Lumbar Discectomy Techniques

Disectomy Technique for Posterolateral L4/5 disc 




L4/5 disc at level of facet joints


Interlaminar space is below disc

- have to take inferior aspect of superior lamina


Pedicle and transverse process at same level


Disc usually on one side

- hemilaminotomy

- no need to remove spinous process

- this preserves stability




4 poster support

- abdomen free (decrease venous drainage) / Jackson Table

- knees below hips

- pillows under legs and feet

- pressure care knees

- arms forward on supports

- back level & slightly head down

- protect eyes / CPN at knees / ulna nerve at elbows


Pre-Operative antibiotics


Often dressing + betadine in natal cleft




Careful correlation of clinical and MRI

- level of disc

- side of disc


Iliac Crests L4/5

- mark

- prep with antimicrobial solution

- insert 18G needle into L4/5 interspinous space

- obtain cross table xray to confirm level

- this centres incision




Square drape

LA with adrenalin

Incise skin L4 spinous process to S1 spinous process


Superficial Dissection


Divide thoracolumbar fascia

- in midline down to spinous processes

- subperiosteal dissection down side of spinous process

- with cobb / diathermy

- preserve suprasinous ligament


Subperiosteal dissection to lamina on lesion side

- expose but don't disturb facet joint capsule

- self retractor inserted

- don't go between transverse processes


Lamina spreader between spinous processes

- under supraspinous ligament

- opens up interlaminar space


Recheck level at L4/5 interspinous


Disc Localisation


5 ways to identify L5/S1



- hollow sound 

- non mobile

- midline crest with no ligamentum flavum / interlaminar space

- anterior slope L5 lamina

- large L5 S1 interlaminar space


Lumbosacral Junction


Deep Dissection


Expose Ligament Flavum 

- attaches on top of inferior lamina to superior lamina

- find midline raphae

- incise flavum with scalpel over inferior laminae

- create flap of flavum

- use Watson Cheyne Dissector to gently dissect off dural adhesions

- remove flavum laterally 

- 1, 2 or 3 mm 40° Kerrison Rongeur

- see fat overlying blue dura


Remove inferior aspect of superior lamina

- will take up to L4/5 disc 

- resect medial two thirds of superior facet /  lower one third inferior facet


Lumbar Spine PosteriorLumbar Spine HemilaminotomyLumbar Intervertebral Foramen


Exiting L4 nerve root

- above L5 pedicle


L5 nerve root

- below L5 pedicle

- remove inferior lamina and pars




Retract dura gently

- dural retactor

- remove sequestered disc with pituitary rongeur

- cruciate incision in PLL to remove protruding / extruding disc


L5 nerve root

- exit under pedicle L5 inferiorly

- medial facetectomy

- follow root out laterally around pedicle

- ensure free passage through foramina 

- should be able to pass Watson Cheyne easily


L4 nerve root

- L3/4 interlaminar space

- remove inferior lamina and pars

- will pass under pedicle of L4 inferiorly

- medial facetectomy of L3/4 facet joint

- access L4 pass under pedicle of L4 superiorly


Wiltse Approach to Extra-Foraminal Disc




Paramedian incision

- 2 fingerbreadths / 5cm lateral to midline


Superficial Dissection


Muscles split to intertransverse ligament

- between Longissimus & Multifidus

- always a bleeder on the way down

- clear transverse processes

- preserve posterior ramus by hooking finger around & then follow ramus to nerve


Deep Dissection 


Removed intertransverse ligaments and fascia between TP

- nerve root anterior to fascia and just below TP

- runs at a 45o angle

- follow nerve medially and identify disc

- retract nerve laterally & remove disk

- may have to incise annulus to remove bulge

- if intra-foraminal element, remove lateral facet


Post operatively


Symptoms should be immediately relieved



Watch retention

No anticoagulation

Mobilize ASAP

No heavy lifting 6/52