Vertebral Columns Fall 2016

Vertebral Columns

ISA

SS

International Society for the Advancement of Spine Surgery

Fall 2016

Boca Raton Resort & Club, Home of ISASS17

In This Issue EDITOR’S PERSPECTIVE Ethical Implications of Learning Curves in Minimally Invasive Surgery...................................................................................................4 POLICY The Cost of Denial................................................................................. 7 NEW TECHNOLOGY Minimally Invasive Midline Fusion: LinkSpine......................................9 POINT-COUNTERPOINT The Direct-Look LLIF Technique: A Natural Evolution of a Minimally Invasive Surgery....................................................................................11 POINT-COUNTERPOINT Graft Biomaterials................................................................................ 13 NEW TECHNOLOGY Multimodal Analagesia (MMA) in Spine Surgery: A New Way Forward ............................................................................................................. 15 PAIN CONTROL Liposomal Bupivacaine For Post-Operative Pain Control In MIS Spine Procedures............................................................................................ 19 COMPLICATIONS When can anti-platelet therapy be stopped after cardiac stenting?....... 21 2

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Editor in Chief Kern Singh Editorial Board Matthew Colman, MD Jeffrey Goldstein, MD Jonathan Grauer, MD Hamid Hassanzadeh, MD Safdar Khan, MD Choll Kim, MD, PhD Mark Kurd, MD Yu-Po Lee, MD Vikas Mehta, MD Isaac Moss, MD John O’Toole, MD Alpesh Patel, MD Sheeraz Quereshi, MD Kris Siemionow, MD Seth Williams, MD Publisher Jonny Dover Vertebral Columns is published quarterly by the International Society for the Advancement of Spine Surgery. © 2016 ISASS. All rights reserved.

Opinions of authors and editors do not necessarily reflect positions taken by the Society.

This publication is available digitally at https://vertebralcolumns.com.

ISSN 2414-6277.

REDEFINING

LATERAL adjective | LAT•TER•AL | /’ladərəl/ 1. Minimally invasive surgery with improved visualization, access, and distraction.

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Vertebral Columns • Summer/Fall 2016

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EDITOR’S PERSPECTIVE

Ethical Implications of Learning Curves in Minimally Invasive Surgery Ankur S. Narain, BA1 Fady Y. Hijji, BS1 Kelly H. Yom, BA1 Krishna T. Kudaravalli, BS1 Kern Singh, MD1 Department of Orthopaedic Surgery, Rush University Medical Center, 1611 W. Harrison St. Suite #300, Chicago, IL, 60612 1

Disclosure: No funds were received in support of this work. No benefits in any form have been or will be received from any commercial party related directly or indirectly to the subject of this manuscript.

Introduction Surgical innovation is a crucial aspect in the advancement of medical practice. However, in order to utilize these surgical innovations, a learning curve is necessary. Learning curves represent the notion that proficiency at a particular task increases with experience. White et al. described the learning curve as encompassing three phases1.

In the initial learning phase, the practitioner has the lowest success ratio and highest complication rate.

In the consolidation phase, failure and complication rates decrease as experience is gained. Finally, in the plateau phase, the practitioner attains procedural expertise with the highest possible success ratio.

Learning curves are especially relevant to those practicing minimally invasive surgery (MIS), with 4

multiple studies performed in the orthopedic spine and general surgical literature. Furthermore, learning curves and their application to surgical practice have raised significant ethical concerns. The purpose of this commentary is to investigate the ethics of learning curves in minimally invasive surgery, while also using relevant examples from other industries to suggest possible solutions to ethical dilemmas.

Learning Curves In Minimally Invasive Procedures Learning curves have been described within the orthopedic spine literature, suggesting that surgical cases performed earlier in a surgeon’s career have differences in perioperative outcomes when compared to later cases. Ahn et al., in a study of 228 consecutive patients undergoing MIS lumbar decompression (MIS LD), demonstrated that the first 50 cases had significantly longer operative times and length of inpatient stay than the subsequent 178 cases2. Wang et al. demonstrated similar findings, while also noting increased complication rates and necessity for conversion to open procedures in the earlier patient cohort3. In a study examining patients undergoing lumbar fusion via MIS transforaminal lumbar interbody fusion (TLIF), Nandyala et al. demonstrated that earlier cases were associated with increased operative times, intraoperative blood loss,

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administration of intraoperative fluids, and duration of anesthesia4.

Lee et al. further demonstrated that earlier cohorts undergoing MIS TLIF exhibited increased fluoroscopy exposure times, increased duration of patient-controlled analgesia, and increased rate of complications compared to later cohorts5.

These findings regarding learning curves also extend to other surgical fields utilizing minimally invasive techniques. For example, in a study investigating the learning curve of a single surgeon performing robotic colectomy, Foo et al. demonstrated that operative time and complication rates were higher in the first 25 cases versus the final 14 cases6.

Similar trends were also seen in practitioners performing laparoscopic hysterectomies, with earlier cohorts demonstrating increases in operative time, hemorrhage, complications, and conversion rates compared to later cases7,8.

Ethical Considerations The primary ethical dilemma in the adoption of innovative surgical procedures is reconciling the need to gain operative experience with the need to prevent unnecessary patient harm1,9-13. As illustrated by the previously mentioned studies, patients treated at the beginning of a surgeon’s learning curve are subjected to risks that are reduced or not present as the surgeon gains experience. However, surgeons must gain experience on actual

patients in order to reach the level of proficiency required to provide the intended benefits of the procedure for future patients. Multiple opinions regarding this dilemma have been given. White et al. argues that surgical learning curves are ethically justified because the procedure itself is beneficent1.

The authors derive beneficence from the notion that the primary goal of the procedure is to alleviate the patient’s symptoms, with the secondary benefit being improving procedural proficiency for the surgeon. Ives et al. further justifies surgical learning curves by suggesting that early cohorts of patients receive long-term benefits, as they have aided in the training of experienced physicians whose services they may utilize in the future11. Regardless of whether learning curves are ethically justified, they are a required aspect of medical practice and measures must be taken to prevent patient harm during the initial learning phases.

In developing strategies for reducing patient harm in MIS, many lessons can be drawn from the aviation industry14-16. Like medicine, aviation involves learning and utilizing technically difficult skills to operate expensive equipment in high-stakes, high-stress environments. Training principles in aviation, however, are different. First, aviation utilizes a “type-rating” system which encompasses many hours of situation and aircraft specific training modules16. Outside of short technical classes, there is no such equivalent for physicians looking to learn a new surgical technique. Second, the use of simulators is much more extensive in aviation, with initial proficiency testing and recertification exam-

inations having significant simulation components14-16. While the use of simulation is increasing in the medical field, in very few cases is a surgeon required to show simulation proficiency before they are allowed to perform a newly learned procedure. Finally, aviation training requires significant proctored flight time before certification is awarded16. There is no analogous requirement for surgeons to be proctored by an expert before incorporating a new procedure into their practice.

Using ideas from the aviation industry and the medical ethics literature, recommendations can be made regarding risk mitigation during the early stages of the MIS learning curve9-16. Before performing any new procedure on a patient, more complete scrutiny of the research regarding new procedures should occur9,13. Furthermore, surgeons should undergo more extensive training in the new procedure, including didactic sessions, cadaver sessions, and simulations9,12-16. Ideally, proficiency during a simulation should be required before one can progress to procedures involving patients.

When initially implementing new procedures into their practice, surgeons should also consider a preceptorship in which they are supervised for a number of cases by an expert. This preceptorship may help to prevent common pitfalls and complications at the beginning of the learning curve.

Finally, surgeons should embrace more complete reporting of errors when complications do arise9,14,15.

By doing so, not only are physicians encouraged to examine and correct their own mistakes, but they also provide their colleagues with the information necessary to

avoid those mistakes in their own practice.

Conclusions When learning new surgical techniques, an ethical dilemma arises in trying to gain operative experience while also preventing excess risk to the patient. While risks associated with the learning curve for new procedures cannot completely be avoided, preventative measures can be taken. Surgeons should ensure they are adequately prepared to perform novel procedures through thorough preparation in terms of didactic instruction and simulations. The use of expert preceptors to guide initial cases may also help to prevent unnecessary harm.

References 1. White SM. The ethics of anaesthesia learning curves. Anaesth Intensive Care 2009;37:824-9.

2. Ahn J, Iqbal A, Manning BT, et al. Minimally invasive lumbar decompression-the surgical learning curve. Spine J 2016;16:909-16.

3. Wang B, Lu G, Patel AA, et al.

An evaluation of the learning curve for a complex surgical technique: the full endoscopic interlaminar approach for lumbar disc herniations.

Spine J 2011;11:122-30.

4. Nandyala SV, Fineberg SJ, Pelton M, et al. Minimally invasive transforaminal lumbar interbody fusion: one surgeon’s learning curve. Spine J 2014;14:1460-5.

5. Lee KH, Yeo W, Soeharno H, et al. Learning curve of a complex surgical technique: minimally invasive transforaminal lumbar interbody fusion (MIS TLIF). J Spinal Disord Tech 2014;27:E234-40.

6. Foo CC, Law WL. The Learning Curve of Robotic-Assisted Low Rectal Resection of a Novice Rectal Surgeon. World J Surg 2016;40:456-62.

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7. Voitk AJ, Tsao SG, Ignatius S. The tail of the learning curve for laparoscopic cholecystectomy. Am J Surg 2001;182:250-3.

8. Wattiez A, Soriano D, Cohen SB, et al. The learning curve of total laparoscopic hysterectomy: comparative analysis of 1647 cases. J Am Assoc Gynecol Laparosc 2002;9:339-45.

9. Gates EA. New surgical procedures: can our patients benefit while we learn? Am J Obstet Gynecol 1997;176:1293-8; discussion 8-9.

10. Healey P, Samanta J. When does the ‘learning curve’ of innovative interventions become question-

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able practice? Eur J Vasc Endovasc Surg 2008;36:253-7.

11. Ives J. Kant, curves and medical learning practice: a reply to Le Morvan and Stock. J Med Ethics 2007;33:119-22.

12. Le Morvan P, Stock B. Medical learning curves and the Kantian ideal. J Med Ethics 2005;31:513-8.

13. Morgenstern L. Warning! Dangerous curve ahead: the learning curve. Surg Innov 2005;12:101-3.

14. Kao LS, Thomas EJ. Navigating towards improved surgical safety using aviation-based strategies. J Surg Res 2008;145:327-35.

15. Singh N. On a wing and a

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prayer: surgeons learning from the aviation industry. J R Soc Med 2009;102:360-4.

16. Sommer KJ. Pilot training: What can surgeons learn from it?

Arab J Urol 2014;12:32-5.

Correspondence Kern Singh, MD Associate Professor Department of Orthopaedic Surgery Rush University Medical Center 1611 W. Harrison St, Suite #300 Chicago, IL 60612 E-mail: kern.singh@rushortho.com

POLICY

The Cost of Denial Morgan Lorio Denial is on a basic level denying that which one held as a tenet of truth to be otherwise; within the realm of healthcare, it is the decision by an insurer (private or government) to not provide a desired remedy that might very well impact that person’s right to life and subsequently the pursuit of happiness.

On a most limbic, heart-felt primitive level, it is stealing. Health Insurance implies that health and well being are insured (covered) by a price that is paid completing a transaction; the insured, unfortunately, does not understand that it is a business and that the outcome will be calculated as to benefit the guarantor first and foremost, even at the cost of the life of the ‘benefited.’ Philosophically, denial is an erudite veil to cover the gain of a few over the loss of many.

In a ‘value-based’ health system as compared to fee-for-service, health systems are rewarded for limiting services (denial) and the provider is penalized for providing that service in an imperfect world. Specialists are accused of failing the system in that the threshold of providing more expertise for less is invariably reached; that is to say, the provider can ill afford to pay for his privilege to apply his art. Similarly, investments in emerging technology which bear promise are rewarded with less, leading to a stagnation of medical industry advancements.

Society is not sympathetic to Doctors (MDs and DOs) or to Industry as the prevailing sentiment is that other Health Care Team Providers with either PhDs or MBAs will manage this crisis thru ‘value-based’ performance measures.

Generalized apathy has become a conditioned, politically correct Applying standards derived from defense mechanism of coping with English Law, the cost of denial, is denial to resist further erosion of therefore the failure to provide the the status quo. This cost of denial value of the cost in any event (from is increasingly experienced in the a patient or their physician’s perspine world. Spinal health is not a spective). For the sake of argument, subject of sexy entertainment; nor the costs of denial are caught up in does it command voter turnout. costs in the case (review, appeal, Spinal health is not life giving nor etc), costs thrown away, costs of is it necessarily life saving. Spinal and costs by other parties, and most health is life prolonging and is thus importantly, no order as to costs. It a subject of manipulated public disis the latter cost which comprises dain as coverage requires the input the focus of this article, that is to of costly services and technology. say the insured personally bears uncovered economic, social, and The real-life cost of denial is health costs or these same costs are anecdotally embodied in the tale shifted either thru private insurance of one of my own spine surgery change or back to government. successes and failures in retrospect. This real-life patient gave

me permission to relate his cost of denial, indeed he asked that tell his tale. My adolescent patient was 19 years of age when I first met him with long-standing, debilitating back and radicular pain secondary to a severely degenerated L5/S1 para-central disc herniation superimposed on a Grade 1-plus Spondylolisthesis with an extreme, abnormal sacral-inclination angle. He failed conservative treatment and required a peer review with appeal to be approved for an extended, two-level, instrumented, combined interbody and posterior fusion with iliac autograft and wide decompression.

After surgery, my patient stated that he was, “beyond better, never felt so good.” He received an external bone stimulator and LSO brace as adjuncts to his spine care.

Approximately six month post operatively, his pain returned. This subjective report of pain recurrence was initially attributed to deconditioning and post-laminectomy syndrome. However, a subsequent CT demonstrated resorption of posterior and interbody fusion mass and sagittal toggling of his sacral fixation of greater than seven millimeters objectively heralding a symptomatic non-union or pseudoarthrosis. A combined Vitamin D and Testosterone deficiency have since been indentified as contributing etiologies for this surgical failure; these deficiencies are under medical treatment now.

My patient describes his situation as a ‘mixed recovery.’

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His costs of denial began with his costs awaiting insurer coverage approval for his index procedure.

In that fusion recovery takes ‘a while,’ there are inherent additional costs. My patient is not currently able to do plant work for gainful employment any longer and thus applied for short term disability as he awaits insurer coverage approval for revision which has been denied in that he is just shy of one year from his index surgical intervention and his pseudoarthrosis involves two levels.

My patient can only now obtain pain relief with narcotics for which he suffers ‘motion sickness.’ His

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abhorrence of narcotics in general as well as their side-effects results, therefore, in no abilities. My patient relates that he can not sleep, hunt, lift or exercise, or work gainfully. Meanwhile, he has been told by short-term disability that he can work at a fast food chain without a doctor’s release. He was furthermore sent for psychological and social work assessments and advised that his intelligence level was sufficient for him to be a Walmart greeter.

My patient is now a 21 year old young man. If one simply looks at him, he appears to be fit and healthy. If one asks him how he

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is doing, he will answer that he is, “in pain all the time and depressed.” He goes on to state that, “denial is the biggest hindrance of my life.” He additionally adds that, “it is sad for a person to look forward to a revision surgery.” We (I and my patient) are still awaiting the appeal process as we are technically past the one year period of establishing the presence of his pseudoarthrosis if the examiner accepts my radiographic review in that the outside radiology report makes no comment on the fusion status or subtle sagittal hardware motion. My patient has a long life to live.

NEW TECHNOLOGY

Minimally Invasive Midline Fusion: LinkSpine Mark F. Kurd MD, Chris D. Chaput, MD, and Dennis Farrell There is continued interest in less invasive techniques for spinal stabilization. Implants that can be placed through small midline approaches are attractive because they do not require the surgeon to learn different nonstandard decompression techniques or off-midline approaches. Lumbar transfacet screw fixation is one technique that lends itself to less invasive exposures. It was first described by King in 19481, who directed the screw through the inferior facet of the cephalad vertebra to be fused, and angled it downward and outward through the articulating facet joint. Eleven years later, Boucher et al modified the technique to help achieve fusion with the use of longer screws that are aimed across the facet joints, terminating at the base of the pedicle2. Unlike conventional pedicle screws and rods (PSR), transfacet pedicle screws (TFPS) do not span the three columns of the vertebrae.

However, when TFPS are compared to PSR in conjunction with interbody spacers, several authors have demonstrated similar biomechanical performance3,4,5. These reports conclude that TFPS and bilateral PSR have similar rigidity in flexion and extension, however PSR show greater stability in axial rotation and lateral bending.

Overall, these studies suggest that transfacet fixation is comparable to pedicle screw fixation when used in

Figure 1. FacetLINK Mini.

Figure 4. Post-operative oblique view.

Figure 2. Post-operative AP view.

Figure 3. Post-operative lateral view.

conjunction with interbody support. PSR remain biomechanically superior when used in isolation.

The FacetLINK MINI (Fig. 1) is an innovative midline fusion device designed to minimize the amount of muscle stripping and tissue dissection that is required for placement of a posterior lumbar fusion construct. It can be implanted within the same surgical corridor that is used for a standard midline decompression. The MINI is anchored with trans-articular pedicle screws that cross the facets and

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pedicle screws (standalone TFPS) and the MINI (Chart 1, p<0.02).

The load to failure analysis showed that the MINI withstood significantly higher loads (30%) compared to transfacet pedicle screws standalone (Chart 2, p=0.01).

Chart 2. Load to failure analysis comparing FacetLINK Mini vs Standalone Transfacet Pedicle Screws.

Chart 1: ROM Comparison: Normal vs. FacetLINK MINI vs. Standalone Bilateral Transfacet Pedicle Screws vs. Bilateral Pedicle Screws. terminate at the base of the pedicle. An adjustable monorail rigidly connects the screws for additional stability (Figs 2-4).

Following the midline decompression, the flanges of the MINI dock onto the pars and the device is fixed to the bone with screws containing a cortical thread form. The starting point for the screws is significantly medial to the starting point for traditional pedicle screws, and the screws are directed caudally and laterally resulting in the potential for placement within a smaller medial-lateral and cephalo-caudal exposure as compared to conventional fixation.

The MINI’s cross-connector assembly has been designed to add stability to the construct, and a series of biomechanical studies were performed to evaluate its performance. Segmental flexibility testing was conducted to compare the performance of the MINI device to 1.) independently placed (standalone) transfacet pedicle screws and 2.) bilateral pedicle screws and rods utilizing human cadaveric 10

specimens (n=8) with intact discs following complete laminectomies. Afterwards, load to failure was compared between the MINI device and traditional standalone transfacet pedicle screws.

In a second set of specimens, cyclical load testing was performed to evaluate the performance of the MINI under repetitive loads similar to those seen after implantation.

Five specimens were implanted with the MINI following bilateral decompression, and four specimens were implanted with standalone transfacet pedicle screws placed onto intact posterior elements (no decompression). Pre- and post-cyclical segmental range of motion (ROM) and stiffness values were recorded following non-destructive cyclic loading, initially in flexion-extension followed by lateral bending coupled with axial torsion over a total of 5,000 cycles.

During segmental flexibility testing, ROM with the MINI device trended towards greater stability compared to bilateral pedicle screws and rods (Bilat PSR) during flexion, extension and axial rotation, but this did not reach statistical significance (p>0.3). During lateral bending, Bilat PSR demonstrated statistically significant reduction in ROM compared to standalone transfacet

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In comparison to standard lumbar instrumentation, the MINI demonstrated similar initial stability, statistically improved load to failure, and greater stiffness and stability after cyclical loading. A potential advantage is that the MINI can be placed through the same small midline approach used for lumbar laminectomy, sparing the additional lateral soft tissue dissection that would be necessary to implant conventional pedicle screw and rod instrumentation.

References 1. King D: Internal fixation for lumbosacral fusion. J Bone Joint Surg Am 1948;30(3): 560-565.

Boucher HH: Method of spinal fusion. Clin Orthop Relat Res 1997;335:4-9.

2. Ferrara L et al: A biomechanical comparison of facet screw fixation and pedicle screw fixation. SPINE 2003;28(12): 1226-34 3. Agarwala A, Bucklen B, Muzumdar A, Moldavsky M, Khalil S: Do facet screws provide the required stability in lumbar fixation?: A biomechanical comparison of the Boucher technique and pedicular fixation in primary and circumferential fusions. Clin Biomech (Bristol, Avon) 2012;27(1):64-70 4. Molina et al: Transfacet screws with lumbar interbody reconstruction. J Spinal Disord 1996;9: 425–32.

POINT-COUNTERPOINT

The Direct-Look LLIF Technique: A Natural Evolution of a Minimally Invasive Surgery Choll W. Kim MD PhD1, Joseph O’Brien MD2, Chad Prusmack MD3, and counterpoints by Ivan Cheng MD4 1 Spine Institute of San Diego, San Diego CA, 2The Orthopaedic Center, Washington DC, 3the Rocky Mountain Spine Clinic, Denver CO, 4Stanford University, Stanford CA

jury to the psoas muscle itself. The psoas muscle is a delicate muscle that is easily traumatized during finger dissection of the retroperitoneal space and with insertion of the initial dilator. With increased psoas trauma, there is the greater risk of hip flexor weakness, referred pain to the anterior thigh, and neuritis of the lumbar plexus due to swelling The lateral lumbar interbody fusion and inflammation within the psoas (LLIF) technique, also known as muscle itself. While these sympXLIF and DLIF, is a cornerstone of toms tend to be relatively mild and minimally invasive spine surgery.1 temporary, they are common.2 Like all new surgical techniques, it’s safety and efficacy is dependent Many surgeons have independently on factors that, in some way, affect migrated to a modified technique the learning curve. Success in the where the surgical corridor is first few cases may depend on the directly visualized during dilaexperience and skill of the surgeon, tion of the surgical corridor. The the degree of preparation and train- published literature on this issue ing for the first case, along with the remains equivocal as the few studinherent difficulty of the surgical ies that have been published suffer technique. from small sample size.3-5 The LLIF technique, best known as the XLIF technique, was originally described as a purely percutaneous, fluoroscopically guided technique.

The 2-incision technique facilitates dissection of the retroperitoneal space and passage of the initial dilator through the psoas muscle while simultaneously palpating the dilator and psoas muscle the 2nd exposure window. In experienced hands, the 2-incision technique, together with neuromonitoring, has proven to be a safe strategy.

When performed percutaneously, the LLIF procedure poses several unique challenges. The first is in-

While the Direct-Look LLIF technique continues to gain popularity, the largest body of literature currently supports the use of integrated neuromonitoring with percutaneous dilation in the XLIF technique.6 Cheng et al5 performed a direct comparison of postoperative neural deficits in traditional XLIF and direct look approaches for lateral interbody fusion. In a 120 patient series, the authors found nearly double the neural complication rate (including sensory deficits) for direct look compared to the lateral transpsoas approach overall (28% vs. 14.2%, respectively), and nearly triple the rate in single

level procedures (28.6 % vs 10.2%, respectively). Yuan et al3 found similar results comparing XLIF with direct look approaches having total new postoperative neural effects of 33% compared to 42% with the conclusion that, “Direct visualization does not obviate neurologic side effects [in lateral transpsoas surgery].”

Given the large amount of literature that shows that neural injury is not avoided with the use of integrated neuromonitoring, Acosta et al. suggested that fewer nerve injuries are seen in a direct look approach.4 The authors reported no neural, vascular, or intra-abdominal injuries, though they reported one new lower extremity weakness postoperatively, which resolved. In terms of hip flexion weakness, some may argue that the direct look approach may actually exacerbate hip flexion weakness postoperatively as meticulous muscle fiber splitting may traumatize the muscle more than blunt dilator and retractor passage under evoked EMG. On the other hand, the lack of methodology used for data collection related to hip flexion weakness7 from the few currently available direct look reports indicate that the results remain preliminary but promising.

Editor Commentary I want to personally thank Choll and Ivan for putting together a very timely article that is very relevant to lateral transpsoas surgery. Unfortunately, the studies are small

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and underpowered and I would urge caution in using the literature to support one side or the other.

As we begin to understand the psoas and lumbar plexus, we learn that the anatomy is intricate and delicate. Neural injuries associated with a transpsoas approach have lessened with increasing experience. Those surgeons who are very proficient will cite that neural injury is most directly correlated with retraction time. Direct neural injury is less likely than prolonged and unintentional neural retraction.

While a direct look may guarantee that no nerve is directly in the path of the dilator, it does not resolve the retraction concerns. In addition, dissection through the psoas is not atraumatic as well. Regardless, we as surgeons can agree that the lateral transpsoas approach is a very effective tool for the spine surgeon, but it still requires advancement and improvement both in technique and neuromonitoring. -Kern Singh

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References 1.

Bach K, Ahmadian A, Deukmedjian A, Uribe JS. Minimally invasive surgical techniques in adult degenerative spinal deformity: a systematic review. Clinical orthopaedics and related research 2014;472:1749-61.

2.

Gammal ID, Spivak JM, Bendo JA. Systematic Review of Thigh Symptoms after Lateral Transpsoas Interbody Fusion for Adult Patients with Degenerative Lumbar Spine Disease. Int J Spine Surg 2015;9:62.

3.

Yuan PS, Rowshan K, Verma RB, Miller LE, Block JE. Minimally invasive lateral lumbar interbody fusion with direct psoas visualization. J Orthop Surg Res 2014;9:20.

4.

Acosta FL, Jr., Drazin D, Liu JC. Supra-psoas shallow docking in lateral interbody fusion.

Neurosurgery 2013;73:ons48-51; discussion ons2.

5.

Cheng I, Briseno MR, Ar-

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rigo RT, Bains N, Ravi S, Tran A. Outcomes of Two Different Techniques Using the Lateral Approach for Lumbar Interbody Arthrodesis.

Global spine journal 2015;5:30814.

6.

Ozgur BM, Aryan HE, Pimenta L, Taylor WR. Extreme Lateral Interbody Fusion (XLIF): a novel surgical technique for anterior lumbar interbody fusion. Spine J 2006;6:435-43.

7.

Ahmadian A, Deukmedjian AR, Abel N, Dakwar E, Uribe JS. Analysis of lumbar plexopathies and nerve injury after lateral retroperitoneal transpsoas approach: diagnostic standardization. J Neurosurg Spine 2013;18:289-97.

POINT-COUNTERPOINT

Graft Biomaterials Matt Colman, MD Polyetherethylketone, or PEEK, has a long history as an advanced engineering thermoplastic polymer which can be injection molded, extruded, machined, worked into filament for 3D printing applications, or surface modified. This technology has found a foothold in orthopedic surgery and spine applications primarily because of its inertness, strength, machinability, stability in biologic environments, and modulus of elasticity similar to that of cortical bone.

As such, PEEK is an excellent material which produces optimal outcomes for common procedures in the neck and back. As a spacer for interbody fusion, major advantages of PEEK that are not found with many other materials include modulus matching with cortical bone. For example, the Young’s modulus of PEEK is approximately 4 gigapascals (GPa), compared to the 10-20 range for cortical bone and over 100 GPa for titanium metal. This implies more stress sharing and less subsidence of the cage into the cortical endplate. Although data are inconsistent, many studies comparing subsidence of PEEK and titanium cages clearly favor PEEK. Another advantage is radiolucency.

Whereas solid state metal or ceramic implants make intra-cage fusion columns difficult to see, PEEK allows for optimal visualization.

In more advanced settings such as spine oncology where both tumor surveillance imaging and need to deliver radiotherapy are common,

radiolucency is also a key benefit.

Lastly, fusion rates appear to be at least as good if not better than other materials based on several randomized control trials. Concerns over the biologic inertness of PEEK and the lack of bone-implant osseointegration are eased by these studies, which also imply that meticulous endplate preparation, judicious use of biologics, and the biomechanical soundness of supporting constructs are what create fusion, not necessarily the endplate-implant interface.

The commoditization of this homogenous and widely produced plastic should theoretically eventually lead to a cost effectiveness which cannot be matched by machined allograft, harvested autograft, or development of new advanced materials. This will be increasingly important in the era of value-based care. Overall, the attributes of PEEK discussed above make it an excellent substrate for producing radiolucent interbody devices which produce low rates of subsidence and high rates of fusion, with simplicity of engineering and time-tested results. If we look to develop newer or more advanced devices, we should ask whether this search is driven by an actual clinical problem or by the business of developing spinal implants.

Alpesh A. Patel MD, FACS We see novel materials in many aspects of our daily lives. From clothing and electronics to cars and airplanes, the development of novel

materials has lead to extraordinary innovations in technology and design. New materials have been a foundation of disruptive change.

Similarly, biomaterials in spine surgery offer a paradigm shift in patient care.

Specific to intervertebral interbody fusion, the transition from bone to PEEK represented the first step in this path. Bone graft, though most widely reported, has inherent inconsistencies. Variability in donor sources leads to uncertainties in the mechanical and biological properties of autograft as well as allograft bone. The creation of interbody devices using PEEK provided needed consistencies in structure and function. This allows for more consistency from procedure to procedure and thereby improves the outcomes of care provided to patients by minimizing poor outliers. Furthermore, some cultures and health systems do not allow for the use of allograft bone and, therefore, PEEK devices opened new markets for intervertebral fusion that previously did not exist.

PEEK, however, should now be looked at as a “version 1.0” improvement over historical graft options. New materials, such as metals and ceramics, provide significant improvements over the 1.0 tech of PEEK. PEEK, as an inert plastic, has been shown to create a surrounding fibrous tissue layer without osseous integration of the device. Ceramic products, like silicon nitride, to the contrary have been proven to promote osseous

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ongrowth while also preventing bacterial adhesion. Metal products have also demonstrated excellent osseous integration in hip and knee arthroplasty and offer the potential for effective translation into spine surgery. Taking these new materials into novel designs and manufacturing, such as 3D printing, pushes the envelope of possibilities by potentially decreasing production costs, improving imaging capabilities, and strengthening osseous integration.

I have personally been utilizing novel ceramic interbody devices for anterior lumbar interbody fusion and anterior cervical fusions for over 8 years with excellent results today. While additional clinical data is needed to provide high levels of evidence, novel biomaterials are an exciting advancement in the care of our patients that can be utilized through effective design to address the current clinical limitations of traditional bone and PEEK materials.

Whatâ&#x20AC;&#x2122;s new in Spine Coding for 2017?

Code changes for all medical specialties take effect on January 1, 2017 as a result of the CPT Editorial Panel process.

The American Medical Association (AMA) is responsible for Current Procedural Terminology (CPT) and has convened the CPT Editorial Panel to develop and maintain the nomenclature healthcare providers use to report medical procedures and services. The CPT Editorial Panel meets three times a year to evaluate code change proposals for new and emerging technology and is responsible for reorganizing and maintaining the code set. After codes are created or modified by the CPT Editorial Panel, they go before the Relative Value Update Committee (RUC), also convened by the AMA, to be valued. For more information on the RUC process and how to efficiently complete a RUC survey, you can find a 13-minute video prepared by the AMA at http://www.isass.org/s/vid.

The CPT Editorial Panel and the RUC processes are cyclical; code changes approved by the CPT Editorial Panel at the February 2015 meeting, the May 2015 meeting, and the October 2015 meeting take effect on January 1, 2017.

ISASS joined the AMAâ&#x20AC;&#x2122;s House of Delegates in June 2014. With a seat in the House of Delegates came the opportunity to participate as advisors to the CPT Editorial Panel and the RUC beginning in calendar year 2015. ISASS strives to represent our membership in all three of these forums. Be on the look out in the coming weeks for an ISASS educational coding resource detailing changes to surgical spine coding to help you and your practice prepare for spine coding in 2017 and beyond.

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NEW TECHNOLOGY

Multimodal Analagesia (MMA) in Spine Surgery: A New Way Forward Mark F. Kurd, MD, Kern Singh, MD in 1988 and popularized in 1993 by Kehlet and Dahl.5, 6 In 1993, MMA Most patients undergoing surgery was defined as multiple analgesic experience significant post-opermedications utilized in a synergisative pain.1 Inadequate peri-opertic manner to control pain while ative pain management may deminimizing side-effects of individcrease post-operative mobilization ual drugs due to decreased doses. and increase length of hospitalizaThis concept has evolved to include tion. Additionally, poorly managed pre-operative patient education, inacute post-operative pain analgesia tra-operative pain management and is associated with an increased risk post-operative pain protocols. The of developing chronic pain and orthopaedic literature, in particular delayed wound healing.2-4 total joint arthroplasty, supports the use of MMA for peri-operative The concept of multimodal analge- pain management.7 MMA protocols sia (MMA) was conceived by Wall for patients undergoing total hip

and total knee arthroplasty have demonstrated a decrease in pain, narcotic consumption and length of hospitalization.8 When combining multimodal peri-operative pain management with minimally invasive surgical techniques and an aggressive rehabilitation protocol, total hip arthroplasty patients have been safely treated as outpatients.9 Lumbar spine surgery is particularly painful, often requiring a multi-day hospitalization. Common post-operative analgesia protocols used in spine surgery include

Table 1: Literature Review Article

Source Population

Study Design/ follow up time

Intervention

Outcome (primary underlined)

Results

Bujak-Gizycka Pain Medicine 2012

Idiopathic Scoliosis N=60

RCT 48 hours postop

Amantadine PO vs placebo

Postop morphine use NRS Pain N/V/pruritis AE

Morphine consumption lower in amantadine group Lower NRS pain rating in hours 1-6 postop

Elder Neurosurgery 2010

Cervical Fusion N=50

Retrospective postop d 4

Bupivacaine infusion Vs usual care

Pain on VAS Nactotic usage DC milestones Length of stay Postop complications

Less narc use on POD 1-4 Lower pain ratings Achieved DC milestones sooner

Jirarattanaphochai L spine Spine discectomy 2008 decompression or fusion N=120

RCT 48 hours postop

Parecoxib Vs placebo

Amount of Morphine use Pain intensity Pt satisfaction AE

Reduced morphine use by 39% Reduced pain at rest Greater patient satisfaction

Cata J Neurosurg Anesthesiol 2008

Retrospective 48 hrs postop

Epidural PCA Vs IVPCA

Pain intensity (via EMR) Opiate use DVT LOS

Improved pain in Epidural group (5 vs 4) Less mg morphine used in Epidural group

Morphine consumption Pain intensity Back pain (3 mo) Leg pain (3 mo) Oswestry (3 mo) SF 36 (3 mo)

Decreased morphine use Decreased postop pain on rest No difference in oswestry and SF 36

Consecutive spinal procedures N=245

Jirarattanaphochai Elective L Spine spine surgery 2007 N=103

RCT steroid+bupivacaine 48 hours postop to nerve root * some secondary Vs placebo outcomes to 3 mo

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Article

Source Population

Study Design/ follow up time

Intervention

Outcome (primary underlined)

Results

Kim Spine 2011

Elective L spine fusion N=84

RCT 48 hours postop

Pregabalin 75mg Pregabalin 150 mg placebo

Total PCA used Pain intensity Frequency of analgesic rescue N/V/drowsiness Satisfaction AE

150 mg pregabalin group had less IVPCA use than placebo No differences in pain or AE

Rajpal All spine J Spinal Disorders surgery 2010 N=200

Retrospective 24 hrs postop

MMA: ER oxy, gaba, aceta, dolasteron Vs IV PCA

Pain intensity Amount of opiates used

MMA had improved least pain rating, less opiate use MMA had fewer pts in mod-severe pain IVPCA had more N/V/ Drowsiness

Turan Anesthesiology 2004

L spine discectomy or fusion N=50

RCT 24 hours postop

1200 mg gabapentin 1 Pain intensity hr preop Vital signs, sedation Vs placebo AE

Pain scores at 1, 2, 4 hrs lower in gaba group Also used less morphine

Rasmussen Spine 2008

Primary L herniated disc N=200

RCT 2 years

Intraop steroid infusion to N root Vs placebo

Reoperation rates similar (7 vs 8%) Neuro impairment improved at 2 mo but not 1 or 2 yrs LOS shorter (6 vs 8 d) No difference in back pain No complications from intervention (dural tear, infection, neuro complications)

narcotic medication delivered via an intravenous patient controlled analgesia (IV PCA) or IV alone.

Several authors have studied innovative pain management protocols in spine surgery including oral amantadine, epidural PCA and bupivicaine infusions. Although these studies report reductions in post-operative morphine use and post-operative pain, these protocols have not been widely accepted by spine surgeons.10-12 Only one study compared MMA to a historical control of intravenous narcotic and reported reduced pain and less narcotic use in the MMA group.13 A comprehensive and current review of the literature is summarized in Table 1.

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Leg and back pain Neuro exam Length of stay

A multimodal peri-operative pain management protocol for spine surgery has the potential to not only decrease pain but also to improve recovery, decrease narcotic consumption, decrease length of stay in the hospital and reduce both direct and indirect hospital costs. The author’s preferred MMA protocol is presented in in Table 2.

References 1. Apfelbaum JL, Chen C, Mehta SS, Gan TJ. Postoperative pain experience: results from a national survey suggest postoperative pain continues to be undermanaged.

Anesth Analg 2003;97:534-540, table of contents.

2. Beilin B, Shavit Y, Trabekin E, et al. The effects of postoperative pain management on immune

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response to surgery. Anesth Analg 2003;97:822-827.

3. DeLeo JA, Tanga FY, Tawfik VL. Neuroimmune activation and neuroinflammation in chronic pain and opioid tolerance/hyperalgesia.

Neuroscientist 2004;10:40-52.

4. Shavit Y, Weidenfeld J, DeKeyser FG, et al. Effects of surgical stress on brain prostaglandin E2 production and on the pituitary-adrenal axis: attenuation by preemptive analgesia and by central amygdala lesion.

Brain Res 2005;1047:10-17.

5.Kehlet H, Dahl JB. The value of “multimodal” or “balanced analgesia” in postoperative pain treatment.

Anesth Analg 1993;77:1048-1056.

6. Wall PD. The prevention of postoperative pain. Pain 1988;33:289290.

7. Buvanendran A, Tuman KJ,

Table 2: MMA Protocol

for pain control in posterior cervical spine surgery: a case-control study.

Neurosurgery 2010;66:99-106; discussion 106-107.

13. Rajpal S, Gordon DB, Pellino TA, et al. Comparison of perioperative oral multimodal analgesia versus IV PCA for spine surgery. J Spinal Intraop - Propofol induction Disord Tech 2010;23:139-145.

- Sevoflorane maintenance, 14. Buvanendran A. Chronic post- Dexamethasone 10 mg IV induction, surgical pain: are we closer to under- Fentanyl 1mcg/kg/hour IV, standing the puzzle?. Anesth Analg.

- Ketamine 0.5 mg/kg IV induction and repeated dosing of 2012 Aug;115(2):231-2. doi: 10.1213/ 0.5 mg/kg every hour of case, - Marcaine 0.5% with Epinephrine injection (< 75 kg=20 cc ANE.0b013e318258b9f7.. per side, >75 kg=30 cc per side), 15. Liu SS, Buvanendran A, Rath- Zofran 4 mg IV (end of case) mell JP, Sawhney M, Bae JJ, Moric Postop First 24 hours: M, Perros S, Pope AJ, Poultsides - Acetaminophen 1000 mg PO q8h x 2 doses starting 8 L, Valle CJ, Shin NS, McCartney hours after first dose, CJ, Ma Y, Shah M, Wood MJ, - Pregabalin 75 mg PO q12h starting 12 hours after first Manion SC, Sculco TP. Predictors dose, for moderate to severe acute post- Tramadol 50 mg PO q4h starting 4 hours after first dose, - Cyclobenzaprine 10mg q8h starting 8 hours after first dose, operative pain after total hip and - Cryotherapy â&#x20AC;&#x201C; ice packs applied to back. knee replacement. Int Orthop. 2012 - Adjunct for breakthrough pain: Oxycodone IR 5 mg q4h Nov;36(11):2261-7. doi: 10.1007/ PO prn pain 4-6, 10mg q4h PO prn pain 7-10, s00264-012-1623-5. Epub 2012 Jul - Adjunct for breakthrough pain (PACU Only): Fentanyl 29.

50mcg IV with approval of attending (one time dose only) 16. Liu SS, Buvanendran A, RathAfter 24 hours: mell JP, Sawhney M, Bae JJ, Moric - Norco 5/325mg PO, 1 prn every 4-hours for pain 1-5, 1 pill M, Perros S, Pope AJ, Poultsides L, Norco 10/325 mg PO prn every 4-hours for pain 6-10, Della Valle CJ, Shin NS, McCart- Cyclobenzaprine 10 mg q8h prn spasm, ney CJ, Ma Y, Shah M, Wood MJ, - Acetaminophen 650 mg PO q6h prn temp greater than Manion SC, Sculco TP. A cross-sec101.5 tional survey on prevalence and risk Discharge - Norco 5/325mg, 1-2 pills PO q4-6hr prn pain. factors for persistent postsurgical - Cyclobenzaprine 5mg, 1 pill q8h prn spasm. pain 1 year after total hip and knee McCoy DD, Matusic B, Chelly JE. thop Relat Res 2009;467:1424-1430. replacement. Reg Anesth Pain Med. Anesthetic techniques for minimally 10. Bujak-Gizycka B, Kacka K, Suski 2012 Jul-Aug;37(4):415-22. doi: invasive total knee arthroplasty. J M, et al. Beneficial effect of amanta- 10.1097/AAP.0b013e318251b688.

Knee Surg 2006;19:133-136. dine on postoperative pain reduction 17. Young A, Buvanendran A. 8. Maheshwari AV, Blum YC, Shek- and consumption of morphine in Recent advances in multimodal har L, Ranawat AS, Ranawat CS. patients subjected to elective spine analgesia. Anesthesiol Clin. 2012 Multimodal pain management after surgery. Pain Med 2012;13:459-465. Mar;30(1):91-100. doi: 10.1016/j. total hip and knee arthroplasty at the 11. Cata JP, Noguera EM, Parke E, anclin.2011.12.002. Epub 2012 Jan Ranawat Orthopaedic Center. Clin et al. Patient-controlled epidural 12.

Orthop Relat Res 2009;467:1418analgesia (PCEA) for postopera1423. tive pain control after lumbar spine 9. Berger RA, Sanders SA, Thill ES, surgery. J Neurosurg Anesthesiol Sporer SM, Della Valle C. Newer 2008;20:256-260. anesthesia and rehabilitation proto12. Elder JB, Hoh DJ, Liu CY, Wang cols enable outpatient hip replaceMY. Postoperative continuous ment in selected patients. Clin Orparavertebral anesthetic infusion Preop (Given within 2 hrs of - Counseling and information surgery) - Pregabalin 150 mg PO - Oxycodone IR 10 mg PO, - Acetaminophen (Ofirmev) 1000 mg IV (given 1-hour prior to incision), - Transdermal Scopolamine patch (not in patients with BPH, glaucoma), - Cyclobenzaprine 10 mg PO

Vertebral Columns â&#x20AC;˘ Summer/Fall 2016

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Vertebral Columns â&#x20AC;¢ Summer/Fall 2016

PAIN CONTROL

Liposomal bupivacaine for post-operative pain control in MIS spine procedures Seth K. Williams, MD, Federico P. Girardi, MD

standard bupivacaine occurs over an approximately 72-hour period as the lipid membranes dissolve. The Liposomal bupivacaine has not Exparel® formulation includes a been studied in spine surgery, but it small amount of free standard buis being used in minimally invasive pivacaine that produces early local spine surgical (MIS) procedures anesthesia. The wholesale cost of in an attempt to achieve a longer liposomal bupivacaine is several duration of local anesthesia comhundred dollars, compared to just pared to standard bupivacaine. The three dollars for standard bupivatransforaminal lumbar interbody caine. fusion (MIS TLIF) is an example, in which case many surgeons curRandomized controlled trials rently use bupivacaine or lidocaine examining the safety and efficacy with epinephrine injected into the of liposomal bupivacaine have been subcutaneous tissues and muscle performed for a small number of in the relatively small operative procedures, including inguinal corridor both to control bleeding hernia repair, hemorrhoidectomy, during the surgery and for pain breast augmentation, total knee control post-operatively. Lidocaine arthroplasty (TKA), and buniois considered to be a short-acting (2 nectomy. FDA approval was – 3 hours) anesthetic and standard based on a bunionectomy trial and bupivacaine a long-acting (6 – 8 a hemorrhoidectomy trial.1,2 In hours) anesthetic. Some surgeons these trials, liposomal bupivacaine have begun using liposomal bupiwas compared to placebo over a vacaine in addition to, or instead 72-hour post-operative period. It of, lidocaine or bupivacaine during is important to note that liposomal their MIS TLIF procedures. It bupivacaine was not compared is not yet clear whether there is a to standard bupivacaine. In both clinical benefit. studies, the liposomal bupivacaine group experienced less pain than Liposomal bupivacaine (Exparel®) the placebo group at up to 24 hours is a longer-acting local anesthetic post-operatively, but there was that is FDA approved for use at minimal to no difference beyond the surgical site for local analgesia.

24 hours. There are only three Liposomal bupivacaine has the liposomal bupivacaine studies in same basic chemical structure and the orthopaedic surgery field, all pharmacologic properties as stanin TKA patients.3,4,5 Two of the dard bupivacaine, the difference studies showed no benefit to lipobeing that the bupivicaine is encap- somal bupivacaine, and the third sulated in liposomes with a median showed improved pain control only size of 24 – 31 μm. Slow release of when patients were at rest and only

at certain time periods, with the other efficacy measures showing no difference. Despite the lack of data showing safety and efficacy, marketing materials appeared to promote the use of the drug in surgeries other than bunionectomy and hemorrhoidectomy. The manufacturer of Exparel® therefore received a FDA warning letter in late 2014 because the drug was being marketed for surgical procedures other than those for which it was shown to be safe and effective, and for suggesting that the drug was more effective than had been demonstrated.

An important drug interaction to consider is the effect of local anesthetics on liposomal bupivacaine when injected either simultaneously or within a narrow time frame.

Lidocaine can lyse the liposomal membranes and lead to early release of the encapsulated bupivacaine. Standard bupivacaine when injected prior to liposomal bupivacaine may affect the pharmacokinetics of the liposomal bupivacaine, although this apparently happens only when the dose of standard bupivacaine exceeds 50% of the dose of liposomal bupivacaine. These effects may have implications for surgeons who use lidocaine or bupivacaine with epinephrine as a means of effecting vasoconstriction and minimizing blood loss. Mixing an epinephrine solution and using this along with liposomal bupivacaine instead of lidocaine or bupivacaine with epinephrine has

Vertebral Columns • Summer/Fall 2016

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not been studied, but is not recommended because of the potential to cause liposomal rupture. The drug company’s prescribing information states that liposomal bupivacaine can be administered safely 20 minutes after lidocaine administration.

From a safety perspective, liposomal bupivacaine appears to have a similar safety profile when compared to standard bupivacaine. It is specifically recommended that liposomal bupivacaine not be used in epidural, intrathecal, or regional nerve block applications. This is due to the prolonged action of the medication. Cardiac events are the main concern when there is an overdose. Standard bupivacaine is myotoxic at higher doses, and liposomal bupivacaine has not been studied as an intra-muscular injection, as it would be used in MIS TLIF and other MIS spine procedures. 6 In summary, there is not currently any data to support the use of liposomal bupivacaine in lieu of standard bupivacaine for MIS spine procedures. Randomized double-blinded trials are needed to determine if it is superior to standard bupivacaine. It will not be enough to show only that liposomal bupivacaine is superior to placebo, as was the case in the bunionectomy and hemorrhoidectomy trials.

We do not know if the potentially myotoxic effects are of legitimate concern, or if this is more of a theoretical risk that does not have clinical significance. Basic science research could likely answer this question. Ultimately we need to have well designed basic science studies and clinical studies specific to MIS spine procedures to guide us in choosing whether or not to use this medication. Only then 20

will we know if it is safe, and if it is clinically and cost effective.

References 1. Gorfine Sr et al: Bupivacaine extended-release liposome injection for prolonged postsurgical analgesia in patients undergoing hemorrhoidectomy: a multicenter, randomized, double-blind, placebo-controlled trial. Dis Colon Rectum 54(12): 1552-9, 2011.

2. Golf M et al: A phase 3, randomized, placebo-controlled trial of DepoFoam® bupivacaine (extended-release bupivacaine local analgesic) in bunionectomy. Adv Ther 28(9):776-88, 2011.

3. Bramlett K et al: A randomized, double-blind, dose-ranging study comparing wound infiltration of DepoFoam bupivacaine, an extended-release liposomal bupivacaine, to bupivacaine HCl for postsurgical analgesia in total knee arthroplasty.

Knee 19(5):530-6, 2012 4. White S et al: Impact of liposomal bupivacaine administration on postoperative pain in patients undergoing total knee replacement.

Pharmacotherapy 35(5):477-81, 2015.

5. Schroer WC et al: Does Extended-Release Liposomal Bupivacaine Better Control Pain Than Bupivacaine After TKA? A Prospective, Randomized Clinical Trial. J Arthroplasty 2015 (Epub ahead of print).

6. Zink W and Graf BM. Local anesthetic myotoxicity. Reg Anesth Pain Med 29(4), 330-40, 2004.

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COMPLICATIONS

When can anti-platelet therapy be stopped after cardiac stenting?

Noah Moss, Senior Cardiology Fellow, creases the risk of bleeding but the Mt. Sinai Hospital, NY, NY risk is present even in those who discontinued aspirin 1 week prior to In patients with a history of ischsurgery. Both studies have several emic heart disease, the decision limitations including a small sample to maintain or discontinue antisize which leaves the possibility platelet agents in the perioperative that small difference in bleeding period is one that even the most rates between the different groups experienced clinician struggles were missed. Importantly, the with. The evaluation becomes even overall reported incidence of clinimore challenging when treating cally relevant postoperative epidurpatients with recent intracoronary al hematoma is low, ranging from stent placement who require spinal 0% to 1%4. Therefore, a large trial surgery. A compromise between would be required in order to power the risk of serious bleeding induced a study to detect significant differby maintaining the agents and the ences in this dreaded complication. risk of stent thrombosis if they are discontinued must be reached.

Implantation of drug eluting stents (DES) is the current standard of The traditional practice among spi- care for the treatment of coronary nal surgeons has been perioperative artery disease necessitating percucessation of all antiplatelet agents1 taneous intervention. Their develdue to the potential risk of inducopment has improved upon rates ing intraspinal bleeding which can of in-stent neointimal hyperplasia lead to the development of a spinal that was associated with bare metal epidural hematoma (SEH) and stents5. While restenosis rates ultimately spinal cord compression. have improved, DES have been The need for this practice is contro- associated with a higher risk of late versial and institutional protocols stent thrombosis (ST), defined as appear to be changing. A recently occurring more then 30 days post published case series by Cuellar et procedure, due to delayed neointial.2 found no appreciable increase mal coverage and thus prolonged in bleeding related complication exposure of blood to the prothromrates in patients with cardiac stents botic subendothelial constituents6. undergoing spine surgery that ST is a devastating outcome, with continued to take aspirin compared reported mortality rates ranging with patients who ceased aspirin from 11-42% with various factors therapy to surgery. Park et al.3 influencing this rate7. The concompared perioperative blood loss cerns of increased ST rates with among patients undergoing lumthe initial DES led to the developbar fusion at 2 or more levels with ment of newer generation DES. and without antiplatelet use. They The improved vascular healing and found that aspirin significantly inre-endothelialization properties of

these second generation DES has resulted in lower rates of ST8 and their use is now standard of care in this country. Fully bioabsorbable coronary stents, which may further reduce very late stent thrombosis, have been developed but are not yet commercially available in this country. The administration of dual antiplatelet therapy (DAPT), consisting of aspirin and a P2Y12-receptor inhibitor (current available formulation are clopidogrel, prasugrel and ticagrelor), following implantation of a DES significantly reduces the likelihood of coronary stent thrombosis9,10. The length of dual antiplatelet therapy (DAPT) following drug eluting stent placement is controversial and is the subject of many recent large clinical trials11-14. In these studies the length of treatment varied from 3 to 36 months. A meta-analysis that included 10 of these RCTs concluded, not unexpectedly, that shorter DAPT had overall lower rates of bleeding yet higher rates of stent thrombosis when compared with longer DAPT15. An interesting finding in the above study was that the benefit of longer DAPT on ST was significantly attenuated with use of second-generation DES compared with first generation DES. Rate of ST was only 0.4% with longer DAPT and 0.6% with shorter DAPT with the use of second-generation DES. Despite the available data there is no clear consensus on the optimal duration of therapy. Even the two major societal guidelines differ in their

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statements on the optimal duration of DAPT following PCI for stable coronary artery disease as the current American College of Cardiology/American Heart Association and the European Society of Cardiology recommend a minimum duration of 12 and 6 months, respectively16,17.

An area lacking in prospective trials is temporary discontinuation of DAPT for noncardiac surgery. The PARIS study18 was a 5000 patient prospective observational registry which set out to asses associations between different modes of DAPT cessation and cardiovascular risk following PCI. They found that compared with those remaining on DAPT, patients who had temporary DAPT interruption lasting up to 14 days for surgical necessity did not have an increased rate of thrombotic events. The authors did caution that overall rates of interruption (10.5% of the cohort) and adverse events were low, thereby limiting power to detect small differences.

In addition, whether cessation of only one antiplatelet agent versus cessation of both aspirin and a thienopyridine impacted outcomes was not evaluated; a detail important to our topic. It has been suggested that stent thrombosis occurs with greater frequency19 and earlier20 following temporary cessation of both antiplatelet agents in the perioperative period.

The so called “aspirin withdrawal syndrome”21, the stimulation of a platelet rebound phenomenon and a prothrombotic state following cessation of antiplatelet agents, may be partially responsible for these findings. Several other factors have been associated with an increased risk of ST aside from premature DAPT cessation and stent type.

Clinical factors include renal failure, diabetes, current malignancy, 22

acute coronary syndrome at initial presentation and lower left ventricular ejection fraction22,23. In addition, several angiographic features have significant prognostic implications22-24. When these factors are present the clinician must be more cautious in interrupting DAPT for elective surgery.

While high quality data regarding temporary cessation of DAPT prior to spine surgery is lacking, several conclusion can be drawn from the evidence reviewed above. The incidence of SEH and ST are low, with both occurring at rates <1% in the modern era but they are both dreaded outcomes with potentially devastating consequences. It is likely that an attempt to reduce the risk of one will come at the expense of the other. In general, a 6-month course of DAPT should be completed at minimum and elective spine surgery should be postponed to allow for this. Following this, strong consideration should be given to continuation of aspirin in the perioperative period as this has been shown to be safe. Ultimately, baseline clinical factors are better predictors of outcomes then antiplatelet interruption patterns.

Therefore, management of perioperative antiplatelet therapy should be determined by a consensus of the surgeon, anesthesiologist, cardiologist, and patient, who should weigh the relative risk of bleeding with that of stent thrombosis.

References 1. Korinth MC, Gilsbach JM, Weinzierl MR. Low-dose aspirin before spinal surgery: results of a survey among neurosurgeons in Germany. European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the Euro-

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pean Section of the Cervical Spine Research Society 2007;16:365-72.

2. Cuellar JM, Petrizzo A, Vaswani R, Goldstein JA, Bendo JA. Does aspirin administration increase perioperative morbidity in patients with cardiac stents undergoing spinal surgery? Spine 2015;40:629-35.

3. Park HJ, Kwon KY, Woo JH. Comparison of blood loss according to use of aspirin in lumbar fusion patients. European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society 2014;23:1777-82.

4. Glotzbecker MP, Bono CM, Wood KB, Harris MB. Postoperative spinal epidural hematoma: a systematic review. Spine 2010;35:E413-20.

5. Costa MA, Simon DI. Molecular basis of restenosis and drug-eluting stents. Circulation 2005;111:2257-73.

6. Joner M, Finn AV, Farb A, et al.

Pathology of drug-eluting stents in humans: delayed healing and late thrombotic risk. Journal of the American College of Cardiology 2006;48:193-202.

7. Claessen BE, Henriques JP, Jaffer FA, Mehran R, Piek JJ, Dangas GD. Stent thrombosis: a clinical perspective. JACC Cardiovascular interventions 2014;7:1081-92.

8. Palmerini T, Benedetto U, Biondi-Zoccai G, et al. LongTerm Safety of Drug-Eluting and Bare-Metal Stents: Evidence From a Comprehensive Network Meta-Analysis. Journal of the American College of Cardiology 2015;65:2496-507.

9. Leon MB, Baim DS, Popma JJ, et al. A clinical trial comparing three antithrombotic-drug regimens after coronary-artery stent-

ing. Stent Anticoagulation Restenosis Study Investigators. The New England journal of medicine 1998;339:1665-71.

10. Schomig A, Neumann FJ, Kastrati A, et al. A randomized comparison of antiplatelet and anticoagulant therapy after the placement of coronary-artery stents. The New England journal of medicine 1996;334:1084-9.

11. Mauri L, Kereiakes DJ, Yeh RW, et al. Twelve or 30 months of dual antiplatelet therapy after drug-eluting stents. The New England journal of medicine 2014;371:2155-66.

12. Feres F, Costa RA, Abizaid A, et al. Three vs twelve months of dual antiplatelet therapy after zotarolimus-eluting stents: the OPTIMIZE randomized trial. Jama 2013;310:2510-22.

13. Lee CW, Ahn JM, Park DW, et al. Optimal duration of dual antiplatelet therapy after drug-eluting stent implantation: a randomized, controlled trial. Circulation 2014;129:304-12.

14. Schulz-Schupke S, Byrne RA, Ten Berg JM, et al. ISAR-SAFE: a randomized, double-blind, placebo-controlled trial of 6 vs. 12 months of clopidogrel therapy after drug-eluting stenting. European heart journal 2015;36:1252-63.

15. Giustino G, Baber U, Sartori S, et al. Duration of dual antiplatelet therapy after drug-eluting stent implantation: a systematic review and meta-analysis of randomized controlled trials. Journal of the American College of Cardiology 2015;65:1298-310.

16. Levine GN, Bates ER, Blankenship JC, et al. 2011 ACCF/AHA/ SCAI Guideline for Percutaneous Coronary Intervention: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Society

for Cardiovascular Angiography and Interventions. Circulation 2011;124:e574-651.

17. Authors/Task Force m, Windecker S, Kolh P, et al. 2014 ESC/ EACTS Guidelines on myocardial revascularization: The Task Force on Myocardial Revascularization of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS)Developed with the special contribution of the European Association of Percutaneous Cardiovascular Interventions (EAPCI). European heart journal 2014;35:2541-619.

18. Mehran R, Baber U, Steg PG, et al. Cessation of dual antiplatelet treatment and cardiac events after percutaneous coronary intervention (PARIS): 2 year results from a prospective observational study.

Lancet 2013;382:1714-22.

19. Kovacic JC, Lee P, Karajgikar R, et al. Safety of temporary and permanent suspension of antiplatelet therapy after drug eluting stent implantation in contemporary “real-world” practice. Journal of interventional cardiology 2012;25:482-92.

20. Eisenberg MJ, Richard PR, Libersan D, Filion KB. Safety of short-term discontinuation of antiplatelet therapy in patients with drug-eluting stents. Circulation 2009;119:1634-42.

21. Gerstein NS, Schulman PM, Gerstein WH, Petersen TR, Tawil I. Should more patients continue aspirin therapy perioperatively?: clinical impact of aspirin withdrawal syndrome. Annals of surgery 2012;255:811-9.

22. Iakovou I, Schmidt T, Bonizzoni E, et al. Incidence, predictors, and outcome of thrombosis after successful implantation of drug-eluting stents. Jama 2005;293:2126-30.

23. van Werkum JW, Heestermans AA, Zomer AC, et al. Predictors of coronary stent thrombosis: the Dutch Stent Thrombosis Registry.

Journal of the American College of Cardiology 2009;53:1399-409.

24. Cutlip DE, Baim DS, Ho KK, et al. Stent thrombosis in the modern era: a pooled analysis of multicenter coronary stent clinical trials.

Circulation 2001;103:1967-71.

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