Ebook Minimally invasive spine surgery techniques, evidence, and controversies: Part 1

(BQ) Part 1 book Minimally invasive spine surgery techniques, evidence, and controversies has contents: The definition of minimally invasive spine surgery and the rationale for its use, the four pillars of minimally invasive spine surgery, posterior foraminotomy,.... and other contents.

AOS_MISS_Book.indb 10/30/12 11:08 AM Roger Härtl  |  Andreas Korge Minimally Invasive Spine Surgery Techniques, Evidence, and Controversies AOS_MISS_Book.indb 10/30/12 11:08 AM AOS_MISS_Book.indb 10/30/12 11:08 AM Roger Härtl  |   Andreas Korge Minimally Invasive Spine Surgery Techniques, Evidence, and Controversies 711 illustrations and images, and 35 cases AOS_MISS_Book.indb 10/30/12 11:08 AM Library of Congress Cataloging-in-Publication Data is available from the publisher Hazards Great care has been taken to maintain the accuracy of the information contained in this publication However, the publisher, and/or the distributor, and/or the editors, and/or the authors cannot be held responsible for errors or any consequences arising from the use of the information contained in this publication Contributions published under the name of individual authors are statements and opinions solely of said authors and not of the publisher, and/or the distributor, and/or the AO Group The products, procedures, and therapies described in this work are hazardous and are therefore only to be applied by certified and trained medical professionals in environments specially designed for such procedures No suggested test or procedure should be carried out unless, in the user‘s professional judgment, its risk is justified Whoever applies products, procedures, and therapies shown or described in this work will this at their own risk Because of rapid advances in the medical sciences, AO recommends that independent verification of diagnosis, therapies, drugs, dosages, and operation methods should be made before any action is taken Although all advertising material which may be inserted into the work is expected to conform to ethical (medical) standards, inclusion in this publication does not constitute a guarantee or endorsement by the publisher regarding quality or value of such product or of the claims made of it by its manufacturer Legal restrictions This work was produced by AO Foundation, Switzerland All rights reserved by AO Foundation This publication, including all parts thereof, is legally protected by copyright Any use, exploitation or commercialization outside the narrow limits set forth by copyright legislation and the restrictions on use laid out below, without the publisher‘s consent, is illegal and liable to prosecution This applies in particular to photostat reproduction, copying, scanning or duplication of any kind, translation, preparation of microfilms, electronic data processing, and storage such as making this publication available on Intranet or Internet Some of the products, names, instruments, treatments, logos, designs, etc referred to in this publication are also protected by patents and trademarks or by other intellectual property protection laws (eg, “AO”, “ASIF”, “AO/ ASIF”, “TRIANGLE/GLOBE Logo” are registered trademarks) even though specific reference to this fact is not always made in the text Therefore, the appearance of a name, instrument, etc without designation as proprietary is not to be construed as a representation by the publisher that it is in the public domain Restrictions on use: The rightful owner of an authorized copy of this work may use it for educational and research purposes only Single images or illustrations may be copied for research or educational purposes only The images or illustrations may not be altered in any way and need to carry the following statement of origin ”Copyright by AOSpine, Switzerland” Check hazards and legal restrictions on www.aofoundation.org/legal Copyright © 2012 by AOSpine, Switzerland, Clavadelerstrasse 8, CH-7270 Davos Platz Distribution by Georg Thieme Verlag, Rüdigerstrasse 14, DE-70469 Stuttgart and Thieme New York, 333 Seventh Avenue, US-New York, NY 10001 ISBN: 978-3-13-172381-9 e-ISBN: 978-3-13-172441-0 AOS_MISS_Book.indb 123456 10/30/12 11:08 AM Foreword Foreword John K Webb FRCS Consultant Spinal Surgeon Centre for Spinal Surgery and Research University Hospital Nottingham NG7 2UH United Kingdom Co-founder and first President of AOSpine The authors are to be congratulated on producing such a comprehensive book on minimally invasive surgical techniques They stress that access strategies should not compromise the goal of the surgical procedure, the importance of the knowledge of the anatomical planes, and an appreciation of the anatomy from the experience of performing open procedures They accept there is a long learning curve and correctly recommend a strategy of performing more straightforward cases at the beginning of a surgeon´s introduction to minimally invasive surgery A concept that many inexperienced surgeons find difficult to acknowledge The importance of the four “pillars” of MISS are emphasized: microsurgical techniques; access strategies to the spine; imaging/navigation techniques; and specialised instruments and implants Some chapters use standard approaches that, with recent technology, have been reduced to very small incisions, while other chapters describe very innovative approaches It is pleasing to see that the basic AOSpine surgical principles have been taken into account when formulating the approaches Even with the drive for all approaches to be minimal, authors include a realistic valuation that, in some cases, MISS techniques could be inappropriate Radiation exposure is a concern and should be closely monitored The book is a comprehensive coverage of all techniques in minimally invasive spine surgery A word of caution, some approaches are very complex and the surgeon will have to be highly skilled, requiring three-dimensional thinking; such techniques may be out of reach for lesser mortals Nevertheless, the descriptions, pictures, and diagrams are excellent and have made the understanding of the approaches very clear This book is beautifully produced and written to a very high standard, a standard one would expect from such eminent surgeons I strongly recommend Minimally Invasive Spine Surgery— Techniques, Evidence, and Controversies to all current and up-and-coming spine surgeons developing their minimally invasive surgical techniques I would go so far as to say this is “a must have” book for such surgeons In fact, it should be on the bookshelf of all spine surgeons V AOS_MISS_Book.indb 10/30/12 11:08 AM Dedication Dedication To Alasha, Sebastian and Julian To Heidrun, Louisa and Daniel For all their love, support, understanding and patience, without which, this book would not have been possible VI AOS_MISS_Book.indb Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies  Roger Härtl, Andreas Korge 10/30/12 11:08 AM Acknowledgments Acknowledgments We would like to thank the many authors, educators, illustrators, designers, project managers, and technical and administrative contributors that worked tirelessly to bring this publication to life • Jeff Wang, Khai Lam, and Frank Kandziora, the original members of the expert group team (together with Roger Härtl and Andreas Korge) for bringing together the ideas for the book • Our illustrious team of authors, from all corners of the world, many juggling professorial and academic positions, and or very busy medical and surgical practices • Kathrin Lüssi and Patricia Codyre and the entire AO Education team, led by Urs Rüetschi • Claas Albers from AOTK; and the AOSpine team, led by Alain Baumann • Amber Parkinson and Michael Gleeson, Project Coordinators • Marilyn Schreier from Syntax language editing • Jecca Reichmuth for scientific illustrations and Roger Kistler for typesetting • Carl Lau, Cristina Lusti, and Susanne Klein for proofreading, and for Susanne's essential administrative work (keeping track of our world traveling authors) • Patrick Hiltpold from AO CID for compiling the evidencebased summaries and PICO analyses • Rosalie Villano from Leica Microsystems, Thomas Kienzle from Richard Wolf Medical Instruments, and Drew Messler from Micro Image Technologies for supplying photos and images • Thieme publishing Roger Härtl Andreas Korge VII AOS_MISS_Book.indb 10/30/12 11:08 AM Introduction Introduction This is the first edition of “Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies” The idea for the book came out of our work in the AOSpine Expert Group on MISS and Navigation, around 2008, where we enthusiastically discussed many of the initial hopes and controversies that surrounded the evolving field of MISS with our esteemed colleagues Jeff Wang, Khai Lam and Frank Kandziora It was clear to all of us that MISS offered exciting and potentially effective treatment strategies for many areas in spinal surgery However, it also seemed to be heavily dominated by a small number of champion surgeons and steered by industry, and not necessarily by the needs of our patients As a consequence, we embarked on an ambitious project to critically explore the possibilities, the current reality, but also the limitations of MISS The final product has greatly surpassed our initial expectations We proudly present a comprehensive, user-friendly and didactic overview of the techniques, indications and controversies of currently utilized minimally invasive techniques and spinal navigation in the cervical, thoracic and lumbar spine for a wide variety of spinal disorders We include critical discussions of the pros and cons of these techniques for our patients, and provide an objective, evidence-based framework of MISS using currently published literature We also acknowledge the importance of the surgeon’s individual experience and wisdom by including surgical pearls and “tips and tricks” from master surgeons and many of the pioneers of MISS The book has been divided into five sections that together cover all areas of MISS: In the “Fundamentals” section, we explore the principles of MISS, its historical development as a consequence of advances made in various subspecialties within surgery, and how its principles perfectly fit the “AO philosophy” The sections following cover technical procedures and the science behind particular MISS approaches based on the anatomic regions: Cervical Techniques, VIII AOS_MISS_Book.indb Thoracic Techniques, and Lumbar Sacral Techniques—both posterior and anterior This comprehensive book not only provides basic concepts, and the latest clinical and scientific research, but it is also case-based with clear photographs, x-rays, MRI, CT scans, and illustrations of anatomy and cases, giving the reader an excellent understanding of the decision-making process, as well as the whole surgical procedure from preoperative planning to recovery In the end, several conclusions can be drawn: • MISS is here to stay; it is a logical consequence of the evolution of surgery, based on advances in at least four areas: microsurgery, navigation, new spinal access strategies, and spinal instrumentation • MISS offers alternative and frequently advantageous treatment options in all regions of the spine, and for most pathologies; it expands our technical capabilities as surgeons and frequently allows the safer and more effective treatment of patients that were previously not considered good surgical candidates for a particular operation • More work is needed; especially in the area of spinal deformity correction The success of minimally invasive spine surgery will depend on the integration of scientific progress, technical expertise, and the surgeon’s individual experience and good judgment • Surgeons have to be willing to learn and evolve; they have to continue to critically and honestly evaluate the pros and cons of MISS as well as their own results in each patient We hope that neurological and orthopedic spine surgeons all around the world can benefit from this first edition of “Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies” to improve care of their patients We are thankful to our colleagues, families and AOSpine for the unconditional and enthusiastic support they have given us throughout the preparation of this book Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies  Roger Härtl, Andreas Korge 10/30/12 11:08 AM Authors  Paul Heini, Mark Kleinschmidt Fig 3.6-4  Placement of guidewire/cannula based on anatomical landmarks The medial border of the pedicle and the posterior wall define the safe corner (red line/red angle) Depending on the final positioning, the angle of approach differs and the skin incision is made according the trajectory planned for the cannula The dotted red arrow indicates to the bilateral approach, while the black arrow indicates the monolateral and more convergent approach a c b 246 AOS_MISS_Book.indb 246 d Fig 3.6-5a–d  For a surgical procedure under local/standby anesthesia, the patient is placed in a prone position on a beanbag that can be adjusted to individual needs Free access for the C-arm in the AP and lateral projection in the area of interest is mandatory A high-quality C-arm is essential The area to be treated is examined before draping, and the levels to be treated are indicated preoperatively It is also possible to install two C-arms to monitor both planes simultaneously Otherwise, it is necessary to switch from lateral to AP monitoring during the cement-filling procedure Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies  Roger Härtl, Andreas Korge 10/30/12 11:12 AM 3  Thoracic techniques 3.6  Vertebroplasty and percutaneous cement reinforcement techniques Surgical technique • • under AP image intensification until its tip reaches the medial border of the pedicle (Fig 3.6-4) If more than one approach is necessary, this step is repeated The position in the lateral projection is checked, and it is ensured that the K-wire is at the level of the posterior wall The position of the guidewire is readjusted, if necessary The filling cannula or working portal is introduced The tip of the filling cannula should reach the anterior half of the vertebral body (Fig 3.6-6) A biopsy is taken if needed A blunt trocar is used to clear the cannula a b c d The surgical steps for vertebroplasty are as follows: • Cannula placement • Preparation of the cement • Cement injection/cannula removal • 6.1 • • Access, cannula placement Placement of the filling cannula or working portal can be either trans- or parapedicular, depending on the patient's specific anatomical characteristics and the chosen sequence for the approach Generally, the approach at the thoracic and upper lumbar spine is performed monolaterally—unless the fracture pattern is special (for instance, a comminuted endplate presents a higher risk of cement leakage)—or unless a kyphoplasty or stentoplasty procedure is planned (Fig 3.6-6) The angulation to approach the center of the vertebral body (VB) is increased (Fig 3.6-4) In the lower lumbar spine, the approach is usually transpedicular and carried out bilaterally, in order to achieve sufficient filling and support for the VB Any percutaneous procedure depends on image-guided navigation The standard modus operandi is the C-arm High-quality equipment is desirable, and a combination of two C-arms can ease and speed up the procedure, although this is not mandatory (Fig 3.6-5) Also, CT guidance is used, or the intervention is performed, in the angiography suite For cement injection, real-time monitoring is crucial For cannula placement, computer-guided navigation is described The procedural steps are as follows: • After patient positioning, the site to be treated is examined with the C-arm, ensuring that the anatomical landmarks are clearly visible in both planes (Fig 3.6-4) • The levels and points of entry are indicated • Disinfection and surgical draping are performed • The C-arm is introduced in strict AP projection, the beam adjusted parallel to the endplates, identify the pedicle • Local anesthesia is injected into the skin in the projection of the pedicle and around the periosteum of the transverse process/facets (about cc) • A stab incision is made according the planned trajectory • Stepwise placement of a mm guide wire then follows: when the guide wire tip touches the bony surface, the starting point is usually lateral to the outlines of the pedicle, thus achieving sufficient convergence If a monolateral approach is chosen (according the preoperative planning), the starting point is located up to 1.5 cm lateral of the pedicle eye The guidewire is advanced • Fig 3.6-6a–d  Cement injection under continuous lateral C-arm monitoring The appearance of the cement at the tip of the cannula must be observed very carefully If the cement disperses in any direction away from the tip, this indicates direct connections to vascular channels in the bone Then 45 to 180 seconds should elapse before applying another small amount of cement The cement should be injected in a stepwise fashion, and build up gradually After the first cc have been injected, checking via AP C-arm monitoring should be performed Following this, cement injection can be continued with the C-arm in the lateral projection Once resistance to the injection becomes apparent, the trocar can be used to push in the remaining cement This ensures controlled application of the cement At any sign of leakage, the injection must be stopped immediately 247 AOS_MISS_Book.indb 247 10/30/12 11:12 AM Authors  Paul Heini, Mark Kleinschmidt 6.2 Cement preparation There are several cement formulas on the market that are specially designed for vertebroplasty They have an increased radiopacity and longer working time at the optimal viscosity level Some of these cements are ready for immediate use, others require several minutes before they can be injected It is important to be aware of the temperature sensitivity of the setting time High viscosity is a crucial factor for controlling cement leakage 6.3 a significant height loss (Fig 3.6-7, Fig 3.6-8) The surgical technique follows the principles described beforehand Preoperative planning for correct stent placement is important Then the stents are expanded and height is restored Afterwards, the cementing is performed in exactly the same manner as in a vertebroplasty procedure, taking the same precautions To obtain sufficient support, determining the appropriate amount of cement is crucial The cement should infiltrate the surrounding bone (Fig 3.6-7, Fig 3.6-8) Cement injection Low-viscosity cement should not be injected Another consideration is that many injection tools on the market are not well designed, and should not be used as they not allow the injection of high-viscosity cement The use of small syringes (1 cc, cc) or the plunger technique, which is applied in kyphoplasty, allows direct feedback during cement injection and provides the best way of injecting high-viscosity cement • Prepare the cement and inject it once it has reached the desired viscosity • Carry out cement injection under continuous lateral C-arm control with intermittent AP checks (Fig 3.6-6) • Stop injecting whenever any cement leakage is observed—depending on the type of cement used, injection can be resumed after 45 to 180 seconds (check the clock) • Complete the filling procedure until the vertebral body is supported from the upper to the lower endplate respectively to the stable area of the VB • Wait until the cement has set, then remove cannula and close the stab incision • Parallel injection of up to three levels/cannulas can be performed if the surgeon is experienced Ensure that there is sufficient cement available when treating the lumbar spine • The maximum amount of cement that can be injected safely in one session is about 25 cc [10] • Any manipulation or injection in the VB displaces fat into the venous system, regardless of which technique is used 6.4 Height restoration by stentoplasty Vertebral body compression fractures usually increase the kyphotic deformity, thereby altering the spinal balance with an increasing load on the anterior column and higher strain on the back muscles In severely deformed vertebral bodies that still show a potential for height restoration (see topic in this chapter) the use of a vertebral body stent is recommended Adopting this approach should be considered if the kyphosis is more than 15° or the vertebral body shows 248 AOS_MISS_Book.indb 248 a b c d e f g Fig 3.6-7a–g a–b Preoperative CT scan for the planning of stent placement in a 78-year-old man that presented with a 4-week history of severe back pain c–e Intraoperative view before and after stent expansion with subsequent height restoration f–g Standing postoperative view showing maintained alignment, with prophylactic cement injection of the adjacent levels The fact that the patient had a history of steroid medication and a smokingassociated obstructive pulmonary disorder represents a high risk for adjacent fractures Therefore the prophylactic injection of the adjacent levels appears justified Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies  Roger Härtl, Andreas Korge 10/30/12 11:12 AM 3  Thoracic techniques 3.6  Vertebroplasty and percutaneous cement reinforcement techniques * * a b c d Fig 3.6-8a–f a Supine view showing a mild compression fracture at L1 and T12 in a 77-year-old man (asterix) b MRI showing a signal change at L1, indicating a fresh lesion, whereas the signal at T12 is regular c Preoperative standing view showing an important height loss and displacement of the anterior wall (arrows) d Expanded titanium vertebral body stent e–f Complete height gain of the fractured vertebra can be seen following stentoplasty e f 249 AOS_MISS_Book.indb 249 10/30/12 11:12 AM Authors  Paul Heini, Mark Kleinschmidt 6.5 Cement reinforcement for enhanced implant anchorage / Avoidance of fractures adjacent to a stabilization The problems related to osteoporosis and internal fixation are increasing, as well as the numbers of patients with VCFs and concomitant neurological involvement, or patients with spinal instabilities and spinal stenosis In these cases, additional stabilization is necessary but fixation failure remains a major issue Furthermore, vertebral fractures adjacent to the stabilization are a common problem The application of PMMA to increase spinal stability has been used for a long time Vertebroplasty offers the option of using the same fixation principles as those for normal bone To increase the stability of the screws, a vertebroplasty procedure is performed in which the pedicle screws a d 250 AOS_MISS_Book.indb 250 b e are inserted before the cement has set This technique allows the use of any standard stabilization system The procedure is somewhat complex and time-consuming, but reliable Alternatively, perforated screws allow direct cement injection through the screw, thus improving stability (Fig 3.6-9) The amount of cement required for improving stability is between and cc per screw Certain cements are available with a very long duration of effectiveness that allow safe cement injection through four screws in one run The same principles and precautions apply as for any other cement injection technique Today, the clear indication for additional cement reinforcement remains an open question If maximizing the implant dimensions (diameter, length) appears insufficient, the surgeon should consider enhancing the fixation stability using cement c Fig 3.6-9a–e  Screw reinforcement techniques A vertebroplasty procedure directly followed by screw insertion allow the adoption of standard techniques for implants, as in healthy bone Perforated screws permit direct cement injection For any of these techniques the principle of vertebroplasty applies and needs careful C-arm monitoring Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies  Roger Härtl, Andreas Korge 10/30/12 11:12 AM 3  Thoracic techniques 3.6  Vertebroplasty and percutaneous cement reinforcement techniques To decrease the incidence of VCFs subsequent to fixation, prophylactic reinforcement of the vertebrae next to the fixation level can be carried out The risk of a fatigue fracture following stabilization increases with the number of levels fixed Therefore, special attention is required for dealing with scoliosis correction in the elderly Common failures include fractures of the adjacent vertebrae and failure of the last instrumented vertebrae Failure may occur despite cemented screw fixation and the prophylactic augmentation b a c of the adjacent levels Adjacent level injections can be performed during the main intervention, if the patient can tolerate the additional cement In this case, the main procedure is carried out and the percutaneous injection is performed under the same anesthesia Alternatively, the patient can be treated secondarily under local anesthesia during the early postoperative phase, after 1–3 weeks Adjacent fractures are usually observed very early on, within the first weeks (Fig 3.6-10) d e Fig 3.6-10a–e  Failure pattern in the adjacent vertebrae In long constructs, an adjacent fracture can occur despite the “good” hold of implants Even with the prophylactic cementing of adjacent levels, the bone can give way and the disc space collapse 251 AOS_MISS_Book.indb 251 10/30/12 11:12 AM Authors  Paul Heini, Mark Kleinschmidt 6.6 Anterior column support by PMMA injection A further aspect to be considered in the context of vertebroplasty is the issue of anterior column support in deficient spines, ie, spines with severe osteoporotic fractures or tumors Once posterior fixation has been completed, it may be found that stabilization/support of the anterior column is necessary Instead of carrying out another intervention to reinforce the anterior column an additional cementing procedure can be performed, in which high-viscosity cement is used to fill the void/defect As the segment is stabilized and intended to fuse, the cement is also applied into the disc space without hesitation Usually very high amounts of cement are required to achieve sufficient stability This is a technically demanding intervention, in which the surgeon should use biplanar imaging Filling should be aggressive, in order to prevent the risk of the cement plug loosening, with accompanying instability that could provoke further erosion and failure to the construct (Fig 3.6-11) a Postoperative care After a percutaneous cementing procedure (vertebroplasty, kyphoplasty, stentoplasty) the patient is placed supine for hour to apply compression to the back muscles During the operation, a painful hematoma may develop shortly after the injection After the surgical procedure, the patient can be mobilized as much and as early as tolerated whether they undergo a general or local anesthesia Sutures are removed after week The patient should avoid forced forward bending during the early postoperative phase; otherwise, there are no restrictions except for heavy lifting No brace is applied Patients should be instructed about the risk of further fractures, and reexamined whenever new pain occurs The osteopath or family doctor should provide systematic treatment for the osteoporosis according to the established guidelines b d f c e g Fig 3.6-11a–g  L3 fracture in a 72-year-old woman Obvious instability can be seen on comparing standing and supine views (arrows) After decompression and stabilization, an increased defect of the anterior column became apparent Percutaneous cement injection (about 20 cc of cement) was performed under biplanar C-arm monitoring The filling pattern corresponds to the preoperative CT scan 252 AOS_MISS_Book.indb 252 Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies  Roger Härtl, Andreas Korge 10/30/12 11:12 AM 3  Thoracic techniques 3.6  Vertebroplasty and percutaneous cement reinforcement techniques Evidence-based results As mentioned at the onset, vertebroplasty has gained widespread acceptance for treating VCFs and metastatic lesions Numerous case series have been published, which report favorable outcomes in about 80–90% of patients, with significant pain reduction immediately after the intervention and a good mid-term outcome [5] Two RCTs comparing vertebroplasty against a sham procedure, however, have questioned the efficacy of this intervention [8] In these trials, the patients showed a modest but similar improvement, regardless of whether a facet-joint infiltration or a real cement injection had been used Although the presented results were based on sound statistical analysis, the findings are disputable as their external validity has not been established: patients with older fractures had been chosen, and the technical aspects were ignored [11] On the other hand, a recent RCT (VERTOS II) comparing vertebroplasty against conservative treatment shows that the former procedure is advantageous and also demonstrates its costeffectiveness [4] Finally, a survey assessing the 4-year survival probability in a US Medicare population including more than 800,000 patients with a diagnosis of VCF shows a strong and highly statistical difference in favor of vertebroplasty and kyphoplasty [12] Complications and avoidance The risks and complications related to any cement reinforcement procedure can be seen in the surgical steps involved Misplacement of the cannulas can injure a nerve root or even the spinal cord Vascular injury may also occur, with anterior perforation of the vertebrae However, if the surgical principles and the anatomical landmarks are respected, can- 10 nula placement appears to be a safe procedure Using a guidewire allows for easy navigation and change of orientation and is additionally helpful if large-diameter cannulas are used The foremost problem and major risk is that regarding cement leakage Although most cement leaks are clinically not relevant, cement embolism with a lethal outcome as well as cement leakage into the canal with subsequent spinal cord compression and paraplegia have been reported [13] Avoiding this complication primarily means being aware of the potential risks and understanding the basic principles of injection biomechanics and rheology The most important factor in leakage is cement viscosity Only high-viscosity cement should be used for the procedure Therefore, cementing systems with long delivery tubes are not appropriate Only large cannulas (8-, 10-gauge) should be used The safest and simplest means of cement injection is to use small syringes or a plunger system that also allow the injection of very pasty cements Cement behavior and duration of working time are important aspects If any leakage is observed, the injection must be stopped immediately After waiting 1–3 minutes (depending on individual cement characteristics) the injection can be continued The cement sets faster at body temperature, which can help in occluding local openings, and then the filling can be completed as desired Sometimes the above steps, ie, trying then waiting, need to be repeated If the leakage cannot be controlled, the injection must be stopped The risk of adjacent fractures presents a further problem In severely osteoporotic patients, injecting the adjacent levels in a prophylactic manner seems justified [14] Based on the individual risk profile and the patient's specific anatomical characteristics, the surgeon should consider the injection of cement at multiple levels Tips and tricks Bronek Boszczyk, Nottingham, UK ance of bone marrow displacement into • Typically individual stages are 4–6 weeks • Increasing prevalence of adult defor- the bloodstream (excessive amounts can apart, but can be shorter if well tolerated mity, corrective implant constructs uti- cause acute pulmonary hypertension and As stated by the authors this is possible lizing PMMA to supplement purchase in the worst case heart failure) with any pedicle screw system, whereby • In a staged procedure, PMMA-augmented the use of “anterior” spinal screws with a screws can be placed in one or two sepa- deeper thread probably provide the high- • These frequently complex reconstructive rate procedures with a final subsequent est resistance to pullout if required procedures occasionally benefit from a procedure to complete the construct with staged procedure due to the limited toler- rod insertion and the frequently neces- in osteopenic or osteoporotic bone are becoming more common sary osteotomies 253 AOS_MISS_Book.indb 253 10/30/12 11:12 AM Authors  Paul Heini, Mark Kleinschmidt 11 Case examples 11.1 Case shows a straightforward case example: a 77-yearold man fell from a ladder, and was admitted to the hospital The supine films showed a mild compression fracture at L1 and T12 (Fig 3.6-8a; asterix) MRI showed a signal change at L1 that indicated a fresh lesion, whereas the signal at T12 was regular (Fig 3.6-8b) The decision regarding whether to perform conservative or surgical treatment was based on a standing film taken on the day of admission The film showed an important height loss with displacement of the anterior wall (Fig 3.6-8c; arrows) Therefore, a percutaneous height restoration procedure (stentoplasty) was perFig 3.6-8 a b formed, with complete height gain of the fractured vertebra (Fig 3.6-8d–f) This case illustrates the utility of MRI assessment when multiple fractures are present, and of comparing standing and supine images to determine the stability 11.2 Case An 81-year-old woman presented with a 1-year history of mild spinal claudication, and now with acute immobilizing back pain and increased leg pain when standing (Fig 3.6-12) MRI showed a fresh mild compression fracture at L2 A vertebroplasty procedure was performed to stabilize the vertebral body The aim of treatment was primarily pain control and the prevention of further collapse to avoid the progression of stenosis c d Fig 3.6-12a–d a–b Preoperative MRI showing a fresh mild compression fracture at L2 in an 81-year-old woman c–d A vertebroplasty procedure was performed to stabilize the vertebral body 254 AOS_MISS_Book.indb 254 Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies  Roger Härtl, Andreas Korge 10/30/12 11:12 AM 3  Thoracic techniques 3.6  Vertebroplasty and percutaneous cement reinforcement techniques 12 Key learning points • VCFs are the hallmark of osteoporosis, the incidence of which increases exponentially with advancing age • Cement reinforcement appears to be an efficient means of stabilizing painful fragility fractures caused by osteoporosis or metastatic lesions • Indications for treatment should focus on patients with acute fractures with progressive collapse and/or patients who are bedridden due to a fracture 13 • Subacute fractures with positive MR scan and especially with persisting mobility in the fracture show a favorable response to treatment by vertebroplasty • The inherent risk in any percutaneous cement injection procedure is that of cement leakage Cement viscosity is the determining factor in this risk • Patients with osteoporotic VCFs should undergo osteological work-up and receive osteoporosis treatment References Galibert P, Deramond H, Rosat P, et al (1987) [Preliminary note on the treatment of vertebral angioma by percutaneous acrylic vertebroplasty.] Neurochirurgie; 33(2):166–168 German Heini PF, Pfäffli S (2009) [Cement injection for spinal metastases (vertebroplasty and kyphoplasty).] Orthopade; 38(4):335–336, 338–342 German Jensen ME, Evans AJ, Mathis JM, et al (1997) Percutaneous polymethylmethacrylate vertebroplasty in the treatment of osteoporotic vertebral body compression fractures: technical aspects Am J Neuroradiol;18(10):1897–1904 Klazen CA, Lohle PN, de Vries J, et al (2010) Vertebroplasty versus conservative treatment in acute osteoporotic vertebral compression fractures (VERTOS II): an open-label randomised trial Lancet; 376(9746):1085-1092 Muijs SP, Nieuwenhuijse MJ, Van Erkel AR, et al (2009) Percutaneous vertebroplasty for the treatment of osteoporotic vertebral compression fractures: evaluation after 36 months J Bone Joint Surg Br; 91(3):379–384 Berlemann U, Franz T, Orler R, et al (2004) Kyphoplasty for treatment of osteoporotic vertebral fractures: a prospective non-randomized study Eur Spine J; 13(6):496–501 Hulme PA, Krebs J, Ferguson SJ, et al (2006) Vertebroplasty and kyphoplasty: a systematic review of 69 clinical studies Spine; 31(17):1983–2001 Kallmes DF, Comstock BA, Heagerty PJ, et al (2009) A randomized trial of vertebroplasty for osteoporotic spinal fractures N Engl J Med; 361(6):569–579 Baroud G, Crookshank M, Bohner M (2006) High-viscosity cement significantly enhances uniformity of cement filling in vertebroplasty: an experimental model and study on cement leakage Spine; 31(22):2562– 2568 10 Diel P, Freiburghaus L, Röder C, et al (2011) Safety, effectiveness and predictors for early reoperation in therapeutic and prophylactic vertebroplasty: short-term results of a prospective case series of patients with osteoporotic vertebral fractures Eur Spine J; 21 Suppl 6:S792–S799 11 Boszczyk B (2010) Volume matters: a review of procedural details of two randomised controlled vertebroplasty trials of 2009 Eur Spine J; 19(11):1837– 1840 12 Edidin AA, Ong KL, Lau E, et al (2011) Mortality risk for operated and nonoperated vertebral fracture patients in the Medicare population J Bone Miner Res; 26(7):1617–1626 13 Baumann C, Fuchs H, Kiwit J, et al (2007) Complications in percutaneous vertebroplasty associated with puncture or cement leakage Cardiovasc Intervent Radiol; 30(2):161–168 14 Diel P, Merky D, Röder C, et al (2009) Safety and efficacy of vertebroplasty: early results of a prospective one-year case series of osteoporosis patients in an academic high-volume center Ind J Orthop; 43(3):228–233 255 AOS_MISS_Book.indb 255 10/30/12 11:12 AM Authors  Paul Heini, Mark Kleinschmidt 14 Evidence-based summaries Baroud G, Crookshank M, Bohner M (2006) Highviscosity cement significantly enhances uniformity of cement filling in vertebroplasty: an experimental model and study on cement leakage Spine; 31(22):2562–2568 Study type Laboratory testing Study design Experimental study Class of evidence N/A Purpose To examine the working hypothesis that high-viscosity cements will spread uniformly, thus significantly reducing the risk of leakage Kallmes DF, Comstock BA, Heagerty PJ et al (2009) A randomized trial of vertebroplasty for osteoporotic spinal fractures N Engl J Med; 361(6):569–579 Study type Therapy Study design Randomized controlled trial Class of evidence I–II Purpose To compare the outcomes of patients with one to three painful osteoporotic vertebral compression fractures randomized to undergo either vertebroplasty or a simulated procedure without cement P Patient N/A (experimental model of the leakage phenomenon of vertebroplasty) P Patient Painful osteoporotic vertebral compression fractures (N = 131) I Intervention Injection of cement of varying viscosities I Intervention Vertebroplasty (n = 68) C Comparison No comparison group C Comparison O Outcome Filling pattern, cement mass that has leaked, time at which leakage occurred, injection pressure Simulated procedure without cement (control group; n = 63) O Outcome Modified Roland-Morris Disability Questionnaire (RDQ), patients' ratings of average pain intensity, adverse events Authors’ conclusion High-viscosity cement seems to stabilize cement flow However, the forces required for the delivery of highviscosity cement may approach or exceed the human physical limit of injection forces and may not be manually injectable with a standard syringe or cannula 256 AOS_MISS_Book.indb 256 Authors’ conclusion Improvements in pain and pain-related disability associated with osteoporotic compression fractures in patients treated with vertebroplasty were similar to the improvements in a control group Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies  Roger Härtl, Andreas Korge 10/30/12 11:12 AM 3  Thoracic techniques 3.6  Vertebroplasty and percutaneous cement reinforcement techniques Klazen CA, Lohle PN, de Vries J et al (2010) Vertebroplasty versus conservative treatment in acute osteoporotic vertebral compression fractures (Vertos II): an open-label randomized trial Lancet; 376(9746):1085– 1092 Study type Therapy Study design Randomized controlled trial Class of evidence I–II Purpose To clarify whether vertebroplasty has additional value compared with conservative treatment in patients with acute osteoporotic vertebral compression fractures Diel P, Freiburghaus L, Röder C, et al (2011) Safety, effectiveness and predictors for early reoperation in therapeutic and prophylactic vertebroplasty: short-term results of a prospective case series of patients with osteoporotic vertebral fractures Eur Spine J; [Epub ahead of print] Study type Therapy Study design Case series Class of evidence IV Purpose To assess the safety and efficacy of vertebroplasty in alleviating pain, improving quality of life, and restoring alignment P Patient Patients with osteoporotic vertebral compression fractures (N = 202) P Patient Patients with osteoporotic vertebral fractures (N = 233) I Intervention Percutaneous vertebroplasty (n = 101) I Intervention Vertebroplasty (n = 249 interventions) C Comparison Conservative treatment (n = 101) C Comparison No comparison group O Outcome Pain measures by VAS score O Outcome Demographics, treatment and x-ray details, pain alleviation (VAS), QoL Improvement (NASS and EQ-5D), complications, and predictors for new fractures requiring reoperation Authors’ conclusion In a subgroup of patients with acute osteoporotic vertebral compression fractures and persistent pain, percutaneous vertebroplasty is effective and safe Pain relief after vertebroplasty is immediate, is sustained for at least one year, and is significantly greater than that achieved with conservative treatment, at an acceptable cost Authors’ conclusion If routinely used, vertebroplasty is a safe and efficacious treatment option for osteoporotic vertebral fractures with regard to pain relief and improvement in the quality of life Even segmental realignment can be partially achieved with proper patient positioning 257 AOS_MISS_Book.indb 257 10/30/12 11:12 AM Authors  Paul Heini, Mark Kleinschmidt Edidin AA, Ong KL, Lau E, et al (2011) Mortality risk for operated and nonoperated vertebral fracture patients in the Medicare population J Bone Miner Res; 26(7):1617–1626 Study type Therapy Study design Case series Class of evidence IV Purpose To evaluate the mortality risk for patients with vertebral compression fractures (VCFs) undergoing nonoperative (conservative) and operative (kyphoplasty or vertebroplasty) treatment P Patient VCF (N = 858,978) I Intervention Operative treatment (n = 182,946: n = 119,253 kyphoplasty, n = 63,693 vertebroplasty) C Comparison Nonoperative treatment (n = 676,032) O Outcome Mortality rate Authors’ conclusion The authors observed improved survivorship for patients after treatment of VCF in the operated group compared to the nonoperated group, and also detected a significantly improved survival rate for patients treated with kyphoplasty compared with vertebroplasty 258 AOS_MISS_Book.indb 258 Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies  Roger Härtl, Andreas Korge 10/30/12 11:12 AM 3  Thoracic techniques 3.6  Vertebroplasty and percutaneous cement reinforcement techniques 259 AOS_MISS_Book.indb 259 10/30/12 11:12 AM Author  Roger Härtl 260 AOS_MISS_Book.indb 260 Minimally Invasive Spine Surgery—Techniques, Evidence, and Controversies  Roger Härtl, Andreas Korge 10/30/12 11:12 AM ...AOS_MISS_Book.indb 10 /30 /12 11 :08 AM Roger Härtl  |  Andreas Korge Minimally Invasive Spine Surgery Techniques, Evidence, and Controversies AOS_MISS_Book.indb 10 /30 /12 11 :08 AM AOS_MISS_Book.indb 10 /30 /12 11 :08... 17 10 /30 /12 11 :08 AM Author  Andreas Korge XVIII AOS_MISS_Book.indb 18 Minimally Invasive Spine Surgery Techniques, Evidence, and Controversies  Roger Härtl, Andreas Korge 10 /30 /12 11 :08 AM 1 ... screw fixation 13 5 2.5 Anterior C1/2 surgery 15 1 spine surgery 1. 7 Biologics in minimally invasive spine surgery 85 1. 8 Anesthetic considerations and minimally invasive  91 spine surgery XIV