1
`
`NUVASIVE 1025
`NuVasive, Inc. v. Warsaw Orthopedic, Inc.
`IPR2013-00208
`
`

`
`H.V. CROCK PRACTICE OF
`
`SPINAL SURGERY
`
`with a Contribution on The Management of Spinal Injuries by Sir George Bedbrook
`
` 2
`
`

`
`of Spinal Surgery
`With a Contribution on
`
`The Management of Spinal
`Injuries by Sir George Bedbrook
`
`This book presents the man-
`
`agement of major spinal prob-
`
`lems in a new light. Emphasis is
`
`placed on the recognition and
`
`treatmentofthedisablingforms
`
`of disc disease and disc injury,
`
`now be
`
`distin-
`
`uished from the less common
`problems of disc prolapse.
`
`The relevance ofsurgicalanato—
`
`my is highlighted in relation to
`
`individual pathological prob-
`
`lems, and applied anatomy is
`
`integrated with descriptions of
`
`techniques
`
`in each
`
`Disc disorders, spondylolisthe—
`
`sis, spinal canal and nerve root
`
`spinal
`
`infec-
`
`tions,the surgery ofthe cervical
`
`spine, and the management
`
`spinal
`operations,
`{Dre subjects covered by Dr.
`H.V.Crock. Disc prolapse is
`
`placed in a new perspective,
`and this contribution alone may
`
`save many patients from un-
`
`necessary or even disastrous
`
`Spinal surgical techniques are
`described and illustrated in
`
`considerable detail
`
`in
`
`each
`
` 3
`
`

`
` 4
`
`

`
` 5
`
`

`
` 6
`
`

`
` 7
`
`

`
`Henry V Crock
`
`Practice of
`Spinal Surgery
`
`a Contribution on
`
`Managemen
`by Sir George B
`
`Spinal Injuries
`rook
`
`Springer-Verlag
`
`/‘W
`
` 8
`
`

`
`
`
`Henry Vernon Crock, M.D., M.S., F.R.C.S., F.R.A.C.S.
`Senior Orthopaedic Surgeon, St. Vincent’s Hospital, University of Melbourne, Australia
`
`Sir George Bedbrook, Hon.M.D. (Perth), M.S. (Melbourne), F.R.C.S., F.R.A.C.S.
`Senior Orthopaedic Surgeon, Royal Perth Hospital, Western Australia
`
`This work is subject to copyright.
`All rights are reserved, whether the whole or part of the material is concerned, specifically those of translation,
`reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machine or similar means, and storage
`in data banks.
`
`© 1983 by Springer-Verlag/Wien
`Printed in Austria by Manzsche Buchdruckerei, A-1090 Wien
`
`The use of registered names, trademarks, etc. in the 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 publisher can give no guarantee for information about drug dosage and application thereof
`contained in this book. In every individual case the respective user must check its accuracy by consulting
`pharmaceutical literature.
`
`With 234 partly coloured Figures
`
`Frontispiece: From a wood—block by the artist Tate Adams, based on a dissection of the lumbar spine prepared by
`Dr. Carmel Crock.
`
`Library of Congress Cataloging in Publication Data. Crock, Henry Vernon. Practice of Spinal Surgery. Bibliography:
`p. Includes index. 1. Spine—Surgery. 2. Spine—Wounds and injuries. I. Bedbrook, Sir George. II. Title. [DNLM:
`1. Spine—Surgery. 2. Intervertebral disk—Surgery. WE 725 C938p.] RD533.C76. 1983. 617’.375. 83-465
`
`
`
`
`
`_,,’-":3,...,.,.‘~,5;“-4..-.-_,,_-_.:.-...._...._.....-..-...-..---..-.
`
`
`
`
`
` 9
`
`

`
`Foreword
`
`long since surgery of the spine dealt with fracture-dislocation and
`tuberculosis, little else. With the advent of contrast X—ray and anatomical study a
`wide range of disease entities has been categorized and become the subject of
`corrective and ameliorative treatment.
`
`The principal author of the present book has played a distinguished part in
`widening knowledge of the anatomy of the bones, ligaments, blood vessels, neural
`features and the natural history of diseases relevant to hard structure disorder. He
`has done this in relation to the development of highly refined surgical techniques
`based strictly upon structural requirements in relation to the disease processes under
`treatment. The result is a comprehensive account of his integrative conceptualisation
`and the relevant principles of the methods used. His component, the major part of
`the book, is in the tradition of John Hunter, Bland Sutton, Kanavel and others who
`improved their understanding and treatment by the discipline enforced by the
`discipline of basic investigation. In the era of proliferation of specialties and books of
`single author chapters it is refreshing to meet one man’s mind extended.
`By Sir George Bedbrook adding the fruits of his years of experience and thought
`the treatment of spinal injury the book is enriched. As the best of two
`investigative practitioners,
`it reflects the best features of the surgical calling and
`should be studied not only for its material but especially for its reflection of high
`professional endeavour.
`
`Melbourne, June 1983
`
`Professor Emeritus Sir Douglas Wright
`Chancellor, University of Melbourne
`
`
`
`10
`
`

`
`Preface
`
`In writing this book I have attempted to prepare a document which may prove of
`practical use to surgeons in what I see as a phase of transition in spinal surgery.
`This book will be published nearly fifty years after Mixter and Barr’s historic
`description of intervertebral disc prolapse—an entity now in eclipse.
`Since the mid 1950s emphasis has moved to the more common problems of
`spinal canal and nerve root canal stenosis—the latter being caused in some cases by
`quite a different form of disc disease—isolated disc resorption.
`Let us not forget that there are two laboratories from which progress in medicine
`may emanate: the laboratory of the field—clinical practice,
`the chief investigator
`being the busy practitioner; and the other—laboratories of our great medical
`scientific institutions.
`
`In this book I have attempted to focus attention on a particular clinical problem
`described in Chapters 2 and 7 as Internal Disc Disruption. I believe that the study of
`the histochemistry and immunology of internal disc disruption presents a formidable
`challenge for science in the 1980s. This is a challenge which will only be met
`effectively by the joint efforts of clinicians who recognize this disabling entity and
`who can provide fresh disc tissues from their patients for analysis and study by those
`qualified to identify biochemical abnormalities in living tissues.
`' Perhaps that will be the direction of the next leap forward.
`
`Melbourne, June 1983
`
`Henry V. Crack
`
`
`
`11
`
`

`
`Acknowledgements
`
`This book is based on experience gained in the past twenty years in busy practice and
`in orthopaedic research carried out at St. Vincent’s Hospital, in the University of
`Melbourne. I am deeply grateful to the Sisters of Charity for their help in supporting
`
`During that time it has been my pleasure to have many visiting international
`fellows work with me, to all of whom I express my thanks. Among this group I single
`out for special thanks:
`
`Dr. S. Sihombing (Indonesia), Professor P. R. Chari (India), Dr. S. K. Kame
`(India), Dr. A. Fujimaki (Japan), Mr. Robert Venner (Scotland).
`
`Dr. H. Yoshizawa (Japan), co-author of one of my books, has continued to
`
`I wish to thank my orthopaedic colleagues throughout Australia, especially from
`Tasmania, who have referred many difficult cases on which my clinical experience
`has been built. Many of my ideas on the nature of intervertebral disc disorders
`evolved during my association with a remarkable physician, the late Dr. Joseph Silver
`Collings, to whose memory I wish to pay homage.
`
`The following surgeons have kindly given me illustrations for use in this book;
`Messrs. B. J. Dooley, J. Cloke, B. Davie, C. Haw, J. K. Henderson, and K. Mills.
`
`Experience with the use of special surgical techniques such as those required for
`anterior interbody fusion operations, can only be acquired slowly, with help from
`anaesthetists, general and thoracic surgeons. I thank my anaesthetic colleagues for
`their patience, Drs. E. Kenny, J. Forster, W. Stanisich, I. Sutherland, and D. Taylor
`who, from his vantage point at the head of the operating table, has designed an
`excellent retractor for use during these operations.
`
`I am deeply indebted to the following general surgeons; Messrs. P. K. Steedman,
`I. Vellar, B. Collopy, J. L. Connell, and the late E. Ryan. I wish to thank Messrs.
`
`
`
`12
`
`

`
`X Acknowledgements
`
`For permission to reproduce material from my earlier publications, I am
`indebted to:
`
`1. The Medical Journal of Australia, Sydney.
`2. Journal of Bone and Joint Surgery, London.
`3. Clinical Orthopaedics and Related Research, Philadelphia.
`4. Revue de Chirurgie Orthopédique, Paris.
`5. North Holland Publishing Co., Amsterdam.
`6. Butterworths, London.
`The Frontispiece was prepared by Tate Adams of Melbourne, one of the
`greatest living woodblock artists. The author’s portrait on the jacket was drawn by
`Louis Kahan, an old family friend.
`Most of the drawings in this book have been prepared by Dayle Howat. I thank
`him sincerely for his splendid work.
`A number of drawings have been prepared by one of my international Fellows,
`Dr. Hideki Matsuda from Osaka, Japan. He has inherited an artistic talent from his
`father, a talent which he put to good use on my behalf. I thank him sincerely for his
`contributions.
`
`Mr. Bob Morton, of LaTrobe Studios, Pty. Ltd., Melbourne, has helped with
`colour printing.
`For help in the maintenance of my laboratory at St. Vincent’s Hospital, I thank
`particularly Mr. Laurie McMahon and Mr. Fred Green.
`the
`Mr. Dennis Cahill, chief
`technician in the Pathology Department at
`University of Melbourne, has prepared many excellent histological slides for me, and
`for'Mr. Miron Goldwasser, one of my co-research workers.
`in
`Financial support for this work has come from many sources. I thank,
`particular, Mr. R. A. Chappell, Mr. Peter Norris, and Mr. H. D. T. Williamson. I
`thank also the Trustees of the William Angliss Charitable Trust,
`the William
`Buckland Foundation, the Hecht Trust, the National Trustees and Executors Agency,
`and the Rowden White Trust.
`
`To my colleagues in Paris, Professor Jean Cauchoix and Dr. J. Zucman, I
`express particular thanks for their help in translating and facilitating the publication
`of my work on nucleus pulposus calcification.
`Professor R. C. Bennett, Professor of Surgery, St. Vincent’s Hospital,
`Melbourne, has continued to support my work over many years.
`The tedious process of criticism on which the final quality of a manuscript
`depends so heavily has been undertaken once again by my friend, Dr. W.
`McCubbery. The manuscript has also been checked carefully by my wife, Dr. M. C.
`Crock, and by Dr. Paul DiMartino from New York.
`My wife has performed some of the anatomical dissections, photographs of
`which are reproduced in this book. For fifteen years she has assisted at surgery
`during all my private operations. Without her help and the forbearance of my
`children, this book may never have been published.
`My children, Elizabeth and Damian, have helped with secretarial work, Vernon
`with photographic work and Catherine and Carmel with constant encouragement.
`I owe a special debt of thanks to my identical twin brother, Professor G. W.
`Crock of Melbourne.
`
`The preliminary typing of the manuscript was done by my secretary, Mrs. Sandra
`
`
`
`13
`
`

`
`Acknowledgements XI
`
`I am grateful to Professor Emeritus Sir Douglas Wright, Chancellor of the
`University of Melbourne, my former teacher, mentor and friend, who has kindly
`agreed to write the Foreword.
`Finally, I wish to thank my Publishers, Springer-Verlag in Vienna, particularly
`Mr. Frank Chr. May for his untiring help and careful attention to details, and
`especially Dr. W. Schwabl for his constant encouragement.
`
`Henry V. Crack
`
`
`
`14
`
`

`
`Contents
`
`Introduction 1
`
`1. Nerve Root Canal Stenosis 3
`
`9
`
`1.1. Isolated Lumbar Disc Resorption 3
`a) Natural History 3
`b) ) Anatomy of Nerve Root Canals
`i) Normal
`9
`19
`ii) Pathological
`c) Venous Obstruction 20
`(1) Clinical Studies 20
`e) Investigations
`21
`21
`i) Plain X-Rays
`ii) Lumbar Myelography 21
`iii) Lumbar Discography 22
`iv) Computerized Axial Tomography 22
`v) Epidural Venography 23
`f) Operations
`23
`i) Types
`23
`ii) Technique of Lumbar Nerve Root Canal
`Decompression at L5/S1 Level
`23
`1.2. Miscellaneous Causes of Nerve Root Canal Stenosis
`a) Congenital Abnormalities
`28
`b) Space Occupying Lesions
`28
`c) Localized Degeneration 31
`
`28
`
`2. Internal Disc Disruption 35
`
`2.1. Clinical Features
`
`35
`
`
`
`15
`
`

`
`XIV Contents
`
`38
`
`39
`39
`
`56
`
`36
`c) Body Weight Loss
`37
`d) Neurological Signs
`37
`e) Psychiatric Disturbances
`i) Acute Psychotic Reaction 37
`ii) Reaction to Prolonged Disease
`2.2. Pathology 39
`a) Macroscopic Changes
`b) Genesis of Symptoms
`2.3. Investigations 44
`a) Plain X-Ray 44
`b) Discography 44
`c) Myelography
`56
`2.4. Surgical Treatment
`a) Types
`56
`i) Total Disc Excision and Interbody Fusion 57
`ii) Bilateral Nerve Root Canal Decompression
`Laminectomy 57
`_
`iii) Posterior Spinal Fusion 58
`b) Technique of Anterior Lumbar Interbody Fusion 64
`i) Indications 64
`ii) General Pre-Operative Preparation 66
`iii) Positioning 66
`iv) Abdominal Incision 67
`v) Haemostasis
`67
`vi) Preparation of the Interspace for Graft
`Insertion 74
`
`vi) Graft Impaction 82
`viii) Post-Operative Care
`ix) Complications
`83
`c) Results of Anterior Interbody Fusion 85
`
`82
`
`3. Lumbar Disc Prolapses
`
`93
`
`3.1. Introduction 93
`
`3.2. Pathology 94
`3.3. Clinical Features
`
`101
`
`102
`
`101
`3.4. Investigations
`a) Plain X-Rays
`101
`b) Myelography
`102
`c) C.S.F. Examination
`d) Epidurography
`102
`e) Discography
`103
`f)
`Intra-Osseous Spinal Venography
`g) Electrodiagnostic Tests
`103
`103
`3.5. Indications for Surgical Treatment
`3.6. Treatment for Lumbar Disc Prolapses
`a) Discussion
`104
`
`103
`
`104
`
`
`
`16
`
`

`
`105
`
`110
`
`105
`b) Technique
`i) Pre-Operative Preparation
`ii) Anaesthesia
`105
`iii) Positioning
`105
`iv) Instruments
`108
`v) Incision
`110
`vi) Separation of Spinal Muscles
`vii) Opening of Spinal Canal
`115
`viii) Extending Exposure
`116
`ix) Management of Venous Haemorrhage
`x) Excision of Disc Tissue
`117
`xi) Disc Prolapses Associated With Other Spinal
`Problems
`121
`
`Contents XV
`
`116
`
`122
`xii) Upper Lumbar Disc Prolapse
`xiii) Preserving the Bony Canal
`122
`xiv) Wound Closure
`122
`
`
`
`4. Intervertebral Disc Calcification 123
`
`4.1. Introduction
`
`123
`
`123
`4.2. Complications
`4.3. Patterns in Children
`4.4. Patterns in Adults
`
`124
`126
`
`126
`a) Clinical Features
`b) Pathological Findings
`c) Surgical Treatment
`
`133
`133
`
`
`
`5. Spondylolisthesis I35
`
`5.1. Planning of Treatment
`a) History
`135
`138
`b) Physical Parameters
`i) Role of Laminal Pseudarthroses in Symptom
`Production
`138
`
`135
`
`140
`
`ii) State of Discs Adjacent to Slip
`iii) Shape of Spinal Canal
`142
`iv) Degree of Vertebral Slip
`144
`5.2. Technique of Postero-Lateral Inter-Transverse-Alar
`Spinal Fusion
`146
`a) Indications
`146
`b) Preliminary Preparation 147
`c) Positioning
`147
`d) Incisions
`147
`147
`e) Exposure of the Graft Bed
`150
`f) Preparation of Graft Bone
`g) Placement of the Grafts
`150
`
`
`
`17
`
`

`
`
`
`XVI Contents
`
`154
`Infections
`j)
`154
`k) Graft Site Problems
`Spinal Canal and Nerve Root Canal Decompression With
`Foraminal Enlargement
`154
`Direct Repair of the Bony Defects in Spondylolysis and
`Spondylolisthesis
`155
`
`6. The Surgical Management
`of Spinal Canal Stenosis 157
`
`Lumbar Canal Stenosis
`
`157
`
`166
`a) Congenital
`166
`b) Acquired
`Clinical Features
`
`167
`
`169
`
`172
`
`167
`a) Symptoms
`167
`b) Physical Signs
`Radiological ‘Investigations
`a) Plain X-Rays
`169
`b) Computerized Axial Tomography
`c) Lumbar Myelography
`172
`Conservative Treatment
`172
`Surgical Treatment
`172
`a) Positioning
`172
`b) Surgical Pathology
`c) Technique
`173
`173
`i) Exposure
`ii) Enlargement of Bony Canal 174
`iii) Haemostasis
`174
`iv) Dural Opening
`174
`178
`Results of Surgical Treatment for Arachnoiditis
`Recognition and Treatment of Associated Pathological
`Conditions
`178
`
`173
`
`7. Surgery of the Cervical Spine 179
`
`181
`181
`181
`
`Introduction 179
`Indications for Surgery
`a) Cervical Spondylosis
`b) Cervical Disc Lesions
`c) Spinal Injuries
`181
`d) Inflammatory Disorders
`e) Infective Lesions
`182
`182
`f) Tuberculous Infection
`182
`g) Congenital Abnormalities
`Controversial Indications for Surgery After Spinal Injury
`
`182
`
`
`
`18
`
`

`
`Contents XVII
`
`7.5. Technique of Anterior Cervical Interbody Fusions
`a) Instruments
`193
`b) Positioning
`193
`c) Incisions
`193
`199
`d) The Thyroid Gland
`e) Control X-Rays to Identify Individual Intervertebral
`Discs
`199
`
`193
`
`199
`
`f) Preparation of the Dowel Cavity
`g) Graft Preparation 206
`h) Graft Impaction 208
`i) Wound Closure 208
`j) Post-Operative Management 208
`7.6. Radiological Changes After Interbody Fusion 210
`7.7. Complications
`213
`a) Minor 214
`b) Major 214
`
`7.8. ResultsofOperation 215
`
`7.9. Posterior Cervical Spinal Fusion 216
`7.10. Cervical Laminectomy 219
`a) Positioning
`219
`b) Exposure
`219
`c) Post-Operative Care
`
`221
`
`8. Spinal Infections 223
`
`228
`
`223
`
`8.1. Acute Vertebral Osteomyelitis
`a) Introduction 223
`b) Clinical Findings 226
`c) Investigations 226
`d) Radiological Examinations
`i) Plain X-Ray 228
`ii) Computerized Axial Tomography 228
`iii) Myelography 228
`e) Needle Biopsy 228
`f) Treatment
`228
`i) Bed Rest and Chemotherapy 228
`ii) Drainage of Abscesses
`228
`8.2. Tuberculous Disease of the Spine 232
`8.3. Post-Operative Infections 238
`
`9. The Management
`of Failed Spinal Operations 243
`
`
`9.1. Introduction 243
`
`9.2. Investigation 243
`9.3. Outright Failure 244
`
`
`
`19
`
`

`
`XVIII Contents
`
`245
`c) Technical Errors
`i) In Operations for Disc Prolapse 245
`ii) In Operations for Internal Disc
`Disruption 246
`
`9.4. Temporary Relief 247
`a) Failure After Operation for Disc Prolapse
`b) Failure After Operation for Internal Disc
`Disruption 247
`c) Failure After Operation for Isolated Disc
`Resorption 249
`
`247
`
`9.5. Surgical Techniques for Re-Exploring the Spinal
`Canal 252
`
`a) Preparation 252
`b) Radiology 252
`c) Positioning 252
`(1) Instruments
`252
`e) Exposure 252
`f) Orientation 252
`g) Timing of Retractor Application 254
`h) Re-Opening the Spinal Canal 256
`i) Dural and Epidural Problems 257
`i) Meningocoeles
`257
`ii) Unrecognized Epidural Infection 257
`j) Re-Exploration of the Spine Following Spinal Fusion
`Operations
`258
`258
`i) Non-Union of Spinal Grafts
`ii) Graft Overgrowth After Posterior Spinal
`Fusion 260
`iii) Development of Secondary Stenosis Beneath the
`Graft
`260
`iv) Disc or Facet Joint Lesions Above or Below the
`Fused Spinal Segment 260
`v) Fusion at the Wrong Level 262
`vi) Infections 262
`vii) Spondylolysis acquisita 262
`viii) Ligamentum flavum Atrophy 262
`
`9.6. Summary 263
`
`9.7. Post-Operative Care 264
`
`10. Basic Principles in the Management
`of Spinal Injuries
`(by Sir George Bedbrook) 265
`
`
`
`
`20
`
`

`
`Contents XIX
`
`10.3.
`10.4.
`
`Pathogenesis of the Injury 266
`Recognition of the Injury 273
`a) Clinical Examination 274
`i) History 274
`274
`ii) General Assessment
`iii) Examination of the Spine 274
`iv) C.N.S. Examination 275
`b) Radiological
`276
`c) Special Problems 277
`d) Associated Injuries
`279
`
`11.
`
`The Management of Spinal Injuries
`With and Without Neural Damage
`(by Sir George Bedbrook) 281
`
`11.1.
`11.2.
`11.3.
`
`11.4.
`
`11.5.
`11.6.
`
`11.7.
`
`Introduction 281
`
`Transport 282
`Prevention of Secondary and Tertiary
`Complications
`282
`Early Care in the Resuscitation Unit and/or Spinal Cord
`Injury Centre 283
`General Considerations
`
`283
`
`The Role of Special Procedures in Specific Areas of
`Spinal Injury 285
`285
`a) Postural Reduction of the Fracture
`b) Traction, Including Flexion and Extension, Effecting
`Reduction of the Fracture-Dislocation 285
`
`'
`
`c) Manipulative Reduction 285
`d) Open Reduction and Internal Fixation 289
`e) Laminectomy
`289
`289
`f) Use of Exoskeletons
`290
`Management in Specific Areas
`a) Cervico-Dorsal Fractures and Fracture-Dislocations
`in Early Stages 290
`i) Acceleration/Deceleration Injury 290
`ii) Fractures and Fracture-Dislocations from
`C3 to T1
`291
`
`11.8.
`11.9.
`
`b) Lumbo-Dorsal Injuries 293
`Surgical Technique 295
`Indications and Contra-Indications for Specific Surgical
`Procedures
`296
`
`a) Anterior Decompression of Acute Fractures of the
`Cervical Spine 296
`b) Open Reduction and Internal Fixation of
`Lumbo-Dorsal Fractures
`296
`
`
`
`21
`
`

`
`XX Contents
`
`11.10. Management of Problem Cases 297
`11.11. Summary 298
`11.12. Conclusions 298
`
`References 299
`
`Subject Index 309
`
`
`
`22
`
`

`
`Introduction
`
`Nineteen hundred and thirty four marked a turning point in the history of the under-
`standing of sciatica when Mixter and Barr’s paper on rupture of the intervertebral disc
`was published in the New England Journal of Medicine. In 1927 Putti had drawn
`attention to the importance of facet osteoarthritis as a cause of sciatica. His work was
`overshadowed by the impact of the description of prolapse of the intervertebral disc.
`Indeed the entity of prolapsed disc soon emerged as the only intervertebral disc
`lesion which was considered in dealing with the clinical problems of sciatica.
`Dandy (1941) hinted at the need for a wider understanding of intervertebral disc
`pathology in his short paper on “Concealed Ruptured Intervertebral Discs”, but once
`again the profound influence of the concept of disc prolapse held sway and his work
`also was overshadowed.
`In 1957 Morgan and King drew attention to the
`derangement of movement which may occur between adjacent vertebrae due to
`circumferential and incomplete radial annular tears within the discs, as a cause of
`backache. This paper presented an important new concept in the understanding of
`disc pathology applied to clinical practice, yet it failed to receive wide acclaim. The
`biophysical basis of their observations has since been expounded by Farfan et al.
`(1970) in their paper “The Effects of Torsion on the Lumbar Intervertebral Joints:
`The Role of Torsion in the Production of Disc Degeneration.”
`Without doubt, Mixter and Barr’s work, viewed in historical perspective over the
`past 48 years, has exerted a profound effect on the practice of medicine relating to
`the diagnosis and treatment of sciatica. They presented for the first time a simple
`concept to explain the basis of this age-old scourge.
`The impact of this work has been such, that, since its publication, every medical
`graduate in the world has had some familiarity with prolapse of the intervertebral
`
`impact of this work on medical
`Paradoxically the powerful psychological
`practitioners has had a number of adverse reactions. Their acceptance of the concept
`has tended to be blind, so that clinically, they recognize no other disc pathology apart
`perhaps from the vague entity of disc degeneration, widely held to be a cause of back
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`23
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`
` 2
`
`Introduction
`
`diagnosed as being due to disc prolapse. This is particularly so if the patient continues
`to complain of pain after surgery for suspected disc herniation, when none was
`actually found.
`Even among radiologists attitudes have been strongly conditioned, so that many
`think of intervertebral disc pathology exclusively in terms of its capacity to produce
`space—occupying lesions within the vertebral column. Many are not aware of the
`existence of non—prolapsing disc disorders. Likewise, many neurologists have adopted
`a purely mechanical view of disc pathology; as a result, their concept of sciatica due
`to disc disease relates strictly to nerve-root impingement, pain without “signs” being
`beyond their imagined view of the pathology.
`In the 1950s the view prevailed that prolapse of the intervertebral disc was the
`most common cause of low back pain and sciatica, a view which became tradition to
`the detriment of many thousands of patients. Disc prolapses may be the cause of back
`pain and sciatica in only a small percentage of all the patients who complain of those
`symptoms. Sciatica from this cause is usually unilateral and if surgery is indicated, the
`result of excision of the disc fragments is usually excellent. What deserves to be
`recognized is the fact that the results of operations for suspected but non-existent
`disc prolapses are often disastrous.
`The recognition in recent years of a range of disorders of the intervertebral discs
`has made a significant difference to the results of their surgical treatment. Lesions
`such as prolapsed intervertebral disc and isolated disc resorption produce their
`adverse clinical effects mechanically, while others, such as post-traumatic internal
`disc disruption and nucleus pulposus calcification have complex biochemical
`abnormalities which probably cause pain at histochemical levels.
`The four principal disorders of intervertebral discs discussed in the following
`chapters will be presented in order of their frequency in clinical practice.
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`24
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`Nerve Root Canal Stenosis
`
`1.]. Isolated Lumbar Disc Resorption
`
`This condition is characterized by gross narrowing of one affected disc space, with
`sclerosis of the adjacent vertebral bodies. Occurring commonly as an isolated
`affection in an otherwise normal lumbar spine, even late in life, it is seen most
`commonly at L5/S1, occasionally at L4/5 and rarely at L3/4.
`Attention was drawn first to the importance of “reduced lumbo—sacral joint
`space: its relation to sciatic irritation”, by Williams in 1932. The term isolated disc
`resorption was coined by Crock in 1970, though he was unaware of the existence of
`Williams’ paper at that time.
`Isolated disc resorption causes back and leg pain more commonly than does
`prolapse of an intervertebral disc. This condition therefore assumes great clinical
`importance and warrants identification as a specific form of disc disease. By
`combining observations on the pathological findings in isolated disc resorption with a
`sound knowledge of surgical anatomy, different forms of surgical treatment can be
`planned to suit individual cases. When these cases are treated by the standard
`operation of “laminectomy” used in the management of disc prolapse, the results are
`often poor, whereas excellent results may be obtained by performing bilateral nerve
`root canal decompressions or more rarely by performing some form of local spinal
`
`a) Natural History
`
`This condition of narrowing of a single lumbar intervertebral disc space usually
`progresses slowly over a number of years, the clinical course being punctuated by
`repeated bouts of acute low back pain lasting for three to four days and then
`resolving completely. Following trauma, particularly a fall on to the buttocks, the
`symptoms may extend to include severe bilateral buttock and leg pains. In some cases
`buttock and leg pain may be aggravated by physical exercise or walking. The
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`25
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`
`4 Nerve Root Canal Stenosis
`
`Figure 1.1. A lateral radiograph of the lumbar spine of a 48 year-old man showing the
`classical features of isolated disc resorption at the lumbo-sacral junction
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`26
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`27
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`

`
`Figure 1.2c
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`28
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`
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`Figures 1.4a and b. Isolated discresorption at L4/5. A 48 year-old woman had longstanding
`back pain, with bilateral leg pain. She was treated by bilateral nerve root canal decompression
`laminectomy. The L4/5 disc was not disturbed at operation. a Lateral radiograph, and
`b antero-posterior radiograph of the spine showing features of isolated disc resorption at the
`L4/5 level, the vertebral end-plates remaining parallel to each other in (b)
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`29
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`

`
`8 Nerve Root Canal Stenosis
`
`Figure 1.5. A photograph of a mid—line sagittal section of the lumbar spine of a man aged
`69 years. The pathological features of isolated disc resorption are well shown, with vertebral
`end—plate remnants in the posterior two-thirds of the disc space visible on either side of an
`otherwise empty disc space. Note the marked sclerosis of the vertebral bodies on either side
`of the disc space
`
`In parallel with the natural history of the symptoms, repeated radiological
`examination will reveal a progressive loss of disc height at
`the affected level
`(Figs. 1.2 a—c). In the lower lumbar region in adults, the disc height between adjacent
`vertebral end-plates ranges from 10-15 mm. In established cases of isolated lumbar
`disc resorption the height of the intervertebral disc space may be reduced to 3 mm.
`The vacuum phenomenon of Knuttson is another prominent radiological feature
`which may become evident if the X-ray is taken with the patient standing with the
`lumbar spine hyperextended. A black gas shadow will then appear in the disc space.
`Sclerosis of the adjacent vertebral bodies is found, while marginal osteophyte
`formation is minimal. Occasionally a ridge of bone covered with a thin layer of
`annular fibre remnants may be found projecting into the spinal canal (Figs. 1.3-1.5).
`For example at L5/S1 subluxation of the facet joints with intrusion of the superior
`facets of S1 into the intervertebral foramina and lumbar nerve root canals will also be
`
`seen (Figs. 1.6a, b).
`The disc space narrowing which accompanies sacralization anomalies is not to be
`confused with that occurring in isolated lumbar disc resorption.
`
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`30
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`Isolated Lumbar Disc Resorption
`
`9
`
`Figures 1.6a and b. An oblique view of the lower lumbar spine showing normal relationships
`of the facets of the L4/5 level, top marker, and subluxation of S1 up against the pedicle of L5
`on the bottom marker, with an explanatory line drawing alongside
`
`In established cases where the disc space has become very narrow, with parallel
`vertebral end-plate settling, the symptoms of buttock and leg pain, if intractable, are
`usually bilateral.
`Earlier in the course of this disease, a small number of patients may present with
`unilateral sciatica. These patients may exhibit the classic features of neurological
`defects in either L5 or S1 nerve roots. Usually they will be found to have a
`sequestrated fragment of vertebral end-plate cartilage impinging on the affected
`nerve root. This finding is one of the striking features of this disease process. At
`operation in such cases, the disc space is virtually empty and clearly recognizable
`necrotic vertebral end-plate cartilage will be found causing the nerve root
`compression.
`
`b) Anatomy of Nerve Root Canals
`
`i) Normal
`
`The anatomy of the lumbar nerve root canals and intervertebral foramina will be
`described to assist with the understanding of the genesis of the symptoms and signs
`which may occur in cases of isolated disc resorption.
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`31
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`

`
`10 Nerve Root Canal Stenosis
`
`Figure 1.7. A photograph of a dissection of the lower lumbar spine in an adult to show some
`of the relations of the lumbar nerve roots. Note especially the origins of the nerve root sleeves
`from the dural sac and the courses of the nerve roots in relation to the pedicles. (Dissected by
`Dr. M. C. Crock)
`
`
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`32
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`

`
`Isolated Lumbar Disc Resorption
`
`ll
`
`
`
` ~IlllllllIIIII|u.““‘“ 1
`
`
`lumbar
`Figures 1.8. a A sagittal section through the level of the pedicles of a normal
`vertebral spine of an 18 year-old male to show the boundaries and major structural relations
`of the intervertebral foramina. b A line drawing taken from a specimen to show the principal
`relations of the L5 nerve root at the L5;'S1 intervertebral foramen. 1 the nerve root; 2 the
`l-igamentum flavum; and 3 the apex of the superior facet of S1
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`33
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`

`
`12 Nerve Root Canal Stenosis
`
`The lumbar nerves run obliquely downwards and laterally from the lateral
`aspects of the dural sac, emerging at their respective intervertebral foramina and
`lying inferior to the lumbar pedicle in the upper part of each foramen (Fig. 1.7).
`Anomalies excluded, each nerve root is intimately related to the medial and inferior
`aspects of the adjacent vertebral pedicle.
`The intervertebral foramen has fixed boundaries, though its dimensions vary
`depending on the height of the individual disc space and on the size of the related
`facet joints and thickness of the ligamentum flavum (Figs. 1.8a, b). Bounded above
`
`Figure 1.9. A drawing showing the relations of the S1 spinal nerve root canal viewed from
`within the spinal canal
`
`and below by the vertebral pedicles, the floor from above downwards is formed by
`the postero—inferior margin of the superior vertebral body, the intervertebral disc and
`the postero-superior margin of the inferior vertebral body (Fig. 1.9). The roof is
`formed by the ligamentum flavum, terminating at its outer free edge, and posterior to
`this structure lies the pars interarticularis and the apophyseal joint formed between
`the adjacent inferior and superior vertebral facets (Fig. 1.10). The intervertebral
`foramen is analogous to the doorway at the end of a passage, its vertical height being
`determined by the vertical height of the corresponding intervertebral disc space.
`A nerve root canal, by contrast, is a tubular canal of variable length, arising from
`the lateral aspect of the dural sac. Viewed from within the sac, the hiatus through
`which the component motor and sensory nerve roots pass to the spinal nerve has the
`
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`34
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`

`
`Isolated Lumbar Disc Resorption
`
`13
`
`Figure 1.10. A transverse section through the lower lumbar spine at the level of the inter-
`vertebral fora_men, the section passing through the vertebral body. On the left of the specimen
`note the posterior relations of the nerve root. In the mid-line, the cauda equina can be clearly
`seen, easily distinguished from