segment.