Lumbar Stenosis

DefinitionLumbar Stenosis


Reduction of space available for neural elements

- in spinal canal or intervertebral foramina

- due to degenerative changes, congenital abnormalities or both

- involves compression of the thecal sac or nerve roots




Onset 50 - 60's

- M = F

- associated with onset OA spine


L3/4 & L4/5 most common


Aetiological Classification


1. Congenital



- short thick pedicles and narrowed interpedicular distance




Idiopathic ~ Polynesians

- trefoil-shaped canal


Congenital narrow spinal canal

- most syptomatic patients have canals at lower end of spectrum



- narrow L3




2. Acquired



- most common aetiology

- disc desiccation / loss of height / bulging of annulus

- facet subluxation / capsular hypertrophy / osteophytes

- overall shortening of lumbar spine / decreased volume

- ligamentum flavum hypertrophy







- post-laminectomy

- post-fusion



- Paget's disease

- Fluorosis


- Ankylsing spondylitis

- Tumour

- Infection - TB


Traumatic / Post fracture


Anatomical Classification


1.  Central Canal Stenosis


2.  Lateral Recess Stenosis


3.  Foraminal




1.  Central canal


Posterior wall - ligamentum flavum & laminae

Lateral wall - medial facet joints & intervertebral foramina

Anterior wall - annulus fibrosis & posterior vertebral body


2.  Lateral recess


Extends from where nerve root leaves dural sac to where nerve root enters foramen


Posterior wall - ligamentum flavum & superior part of lamina

Anterior wall - posterior vertebral body & annulus fibrosis

Lateral wall - medial & inferior pedicle


3.  Intervertebral foramen


Extends from inner to outer foramen


Superior wall - inferior part of pedicle above

Inferior wall - superior part of pedicle below

Anterior wall - above is body, below is disc

Posterior wall - pars interarticularis, ligamentum flavum & apex of superior facet of vertebrae below




Stenosis typically at disc level either due to disc or facets


1.  Central Canal

- bulging of annulus posterior

- facet osteophytes posterolateral

- hypertrophied ligamentum flavum posterolateral


Lumbar MRI Stenosis Trefoil Canal


2.  Lateral Recess

- facet subluxation & osteophytes + hypertrophied ligamentum flavum


3.  Intervertebral Foramen

- loss of disc height with approximation of pedicles

- inferior annular bulge

- medial facet hypertrophy





- increased canal narrowing with extension

- also get posterior disc protrusion and redundancy of ligamentum flavum

- root lacks perineurium & hence more susceptible to compression



- interference with metabolic demands of nerve root

- exercise increased nutritional requirements & waste production

- canal constriction limits response = relative ischaemia




Back Pain



- L5 most common, then S1


Neuropathic claudication

- insidious onset

- usually bilateral

- diffuse / no dermatomal pattern

- buttocks / thighs / calves

- heaviness / weakness / burning / cramping / tingling / numbness


Worse with walking, standing & lumbar extension


Relieved by sitting, flexion, walking upstairs, squatting




Often none, but can overlap with HNP




Vascular claudication

- calf pain with exercise

- rapid relief with cessation walking

- no back pain / no numbness

- abnormal pulses


Hip Disease

Diabetic neuropathy

Retroperitoneal pathology




Rule out 

- infection / tumour / fracture


Confirm degenerative changes

- facet hypertrophy / disc narrowing

- decreased AP diameter of canal

- identify associated pathology i.e. spondylolisthesis / scoliosis




T2 Sagittal "MRI Myelogram"


Lumbar MRI Stenosis Sagittal T2Lumbar Stenosis MRI SagittalLumbar Stenosis MRI


Stenotic Measurement


A.  Volume

- more accurate

- critical area is 100 mm2


B.  AP diameter less accurate

- normal if > 12mm

- absolute stenosis if < 10mm


Intervertebral foramina

- no fat about nerve root

- reduced height


Lumbar Foraminal Stenosis L45 MRILumbar MRI Tight Intervertebral Foramina L3


B.  Axial slices



- no fat about dura

- trefoil shape canal

- lateral recess or foramina compression

- nerve root compression


Lumbar MRI Stenosis Trefoil CanalLumbar stenosis axial MRILumbar MRI Axial Stenosis




Not clear not all patients progress


Johnsson 1993 Clin Orthop

- 32 patients followed 4 years

- 70% unchanged

- remainder: half worse, half better




Non-Operative Management




Rest / Avoid aggravating activities



- simple analgesia

- short course NSAIDS


Back support

- prevent extension



- back strength in flexion

- stabilise abdominal muscles

- aerobic fitness on exercise bike 


Epidural steroids


Koc et al Spine 2009

- RCT of exercise v epidural steroids v control in spinal stenosis

- exercise and epidural steroids both effective up to 6 months




Podichetty et al Spine 2004

- RCT of calcitonin v placebo

- no difference in two treatment groups


Operative Management






Cauda equina syndrome




Failure to respond to non operative treatment

Disabling neurogenic claudication

Progressive neurological deficit


Back pain is not an indication




Decompression +/- fusion


Interspinous devices

- limit extension


Indications for fusion


1.  Degenerative Spondylolisthesis


2.  Radiological instability

- > 3mm or > 11o


3.  Intra-operative destabilisation

- removal of > 1 facet joint or pars

- i.e. radical decompression required laterally


4.  Degenerative scoliosis


5.  Significant low back pain / disc degeneration




Define site of compression

- central / lateral recess / foramina


Define levels

- single / multilevel



- must be prepared to fuse if cause instability

- consent




Operative v Non Operative


Weinstein et al Spine 2010

- SPORT trial

- RCT of operative v non operative treatment lumbar stenosis

- 289 patients with 4 year follow up

- substantially improved pain and function in operative group


Interspinous Devices


Hsu et al J Neurosurg Spine 2006

- RCT of non operative v X Stop interspinous device

- significant improvement in QOL, with results similar to surgical decompression


Decompression v Fusion


Niggemeyer et al Eur Spine J 1997

- meta-analysis

- if symptoms < 8 years, decompression without fusion yields best results

- if symptoms 15 years or more, decompression with instrumented fusion best results

- decompression and fusion without instrumentation had worst results




Epidural haematoma



Nerve root injury

Dural Tears


Technique L4/5 Decompression



- abdomen free to limit venous pressure and bleeding

- 4 poster / knee below hips / arms on bolster

- feet / knees / elbows / face / eyes cushioned


- betadine packs in buttocks

- +/- Jackson table (enables more lordotic position if instrumentation planned)


Landmarks / Check level

- iliac crest L4/5 interspinous space

- prep area aseptically, spinal needle

- check with lateral x-ray

- square drape



- inject LA with A

- midline

- meticulous haemostasis

- divide thoracolumbar fascia


Superficial Dissection

- subperiosteal elevate of supraspinous muscles (Cobb's and diathermy)

- sequentially pack with rolled swabs / sausages to control bleeding

- out to lateral extent of pars

- expose facet joints, but preserve capsule if not fusing

- beware parafacetal arteries

- don't extend between transverse processes as nerve root at risk


Deep dissection (L4/5)


L4 5 DecompressionL4 5 Decompression Laminectomy


Recheck level

- L4/5 interspinous gap


Resect L4 spinous process

- remove ligamentum flavum above and below

- Kerrison Rongeur / knife

- remove all of L4 lamina

- expose L4/5 disc space

- L5 nerve root exits inferior

- L5 nerve root will pass below L5 pedicle


Remove L4/5 disc fragments if needed

- nerve root retractor

- gently retract dura to each side

- take out with pituitary rongeur


L4/5 medial facetectomy

- above L5 pedicle

- L5 nerve root exits inferior to it

- decompress, pass Watson Chaney


Preserve pars & half of facet

- may have to remove entire facet joint & pars

- preserve one facet joint at each level

- can be 1/2 on each side