Adjacent segment disease (ASD) in the lumbar spine is a well-known sequela of lumbar fusion surgery. The annual incidence of adjacent level re-operation is approximately 3% with a ten-year prevalence of 20-30%. Frequently, the surgical treatment involves decompression of the adjacent level coupled with extension of the instrumentation and fusion. Advocates of this paradigm cite the altered kinematics and biomechanics of levels adjacent to a lumbar fusion mass. Furthermore, decompressed levels adjacent to a fused segments are associated with higher rates of ASD in retrospective studies. Yet, a retrospective review of higher quality data concluded decompression adjacent to single-level fusion provides similar outcomes compared to fusions extending across the decompressed segments.

Given the conflicting data currently available, higher quality data are needed to guide surgical decision-making in ASD. The purpose of this trial is to prospectively compare decompression and decompression with fusion in patients with lumbar ASD.

Inclusion Criteria:

• Adult patients at least one year removed from a previous instrumented posterior lumbar fusion
• Patients with any prior posterior fusion involving L2 to the sacrum, whether single-level or multilevel
• Patients with symptoms related to central and lateral recess at the supradjacent level that have persisted despite at least six weeks of non-operative therapy modalities

Exclusion Criteria:

• Patients with previous uninstrumented lumbar fusions
• Patients with traumatic, neoplastic, or infectious etiologies at the adjacent segment
• Patients with prior iliac or sacroiliac fixation and those with nonunion as the primary indication for surgery
• Patients with pre-existing instability at the supradjacent level. The definition of instability will be determined based on standing lateral, flexion and extension plain radiographs. Patients with >3mm of change between these views will be excluded.
• Retrolisthesis will not be a criterion for exclusion

Adult patients at least one year removed from a previous instrumented posterior lumbar fusion will be considered for inclusion in this trial. Any prior posterior fusion involving L2 to the sacrum will be included, whether single-level or multilevel. Patients with symptoms related to central and lateral recess at the suprajacent level that have persisted despite at least six weeks of non-operative therapy modalities will be eligible.