OKU 5 Orthopaedic Knowledge Update Spine

OKU
5
Orthopaedic
Knowledge
Update
Spine
EDITOR
Eeric Truumees, MD
Professor
Department of Surgery
University of Texas at Austin, Dell Medical School
CEO, Seton Brain and Spine Institute
Austin, Texas
COEDITOR
Heidi Prather, DO
Professor
Vice Chair, Department of Orthopaedic Surgery
Division Chief, Physical Medicine and Rehabilitation
Departments of Orthopaedic Surgery and Neurology
Washington University School of Medicine
St. Louis, Missouri
Developed by the North American Spine Society

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William J. Maloney, MD
President
David A. Halsey, MD
First Vice-President
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Second Vice-President
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Treasurer
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Past-President
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James J. Balaschak
Basil R. Besh, MD
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Lisa K. Cannada, MD
Brian J. Galinat, MD, MBA
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Chief Executive Officer (ex-officio)
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Published 2017 by the
American Academy of Orthopaedic Surgeons
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Rosemont, IL 60018
Copyright 2017
by the American Academy of Orthopaedic Surgeons
Library of Congress Control Number: 2017951329
eISBN 978-1-975118-41-9
Printed in the USA
Acknowledgments
Editorial Board
Orthopaedic Knowledge Update: Spine 5
Eeric Truumees, MD
Professor
University of Texas at Austin, Dell Medical School
CEO, Seton Brain and Spine Institute
Austin, Texas
Heidi Prather, DO
Professor
Vice Chair, Department of Orthopaedic Surgery
Division Chief, Physical Medicine and Rehabilitation
Departments of Orthopaedic Surgery and Neurology
St. Louis, Missouri
Christopher D. Chaput, MD
Chief of the Division of Spine Surgery
Department of Orthopedics
Baylor Scott and White Health, Central Texas
Temple, Texas
Charles H. Cho, MD, MBA

Interventional and Diagnostic Radiology
Department of Radiology
Brigham and Women’s Hospital
Harvard Medical School
Boston, Massachusetts
Mitchel B. Harris, MD
Professor of Orthopaedics
Department of Orthopaedic Surgery
Scott R. Laker, MD
Associate Professor
Department of Physical Medicine and Rehabilitation
University of Colorado Hospital
Aurora, Colorado
Ronald A. Lehman Jr, MD

Professor of Orthopaedic Surgery, Tenure
Chief, Degenerative, Minimally Invasive, and Robotic Spine Surgery
Director, Athletes Spine Center
Director, Spine Research
Co-Director, Adult and Pediatric Spine Fellowship
Advanced Pediatric and Adult Deformity Service
Columbia University Medical Center
New York, New York
Charles A. Reitman, MD
Professor and Vice Chairman
Department of Orthopaedics
Medical University of South Carolina
Charleston, South Carolina
Andrew J. Schoenfeld, MD
Assistant Professor
Jeffrey C. Wang, MD
Chief, Orthopaedic Spine Service
Co-Director, USC Spine Center
Professor of Orthopaedic Surgery and Neurosurgery
USC Spine Center
Los Angeles, California
North American Spine Society

Board of Directors, 2016-2017
F. Todd Wetzel, MD
President
Daniel K. Resnick, MD, MS

First Vice President
Jeffrey C. Wang, MD
Second Vice President
William J. Sullivan, MD
Secretary
Eeric Truumees, MD
Treasurer
Christopher M. Bono, MD
Past President
Edward Dohring, MD
Education Council Director
Alan S. Hilibrand, MD
Continuing Medical Education Chair
Donna Ohnmeiss, PhD

Education Publishing Chair
Zoher Ghogawala, MD, FACS

Research Council Director

Evidence Compilation & Analysis Chair
D. Scott Kreiner, MD
Clinical Research Development Chair
Administration & Development Council Director
Jerome Schofferman MD
Ethics and Professionalism Committee Chair
Joseph S. Cheng, MD
Section Development Chair
Mitchel B. Harris, MD, FACS

Governance Committee Chair
David R. O’Brien Jr, MD

Health Policy Council Director
Mitchell F. Reiter, MD, PC

Payer Policy Review Committee Chair
John G. Finkenberg, MD
Advocacy Council Director
Norman B. Chutkan, MD
At-Large Member
Matthew Smuck, MD
At-Large Member
David Rothman, PhD

Ethicist
Eric J. Muehlbauer, MJ, CAE
Executive Director
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Contributors
Oussama Abousamra, MD
Clinical Fellow
Johns Hopkins Hospital
Baltimore, Maryland
Uzondu F. Agochukwu, MD
Assistant Professor
Medical College of Georgia at Augusta University
Augusta, Georgia
Ilyas S. Aleem, MD, MSc, FRCSC

Assistant Professor
University of Michigan
Ann Arbor, Michigan
Paul A. Anderson, MD
Professor, Orthopedic Surgery
Department of Orthopedic Surgery and Rehabilitation
University of Wisconsin
Madison, Wisconsin
Amandeep Bhalla, MD
Assistant Professor
Harbor – UCLA Medical Center
David Geffen School of Medicine at UCLA
Torrance, California
Christopher M. Bono, MD
Chief, Orthopaedic Spine Service
Étienne Bourassa-Moreau, MD, MSc

Fellow in Spine Surgery
Department of Orthopedic Surgery
University of British Columbia
Vancouver, British Columbia, Canada
Daniel Bouton, MD
Fellow
Texas Scottish Rite Hospital for Children
Dallas, Texas
Joseph S. Butler, PhD, FRCS

Clinical Fellow
Rothman Institute
Thomas Jefferson University Hospitals
Philadelphia, Pennsylvania

Radiologist
Brigham and Women’s Hospital, Harvard Medical School
Norman B. Chutkan, MD, FACS

Executive Director
The Orthopedic and Spine Institute
Banner University Medical Center Phoenix
Phoenix, Arizona
Berdale Colorado, DO, MPH

Assistant Professor
St. Louis, Missouri
John G. DeVine, MD
Professor
Medical College of Georgia at Augusta University
Augusta, Georgia
Marco Ferrone, MD, FRCSC

Orthopaedic Spine & Oncology
Jeffrey S. Fischgrund, MD
Chairman
William Beaumont Hospital
Royal Oak, Michigan
Kenneth Foxx, MD
Spine Surgery Fellow
University of Rochester Medical Center
Rochester, New York
Jason Friedrich, MD
Assistant Professor, Associate Fellowship Director
Department of Physical Medicine & Rehabilitation
University of Colorado School of Medicine
Aurora, Colorado
Christopher G. Furey, MD
Chief, Spine Section
Henry Bohlman, MD Endowed Chair
University Hospitals Cleveland Medical Center
Cleveland, Ohio
Michelle Gittler, MD
Medical Director, Chairperson
Department of Physical Medicine and Rehabilitation
Schwab Rehabilitation Hospital
Chicago, Illinois
John Glaser, MD
Professor
Medical University of South Carolina
Charleston, South Carolina
S. Raymond Golish, MD, PhD, MBA

Medical Director of Spinal Surgery
Jupiter Medical Center
Palm Beach, Florida
Richard D. Guyer, MD
Texas Back Institute Fellowship Director
Associate Clinical Professor
University of Texas Southwestern School of Medicine
Dallas, Texas
Raymond J. Hah, MD
Assistant Professor
Keck School of Medicine
University of Southern California
Los Angeles, California
Clifton W. Hancock, MD, MS, MBA

Texas Back Institute Fellow
Texas Back Institute
Plano, Texas
Colin B. Harris, MD
Assistant Professor
Rutgers University – New Jersey Medical School
Newark, New Jersey
Alan S. Hilibrand, MD
The Joseph and Marie Field Professor of Spinal Surgery
Rothman Institute
Jefferson Medical College
John A. Hipp, PhD

Chief Scientist
Medical Metrics, Inc.
Houston, Texas
Samantha R. Horn, BA
Research Fellow
NYU Hospital for Joint Diseases
NYU Langone Medical Center
New York, New York
Serena S. Hu, MD
Professor and Vice Chairman
Chief, Spine Surgery Service
Professor of Neurological Surgery (by courtesy)
Stanford University School of Medicine
Stanford, California
Keith L. Jackson II, MD

Chief, Spine Surgery
Department of Orthopaedics and Rehabilitation
Womack Army Medical Center
Fort Bragg, North Carolina
M. Burhan Janjua, MD
Neurospine Fellow
New York, New York
Darnell T. Josiah, MD, MS

Clinical Instructor
Department of Neurosurgery
University of Wisconsin – Madison
Madison, Wisconsin
Brian J. Kelley, MD, PhD

Advanced Pediatric Spinal Deformity Fellow
Department of Pediatric Orthopedic Surgery
Morgan Stanley Children’s Hospital
New York, New York
Harish Kempegowda, MD
Spine Fellow
MedStar Union Memorial Hospital
Baltimore, Maryland
Jad G. Khalil, MD
Assistant Professor
Oakland University
William Beaumont Hospital
Royal Oak, Michigan
D. Scott Kreiner, MD
Partner
Ahwatukee Sports & Spine
Phoenix, Arizona
Mark F. Kurd, MD
Assistant Professor, Orthopaedic Surgery
The Rothman Institute
Thomas Jefferson University Hospitals
Robert M. Kurtz, MD
Fellow
Brigham and Women’s Hospital, Harvard Medical School
Brian K. Kwon, MD, PhD, FRCSC

Professor and Canada Research Chair in SCI
University of British Columbia
Vancouver, British Columbia, Canada
Hubert Labelle, MD
Professor of Surgery
University of Montreal
Montreal, Quebec, Canada
Adam LaBore, MD
Associate Professor
Physical Medicine and Rehabilitation
St. Louis, Missouri
John M. Lavelle, DO
Spine Physician
Tennessee Orthopaedic Clinics
Knoxville, Tennessee
Ronald A. Lehman, Jr, MD

Professor of Orthopaedic Surgery, Tenure
Chief, Degenerative, Minimally Invasive, and Robotic Spine Surgery
Director, Athletes Spine Center
Director, Spine Research
Co-Director, Adult and Pediatric Spine Fellowship
Advanced Pediatric and Adult Deformity Service
The Spine Hospital - Columbia University Medical Center
New York, New York
Lawrence G. Lenke, MD
Professor of Orthopedic Surgery with Tenure
New York, New York
Thomas J. Lotus, DC, FACO, Cert. MDT

President/Owner
Spine & Sports Center of Chicago
Chicago, Illinois
Jean-Marc Mac-Thiong, MD, PhD

Associate Professor
Université de Montréal
Montréal, Québec, Canada
Benjamin Marshall, DO
Fellow Physician
Department of Physical Medicine & Rehabilitation
University of Colorado School of Medicine
Aurora, Colorado
John P. Metzler, MD
Associate Professor
Division of Physical Medicine and Rehabilitation
Washington University
St. Louis, Missouri
Patrick B. Morrissey, MD
Orthopaedic Spine Fellow
Rothman Institute
Isaac L. Moss, MDCM, MASc, FRCSC

Assistant Professor
University of Connecticut Health Center
Farmington, Connecticut
Ahmad Nassr, MD
Consultant
Associate Professor
Mayo Clinic
Rochester, Minnesota
Annie O’Connor, MSPT, OCS, Cert. MDT

Clinical Manager
River Forest Spine & Sport Center
Rehabilitation Institute of Chicago
Chicago, Illinois
Donna D. Ohnmeiss, DrMed

Texas Back Institute Research Foundation
Plano, Texas
Stefan Parent, MD, PhD

Associate Professor
Head, Paediatric Orthopaedic Surgery Service
Academic Chair in Pediatric Spinal Deformities of CHU Ste-Justine
Department of Surgery, CHU Ste-Justine
Université de Montréal
Montréal, Québec, Canada
Peter G. Passias, MD
Assistant Professor
New York, New York
Rakesh D. Patel, MD
Assistant Professor, Spine Service
University of Michigan Health System
Ann Arbor, Michigan
Gregory W. Poorman, BA
Research Fellow
New York, New York
Michael L. Reed, DPT, OCS

President and CEO
Spine Trust
Palm Beach Gardens, Florida
Daniel K. Resnick, MD, MS

Professor
Department of Neurological Surgery
University of Wisconsin
Madison, Wisconsin
Richard V. Roberts, MD
Spine Research Fellow
Beaumont Hospital
Royal Oak, Michigan
James O. Sanders, MD
Professor of Orthopaedics and Pediatrics
Department of Orthopaedics and Rehabilitation
University of Rochester
Rochester, New York
Timothy Sanford, MD
Physician
Physical Medicine and Rehabilitation
Ahwatukee Sports & Spine
Phoenix, Arizona
Zeeshan M. Sardar, MD, MSc

Assistant Professor
Temple University
Jerome Schofferman, MD
Founder and Member, Section on Rehabilitation, Interventional and Medical
Spine
Chair, Committee on Ethics and Professionalism
North American Spine Society
Sausalito, California
Joseph H. Schwab, MD, MS

Assistant Professor
Massachusetts General Hospital, Harvard Medical School
Paul Sponseller, MD, MBA

Professor and Head, Division of Pediatric Orthopaedics
Johns Hopkins Hospital
Baltimore, Maryland
Daniel J. Sucato, MD, MS

Chief of Staff
Texas Scottish Rite Hospital
University of Texas at Southwestern Medical Center
Dallas, Texas
Chi-Tsai Tang, MD
Assistant Professor
Division of Physical Medicine and Rehabilitation
St. Louis, Missouri
P. Justin Tortolani, MD
Chief, Division of Spine Surgery
Director, Spinal Reconstructive Fellowship
MedStar Union Memorial Hospital
Baltimore, Maryland
Michael G. Vitale, MD, MPH

Ana Lucia Professor of Pediatric Orthopaedic Surgery
Director, Division of Pediatric Orthopaedics
Chief, Pediatric Spine and Scoliosis Service
Morgan Stanley Children’s Hospital of New York - Presbyterian
New York, New York
Michael J. Vives, MD
Associate Professor
Rutgers University – New Jersey Medical School
Newark, New Jersey
Gregory Whitcomb, DC
Assistant Professor
Department of Neurosurgery
Medical College of Wisconsin
Milwaukee, Wisconsin
Kirkham B. Wood, MD
Professor
Stanford University
Palo Alto, California
Samuel A. Yoakum, DO
Non-Operative Spine Specialist
Tennessee Orthopaedic Clinics
Knoxville, Tennessee
Haitao Zhou, MD
Acting Instructor
Orthopaedics and Sports Medicine
University of Washington
Harborview Medical Center
Seattle, Washington
Craig Ziegler, MD
Sports Medicine Fellow
Washington University Orthopedics
Washington University
St. Louis, Missouri
Preface
This fifth edition of Orthopaedic Knowledge Update Spine (OKU Spine 5)
seeks to maintain the tradition of excellence fostered by previous editors and
authors and recognize the rapidly changing world of spine care. Not only
have the sources of data greatly increased in the 5 years since the publication
of the prior edition of this work, but so have the means of accessing this
information. Excellent research has emerged from throughout the world,
including rapidly growing input from Asia. This research is often published
in a host of new journals, and much of it is directly available on the Internet.
For both learners and specialists working to maintain up-to-date knowledge,

the challenge is not finding information, but rather sifting through the
mountains of available data. The editors of OKU Spine 5 sought to address
that challenge by assembling more than 80 experts from diverse backgrounds
and regions and representing various disciplines and subspecialty interests.
Together, we seek to provide concise answers to the questions “where are we
in spine care?” and “where are we going”? Toward this end, the powerful
OKU format allowed us to organize this information. Most topics begin with
a review of critical background information, followed by an update of the
literature from the past 5 years. Each chapter offers an annotated bibliography
to guide the readers’ further exploration of a topic.
Our thanks go to the project manager, Kim Hooker, and editorial team at the
American Academy of Orthopaedic Surgeons (AAOS), including Lisa
Claxton Moore, Kathleen Anderson, Laura Goetz, Steven Kellert, Genevieve
Charet, and Rachel Winokur. To ensure timeliness, this book had very tight
deadlines. The AAOS staff was instrumental in moving the project forward.
They also hosted many conference calls during which the editors and section
editors discussed concepts around section organization and author selection.
These initial discussions led to a particularly engaged author group and
strong content offering broad coverage of spine care with minimal
redundancy.
Today, optimal spine care requires an interdisciplinary approach with
invaluable input from our colleagues in physical medicine, rehabilitation,
anesthesiology, radiology, neurology, neurosurgery, rheumatology, and
internal medicine. That spectrum of caregivers is reflected in our selection of
contributors to this work. As with previous editions of OKU Spine, this
balance began with two book editors with different practices and training
backgrounds and continued with a diverse group of section editors. We are
indebted to the section editors—Chris Chaput, Charlie Cho, Mitchel Harris,
Scott Laker, Ronald Lehman Jr, Charlie Reitman, Andrew Schoenfeld, and
Jeffrey Wang—each a recognized expert in the field, for helping select topics
and authors and for shepherding those chapters through to completion.
Although each chapter stands on its own, the book also is organized with a
logic that allows it to be read cover to cover or section by section. OKU Spine
5 begins with an overview of spine anatomy and physiology. This section is
followed by a review of the assessment tools most useful to spine care
providers. Approaches to management are grouped by type and disease state
and include sections on medical and surgical management of spine disorders,
spine deformity, spine trauma, neoplastic and inflammatory conditions, and
the special populations affected by spine disorders.
For the first time, an OKU Spine update will be accompanied by section
commentaries written by international spine experts; these commentaries will
be available with the digital version of this work. The editors are indebted to
these contributors for providing an international perspective that further
emphasizes the wide-ranging approaches and viewpoints in current spine
care.
We thank the North American Spine Society (NASS) and the AAOS for the
honor of editing this book. We acknowledge our practices and our partners
who have been very patient with our volunteer efforts and the time required
for their completion. Finally, we thank our families for their patience while
we attended those evening conference calls and weekends spent tapping away
at the keyboard. With this done, we expect an increase in our exposure to
those loved ones, the sun, and improvement in our vitamin D levels.
Eeric Truumees, MD
Editor
Heidi Prather, DO
Coeditor
Table of Contents
Preface
Section 1: Spine Anatomy and Biomechanics
Section Editor:
Chapter 1
Musculoskeletal Anatomy and Physiology
Chapter 2
Spine Neuroanatomy and Physiology
Joseph S. Butler, PhD, FRCS Mark F. Kurd, MD
Chapter 3
Surgical Approaches to the Spine
Harish Kempegowda, MD P. Justin Tortolani, MD
Chapter 4
Spine Mechanics and Pathomechanics
John A. Hipp, PhD
Section 2: Diagnostics in Spine Care

Section Editor:
Chapter 5
Physical Examination in Spine Care
John P. Metzler, MD
Chapter 6
Spine Imaging
Charles H. Cho, MD, MBA Robert M. Kurtz, MD
Chapter 7
Electrodiagnostic Testing and Intraoperative Neurophysiologic
Monitoring
Berdale Colorado, DO, MPH James O. Sanders, MD Kenneth Foxx, MD
Chapter 8
Diagnostic Procedures in Spine Care
D. Scott Kreiner, MD Timothy Sanford, MD
Section 3: Medical Management of Spine Disorders
Section Editor:
Scott R. Laker, MD
Chapter 9
Transdisciplinary Care for Cervical Spine Disorders
Gregory Whitcomb, DC
Chapter 10
Interdisciplinary Care for Lumbar Spine Disorders
Michael L. Reed, DPT, OCS S. Raymond Golish, MD, PhD, MBA Jerome Schofferman,
MD
Chapter 11
Therapeutic Exercise
Annie O’Connor MSPT, OCS, Cert. MDT Thomas J. Lotus, DC, FACO, Cert. MDT
Chapter 12
Manual Medicine and Spine Care
Samuel A. Yoakum, DO John M. Lavelle, DO
Chapter 13
Alternative Medicine and Spine Care
Chi-Tsai Tang, MD Craig Ziegler, MD
Chapter 14
Nonsurgical Care of the Spine: Procedures
Jason Friedrich, MD Benjamin Marshall, DO
Section 4: Surgical Management of Degenerative Spine
Disorders
Section Editor:
Chapter 15
Cervical Degenerative Disease
Patrick B. Morrissey, MD Alan S. Hilibrand, MD
Chapter 16
Degenerative Disease of the Thoracic Spine
Christopher G. Furey, MD
Chapter 17
Lumbar Disk Herniations
Ilyas S. Aleem, MD, MSc, FRCSC Rakesh D. Patel, MD Ahmad Nassr, MD
Chapter 18
Lumbar Stenosis and Degenerative Spondylolisthesis
Jad G. Khalil, MD Jeffrey S. Fischgrund, MD Richard V. Roberts, MD
Chapter 19
Axial Pain and Lumbar Degenerative Disk Disease
Richard D. Guyer, MD Clifton W. Hancock, MD, MS, MBA
Chapter 20
Sacroiliac Joint Dysfunction
John Glaser, MD
Section 5: Spine Deformity

Section Editor:
Ronald A. Lehman Jr, MD
Chapter 21
Early-Onset Scoliosis and Congenital Spine Anomalies
Brian J. Kelley, MD, PhD
Michael G. Vitale, MD, MPH
Chapter 22
Juvenile and Adolescent Idiopathic Scoliosis
Daniel Bouton, MD
Daniel J. Sucato, MD, MS
Chapter 23
Neuromuscular Spine Deformity
Paul Sponseller, MD, MBA
Oussama Abousamra, MD
Chapter 24
Adult Spine Deformity
Zeeshan M. Sardar, MD, MSc Ronald A. Lehman Jr, MD Lawrence G. Lenke, MD
Chapter 25
Sagittal Imbalance of the Spine
Serena S. Hu, MD Kirkham B. Wood, MD
Chapter 26
Spondylolisthesis in Children and Young Adults
Stefan Parent, MD, PhD Hubert Labelle, MD Jean-Marc Mac-Thiong, MD, PhD
Section 6: Trauma
Section Editor:
Jeffrey C. Wang, MD
Chapter 27
Initial Management of the Patient With Spine Trauma
Brian K. Kwon, MD, PhD, FRCSC Étienne Bourassa-Moreau, MD, MSc
Chapter 28
Occipitocervical and Subaxial Cervical Trauma
Paul A. Anderson, MD Raymond J. Hah, MD
Chapter 29
Thoracolumbar and Lumbosacral Trauma
John G. DeVine, MD Uzondu F. Agochukwu, MD Keith L. Jackson II, MD
Chapter 30
Whiplash and Whiplash-Associated Disorders
Jerome Schofferman, MD
Chapter 31
Principles of Spinal Cord Injury Rehabilitation
Michelle Gittler, MD
Section 7: Neoplastic and Inflammatory Conditions
Section Editor:
Mitchel B. Harris, MD
Chapter 32
Metastatic Disease to the Spine
Marco Ferrone, MD, FRCSC
Chapter 33
Primary Tumors of the Spine
Joseph H. Schwab, MD, MS
Chapter 34
Intradural Spine Lesions
Daniel K. Resnick, MD, MS Darnell T. Josiah, MD, MS
Chapter 35
Spine Infections
Norman B. Chutkan, MD, FACS Haitao Zhou, MD
Chapter 36
Inflammatory Arthritides
Peter G. Passias, MD Gregory W. Poorman, BA M. Burhan Janjua, MD Samantha R. Horn,
BA
Section 8: Special Populations in Spine Care

Section Editor:
Andrew J. Schoenfeld, MD
Chapter 37
Clinical Outcome Measures for Spine
Donna D. Ohnmeiss, DrMed
Chapter 38
Spine Injuries in Sports
Michael J. Vives, MD Colin B. Harris, MD
Chapter 39
Osteoporosis
Amandeep Bhalla, MD Christopher M. Bono, MD
Chapter 40
Injured Workers and Disability Assessment
Adam LaBore, MD
Index
Section 1
Spine Anatomy and

Biomechanics
SECTION EDITOR:
Chapter 1
Musculoskeletal Anatomy and

Physiology
Abstract
The vertebral column is a complex three-dimensional structure whose
function in health and disease is determined by the anatomy and physiology
of the spine at its supporting structures, including the vertebrae, the disks,
and the intimate connections with the surrounding soft tissues. To
understand, diagnose, and safely treat patients with spinal pathology, it is
helpful for surgeons to review the basic anatomy of the spine and be aware
of recent developments in understanding how the anatomy of the vertebrae
and the surrounding tissues affect function.
Keywords: anatomy; applied anatomy; vertebrae
Dr. Moss or an immediate family member is a member of a speakers’ bureau or

has made paid presentations on behalf of Pfizer; serves as a paid consultant to
Atlas Spine, Avitus Orthopedics, Nuvasive, Spineart, and Stryker; has stock or
stock options held in Orthozon LLC; and serves as a board member, owner,
officer, or committee member of the North American Spine Society.
Introduction
A detailed knowledge of spine anatomy is a prerequisite for safe and effective
nonsurgical and surgical treatment of patients with spine pathology. The
vertebrae, intervertebral disks, and surrounding ligaments and muscles are
important determinants of spinal function, both in health and disease. The
evolving body of knowledge on spine anatomy, function, and the complex
interactions between the various elements that make up the spine allows a
deeper understanding of the pathogenesis of disease and the potential
development of future novel treatments.
Basic Anatomy
The spinal column consists of 24 vertebral segments. Except for the first
cervical level, all individual vertebrae share similar basic morphologic
characteristics, including a vertebral body, pedicles, a lamina, and a variety of
bony projections that serve as attachments for ligaments and muscles. The
mobile spine is traditionally divided into three regions consisting of 7
cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae. The sacrum
consists of five fused vertebrae, with no motion between the vertebrae.
Despite important similarities, substantial anatomic variation exists between
the vertebrae of each region, with the vertebrae being adapted to the varying
functional demands throughout the spine. A thorough understanding of these
variations is essential for the safe and effective management of spinal
pathology.
The functional spinal unit consists of two adjacent vertebrae and their
intervening intervertebral disk and facet joints. The facet joints are true
synovial joints with characteristics similar to those of other synovial
articulations in the body. The intervertebral disk, however, is the major load-
bearing structure of the spine and has unique characteristics. Each
intervertebral disk is composed of an inner gelatinous nucleus pulposus
consisting primarily of type II collagen and proteoglycans and surrounded by
a highly organized collagenous anulus fibrosus, which primarily consists of
type I collagen in concentric lamellae, with fibers lying in alternating
directions (Figure 1). These components are confined cranially and caudally
by the vertebral end plates, resulting in a confined hydraulic system with
biphasic viscoelastic biomechanical properties capable of withstanding
considerable compressive loads.
Ligaments
The spine is stabilized by several ligamentous structures. The anterior
longitudinal ligament (ALL) is found on the ventral aspect of the vertebral
body, extending from the skull to the sacrum. The ALL has several layers,
with its deepest and strongest attachments being to the articular lip at the
margins of each vertebra and its more superficial layers spanning multiple
vertebrae. The posterior longitudinal ligament (PLL) also spans from the
skull to the sacrum, but runs within the spinal canal on the dorsal aspect of
the vertebral body. Unlike the ALL, the PLL has attachments only at the disk
level, and it is bowstrung across the concavity of the vertebral bodies. The
PLL can be elevated by pathologic processes, including disk herniations,
hematomas, infections, and tumors. The location of the PLL reinforces the
central anulus fibrosus, with most posterior disk herniations occurring at the
lateral margin of the PLL. Because the ALL and PLL are innervated by the
sinuvertebral nerves, which are branches from the spinal nerves near the
origin of the anterior and posterior rami, they may be contributors to back
pain.
Figure 1 Hematoxylin and eosin-stained histologic section of an

intervertebral disk at low (A) and high (B) power. The
nucleus pulposus (*) is populated by clusters of cells within a
gelatinous matrix. A clear border (arrow) between the nucleus
pulposus and the anulus fibrosus is evident. The anulus fibrosus
demonstrates organized fibrocartilage lamellae (arrow head).
(Reproduced from Moss IL, An HS: Form and function of the
intervertebral disc, in O’Keefe R, Jacobs JJ, Chu CR, Einhorn TA:
AAOS Orthopaedic Basic Science, ed 4. Rosemont, IL, American
Academy of Orthopaedic Surgeons, 2013, pp 253-260.)
The ligamentum flavum is an important anatomic structure to consider

during surgical decompression because it is a major contributor to spinal
canal stenosis. In contrast with the ALL and PLL, the ligamentum flavum is a
noncontiguous structure, with attachments to the ventral surface of the cranial
lamina and superior surface of the caudal lamina of each individual
functional spinal unit. When entering the canal with a Kerrison rongeur or
burr, surgeons often exploit the fact that the ligamentum flavum extends
halfway to two-thirds up the ventral surface of the cephalad lamina because
this natural anatomic barrier can help prevent inadvertent durotomy.1
Development
The spinal column is formed from the paraxial mesoderm in a process called
somatogenesis.2 As the body axis elongates, individual somites are added on
either ventral portion of the somite, which becomes the mesenchymal
sclerotome and is responsible for the formation of the vertebrae and the
anulus fibrosus. The nucleus pulposus is formed from the remnant of the
notochord and is populated by cells of notochordal origin in early life. These
cells are subsequently replaced by chondrocyte-like cells by the end of the
first decade of life. Each vertebra is formed by three primary ossification
centers—the centrum, neural arch, and a costal element. Failure of one or
more of these ossification centers to develop can result in the formation of a
hemivertebra, which often causes substantial deformity (referred to as
congenital deformity).3 Failure of the somite to fully segment results in the
formation of block vertebrae or unsegmented bars. The combination of a
hemivertebra and a contralateral unsegmented bar leads to the most
progressive form of congenital scoliosis.
Muscles
The paraspinal musculature plays an important role in stabilizing the spine
and maintaining upright posture. In the cervical spine, the paraspinal muscles
are divided into deep and superficial groups, with the deep musculature
mainly responsible for spinal stability and the superficial musculature mainly
responsible for movement (Figure 2). An increased cross-sectional area in
the deep cervical extensor muscles is associated with a higher rate of bony
union after anterior cervical fusion.4 In the thoracolumbar spine, the
paraspinal musculature is generally divided into the deep multifidus muscles
and the more superficial erector spinae muscles. The multifidus is considered
the major posterior stabilizing muscle of the spine. Its large cross-sectional
area and sarcomere orientation allow it to generate large forces with small
changes in length.5 The multifidus muscle originates from the spinous
process of a single level and typically inserts three levels caudal (on the
mammillary process in the lumbar spine). At each level, the multifidus is
innervated by the medial branch nerve of the posterior ramus of the spinal
nerve, which exits the spinal canal superolateral to the facet joint. Multifidus
atrophy is seen after traditional open approaches to the spine and results from
a combination of denervation, thermal injury, and pressure necrosis caused
by prolonged retraction.5 Medial branch nerve ablations, which are often
performed to treat back pain, may lead to multifidus atrophy as well.6
Figure 2 Axial T2-weighted magnetic resonance images of normal

midcervical spine muscular. A, The anterior flexor longus
collis (green), the deep extensors semispinalis cervicis and multifidus
muscle (yellow), and the superficial extensors semispinalis capitus,
splenius capitus, and longissimus muscles (red). B, Normal lumbar
spine musculature at the L4-L5 disk space demonstrating the psoas
muscle (green), the deep extensor multifidus muscle (yellow), and
superficial erector spinae muscle (red). C, Lumbar spine musculature
after open decompression shows substantial fatty atrophy of the
multifidus muscle (yellow).
Recently, the health and function of the paraspinal musculature has been
investigated as it relates to back pain and surgical success.7-9Paraspinal
muscle atrophy and fatty infiltration, most prominently affecting the
multifidus, has been associated with chronic low back pain; however, it is
unclear if this change is causative or related to disuse in patients with long-
term pain.7 Paraspinal atrophy and fatty infiltration also have been associated
with an increased risk of adjacent-segment degeneration after lumbar fusion.8
Many minimally invasive approaches to the lumbar spine have been designed
to preserve the medial branch nerve and minimize trauma to the multifidus.9
Spinal Balance
Positioning of the C7 vertebrae over the sacrum is essential for the
maintenance of upright posture and efficient locomotion. Proper positioning
is achieved by balancing the curvatures of the various anatomic regions of the
spine, including lordosis of approximately 60° in the lumbar region and
approximately 20° in the cervical region, and kyphosis of approximately 40°
in the thoracic and sacral regions10 (Figure 3).
The sagittal vertical axis is measured as the distance between the
posterior corner of the S1 superior end plate and a vertical plumb line from
the midpoint the C7 vertebral body. Increase in the sagittal vertical axis is
linearly correlated with more pronounced symptoms and disability.11 Lumbar
lordosis is not evenly distributed, with two-thirds of overall lumbar lordosis
contributed by L4-S1. Optimal lumbar lordosis is closely related to an
individual’s pelvic incidence, which is an important parameter to consider
when planning corrective surgery for spine deformity. Recent evidence has
shown that an individual’s cervical lordosis is related to his or her cranial
incidence, an anatomic parameter specific to an individual’s skull12 (Figure
4). Variation occurs in both sagittal balance and pelvic parameters as a result
of shifting from a standing to a sitting position, with a reduction in both
lumbar lordosis and thoracic kyphosis and a forward shift in the sagittal
vertical axis.13 The relevance of this information when planning spine
deformity correction has yet to be determined. With aging, the regional
curvatures often change, often with an increase in thoracic kyphosis.
However, asymptomatic individuals may maintain a stable global balance by
compensation in other areas of the spine.14
Applied Anatomy by Region
Cervical Spine
Occipitocervical Stability
The occipitocervical complex, which extends from the occiput to the C2-3
disk space, consists of specialized bony and ligamentous structures to
stabilize this area of vital anatomy while also acting as the major contributor
to cervical range of motion. The tectorial membrane, once thought to be the
primary stabilizer of the occipitoatlantal articulation, is an extension of the
PLL and runs from the anterolateral edge of the foramen magnum to the
posterior surface of the C2 body and odontoid process. A recent study
performed using modern biomechanical techniques demonstrated that the
primary stabilizers of the craniocervical junction are the transverse and alar
ligaments.15
Figure 3 Illustration shows normal global sagittal balance measured

by the sagittal vertical axis (SVA), a line drawn vertically
from the center of the C7 vertebral body. Normal balance results from
a balanced combination of cervical lordosis (CL), thoracic kyphosis
(TK), and lumbar lordosis (LL).
The cruciate ligament, the key structure in atlantoaxial stability, consists
of vertical and transverse components, which stabilize the odontoid to the
occiput and atlas, respectively (Figure 5). Disruption of the occipitocervical
complex, which can result from high-energy trauma, can lead to
occipitoatlantal or atlantoaxial dissociation. The sensitivity of plain
radiography to detect these often-fatal injuries has been questioned. Efforts
have been undertaken to define parameters predictive of ligamentous injury
based on CT and MRI, which are commonly obtained imaging studies in
trauma settings. On CT, a basion-dens interval of greater than 10 mm and a
C1-C2 lateral mass interval of 4 mm or greater are highly sensitive
measurements for the detection of occipitocervical complex instability.16
MRI studies have defined two patterns of occipitocervical complex injury
based on the integrity of the occipitoatlantal capsular ligaments.17
Atlantoaxial dissociation occurs when occipitoatlantal capsular ligaments are
preserved but the cruciate ligament is disrupted. In patients with combined
occipitoatlantal and atlantoaxial dissociation, both the occipitoatlantal
capsular ligaments and the cruciate ligaments are disrupted.17 It may be
easier to recognize a true dissociation by evaluating not only the midline
structures (eg, basion-dens interval), but also the congruency and the
displacement of the occiput-C1 articular surfaces.
Figure 4 EOS (EOS Imaging) image of the head and cervical spine
demonstrating the cervical incidence as the angle between
a line drawn perpendicular to the center of the McGregor line and a
line from the sella turcica (approximate center of rotation of the skull)
to the center of the McGregor line. (Reproduced with permission from
Le Huec JC Demezon H, Aunoble S: Sagittal parameters of global
cervical balance using EOS imaging: Normative values from a
prospective cohort of asymptomatic volunteers. Eur Spine J
2015;24[1]:63-71.)
Vertebral Artery
The foramen transversarium is a key distinguishing anatomic feature of the
cervical vertebrae from C2-C7. The vertebral artery, which is a branch of the
subclavian artery, usually enters the foramen of C6, runs cranially to exit at
C2, and then proceeds around the lateral mass of C1 to the superior surface of
the posterior C1 arch and enters the foramen magnum (Figure 6). Frequent
variations exist in the size and position of the foramen transversarium and the
artery contained within.18 In rare instances, the artery can run through the
lateral aspect of the vertebral body and entirely outside the foramen. Thus, a
careful review of axial imaging studies is essential when planning cervical
instrumentation. The vertebral artery can be injured when using a burr to
remove the uncovertebral joint. Fibrous bands, which connect the nerve root
to the vertebral artery, can tear this vessel even when the burr remains
medial. The vertebral artery is most at risk for injury during the posterior
instrumentation of C1 and C2. In addition, a fine-cut CT scan or CT
angiogram is helpful when planning instrumentation at C1 and C2. The C2
pedicle has substantial anatomic variation in up to 18% of individuals, which
can put the vertebral artery at risk for injury.19 The Harms technique for C1-
C2 fixation (with C1 lateral mass and C2 pedicle screws) has gained
popularity over the Magerl transarticular screw technique because it provides
greater freedom for screw trajectory and potentially reduces the risk of
vertebral artery injury.20
Figure 5 A, Illustration demonstrating the sagittal view of the
occipitocervical articulation. Posterior (B) and anterior (C)
illustrations of the atlantoaxial articulation. AC = accessory ligament,
AL = alar ligament, AP = apical ligament, TR = transverse atlantal
ligament.
Subaxial Cervical Spine

The subaxial cervical spine is most commonly instrumented from an anterior
approach that takes advantage of an anatomic corridor to the spine and
osseous anatomy for safe instrumentation. The cervical vertebrae and neural
foramina of males are typically larger than those of females.21 With
advancing age, cervical vertebrae become wider and more elongated.19 The
average depth of the cervical vertebral bodies ranges from 15 to 17 mm and
increases caudally. Subaxial cervical vertebrae have uncinate processes
extending from the edges of the superior end plates, which form lateral
borders of the intervertebral disk. The uncinate processes form an important
landmark for the lateral extent of anterior decompression procedures.
Posteriorly, the cervical vertebrae are characterized by bifid spinous
processes and large lateral masses, but not the elongated transverse processes
found in the thoracic and lumbar regions. Lateral mass instrumentation is
most commonly used for posterior fixation from C3 through C6 because of
its technical ease and safety.22 The starting point for these screws is 1 mm
medial to the center of the lateral mass. The screws are angulated
approximately 15° cephalad and 30° lateral to limit the risk of injury to the
vertebral artery and exiting nerve roots, although these parameters may
change somewhat depending on the level instrumented and the amount of
spinal degeneration.23 Posterior instrumentation of subaxial cervical pedicles
is possible; however, this is associated with a higher risk of neurologic and
vascular complications compared with lateral mass fixation.24 Many surgeons
limit the use of this technique to C7, where lateral mass fixation is poor and
there is less risk of injury to the vertebral artery. The starting point for C7
pedicle screw instrumentation is the upper outer quadrant of the lateral mass.
The screw trajectory angles medially 25° to 45°. A laminoforaminotomy to
palpate the pedicle may improve the accuracy and safety of this procedure.
Figure 6 The relationship of the vertebral artery to the bony and

neurologic anatomy of the cervical spine.
Thoracic Spine
Several unique anatomic characteristics are important to understand when

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Developed by the North American Spine Society

Charles H. Cho, MD, MBA

Ronald A. Lehman Jr, MD

North American Spine Society

Daniel K. Resnick, MD, MS

Donna Ohnmeiss, PhD

Zoher Ghogawala, MD, FACS

Charles H. Cho, MD, MBA

Mitchel B. Harris, MD, FACS

David R. O’Brien Jr, MD

Mitchell F. Reiter, MD, PC

David Rothman, PhD

Ilyas S. Aleem, MD, MSc, FRCSC

Étienne Bourassa-Moreau, MD, MSc

Joseph S. Butler, PhD, FRCS

Charles H. Cho, MD, MBA

Norman B. Chutkan, MD, FACS

Berdale Colorado, DO, MPH

Marco Ferrone, MD, FRCSC

S. Raymond Golish, MD, PhD, MBA

Clifton W. Hancock, MD, MS, MBA

John A. Hipp, PhD

Keith L. Jackson II, MD

Darnell T. Josiah, MD, MS

Brian J. Kelley, MD, PhD

Brian K. Kwon, MD, PhD, FRCSC

Ronald A. Lehman, Jr, MD

Thomas J. Lotus, DC, FACO, Cert. MDT

Jean-Marc Mac-Thiong, MD, PhD

Isaac L. Moss, MDCM, MASc, FRCSC

Annie O’Connor, MSPT, OCS, Cert. MDT

Donna D. Ohnmeiss, DrMed

Stefan Parent, MD, PhD

Michael L. Reed, DPT, OCS

Daniel K. Resnick, MD, MS

Zeeshan M. Sardar, MD, MSc

Joseph H. Schwab, MD, MS

Paul Sponseller, MD, MBA

Daniel J. Sucato, MD, MS

Michael G. Vitale, MD, MPH

For both learners and specialists working to maintain up-to-date knowledge,

Section 1: Spine Anatomy and Biomechanics

Section 2: Diagnostics in Spine Care

Section 3: Medical Management of Spine Disorders

Section 5: Spine Deformity

Section 7: Neoplastic and Inflammatory Conditions

Section 8: Special Populations in Spine Care

Spine Anatomy and

Musculoskeletal Anatomy and

Keywords: anatomy; applied anatomy; vertebrae

Dr. Moss or an immediate family member is a member of a speakers’ bureau or

Figure 1 Hematoxylin and eosin-stained histologic section of an

The ligamentum flavum is an important anatomic structure to consider

Figure 2 Axial T2-weighted magnetic resonance images of normal

Applied Anatomy by Region

Figure 3 Illustration shows normal global sagittal balance measured

Subaxial Cervical Spine

Figure 6 The relationship of the vertebral artery to the bony and

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