Spinal Instability PDF
Preview Spinal Instability
Contemporary Perspectives in Neurosurgery Series Editor: Robert N. N. Holtzman Contemporary Perspectives in Neurosurgery Series Editor: Robert N.N. Holtzman SurgelY of the Spinal Cord: Potential for Regeneration and RecovelY, Robert N.N. Holtzman and Bennett M. Stein, Editors Spinal Instability, Robert N.N. Holtzman, Paul C. McCormick, lean-Pierre C. Farcy, Editors Endovascular Interventional Neuroradiology, Robert N.N. Holtzman and Bennett M. Stein, Editors Robert N.N. Holtzman Paul C. McCormick Jean-Pierre C. Farcy Editors Heidi Winston Associate Editor Spinal Instability With 181 Figures in 399 Parts Springer-V edag New York Berlin Heidelberg London Paris Tokyo Hong Kong Barcelona Budapest ROBERT N.N. HOLTZMAN, MD Assistant Clinical Professor of Neurological Surgery, College of Physicians and Surgeons of Columbia University; Associate Neurosurgeon, Lenox Hill Hospital, New York, NY 10021, USA PAUL C. MCCORMICK, MD Assistant Professor of Clinical Neurological Surgery, College of Physicians and Surgeons of Columbia University; Assistant Attending, Department of Neuro logical Surgery, The New York Neurological Institute, New York, NY 10032, USA JEAN-PIERRE C. FARCY, MD Associate Clinical Professor of Orthopedics, College of Physicians and Surgeons of Columbia University; Associate Attending, Department of Orthopedics, Columbia-Presbyterian Medical Center, New York, NY 10032, USA HEIDI WINSTON The Harry Winston Research Foundation, 718 Fifth Avenue, New York, NY 10019, USA Library of Congress Cataloging-in-Publication Data Stonwin Conference (8th: 1991: Stonwin Estate) Spinal instabilitylRobert N.N. Holtzman, Paul C. McCormick, Jean Pierre C. Farcy, editors, with Heidi Winston, associate editor; Stonwin Medical Conference; [sponsored by) Harry Winston Medical Foundation, Inc. p. cm.-(Contemporary perspectives in neurosurgery) Includes bibliographical references and index. 1. Spine-Instability-Congresses. I. Holtzman, Robert N.N. II. McCormick, Paul. III. Farcy, Jean-Pierre C. IV. Harry Winston Medical Foundation. V. Title. VI. Series. [DNLM: 1. Joint Instability-surgery-congresses. 2. Laminectomy congresses. 3. Spinal Cord Injuries-surgery-congresses. 4. Spinal Diseases-surgery-congresses. 5. Spinal Fusion congresses. WE 725 S881s 1991) RD771.I58S86 1991 617.3'75-dc20 DNLMJDLC 92-48680 © 1993 Springer-Verlag New York, Inc. Softcover reprint of the hardcover 1st edition 1993 All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer-Verlag New York, Inc., 175 Fifth Avenue, New York, NY 10010, USA), except for brief excerpts in connection with reviews of schol arly analysis. Use in connection with any form of information storage and retrieval, elec tronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. While the advice and information in this book is believed to be true and accurate at the date of going to press, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no war ranty, express or implied, with respect to the material contained herein. Production managed by Natalie Johnson; manufacturing supervised by Jacqui Ashri. Typeset by Asco Trade Typesetting Ltd., Hong Kong. 987 6 5 4 3 2 1 ISBN -13: 978-1-4613-93 28-3 e-ISBN -13 :978-1-4613-9326-9 001: 10.1007/978-1-4613-9326-9 This volume is dedicated to My twin sister, Elizabeth Holtzman, the present comptroller of New York City -RNNH- My wife, Doris, and my son, Paul Jr. -PCMcC- My wife, Pommy, and my children, Frederick, David, and Sarah -J-PCF- Guest of Honor: John P. Kostuik, MD President, North American Back Society Professor of Orthopedic Surgery, Department of Orthopedic Surgery Johns Hopkins Outpatient Center Henry Fleishmann, MD Foreword The Eighth Stonwin Medical Conference provided a unique forum for both orthopedic spine surgeons and spinal neurosurgeons who gathered together in the music room of the Stonwin Estate under the portrait of Edna Winston. There they exchanged views on the nature of spinal in stability and the possible means of correcting that instability so as to preserve spinal mechanical function and to protect the neural tissues housed in its vertebral compartments. The conference represented one of the first of such exchanges where orthopedists and neurosurgeons have formally met to discuss spinal insta bility and to consider the evolution of a new category of surgeon the spine surgeon. It was both controversial and stimulating, and it will serve as a basis for collaborative efforts in the near future. This could not have happened without the generosity of Ronald H. Winston, the son of Harry and Edna Winston, who has unswervingly given support to the exchange of scientific and medical ideas, in part from the influence of his maternal grandfather, Henry Fleishmann, a physician, and in part from his own scientific interests. We are deeply indebted to him for supporting and promoting these conferences as we believe they represent efforts to explore in depth problems on the frontiers of medi cine and surgery. HENRY B. ROBERTS, JR. Publishing and Editorial Consultant Stonwin Medical Conference ix Preface The definition of spinal instability centers on the interrelationships, dis position, and alignment of the vertebrae in both static and dynamic phases. The integrity of these relationships is structurally maintained by the intervertebral cartilaginous joints-the discs with their annulus fibro sis and nucleus pulposus; the zygapophyseal synovial joints; the anterior and posterior spinal ligaments, and to a lesser extent, the intertransverse ligaments, the interspinous ligaments, and the ligamentum flavum. A very important role is played in inertial loading by the paraspinal musculature. The spinal cord and its roots, ganglia, rami, and their individual invest ing membranes generally become involved in the definition by signaling vertebral instability with focal or radicular pain, muscular spasms, or frank neurological symptoms. It is essential to consider these elements along with radiographically documented abnormal motion or position to derive a working definition of spinal instability. The problem is that the definition is not perfectly stated for all in stances. Therefore, judgments about instability are often made on a clinical basis without definitive radiographic correlation. Viewing the spine dur ing the aging process discloses a variety of radiographic appearances that demonstrate vertebral motion but do not reflect true instability. These include the escalator-like steps in a child's flexed cervical spine, the more fixed dynamic lordotic and kyphotic curves in adulthood, and the pseudospondolytic slip of the aged. When there is "clear-cut" abnormal motion in pathological settings of tumor, infection, trauma, and the post operative state seen on flexion-extension radiographs, which demonstrate varying degrees of vertebral displacement from 1 to 3 mm, most spine surgeons will concur on the presence of spinal instability and recommend internal fixation and fusion. On the other hand, when a patient has back pain with spinal stenosis or spondylolisthesis without radiographic evi dence of abnormal translational or rotational motion, some spine surgeons will claim that instability exists and will perform extensive fusions where as others will not, rather opting for decompression of the roots and thecal sac-keeping the fusion as a backup procedure and achieving equivalent xi xii Preface clinical outcomes though perhaps more frequent residual low back pain in the unfused group. Another approach now offered by Dr. Arthur White is to encourage such patients to embark upon a specific spine stabilization training program. It is these less-explicit situations relating to a numerical value of per missible vertebral motion, the presence or absence of pain with such mo tion, and the strict radiographic documentation of abnormal motion that in some instances necessitates examination under general anesthesia, that demand our attention in arriving at a formal definition of spinal in stability. Evolving technology in the form of real-time magnetic reso nance imaging (MRI) capable of performing kinetic imaging of the spine may ultimately be able to prove or disprove stability. At the present time, fusion procedures and fusion technology are rapid ly evolving. Despite the sophistication of the instrumentation, achieving a solid fusion always requires bone grafts as well as metallic constructs via highly complex combined anterior and posterior approaches. Primarily because of this, some guidelines are offered by Dr. Michael Neuwirth, namely, that the ultimate aim of internal fixation be to restore normal function, not to eliminate it with fusion, and when fusion must be per formed under present circumstances it should preserve normal bony and neurologic anatomy while eliminating motion in the shortest segment possible. Of great importance in this regard is further knowledge concern ing the osteointegration of foreign materials to insure the best bony metallic interface possible and the strongest adherence of a given implant to bone. The chapters of this volume address these matters in great detail. Structural integrity of the spine depends on bone growth, bone repair, and ligamentous integrity. Vertebral integrity may be dependent on a glucocorticoid and prostaglandin availability as was suggested from the recent work of the Columbia astronaut, Dr. Millie Hughes-Fulford. Osteoporotic, weakened bone is subject to fracture and it is precisely this susceptibility with ongoing microtrauma and incomplete healing that may be strongly implicated in the progressive instability or pseudospondylo listhesis of aging. Initially the spine may be conceptualized as a structure with five basic motions: forward flexion, backward extension, lateral flexion, rotation, and elongation. Lesser motions include forward and backward wedging of the intervertebral discs and the shearing slippage of one vertebra on another. These basic motions are translated into static and dynamic axial and transverse stability. Axial stability is provided in two columns at Cl C2 and three columns from C2 to the sacrum according to Prof. Rene Louis. The anterior column is formed by the vertebrae and discs and the two posterior columns formed by the two zygapophyseal joints. Transverse stability of one motion segment-level is provided by bony buttresses con sisting of end plates and facets and ligamentous brakes. Further stabiliza-
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