Surgery of the Thoracolumbar Spine

Surgery of the

Thoracolumbar Spine

 

Thoracic spine

Lumbar spine

43

53

Viva questions

60

 

Daniel P Ahern, Joseph S Butler, Matthew Shaw and Sean Molloy

 

Thoracic spine‌‌‌‌

Posterior thoracic surgery

Scoliosis correction

Choice of approach

• There is an increasing trend towards posterior-only surgery. However, much depends on the characteristics of the curve and on the surgeon’s training and preference.

• Thorough discectomy is only possible with an anterior approach; thus very stiff curves may benefit from anterior release prior to posterior surgery.

• Thoracolumbar/lumbar curves are often treated with anterior instrumentation, especially if there is no thoracic curve.

• Posterior instrumentation allows fixation to the pelvis – an advantage in long fusions in the elderly and in non-walking patients with neuromuscular-type curves.

  Indications

• Severe deformity

• Curve progression

• Radicular pain or neurological deficit (degenerative cases)

• Back pain failing conservative measurement (rare)

  Risks

• Mortality 0.03%

• Respiratory dysfunction

• Neurological deficit: complete 0.03%; incomplete 1.5%

• Revision surgery 5%

• Failure to achieve complete curve correction

• Damage to sympathetic chain, major vessels

• Infection 1%–2%

• Blood loss

   

   

   

   

   

  Figure 4.1 A thoracic flexion compression fracture with kyphosis.

   

• Scar

• Imbalance, shoulder height discrepancy

• Back pain

• Blindness 0.028%–0.2%

   

  Operative planning

• Full history and examination

• Full spine radiographs including bending films:

  • Bending films to assess flexibility of spine

  • Identifying the correct level in the thoracic spine is more of a challenge as the reference points of the sacrum or C2 are not available. Therefore, it is important to check the number of ribs a patient has on plain X-ray, as these can be used to mark the skin using fluoroscopy prior to incision

• Whole spine MRI

• Multidisciplinary team involvement

• Anaesthetic and medical workup

• Lung function tests, chest radiograph, electrocardiogram (ECG)

• Cord monitoring arrangement

• Intensive care unit (ICU) bed arranged

   

   

   

   

   

  Figure 4.2 Thoracic vertebrectomy with posterior stabilisation for a solitary metastasis.

  Surgical procedure

• General anaesthesia

• Prone positioning:

  • Montreal mattress, Jackson table, four-post frame or similar

  • Arms can be placed by the patient’s side or out in front (depending on the level of surgery and the need to use X-ray)

• Protect pressure areas, eyes:

  • It is important that the shoulders are not hyperflexed or abducted and there is no pressure on the axilla, which could cause a nerve palsy

  • Padding is used under the patient’s elbows to avoid an ulnar nerve palsy

  • No pressure on the eyes

  • Table should be slightly head up to decrease central venous pressure

• Mechanical deep vein thrombosis prophylaxis

• X-rays on display

• Incision:

  • Skin:

    • Note the pedicle entry point will be above the spinous process of the vertebra counted and therefore the skin incision should allow for this

• Dissection:

  • Subcutaneous fat and fascia

  • Spinous process identified and subperiosteal dissection:

    • Ensure haemostasis – diathermy, gauze packing

  • Dissection to identify transverse processes, medial and lateral borders of the facet joints, and the pars

     

• Pedicle screw insertion:

  • In general, at the junction of the medial two-thirds and lateral one-third of the facet joint

• Decortication of facets and lamina

• Reduction

• Rod insertion

  • +/− Cross-links

• Closure in layers

  • +/− Drain insertion

  Postoperative care

• Neurovascular observations and analgesia

• Postoperative haemoglobin and renal function

• No spinal precautions – mobilise as pain allows

• Postoperative full spine X-rays

  Posterior thoracic decompression and fusion

  Indications

• Unstable thoracic fracture

• Posterior cord compression from a tumour or degenerative process

• Palliative procedure from an anterior compressive pathology

  • Where patient condition does not allow for anterior approach

• Disc pathology as part of costotransversectomy

• Coronal or sagittal deformity correction

   

  Risks

• Mortality

• Infection: 2%

   

   

   

   

   

  Figure 4.3 A fracture dislocation of the thoracic spine stabilised with posterior thoracic rods and screws.

   

• Neurological injury

  • Higher rate in the thoracic spine as canal dimensions smaller

• Wrong level surgery

  • Higher rate in thoracic spine – reference points of C2 and sacrum not available

• Blindness 0.02%–0.2%

• Thromboembolism

• Respiratory infection

• Failure/fracture of fixation

  Operative planning

• Full history and examination

• Radiographs/computed tomography (CT)/magnetic resonance imaging (MRI)

• Anaesthetic and medical workup/optimisation as appropriate

  Surgical procedure

• General anaesthesia

• Prone positioning

  • Montreal mattress, Jackson table, four-post frame or similar

• Arm positioning

  • May be placed on patient’s side or out in front

    • Dependent on level of surgery and use of intraoperative imaging

  • Beware not to hyperflex or abduct when position arms overhead (less than 45° abducted and less than 90° hyperflexed)

• Pressure area padding

• Midline incision

• Dissection

  • Skin, fat and fascia with haemostasis control

• Paraspinal musculature stripped from spine

• Dissection for landmark identification

  • Transverse processes, medial and lateral borders of the facet joints and the pars

     

    T2/3 T3/4

    T4/5

    T2 T3

    T5

    T7

    T2 Superior border of scapula. T2/3 Suprasternal notch.

    T3 Medial end of spine of scapula. Spine of T3 is posterior end of oblique fissure lung.

    T3/4 Top of arch of aorta.

    T4 End of arch of aorta. Azygos vein enters SVC.

    T4/5 Manubriosternal junction. (Angle of Louis.) Start of arch of aorta. T5 Thoracic duct crosses midline.

    T7 Inferior angle of scapula.

    T8 Caval opening in diaphragm. (IVC & right prenic nerve.) Left phrenic

    T8

    T10 T12

    pierces diaphragm. Hemi-azygos veins cross to left.

    T10

    Oesophageal opening in diaphragm (oesophagus, branches of left

    gastric vessels, vagus nerves).

    T12 Aortic opening in diaphragm. (Aorta, azygos vein, hemi-azygos vein, thoracic duct.) Coeliac axis.

    Splanchic nerves pierce crura. Sympathetic trunk passes behind medial arcuate ligament. Subscostal bundle passes behind lateral arcuate ligament.

     

     

     

    Figure 4.4 Thoracic structures corresponding to various vertebral levels.

     

    Pleura over oesophagus

     

    Pleura over azygos vein

    Pleura over intercostal

    vein

     

    Incision in pleura

    Intercostal

    muscle

    Pleura over medial end of rib

     

    Pleura over paravertebral ganglion

    External suface of retracted rib

     

     

     

    Figure 4.5 The selection of rib level in anterior scoliosis surgery.

     

• Pedicle screw insertion

  • Medial and lateral borders of the facet joints give the medial and lateral starting points for the pedicle screws

  • In craniocaudal direction, pedicle screw direction is approximately 90° to the translamina line

• Decompression

  • After instrumentation gives more protection to the neural elements than during instrumentation

    • +/− Drain insertion

• Closure in layers

  Postoperative care

• Adequate analgesia

• Neurological observations including formal postoperative neurological examination

• No spinal precautions – patient allowed to sit to any angle and mobilise as pain allows

• Postoperative radiographs

   

  Anterior thoracic surgery Scoliosis (anterior release) Indications

• Same as posterior procedure

  • Severe deformity

  • Curve progression

  • Radicular pain or neurological deficit (degenerative cases)

  • Back pain failing conservative measurement (rare)

     

    Risks

• Mortality 0.03%

• Respiratory dysfunction

• Neurological deficit: complete 0.03%; incomplete 1.5%

• Revision surgery 5%

• Failure to achieve complete curve correction

• Damage to sympathetic chain, major vessels, thoracic duct

• Infection 1%–2%

• Blood loss

• Scar

• Imbalance, shoulder height discrepancy

• Back pain

  Operative planning

• Full history and examination

• Full spine radiographs including bending films

  • Bending films to assess flexibility of spine

• Whole spine MRI

• Multidisciplinary team involvement

• Anaesthetic and medical workup

• Lung function tests, chest radiograph, ECG

• Cord monitoring arrangement

• ICU bed booked

  Surgical procedure

• General anaesthetic

• Lateral position

  • Convexity of the curve facing upwards

• Pressure areas padded

• Incision

  • In line with proposed rib

  • Note that rib level to be entered should be two levels above the superior vertebra being instrumented due to downward slope of ribs

• Dissection

  • Skin, fat and muscle are incised in line with the rib

  • Maintain haemostasis

• Periosteum stripped off the rib as far posteriorly as possible

• Anteriorly, rib is exposed to costochondral junction, then cut and removed

• Expose and carefully incise pleura and expose lung

• Retract lung superiorly using wet packs

• Posterior pleura is then incised

• Beware underlying segmental vessels

• If procedure is to cross the thoracolumbar junction, the diaphragm will need to be taken down

  • Before or after entering pleural cavity, costal cartilage is incised

  • Abdominal musculature is divided inferomedially – Beware risk of damage to peritoneum

     

  • Retroperitoneal fat entered deep to the costal cartilage

  • Peritoneum is reflected anteriorly using blunt finger dissection/gauze swabs

  • Dissection is carried down to the spine, anterior to the psoas muscle

  • Diaphragm is divided (with electrocautery) – A 2 cm peripheral cuff is left for repair

  • Great vessels and viscera are carefully reflected anteriorly and protected with blunt retractors throughout procedure

• Once exposure is complete, individual segmental vessels can be tied, cauterised or preserved

• Disc material is removed piecemeal until posterior longitudinal ligament is visualised

• Cartilaginous end plates are removed using a Cobb, osteotome or curette

  • Ideally, bony end plates should not be breached as this markedly increases blood loss

• Instrumentation

  • Important to appreciate rotation of the curve and relationship of vertebral body to spinal canal

  • Achieving a ‘cadence’ of screw insertion with the apical screw being most posterior will assist in de-rotation of the spine

  • Bicortical fixation aids stability

• Following screw insertion, a rod is applied

• Reduction

• Screw and rods are applied to the convexity of the curve; therefore, compression between individual screws aids reduction

• Closure

  • Posterior pleura may be left open or closed – surgeon preference

  • Diaphragmatic repair

  • Chest wall closed in layers

  • Chest drain inserted

  • Superficial closure

    Postoperative care

• Neurovascular observations and analgesia

• Postoperative haemoglobin and renal function

• No spinal precautions – mobilise as pain allows

• Postoperative full spine X-rays

   

  Thoracic discectomy +/− corpectomy

  Indications

• Disc prolapse

• Other compressive pathologies

  • Fracture

  • Tumour

    Risks

• Mortality less than 1%

• Respiratory infection

   

   

   

   

   

   

  Figure 4.6 Anterior scoliosis correction.

   

   

• Anterior chest wall pain

• Major vessel damage 2%–15%

• Neurological compromise

• Cosmesis of scar

• Thromboembolism less than 1%

• Back pain

• Wrong level surgery

   

  Operative planning

• Full history and physical examination

• Imaging – radiographs, CT, MRI

• Anaesthetic and medical workup/optimisation

• Appropriate cardiothoracic/vascular backup available

   

  Surgical procedure

• General anaesthesia

• Lateral position

  • Sand or bean bag commonly placed underneath operative site to aid exposure and open disc spaces

  • Pressure areas padded

• Incision

  • In line with proposed rib

  • Note that rib level to be entered should be two levels above the superior vertebra being instrumented due to downward slope of ribs

• Dissection

  • Skin, fat and muscle are incised in line with the rib

  • Maintain haemostasis

• Periosteum is dissected off the rib and rib freed circumferentially from underlying soft tissue

• Rib cutters are used to remove the rib

• Underlying pleura carefully incised and lung protected with a chest pack

• Rib spreader is positioned to optimise exposure

• Posterior pleura incised and plane developed between segmental blood supply

   

   

   

   

  Figure 4.7 Posterior scoliosis correction.

   

• Segmental blood vessels may be tied, cauterised or preserved

• Discs are incised and removed piecemeal

• Cartilaginous end plates are removed (aiding fusion)

• Thoracic corpectomy

  • Discs above and below the vertebra in question are removed

  • Vertebral body is cut and removed piecemeal

  • Implant positioning

• Closure

  • Chest drain insertion

  • Chest wall closed in layers

  • Superficial closure

    Postoperative care

• Neurovascular observations and analgesia

• Postoperative haemoglobin and renal function

• No spinal precautions – mobilise as pain allows

• Postoperative chest and spine X-rays

   

  Lumbar spine‌

  Posterior lumbar surgery Microdiscectomy Indications

• Acute disc prolapse symptomatic following 6 weeks non-operative measures

• Earlier surgery if

  • Features of cauda equina syndrome

  • Neurological deficit

  • Intractable pain

    Risks

• Nerve root injury: 1%

• Epidural haematoma

• Dural tear: 5%

• Infection: 1%–2%

• Wrong level surgery: Less than 1%

• Cauda equina: 0.01%

• Dural tear

• Ongoing pain

• Post-discectomy instability leading to lower back pain

• Blindness

  Operative planning

• Full history and physical examination

• MRI lumbar spine

• Plain X-ray lumbar spine

  • Useful for assessing transition levels in lumbar sacral spine

     

     

     

    T3

     

    T7

     

    L4 S2

     

     

     

    Figure 4.8 Anatomical levels in the lumbar spine.

     

    Surgical procedure

• General anaesthesia

• Positioning

  • Prone on Montreal mattress, Wilson frame, or Jackson table

  • ‘Knees-to-chest’ prone position

• Skin prep

• Level check

  • Needle into estimated level

  • Cross-table lateral radiograph

  • Needle adjusted until inserted onto spinous process of correct level

• Midline incision

• Dissection

  • Fat, fascia

  • Diathermy used to dissect the musculature off the posterior elements of the spine

  • Soft tissue swept laterally using a Cobb elevator

• Identification of landmarks

  • Lamina of vertebra above

  • Inferior edge delineated

• Ligamentum flavum identified and incised

• Level check recommended

• Development of interlaminar window

  • Important not to remove more than one-third of facet so as not to develop instability

• Careful exposure of dura

   

• Identification and protection of nerve root

  • Using nerve root retractors

• Incision of posterior longitudinal ligament

  • If intact; with large disc prolapses, disc will have ‘broken through’ this layer

• Incision of disc and piecemeal removal

• Washout with saline

• Closure in layers

• Skin closure

  Postoperative care

• Adequate analgesia

• No spinal precautions

• Postoperative neurological examination

  Posterior lumbar decompression +/− fusion

  Indications

• Lumbar spine trauma

• Spondylolisthesis

• Spinal stenosis

• Degenerative deformities

  Risks

• Nerve injury: 1%

• Cauda equina injury: 0.1%

• Infection 1%–2%

• Venous thromboembolism: 1%

• Persistence/worsening of symptoms: 5%–10%

• Non-union: 5%

• Dural tear

   

   

   

   

   

  Figure 4.9 The knees-to-chest position for lumbar discectomy.

   

  Operative planning

• Full history and physical examination

• Plain X-rays

  • Deformity evaluation

  • Baseline for levels intraoperatively

• MRI lumbar spine

• Single-photon emission computed tomography lumbar spine

• Anaesthetic and medical optimisation

   

  Surgical procedure

• General anaesthesia

• Prone position

  • Montreal mattress or Jackson frame

  • Pressure area padding

• Skin prep

• Level check

  • Needle into estimated level

  • Cross-table lateral radiograph

  • Needle adjusted until inserted onto spinous process of correct level

• Midline incision

• Dissection

  • Fat, fascia

  • Diathermy used to dissect the musculature off the posterior elements of the spine

  • Soft tissue swept laterally using a Cobb elevator

• Identification of landmarks for instrumentation/pedicle entry points

  • Pars

  • Junction of the transverse process and facet

  • Continue soft tissue dissection until transverse process clearly seen

• Level check

• Pedicle screw insertion

  • At the confluence of the pars, transverse process and facet

• Rod application

• Decompression

  • Laminectomy

  • Burr and osteotome

  • Nerve roots identified and explored

  • Undercutting facetectomy

    • Ensure nerves are decompressed both in lateral recesses and foramen

• If dural leak occurs (5%)

  • Repair using 5.0 Prolene

  • Blood, fascia or fat patches

  • Dural ‘glues’

  • Maintain supine for 48 hours postoperatively

• Closure in layers

   

  Postoperative care

• Adequate analgesia

• Neurological observations and formal neurological assessment

• No spinal precautions

   

  Transforaminal lumbar interbody fusion and posterior lumbar interbody fusion

  Indications

• Isthmic and degenerative spondylolisthesis

• Discogenic back pain

• Post-discectomy pain syndromes failing conservative management

   

  Risks

• Nerve injury

• Infection

• Pseudarthrosis

• Persistence of symptoms following non-operative management

   

  Operative planning

• Full history and physical examination

• X-ray

• MRI

   

  Surgical procedure

• General anaesthesia

• Prone position

• Montreal mattress, Jackson table, four-poster frame

• Midline incision

• Dissection

  • Fat, fascia

  • Diathermy used to dissect the musculature off the posterior elements of the spine

  • Soft tissue swept laterally using a Cobb elevator

    • Unilaterally – transforaminal lumbar interbody fusion (TLIF)

    • Bilaterally – posterior lumbar interbody fusion (PLIF)

• Identification of landmarks

  • Transverse processes

• Pedicle screw insertion

• Resection of superior and inferior articular processes of identified facet joint (TLIF) or laminotomy (PLIF)

• Exposure of disc

  • Ensure haemostasis of epidural veins running superior to the pedicle in the neuroforamen

• Piecemeal disc removal

   

• Cartilaginous endplate removal

• Cage insertion +/– bone graft

• Rod application (under slight compression)

• Closure in layers

   

  Postoperative care

• Adequate analgesia

• Neurological observations and formal neurological assessment

• Postoperative X-rays

• No spinal precautions

   

  Minimally invasive spinal surgery

  New, less invasive techniques have and are continually developed in relation to the above procedures due to technological advances in access instrumentation and visualisation, as well as a desire to reduce approach-related comorbidities.

  Indications

• Degenerative disc diseases

• Spinal stenosis

• Trauma

• Curvatures

• Pseudoarthrosis

• Tumour

   

  Risks

• Increased operative length

   

  Operative planning

• Full history and physical examination

• Spinal imaging

  • Plain X-rays

  • CT spine

  • MRI spine

     

    Surgical procedure

• General anaesthetic

• Prone position

• Sterile prep and drape with fluoroscopy/navigation system

• Approach consists of multiple

  • Stab incision at desired angle from midline

  • Guidewire to posterior elements of spine

  • Sequential dilators or pedicle screw guide

    • Guidewire removed after first dilator to prevent advancement

  • Dilated retractor allows adequate visualisation of bony elements for decompression, discectomy, etc.

     

    Anterior lumbar surgery Anterior lumbar interbody fusion Indications

• Degenerative disk disease

• Discogenic disk disease

• Revision of failed posterior fusion

  Risks

• Approach-related complications

  • Retrograde ejaculation

  • Vascular injury

  • Visceral injury

• Infection

• Persistent pain

  Operative planning

• Full history and examination

• Comprehensive surgical history (previous abdominal surgery)

• Plain X-rays

• MRI

  Surgical procedure

• General anaesthetic

• Supine position

• Incision

  • Pfannenstiel

  • Paramedian

  • Lower midline

     

    Ascending articular process

     

    Descending

    articular process of proximal vertebra

    Cauda equina

    Spinal nerve

    Herniated disc

    Posterior longitudinal ligament

    (with overlying veins)

     

     

     

    Figure 4.10 The operative view in lumbar discectomy.

     

• Retroperitoneal dissection

• Identification of

  • Iliac arteries and veins

  • Aortic bifurcation

  • Vena cava

• Mobilisation of great vessels

  • Allows greater exposure of disc space

• Ligation of midline tributaries

  • L4-L5 – iliolumbar and segmental vessels

  • L5-S1 – midline sacral vessels

• Débridement of anterior longitudinal ligament at desired level and exposure of disc space

• Incision into disc with subsequent discectomy

• Exposure to ventral dura

• Interbody cage insertion +/− bone graft

• Closure in layers

  Postoperative care

• Adequate analgesia

• Neurological observations

• Postoperative X-rays

• No spinal precautions – sit to any angle and mobilise as tolerated

 

 

Viva questions‌

1. Describe the relevant surgical landmarks when planning an anterior approach to the T10 vertebral body.

2. What are the indications for performing an anterior approach to the spine?

3. Describe where the segmental blood supply of the vertebral body lies in relation to the disc.

4. At what level of the thoracic spine does the inferior border of the scapula lie when the arms are by the sides? Where, in relation to the spinous process, does the corresponding pedicle of the same vertebra lie?

5. Describe what steps you would take to minimise wrong level surgery in the thoracic spine.

6. What role do chest drains have in thoracic spinal surgery?

7. What factors are involved in selecting patients for scoliosis surgery?

8. Give a brief account of the preoperative management of a patient due to undergo scoliosis surgery.

9. Describe the positioning and the peripheral nerves at risk from prone positioning of a patient.

10. Which nerve runs in the lateral recess at the L5-S1 level?

 

1. Describe your intraoperative and postoperative management of a dural tear.

2. What might be the presentation and management of an acute epidural haematoma?

3. Describe the approach for a lumbar discectomy.

4. What nerve root would be compressed by an L4-L5 far lateral disc?

5. An L4-L5 left-sided paracentral disc protrusion will impinge on which nerve root?

6. What is the incidence of nerve root injury with a discectomy?

7. Describe the orientation of the facet joints at different levels of the spine.

8. Following temporary success of facet blocks, which other radiological procedure can be performed with potential for longer-lasting benefit?

9. Which nerve root leaves the spinal canal via the L4-L5 foramen?