Pocket Atlas of

Spine Surgery

Kern Singh

Alexander R. Vaccaro

Pocket Atlas of Spine Surgery

Pocket Atlas of Spine Surgery

Kern Singh, MD

Assistant Professor

Department of Orthopaedic Surgery

Rush University Medical Center

Chicago, Illinois

Alexander R. Vaccaro, MD, PhD

The Everrett J. and Marion Gordon

Professor of Orthopaedic Surgery

Professor of Neurosurgery

Co-Director, Delaware Valley

Spinal Cord Injury Center

Co-Chief, Spine Surgery

Co-Director, Spine Surgery

Thomas Jefferson University

The Rothman Institute

Philadelphia, Pennsylvania

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Library of Congress Cataloging-in-Publication Data

Singh, Kern.

Pocket atlas of spine surgery / Kern Singh, Alexander R. Vaccaro.

p. ; cm.

ISBN 978-1-60406-308-0 (alk. paper)

I. Vaccaro, Alexander R. II. Title.

[DNLM:

1. Spine—surgery—Atlases.

2. Spine—surgery—Handbooks. WE 17]

617.471--dc23

2011040811

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Some of the product names, patents, and registered designs referred to in this book are in fact

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Printed in China

5 4 3 2 1

ISBN 978-1-60406-308-0

I dedicate this book to my father. As I now progress into parenthood, I realize

the sacrifices you made for me. Never ending patience, bountiful amounts of

time, and a dedication to giving me every opportunity to succeed.

K. Singh

This book is dedicated to my one and only true hero, my father, Alexander Vac-

caro, Senior, who to this day I look to for guidance and wisdom in all aspects

of my life.

A. Vaccaro

Contents

Foreword

Preface

I Introduction

Cervical Surgical Positioning

Thoracic and Lumbar Surgical Positioning

II Cervical

Anterior Cervical Diskectomy and Fusion

Anterior Cervical Corpectomy and Fusion

Open Posterior Cervical Foraminotomy

Minimally Invasive Posterior Cervical Foraminotomy

Occipitocervical Fusion

Posterior Cervical Laminectomy and Fusion

Posterior Cervical Laminaplasty with Instrumentation

III Thoracic Spine

Percutaneous Cement Augmentation

Thoracic Pedicle Screw Placement

Minimally Invasive Thoracic Corpectomy

IV Lumbar Spine

Open Laminectomy and Diskectomy

Open Posterolateral Lumbar Fusion

Minimally Invasive Lumbar Exposure

Minimally Invasive Laminectomy

Minimally Invasive Far Lateral Diskectomy

Minimally Invasive Transforaminal Lumbar Interbody Fusion

Mini-Open Pedicle Screw Placement

108

vii

viii

Contents

20 Percutaneous Pedicle Screw Placement

113

21 Extreme (eXtreme) Lateral Interbody Fusion

124

22 Minimally Invasive Lumbar Corpectomy

130

23 Anterior Lumbar Interbody Fusion

134

Foreword

So why would another atlas of spine surgery be needed, one may ask? Well, in

this unique, singularly authored (Singh) and edited (Vaccaro) new pocket atlas,

one will find the most anatomic-specific, approach-centric, consistent mate-

rial on a myriad of the most common spinal surgical techniques I have ever

seen. The innovative manner of providing a clear anatomic description of the

“target spine anantomy,” core to any spinal surgery, within the context of the

surrounding anatomy, as well as the layers of dissection required to get there,

is absolutely brilliant and highly instructive. It produces a nearly three-dimen-

sional anatomic perspective rarely obtained in a textbook, which is important

not only for conventional open surgical techniques, but mini-open, minimally

invasive, and percutaneous procedures as well.

The atlas is organized anatomically into sections on positioning, cervical,

thoracic, and lumbar surgery. Within those sections it covers the most com-

mon spinal surgeries with specific and useful text accompanying the wonder-

ful pictures, intraoperative photos, and drawings. I was especially pleased to

note a constant focus on proper visualization through adequate hemostasis

and precise anatomic relevance to the procedures, as these are two of the most

essential principles to successful spine surgery in my experience. The chapters

can be covered quickly and reflect on the well laid out combination of labeled

illustrations and accompanying text. This atlas avoids having too much irrel-

evant detail and excessive text to detract from the illustrations, which adds to

the optical aesthetics of the material and allows quick and easy learning.

The primary audience for this atlas is obviously the young practicing sur-

geon, along with medical students, residents, and fellows learning spinal sur-

gery. However, with its emphasis (almost 50 percent of the text) on the newer

and challenging techniques of minimally invasive spinal surgery, even senior

surgeons adopting these type of surgeries into their practice would benefit

from the precise and useful material. Additionally, anyone else involved in the

care of spine surgery patients, from the scrub nurse to the preop counseling

nurse or surgeon assistant, would gain valuable insight into these surgeries.

Finally, this atlas would be a tremendous teaching manual for prospective pa-

tients as well.

I congratulate Dr. Singh and Dr. Vaccaro for their efforts on this most practi-

cal and useful atlas.

Lawrence G. Lenke, MD

Jerome J. Gilden Professor of Orthopedic Surgery

Co-Chief of Pediatric and Adult Spinal Reconstructive Surgery

Washington University Department of Orthopedic Surgery

St. Louis, Missouri

Preface

Spinal surgery atlases are abundant, and the myriad of options can overwhelm

any practicing medical professional. However, these atlases tend to be large

and too cumbersome to bring into the operating room.

This atlas was created to serve a much different purpose. Aside from its

most obvious advantage of being extremely pocket-friendly, several other

features make it shine. The illustrations are detailed, providing not only vi-

sualization of the operative field using actual, intraoperative, high-definition

photographs, but also have beautifully illustrated “see through” adjacent anat-

omy. The reader is allowed to visualize the entire surgical field, including the

anatomy that is never “seen” while operating. This translucent view into com-

plex spinal anatomy helps the reader understand the subtleties of technically

demanding techniques such as minimally invasive spinal surgery.

This atlas is thorough, providing detailed anatomic photographs and illus-

trations of the most common surgical techniques, both open and minimally

invasive. Each procedure chosen was carefully selected to highlight the most

common procedures performed by a practicing spine surgeon. In addition,

MIS techniques that are very technically demanding have been incorporated,

which allows the surgeon to understand the surrounding nonvisualized anat-

omy. The artwork allows the reader to become comfortable with the surgery

before setting foot in the operating room. The accompanying text not only

describes the surgical technique, but also offers pearls and tips to help perform

the procedure expeditiously. Common complications are described, as well as

suggestions for their avoidance.

This atlas will serve as a valuable resource not only for orthopedic surgeons,

neurosurgeons, and surgical trainees such as residents and fellows, but also for

physician assistants, nursing staff personnel, and anyone else involved in the

operative care of patients undergoing spinal surgery.

Introduction

1 Cervical Surgical Positioning

■ Anterior Cervical

foam pad

doughnut to

stabilize head

• The head is placed onto a doughnut to maintain its position. A bump or roll

is placed horizontally across the scapulae to allow for gentle extension of the

cervical spine. Care should be taken to avoid hyperextension in patients with

spinal cord compression and myelopathy. Tape is applied to the top of the

shoulders to depress them gently for improved visualization of the lower cervi-

cal segments. A foam pad is placed over the elbows to protect the ulnar nerve.

Introduction

■ Posterior Cervical

• The Mayfield is placed with the pins along the mastoid process and posterior

to the temporal artery and masseter muscle. The pins are typically tightened

to 60-80 psi.

1 Cervical Surgical Positioning

• The table is slightly raised with the head above the feet to allow for venous

drainage.

chest rolls

• The patient is then placed into a prone position with chest rolls and the May-

field locked into the operative position. Flexion of the neck allows for opening

of the spinal canal and easier decompression. A more neutral alignment should

be performed prior to placement of the final instrumentation. The arms are

gently taped with a gentle depression of the shoulders to allow for increased

visualization of the lower cervical segments.

2 Thoracic and Lumbar Surgical

Positioning

■ Anterior Lumbar

• The patient is positioned with his or her arms across the chest. This allows for

the c -arm to be moved cephalad in the field. A lateral c -arm is essential for local-

ization and implant placement.

2 Thoracic and Lumbar Surgical Positioning

bump

• Additionally, the table can be positioned with the head lower than the feet, al-

lowing the abdominal contents to fall away from the operative field.

- A bump may be placed under the sacrum to increase lordosis.

Introduction

■ Lateral Thoracic/Lumbar

axillary

bump

roll

• The patient is positioned on a regular operating room table with a bump un-

derneath the affected level. The patient is also positioned with the operative

site over the break in the bed, allowing the patient to be maximally flexed at

the surgical level.

2 Thoracic and Lumbar Surgical Positioning

bump

• Tape is used to secure the pelvis and the thorax so that flexion can be accom-

plished without movement of the patient on the operating table. The arms are

well padded, and an axillary roll should be placed under the patient to avoid

any brachial plexopathies.

Introduction

■ Posterior Thoracic/Lumbar

ulnar nerve

• For cases that involve a posterior thoracic and lumbar procedure, the Jack-

son table is often preferred. The Jackson table is radiolucent and allows for

the chest and hip pads to be placed independently. The chest pads should be

placed at the level of the manubrium and below the axilla. The hip pads should

be placed just below the anterior superior iliac spine (ASIS). The thigh pads are

often placed immediately below the hip pad. When the chest and thigh pads

are placed this way, it allows the abdomen to hang freely, decreasing venous

bleeding during the surgical procedure. The neck is placed into a neutral posi-

tion, with care being taken to protect the eyes from pressure.

ulnar

nerve

• The arms are placed into a 90-90 position, with a foam pad placed to prevent

compression along the ulnar nerve. The shoulder should not be hyperextend-

ed, thus decreasing the likelihood of impingement of the rotator cuff.

Cervical

3 Anterior Cervical Diskectomy

and Fusion

Tips and Pearls Before You Begin

Anatomic landmarks may aid in the placement of the surgical incision. Typically,

the hyoid bone overlies the C3 vertebral body, the thyroid cartilage overlies the

C4-5 intervertebral disk space, and the cricoid ring overlies the C6 level. Disk

space localization is performed with a radiopaque marker and a lateral radio-

graph. Needles for localization should be placed into the vertebral body and not

the disk space to prevent possible disk degeneration in case the wrong level is

localized.

thyroid

hyoid

cartilage

gland

bone

mandible

sternum

sternohyoid m.

carotid

trachea

artery

vagus nerve

Superficial landmarks include:

• hyoid C3

• thyroid cartilage C4-5

• cricoid C6

II Cervical

C6 transverse

process

C7 transverse

process

thyroid

cartilage

thyroid gland

carotid

sheath

• A horizontal incision is made just medial to the sternocleidomastoid muscle (SCM).

• A decision on a right- or left-side approach should be made based upon sur-

geon comfort.

C6 transverse

C7 transverse

process

thyroid

thyroid gland

cartilage

external

jugular v.

carotid

sheath

• The platysma is divided in line with the skin incision.

• The external jugular vein helps to identify the tracheoesophageal groove.

3 Anterior Cervical Diskectomy and Fusion

thyroid

gland

cartilage

sternohyoid m.

omohyoid m.

carotid

sheath

• The SCM and carotid sheath are retracted laterally.

- The tracheoesophageal complex is retracted medially.

- The recurrent laryngeal nerve lies in the tracheoesophageal groove.

- The cartoid sheath contains:

▫ the internal jugular vein

▫ the cartoid artery

▫ the vagus nerve

II Cervical

thyroid

gland

thyroid

cartilage

sternohyoid m.

omohyoid m.

carotid

sheath

• The longus colli are swept laterally, exposing the superficial disk space.

- The sympathetic chain lies superficial to the longus colli; therefore, retrac-

tors should be placed deep into this muscle.

• A knife or electrocautery device can be used to perform the annulotomy.

recurrent

ascending

laryngeal n.

cervical

artery

C4-C5

disk

C6-C7

disk

vertebral a.

carotid

sheath

carotid sheath

nerve

roots

• Both straight and curved curettes are used to remove the disk material.

• Caspar pins are used to distract the disk space and to improve visualization of

the posterior intervertebral space.

3 Anterior Cervical Diskectomy and Fusion

C4-C5

disk

C6-C7

disk

ascending

cervical a.

vertebral a.

carotid

sheath

vagus a.

nerve

roots

• A microcurette or nerve hook, along with a 1 mm Kerrison rongeur, can be

used to remove the posterior longitudinal ligament.

- A 6-0 angled curette is helpful for getting behind the unciate process.

C4-C5

disk

C6-C7

end plate

disk

ascending

cervical a.

vertebral a.

carotid

sheath

nerve

roots

• A high-speed burr is used for decortication of the end plates.

- The burr is also used to create parallel end plates to improve contact be-

tween the bone graft and the end plate.

II Cervical

vertebral a.

carotid

sheath

nerve

roots

• A trial sizer is placed to approximate the intervertebral space.

vertebral a.

carotid

sheath

nerve

roots

• An appropriately sized bone graft is gently impacted into place.

- The Caspar pins are removed to allow compression across the graft.

▫ Bone wax is placed into the Caspar pin holes to control bleeding.

3 Anterior Cervical Diskectomy and Fusion

ascending cervical a.

vertebral a.

carotid

sheath

C4 nerve

root

• An anterior cervical plate is applied.

- The shortest feasible plate should be used to avoid abutment of the adjacent

disk space.

• Cervical screws that typically measure 12-16 mm are placed through the plate.

• Depending upon the preference of the surgeon, fixed or variable screws may

be used to allow for controlled subsidence.

II Cervical

Potential Pitfalls

The incidence of vocal cord paralysis from recurrent laryngeal nerve injury ranges

from 1% to 11%. Possible etiologies include traumatic division, neuropraxia, com-

pression from postoperative edema, and injury from thermal necrosis. Midline soft

tissue injury to the trachea, esophagus, and pharynx is uncommon. Dysphagia fol-

lowing anterior cervical surgery is common but temporary; it is estimated to occur

transiently in 8% of patients. Simple measures to help reduce the incidence of dys-

phagia include avoiding overzealous retraction of the esophagus, intermittently

relaxing self-retaining retractors during the procedure, and partially deflating the

endotracheal cuff once the cervical retractors are in position. Vascular injuries may

be prevented by avoiding overzealous retraction and by using blunt-edged retrac-

tors. The likelihood of pseudarthrosis may be minimized by performing a meticu-

lous diskectomy and a thorough decortication of the end plates.

4 Anterior Cervical Corpectomy and Fusion

Tips and Pearls Before You Begin

Obtaining proper imaging studies is paramount for optimal surgical treatment.

Careful evaluation of the location and course of the vertebral artery is necessary

to avoid iatrogenic injury. At the time of surgery, complete diskectomies before

resection of the vertebral bodies facilitate assessment of the depth of the vertebral

body as well as the location of the spinal canal. In cases where ossification of the

posterior longitudinal ligament is extremely adherent to the dura, direct resection

can be dangerous. Successful decompression can be performed by removing the

posterior longitudinal ligament on either side of the ossified area and allowing it

to float away anteriorly from the cord (anterior floating technique) without neces-

sitating direct resection. When a corpectomy is performed, a high-speed burr can

be used to resect most of the vertebral body, leaving only a thin rim of posterior

cortical bone. The posterior cortical bone can be removed using either a small

curette or a Kerrison rongeur.

C4-

C5-

disk

C6-C7

vertebral a.

disk

ascending

cervical a.

carotid

sheath

nerve

root

II Cervical

• Before the corpectomy is begun, the disk space above and below the vertebral

body to be resected is clearly exposed.

• The uncovertebral margin is the most reliable reference in determining the lat-

eral extent of the vertebral body resection.

- A Penfield elevator may be used to palpate the transverse process to ensure

that lateral dissection is sufficient.

▫ The vertebral artery lies deeper than the plane of dissection (posterior

middle third of the vertebral body).

C6-C7

disk

ascending

vertebral a.

cervical a.

carotid

sheath

nerve

root

• A Leksell rongeur can be used to remove most of the vertebral body quickly.

4 Anterior Cervical Corpectomy and Fusion

PLL

C6-C7

disk

ascending

cervical a.

carotid

sheath

• A high-speed burr can be used to remove the remaining bone laterally and pos-

teriorly until the posterior longitudinal ligament (PLL) is identified.

- In most cases, an adequate decompression can be accomplished while pre-

serving the PLL, which can then serve to prevent overdistraction from the

interposed graft.

▫ The defect should be widened to the uncovertebral margin to ensure

adequate thecal sac decompression.

II Cervical

recurrent

PLL

laryngeal n.

C6-C7

disk

nerve

roots

ascending

cervical a.

carotid sheath

• Bleeding from the cancellous vertebral body can be controlled with gelfoam or

other thrombotic agents.

• The exposed end plates can be used to determine an appropriate size for the

cage or graft.

• If an expandable cage is used, expansion should be performed with lateral

fluoroscopy to prevent overdistraction.

4 Anterior Cervical Corpectomy and Fusion

C6-C7

disk

vertebral a.

ascending

cervical a.

carotid

sheath

• The bone graft from the corpectomy site can be placed into and around the cage.

- Bone should be saved in non-neoplastic or noninfectious cases.

- In cases of malignancy or infection, bone graft substitute should be utilized.

C6-C7

disk

ascending cervical a.

vertebral a.

carotid

sheath

• A plate can then secure the cage and graft in place.

- Posterior supplementation should be considered in cases of poor bone qual-

ity or in multilevel corpectomies.

II Cervical

• The patient suffered a traumatic C5 burst fracture with neurological deficit.

• An AP/lateral radiograph demonstrating C5 corpectomy (PEEK cage) with an

anterior cervical plate extending from C4 to C6.

Potential Pitfalls

• Iatrogenic injury to the vertebral artery can occur either because of an aberrant

vertebral artery or from excessive lateral decompression.

• Dural tear, spinal fluid leak, or neurologic injury can occur during resection of

the posterior vertebral body and the posterior longitudinal ligament.

• Graft extrusion and hardware failure can occur in cases of prior posterior de-

compressive procedures or multilevel corpectomy; a posterior stabilizing proce-

dure with instrumentation may be necessary to protect the anterior construct

adequately.

5 Open Posterior Cervical Foraminotomy

Tips and Pearls Before You Begin

Intraoperative imaging is mandatory to confirm the correct level of decompres-

sion. The use of anatomic landmarks can be helpful in many cases, but normal

anatomic variants may lead to confusion and ultimately to surgery on the wrong

level. Visualization can be enhanced with an operating microscope or with a com-

bination of loupes and a fiber-optic head light.

spinal

cord

C5 spinous

C6 spinous

process

nerve

IAP

roots

deep cervical

artery

• The inferior articular process (IAP) of the cephalad vertebrae is identified.

II Cervical

spinal

cord

C5 spinous

C6 spinous

process

resected IAP

SAP

C5-C6

of C6

nerve root

• Approximately 35% of the medial portion of the IAP is removed to visualize the

superior articular process (SAP) of the caudal vertebrae.

C6 nerve

root

Kerrison rongeur

resecting C6 SAP

• A Kerrison rongeur or burr can be used to resect the SAP, which overlies the

exiting nerve root.

5 Open Posterior Cervical Foraminotomy

C6 nerve

root

keyhole

foraminotomy

• A keyhole foraminotomy is created with the nerve root visualized.

6 Minimally Invasive Posterior Cervical

Foraminotomy

C1 (atlas)

C2 (axis)

initial

dilator

• A lateral fluoroscopic image is used to identify the level in question.

• An incision is made 0.5 cm lateral to the midline.

6 Minimally Invasive Posterior Cervical Foraminotomy

C1 (atlas)

C2 (axis)

tubular

dilator

• Tubular dilators (18 mm) are used to spread the paraspinal muscles.

C5 nerve

root

IAP of C4

SAP of C5

• The soft tissue is removed, exposing the medial half of the facet joint and the

inferior portion of the superior lamina.

II Cervical

C5 nerve

root

IAP of C4

SAP of C5

• A burr is used to remove the medial third of the inferior articular process (IAP)

of the cephalad vertebrae.

nerve root

exposed

IAP of C4

SAP of C5

(resected)

• The burr is then used to remove the superior articular process of the inferior

vertebrae.

• The nerve root is then visualized exiting into the neuroforamen.

6 Minimally Invasive Posterior Cervical Foraminotomy

Potential Pitfalls

• Excessive retraction or compression of the neural elements may lead to

iatrogenic neurologic symptoms. Persistent postoperative symptoms may be

caused by inadequate decompression.

• Excessive resection of the facet joint may result in increased neck pain and,

possibly, spinal instability.

7 Occipitocervical Fusion

Tips and Pearls Before You Begin

For dual plating, occipital screws should be placed three to a side on either side

of the midline, just below the superior nuchal line and as close to the external oc-

cipital protuberance as possible. An independent occipital plate may require only

two or three screws, usually oriented in a vertical or transverse orientation. Leak-

age of cerebrospinal fluid (CSF) at this stage can usually be stopped by placing a

screw or bone wax into the hole.

occiput

dura

C1 lateral

C2 lateral

mass

• Subperiosteal exposure of the occiput and the C1-C2 vertebral levels is essen-

tial for instrumentation placement.

• The vertebral artery travels along the superior lateral surface of the C1 arch

approximately 1.5 cm from the midline.

7 Occipitocervical Fusion

vertebral artery

occiput

dura

curette

into

foramen

magnum

C2 nerve

root resected

C2 pedicle

lateral

screw start

mass edges

point

• A curette is placed into the foramen magnum to clearly define the inferior bor-

der of the occiput.

occiput

dura

C2 nerve

root resected

lateral

mass edges

• An occipital plate has been applied. Screws are placed bicortically in the

midline.

- The plate is appropriately sized so that it is easier to connect the occipital

and C1-C2 screw tulips.

II Cervical

vertebral artery

occiput

dura

C2 nerve

root resected

C2 pedicle

screw start

lateral

point

mass edges

• The C2 (axis) pedicle screw starting point occurs at the inferior and lateral edge

of the inferior articular process of C2.

- The vertebral artery lies directly anterolateral. The screw should be directed

medial and cephalad to avoid potential vascular injury.

▫ Screws placed bicortically into the anterior axis may risk injury to the in-

ternal carotid artery.

▪ The C2 screw is angled 20° medially and 15-20° caudally (use lateral

flouroscopy).

7 Occipitocervical Fusion

occiput

dura

C2 nerve

root resected

screw tract

probed

• The screw tract is drilled and then probed to ensure that the cortical walls are

not breached.

occiput

dura

C2 nerve

root resected

C2 screw

inserted

• The C2 pedicle screw is inserted.

II Cervical

vertebral artery

occiput

dura

C2 nerve

root resected

C1 lateral

lateral

mass screw

mass edges

start point

• The C1 (atlas) lateral mass screw starting point is inferior to the arch of C1. The

C2 (occipital) nerve root has been resected to facilitate screw placement.

- Resection of the C2 nerve may result in occipital dythesthesias in up to 20%

of patients.

- The ponticulus posticus (Latin for “little bridge to the rear”) refers to a bony

bridge on the atlas that covers the groove for the vertebral artery (also

known as the arcuate foramen). It is a common anatomic variant that is esti-

mated to occur in 3% to 15% of the population.

7 Occipitocervical Fusion

dura

lateral

mass

boundary

vertebral artery

• C1 lateral mass screw placement is shown. Note that the C2 nerve root has

been resected, exposing the C1 lateral mass and C1-C2 facet joint.

dura

lateral

mass

boundary

vertebral artery

• The C1 screw tract is probed. A unicortical screw is placed. Bicortical screws

are dangerous and may encroach upon the internal carotid artery anteriorly.

- The C1 lateral mass screw is aimed 10° medially and 10° cranially (use lateral

flouroscopy).

II Cervical

dura

vertebral artery

• The C1 lateral mass is screw inserted.

Potential Pitfalls

Perpendicular occipital screw placement can be especially difficult due to the

steep angle required close to the foramen magnum. If the occipital bone close

to the foramen magnum is unusually thin or in certain pathologic states, this can

make adequate screw purchase difficult or even impossible. Occipital screw place-

ment at the desired level can be compromised by diseased bone, such as that

found in osteomyelitis or neoplasm. Avoid these problems by placing screws clos-

er to the superior nuchal line, but no more than 20 mm lateral to the midline, and

as far superior to the foramen magnum as feasible. If the desired cervical fusion

levels are too diseased for adequate screw placement, extend the construct infe-

riorly as many levels as necessary. Stabilization must be performed in the neutral

position, as rigid cervical flexion or extension can be extremely distressing to the

patient. Durotomy and neural or vascular injury can occur during drilling, screw

placement, wire passage, or suboccipital craniotomy. A poor fit of the plates or

rods can lead to bony erosion of the lamina or pressure ulcers of the overlying

skin, with subsequent hardware exposure and infection.

8 Posterior Cervical Laminectomy and Fusion

Tips and Pearls Before You Begin

In patients with myeloradiculopathy and significant radicular symptoms, the pres-

ence of foraminal stenosis should be identified on preoperative imaging studies

and appropriate concomitant foraminotomies planned. During preoperative posi-

tioning, excessive flexion or extension should be avoided in myelopathic patients.

For foraminotomies, slight flexion opens the interspaces and foramina, but care

must be taken during dissection, as the dural sac is more susceptible to injury.

The surgical exposure for laminectomy proceeds caudal to cephalad; this facili-

tates subperiosteal detachment of paraspinal muscles, which attach in the same

direction, and reduces bleeding. A clamp is placed on an exposed spinous pro-

cess, and a lateral radiograph is obtained to confirm levels. Dissection should pro-

ceed to the lateral margin of the facet joints. This extent of exposure establishes

the landmarks needed for safe placement of lateral mass screws and ensures that

more than half of the facet joint is not removed during any associated forami-

notomy. Dissection beyond the lateral margin of the facet joint risks significant

bleeding from the soft tissue musculature. Care must be taken to avoid injuring

the facet capsules at any level if a fusion is not planned.

II Cervical

lateral mass

boundaries

vertebral artery

interspinous

ligament

vertebral artery

lateral mass

boundaries

nerve

roots

• A midline posterior approach is utilized, with dissection performed through the

avascular ligamentum nuchae.

• Subperiosteal exposure is performed, extending out to the lateral edge of the

lateral mass.

- Bleeding is typically encountered along the lateral edge of the lateral mass.

- This bleeding can be controlled with bipolar cautery.

8 Posterior Cervical Laminectomy and Fusion

lateral mass

boundaries

vertebral artery

starting

point

vertebral artery

lateral mass

boundaries

nerve

roots

• The lateral mass is exposed and clearly defined, exposing the superior, inferior,

and medial lateral borders.

lateral mass

boundaries

vertebral artery

drill angled

20° cephalad

and lateral

vertebral artery

lateral mass

boundaries

nerve

roots

• Once the lateral mass is defined, the starting point should be created with a

high-speed burr.

- The center of the lateral mass is burred first.

- The drill is then directed 20° cephalad and lateral, thereby avoiding the ver-

tebral artery and nerve root.

II Cervical

screw

holes

vertebral a.

troughs

vertebral a.

nerve roots

• Once the lateral mass screw holes are created, a laminectomy can be performed.

- Two troughs are created with a high-speed burr.

- The troughs are created just medial to the screw start points at the junction

of the lateral mass and lamina.

screw holes

vertebral a.

spinal cord

nerve

roots

• The lamina is then removed en bloc with passage of instruments into the canal.

8 Posterior Cervical Laminectomy and Fusion

lateral

mass screws

rods

cross

spinal cord

connector

• The lateral mass screws are then placed and rods are secured in place. A cross

connector can be applied to increase torsional rigidity.

- The bone graft is placed into the decorticated facet joints.

Potential Pitfalls

A laminectomy accomplishes indirect decompression of the spinal cord by allow-

ing posterior translation of the cord away from the anterior compressive path-

ology. Typically, a minimum of three or four levels is required to allow adequate

cord translation. When a laminectomy is performed for cervical stenosis, instru-

ments with larger profiles than the footplate of a 2 mm Kerrison rongeur should

not be placed underneath the lamina near the central canal, to minimize the risk

of iatrogenic cord injury. Postsurgical C5 palsy occurs in 0.5% of patients and typi-

cally appears between the second and fifth postoperative day. Most cases sponta-

neously resolve over 6 to 12 months.

Foraminal decompression risks nerve root injury, especially if high-profile Ker-

rison rongeurs are placed into the foramen. Air embolus is a rare complication

associated with posterior cervical surgery when the patient is in the seated po-

sition. Its occurrence can be monitored with the use of end tidal CO₂ sensors.

If a significant air embolism is suspected, the patient should undergo immedi-

ate electrocauterization of any readily accessible bleeding veins, and the wound

should be quickly covered. If a central venous catheter was placed preoperatively,

the line can be advanced into the right atrium to attempt evacuation of the air.

If this fails, the patient can be placed in the left lateral decubitus position to trap

the air in the right atrium.

9 Posterior Cervical Laminaplasty with

Instrumentation

Tips and Pearls Before You Begin

Incise the nuchal ligament and paracervical muscles at the exact midline, and

strip the muscles subperiosteally to avoid bleeding. Be careful not to strip or

expose the cervical facet capsules. Complete the hinge side gutter last, after

completion of the open side gutter and the resection of the ligamenta flava at

both ends of the laminar door. Check the stability of the hinge frequently while

making the hinge gutter. Preserve the spinous process of C7 whenever possible

to reduce postoperative axial symptoms. Encourage early active range of motion

of the neck.

facet

capsules

vertebral a.

nerve

roots

• A midline posterior cervical exposure is performed.

• Care is taken not to strip the facet capsule.

• Only the medial portion of the lamina/facet junction is exposed.

9 Posterior Cervical Laminaplasty with Instrumentation

facet

joint

C3 spinous

process removed

vertebral

artery

nerve

roots

• Once exposed, the spinous processes from C3-C7 are removed.

facet

joint

epidural veins

vertebral

hemostatic

artery

sealant

nerve

roots

• Once the spinous processes are removed, bone wax or a hemostatic sealant is

applied to control bone bleeding.

• The junction between the lamina and facet is identified.

II Cervical

epidural veins

vertebral a.

dura mater

3 mm trough created at

laminar/facet junction

nerve roots

• A burr is used to create an opening of approximately 3 mm.

• This opening requires the removal of 15% of the facet joint.

vertebral

artery

dura mater

epidural

vein exposed

• Once the opening is through the lamina, the epidural veins overlying the dura

are visualized.

• A curved microcurette can be used to palpate the defect to ensure that the

trough is through the bone.

9 Posterior Cervical Laminaplasty with Instrumentation

unicortical

trough

spinal

cord

epidural veins

facet joint

nerve

roots

• Once the first trough is complete, a similar trough is created on the other side

(hinge side).

• However, the hinge side trough is only unicortical.

unicortical trough

acts as “hinge”

lamina opened

to decompress

spinal cord

vertebral a.

epidural veins

nerve

roots

• A straight curette allows the lamina to be gently opened like a door.

• The spinal cord is then gently decompressed and allowed to float back dorsally

once the lamina are opened.

• Small 10-14 mm craniofacial plates are applied on the opening side.

II Cervical

1 screw into lamina;

2 screws into facet

• The plates are secured with 5 mm screws.

- Two are fastened into the lateral mass.

- One is fastened into the lamina.

• The plate secures the lamina in an expanded state, decompressing the spinal

cord.

Potential Pitfalls

• Detachment of the hinge may occur due to excessive burring. Fracture of the

hinge may occur due to inadequate burring and excessive opening force.

• Segmental motor paralysis, particularly at the C5 and C6 segments, occurs in

approximately 0.5% of patients.

• Postoperative axial neck pain and limited cervical range of motion may be re-

lated to excessive stripping of the paraspinal muscle off the facet capsules.

• Closure of the opened laminae may occur with inadequate fixation.

III

Thoracic Spine

10 Percutaneous Cement Augmentation

Tips and Pearls Before You Begin

The use of biplanar fluoroscopy greatly aids in cannula insertion and cement injec-

tion. The lateral image is brought over the top or under the bed, with the arc lean-

ing away toward the head. The anteroposterior (AP) image is brought in diago-

nally, with the image intensifier directly over the target site. It is most convenient

to obtain the true AP image first, because the diagonal entry makes this process

challenging. The lateral image is then adjusted around the AP image.

Treatment of multiple levels can be performed with a single batch of cement.

The cement is stored in a sterile ice water bath to slow the polymerization pro-

cess. With vertebroplasty, all the cannulas are inserted first, and then each site

is injected sequentially. With kyphoplasty, the first site is drilled, the balloon

tamp deployed, and the cement injected. The limit on the number of levels is

dictated by the cement load. The risk of cement toxicity increases with the num-

ber of levels treated. As a general rule, no more than three levels are treated in

one operation.

Special consideration related to cement fill is needed for kyphoplasty. Along

with the cement required for filling the void created by the balloon tamp, addi-

tional cement is needed to allow integration of the cement into the surrounding

trabecular bone. This serves to lock in the cement. Inadequate filling may lead to

further collapse of the surrounding bone from excessive motion at the interface

between the bone and cement. In general, the volume of cement injected should

be greater than the volume of the inflated balloon.

Maintenance of the reduction via kyphoplasty may be difficult in certain frac-

tures, particularly in vertebrae plana. Once the balloon is deflated, the fracture

may collapse again. The reduction can be maintained by the eggshell technique.

A small amount of cement (0.5 to 1 cc) is injected into the cavity. The balloon

tamp is reinserted and gently reelevated. The small cement bolus is then spread

around the balloon to create a thin eggshell of cement. When the balloon is re-

moved, the eggshell mantle holds the reduction until the remainder of the ce-

ment is injected.

III Thoracic Spine

AP c - arm

lateral

c-arm

head

foot

• Biplanar fluoroscopy is used throughout the procedure.

10 Percutaneous Cement Augmentation

L1 vertebral

body

L2 vertebral

body

L3 vertebral

body

cannulas placed into

L3 vertebral body

• The starting position for the cannula should be at the 10 o’clock or 2 o’clock posi-

tion of the pedicle (superior-lateral corner depending upon the left or right side of

the spine). This position places the cannula the farthest from the exiting nerve root.

The cannula is advanced such that on the AP side it never crosses the medial edge

of the pedicle until it crosses the posterior verterbral body line on the lateral image.

cannula enters

vertebral body

through pedicle

facet

joint

L3 transverse

process

pedicle

L3 body

• The cannula is started lateral to the facet joint, thereby avoiding any damage

to the facet capsule.

III Thoracic Spine

cannulas placed into

L3 vertebral body

posterior

L1 vertebral

body

L2 vertebral

body

balloons inflated,

restoring L3

vertebral height

• Fluoroscopy is used to confirm that the balloon is in the anterior portion of the

vertebral body, so that no bone can be retropulsed into the spinal canal.

10 Percutaneous Cement Augmentation

L3 body

• The balloon is then inflated to create a potential space for cement augmentation.

III Thoracic Spine

cannulas placed

into L3

bone cement

injected into

cavities in

posterior

restored L3

• Cement is then added to the vertebral body under fluoroscopic visualization.

The cement is carefully observed on both the AP and lateral images so that the

borders of the vertebral body are not violated. If cement extravasation is noted,

the procedure is terminated. Cement should be avoided in the posterior aspect

of the vertebral body.

10 Percutaneous Cement Augmentation

L1 vertebral

body

L2 vertebral

body

balloons removed, residual

cavities filled with bone cement

• Ideally, cement filling should cross the midline in the AP plane.

Potential Pitfalls

• poor fluoroscopic visualization due to severe osteoporosis

• cement embolization

• cement extravasation into the neuroforamina or spinal canal

• pedicle fracture due to improper cannula insertion

• inadequate cement fill

11 Thoracic Pedicle Screw Placement

Tips and Pearls Before You Begin

Meticulous dissection with exposure of the transverse processes is mandatory.

Facetectomies should be performed at each fusion level, and the cartilage should

be removed. Fluoroscopy or intraoperative radiographs can be used to identify

the pedicle shadow. The most important anatomic landmark is the middle of the

facet, as the pedicle screw start point should always be lateral to this midpoint.

pedicles

ribs

• Meticulous dissection should be performed with the inferior 3-5 mm of the

inferior facet osteotomized. The base of the superior articular process is a key

landmark for entry into the pedicle. The starting point for each thoracic screw

varies. Biomechanically, it is best to place the screws parallel to the superior

end plate. When the procedure is started distal at T12, there is a trend toward

a more medial and cephalad pedicle starting point as one proceeds toward the

midthoracic region (T7-T8). Proximal to this point, the starting point moves

more lateral and caudad as one proceeds to the upper thoracic spine.

11 Thoracic Pedicle Screw Placement

pedicles

ribs

• A burr may be used to create a pedicle blush by removing only the dorsal cor-

tex in the area of the targeted pedicle entry point.

pedicles

ribs

• Pedicle blush refers to bleeding that arises from the vertebral body into the

pedicle start point.

III Thoracic Spine

pedicles

ribs

• With gentle but firm ventral pressure, the gear shift should be easily wiggled

into the pedicle. If any amount of significant resistance is met, the surgeon

should reevaluate the starting point and trajectory of the pedicle. The gear

shift should be advanced approximately 30-35 mm.

pedicles

ribs

• The surgeon then probes the pedicle hole to feel for the medial, lateral, supe-

rior, inferior, and ventral walls of the pedicle. Most pedicle violations occur at the

junction of the pedicle and vertebral body (15-20 mm).

11 Thoracic Pedicle Screw Placement

• The screw is then appropriately sized and positioned. Typical screw lengths in

the lower thoracic spine average 40-45 mm, while in the upper thoracic spine

lengths may be as short as 35 mm.

Potential Pitfalls

• Pedicle violation medially or inferiorly may occur and result in nerve root or

spinal cord injury.

• Anterior cortex violation from screws that are too long may result in vascular

or visceral injury.

• Pedicle screw pullout or failure of fixation may occur with malpositioned ped-

icle screws.

12 Minimally Invasive Thoracic Corpectomy

Tips and Pearls Before You Begin

Care should be taken to obtain orthogonal fluoroscopic views of the involved ver-

tebral level. Parallax may result in exposure of the incorrect verterbal body and

improper dilator placement along the anterior vertebral body, risking damage

to the great vessels. Blunt dissection is necessary to prevent perforation of the

pleura. A sponge stick or peanut can be used to sweep the pleura anteriorly. If the

pleura is violated, then a chest tube or red rubber catheter can be placed upon

completion of surgery. In general, most patients are asymptomatic, and prompt

removal of the catheter will allow rapid mobilization.

intercostal nerves

T11

T10-

T9-

T11

T12

T10

disk

T10

lung

spinous processes

• Rib exposure. The anterior and posterior margins of the vertebral body to be

resected are marked using fluoroscopy. The overlying rib is subperiosteally

exposed.

12 Minimally Invasive Thoracic Corpectomy

intercostal nerves

rib released of

neurovascular

bundle

T11

T10-

T9-

T11

T12

T10

disk

T10

lung

spinous processes

• The inferior portion of the rib is subperiosteally released from the neurovascu-

lar bundle.

intercostal nerves

cut edge

of 10th rib

T11

T10-

T11

T9-

lung

disk

T10

disk

T12

T10

spinous processes

• Approximately two centimeters of rib have been resected. The pleura of the

lung is visualized.

III Thoracic Spine

lung

retracted

anteriorly

intercostal

nerves

T10

T11

T12

junction of

10th rib and

T10 transverse

process

• A series of tubular dilators are placed into the defect, sweeping the lung and

pleura anteriorly and resulting in an extrapleural exposure of the vertebral

body.

12 Minimally Invasive Thoracic Corpectomy

vena cava

T9-

T10-

T10

T11

disk

T10

lung

10th rib

(resected)

intercostal

nerves

• The intervertebral disk space above and below the involved vertebral level is sub-

periosteally exposed. The segmental artery has been cauterized and resected.

vena cava

10th rib

(cut)

wall of T10

T11

PLL

spinal canal

10th rib

(cut)

intercostal nerves

• The corpectomy has been completed using a high speed burr. The anterior

vertebral body wall has been thinned and preserved while the T9-T10 and

T10-T11 disk spaces have been resected. The spinal canal has been exposed,

preserving the posterior longitudinal ligament.

III Thoracic Spine

vena cava

10th rib

(cut)

wall of T10

plate

on T9

on T11

spinal canal

10th rib

(cut)

intercostal nerves

• An expandable titanium cage has been appropriately sized and placed into the

defect. A plate has been placed into the vertebral body above and below at the

T9 and T11 levels, respectively.

vena cava

10th rib

(cut)

10th rib

(cut)

intercostal nerves

• A dual rod construct has secured the T9 and T11 levels.

12 Minimally Invasive Thoracic Corpectomy

Potential Pitfalls

Adequate radiographic visualization is important. Improper docking of the dilator

too far anteriorly may result in resection of the anterior longitudinal ligament

with potential implant migration or damage to the great vessels. The segmental

vessel can typically be cauterized. In situations where it continues to bleed, hemo-

static agents and pressure will cause the bleeding to cease.

Lumbar Spine

13 Open Laminectomy and Diskectomy

Tips and Pearls Before You Begin

The ligamentum flavum is often hypertrophied as part of the pathologic process.

In the hypertrophied state, it can become a visual barrier to precise identification

of anatomic structures and may pose a physical impediment to safe entry into the

spinal canal. To obviate these problems, excise the superficial layers of the liga-

mentum separately. A plane of dissection can be found at the lower attachment

of the ligamentum to the top surface of the inferior lamina. The primary connec-

tion of the ligamentum is fixed to the leading surface of the inferior lamina. A

hypertrophied ligamentum will generally expand posteriorly and mushroom up

over the posterior, flat face of the lamina. Careful dissection with a small 2-0 or

3-0 curette, with the blunt aspect against the flat of the inferior lamina, usually

defines the superficial layer for removal. The remaining deep ligamentum can

then be excised. Always release the attachment of the deep layer from the under-

surface of the superior lamina first (with the ligamentum still under tension). A

small curette is used to sweep under the lamina. This minimizes the risk of dural

tear. Releasing the inferior attachment first would slacken the ligament and re-

quire blind grasping under the superior lamina to remove the upper ligamentum.

Blind use of a rongeur increases the risk of dural tears.

If the interlaminar space requires enlargement, this is best done with a side-

cutting burr. To prevent dural compromise, keep the angle of the burr perpendic-

ular to the dura so the noncutting tip is adjacent to vital structures. A horizontal

sweeping motion is used, and an inward push is avoided. Take care to preserve

the pars interarticularis (7-9 mm minimum). Bites from a Kerrison rongeur may

produce stress fractures in the pars.

IV Lumbar Spine

■ Skin Incision

supraspinous

ligament

L5 spinous

L4 spinous

L3 spinous

process

dura

traversing L5

L5 lamina

nerve root over

disk herniation

L3-L4 facet

L4-L5 facet

joint

L5-S1 facet

joint

exiting nerve

roots

• A midline incision is used over the levels that are to be resected.

supraspinous

ligament

L4 spinous

L3 spinous

L5 spinous

process

dura

traversing L4

nerve root

L3-L4 facet

L4-L5 facet

joint

L5-S1 facet

joint

exiting nerve

roots

• The fascia is clearly identified prior to incision.

13 Open Laminectomy and Diskectomy

supraspinous

ligament

L4 spinous

L5 spinous

L3 spinous

process

dura

L3-L4 facet

joint

L5-S1 facet

joint

exiting nerve

roots

• The fascia is then identified and opened in the midline over the spinous pro-

cess. Subperiosteal dissection is accomplished with a Cobb elevator.

L5-S1 facet

joint

L3-L4 facet

joint

supraspinous

ligament

L5 spinous

L4 spinous

L3 spinous

process

dura

lamina

L5-S1

traversing L5

disk space

nerve root over

disk herniation

L3-L4

disk space

• The laminae are exposed to the medial edge of the facet capsule.

IV Lumbar Spine

L5-S1 facet

joint

L4-L5 facet

joint

L3-L4 facet

joint

L5 spinous

process

traversing L5

nerve root over

disk herniation

• The inferior half of the L4 and superior half of the L5 spinous processes are

removed along with the supraspinous and interspinous ligaments.

L5-S1 facet

joint

L4-L5 facet

joint

L3-L4 facet

joint

inferior half

lamina

superior half

of L5 spinous

lamina

of L4 spinous

process

ligamentum

process

flavum

traversing L5

nerve root over

L3-L4

disk herniation

disk space

• A Kerrison rongeur is used to remove the ligamentum flavum.

13 Open Laminectomy and Diskectomy

L5-S1 facet

joint

L4-L5 facet

joint

L3-L4 facet

joint

inferior remnant

superior remnant

lamina

of L5 spinous

of L4 spinous

process

dura

L3 spinous

process

L3-L4

disk space

• The lateral recess is decompressed by undercutting the superior articular pro-

cess of the inferior vertebra.

L5-S1 facet

L4-L5 facet

joint

L3-L4 facet

joint

inferior remnant

superior remnant

of L5 spinous

lamina

of L4 spinous

process

dura

traversing L5

nerve root

disk

herniation

• The traversing nerve root is gently retracted medially exposing the underlying

disk herniation. The dura and the traversing nerve root are exposed.

IV Lumbar Spine

L5-S1 facet

joint

L4-L5 facet

joint

L3-L4 facet

joint

inferior half

lamina

superior half

of L5 spinous

of L4 spinous

process

L3 spinous

dura

process

traversing L5

nerve root

retracted medially

disk

herniation

• A knife is used to make an annulotomy over the disk herniation.

L5-S1 facet

joint

L4-L5 facet

joint

L3-L4 facet

joint

inferior half

lamina

superior half

of L5 spinous

of L4 spinous

process

dura

L3 spinous

process

traversing L5

nerve root

extracted medially

L3-L4

disk space

L4-L5 disk

disk

space

fragment

• The disk fragment is removed with a pituitary rongeur.

13 Open Laminectomy and Diskectomy

Potential Pitfalls

If surgery is performed at the wrong level, it is usually done at the segment above

the intended operation. If there is any question of the expected pathology not

being found, additional confirmatory imaging should be performed to establish

levels prior to incising the annulus.

14 Open Posterolateral Lumbar Fusion

Tips and Pearls Before You Begin

In the lumbar spine, the pedicles are medially oriented, particularly in the lower

lumbar segments. A lateral fluoroscopic image obtained for purposes of local-

ization is extremely helpful in determining cephalad/caudad orientation of the

pedicle. In general, the L3 pedicle is directed straight vertically toward the floor,

with the upper lumbar segments angulated toward the head and the lower lum-

bar levels directed toward the foot. If a pedicle cannot be cannulated, a hemilami-

notomy can be performed, palpating the medial wall to determine angulation.

L3 spinous

L4 spinous

L5 spinous

process

L4 pedicle

• The initial exposure should involve subperiosteal dissection of the muscle to

the facet joint.

14 Open Posterolateral Lumbar Fusion

L4 spinous

L3 spinous

process

pedicle

L4-L5 facet

joint

transverse

process

• Resection of the facet capsule and exposure of the superior articular process

(caudad vertebra) and the transverse process is essential to identify the start-

ing point for the lumbar pedicle screw.

L4 spinous

L3 spinous

process

mamillary

process

transverse

process

L4-L5 facet

pedicle

joint

• Pedicle start point. The transverse process is bisected, and the mamillary pro-

cess is identified at the junction of the inferolateral corner of the facet joint.

IV Lumbar Spine

L4 spinous

L3 spinous

process

lateral edge

of pars inter-

articularis

L4-L5 facet

pedicle

joint

transverse

process

• The pars interarticularis is used to identify the medial extent of the pedicle.

L4 spinous

L3 spinous

process

L4-L5 facet

pedicle

joint

transverse

process

• The gear shift is advanced with gentle pressure and slight medial angulation.

14 Open Posterolateral Lumbar Fusion

L4 spinous

L3 spinous

process

L4-L5 facet

pedicle

joint

transverse

process

• The four walls of the pedicle are probed.

L4 spinous

L3 spinous

process

L4-L5 facet

pedicle

joint

transverse

process

• The pedicle tract is tapped.

IV Lumbar Spine

L4 spinous

L3 spinous

process

L4-L5 facet

joint

transverse

process

• The pedicle screw is placed.

Potential Pitfalls

During exposure, bleeding typically occurs along the lateral aspect of the facet

joint and the lateral edge of the pars interarticularis. These segmental arteries

should be prophylactically cauterized with bipolar cautery; otherwise, undue

time is spent obtaining hemostasis. Pedicle wall violations typically occur at the

pedicle-vertebral body junction (15-20 mm in depth). If a violation occurs, the

starting point of the screw can be lateralized and the angulation of the screw can

be adjusted.

15 Minimally Invasive Lumbar Exposure

Tips and Pearls Before You Begin

Radiographic visualization is extremely important both in the anteroposterior

(AP) and lateral views. Often, the initial dilator can be used as a Cobb elevator,

with gentle subperiosteal dissection being performed to sweep the paraspinal

muscle off the lamina. Anatomic landmarks may be difficult to conceptualize as

the surgeon adapts to the minimally invasive technique.

spinous

processes

midline

L5 traversing

nerve root

lamina

L5 exiting

nerve root

L5 pedicle

L4 pedicle

L4-L5

disk space

L3 exiting

L4 exiting

nerve root

• By use of an AP fluoroscopic image, key bony landmarks are identified:

- midline (spinous processes)

- pedicular line (lateral edge of the pedicle)

▫ vertical

▫ horizontal

- skin incision line

▫ For laminectomies, the incision is made closer to the midline.

▫ For fusions, the incision is made lateral to the midpedicular line (1.0 cm).

- The size of the skin incision is dependent upon the size of the final working

portal (15-26 mm).

IV Lumbar Spine

midline

traversing L5 root

erector spinae muscle

under L4 lamina

L4 pedicle

targeted

lamina

L4-L5 facet

joint

L5 exiting

nerve root

L5 pedicle

L4-L5

L4 exiting

disk space

nerve root

• An initial dilator is used to localize the disk space to be prepared using a lateral

fluoroscopic image.

15 Minimally Invasive Lumbar Exposure

midline

targeted L4-L5

traversing L5 root

facet joint

under L4 lamina

erector spinae muscle

L4 pedicle

lamina

exiting L5

nerve root

exiting L4

L5 pedicle

nerve root

• The dilators are sequentially increased in size, thereby increasing the size of the

working portal.

- The dilators should be gently swept to remove any intervening muscle and

soft tissue.

IV Lumbar Spine

midline

tube retractor

traversing L5 root

over L4-L5 facet

under L4 lamina

L4 pedicle

lamina

exiting L5

nerve root

L5 pedicle

exiting L4

nerve root

• The final portal is established and firmly connected to the surgical bed.

• A lateral fluoroscopic image is obtained to confirm localization of the disk

space to be prepared.

Potential Pitfalls

Inadequate or incorrect retractor placement will lead to incomplete decompres-

sion and fusion procedures. Radiographic visualization can help confirm and ori-

ent the surgeon when visualization of the anatomy is difficult due to bleeding or

incorrect positioning of the retractor.

16 Minimally Invasive Laminectomy

Tips and Pearls Before You Begin

Proper patient positioning and good intraoperative imaging are essential. For the

given procedure, it is also important to choose the correct size for the retractor. For

a decompression, a smaller diameter retractor is required to allow placement medial

to the facet joint. Once the retractor is in the correct position, resist the tempta-

tion to move it often because such movement leads to creep of the muscle into the

wound.

If there is an incidental durotomy, it should be treated in a similar fashion to the

same complication encountered in an open procedure. A primary suture repair is

preferable if it is possible.

Epidural bleeding needs to be proactively controlled. There are several ways to

reduce the likelihood of problematic bleeding. First, positioning of the patient on the

Jackson frame reduces intra-abdominal pressure. When in the epidural space, find the

bleeders before they find you and use bipolar electrocautery. Liberally use a throm-

botic paste product to minimize bleeding.

midline

L5 spinous

process

L5-S1

disk

space

L4 lamina

pars inter-

lamina

articularis

L5 pedicle

L3-L4

L4-L5 facet

facet joint

L5-S1 facet

joint

L3-L4

disk

space

L4-L5 disk

L4 pedicle

space

• Exposure of the hemilamina.

IV Lumbar Spine

midline

L5 spinous

process

L5-S1

disk

space

L4 lamina

lamina

L5 pedicle

L3-L4

facet joint

L4-L5 facet

L5-S1 facet

joint

L3-L4

joint

disk

space

L4-L5 disk

L4 pedicle

space

• The high-speed burr is used to remove the lamina.

L5 spinous

midline

process

lamina

L5-S1

disk

ligamentum

space

flavum

lamina

L5 pedicle

L3-L4

facet joint

L4-L5 facet

L5-S1 facet

joint

L3-L4

disk

space

L4 pedicle

• Detachment of the ligamentum flavum from the superior L4 lamina.

16 Minimally Invasive Laminectomy

contralateral

L5-S1 facet joint

L3 spinous

L4 spinous

superficial

process

L5 spinous

process

midline

process

dura

lamina

deep midline

lamina

L3-L4

facet joint

L4-L5 facet

L4 pedicle

L5-S1 facet

L5 pedicle

joint

• Undercutting the ipsalateral L4-L5 facet joint.

contralateral

L5-S1 facet joint

L5 pedicle

L3 spinous

process

L4 spinous

superficial

L5 spinous

process

midline

process

deep midline

dura

lamina

L3-L4

facet joint

L4 pedicle

L4-L5 facet

L5-S1 facet

joint

L5 pedicle

joint

• Palpation of the contralateral pedicle and lateral recess.

IV Lumbar Spine

contralateral

L5-S1 facet joint

contralateral

L5 root

L3 spinous

superficial

process

L5 spinous

midline

process

deep midline

dura

lamina

L3-L4

facet joint

L4 pedicle

L4-L5 facet

joint

L5-S1 facet

L5 pedicle

joint

L4-L5 disk

space

• The decompression occurs with the tube directed medially; therefore, the su-

perficial midline is crossed during the decompression.

• A completed laminectomy demonstrates that the thecal sac is completely de-

compressed, with the overlying paraspinal muscle preserved.

Potential Pitfalls

Operative times are typically longer, and increased complications may occur dur-

ing the initial minimally invasive surgical (MIS) experience. It is essential to master

open techniques before you attempt these less invasive options. When you transi-

tion from open to less invasive tubular techniques, it is critical to develop your skill

set in an algorithmic fashion. We suggest soft tissue decompression, followed by

stenosis, and finally, fusion techniques.

17 Minimally Invasive Far Lateral Diskectomy

Tips and Pearls Before You Begin

Far lateral disk herniations affect the nerve root exiting lateral to the neurofora-

men. Therefore, a standard hemilaminotomy will not allow for visualization of the

disk herniation without excessive or complete resection of the facet joint. L5-S1

disk herniations pose an additional anatomic challenge because the sacral ala and

iliac wing will often prevent a far lateral approach.

• Lateral fluoroscopic visualization is essential to confirm the appropriate level.

IV Lumbar Spine

L3-L4

facet

joint

L4-L5 facet

joint

L5-S1 facet

disk

joint

space

transverse

process

• The incision is typically made 4 cm lateral to the midline. The tube is docked onto

the lateral aspect of the pars interarticularis and the inferior transverse process.

L3-L4

facet

joint

L4-L5 facet

L5-S1 facet

joint

disk

space

transverse

process

intertransverse

septum

• The tube is docked lateral to the L4-L5 facet joint.

17 Minimally Invasive Far Lateral Diskectomy

L4-L5 disk

L4-L5 facet

herniation

joint

L5-S1

facet

joint

transverse

process

exiting L4

nerve root

• The intertransverse septum is exposed and is detached from the inferior trans-

verse process with a curved curette.

L4-L5 facet

joint

L5-S1

facet

joint

herniated

transverse

disk

process

ansverse

process

• The nerve root is typically displaced such that it is dorsal and lateral to the disk

herniation.

IV Lumbar Spine

L4-L5 facet

joint

L5-S1

facet joint

herniated

transverse

disk

process

space

ansverse

process

• The nerve root should be gently mobilized superiorly to expose the underlying

disk space.

L4-L5 facet

joint

disk

material

transverse

process

• A pituitary rongeur is used to remove the disk fragments.

17 Minimally Invasive Far Lateral Diskectomy

L4-L5

facet joint

L5-S1

facet joint

disk

space

ansverse

process

• A curette is placed into the site of the disk herniation.

L4-L5

facet joint

L5-S1

facet joint

disk

space

transverse

process

ansverse

process

• If there is any foraminal stenosis, a Kerrison rongeur can be passed into the

neuroforaminal space from the outside in, thereby resecting any foraminal or

extraforaminal osteophytes.

IV Lumbar Spine

Potential Pitfalls

Meticulous dissection is necessary to obtain hemostasis, particularly when the

intertransverse septum is resected. Bleeding, if not controlled, will result in poor

visualization of the disk herniation, with a resultant inadequate decompression.

18 Minimally Invasive Transforaminal Lumbar

Interbody Fusion

Tips and Pearls Before You Begin

Visualization of the disk space is essential. Complete resection of the facet joint

with removal of all overlying bone from the superior articular process of the in-

ferior vertebra should be performed. Disk space preparation is the key to an in-

creased likelihood of a successful arthrodesis. A combination of currettes and Ker-

rison rongeurs should be used to prepare the end plate. Fluorscopy may be used

to ensure that the anterior longitudinal ligament is not violated. Care should be

taken with paddle distractors and shavers, as these devices may compromise the

end plates, which can result in subsidence of the implant.

midline

L5 spinous

process

dura

L4 lamina

pars inter-

articularis

lamina

L5 pedicle

L4-L5 facet

L5-S1 facet

joint

L4-L5 disk

space

L4 pedicle

• With the working portal appropriately docked on the level of pathology, an

initial exposure can be performed.

• Often there are residual paraspinal muscle fibers that must be removed from

the lamina.

100

IV Lumbar Spine

midline

L5 spinous

process

dura

pars inter-

articularis

lamina

L5 pedicle

L4-L5 facet

joint

L5-S1 facet

joint

L4-L5 disk

exiting L4

space

L4 pedicle

nerve root

• Once the lamina is exposed, a high-speed burr is used to perform a laminec-

tomy. Bone is removed until only the flavum is visualized.

- The laminectomy is extended laterally through the pars interarticularis.

- Bone is saved in a bone trap.

18 Minimally Invasive Tranforaminal Lumbar Interbody Fusion

101

midline

L5 spinous

process

dura

lamina

L5 pedicle

L5-S1 facet

joint

L4-L5 disk

space

L4 pedicle

• The laminectomy is extended cranially until the end of the flavum insertion is

identified.

- Epidural fat or dura is often seen.

• This marks the cranial extent of the laminectomy.

• The burr is then directed directly laterally through the pars interarticularis.

102

IV Lumbar Spine

midline

L5 spinous

process

dura

lamina

L5 pedicle

L5-S1 facet

joint

L5 superior

L4-L5 disk

exiting L4

facet

space

nerve root

• Once the burr is through the pars, the inferior articular process can be removed,

completing the facetectomy and exposing the involved disk space.

midline

L5 spinous

process

dura

ligamentum

flavum

lamina

L5-S1 facet

joint

L5 superior

L4-L5 disk

exiting L4

facet

space

nerve root

L4 pedicle

• The ligamentum flavum can now be resected.

• Care is taken to preserve the flavum initially, as it protects the dura while the

decompression is being performed.

18 Minimally Invasive Tranforaminal Lumbar Interbody Fusion

103

midline

L5 spinous

process

dura

ligamentum

flavum

L4-L5 disk

space

lamina

L5 pedicle

L5-S1 facet

joint

L5 superior

exiting L4

facet

nerve root

• Bipolar cautery is used to coagulate the veins that overlie the disk space.

superficial

L5 spinous

midline

process

dura

deep

midline

lamina

L5 pedicle

L5-S1 facet

joint

L5 superior

cage in

L4-L5 disk

exiting L4

facet

space

nerve root

• Once the veins have been coagulated, the inferior pedicle (L5) and disk space

(L4-L5) can be visualized.

- The traversing nerve root (L5) is just medial to the pedicle.

- The exiting nerve root (L4) is above the disk space. It is not typically exposed.

104

IV Lumbar Spine

• The working space in the TLIF is lateral to the exiting root in the neuroforamen.

- Lateral fluoroscopic imaging is used when preparing the disk space.

18 Minimally Invasive Tranforaminal Lumbar Interbody Fusion

105

• The disk space is prepared using a combination of paddle distractors and end

plate shavers to remove the disk material.

106

IV Lumbar Spine

• Once the disk material has been removed and the end plates prepared, a bone

funnel is passed into the disk space.

- The bone collected during the laminectomy can then be placed into the disk

space.

• The interbody cage is then impacted into place.

- Care is taken to protect the nerve root during cage placement.

18 Minimally Invasive Tranforaminal Lumbar Interbody Fusion

107

dura

deep

midline

L5 traversing

nerve root

suction on TLIF

L4 exiting

working zone

nerve root

• The interbody cage has been placed into the prepared disk space.

- The cage is directed obliquely toward the midline.

- The tube can be directed medially to perform a contralateral decompression.

Potential Pitfalls

Inadequate resection of the facet joint will lead to decreased visualization of the

disk space. As a result, the transforaminal working zone will be narrowed and an

undersized implant will be placed, increasing the likelihood of cage migration and

pseudarthrosis.

19 Mini-Open Pedicle Screw Placement

midline

L5 spinous

process

dura

L4 lamina

pars inter-

articularis

lamina

L4-L5 facet

joint

L5-S1 facet

joint

pedicle

L4-L5 disk

L5 transverse

start

space

L4 pedicle

process

point

■ Step 1: Pedicle Start Point Is Identified

• The pedicle start point is identified through the working portal. This allows for

medial-lateral orientation in the anteroposterior (AP) plane.

108

19 Mini-Open Pedicle Screw Placement

109

• Lateral fluoroscopic imaging is used to confirm the direction in the cephalad-

caudal plane.

• A gear shift is placed through the pedicle start point to the desired depth under

direct lateral fluoroscopy.

110

IV Lumbar Spine

■ Step 2: Pedicle Is Cannulated

• The pedicle tract is probed.

19 Mini-Open Pedicle Screw Placement

111

• Pedicle screws are then placed.

• These same steps are repeated for the adjacent level.

112

IV Lumbar Spine

• A rod is then placed and secured through the tube.

L5 spinous

process

thecal sac

L4 lamina

L4 pedicle

L5 pedicle

L3-L4 facet

joint

L5-S1 facet

joint

rod

L4 pedicle

set screw

L5 pedicle

set screw

cage in L4-L5

exiting L4

disk space

nerve root

• Intraoperative view.

20 Percutaneous Pedicle Screw Placement

2 o’clock

pedicles

end plate

spinous

process

• The end plate is clearly visualized. The spinous process is centered between

both pedicles. The Jamshidi needle is started at the 2 o’clock position.

113

114

IV Lumbar Spine

pedicles

spinous

process

• The Jamshidi trocar is advanced 15 mm until it is centered in the pedicle.

20 Percutaneous Pedicle Screw Placement

115

medial

edge of

pedicle

• A guide wire is then advanced an additional 10 mm until it abuts the medial

wall of the pedicle on the AP image.

116

IV Lumbar Spine

medial

wall of

●

pedicle

guide wire

in adjacent

level

●

spinous

processes

end plate

●

• The steps are repeated for the adjacent level. End plate visualization and cen-

tering the spinous process are essential steps for ensuring accurate percutane-

ous screw placement.

20 Percutaneous Pedicle Screw Placement

117

●

pedicles

spinous

processes

●

• Guide wires have been placed into both pedicles on the AP view.

118

IV Lumbar Spine

posterior

vertebral

wall

• A lateral image is then obtained to confirm that the guide wires are past the

vertebral body wall. This image is extremely important, as it confirms that the

guide wire has not breached the medial wall of the pedicle before entrance into

the vertebral body. A cannula is then placed in between the guide wires.

20 Percutaneous Pedicle Screw Placement

119

pars inter-

articularis

disk

spaces

• The working dilator is docked over the pars interarticularis and disk space level.

• The disk space is prepared as previously described.

120

IV Lumbar Spine

inter-

vertebral

cage

• The pedicles are tapped over the guide wire.

20 Percutaneous Pedicle Screw Placement

121

cannulated

pedicle screw

(over guide wire)

inter-

vertebral

cage

cannulated

pedicle screw

(guide wire

removed)

• Cannulated pedicle screws are placed over the guide wire.

122

IV Lumbar Spine

cannulated

pedicle screws

rod

inter-

vertebral

cage

• The rod is passed submuscularly into the tulips of the pedicle screws after the

guide wires are removed. Gentle compression can be applied to the graft.

20 Percutaneous Pedicle Screw Placement

123

midline

(spinous

processes)

pedicle

rod

screws

intervertebral

cage

• Final AP image, demonstrating centered cage placement and gently converg-

ing pedicle screws.

21 Extreme (eXtreme) Lateral Interbody Fusion

Tips and Pearls Before You Begin

A good fluoroscopic image is extremely helpful. Adjust the cephalocaudal angle

of the C -arm to provide a clear lateral view of the end plates. There is a tendency

to cheat the initial exposure anteriorly to avoid the nerves posteriorly. However,

because the retractor is designed to prevent pressure on the posterior elements,

the aperture is preferentially expanded anteriorly. Therefore, the ideal initial tar-

get spot is the direct center of the lateral aspect of the disk, which will result in

retractor exposure of the anterior half of the disk space. Multilevel procedures

can be performed with the same skin incision but separate fascial incisions and

psoas muscle dilations. In degenerative scoliosis cases, coronal alignment can be

achieved from either side, but access is easier from the concave side, which allows

access to multiple levels through the same incision. The contralateral annulus

must be disrupted to achieve parallel distraction, optimal biomechanical position

of the implant, and optimal coronal alignment.

124

21 Extreme (eXtreme) Lateral Interbody Fusion

125

lateral femoral

cutaneous n. (L2-L3)

L3-

L4-

disk

psoas muscle

femoral n.

iliohypogastric n.

ilioinguinal n.

(L1)

• The patient is placed into a direct lateral position.

• It is essential that the patient be directly perpendicular to the ground to ensure

true anteroposterior (AP) and lateral fluoroscopic views of the disk space.

• AP and lateral fluoroscopic imaging is used to identify the disk space.

iliohypogastric n.

lateral femoral

cutaneous n.

L3-

disk

genitofemoral n.

ilioinguinal n.

lumbosacral

femoral n.

trunk

• A skin incision is made, exposing the fibers of the external oblique muscle.

126

IV Lumbar Spine

iliohypogastric n.

lat. femoral

cutaneous n.

L3-

disk

genitofemoral n.

psoas m.

genitofemoral n.

ilioinguinal n.

• The fibers of the internal oblique muscle lie underneath the external oblique.

- These fibers run in an opposite direction.

lat. femoral

cutaneous n.

genitofemoral n.

L4-

disk

ilioinguinal n.

lumbar

plexus

• Once the fibers of the internal oblique are split, the transversalis fascia is identified.

21 Extreme (eXtreme) Lateral Interbody Fusion

127

lat. femoral

cutaneous n.

L3-

disk

genitofemoral n.

lumbar plexus

lies within the

psoas muscle

psoas m.

iliohypogastric n.

• The transversalis fascia is bluntly opened, exposing the retroperitoneal fat.

vena cava

abdominal aorta

L4-L5

disk

nerve

plexus

• The psoas muscle is then identified. It can be either traversed with continuous

neuromonitoring or swept posteriorly.

• The lumbar plexus lies within the substance of the psoas, so care should be

taken to avoid the lumbar nerve roots, particularly at the L4-L5 level.

• Bipolar cautery is used to expose the disk space, removing any residual overly-

ing fibers of the psoas muscle.

128

IV Lumbar Spine

vena cava

nerve

plexus

• Once the disk space is exposed, an annulotomy can be performed.

- Note that the nerve root is posterior to the posterior retractor blade.

vena cava

abdominal aorta

• The end plate is carefully prepared, with particular attention to avoiding viola-

tion of the vertebral end plates.

• It is essential to prepare the entire end plate across to the contralateral side.

- Releasing the contralateral annulus will greatly improve exposure and allow

for correction of coronal plane deformities.

21 Extreme (eXtreme) Lateral Interbody Fusion

129

vena cava

abdominal aorta

• An intervertebral cage is gently impacted into place.

- The cage should span the entire width of the vertebral body, thereby resting

on the ring apophysis.

▫ This placement will minimize the likelihood of cage subsidence.

- The cage is placed using AP and lateral fluoroscopic imaging.

Potential Pitfalls

Failing to position the patient properly makes for a tedious procedure. A few ex-

tra minutes in the beginning will save a lot of time in the end. Disk removal and

end-plate preparation should be thorough to facilitate fusion and should extend

across the disk space through the contralateral annulus. Failure to release the

contralateral annulus may result in difficulty in implant positioning, leading to

coronal imbalance if the implant is inserted asymmetrically, or in subsidence if a

short implant is chosen. End-plate compromise should be avoided by using care-

ful preparation techniques that spare the end plate. If the height of the implant

is oversized, it may cause rupture of the anterior longitudinal ligament, displace-

ment of the implant anteriorly, or difficulty in distracting adjacent levels in multi-

level procedures.

22 Minimally Invasive Lumbar Corpectomy

Tips and Pearls Before You Begin

The approach for the minimally invasive lumbar corpectomy is similar to that of

the extreme lateral interbody fusion. However, care should be taken to be more

anterior to the psoas muscle, because two disk space levels are treated simulta-

neously, which increases the likelihood of postoperative lumbar nerve root dys-

function. The upper lumbar levels (L1-L3) are much easier to treat because the

psoas is less prominent at these levels and the retractor can be safely positioned

anterior to the psoas. At the L4 vertebral level, the patient should be informed

that there may be a chance for postoperative psoas and lower lumbar nerve root

dysfunction. In the majority of cases, the dysfunction resolves within 2-4 weeks

postoperatively.

genitofemoral n.

segmental

arteries

iliac vein

L4-L5

L3-

and artery

L3 L2-

disk

ascending

lumbar vein

iliohypogastric n.

• Typical lateral positioning of the patient.

130

22 Minimally Invasive Lumbar Corpectomy

131

ALL

L3-

L2-

disk

PLL

psoas muscle

ascending

lumbar vein

• The dilator has been docked over the pathologic vertebral body. The psoas is

retracted posteriorly.

ALL

L2-

disk

L3-

disk

PLL

ascending

lumbar vein

• A high speed burr is used to remove the L3 vertebral body.

132

IV Lumbar Spine

thin anterior

wall of L3

PLL

nerve

roots

ascending

lumbar vein

L2 spinous

process

• The corpectomy is complete. The L2-L3 and L3-L4 disk spaces have been re-

sected. The L3 vertebral body has been removed, leaving only a thin wall and

the PLL intact.

anterior rim

of L3

ascending

lumbar vein

L2 spinous

process

• An expandable titanium cage is appropriately sized and distracted until a press

fit is obtained.

22 Minimally Invasive Lumbar Corpectomy

133

anterior rim

of L3

PLL

ascending

lumbar vein

L2 spinous

process

• The cage is shown in its final distracted position. The bone graft has been

placed inside and around the cage.

Potential Pitfalls

Care should be taken to place the tube along the medial/posterior vertebral body

edge. Placement of the tube too far anteriorly will result in resection of the ante-

rior longitudinal ligament and an inadequate spinal canal decompression. In the

vast majority of cases, the pathology lies along the posterior vertebral body wall

and spinal canal, and an anterior retractor placement will result in inadequate

treatment. Care should also be taken to avoid disrupting the end plate, as cage

subsidence is much greater with corpectomy cages than in single-level disk space

implants.

23 Anterior Lumbar Interbody Fusion

Tips and Pearls Before You Begin

Lateral fluoroscopy is helpful during preoperative localiztion. Localization will help

to minimize tissue dissection and reduce surgical time. Lateral fluoroscopy is also

beneficial during implant placement. The ideal implant position is a few millime-

ters recessed deep to the anterior margin of the adjacent end plates. The osteo-

phytes should be rongeured off the anterior end plates before the diskectomy,

as they may obscure normal anatomy and result in improper placement of the

interbody implant. Once the anterior annulus is incised a Cobb elevator may be

used to detach the Sharpey fibers from the superior and inferior end plates, and

then the disk can be removed in one piece. Overly sclerotic end plates can be

burred to expose the bleeding end plates. Sequential dilation of the disk space

with sizers is an important step to distract the end plates adequately and insert a

press-fit implant.

aorta

ascending

vena

lumbar v.

L3-L4 disk

cava

genitofemoral

nerve

genitofemoral

ureter

nerve

epigastric

L4-L5 disk space

medial sacral

artery

artery and vein

hypogastric plexus

over L5

internal

iliac vessels

L5-S1 disk

sacrum

134

23 Anterior Lumbar Interbody Fusion

135

■ Exposure and Approach

• A lateral fluoroscopic image should be obtained before incision to localize the

surgical level. At the L5-S1 level, the great vessels (aorta/vena cava) have bi-

furcated. At the L4-L5 disk space level, the great vessels are retracted to the

right. At L4-L5, the ascending lumbar vein may need to be ligated to mobilize

the vessels. Once the incision has been made, the fascia of the musculus rectus

abdominis is incised. The fascial incision can made either horizontally (in line

with the skin incision) or vertically, depending upon the surgeon’s preference.

genitofemoral

aorta

epigastric

ureter

nerve

vena

artery

cava

L3-L4 disk

ascending

lumbar vein

rectus fascia

sacrum

• Rectus fascia identified.

136

IV Lumbar Spine

ureter

epigastric

L3-L4 disk space

artery

genitofemoral

nerve

rectus fascia

hypogastric

plexus over L5

L5-S1 disk space

• The muscle belly of the rectus is mobilized. Some surgeons argue that mobiliz-

ing the lateral edge of the rectus results in denervation of the muscle, while

others state that medial mobilization increases the likelihood for abdominal

hernias. Posterior to the rectus is the rectus sheath, which is incised carefully,

exposing the retroperitoneum.

23 Anterior Lumbar Interbody Fusion

137

median

sacral a.

ureter

genitofemoral

nerve

epigastric

L5-S1 disk

artery

iliopsoas

muscle

internal

iliac vessels

• The retroperitoneum is then swept to the left (the patient’s right). Retractors

are placed along the right side of the disk space to hold the retroperitoneum

out of the surgeon’s field of view. Care should be taken to identify the ureter

and to retract it along with the retroperitoneal contents. At L5-S1, the median

sacral artery may need to be ligated or cauterized prior to the disk space expo-

sure. Care should be taken to retract gently against the verterbal body and disk

space, thereby avoiding any undue pressure on the iliac veins.

138

IV Lumbar Spine

L5-S1 disk space

• Once the disk space is identified, an annulotomy can be made with either a

knife or an electrocautery device. This procedure is similar to the end plate

preparation performed during an anterior cervical diskectomy and fusion.

L5 inferior

end plate

trial sizer

S1 superior end plate

• Care is taken to preserve the integrity of the vertebral end plate. End plate

violation may result in implant subsidence and migration. Lateral fluoroscopy

should be used to recess the implant below the level of the anterior vertebral

body margin.