Overview
Degenerative lumbar spinal stenosis is a progressive disorder of the whole motion segment (Kirkaldy-Willis cascade). Disc degeneration causes relative instability and facet hypermobility; increased facet loading leads to facet (especially superior articular process) hypertrophy, and ligamentum flavum thickening and calcification further narrow the canal. Venous congestion and hypertension of the compressed neural elements are thought to produce neurogenic claudication. L4-5 is most commonly involved, followed by L5-S1 and L3-4. (Campbell)
Anatomy and Classification (Campbell)
Central stenosis (between the facets): disc protrusion, bulging annulus, osteophytes or buckled ligamentum flavum; causes neurogenic claudication with diffuse leg pain.
Lateral canal (Lee zones): entrance zone or lateral recess (from the medial superior articular process to the medial pedicle; facet arthritis is the usual cause), midzone or foraminal region beneath the pars (pars fracture fibrocartilage, lateral disc, flavum extension), and exit zone lateral to the facet (far-lateral disc, spondylolisthesis, facet arthritis). Lateral compression causes radiculopathy.
Types: congenital (idiopathic short pedicles, achondroplasia), acquired degenerative (central, lateral recess or foraminal, degenerative spondylolisthesis or scoliosis), iatrogenic (postlaminectomy, postfusion), post-traumatic and miscellaneous (Paget disease, which responds to calcitonin, fluorosis, DISH).
Natural History (Campbell)
Many patients have marked radiographic narrowing with few symptoms, and canal diameter correlates poorly with symptoms. The course is usually insidious and stable; 15% to 50% improve with nonoperative care, and about half report improvement after 8 to 10 years. In a randomized study, 80% of operated patients had good results at 4 years versus about 50% treated nonoperatively, whose results deteriorated over time. SPORT showed significantly greater improvement with surgery. Worsening despite adequate conservative treatment is an indication for surgery.
Clinical Evaluation (Campbell)
Symptoms: back pain (95%), sciatica (91%), sensory disturbance (70%), weakness (33%) and urinary disturbance (12%). Central stenosis gives bilateral nondermatomal buttock and posterior thigh pain; lateral recess stenosis gives dermatomal pain, more pain at rest and at night, but better walking tolerance.
Neurogenic versus vascular claudication:
Feature | Vascular | Neurogenic |
|---|---|---|
Walking distance | Fixed | Variable |
Relief | Standing still (about 5 min) | Sitting or bending forward (may take 20 min) |
Uphill walking | Painful | Better tolerated |
Bicycle test | Painful | Painless |
Pulses | Absent | Present |
Skin | Hair loss, shiny | Normal |
Positive "shopping cart" sign (flexion improves endurance) and "stoop test" (symptoms ease when the patient stoops or sits bent forward after brisk walking).
Physical findings are inconsistent: check distal pulses and hip rotation; straight-leg raise and neurologic examination are often normal at rest but may become abnormal after walking to the pain limit.
Radiographs give hints (short pedicles, narrow interpedicular distance, facet hypertrophy); MRI or CT myelography confirms and localizes stenosis.
Surgical Principles (Campbell)
Decompression by laminectomy or fenestration is the treatment of choice. Laminectomy suits older patients with severe multilevel stenosis; fenestration (bilateral laminotomies with partial facetectomies preserving midline structures) suits younger patients with intact discs and can be performed minimally invasively, with fewer complications and less instability.
Add fusion when resection compromises stability, or with isthmic or degenerative spondylolisthesis, scoliosis or kyphosis, adjacent segment degeneration after fusion, or recurrent stenosis or disc herniation after decompression. Removal of more than one complete facet may require instrumented fusion; radical decompression of a single root usually does not. TLIF is an option when ipsilateral recess and foraminal decompression are both needed. Prepare for fusion in case findings demand it.
Localize the pain generator preoperatively with selective root blocks to allow a focused decompression.
Setup: prone with the abdomen free to reduce bleeding; keep hips extended if fusion is likely (avoid a kyphosing frame). Use a microscope or loupes and headlamp.
Beware adhesions and dural tears even in virgin cases. In tight recesses, thin bone with a small sharp osteotome or high-speed burr and remove it with angled curettes rather than forcing a Kerrison. The lateral recess is best viewed from the opposite side of the table.
Start decompression where stenosis is least severe and work toward the worst area. Treat a coexisting disc herniation at the same time.
Technique 46.15: Midline Decompression (Neural Arch Resection) (Campbell)
General anesthesia, prone on the chosen frame. Midline incision centered over the stenosis; confirm the level radiographically.
Strip muscle subperiosteally from spinous processes and laminae to the facets, exposing the pars; do not damage uninvolved facet joints.
Remove the spinous processes of the levels to be decompressed.
Remove the laminae with a Kerrison rongeur or high-speed burr up to the ligamentum flavum insertion (thin a thick lamina with a diamond or side-cutting burr first). Detach the flavum with a curette. Take care because neural structures are compressed and instrument space is minimal; starting lateral recess decompression with the burr before removing the flavum avoids placing a rongeur into a tight canal. Remove lamina until the pedicles can be felt.
Using the pedicle as a guide, identify each nerve root and trace it to the foramen.
Remove the medial part of the superior facet forming the roof of the lateral recess with a chisel or rongeur. Check foraminal patency with an angled elevator or graduated probes and undercut into the foramen as needed, removing no more than half of the pars.
Inspect the disc and remove gross herniations unilaterally; avoid bilateral annulotomy, which compromises stability. Remove a ventral annular or bony ridge only if it kinks the root, in a bloodless field.
Decompress all symptomatic levels from the caudal edge of the most proximal pedicle to the cephalad edge of the most distal pedicle, seeing the lateral dural margins in each recess. Probe every foramen: inadequate foraminal decompression is a common cause of failure.
Achieve hemostasis with bipolar cautery and temporary thrombin-soaked gelatin sponge, check for CSF leak, and consider a free fat graft over the laminectomy defect before closure.
Outcomes and Complications (Campbell)
Number of levels does not affect results. Poorer outcomes are associated with unclear radiographic confirmation, female sex, litigation, prior failed surgery, spondylolisthesis, hip arthritis, diabetes and cardiac comorbidity. One series reported 62% to 67% success with deterioration by 5 years and 18% reoperation; overall reoperation is 9% to 23%.
About 30% develop some anterolisthesis after decompression, which is often well tolerated; observe before recommending fusion.
Complications are more frequent with comorbidities, especially diabetes: dural tear, epidural hematoma, instability, adjacent segment degeneration (35% to 45% after fusion, symptomatic in about 30%). For thromboprophylaxis, use mechanical compression and early ambulation, because pharmacologic agents carry a greater risk of epidural hematoma than of pulmonary embolism.
References
Thompson KM. Degenerative disorders of the thoracic and lumbar spine. In: Azar FM, Sawyer JR, Throckmorton TW, eds. Campbell's Operative Orthopaedics. 15th ed. Philadelphia: Elsevier; 2026. Chapter 46, Stenosis of the thoracic and lumbar spine.