Lumbar Herniated Discs



Sciatica > 2/52 1.6%


M:F = 1:1


Most common L4/5 

L5/S1 inherently stable 


Risk factors


Sedentary lifestyle


Frequent driving

Heavy lifting 




Annulus Fibrosis

- circumferential, multilayered rim

- type 1 collagen fibres at 30o to horizontal

- peripheral nerve endings

- high resistance to torsional and axial loads


Nucleus pulposis

- hydrophilic PG + 70% water

- type 2 collagen

- resist axial compression



- nutrients diffuse from the end plate


Wiltse Classification


1.  Bulge 

- annulus diffusely extends beyond the plane of the disc space

- annulus intact / nil focal protrusion


2.  Protrusion

- focal bulging within margin of annulus

- diameter of base is greater than diameter of tissue displaced beyond disc space


Lumbar Disc Protrusion


3.  Extrusion

- under PLL

- mass of discal tissue of greater diameter than the aperature through which it has passed


Lumbar Disc ExtrusionL5 S1 Extruded Disc


4.  Sequestration

- free disc in canal

- fragment with no continuity with tissue in disc of origin


Sequestered Disc MRI 3Sequestered Disc MRI 2Sequestered Disc MRI 4Sequestered Disc MRI 1


Anatomical Classification


1. Central


Lumbar Central Disc Herniation MRICentral Lumbar Disc Herniation


2. Lateral Recess / Posterolateral

- between dura and foramina

- anterior: disc (annulus) and vertebral body

- posterior: facet joint, lamina, ligamentum flava

- lateral: foramen, L5 pedicle


Herniated disc lateral Recess S1 nerve root compressionL45 Posterolateral Disc


3. Foraminal

- anterior: body of L5, L5/S1 disc

- posterior: pars, apex of superior facet of S1


Foraminal Disc MRIForaminal Disc 2 MRI


4. Extra- Foraminal / Far Lateral


Pathophysiology Nerve Root




Poorly resistant to compression

- dural sheath instead of perineurium

- tethered between dura and foramen

- compression impairs blood flow to nerve



- asymptomatic nerve compressions

- studies suggest that normal nerve roots do not generate pain when compressed




Chemical factors

- make nerve root more susceptible to effects of compression





- traversing nerve root is L5

- exiting nerve root is L4


Posterolateral disc

- compresses traversing nerve i.e. L4/5 disc hits L5 nerve root

- this is most common situation


Foraminal disc

- compresses exiting nerve root i.e. L4/5 disc hits L4 nerve root

- require partial medial facetectomy / stand on opposite side of table


Far Lateral / Extra-foraminal disc

- compresses nerve root already exited i.e. L4/5 disk hits L4 nerve root

- Wiltse approach or complete facetectomy / follow nerve out




Typical patient 20-45 year old male



- leg in dermatomal distribution



- numbness / parasthesia / weakness


Cauda Equina Syndrome

- saddle anaesthesia / urinary incontinence / weak EHL




Tension signs


1.  SLR / Straight leg raise / Lasegue's Sign

- elevate leg from hip with knee straight

- reproduce pain below knee

- L5 / S1 nerve roots


Deville et al Spine 2000

- meta-analysis

- SLR very sensitive 90% but lower specificity 26%

- crossed SLR low sensitivity 29% but more specific 88%


2.  Femoral nerve stretch test

- patient prone, knee flexed, extend hip

- reproduces pain

- L4 nerve root



  Pain Sensation Weakness Reflex Test
L2 Lateral thigh Lateral thigh HF    
L3 Medial knee Medial knee Quads    
L4 Anteromedial knee Medial Malleolus T Ant Knee Jerk Femoral Stretch
L5 Dorsum foot First webspace EHL   SLR
S1 Sole / lateral foot Sole / lateral foot FHL Ankle Jerk SLR

DDx L4 nerve root

- CPN / DPN palsy

- test peroneals, tibialis posterior


DDx L5 nerve root

- CPN / DPN / Sciatic palsy

- test peroneals / abductors


DDx S1 nerve root

- tibial nerve

- test tibialis posterior




T2 Sagittal - myelogram


Lumbar MRI T1 Herniated DiscHerniated disc lateral Recess S1 nerve root compressionCauda Equina MRI


T1 Axial - see nerve root against white fat


Lumbar HNP T1 Axial




Infection / Tumour / Fracture




Non-operative Management





- 80% improve after 6/52

- 90% improve after 3/12

- 95% improve after 6/12


Weakness just as likely to resolve as pain


Results Operative v Nonoperative


Peul et al BMJ 2008

- RCT of conservative treatment v microdiscectomy

- symptoms 6 - 12 weeks

- earlier symptomatic relief in surgical group

- no difference at one or two years





- NSAIDs / opiates / steroids / tricyclic antidepressants


Physiotherapy / lumbar stabilisation exercises




Chiropractic manipulation


Epidural steroids


Price Health Technol Assess 2005

- multicentred RCT placebo control

- 220 patients with unilateral sciatica

- minimal and transient value over placebo at 3 weeks

- no difference after 6 weeks

- not cost effective / drain on resources


Arden et al Rheumatology 2005

- WEST study

- exactly the same findings


Transforaminal CS / Nerve Root Injections


Nerve Root Injection


Riew et al JBJS Am 2000

- RCT of patients with unilateral nerve root compression

- all considered suitable for operative intervention

- effectively prevented need for surgery in more than half of the patients

- LA + steroid more effective than LA alone


Operative Management


Absolute Indications


Cauda Equina Syndrome


Relative Indications


Failure of non operative treatment

Severe debilitating anatomical leg pain

Progression neurological deficit


Prediction of good operative outcome


6/6 Nachemson


1. Leg > back pain

2. Symptoms consistent with root irritation

3. Signs consistent with root irritation

4. Tension signs / positive SLR

5. Imaging consistent with Symptoms & Signs

6. Pain > 6 weeks





Standard Discectomy

- open

- microdiscecotmy

Percutaneous / Endoscopic Discectomy





- chymopapain dissolves nucleosus pulposis

- older technique largely out of favour




Muralikuttan et al Spine 1992

- RCT of discectomy v chemonucleolysis

- inferior short term results with chemonucleolysis

- no difference at one year





- suitable for noncontained disc




Dewing et al Spine 2007

- prospective followup of 183 single level lumbar discectomies

- average age 27

- 85% satisfied with surgery

- recurrent disc herniation in 3%

- better outcomes in L4/5 than L5/S1

- better outcomes in sequestered / extruded discs than contained discs

- poorer outcomes in smokers and patients with predominance of back pain


Righesso et al Neurosurgery 2007

- RCT of open v microdiscectomy

- no difference in outcome

- longer scar and inpatient stay in open group

- longer surgical times in microdiscectomy


Percutaneous Discectomy



- contained disc



- image guidance / endoscopic techniques

- interlaminar or transforaminal

- discectomy with cutting / suction probe



- minimal scar

- rapid recovery




Ruetten et al Spine 2008

- RCT of endoscopic interlaminar and transforaminal v microdiscectomy

- 82% relief of leg pain, no difference in each group

- 6% recurrence, no difference in each group

- reduced back pain and complications with improved rehab in endoscopic group


Complications Discectomy


Wrong level surgery


Neural injury

- paraplegia 1: 25 000

- nerve root injury

- cauda equina 0.2%


Dural tears


A.  Intraoperative Management

- head down

- stop ventilating / hand ventilate / anaesthetic valsalva

- ensure free abdomen

- CSF can make nerve root in danger / protect with patty

- attempt primary repair with 6.0 prolene non cutting needle

- supplement with Tisseel glue

- +/- fat graft / thoracolumbar graft

- subfascial drain

- bed rest 2 days


B.  Postoperative CSF leak

- ensure no meningitis symptoms

- glucose / microscopy test to confirm

- adequate fluids / head down / quiet room / bed rest

- antibiotics controversial

- MRI: small leak or large leak


Non operative Management

- insert drain below conus

- decreases CSF pressure

- bed rest / leave drain for 5 - 7 days


Operative Management

- failure nonoperative / large leak

- thoracolumbar fascia / synthetic graft repair


Incomplete decompression / failure to relieve symptoms


Infection 2%


Thromboembolism 1%


Arachnoiditis / Intradural fibrosis


Incidence 5%


MRI changes

1.  Central root clumping

2.  Empty sac appearance

3.  Soft tissue mass in subarachnoid space


HNP recurrence



- life long 6 - 7%

- second time 50%

- third time 90%



- gadolinium MRI

- scar enhances but recurrent HNP does not



- disc resection +/- fusion


Geere et al., BJJ 2023

- Retrospective cohort study 733 lumbar discectomies

- 12% recurrence rate over 5y

- Smoking was the major independent risk factor, HR 2.12