Spinal disassociation masquerading as iatrogenic listhesis above a previous fusion

Abstract

Study design: A case of remarkable instability adjacent to an L5-S1 fusion is reported.

Objectives: The objective of this study was to review a case of marked instability adjacent to a prior fusion. Diagnostic workup and surgical management options are discussed.

Summary of background data: Junctional degeneration above or below the levels of a spinal fusion may be associated with instability. We present an unusual case of instability whose severity was only apparent when the patient was under general anesthesia.

Materials and methods: A 52-year-old man with a history of prior L5-S1 fusion presented with severe back pain and lower extremity weakness. Workup including multiple imaging methods revealed junctional degeneration and a Grade I spondylolisthesis at L4-L5 with minimal translation on dynamic imaging. Operative intervention was planned.

Results: Intraoperative imaging revealed marked distraction at the L4-L5 disc space not apparent on preoperative dynamic films. The surgical approach was modified accordingly.

Conclusions: Adjacent segment degeneration next to a prior lumbar fusion may be associated with extreme instability. Treatment may require complex stabilization.