Laminectomy alone vs laminectomy with posterior fusion in lumbar spinal stenosis: The role of instability

Table 3 Comparison of international guideline recommendations for lumbar fusion in lumbar spinal stenosis according to instability status

Criterion/element	NASS	WFNS	CSORN (DSIC)	NICE	JOA
Definition of instability	Numerical thresholds: > 4-5 mm translation or > 10°-15° sagittal rotation (up to 20° at L4-L5). > 2 mm translation in stenosis	No numeric thresholds; based on radiographic and clinical judgement	Scoring system integrating translation ≥ 4 mm, kyphotic/neutral disc angle, disc height > 6.5 mm, facet effusion, and back pain severity	No numeric thresholds; not explicitly defined	Requires radiographic evidence; no specific motion cut-offs
Primary indication for fusion	Definitive radiographic instability; > 50% facet removal; recurrent herniation; ≥ 2 mm spondylolisthesis; symptomatic adjacent segment disease; pseudarthrosis	Radiographic or functional instability; extensive facet removal; recurrent stenosis; sagittal/coronal deformity; pseudarthrosis	Type III (unstable) DSIC score; some type II (borderline) cases based on clinical judgement	Only when instability is clearly present; decompression alone in most borderline cases	Radiographic instability is similar to NASS criteria
Controversial areas	Lower threshold for fusion in degenerative spondylolisthesis (grade B for < 20% slip)	Broader use of fusion for functional instability without measurable motion	Borderline (type II) category may lead to over- or under-treatment; lacks RCT validation	Most conservative; may undertreat subtle instability	No numeric thresholds may lead to variation in interpretation

NASS: North American Spine Society; WFNS: World Federation of Neurosurgical Societies; CSORN: Canadian Spine Outcomes Research Network; DSIC: Degenerative Lumbar Spondylolisthesis Instability Classification; RCT: Randomized controlled trial; NICE: National Institute for Health and Care Excellence; JOA: Japanese Orthopedic Association.