Interspinous process fixation versus posterior lumbar interbody fusion following decompression for single-level grade I degenerative spondylolisthesis: a retrospective propensity score-matched study

ISPF provided better short-term clinical recovery and maintenance of sagittal alignment, whereas PLIF offered greater slip correction. Both procedures yielded comparable long-term clinical outcomes, supporting individualized surgical decision-making in patients with degenerative LSS and Grade I spondylolisthesis.