Preventive Effect of Limited Decompression on Adjacent Segment Following Posterior Lumbar Interbody Fusion

Inclusion Criteria: * A clear diagnosis of lumbar spinal stenosis, and surgical level of L4-S1 (The levels to be operated on were decided by matching the clinical symptomatology with the radiological findings of the spinal levels that needed decompression); * Patients have asymptomatic pre-existing spinal canal stenosis (cerebrospinal fluid occlusion grade=1) at adjacent segment. * Failed at least eight weeks conservative treatment; Exclusion Criteria: * Unstable factors (slip, rotation, lateral bending, etc.) in adjacent segment L3/4; * Preoperative sagittal and coronal imbalance of the spine; * Lumbar infection and/or tumor diseases; * A previous history of lumbar fusion surgery.