Ebook Principles of deformity correction: Part 1

(BQ) Part 1 book “Principles of deformity correction” has contents: Normal lower limb alignment and joint orientation; malalignment and malorientation in the frontal plane, sagittal plane deformities, osteotomy concepts and frontal plane realignment, oblique plane deformities,… and other contents.

DROR PALEY PRINCIPLES OF DEFORMITY CORRECTION

Springer-Verlag Berlin Heidelberg GmbH

DROR PALEY

CORRECTION

With Editorial Assistance from J E Herzenberg

With More Than 1,800 Separate Illustrations, Clinical Photographs, and Radiographs

DROR PALEY,MD,FRCSC

Director, Rubin Institute for Advanced Orthopedics

Sinai Hospital

Co-Director, The International Center

for Limb Lengthening, Sinai Hospital

Baltimore, MD

Present address:

Rubin Institute for Advanced Orthopedics

Sinai Hospital

2401 West Belvedere Avenue

Baltimore, Maryland 21215-5271, USA

Die Deutsche Bibliothek- CIP-Einheitsaufnahme

Paley, Dror: Principles of deformity correction 1 Dror

Paley.-Berlin; Heidelberg; New York; Barcelona; Hongkong; London ; Mailand ; Paris ; Singapur ; Tokio : Springer, 2002

This work is subject to copyright Ali rights are reserved, whether the whole or part of the material is concerned, specif-ically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks Duplication of this pub-lication or parts thereof is permitted only under the provisions

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© Springer-Verlag Berlin Heidelberg 2002 Originally published by Springer-Verlag Berlin Heidelberg New York in 2002

Softcover reprint of the hardcover 1 st edition 2002 The use of general descriptive names, registered names, trade-marks, etc in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use

Product liability: The publishers cannot guarantee the racy of any information about dosage and application con-tained in this book In every individual case the user must check such information by consulting the relevant literature Cover design: E Kirchner, Heidelberg

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Printed on acid-free paper

~ -

This book is dedicated to the memory of my father, Zvi Paley, who gave so much and asked for so little

Foreword

What is genius? Analyzing complex problems and

find-ing simple ways to explain them in an understandable

manner By this definition, this book is genius

The most dramatic progress in orthopaedic surgery

during the last 2 decades has been in the field of

defor-mity correction The treatment of deformities has

occu-pied and challenged orthopaedic surgeons since

Nicho-las Andry So many brilliant people have worked in this

field Among them, Friedrich Pauwel and Gavril Ilizarov

should be individually named Dr Ilizarov developed

new methods oflimb lengthening and deformity

correc-tion and sparked the newfound interest and

develop-ments in this field today In Dror Paley, this spark

be-came a raging fire

Dr Paley inaugurated many innovations in the field

of deformity correction Among them, his nomenclature

deserves special mention Before his classification based

on joint orientation, we had a plethora of confusing

terminology and definitions leading to a confusion of

language reminiscent of the Tower of Babel Dr Paley's

nomenclature standardizes the terminology in a

man-ner that requires little memorization This logically

based system has gained international recognition and

acceptance as the single language of deformity analysis

and correction This book presents us with these

con-cepts

The principles and concepts outlined in this book

were not discovered or understood overnight They

rep-resent an evolution of Dr Paley's ideas from the past

14 years of clinical work in the field of deformity

correc-tion Unlike other texts, which come and go because they

ic axis planning This has resulted in a long-standing laboration between our two facilities, centered on our common interest in this subspecialty We routinely apply these principles to deformity correction at our center in Germany Many of the new deformity correction devic-

col-es that I and others are dcol-esigning are now based on the CORA principles

Dr Paley'S deformity correction courses around the world have popularized the planning methods and prin- ciples espoused in this book The annual Baltimore Limb Deformity Course is the foundation for this book, work- book, and CD Each of its chapters has been presented as lectures at this course, and the workbook and multime- dia CD have been tested by live audiences at these cours-

es for many years

I am sure this book will become the bible for the standing, diagnosis, and treatment of lower limb defor- mities

Preface

My prediction: this book will become a classic Brave

words, but I can safely make this statement because this

book is not about the latest surgical operation or about

our knowledge of certain pathologies, which is

constant-1y changing Rather, this book presents a system of

de-formity analysis that is universal and applicable to any

past, current, or future surgical osteotomy techniques

and hardware One needs only to think back to medical

school and realize that most of the textbooks that we so

carefully studied are now "of historic interest only:'

Grant's Atlas of Anatomy is perhaps the only book from

my medical school days that I still use I predict that

Pa-ley's Principles of Deformity Correction will also have a

long shelflife The treatment of skeletal deformity is the

heart of our specialty Indeed, the very name of our

spe-cialty, orthopaedics, was coined by Nicholas Andry in

1741 as a word derived from two Greek words, orthos

(meaning straight) and paedis (meaning child) to

indi-cate his goal "to teach the different methods of

prevent-ing and correctprevent-ing deformities of children" (from

Mer-cer Rang's Anthology of Orthopaedics, 1966)

Since Andry's writings 260 years ago, little progress

has been made in understanding, analyzing, and

quan-tifying the types of limb deformities Rarely do we come

across an orthopaedic surgeon who is truly an artist (or

sculptor) Such an individual does not require accurate

preoperative planning to execute a flawless corrective

osteotomy However, for the rest of us journeymen

or-thopaedic surgeons, achieving such beautiful artistic

and aesthetic outcomes is elusive We tend to take a

wedge here or there, by eyeball estimation, and then

rationalize the less than perfect appearance of the final

X-ray "It's not bad" or "it should remodel:' True, there

have been attempts by notable surgeons, such as

Fried-rich Pauwels and Maurice Mueller, to be more precise in

our planning Although we may have received training

in the precise repositioning of fracture fragments with

plates and screws and accurate preoperative planning

and templating for hip osteotomies, what has eluded us

until now is a universally applicable lower extremity

de-formity planning system that takes into account the

en-tire limb, including associated joint compensation and

lever arm considerations: a unified or universal system

that is equally applicable to the diverse range of ages and

he developed the CORA method and to contribute as a co-developer, editor, and author Dr Paley has an uncan-

ny knack of clearly seeing and understanding paedic deformities More importantly, he has a unique ability to then process and integrate this information to make it accessible to the less clairvoyant We have striven to make this method practical and teachable It

ortho-is not hard to learn, but it does take some effort and practice The method is mercifully low-tech: the only tools required are a pencil, ruler, and goniometer We have honed our ability to teach this method during the past 10 years at our annual Baltimore Limb Deformity Course, and many of the figures and cases illustrated in this book have been used in the course The case studies and the artists' diagrams are all derived from our own practices and are representative of deformities that we have treated In this regard, we are greatly indebted to our patients for providing us with both typical and atyp- ical problems to study and illustrate

Interestingly, the CORA method of deformity sis began simply as an attempt to make some sense of the Ilizarov apparatus As the orthopaedic surgeon who in- troduced this method in Canada and the USA, Dr Paley struggled to understand the concept of the Ilizarov hinge, which is what made the Ilizarov fixator so unique

analy-in its ability to correct deformities analy-in a controlled ion In his early experience, he observed some of the sec- ondary deformities that arose from mismatching the lo- cation of the hinge and the CORA In his effort to more accurately identify the level for the Ilizarov hinge, he de- rived the CORA method of mechanical and anatomic axis planning described in this text

fash-He quickly realized that the concept of the CORA and the osteotomy rules were not unique to the Ilizarov de- vice but much more universally applicable to deformity correction by any method Indeed, with the CORA meth-

od, one can understand and plan surgery for any lower extremity deformity from the hip to the foot The gener-

al principle of this book is to first analyze, understand,

and quantify the deformity Only then should you begin

to plan your surgical method and approach Regardless

of which type and brand of fixation is selected (plates,

rods, or external fixator), the basic principles of

defor-mity analysis and planning are the same Failure to

ob-serve these principles frequently results in less than

per-fect alignment and often in secondary deformities that

may be more difficult to correct than the original

defor-mities Ultimately, the surgeon must decide which

de-vice works best in his or her hands The first step of

pre-operative planning, however, is universally required and

beneficial Chap 11 includes a discussion of some of the

vagaries of selected hardware devices, and it is this

chap-ter that will most likely require updating and revision in

a future edition as new device innovations become

avail-able The bulk of the book, however, encompasses

prin-ciples and concepts that will not change because they are

based on simple geometry

Will the CORA method be supplanted by future nology? We think not Even computer-dependent math- ematical modeling of six-axis deformity correction (see Chap 12) is first dependent on the surgeon to accurate-

tech-ly understand, anatech-lyze, and quantify the radiographic deformity We therefore think that the CORA method complements rather than competes with such sophisti- cated deformity correction methods

Is this book the final word on the topic? Clearly not The CORA method is still a work in progress, and there is room to extend its application to the upper extremity, spine, pelvis, and perhaps even maxillofacial deformity correction It has recently been incorporated into com- puter planning software This book has already been

lO years in the making, and these other expansions will have to wait for the second edition We welcome readers' comments, criticisms, and feedback to help us improve future editions

Baltimore, Maryland JOHN E HERZENBERG

-The Story Behind This Book and the CORA Method

My first exposure to orthopaedics was as a medical

stu-dent learning physical examination My patient had a

se-vere limp, which I attributed to weakness of his gluteus

medius What today I would recognize as an obvious

Trendelenburg's gait, in 1977 was the pivotal event that

sparked my interest in orthopaedic surgery I began to

read the works of Rene Caillet (The Biomechanics of

Joints) and of LA Kapandji (Physiology of Joints) Their

books made human mechanics easy to comprehend,

even for a medical student With Principles of Deformity

Correction, I attempt to do the same regarding

deformi-ty analysis and treatment

I am grateful to the many great teachers from my

ortho-paedic residency at the University of Toronto They laid

the foundation for my interest in orthopaedics

Profes-sor Robert Salter set the tone, teaching in a Socratic

manner Dr Alan Gross of Mt Sinai Hospital first taught

me the concept of the mechanical axis of the lower limb

as well as the importance of preoperative planning for

osteotomies of the hip and knee He frequently quoted

Renato Bombelli's Osteoarthritis of the Hip:

Classifica-tion and Pathogenesis - The Role of Osteotomy as a

Consequent Therapy (Springer-Verlag, 1983) and Paul

Maquet's Biomechanics of the Knee: With Application to

the Pathogenesis and the Surgical Treatment of

Osteoar-thritis (Springer-Verlag, 1984), which stimulated me to

read these books on the biomechanics of the hip and

knee, respectively Drs David MacIntosh and Ian

Har-rington taught me controversial concepts of high tibial

osteotomies and alignment Dr Harrington's book on

biomechanics (Biomechanics of Musculoskeletal Injury;

Williams & Wilkins, 1982) and his often misunderstood

article on high tibial osteotomy UBJS 65(2):247-259,

1983] greatly influenced my understanding of concepts

in this field Drs Marvin Tile, Joseph Schatzker, Robert

McMurtry, and James Kellam are responsible for

teach-ing me to think in terms of universal principles rather

than specific surgical techniques Principles to

ortho-paedics are like laws to physics: they remain constant,

whereas specific operations and techniques come and

go

The widest spectrum and complexity of deformity

occur in pediatric orthopaedics in that many conditions

affect the growth and development of the skeleton My teachers at the Hospital for Sick Children, Drs Norris Carroll, Colin Moseley, Mercer Rang, Walter Bobechko, Robert Gillespie, and Robert Salter, provided my initial exposure and understanding of the growth plate and the pediatric skeleton The training I received from them during my residency and fellowship prepared me to challenge many well-established practices and beliefs in pediatric orthopaedics Of all these, I received the great- est support from Dr Norris Caroll, who always had faith

in me and invested his time and patience to teach me meticulous surgical technique and who encouraged me

at times of despair

I acknowledge the support of two of pediatric paedics' elder statesmen, Drs Lynn Staheli and Mihran Tachdjian Dr Staheli, as editor of the Journal of Pediat- ric Orthopedics, invited me to write about current tech- niques of limb lengthening in 1988 UPO 8:73-92, 1988)

ortho-and more recently to write an editorial on deformity correction in the twenty-first century UPO 20:279-281,

2000) Both of these publications helped introduce and heighten awareness to deformity correction principles The late Dr Tachdjian involved me in his international-

ly renowned pediatric orthopaedic review course since

1988 and included my deformity planning method in his textbooks (Pediatric Orthopedics, 1990; and Atlas of Pe- diatric Orthopedic Surgery, 1994) Dr Charles Price, who took over this pediatric course, has included deformity planning by the CORA method as an important theme

of the new course

In November 1983, when I was a third-year paedic resident in Toronto, I met Renato Bombelli who was a visiting professor Dr Bombelli was a disciple of Friedrich Pauwels and a contemporary of Maquet, an- other of Dr Pauwels' disciples Through their writings, I began to understand that complicated joint mechanics could be reduced to simple principles While in Toronto,

ortho-Dr Bombelli briefly mentioned the Ilizarov method This offhand comment sparked my interest in a field to- tally unknown in North America Upon completing my residency in 1985, I visited Dr Maurizio Catagni in Italy

to learn more about the Ilizarov method The next year,

I took my family to Europe and spent 6 months in Italy and the USSR studying limb reconstruction with exter-

nal fixation I learned that deformities could occur in

multiple planes and that hinges could act as the axis of

correction I learned to consider not only angulation but

also translation, rotation, and length when analyzing a

deformity I also learned that deformities could be

cor-rected gradually or acutely and that there were virtually

no limits to how much angulation could be corrected

I visited Kurgan three times during the Soviet era, and

I am greatly indebted to Professor Gavril Abramovich

Ilizarov for the opportunity to study at his institute

Al-though I learned a great deal from Dr Ilizarov's lectures,

articles, and books, he was personally at his best when

examining patients Physical examination was a skill

emphasized in my training in Toronto during the

annu-al physicannu-al examination courses by Mr Alan Graham

Aply Learning Russian facilitated the learning process

and allowed me to speak to the Soviet doctors directly

without going through interpreters Many people in

Kurgan contributed to my education, and some deserve

special mention Igor Kataev taught me the principle of

hinges and of oblique plane deformity Mr Kataev was

not a physician but was in charge of the patent office at

Ilizarov's institute Vladimir Shevtsov, Ilizarov's

succes-sor, answered the questions that I would not dare ask

Ili-zarov He was direct and not evasive Victor Makushin's

ability to clinically evaluate nonunions was uncanny but

could be divined only by reversing the Socratic method

I learned from Dr Tile and the others in Toronto Arnold

Popkov is a master at limb lengthening He took the

mid-dle-of-the-road approach, allowing me to learn by

an-swering my own questions and acknowledging when I

hit upon the correct answers Others helped in a

clandes-tine fashion to overcome the cold war Soviet secrecy of

the institute The best example is Dr Yaakov Odesky, who

is now in Israel He allowed me to see treatments and

concepts that no Westerners had seen before Finally,

Galena Dyachkova's openness helped me to understand

the basic science of the field of distraction, especially

regarding soft tissues

In contrast to the struggle to learn in the USSR, Italy

presented a refreshing sense of openness The team,

comprised of Roberto Cattaneo, Maurizio Catagni, and

Angelo Villa in Lecco, Fabio Argnani in Bergamo, and

Antonio Bianchi-Maiocchi in Milan, welcomed me with

sincerity, kindness, and warmth and did everything to

help me learn I will forever be indebted to them Of

these outstanding teachers, Dr Catagni is most

respon-sible for my current understanding of deformities He

possesses an intuitive understanding of deformities and

essentially computes a CORA analysis in his head as well

as I can on paper My goal with this book was to codify

Dr Catagni's intuitive approach into the objective CORA

method that can be performed in a step-by-step fashion

by all One more important event occurred before all the

pieces were in place When I returned home from Italy

and the USSR and began my pediatric orthopaedic

fel-lowship in Toronto in 1987, I came across an article by

Dr Ken Krackow (Adv Orthop Surg 7:69,1983) This ticle introduced me to the concept of joint orientation angles and was pivotal in my developing the malalign- ment test

ar-With this foundation upon which to build, the CORA method was developed Placing hinges on the Ilizarov device involved putting the hinge just below the ring for metaphyseal deformities and at the apex of diaphyseal deformities It did not make sense that the hinge should always be the same distance from the ring for all meta- physeal deformities For diaphyseal deformities, we al- ways drew two mid-diaphyseal lines and placed the hinge at the intersection of the two lines In the meta- physis, it was not possible to draw a mid-diaphyseal line for the metaphyseal bone segment I struggled with this problem until March 1988, when I had to place hinges for

a supramalleolar osteotomy for ankle varus where the joint line was clearly tilted around the lateral cortex of the joint yet the osteotomy was much more proximal In- stead of placing the hinges just proximal to the distal tib- ial ring, I placed the hinge distal to the ring in what is now recognized as a juxta-articular hinge construct (see Chap 11) To my fascination, the osteotomy site correct-

ed with angulation and translation The osteotomy rules were born together with the CORA method The basic concepts in this book were developed over the next

2 years, based to the greatest extent on the clinical cases

I had the privilege and the challenge to treat but also on

a potpourri of ideas stimulated by colleagues with ilar interests Most notably, Stuart Green from California was my sounding board, especially when it came to post- traumatic deformities Together, we solved the mystery

sim-of the relationship between the planes sim-of angulation and translation I was privileged to have Dr Kevin Tetsworth, who has a brilliant mathematical mind, work with me as

a fellow between 1989 and 1990 In 1990, we published the malalignment test and the first version of the CORA method, although it was not yet called that (Clin Orthop

280:48-64; 65-71) Dr Natsuo Yasui from Osaka, Japan, coined the term CORA method, and it stuck

The initial concept of writing a book about deformity correction originated in 1991 through discussions with Darlene Cooke, who was then a book editor at Williams

& Wilkins The syllabus for the first annual Baltimore Limb Deformity Course served as an outline for the book This course began in 1989, with Ilizarov as a fea- tured guest speaker, and has continued ever since The success of this annual course led me to add more mate- rial and to incorporate the concepts of some very inno- vative contributors who participated in our course Ms Cooke thought that I would never finish the book be- cause I was a perfectionist and continued to add new material every year In many respects, she was right On the other hand, the book was not ready to be finished There were several concepts that were on the verge of

being clarified and that needed to be included in the

book to make it complete For example, the six-axis

de-formity correction concepts introduced by Dr J Charles

Taylor and the lever arm deformity concepts presented

by Dr James Gage In 1998, Williams & Wilkins and I

agreed to drop the book project Without Ms Cooke as

my editor, the external push to complete the book was

gone I saw 10 years of work to produce this book going

to waste I decided upon a new strategy: finish the book

on our own, and then look for a publisher With the help

of our in-house publishing team, Senior Editor Dori

Kelly, Medical Illustrator Joy Marlowe, and Multimedia

Specialist Mark Chrisman, this became a reality It was

now time to seek a new publisher This was easier said

than done I could not get an American publishing

com-pany to share my vision of the importance of this book

The project was finally salvaged by Dr Joachim Pfeil, my

friend and colleague from Wiesbaden, Germany Dr

Pfeil has promoted the CORA method in Europe for

years and has co-authored an article on this subject in

the German language He introduced me to Gabriele

Schroeder, Senior Medical Editor for Springer-Verlag in

Heidelberg in April 2000 This book has finally come to

fruition with the enthusiastic support of

Springer-Ver-lag

This history and my acknowledgments would not be

complete without mentioning a few more people First is

Dr John E Herzenberg, without whose editorial

assis-tance this book would not have been possible Dr

Her-zenberg has been my colleague and friend since we were

fellows together in Toronto in 1985 and 1986 We

contin-ued to correspond and collaborate at a distance until

1991, when Dr Herzenberg moved to Maryland to help

achieve our common dream of developing a limb

lengthening and deformity correction center The

Mary-land Center for Limb Lengthening & Reconstruction

(MCLLR) was born John has been a valuable sounding

board for my ideas for more than 10 years He

encour-aged me to continually strive to simplify my concepts to make them teachable and practical He has been my Co- Chairman in the Deformity Course and my loyal partner

in practice It is often impossible to separate who nated which ideas Therefore, this book is as much a tes- tament to his work as it is to mine Second is Anil Bhave,

origi-PT Mr Bhave has directed our gait laboratory and served as clinical research coordinator since 1992 He has contributed immeasurably to my understanding of gait and dynamic deformities The rest of the loyal staff

of the MCLLR have also contributed to this book in one way or another Kernan Hospital and the Department of Orthopaedics have given me tremendous support and a wonderful environment for my work during the past

14 years lowe them all a great debt of gratitude Finally, I would like to acknowledge my family My wife, Wendy Schelew, and our children, Benjamin, Jonathan, and Aviva, have stood beside me all these years and tolerated my single-minded devotion to completing this project This book is a testimony to their patience, love, and support It is also a testimony to my parents From my mother, a school teacher, I inherited ambition, love for the life sciences, and my skill of teaching My greatest sadness is that my father, who was my role model, will never see this book He was a holocaust sur- vivor who at age 38 (when I was 10) completed his PhD

He was a mechanical engineer who specialized in lurgy, working as a research scientist in Ottawa, Canada, until his untimely death from cancer at age 54 My father was a Renaissance man who spoke nine languages and who stimulated my interest in many fields Most of all, he taught me to think critically He grew up approximately

metal-100 miles from Kurgan in the Soviet Union He never got

to see me complete my residency, raise a family, learn Russian, or achieve the publication of this book It is to his memory that I dedicate this book

Contributing Authors

I am indebted to the chapter contributors, without

whose input this book would be deficient These select

authors were invited because of their original ideas and

contributions to the field of deformity correction The

numbers and titles of the chapters to which they

con-tributed are listed below their names For the

consis-tency of this book, I have edited and added to each of

these chapters to better incorporate these authors' ideas

I especially thank my partner, John E Herzenberg, who

in addition to contributing as an author to two chapters

in the book helped me to develop and also originated

many of the deformity concepts presented herein John

acted as this book's content editor for both the text and

the figures This laborious task has refined and clarified

the theoretical and practical principles that this book

presents

DROR PALEY, MD, FRCSC

ANIL BHAVE,PT

Director of Rehabilitation and Gait Laboratory

The International Center for Limb Lengthening,

Co-Director, The International Center

for Limb Lengthening, Sinai Hospital

Chief of Pediatric Orthopedics, Sinai Hospital

Baltimore, MD CHAPTER 23: Total Knee Replacement and Total

Hip Replacement Associated with Malalignment

MICHAEL SCHWARTZ, PHD Director of Bioengineering Research Gillette Children's Hospital, St Paul, MN Assistant Professor of Orthopaedics University of Minnesota

Minneapolis, MN CHAPTER 22: Dynamic Deformities and Lever Arm

Considerations SHAWN C STANDARD, MD Pediatric Orthopedic Surgeon The International Center for Limb Lengthening, Sinai Hospital

Baltimore, MD CHAPTER 12: Six-Axis Deformity Analysis

and Correction

J CHARLES TAYLOR,MD Orthopedic Surgeon, Specialty Orthopedics Memphis, TN

CHAPTER 12: Six-Axis Deformity Analysis

and Correction KEVIN TETSWORTH,MD Director of Orthopaedics, Royal Brisbane Hospital Brisbane, Queensland, Australia

CHAPTER 13: Consequences of Malalignment

Multimedia Specialist

MARK CHRISMAN,Bs

Drs Dror Paley, MD, FReSe, and John E Herzenberg, MD, FRese

DR 0 R PAL E Y was born in Tel Aviv, Israel, in 1956 and

moved to North America in 1960 He grew up in Ottawa,

Canada, for most of his youth He graduated from the

University of Toronto Medical School in 1979,

complet-ed his internship in surgery at the Johns Hopkins

Hos-pital in Baltimore in 1980, and completed his

ortho-paedic surgery residency at the University of Toronto

Hospitals in 1985 After completing a hand and trauma

surgery fellowship at Sunnybrook Hospital in Toronto

and the AOA-COA North American Traveling

Fellow-ship, he spent 6 months studying limb lengthening and

reconstruction techniques in Italy and the USSR and

then completed a pediatric orthopaedics fellowship at

the Hospital for Sick Children in Toronto This is where

he began his limb lengthening and deformity correction

experience In November 1987, he organized the first

in-ternational meeting on the Ilizarov techniques with Dr

Victor Frankel, at which Professor Gavril Abramovich

Ilizarov shared his knowledge in the United States for

the first time The same month, Dr Paley joined the

or-thopaedic faculty of the University of Maryland Many

of the original concepts for this book were developed

during the next 3 years In 1991, Drs John E Herzenberg

and Kevin Tetsworth joined Dr Paley to form the

ASAMI-In 1990, Dr Paley was awarded a Gubernatorial tion for Outstanding Contributions in Orthopaedic Sur- gery by the Governor of Maryland He was also awarded the Pauwels Medal in Clinical Biomechanics by the Ger- man-Speaking Countries Orthopaedic Association in

Cita-1997 His most cherished award, however, is the paedic Residents Teaching Award, which he has received

Ortho-on more than Ortho-one occasiOrtho-on Dr Paley was the Chief of Pediatric Orthopaedics at the University of Maryland until June 2001 and was Professor of Orthopaedic Sur-

gery at the University of Maryland Medical System until

October 2003 He is well published in the peer-reviewed

literature and has also authored and edited several

books and numerous book chapters He considers

Prin-ciples of Deformity Correction to be his thesis and his

most important academic achievement On July 1,2001,

Dr Paley, together with Drs John Herzenberg, Michael

Mont, and Janet Conway, opened the Rubin Institute for

Advanced Orthopedics at Sinai Hospital, in Baltimore

Dr Paley is the Director of this new orthopaedic center

and Co-Director of The International Center for Limb

Lengthening

Dr Paley is married to Wendy Schelew, and they have

three children (Benjamin, Jonathan, and Aviva) For fun,

he enjoys personal fitness, skiing, scuba diving, biking,

and studying history

JOHN E HERZENBERG was born in 1955 in

Spring-field, Massachusetts At the age of 15, he left to attend high school at Kibbutz Kfar Blum in Israel He studied medicine at Boston University and completed his in-ternship in surgery at Albert Einstein-Montefiore Hos-pitals in New York In 1985, he completed his residency

in orthopaedic surgery at Duke University in Durham,

NC, where he was drawn toward pediatric orthopaedics

by his mentor and chief, Dr J Leonard Goldner

Dr Herzenberg completed a pediatric orthopaedic fellowship at the Hospital for Sick Children in Toronto, where he first met Dr Dror Paley He was on the faculty

at the University of Michigan in Ann Arbor for 5 years, with Dr Robert Hensinger Dr Herzenberg traveled to It-aly' USSR, and Baltimore to study limb reconstruction techniques This began his active collaboration with Dr Paley, which resulted in a joint vision to set up a nation-

al center devoted to limb reconstructive surgery In 1991,

Dr Herzenberg joined Drs Paley and Tetsworth on the full-time faculty of the University of Maryland in Balti-more to establish the Maryland Center for Limb Length-ening & Reconstruction

Dr Herzenberg has traveled extensively, teaching the Ilizarov techniques and the CORA method of deformity planning He has served as president of ASAMI-North America and is active as a volunteer surgeon with Oper-ation Rainbow and Operation Smile, participating in yearly missions to Central and South Americas He was awarded both the AOA-COA North American and ABC Traveling Fellowships He is extensively published in many areas of pediatric orthopaedics and limb recon-struction Dr Herzenberg was Professor of Orthopaedic Surgery at the University of Maryland Medical System until October 2003 and is currently Co-Director of the International Center for Limb Lengthening and Chief of Pediatric Orthopedics at Sinai Hospital

Dr Herzenberg is married to Merrill Chaus, and they have three daughters (Alexandra, Danielle, and Britta-ny) For fun, he enjoys personal fitness and Bible study

Contents

1 Normal lower limb Alignment

and Joint Orientation 1

Mechanical and Anatomic Bone Axes

Joint Center Points

Joint Orientation lines

Ankle

5

5

5 Knee 5

Hip 8

Joint Orientation Angles and Nomenclature 8

Mechanical Axis and Mechanical Axis Deviation (MAD) 10

Knee Joint Orientation 13

Ankle Joint Orientation 16

References 17

2 Malalignment and Malorientation

in the Frontal Plane 19

Malalignment

MAT · 19 · 23

Malorientation of the Ankle and Hip 28

Orientation of the Ankle and Hip in the Frontal Plane 28

MOT of the Ankle 28

References 30

3 Radiographic Assessment

ofLower Limb Deformities 31

Knee 31

Ankle and Hip 40

Radiographic Examination in the Sagittal Plane 46

Knee 46

Ankle 51

Hip 53

Radiographic Examination in One Plane

When There Is a Deformity Component

4 Frontal Plane Mechanical and Anatomic Axis Planning 61

Mechanical Axis Planning 61 Anatomic Axis Planning 63 Determining the CORA by Frontal Plane Mechanical and Anatomic Axis Planning: Step by Step 64 Part I: CORA Method, Tibial Deformities 64

Mechanical Axis Planning

Anatomic Axis Planning

Part II: CORA Method, Femoral Deformities 76

Mechanical Axis Planning

81

97

Angulation Correction Axis (ACA) 99 Bisector Lines 101 Relationship of Osteotomy Type to Bisector Lines 101 Osteotomy Rules 102 Translation and length Displacement

atthe Osteotomy Line 105

Closing Wedge Osteotomy 106

Focal Dome Osteotomy 112 Clinical Choice of Osteotomy Level and Type 114 Multiapical Osteotomy Solutions 140

Single Osteotomy Solutions 140

References 154

6 Sagittal Plane Deformities 155

References · 60 Sagittal Plane Alignment in the lower Limb 155

157

157 Sagittal Plane MAT

Knee Joint Malorientation

Contents

Overall Sagittal Plane MOT

Knee Level Sagittal Plane MOT

Overall Sagittal Plane MOT of the Ankle

Ankle Level Sagittal Plane MOT of the Ankle

Sagittal Plane Anatomic Axis Planning

ofTibial Deformity Correction

Sagittal Plane Anatomic Axis Planning

of Femoral Deformity Correction

Osteotomies in the Sagittal Plane

References

7 Oblique Plane Deformities 175

Plane of Angulation

Graphic Method

Graphic Method Error

Base ofTriangle Method

Axis of Correction of Angulatory Deformities

Two Angulations Equal One Translation

Translation Effects on MAD

Osteotomies for Correction

ofTranslation Deformity

Combining Angulation and Translation

a-t Deformities and MAD

Graphic Analysis of a-t Deformities

Type 1: Angulation and Translation

in the Same Plane

Anatomic Plane Deformity

Oblique Plane Deformity

Type 2: Angulation and Translation

· 203

· 205

· 205 205

· 205 208

in Different Planes · 209

Anatomic Plane Deformity with Angulation

and Translation 90° Apart 209

Oblique Plane Deformity with Angulation

and Translation 90° Apart 211

One Anatomic and One Oblique Plane

Deformity with Angulation and Translation

in Different Planes Less Than 90° Apart 214

Oblique Plane Deformity with Angulation

and Translation Less Than 90° Apart 216

Osteotomy Correction of a-t Deformities 218

Osteotomy Correction of Angulation

and Translation in the Same Plane 219

Correction of Angulation and Translation

for Rotation Deformities 249 Factoring in Rotation for Mechanical Axis

Planning of the Femur 250 Frontal Plane Anatomic Axis Planning

for Rotation Deformities 252 Combined Angulation and Rotation Deformities 252 Locating the Inclined Axis 259 Locating the Inclined Osteotomy 261 Inclined Focal Dome Osteotomy 266 Clinical Examples 266 References 268

10 Length Considerations: Gradual Versus Acute Correction of Deformities 269

Length Considerations for Angular Corrections 276 Neurovascular Structures 278 Nerves 282

Opening Wedge Osteotomy Angulation-Translation Osteotomy

Dome Osteotomy

Hardware Plate Fixation Intramedullary Nails

External Fixation

Order of Correction Lever Arm Principle

Method of Osteotomy References

· 383

· 387

· 389

· 410

12 Six-Axis Deformity Analysis and Correction

CORAsponding Point Method

Virtual Hinge Method

Line of Closest Approach (LOCA)

422 424 Taylor Computer-assisted Design

(CAD) Software

· 426

· 429 Reference Concepts 429

Rate of Correction and Structure at Risk (SAR) 430

Parallactic Homologues of Deformity:

Proximal versus Distal Reference Perspective 433

Animal Laboratory Models

Cadaver Laboratory Models

Clinical Longitudinal Studies

Summary

· 438 440

· 443 444 444 446

Varus plus Medial Collateral Ligament Pseudo laxity 495 Medial Compartment Osteoarthritis

Varus plus Lateral Collateral Ligament Pseudo laxity 497 Medial Compartment Osteoarthritis

Varus plus Rotation Deformity 497 Medial Compartment Osteoarthritis

Varus plus Hyperextension 499 Medial Compartment Osteoarthritis

Varus plus Fixed Flexion Deformity 502 Medial Compartment Osteoarthritis

Varus plus Lateral Subluxation 503 Medial Compartment Osteoarthritis

Varus plus Medial Plateau Depression 503

Lateral Compartment Osteoarthritis (LCOA) 504

References 507

17 Sagittal Plane Knee Considerations 509

Frontal Plane Knee Considerations FFD ofthe Knee

HE and Recurvatum Knee Deformity Knee Extension Contracture Patella Baja and Alta

References

18 Ankle and Foot Considerations 571

Frontal Plane Ankle Deformities

Supramalleolar Osteotomy for Varus

and Valgus Deformities 579

Sagittal Plane Ankle Deformities 581

Supramalleolar Osteotomy for Recurvatum and Procurvatum Deformities 585

Compensatory Mechanisms and Deformities:

Mobile, Fixed, and Absent 596

DIll Contents

Specific Ankle Malalignment Deformities 611

Ankle Fusion Malunion 611

Flattop Talus Deformity 611

Ball and Socket Ankle Joint 619

Overcorrected Clubfoot and Other Lateral Translation Deformities of the Heel

Posterior Tibial Tendon Dysfunction

Completely Stiff Foot Treatment by Supramalleolar Osteotomy

Partial Growth Arrest

Malunion of Fibula

Ankle Contractu res References

19 Hip Joint Considerations 647

Limb in Neutral Alignment to Pelvis, No Intra-· 623 627

· 627 · 630 · 630 630

645

or Periarticular Limitation of Range of Motion 647 Varus Deformity 647

Valgus Deformity 653

Limb in Neutral Alignment to Pelvis, Intra-articular Limitation of Range of Motion 653

Varus Deformity 653

Valgus Deformity 653

Lesser Trochanter Considerations 656

Greater Trochanter Considerations 660

Sagittal Plane Considerations 672

Deformities of the Head and Neck of the Femur 673

Pseudo-subluxation of the Hip 684

Deformities Due to Hip Ankylosis and Arthrodesis between the Femur and the Pelvis 686

Pelvic Support Osteotomy References

20 Growth Plate Considerations 695

LLD

689 · 694 695

Predicting LLD 695

Multiplier Method 697

Additional Growth Databases 701

Relationship of Multipliers for Boys to Multipliers for Girls 701

Development of the Multiplier 702

Limb Length Discrepancy Prediction Formulae 702

Prediction of Limb Length Discrepancy at Skeletal Maturity Using the Multiplier Growth-Remaining Method for Cases of Postnatal Developmental Discrepancy 702

Percentage of Total Bone Growth from the Distal Femur and Proximal Tibia 703

Using the Multiplier Method to Calculate Timing for Epiphysiodesis 703

Growth Prediction Controversies 704

Growth Plate Considerations Relative to Deformity 705

Cause of Deformities 705

Developmental Angular Deformities 705

Angular Deformities: Gradual Correction by Hemi-epiphysiodesis 708

Planning for Hemi-epiphyseal Stapling for Angular Correction at the Knee in Children 708 Multiplier Method for Timing Hemi-epiphyseal Stapling for Correction of Angular Deformity 710

Multiplier Method for Calculating When to Remove Hemi-epiphyseal Staples in Young Children 710

References 715

21 Gait Considerations 717

Gait Considerations in Association with Lower Limb Deformities Sacrifice ofJoint Motion

Fixed Joint Position

Abnormal Loading ofJoints

Compensatory Mechanisms

Frontal Plane Malalignment

Distal Tibia Varus or Valgus

Varus Deformity at the Knee Valgus Deformity of the Knee

Varus or Valgus Deformity of the Proximal Femur

Sagittal Plane Deformity

Ankle Equinus Deformity

Excessive Ankle Dorsiflexion or Calcaneus Deformity

Ankle Arthrodesis Deformities Anterior Translation of the Foot Fixed Flexion Deformity of the Knee Recurvatum of the Knee

Hip Flexion Deformity

Hip Fusion

Rotational Malalignment

Leg Length Considerations

References

22 Dynamic Deformities and Lever Arm Considerations 761

Levers

Mechanical Advantage Moments and Motions Redundancy

Normal Function

· 717

· 717 · 718 · 721 · 721 · 722 · 722 · 725 · 732 · 735 · 738 · 739 · 743 · 744 · 746 · 749

· 751

· 751

· 752 · 753

· 755 · 758

· 761 · 763 · 763 · 765 · 766 Introduction 766

Mechanics of the Ankle: First Rocker 766

Mechanics of the Ankle: Second Rocker 766

Mechanics of the Ankle: Third Rocker 767

Force Production and Compensation

Pathological Function

Short Lever Arm

Flexible Lever Arm

Malrotated Lever Arm

Unstable Fulcrum

Positional Abnormalities

References

23 TKR and Total Hip Replacement

Associated with Malalignment 777

Normal Alignment Versus Malalignment

in Association with Total Knee Arthroplasty

Management of Fixed Soft Tissue Deformities

Clinical Assessment

Radiographic Assessment

Intraoperative Placement of Components

and Consequences of Malalignment

Varus Deformities

Valgus Deformities

Flexion Deformity and Contracture

Recurvatum Deformity

Peroneal Nerve Palsy and Operative Release

Trial Reduction after Ligamentous Balancing

Summary of Soft Tissue Balancing Principles

Extra-articular Bone Deformities

Total Knee Arthroplasty after Failed HTO

Preoperative Assessment

Proximal Tibial Osteotomy-Related Problems

forTKR

Proximal Femoral Deformities

and Total Hip Arthroplasty

Preoperative Planning

Soft Tissue Balancing

Bone Deformity Correction

Glossary

ACA angulation correction axis LPFA lateral proximal femoral angle

aJCO anatomic axis to joint center distance MAD mechanical axis deviation

aJCR anatomic axis: joint center ratio MAT malalignment test

aJEO anatomic axis to joint edge distance MCL medial collateral ligament

aJER anatomic axis:joint edge ratio MCOA medial compartment osteoarthritis

aLOFA anatomic lateral distal femoral angle MOA mid-diaphyseal angle

AMA anatomic-mechanical angle mLOFA mechanical lateral distal femoral angle

AP anteroposterior (for radiograph) MM medial malleolus

aPPTA anatomic posterior proximal tibial angle mMOFA mechanical medial distal femoral angle ASIS anterior superior iliac spine MNSA medial neck shaft angle

CORA center of rotation of angulation MPFA medial proximal femoral angle

OMA distal mechanical axis P posterior (when used in conjunction with

GRV ground reaction vector POFA posterior distal femoral angle

IMN intramedullary nail PPTA posterior proximal tibial angle

JLCA joint line convergence angle SA surface area

LAT lateral (for radiographic view only) SCFE slipped capital femoral epiphysis

LCOA lateral compartment osteoarthritis tBL transverse bisector line

LOTA lateral distal tibial angle TKR total knee replacement

CHAPTER 1 _ 111

Normal Lower Limb Alignment and Joint Orientation

To understand deformities of the lower extremity, it is

important to first understand and establish the

parame-ters and limits of normal alignment The exact anatomy

of the femur, tibia, hip, knee, and ankle is of great

impor-tance to the clinician when examining the lower limb

and to the surgeon when operating on the bones and

joints To better understand alignment and joint

orien-tation, the complex three-dimensional shapes of bones

and joints can be simplified to basic line drawings,

sim-ilar to the stick figures a child uses to represent a person

(~ Fig I-I)

Fig.1-1

Axis lines A stick figure can be used as a schematic of a

com-plex three-dimensional image of a person In the same fashion,

axis and joint lines can be used to describe alignment and joint

orientation of the bones and joints of the lower limb

Furthermore, for purposes of reference, these line drawings should refer to either the frontal, sagittal, or transverse anatomic planes The two ways to generate a line in space are to connect two points and to draw a line through one point at a specific angle to another line All the lines that we use for planning and for drawing sche-matics of the bones and joints are generated using one

of these two methods (~Fig.I-2)

a ~ -4t

b

• ~

Fig 1-2a,b

Two methods of drawing a line in space

a Connect two points

b Draw a line through one point at a specific angle to another line

Mechanical and Anatomic Bone Axes

Each long bone has a mechanical and an anatomic axis (~Fig 1-3) The mechanical axis of a bone is defined as the straight line connecting the joint center points of the proximal and distal joints The anatomic axis of a bone

is the mid-diaphyseal line The mechanical axis is always

a straight line connecting two joint center points,

wheth-er in the frontal or sagittal plane The anatomic axis line may be straight in the frontal plane but curved in the sagittal plane, as in the femur Intramedullary nails (IMN) designed for the femur have a sagittal plane arc

to reflect this In the tibia, the anatomic axis is straight in

Mechanical and anatomic axes of bones The mechanical axis

is the line from the center of the proximal joint to the center of

the distal joint The mechanical axis is always a straight line

because it is always defined from joint center to joint center

Therefore, the mechanical axis line is straight in both the

fron-tal and sagitfron-tal planes of the femur and tibia The anatomic

axis of a long bone is the mid-diaphyseal line of that bone In

straight bones (a,c), the anatomic axis follows the straight

diaphyseal path In curved bones (b,d),it follows a curved

mid-diaphyseal path The anatomic axis can be extended into the

metaphyseal and juxta-articular portions of a bone by

extend-ing its mid-diaphyseal line in either direction

both frontal and sagittal planes (~Fig 1-3) Axis lines

are applicable to any longitudinal projection of a bone

For practical purposes, we refer only to the two

anatom-ic planes, frontal and sagittal The corresponding

radio-graphic projections are the anteroposterior (AP) and

lateral (LAT) views, respectively

verse
y, the anatomic axis does not pass through the center

of the knee joint It intersects the knee joint line at the

medi-al tibimedi-al spine

b The femoral mechanical and anatomic axes are not parallel The femoral anatomic axis intersects the knee joint line gen-erally 1 cm medial to the knee joint center, in the vicinity of the medial tibial spine When extended proximally, it usual-

ly passes through the piriformis fossa just medial to the greater trochanter medial cortex The angle between the femoral mechanical and anatomic axes (AMA) is 7±2°

In the tibia, the frontal plane mechanical and tomic axes are parallel and only a few millimeters apart Therefore, the tibial anatomic-mechanical angle (AMA)

ana-is 0° (~Fig 1-4a) In the femur, the mechanical and atomic axes are different and converge distally (~ Fig 1-4b) The normal femoral AMA is 7±2°

an-(HA PT E R 1 Normal Lower Limb Alignment and Joint Orientation _

Joint Center Points

As noted above, the mechanical axis passes through the

joint center points Because the mechanical axis is

con-sidered mostly in the frontal plane, we need to define

only the frontal plane joint center points of the hip, knee,

and ankle (~ Fig 1-5) Moreland et al (1987) studied the

joint center points of the hip, knee, and ankle

For the hip, the joint center point is the center of the

circular femoral head The center of the femoral head

can best be identified using Mose circles Practically, we

can use the circular part of a goniometer to define this

point (~Fig I-Sa)

Moreland et al (1987) evaluated different geometric

methods to define the center of the knee joint They

demonstrated that the center of the knee joint is

approx-imately the same using a point at the top of the femoral

notch, the midpoint of the femoral condyles, the center

of the tibial spines, the midpoint of the soft tissue

around the knee, or the midpoint of the tibial plateaus

(~Fig.l-Sb) Using the top of the femoral notch or

tibi-al spines is the quickest way to mark the knee joint

cen-ter point without measuring the width of the bones or

soft tissues

Similarly, the ankle joint center point is the same

whether measured at the mid-width of the talus, the

mid-width of the tibia and fibula at the level of the

pla-fond, or the mid-width of the soft tissue outline (~ Fig

l-Sc) The mid-width of the talus or the plafond is the

easiest to use

""II Fig 1-5 a-c

a The midpoint of the femoral head is best identified using

Mose circles (i) If these are unavailable, measure the

longi-tudinal diameter of the femoral head and divide it in two

Use this distance to measure from the medial edge of the

femoral head The center of the femoral head is located

where the distance to the medial border of the femoral head

is the same as half of the longitudinal diameter (ii)

Practi-cally, we can use the circular part of a goniometer to define

this point (iii) r, radius

b The midpoint of the knee joint line corresponds to the

mid-point between the tibial spines on the tibial plateau line and

the apex of the intercondylar notch on the femoral articular

surface These points are not significantly different from the

mid condylar point of the distal femur and the mid plateau

point of the proximal tibia (modified from Moreland et al

1987)

C The midpoint of the ankle joint line corresponds to the

mid-point of the tibial plafond measured between the medial

ar-ticular aspect of the lateral malleolus and the lateral

articu-lar aspect of the medial malleolus The mid-width of the

talus and the mid-width of the ankle measured clinically

yield the same point (modified from Moreland et al.1987)

CHAPTER 1· Normal Lower Limb Alignment and Joint Orientation _

Joint Orientation Lines

A line can also represent the orientation of a joint in a particular plane or projection This is called the joint ori- entation line (~Fig 1-6)

Ankle

At the ankle, the joint orientation line in the frontal plane is drawn across the flat subchondral line of the tib- ial plafond in either the distal tibial subchondral line or for the subchondral line of the dome of the talus (~ Fig l-6a) In the sagittal plane, the ankle joint orientation line is drawn from the distal tip of the posterior lip to the distal tip of the anterior lip of the tibia (~Fig.1-6b)

Knee

The frontal plane knee joint line of the proximal tibia is drawn across the flat or concave aspect of the subchon- dral line of the two tibial plateaus (~Fig 1-6c) The frontal plane knee joint orientation line of the distal femur is drawn as a line tangential to the most distal points on the convexity of the two femoral condyles (~ Fig 1-6d) In the sagittal plane, the proximal joint line of the tibia is drawn along the flat subchondral line

of the plateaus (~Fig.1-6e).In the sagittal plane, the tal femoral articular shape is circular The distal femoral

d Distal femoral knee joint orientation line, frontal plane Draw a line tangent to the two most convex points on the femoral condyles

e Proximal tibial knee joint orientation line, sagittal plane Draw a line along the fiat portion of the subchondral bone Distal femoral joint orientation line, sagittal plane Connect the two anterior and posterior points where the condyle meets the metaphysis For children, this is drawn where the growth plate exits anteriorly and posteriorly

9 Neck of femur line, frontal plane Draw a line from the ter of the femoral head through the mid-diaphyseal point of the narrowest part of the femoral neck

cen-h Hip joint orientation line, frontal plane Draw a line from tcen-he proximal tip of the greater trochanter to the center of the femoral head

Growth plate closed

Fig 1-6 a-h

_ CHAPTER 1· NormalLowerLimbAlignmentandJointOrientation

joint orientation can be drawn as a straight line

connect-ing the two points where the femoral condyles meet the

metaphysis of the femur For children, this can be drawn

where the growth plate exits anteriorly and posteriorly

(~ Fig 1-6 f) Alternatively, Blumensaat's line, which can

be seen as a flat line representing the intercondylar

notch, can be used as the joint orientation line of the

dis-tal femur in the sagitdis-tal plane This is particularly useful

for evaluating sagittal plane deformities secondary to

growth arrest problems

Hip

Because the femoral head is round, it is necessary to use

the femoral neck or the greater trochanter to draw a

joint line for hip orientation in the frontal plane (~ Fig

1-6 g) The level of the tip of the greater trochanter has a

functional and developmental relationship to the center

of the femoral head Similarly, the femoral neck

main-tains a developmental relationship to the femoral

dia-physis and femoral head A line from the proximal tip of

the greater trochanter to the center of the femoral head

represents the hip joint orientation line of the hip joint

in the frontal plane Alternatively, the mid-diaphyseal

line of the femoral neck can represent the orientation of

the hip joint (~Fig 1-6h) This is drawn using the

cen-ter of the femoral head as one point and the

mid-diaphy-seal width of the neck as the second point

Joint Orientation Angles and Nomenclature

The joint lines in the frontal and sagittal planes have a

characteristic orientation to the mechanical and

ana-tomic axes For purposes of communication, it is

impor-tant to name these angles These joint orientation angles

have been given various names by different authors in

different publications (Chao et al 1994; Cooke et al

1987,1994; Krackow 1983; Moreland et al.1987) There is

no standardization of the nomenclature used in the

lit-erature This makes communication and comparison

difficult We think that the names used by different

au-thors are confusing, difficult to remember, and not user

friendly The nomenclature used in this text was

devel-oped so that the names could be easily remembered or

even derived without memorization (Paley et al 1994)

In the frontal and sagittal planes, a joint line can be

drawn for the hip, knee, and ankle The angle formed

be-tween the joint line and either the mechanical or

ana-tomic axis is called the joint orientation angle The name

of each angle specifies whether it is measured relative to

a mechanical (m) or an anatomic (a) axis The angle may

be measured medial (M),lateral (L), anterior (A), or

pos-terior (P) to the axis line The angle may refer to the

proximal (P) or distal (D) joint orientation angle of a

nor-or distal tibial angle

d Anatomic axis-joint line intersection points JCDs for the frontal plane

e Anatomic axis-joint line intersection points JERs for the sagittal plane

bone (femur [F] or tibia [TD Therefore, the mechanical lateral distal femoral angle (mLDFA) is the lateral angle formed between the mechanical axis line of the femur and the knee joint line of the femur in the frontal plane Similarly, the anatomic LDFA (aLDFA) is the lateral angle formed between the anatomic axis of the femur and the knee joint line of the femur in the frontal plane Sagittal plane angles can just as easily be named For example, the anatomic posterior proximal tibial angle (aPPTA) is the posterior angle between the anatomic axis of the tibia and the joint line of the tibia in the sag- ittal plane

Schematic drawings of the nomenclature of the chanical and anatomic frontal (~Fig 1-7a and b) and

aJCD", piriformis fossa

aJCD '" medial tibial spine 10±5mm

PPTA=81\

(77-84' )

1 a-JEA = 13

a-JER = 1'5

1 a-JER = /2

t'\'~TA = 80'

\ i 78-82' )

(H APTER 1 Normal Lower Limb Alignment and Joint Orientation

sagittal (~Fig 1-7 c) plane joint orientation angles are

shown Each axis line and joint orientation line

intersec-tion forms two angles Either angle could be named with

this nomenclature For example, the mechanical medial

distal femoral angle (mMDFA) and the mLDFA are

com-plementary to each other (they add up to 180°)

Al-though either angle could be used to name the joint

ori-entation angle of the knee to the mechanical axis of the

femur, the mLDFA is the one used in this text (~Fig

1-7a) The angles chosen in this text are those that are

normally less than 90° (normal value of the mLDFA= 87°

and normal value of the mMDFA=93°) If the normal

joint orientation was 90°, such as for the

mechanicallat-eral proximal femoral angle (mLPFA) and mechanical

medial proximal femoral angle (mMPFA), the lateral

an-gle was chosen as the standard anan-gle in this text When

it is obvious that the joint orientation angle refers to the

mechanical or anatomic axis, the m or a prefix can be

omitted For example, sagittal plane orientation angles

usually refer to the anatomic axis because mechanical

axis lines are rarely used in the sagittal plane The prefix

m or a is omitted because anatomic axis is implied

Be-cause the mechanical and anatomic axes of the tibia are

parallel, the medial proximal tibial angle (MPTA) and

lateral distal tibial angle (LDTA) have the same value

whether they refer to the mechanical or anatomic axis It

therefore does not matter whether the prefix m or a is

used Finally, because LPFA is used by convention to

de-scribe joint orientation of the hip relative to the

mechan-ical axis and MPFA is used relative to the anatomic axis,

the m and a prefixes can be omitted Therefore, the only

time the m or a prefix must be used is with reference to

the LDFA The mLDFA and the aLDFA are both

normal-ly less than 90° and are different from each other

There-fore, the prefix should always be used to define which

LDFA is being referenced

The angle formed between joint orientation lines on

opposite sides of the same joint is called the joint line

convergence angle OLCA) (~Fig 1-7a and b) In the

knee and ankle joints, these lines are normally parallel

Two mid-diaphyseal points define anatomic axis

lines The intersection of the anatomic axis with the joint

line is fairly constant and is important in understanding

normal alignment and in planning for deformity

correc-tion The distance from the intersection point of

ana-tomic axis lines with the joint line can be described

rel-ative to the center of the joint line or to one of its edges

In the frontal plane, the distance on the joint line

be-tween the intersection with the anatomic axis line and

the joint center point is called the anatomic axis to joint

center distance (aJCD) (~Fig 1-7d) In the sagittal

plane, the distance between the point of intersection of

the anatomic axis line with the joint line and the

anteri-or edge of the joint is called the anatomic axis to joint

edge distance (aJED) The anatomic axis:joint edge ratio

(aJER) is the ratio between the aJED and the total width

Shave et al unpublished results 4.1 ± 4 mm Paley et aI., 1994 9.7 ± 6.8 mm

of the joint Similarly, the anatomic axis: joint center ratio (aJCR) is the ratio of the aJCD and the total width

of the joint The normal values and range are illustrated (~ Fig.1-7e)

Mechanical Axis and Mechanical Axis Deviation (MAD)

The normal relationship of the joints of the lower tremity has been the focus of several recent studies (Chao et al.1994; Cooke et al.1987, 1994; Hsu et al.1990; Moreland et al 1987; Paley et al 1994) There are two considerations when evaluating the frontal plane of the lower extremity: joint alignment and joint orientation (Paley and Tetsworth 1992; Paley et al 1990) Alignment refers to the collinearity of the hip, knee, and ankle (~ Fig 1-8a) Orientation refers to the position of each articular surface relative to the axes of the individual limb segments (tibia and femur) (~Fig 1-8b) Align- ment and orientation are best judged using long stand-

ex-b

d

Shave et aI , unpublished results 6.85 ± 1.4'

CHAPTER 1· NormalLower Limb AlignmentandJoint Orientation

c

Mechanical tibiofemoral angle

Shave et aI., unpublished results Chao et aI., 1994

1.3 ± 1.3' 1.2 ± 2.2'

1 ± 2.8'

1.2 ± 2.2' 1.3 ± 2'

Cook et aI., 1994 Hsu et aI., 1990 Moreland et aI., 1987

Fig 1-8 a-d

a MAD is the perpendicular distance from the mechanical

ax-is line to the center of the knee joint line The frontal plane mechanical axis of the lower limb is the line from the center

of the femoral head to the center of the ankle plafond The normal mechanical axis line passes 8 ± 7 mm medial to the center of the knee joint line

b Knee joint malorientation is present when the angle between the femoral and tibial mechanical axis lines and their respec-tive knee joint lines (LDFA and/or MPTA) falls outside of normal limits (normal=87.5±2°)

c Tibiofemoral mechanical alignment refers to the relation tween the mechanical axes of the femur and tibia (normal = 1.3° varus)

d Tibiofemoral anatomic alignment refers to the relation tween the anatomic axes of the femur and tibia

be-_ CHAPTER 1· NormalLowerLimbAlignmentandJointOrientation

ing AP radiographs of the entire lower extremity on a

single cassette (described in greater detail in Chap 3), so

that one can also assess the MAD

In the frontal plane, the line passing from the center

of the femoral head to the center of the ankle plafond

is called the mechanical axis of the lower limb ( Fig

1-8 a) By definition, malalignment occurs when the

cen-ter of the knee does not lie close to this line Although

normal alignment is often depicted with the mechanical

axis passing through the center of the knee, a line drawn

from the center of the femoral head to the center of the

ankle typically passes immediately medial to the center

of the knee Moreland et al (1987) reviewed long

stand-ing AP radiographs of both lower extremities in 25

normal male volunteers and documented that the center

points of the hip, knee, and ankle are nearly collinear

The angle between the mechanical axis of the tibia and

femur (tibiofemoral angle) was 1.3 ± 2° varus ( Fig

1-8c) A commonly measured value is the anatomic

ti-biofemoral angle This is usually approximately 6°

val-gus ( Fig 1-8d) Hsu et al (1990) reviewed long

stand-ing AP radiographs of the lower extremity of 120 normal

volunteers of various ages and reported that the

me-chanical axis generally passes immediately medial to the

center of the knee In their population, the mechanical

tibiofemoral angle measured 1.2 ± 2.2° varus In a study

of 50 asymptomatic French women older than 65 years

(Glimet et al 1979), the mechanical tibiofemoral angle

measured 0° Most recently, Bhave et al (unpublished

re-suIts) studied a group of 30 adults older than 60 years, all

of whom had no history or evidence of injury, surgery,

arthrosis, or pain in their lower extremities The

me-chanical tibiofemoral angle measured 1.3 ± 1.3°

The distance between the mechanical axis line and

the center of the knee in the frontal plane is the MAD

The MAD is described as either medial or lateraL

Medi-al and laterMedi-al MADs are Medi-also referred to as varus or vMedi-al-

val-gus malalignments, respectively In a retrospective study

of 25 knees in adult patients of different ages, the normal

MAD was 9.7±6.8 mm medial (Paley et aL 1994) ( Fig

1-8a) In a recent prospective study of normal lower

limbs in people older than 60 years without any evidence

of pathological abnormality of the knee, the MAD was

4.1 ±4 mm (Bhave et aL, unpublished results)

Hip Joint Orientation

Previously, hip joint orientation was evaluated using the

neck shaft angle (NSA) The normal NSA is 125°-131°

In an anatomic study of isolated cadaver femora,

Yoshi-oka et al (1987) determined that the NSA in adult men

normally measures 129° ( Fig 1-9) A line from the tip

of the greater trochanter to the center of the femoral

head was described by Paley and Tetsworth (1992) to

de-fine the orientation of the hip in the frontal plane Chao

Shave et aI , unpublished results Paley et aI., 1994

Yoshioka et aI., 1987

Fig 1-9

122 ± 2.6' 129.7 ± 6.2' 129'

Hip joint orientation in the frontal plane MNSA according to different authors (mean ± 1 standard deviation [SD])

Shave et aI., unpublished results 89.4 ± 4.8' Chao et aI , 1994 94.6 ± 5.5' Paley et aI., 1994 89.9 ± 5.2'

Fig.l·10

Hip joint orientation in the frontal plane LPFA according to different authors (mean ± 1 SD)

CHAPTER 1 · NormalLower Limb AlignmentandJoint Orientation _

Bhave et aI., unpublished resu lts

Distal femoral knee joint orientation in the frontal plane

mLDFA according to different authors (mean ± 1 SD)

et al (1994) also measured the LPFA, which they called

the horizontal orientation angle for the proximal femur,

from long standing radiographs in 127 normal

volun-teers and stratified the study group according to age and

gender There was no significant change noted with age

in women, and the relationship of this line to the

mechanical axis of the femur measured 91.S±4.6° in

younger women and 92.7 ± 4.9° in older women In men,

the relationship of this line relative to the mechanical

axis of the femur demonstrated an age-related tendency

toward increasing varus, measuring 89.2 ± 5.0° in

young-er men and 94.6 ± SS in oldyoung-er men Data from our

insti-tution (Paley et al 1994), based on a smaller group of 25

asymptomatic adults, revealed that this proximal

femo-ral joint orientation line measures 89.9 ± 5.2° Another

study from our institution (Bhave et al., unpublished

results) of asymptomatic older adults (>60 years)

with-out gonarthrosis revealed an LPFA of 89.4±4.8° Based

on these observations, we consider 89.9 ± 5.2° to be the

normal LPFA (Paley and Tetsworth 1992; Paley et al

1990, 1994) (~Fig 1-10)

Bhave et aI , unpublished results Chao et aI., 1994

Cooke et aI , 1994 Paley et aI , 1994

Fig 1-12

88.3 :1: 2' 87.5 :1: 2.6' 86.7 :1: 2.3' 87.2 :1: 1.50

Proximal tibial knee joint orientation in the frontal plane MPTA according to different authors (mean ± 1 SD)

Knee Joint Orientation

Regarding knee joint orientation, Chao et al (1994) termined that the distal femoral articular surface is nor- mally in slight valgus relative to the femoral mechanical axis, measuring 88.1 ± 3.2° These results were confirmed

de-by our data (Paley et al 1994), with the distal femur in slight valgus relative to the mechanical axis of the femur (mLDFA=87.8± 1.6°) Cooke et al (1987,1994) obtained radiographs of the knee and hip after positioning the patient in a QUE STAR frame to improve reproducibility

of the radiographic technique In 79 asymptomatic young adults, the distal femoral orientation line mea- sured valgus of 86±2.1° In one study of older asymp- tomatic adults (Bhave et al., unpublished results), the LDFA was 88.1 ± IS Based on all these studies, we con- sider the normal mLDFA to be 87.5±2S (Paley et al

1994) (~Fig.l-ll)

To consider the proximal tibial joint orientation, Chao et al (1994) again stratified their data by age and

_ (H APTER 1 • Normal Lower Limb Alignment and Joint Orientation

gender and found a significant difference when

compar-ing older with younger men In all groups, the proximal

tibial joint orientation line measured slight varus

rela-tive to the mechanical axis of the tibia (87.2 ± 2.1°) In

women, there was no age differential In asymptomatic

young men, there was slightly more varus (MPTA = 85.5

±2.9°) compared with asymptomatic older men (87.5

±2.6°) These data suggest that some young men with

more varus later develop symptomatic degenerative

ar-throsis and "drop out" of the asymptomatic group of

older men This hypothesis is supported by data

regard-ing alignment of elderly normal lower limbs with no

previous history of injury or surgery and with no

evi-dence of knee arthrosis or pain One study (Glimet et al

1979) of 50 elderly asymptomatic French women

docu-mented that the mechanical tibiofemoral angle in this

select group measures 0° instead of slight varus as is

seen in the normal population The second study, from

our institution (Bhave et al., unpublished results),

dem-onstrated an MPTA of 88.3 ± 2° in patients older than

60 years Cooke et al (1994) reviewed standardized

ra-diographs obtained using a positioning frame and

found that the MPTA is 86.7±2.3° These results were

confirmed by our data (Paley et a1.1994), with an MPTA

of 87.2° varus ± IS, and by the data presented by

More-land et al (1987), with an MPTA of 87.2° varus± IS

Based on these observations, we consider the normal

MPTA to be 87±2S (Paleyet al 1994) (~Fig 1-12)

The knee joint orientation measures approximately

3° off the perpendicular, such that the distal femoral

joint line is in slight valgus and the tibia is in slight varus

to the proximal tibial joint line (by convention, we

al-ways refer to the distal segment relative to the proximal

segment when describing deformity of the lower

ex-tremity) (Krackow 1983; Moreland et a1.1987; Paleyet al

1990, 1994) When walking, the feet progress one in front

of the other along the same line, with the leg inclined

(adducted) to the vertical approximately 3° (Saunders et

al 1953) (~Fig 1-13) Krackow (1983) reports that this

3° varus position of the lower limb allows the knee to

maintain an optimal parallel orientation to the ground

during gait (~Fig 1-13 a) In bipedal stance, with the

feet as wide as the pelvis and the tibia perpendicular to

level ground, the knee joint line would be oriented in 3°

valgus relative to the vertical (~Fig 1-13b)

Several authors have presented reports on proximal

tibial sagittal plane orientation Meister et al (1998)

re-ported that the posterior slope of the proximal tibia in

the sagittal plane is 10.7 ± 1.8° (PPTA=79.7 ± 1.8°.) Chiu

et al (2000) reported a PPTA of 78S in a radiographic

study of 25 pairs of Chinese cadaveric tibiae Matsuda et

al (1999), using magnetic resonance imaging, reported

separate PPTAs measured from the medial and lateral

tibial plateaus relative to the anatomic axis of the tibia

They reported a PPTA of 79.3 ± 5° when measured from

the medial tibial plateau and a PPTA of 82±4° when

a

/

: 3°

Midline

b At ease standing position

Midline

Fig 1-13 a, b

a During walking, the limb is in the "at attention" posture, 3°

inclined to the ground Therefore, the knee joint lines are

parallel to the ground during walking (modified from

Kra-kow 1983)

b The standing alignment of the lower limbs to the ground

changes with the feet apart at a distance equal to the width

of the pelvis ("at ease" standing position) and the feet

to-gether ("at attention" standing position) When the feet are

apart, the knee joint line is 3° inclined to the ground and the

mechanical axis is perpendicular to the ground When the

feet are together, the knee joint line is parallel to the ground

and the mechanical axis is oriented 3° to the ground

(modi-fied from Krakow 1983)

Fig.1-14~

Proximal tibial knee joint orientation in the sagittal plane

PPTA according to different authors (mean ± 1 SD)

(HA PT E R 1 Normal Lower Limb Alignment and Joint Orientation _

At attention standing position

(H APTER 1 Normal Lower Limb Alignment and Joint Orientation

PDFA

Shave et ai" unpublished results 83,5 ± 1.9'

Paley et aI , 1994 83.1 ± 3,6'

Fig.1-15

Distal femoral knee joint orientation in the sagittal plane

PDFA according to different authors (mean ± 1 SD)

measured from the lateral plateau In our series (Bhave

et al., unpublished data) of normal volunteers, the PPTA

was 80.4± 1.6° (~Fig 1-14)

The distal femoral knee joint orientation line in the

sagittal plane has never been studied using the joint line

of the distal femur that we describe The normal

poste-rior distal femoral angle (PDFA) in our series of normal

volunteers was 83.1±3.6° (~Fig.1-1S)

The orientation of Blumensaat's line was studied by

Bhave et al (unpublished results) The Blumensaat's line

angle measured 32±2.6° (~Fig.1-16)

Shave et aI., unpublished results 32 ± 2.60

Fig 1-16 Distal femur sagittal plane orientation The angle formed by the distal femoral anatomic axis and Blumensaat's line is shown

Ankle Joint Orientation

Moreland et al (1987) reported that the ankle is in slight valgus (89.8±2.7°) Data from our institution (Paley et

al 1994) also demonstrated slight valgus (LDTA = 88.6 ± 3.8°), as did the data presented by Chao et al (1994) (87.1

± 3.3°) This relationship is variable, and up to 8° of gus can be seen (Moreland et al 1987) Part of this vari- ation may be projectional because, in most studies, this angle was measured from radiographs obtained cen- tered on the knee with the patella forward and without consideration for foot rotation Inman (1976) measured

val-107 cadaver specimens and reported that the average kle joint orientation equated to an LDTA of 86.7 ± 3.2°, with a range of 80°_92° Based on these measurements,

an-we consider the normal LDTA to be 89 ± 3° (Paley and Tetsworth 1992; Paleyet al 1994) (~Fig 1-17) In prac- tice, it is convenient to use the line perpendicular to the tibial diaphysis as the joint orientation line for the ankle

Shave et aI., unpublished results

Ankle joint orientation frontal plane LDTA according to

differ-ent authors (mean ± 1 SD)

Finally, the normal sagittal plane joint line

orienta-tion of the ankle has been described as the anterior tilt

of the distal tibia (~ Fig 1-18) In our studies, the values

were 79.8± 1.60 (Paley et al 1994) and 83.1 ±2.1 0 (Bhave

et al., unpublished results)

References

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C HA PT E R 1 Normal Lower Limb Alignment and Joint Orientation _

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Fig.1-18 Ankle joint orientation sagittal plane ADTA according to dif-ferent authors (mean ± 1 SD)

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