Vertebral Columns, Summer 2018

Vertebral Columns International Society for the Advancement of Spine Surgery

Summer 2018

Cover: Public Domain vertebra sketch; Interior: Ibid.

In This Issue EDITORIAL Disclosure Involving Financial Relationships with Ambulatory Surgery Centers................................................................................................... 3 REVIEW NSAIDs in Spine Surgery...................................................................... 5 PROTOCOLS Care Pathways for Adult Spinal Deformity Surgery............................. 12 HOT TOPIC Stem Cells & Spinal Cord Injuries........................................................ 15 METASTASES The Role Of Percutaneous Instrumentation In The Treatment Of Spinal Metastases............................................................................................ 18 COMORBIDITIES The History, Evolution, and Current Use of Comorbidity Indices in Spine Research and Clinical Care.........................................................20

Editor in Chief Kern Singh Editorial Board Matthew Colman, MD Jeffrey Goldstein, MD Jonathan Grauer, MD Hamid Hassanzadeh, MD Safdar Khan, MD Mark Kurd, MD Yu-Po Lee, 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. © 2018 ISASS. All rights reserved.

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

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

ISSN 2414-6277.

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EDITORIAL

Disclosure Involving Financial Relationships with Ambulatory Surgery Centers Kern Singh, MD

The establishment of ambulatory surgical centers (ASC) have become a topic of much debate in the medical sector. The use of such centers has provided surgeons more efficient, convenient, and less expensive care for their patients. However, the development of ASCs have been theorized to create distrust from patients due to a lack of transparency in costs for surgical care and disclosure of financial relationships. As health care costs and insurance premiums continue to rise, patients demand more transparency regarding their healthcare expenses and any financial incentives that have potential to affect quality of care.

The rise of ASCs has become integral in the changing landscape of surgical care. Proponents such as Mitchell et al. advocate that ASCs are necessary in alleviating the cost burden on patients by increasing operating room efficiency, eliminating overhead expenses, and reducing need for extended hospital stay. Additionally, Erickson et al. describe the cost saving benefit up to 50% on common outpatient spine surgeries when compared to the traditional hospital setting. ASCs have demonstrated to not only be advantageous in healthcare cost and savings, but also be effective in

delivering quality patient care. In their study, Pugely et al. concluded that short-term complications rates were significantly lower in outpatient procedures compared to procedures in the inpatient setting.

Furthermore, Sivaganesan et al. established that ACSs enhance cost utilization, safety, and effectiveness for outpatient spine surgeries and argued with the continued advancements of perioperative analgesia and surgical technologies, minimally invasive and other low risk procedures may also transition to the outpatient setting.

While ASCs have proven cost efficiency and safety to patients, physician self-referral remains a topic of debate. Established in 1989, the Stark Law prohibits any economic conflict of interest in physician referral. However, ASCs were excluded from this law, making it possible for physicians to refer their patients to ASCs in which they are stakeholders. Friedly et al. suggest that this type of structure encourages financial conflict of interests for surgeons practicing in their ASCs and can potentially affect their physician-referral behavior. Additionally, Mitchell et al. demonstrate that there exists a financial incentive in ownership of an ASC or outpatient specialty hospital that influences physicians’ practice patterns. The authors suggest that such practice patterns are influenced by financial incentives to treat healthier patients with private insurance.

With the increasing costs of healthcare and rising insurance deductibles, patients have demanded more transparency for their healthcare costs. Metha et al. established how increased price transparency in surgical centers demonstrated an overall benefit for growth. Within the first year of making prices transparent, these ASCs established an increase in patient volume and patient satisfaction. Metha et al. found the primary barrier to current price transparency was discouragement from other practices, hospitals, and/or insurance companies. Nevertheless, as the shift for more outpatient surgical care grows, it is imperative for ASCs to become more transparent in regards to procedure costs. In doing so, providers will build patient trust and satisfaction and patients will become more engaged in their own medical care.

The growing use of ASCs suggests the benefit of price transparency and the need for disclosure for further patient engagement and satisfaction. ASCs represent the present and future of orthopedic care. These highly specialized facilities allow physicians to be the primary drivers of quality, safety and cost-efficiency. As always, physicians should err on the side of full disclosure with their patients regarding their ownership interests in these ASC.

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References 1. Mehta A, Xu T, Bai G, Hawley KL, Makary MA. The Impact of Price Transparency for Surgical Services. Am Surg. 2018;84(4):604608.

2. Sinaiko AD, Rosenthal MB. Increased price transparency in health care--challenges and potential effects. N Engl J Med. 2011;364(10):8914.

3. Mitchell JM. Effect of Physician Ownership of Specialty Hospitals and Ambulatory Surgery Centers on Frequency of Use of Outpatient Orthopedic Surgery. Arch Surg. 2010;145(8):732– 738. doi:10.1001/archsurg.2010.149 4. Erickson M, Fites BS, Thieken MT, et al.

Outpatient anterior cervical discectomy and fusion. American journal of orthopedics-belle mead- 2007;36:429.

5. Bekelis K, Missios S, Kakoulides G, et al.

Selection of patients for ambulatory lumbar

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discectomy: results from four US states. The Spine Journal 2014;14:1944-50.

6. Pugely AJ, Martin CT, Gao Y, et al. Outpatient surgery reduces short-term complications in lumbar discectomy: an analysis of 4310 patients from the ACS-NSQIP database. Spine 2013;38:264-71.

7. Sivaganesan A, Hirsch B, Phillips FM, Mcgirt MJ. Spine Surgery in the Ambulatory Surgery Center Setting: Value-Based Advancement or Safety Liability?. Neurosurgery.

2018;83(2):159-165.

8. Idowu OA, Boyajian HH, Ramos E, Shi LL, Lee MJ. Trend of Spine Surgeries in the Outpatient Hospital Setting Versus Ambulatory Surgical Center. Spine. 2017;42(24):E1429-E1436.

9. Best MJ, Buller LT, Eismont FJ. National Trends in Ambulatory Surgery for Intervertebral Disc Disorders and Spinal Stenosis: A 12Year Analysis of the National Surveys of Ambulatory Surgery. Spine. 2015;40(21):1703-11.

10. Friedly J, Standaert C, Chan L. Epidemiology of spine care: the back pain dilemma. Phys Med Rehabil Clin N Am. 2010;21(4):659-77.

REVIEW

NSAIDs in Spine Surgery Avani Vaishnav, MBBS; Zamie Abdullah; Mahie Abdullah; Catherine Himo Gang, MPH; Sheeraz Qureshi, MD, MBA

The use of Non-steroidal Anti-Inflammatory Drugs (NSAIDs) in spine surgery, despite extensive research of over 30 decades, remains a controversial topic. Although NSAIDs have shown significant benefit in terms of post-operative pain control, and reduction opioid consumption and opioid-related complications, concerns regarding increased risk of bleeding and impairment of bone healing, particularly in spinal fusion procedures, have resulted in the lack of clear recommendations regarding their use in spine surgery.

While studies in the 1990s focused on the use of NSAIDs, particularly indomethacin,1,2 ketorolac3–6 and propacetamol,7,8 for post-operative analgesia, research in the early 2000s saw a surge of studies focusing on the newly introduced selective COX-2 inhibitors.9–14 Ketorolac continues to be one of the most commonly studied drugs, with recent studies also assessing the bleeding risk associated with aspirin15–21 and the use of NSAIDs in multi-modal analgesia.22–26 A review of the recent evidence, published in the last 10 years, on the use of NSAIDs in spine surgery is presented below.

Pain control & Multi-modal analgesia Pre-operative Lumbar Decompression and Discectomy • A prospective randomized study

of patients undergoing lumbar laminectomy demonstrated that a multi-modal analgesic regimen consisting of celecoxib, pregabalin and oxycodone administered as a loading dose pre-operatively and repeated dosing every 12 hours post-operatively with supplemental PCA morphine as needed to, when compared to PCA morphine alone,23 results in better pain control and significantly lower morphine requirements, without an increased risk of any complications.

• A prospective randomized study of patients undergoing lumbar disc surgery comparing the analgesic efficacy of paracetamol-codeine, naproxen sodium – codeine to a placebo administered 30 minutes prior to surgery,27 along with post-operative PCA tramadol showed improved pain control and reduction in tramadol consumption with both, paracetamol-codeine and naproxen-codeine compared to PCA tramadol alone, with no difference between the two drugs in terms of pain control, but reduced tramadol consumption with paracetomal-codeine compared to naproxen-sodium codeine.

• A prospective randomized study of patients undergoing single-level lumbar discectomy comparing the analgesic efficacy of pre-operative single-dose administration of lornoxicam, paracetamol and a placebo28 showed better post-operative pain control and reduced rescue analgesic consumption with lornoxicam but not with paracetamol, as compared to the placebo.

• A prospective randomized double-blind study assessing the efficacy of single-dose etoricoxib given 1 hour before surgery on post-operative analgesia in patients undergoing single-level discectomy14 showed improved pain control, reduced PCA fentanyl consumption and improved sleep, without any side effects.

Lumbar Fusion • A prospective randomized double-blinded placebo controlled trial of patients undergoing posterior spinal fusion that compared the analgesic efficacy of pre-operative single-dose parecoxib, ketorolac to a placebo,29 followed by a standard post-operative analgesic protocol of paracetamol and intravenous morphine for rescue pain control showed better pain control with pre-emptive administration of either parecoxib and ketorolac, with no difference in pain reduction between the two. In addition, there was no difference post-operative opioid consumption, incidence of complications or bleeding.

• A prospective randomized double-blinded placebo control trial of patients undergoing posterior lumbar interbody fusion comparing the efficacy of a multimodal analgesia regimen, which consisted of pre-operative single-dose administration 1 hour prior to surgery and post-operative administration at pre-determined intervals of celecoxib, pregabalin, acetaminophen and extended-release oxycodone, with post-operative PCA morphine Vertebral Columns • Summer 2018

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to PCA morphine alone25 showed improved pain control with the multimodal analgesia regimen.

Intra-operative Lumbar Decompression and Discectomy • A randomized controlled double-blind study comparing the post-operative analgesia provided by single-dose administration of dexketoprofen 30 minutes before the end of surgery along with PCA tramadol to PCA tramadol alone in lumbar disc surgery30 showed significant benefit of dexketoprofen in terms of time to first post-operative analgesic requirement, total tramadol consumption, post-operative pain scores and post-operative nausea and vomiting, with no difference in other post-operative complications or adverse effects of medications.

• A randomized controlled double-blind study comparing intra-operative and post-operative analgesic effect of metamizol, paracetamol, lornoxicam and placebo in lumbar disc surgery31 showed improved pain control with metamizol and paracetamol, but not with lornoxicam. Additionally, there was no difference in overall opioid consumption.

Lumbar Fusion • A randomized controlled double-blind study comparing the analgesic efficacy of intra-operative administration of tenoxicam 30 minutes before wound closure followed by post-operative PCA using tenoxicam and morphine, to PCA using tenoxicam and morphine and PCA morphine alone in patients undergoing elective posterior spinal decompression and fusion with instrumentation32 demonstrated 6

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that although there was no difference in pain scores, the addition of tenoxicam intra-operatively and to the PCA regimen reduced with post-operative analgesic consumption.

Post-operative Lumbar Decompression and Discectomy • Randomized double-blinded trials have shown that administration of ketorolac in lumbar decompression33 and parecoxib in lumbar decompression and discectomy13 in the post-operative period reduces post-operative morphine requirements and provides better pain control compared to PCA morphine alone without a significant increase in the risk of bleeding, or other immediate complications.

• While one randomized double-blinded study comparing the analgesic efficacy and opioid sparing effect of single-dose pre-emptive administration of dexketoprofen trometamol or paracetamol34 in the post-operative period to PCA morphine alone for lumbar laminectomy showed equivalent analgesia and no difference in post-operative complications, with significant morphine-sparing effect seen with dexketoprofen but not with paracetamol, another study comparing the same analgesic agents35 showed better pain control with dexketoprofen, but not paracetamol when compared to PCA morphine alone, with no difference in opioid consumption or opiod-related adverse effects.

• A prospective randomized study of patients undergoing lumbar laminectomy demonstrated that a multi-modal analgesic regimen consisting of celecoxib, pregabalin and oxycodone administered as a

loading dose pre-operatively and repeated dosing every 12 hours post-operatively with supplemental PCA morphine as needed to, when compared to PCA morphine alone,23 results in better pain control and significantly lower morphine requirements, without an increased risk of any complications.

• A randomized controlled double-blind study comparing the analgesic efficacy of intra-operative administration of tenoxicam 30 minutes before wound closure followed by post-operative PCA using tenoxicam and morphine, to PCA using tenoxicam and morphine and PCA morphine alone in patients undergoing elective posterior spinal decompression and fusion with instrumentation32 demonstrated that although there was no difference in pain scores, the addition of tenoxicam intra-operatively and to the PCA regimen reduced with post-operative analgesic consumption.

• A prospective randomized study comparing PCA propacetamol and fentanyl to PCA fentanyl36 alone showed improved post-operative pain control and reduced rescue analgesic requirements with the addition of propacetamol to PCA fentanyl.

• A randomized controlled double-blind study comparing intra-operative and post-operative analgesic effect of metamizol, paracetamol, lornoxicam and placebo in lumbar disc surgery31 showed improved pain control with metamizol and paracetamol, but not with lornoxicam. Additionally, there was no difference in overall opioid consumption.

Lumbar Fusion

• A randomized double-blind trial has shown that administration of parecoxib,13 in the post-operative period in patients undergoing lumbar postero-lateral intertransverse fusion with pedicle screw fixation reduces post-operative morphine requirements and provide good pain control compared to PCA morphine alone without a significant increase in the risk of bleeding, or other immediate post-operative complications

Pre-operative Lumbar Decompression

• A prospective randomized study comparing PCA propacetamol and fentanyl to PCA fentanyl36 alone showed improved post-operative pain control and reduced rescue analgesic requirements with the addition of propacetamol to PCA fentanyl.

• A prospective randomized double-blind study assessing the efficacy of single-dose etoricoxib given 1 hour before surgery on post-operative analgesia in patients undergoing single-level discectomy14 showed no increase in intra-operative blood-loss.

• A prospective randomized double-blinded placebo control trial of patients undergoing posterior lumbar interbody fusion comparing the efficacy of a multimodal analgesia regimen, which consisted of pre-operative single-dose administration 1 hour prior to surgery and post-operative administration at pre-determined intervals of celecoxib, pregabalin, acetaminophen and extended-release oxycodone, with post-operative PCA morphine to PCA morphine alone25 showed improved pain control with the multimodal analgesia regimen.

Lumbar Fusion

• A retrospective database study of patients undergoing posterior spinal fusion for adolescent idiopathic scoliosis found that patients who received ketorolac for post-operative analgesia were less likely to have prolonged intravenous opioid exposure and prolonged length of hospital stay.

Bleeding risk

• A retrospective review of patients who discontinued low-dose aspirin prior to surgery to those who did not21 showed no difference intra-operative or post-operative blood-loss, with only one report of post-operative epidural hematoma in the aspirin continuation cohort and no difference in the incidence of cardiovascular complications.

• Low-dose aspirin is often prescribed for the prevention of cardiovascular disease. A retrospective review of patients who underwent lumbar fusion surgery, comparing patients who stopped aspirin 7 days before surgery to those who had never taken aspirin17 showed that although there was no difference in intra-operative blood-loss, patients who had taken aspirin had significantly greater post-operative blood-drainage after surgery, increased requirement for transfusion, increased utilization of intensive-care unit treatment and an increased occurrence of post-operative complications such as wound infection and epidural hematoma. A similar study comparing patients who took no aspirin to those who stopped aspirin 1 week before surgery and those who continued taking aspirin until the procedure18 showed that those who had consumed aspirin, regardless

of whether it was discontinued prior to surgery or not, had greater intra-operative and total blood loss, without an increased incidence of epidural hematoma or infection.

• A prospective randomized double-blinded placebo controlled trial of patients undergoing posterior spinal fusion that compared pre-operative single-dose parecoxib or ketorolac to a placebo,29 followed by a standard post-operative analgesic protocol of paracetamol and intravenous morphine for rescue pain control showed no difference in intra-operative blood loss or post-operative drain output.

• A retrospective review of patients who discontinued low-dose aspirin prior to surgery to those who did not21 showed no difference intra-operative or post-operative blood-loss, with only one report of post-operative epidural hematoma in the aspirin continuation cohort and no difference in the incidence of cardiovascular complications.

• A prospective randomized double-blinded placebo control trial of patients undergoing posterior lumbar interbody fusion comparing the efficacy of a multimodal analgesia regimen, which consisted of pre-operative single-dose administration 1 hour prior to surgery and post-operative administration at pre-determined intervals of celecoxib, pregabalin, acetaminophen and extended-release oxycodone, with post-operative PCA morphine to PCA morphine alone25 showed no difference in intra-operative blood-loss or post-operative drain output.

All spine surgeries • A retrospective review of patients Vertebral Columns • Summer 2018

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with cardiac stents undergoing spine surgery20 (cervical and lumbar, decompressions and fusions included) that compared blood-loss and bleeding-related complications in of those who continued taking aspirin prior to surgery to those who discontinued at least 5 days prior to surgery found no difference in blood-loss, requirement for transfusion or 30-day readmissions.

Additionally, no patient had a clinically significant epidural hematoma.

use of these drugs.

Intra-operative Lumbar Fusion

Lumbar Fusion

• A randomized controlled double-blind study comparing the analgesic efficacy of intra-operative administration of tenoxicam followed by post-operative PCA using tenoxicam and morphine, to PCA using tenoxicam and morphine and PCA morphine alone in patients undergoing elective posterior spinal decompression and fusion with instrumentation32 demonstrated no difference in intra-operative or post-operative bleeding.

Post-operative Lumbar Decompression and Discectomy • Randomized double-blinded trials have shown that administration of ketorolac in lumbar decompression33 and parecoxib in lumbar decompression and discectomy13 in the post-operative period showed no increase in the risk of bleeding, or other immediate complications • A randomized double-blind study comparing single-dose pre-emptive administration of dexketoprofen, trometamol, or paracetamol34 in the post-operative period to PCA morphine alone for lumbar laminectomy reported no bleeding complications associated with the 8

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• A prospective randomized study of patients undergoing lumbar laminectomy demonstrated that a multi-modal analgesic regimen consisting of celecoxib, pregabalin and oxycodone with supplemental PCA morphine as needed to, when compared to PCA morphine alone23 no difference in intra-operative blood-loss or post-operative wound drainage.

• A randomized double-blind trial has shown that administration of parecoxib,13 in the post-operative period following lumbar postero-lateral intertransverse fusion with pedicle screw fixation showed no increase in the risk of bleeding, or other immediate post-operative complications.

• A randomized controlled double-blind study comparing the analgesic efficacy of intra-operative administration of tenoxicam followed by post-operative PCA using tenoxicam and morphine, to PCA using tenoxicam and morphine and PCA morphine alone in patients undergoing elective posterior spinal decompression and fusion with instrumentation32 demonstrated no difference in intra-operative or post-operative bleeding.

• A prospective randomized double-blinded placebo control trial of patients undergoing posterior lumbar interbody fusion comparing the efficacy of a multimodal analgesia regimen, which consisted of pre-operative single-dose administration 1 hour prior to surgery and post-operative administration at pre-determined intervals of celecoxib, pregabalin, acetaminophen

and extended-release oxycodone, with post-operative PCA morphine to PCA morphine alone25 showed no difference in intra-operative blood-loss or post-operative drain output.

Fusion rate Pre-operative • A prospective randomized double-blinded placebo control trial of patients undergoing posterior lumbar interbody fusion comparing the efficacy of a multimodal analgesia regimen, which consisted of pre-operative single-dose administration 1 hour prior to surgery and post-operative administration at pre-determined intervals of celecoxib, pregabalin, acetaminophen and extended-release oxycodone, with post-operative PCA morphine to PCA morphine alone25 showed no difference in fusion rates.

Post-operative • A retrospective review on the use of ketorolac for post-operative pain control in patients undergoing posterior spinal fusion for Adolescent Idiopathic Scoliosis,37 adult patients undergoing lumbar postero-lateral intertransverse fusion with pedicle screw fixation,38 and pediatric patients undergoing spinal fusion39 showed no difference in the incidence of immediate post-operative complications or the development pseudoarthrosis.

• A retrospective review on the use of diclofenac sodium within 14 days after 1- and 2-level Posterior Lumbar Interbody Fusion (PLIF) surgery40 demonstrated a dose-dependent inhibition of fusion.

• A prospective randomized double-blinded placebo control trial

of patients undergoing posterior lumbar interbody fusion comparing the efficacy of a multimodal analgesia regimen, which consisted of pre-operative single-dose administration 1 hour prior to surgery and post-operative administration at pre-determined intervals of celecoxib, pregabalin, acetaminophen and extended-release oxycodone, with post-operative PCA morphine to PCA morphine alone25 showed improved pain control with the multimodal analgesia regimen.

Opioid-related complications Pre-operative Lumbar Decompression and Discectomy • A prospective randomized study of patients undergoing lumbar disc surgery comparing paracetamol-codeine, naproxen sodium –codeine to a placebo administered 30 minutes prior to surgery,27 along with post-operative PCA tramadol showed no difference in post-operative sedation, nausea or vomiting.

• A prospective randomized study of patients undergoing single-level lumbar discectomy comparing the analgesic efficacy of pre-operative single-dose administration of lornoxicam, paracetamol and a placebo28 no difference in post-operative nausea or vomiting.

Intra-operative Lumbar Fusion • A randomized controlled double-blind study comparing the analgesic efficacy of intra-operative administration of tenoxicam followed by post-operative PCA using tenoxicam and morphine, to PCA using tenoxicam and morphine and PCA morphine alone in patients undergoing elective posterior spinal decompression and fusion with in-

strumentation32 found that intra-operative administration of tenoxicam significantly reduced the incidence of post-operative skin itching.

• A randomized controlled double-blind study comparing intra-operative and post-operative analgesic effect of metamizol, paracetamol, lornoxicam and placebo in lumbar disc surgery31 showed no difference in post-operative nausea, vomiting or pruritus.

Post-operative Lumbar Decompression and Discectomy • A randomized double-blind study comparing single-dose pre-emptive administration of dexketoprofen trometamol or paracetamol34 in the post-operative period to PCA morphine alone for lumbar laminectomy reported no difference in post-operative nausea and vomiting despite the reported opiod-sparing effect of dexketoprofen.

• A prospective randomized study of patients undergoing lumbar laminectomy demonstrated that a multi-modal analgesic regimen consisting of celecoxib, pregabalin and oxycodone with supplemental PCA morphine as needed to, when compared to PCA morphine alone,23 results in earlier time to solid intake with multi-modal analgesia, possibly attributable to the opioid-sparing effect.

• A randomized double-blinded study comparing dexketoprofen with PCA morphine, paracetamol with PCA morphine and PCA morphine alone for lumbar disk surgery35 showed no difference in sedation, respiratory rate, nausea, vomiting, pruritus or urinary retention.

• A prospective randomized study comparing PCA propacetamol and fentanyl to PCA fentanyl36 alone showed a reduction in the incidence of post-operative nausea and vomiting in those who received propacetamol despite no difference in total fentanyl consumption.

• A randomized controlled double-blind study comparing intra-operative and post-operative analgesic effect of metamizol, paracetamol, lornoxicam and placebo in lumbar disc surgery31 showed no difference in post-operative nausea, vomiting or pruritus.

Lumbar fusion • A prospective randomized study comparing PCA propacetamol and fentanyl to PCA fentanyl36 alone showed improved post-operative pain control and reduced rescue analgesic requirements with the addition of propacetamol to PCA fentanyl.

Heterotopic Ossification Post-operative Cervical disc arthroplasty • A retrospective review of those who used NSAIDs following cervical disc arthroplasty41 to those who did not showed a non-significant trend towards lower heterotopic ossification in those who used NSAIDs, with no difference in clinical outcomes and no complications related to NSAID use.

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14. Srivastava S, Gupta D, Naz A, Rizvi MM, Singh PK. Effects of preoperative single dose

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Etoricoxib on postoperative pain and sleep after lumbar diskectomy: prospective randomized double blind controlled study. Middle East J Anaesthesiol. 2012;21(5):725-730.

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16. Goes R, Muskens IS, Smith TR, Mekary RA, Broekman MLD, Moojen WA. Risk of aspirin continuation in spinal surgery: a systematic review and meta-analysis. Spine J. 2017;17(12):1939-1946. doi:10.1016/j. spinee.2017.08.238.

17. Kang SB, Cho KJ, Moon KH, Jung JH, Jung SJ. Does low-dose aspirin increase blood loss after spinal fusion surgery?

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18. Park HJ, Kwon KY, Woo JH. Comparison of blood loss according to use of aspirin in lumbar fusion patients. Eur Spine J. 2014;23(8):17771782. doi:10.1007/s00586-014-3294-y.

19. Korinth MC, Gilsbach JM, Weinzierl MR. Low-dose aspirin before spinal surgery: Results of a survey among neurosurgeons in Germany.

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21. Soleman J, Baumgarten P, Perrig WN, Fandino J, Fathi AR. Non-instrumented extradural lumbar spine surgery under low-dose acetylsalicylic acid: a comparative risk analysis study.

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22. Devin CJ, McGirt MJ. Best evidence in multimodal pain management in spine surgery and means of assessing postoperative pain and functional outcomes. J Clin Neurosci. 2015;22(6):930-938. doi:10.1016/j. jocn.2015.01.003.

23. Garcia RM, Cassinelli EH, Messerschmitt PJ, Furey CG, Bohlman HH. A Multimodal Approach for Postoperative Pain Management After Lumbar Decompression Surgery. J Spinal Disord Tech. 2012;26(6):291-297. doi:10.1097/ BSD.0b013e318246b0a6.

24. Kurd MF, Kreitz T, Schroeder G, Vaccaro AR. The role of multimodal analgesia in spine surgery. J Am Acad Orthop Surg. 2017;25(4):260-268. doi:10.5435/ JAAOS-D-16-00049.

25. Kim S Il, Ha KY, Oh IS. Preemptive multimodal analgesia for postoperative pain management after lumbar fusion surgery: a randomized controlled trial. Eur Spine J. 2016;25(5):16141619. doi:10.1007/s00586-015-4216-3.

26. Rivkin A, Rivkin MA. Perioperative nonopioid agents for pain control in spinal surgery.

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27. Polat R, Peker K, Gülöksüz ÇT, Ergil J, Akkaya T. Comparison of the postoperative analgesic effects of paracetamol-codeine phosphate and naproxen sodium-codeine phosphate for lumbar disk surgery. Kaohsiung J Med Sci. 2015;31(9):468-472. doi:10.1016/j. kjms.2015.07.001.

28. Bilir S, Yurtlu BS, Hanci V, et al. Effects of peroperative intravenous paracetamol and lornoxicam for lumbar disc surgery on postoperative pain and opioid consumption: A randomized, prospective, placebo-controlled study. Agri. 2016;28(2):98-105. doi:10.5505/ agri.2015.45220.

29. Siribumrungwong K, Cheewakidakarn J, Tangtrakulwanich B, Nimmaanrat S. Comparing parecoxib and ketorolac as preemptive analgesia in patients undergoing posterior lumbar spinal fusion: A prospective randomized double-blinded placebo-controlled trial.

BMC Musculoskelet Disord. 2015;16(1):1-8. doi:10.1186/s12891-015-0522-5.

30. Yazar MA, Inan N, Ceyhan A, Sut E, Dikmen B. Postoperative analgesic efficacy of intravenous dexketoprofen in lumbar disc surgery. J Neurosurg Anesth. 2011;23(3):193-197. doi:10.1097/ANA.0b013e31820d1ebb.

31. Korkmaz Dilmen O, Tunali Y, Cakmakkaya OS, et al. Efficacy of intravenous paracetamol, metamizol and lornoxicam on postoperative pain and morphine consumption after lumbar disc surgery. Eur J Anaesthesiol. 2010;27(5):428-432. doi:10.1097/ EJA.0b013e32833731a4.

32. Chang W-K, Wu H-L, Yang C-S, et al. Effect on Pain Relief and Inflammatory Response Following Addition of Tenoxicam to Intravenous Patient-Controlled Morphine Analgesia: A Double-Blind, Randomized, Controlled Study in Patients Undergoing Spine Fusion Surgery. Pain Med. 2013;14(5):736-748. doi:10.1111/pme.12067.

33. Cassinelli EH, Dean CL, Garcia RM, Furey CG, Bohlman HH. Ketorolac use for postoperative pain management following lumbar decompression surgery: A prospective, randomized, double-blinded, placebo-controlled trial.

Spine (Phila Pa 1976). 2008;33(12):1313-1317. doi:10.1097/BRS.0b013e31817329bd.

34. Kesimci E, Gümüş T, Izdeş S, Şen P, Kanbak O. Comparison of efficacy of dexketoprofen versus paracetamol on postoperative pain and morphine consumption in laminectomy patients. Agri. 2011;23(4):153-159. doi:10.5505/ agri.2011.86548.

35. Tunali Y, Akçil EF, Dilmen OK, et al.

Efficacy of intravenous paracetamol and dexketoprofen on postoperative pain and morphine consumption after a lumbar disk surgery. J Neurosurg Anesthesiol. 2013;25(2):143-147. doi:10.1097/ANA.0b013e31827464af.

36. Kim EJ, Shim J-K, Soh S, Song JW, Lee SR, Kwak Y-L. Patient-controlled Analgesia With Propacetamol-Fentanyl Mixture for Prevention of Postoperative Nausea and Vomiting in

High-risk Patients Undergoing Spine Surgery: A Randomized Controlled Trial. J Neurosurg Anesthesiol. 2016;28(4):316-322. doi:10.1097/ ANA.0000000000000252.

37. Sucato DJ, Lovejoy JF, Agrawal S, Elerson E, Nelson T, McClung A. Postoperative ketorolac does not predispose to pseudoarthrosis following posterior spinal fusion and instrumentation for adolescent idiopathic scoliosis.

Spine (Phila Pa 1976). 2008;33(10):1119-1124. doi:10.1097/BRS.0b013e31816f6a2a.

38. Pradhan BB, Tatsumi RL, Gallina J, Kuhns CA, Wang JC, Dawson EG. Ketorolac and spinal fusion: Does the perioperative use of ketorolac really inhibit spinal fusion? Spine (Phila Pa 1976). 2008;33(19):2079-2082. doi:10.1097/ BRS.0b013e31818396f4.

39. Horn PL, Wrona S, Beebe AC, Klamar JE. A retrospective quality improvement study of ketorolac use following spinal fusion in pediatric patients. Orthop Nurs. 2010;29(5):342-343. doi:10.1097/NOR.0b013e3181edd876.

40. Lumawig JMT, Yamazaki A, Watanabe K. Dose-dependent inhibition of diclofenac sodium on posterior lumbar interbody fusion rates. Spine J. 2009;9(5):343-349. doi:10.1016/j. spinee.2008.06.455.

41. Tu T, Wu J, Huang W, et al. Postoperative nonsteroidal antiinflammatory drugs and the prevention of heterotopic ossification after cervical arthroplasty: analysis using CT and a minimum 2-year follow-up. 2015;22(May):447-453. doi:10.3171/2014.10.SPINE14333.Disclosure.

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PROTOCOLS

Care Pathways for Adult Spinal Deformity Surgery Ricardo Fontes, MD, PhD; Jamie Bloechl MSN Introduction As awareness of adult spinal deformity (ASD) increased over the past 15 years, providers have experienced the three-phase process characterizing the integration of ASD concepts and treatment plans into clinical practice: 1) initial excitement of offering a surgical treatment for patients initially relegated to palliation, 2) disappointment at staggering complication rates and 3) moderation and planning, which has enabled us to guide these patients through the perioperative period with excellent clinical results and acceptable morbidity.

ASD refers to a heterogenous group of spinal pathologies (e.g. degenerative, traumatic, infectious, congenital, and iatrogenic) manifested in adulthood. All of these pathologies share the spinal rigidity and decreased functional reserve of aging adults when compared to the prototypical deformity of adolescent idiopathic scoliosis (AIS). Pressure for surgical treatment is also greater since pain and decreased function are almost always present.1 Evolving from two traditional treatment algorithms (adolescent scoliosis and adult degenerative pathology), surgeons operating on ASD patients realized increased systemic complication rates with a greater need for osteotomies and long fixations to the pelvis.2 In a relatable fashion, cervical ASD is a completely new 12

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challenge in itself. Thus, resource utilization and complication data routinely lead to questioning of the overall utility of ASD.3 After initial results leading to severe morbidity and mortality, our institution (Rush University Medical Center) performed a root cause analysis demonstrating wide differences in expectations amongst the treatment teams involved in surgical care of these patients. At the base of this problem was deficient communication amongst these teams, ranging from primary care physicians clearing patients, improper scheduling of ASD cases, and immediate postoperative care in an inadequate setting, such as the regular spine floor.

Rush Neurosurgery Pathway

pioneer teams including Rajiv Sethi at Virginia Mason Medical Center (Seattle, WA), Tyler Koski at Northwestern University (Chicago, IL), and Christopher Shaffrey at the University of Virginia (Charlottesville, VA), we were able to create our own pathway.4,5 Fundamental to this concept is enhanced communication amongst treatment teams and the frequent intra- and postoperative assessment of the patient for hemodynamic and hematological status, of which most immediate and severe complications arise. As such, we have established a need for adjustments of our ASD protocols at Rush.

Preoperative Assessment and surgical planning

Crucial to many ASD pathways is the centralized multidisciplinary Drawing from the experience of Figure 1. Summary of preoperative stage of ASD pathway.

meeting with each member holding a vote or veto power. While we fully embrace the concept of multidisciplinary care from a patient, clinical, hospital or even legal perspective, responsibility and accountability are not equally shared amongst members of the multidisciplinary group.

Responsibility for complications are inevitably inherited unevenly by the treating surgeon, as the patient-physician contract is typically with the surgeon alone and not other members of the team. Other unique characteristics of Rush make the formal regular meeting unnecessary and less efficient as hospital-employed and private practice providers may have different interests and availabilities. Central to our setup is an academic, hospital-employed, deformity-oriented surgical team, creating a “cabinet-style” pathway with strong support from ancillary teams (Figure 1). Nonoperative care is handled by a different team (PM&R or Pain Management), and while the plan is managed together with the surgeons, medication management is strictly dissociated from surgical decision-making.

45-60 minutes.

Postoperative Care

Intraoperative Care

Due to a unique referral pattern in Chicago, our Neuroscience ICU frequently accepts neurovascular cases and an adaptation of a new protocol was necessary to receive what essentially are “trauma” cases. In order to avoid further deterioration of health, strict hematological surveillance with laboratory checks every 4 or 8 hours and aggressive transfusions are justified in these cases. Furthermore, a “leak test” is central to extubation of cervical deformity cases and discussed jointly with the spine service.8 To ensure compliance with the ASD pathway, attending-to-attending communication is ensured at the end of the case and at least daily.

Additionally, nursing and resident instructions are placed to quickly escalate care to the daily attending rounds when necessary.

Beginning with the OR staff, ASD cases require several adaptations.

While some centers advocate a “two-attending” team for deformity surgery as a means to decrease intraoperative complications, this may not be the most time- and resource-effective way to allocate two attending surgeons and may actually lead to increased postoperative complications.6,7 Instead, our Chief Residents and Fellows from a spine-heavy neurosurgery program will arrive at their senior year with over 1,000 spine cases and can function adequately as junior surgeons. Ideally, the same group of 2 or 3 anesthesiologists would perform these cases on a regular basis. In order to accommodate longer cases, our OR support staff including scrub nurses and radiology technicians are re-allotted to allow for an incoming shift from 3PM to 11PM. Besides the mandatory institutional “time-out”, we have established a “time-in” and “checkpoints”. The “time-in” is updated the day prior or the early Once pathway patients are identimorning of surgery to establish fied, bone health and systemic congoals, expectations, and bail-out ditions are evaluated and optimized points and ensure similar expectaprior to surgery. Besides the usual tions regarding the case. Similarly, medical evaluation, risk estimation the “checkpoint” consists of a and clearance for surgery, a visit to mini-update of patient status and the preoperative anesthesia clinic, surgery progress prior to five predeand pre-screening are necessary. Ad- termined points (instrumentation, ditionally, a baseline echocardiogram posterior osteotomies, interbody is obtained for critically ill patients. work, PSO/VCR and final correcAt any point, continuous re-evaltion) with the patient only advancing uation for a minimally invasive to the next stage if in appropriate (MIS) or a short-segment option is hemodynamic condition (Figure 2). performed and may be dictated by Scheduling delays leading to a late patient factors uncovered during start time, anesthesia concerns, or preoperative assessment. A final hemodynamic instability would be preoperative meeting discussing among the many reasons to interrupt risks and benefits of postoperative and stage a case. disposition is held, usually lasting

Conclusion The ASD pathway is unique when compared to other common spine surgery such as enhanced recovery after surgery (ERAS) or MIS pathway and reflects the complexity of the pathology and need for specialized teams. Surgical results in the literature are overwhelmingly in favor of a specialized surgical pathway to care for ASD patients. In our particular case, it enabled us to perform cases we were referring elsewhere with excellent results. In 2.5 years, 115 patients (126 surgeries) were successfully enrolled in this protocol with no reported mortality and only 2 unplanned stagings. We believe the development of specific clinical pathways for ASD to be one of the most exciting developments in this subspecialty and we strongly encourage other groups to develop their own protocols.

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Figure 2 – Summary of intraoperative stage of ASD pathway.

References 1. Scheer JK, Hostin R, Robinson C, Schwab F, Lafage V, Burton DC, et al. Operative Management of Adult Spinal Deformity Results in Significant Increases in QALYs Gained Compared to Non-operative Management: Analysis of 479 patients with Minimum 2-year Follow-up.

Spine. 2016 Apr 11; 2. Smith JS, Klineberg E, Lafage V, Shaffrey CI, Schwab F, Lafage R, et al. Prospective multicenter assessment of perioperative and minimum 2-year postoperative complication rates associated with adult spinal deformity surgery.

J Neurosurg Spine. 2016 Jul;25(1):1–14.

3. Scheer JK, Tang JA, Smith JS, Acosta FL Jr, Protopsaltis TS, Blondel B, et al. Cervical spine alignment, sagittal deformity, and clinical implications: a review. J Neurosurg Spine. 2013 Aug;19(2):141–59.

4. Sethi R, Buchlak QD, Yanamadala V, Anderson ML, Baldwin EA, Mecklenburg RS, et al. A systematic multidisciplinary initiative

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for reducing the risk of complications in adult scoliosis surgery. J Neurosurg Spine. 2017 Jun;26(6):744–50.

5. Zeeni C, Carabini LM, Gould RW, Bebawy JF, Hemmer LB, Moreland NC, et al. The implementation and efficacy of the Northwestern High Risk Spine Protocol. World Neurosurg.

2014 Dec;82(6):e815-823.

6. Ames CP, Barry JJ, Keshavarzi S, Dede O, Weber MH, Deviren V. Perioperative Outcomes and Complications of Pedicle Subtraction Osteotomy in Cases With Single Versus Two Attending Surgeons. Spine Deform. 2013 Jan;1(1):51–8.

7. Gomez JA, Lafage V, Scuibba DM, Bess S, Mundis GM, Liabaud B, et al. Adult Scoliosis Deformity Surgery: Comparison of Outcomes Between One Versus Two Attending Surgeons.

Spine. 2017 Jul 1;42(13):992–8.

8. Traynelis VC. Total subaxial reconstruction.

J Neurosurg Spine. 2010 Oct;13(4):424–34.

HOT TOPIC

Stem Cells & Spinal Cord Injuries Yu-Po Lee, MD

Introduction The use of stem cells has been considered in medicine for a long time now. Potential uses of stem cells in spine surgery include spinal fusion, disc regeneration, and treatment for spinal cord injuries. Injuries to the spine and spinal cord carry great morbidity and mortality. Currently, very few proven treatment options are available to treat patients who have sustained a spinal cord injury.

Intervertebral disc degeneration is another condition of the spine that can greatly affect patients. While many patients are able to manage their symptoms, many suffer greatly without a proven treatment option. Treatment a debilitating disc injury can include spinal fusion. However, regeneration of the disc would be a more physiologic solution. Lastly, spinal fusion is a very commonly performed spinal procedure. Iliac crest graft is the gold standard but there is a limited supply. The use of stem cells to augment spinal fusions would be another area where stem cells could be beneficial.

Review of Literature Stem Cells in Spinal Fusion In 2001, Deyo et al reported that over 122,000 lumbar fusions were performed for degenerative conditions in the United States. Unfortunately, rates of spinal fusion are

still variable with nonunion rates as high as 40% despite various techniques and technological advances.

Reasons for this are many, including the number or levels fused, smoking history, and patients’ medical co-morbidities.

The gold standard for spinal fusions is autogenous bone graft from the iliac crest. However, the procedure carries significant morbidity, such as bleeding, neurologic injury, gait disturbance, fracture, painful scar, and cosmetic defect. Allogenic bone is routinely used to reduce the morbidity of autografts. However, allogenic transplant always raises the issue of graft rejection, inflammation, and disease transmission.

Synthetic grafts may also be considered. Ideally, for spinal fusion, the graft must be osteoinductive, osteoconductive, and osteogenic. Bone graft substitutes have been shown to be osteoinductive and osteoconductive, but an osteogenic property has been elusive. The addition of stem cells to graft material, however, may be a means of introducing this property.

Basic science research shows strong evidence for the use of stem cells in spinal fusions. And there have been a few published clinical studies evaluating the efficacy of stem cells in spinal fusion surgery. Most studies evaluating cellular augmentation of bone grafts in spinal fusion use bone marrow aspirate (BMA) as the primary source of stem cells. BMA is harvested from the iliac crest intraoperatively and transplanted to the fusion site. It

is important to keep in mind that only 1/10 000 cells per BMA are mesenchymal stem cells in a young healthy patient, and this number is significantly lower in older patients. Given the variable quality of a patient’s stem cells due to age, health, smoking status, and other factors, BMA may not consistently yield cells to support fusion. This is an important point to keep in mind if the decision is made to use BMA in older patients. In these cases, it may be better to use mesenchymal stem cells (MSC) that were harvested and expanded in tissue culture prior to implantation in patients. When comparing BMA with commercially available stem cells, it appears that there may be a difference in the fusion rate between BMA and stem cells.

MSCs may be a good choice in a patient with poor marrow quality, but the data on its efficacy is limited. There have been a few retrospective reviews using MSCs in a spinal fusion with an average fusion rate of 89.3%. There are currently no studies involving spinal fusion where stem cells are isolated from the patient and expanded in vitro prior to implantation. Doing so would require considerable planning and expenses. However, this may be an area of study and development as medicine becomes more personalized.

The use of stem cells for spinal fusions appears promising. They are the osteogenic component necessary for bone formation. They may be especially effective in older patients because older patients have Vertebral Columns • Summer 2018

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fewer stem cells and this may be the reason why bone healing is more difficult in older patients. But more research needs to be done before they can be used with confidence in humans. Further areas of study include the optimal carrier for the stem cells as well as more studies evaluating the efficacy of stem cells in more challenging fusion surgeries such as in long scoliosis fusions or tumor reconstructions.

Stem cells in disc regeneration The human intervertebral disc (IVD) consists of the annulus fibrosus and the nucleus pulposus (NP). The annulus fibrosus is a mesenchymally derived structure that forms the outer ring of the intervertebral discs. This dense ring of collagen resists tensile loads placed on the spine by movements such was bending and twisting.

The outer layer is innervated, which, when torn, can cause low back pain. Contained within the annulus lies the nucleus pulposus.

As a gelatinous mass composed of water, proteoglycans and type 2 cartilage, it functions as a shock absorber, resisting compressive loads. As the water and proteoglycan content decreases with age, so does its functional ability.

In additional to the mechanical stresses placed on the IVD, there are several environmental stressors.

With the exception of the outer annulus, the disc is aneural. It also lacks sufficient vascularization and thus inhabits a hypoxic, acidic, and nutrient deficient environment.

This harsh environment impairs proteinase function, turnover of disc matrix molecules, and synthetic abilities. This harsh environment, however, provide a niche for a special type of stem cell.

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Since the human IVD seems incapable of repairing damage to the matrix, this may provide an avenue to allow stem cells to generate the components necessary to repair the matrix with an intrinsic “stop� mechanism due to limited stem cell viability. However, the damage may be so extensive that greater regeneration is needed.

Animal studies demonstrate that stem cells may play a role in the treatment of intravertebral disc degeneration in many ways. Stem cells may provide a matrix upon which native NP cells may expand.

Stem cells may also, through mechanisms not completely understood, allow the IVD to regenerate as evidenced by histologic evaluation, disc height, and disc water content.

The harsh environment of the IVD must be taken into account when considering stem cell therapy for disc degeneration. Whether stem cells can proliferate under these conditions or stabilize the environment so native cells may flourish is not well understood. However, with such promising animal studies and safety demonstrated in humans, stem cell therapy for degenerative discs should be examined further as a treatment option.

There are currently no published articles studying the efficacy of stem cells in disc regeneration in humans. However, there are a few clinical trials currently underway.

Stem cells in spinal cord injury Each year there are approximately 12,000 new spinal cord injuries (SCI) in the United States. These devastating and life altering injuries leave patients with varying levels of neurologic deficits, ranging from partial motor dysfunction at one or more levels to tetraplegia. As

medicine has advanced, patients are living for decades after their injury, thus leading to an increased prevalence of SCI patients. Health care providers focus on rehabilitation and coping with the remaining neurologic function but can offer nothing but watchful waiting as treatment for the actual injury.

Injury to the spinal cord involves three stages. The acute phase involves mechanical damage and cell death. The secondary phase involves a reactive gliosis where astrocytes lay down abberant glial fibers forming irregular tracts.

Apoptosis, inflammation and overall extension of the initial lesion occurs and extends into the chronic phase, resulting in a syringomyelia or a multilocular cavity, changes in membrane protein expression, and neural circuit remodeling.

With cell loss as a central part of spinal cord injury, cell replacement may be one treatment to consider and stem cells may be the vehicle.

But there are many key questions that must be answered before stem cells can be reliably used in humans with SCIs. More investigation into the best mode of administration must be performed. Intravenous injection provides easy and noninvasive access. However, intrathecal injections and direct transplantation could also be considered.

An equally important consideration includes the timing and dosage of the administration of stem cells.

Also, there is the question of the ideal location for implantation of the cells and the carriers and other associated factors that may promote the repair of an injured spinal cord. More thorough investigations into human application of stem cell therapy to SCI are needed.

Currently there are no published articles demonstrating the efficacy of stem cells in SCI patients. Randomized clinical trials to demonstrate the safety of stem cell use are needed, particularly pertaining to injection of stem cells into the spinal cord. Long term follow-up is also necessary to delineate if improvement is due to the natural course of SCI or to the therapeutic effects of stem cells. Studies should provide objective data, including SEPs and MEPs. In patients who have received stem cell therapy, future post-mortem examination may provide a better explanation into the therapeutic mechanism.

Promising results in animal studies and positive, although inconsistent, human cases provide hope for patients with SCI. Conclusion For difficult to treat diseases, especially those that cause long term loss of function, such as SCI and disc degeneration, stem cells provide a hope for advances in treatment. Basic science demonstrates the potential of stem cells to differentiate into a multitude of tissues capable of synthetic function.

Animal and human studies provide inconsistent data. However, the existence of positive results provides hope that stem cells may provide a therapeutic option. Structured clinical trials should be performed to evaluate the safety and efficacy of stem cell therapy in spinal fusion, disc regeneration, and spinal cord injury.

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METASTASES

The Role Of Percutaneous Instrumentation In The Treatment Of Spinal Metastases Seth K. Williams, MD

Spinal metastases present in a variety of ways. The patient’s neurological status is a surgeon’s typical immediate concern. Neurological deficits are typically due to some degree of neural compression by the tumor, and a direct decompression is often appropriate. Spinal stability is often tenuous due to the tumor, and may be further compromised during surgical decompression. Spinal instrumentation is therefore often used as an adjunct to decompression for spinal metastases with neurological symptoms.

Another common indication for spinal instrumentation in metastatic disease is spinal instability in the neurologically intact patient, which often leads to severe pain that limits mobility and may ultimately result in neurological deterioration if deformity is progressive. Spinal stabilization is often performed as a preliminary step, followed by chemotherapy and/or radiation therapy, depending on the characteristics of the primary tumor.

In both of these situations, surgical stabilization has historically been performed in a conventional open fashion. Wound complications, especially infection, are relatively common due to many factors, including the often malnourished state of cancer patients and the inability to medically optimize patients as can be done with elective surgery. Infection is potentially devastating, because chemotherapy 18

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and radiation therapy cannot be initiated until the wound has healed, or else it will probably never heal.

Spine surgeons are increasingly turning to percutaneous pedicle screw and rod stabilization in an effort to minimize the physiological burden of surgery, decrease the wound complication rate, and allow for early initiation of adjunctive therapy.

The findings generally support the use of percutaneous stabilization in the oncology patient, with the main advantages compared to open techniques being decreased blood loss, a lower infection rate, and an earlier initiation of chemotherapy and radiation therapy.

Though these are generalizations, many patients presenting with spinal metastases are elderly and have compromised bone quality. Metastases may involve multiple levels.

Instrumentation is therefore often performed over long segments, such as 2 or 3 levels above and below the main symptomatic lesion.

Cement is commonly used to augment screw fixation. If a direct decompression is necessary, this can sometimes be accomplished with an anterior or lateral approach, and then there is not a compelling reason to do an open posterior approach for stabilization, provided

the patient’s anatomy is conducive to percutaneous instrumentation.

Similarly, if a posterior approach is chosen for the decompression, this can often be limited to a relatively small open incision, followed by percutaneous instrumentation.

This strategy minimizes muscle stripping. Cement augmentation can readily be performed with percutaneous instrumentation, and recently the FDA approved a fenestrated pedicle screw system that allows for cement injection through the screw itself.

The main argument against percutaneous stabilization centers on the concept of instrumentation without an adjunctive fusion, which is actually “off-label” per the FDA. The main goal of surgery is to decompress the neural elements when necessary and to provide sufficient spinal stabilization to allow for chemotherapy and/or radiation therapy. These medical therapies are what will extend the patient’s life or even be curative, so the surgeon should be focused on expeditiously moving the patient through the peri-operative period.

Whether or not a fusion is ultimately achieved is not so important. If the patient lives long enough for the spinal instrumentation to become symptomatic and require revision or removal, this is a victory in my mind.

There is an increasing body of literature supporting the use of percutaneous instrumentation

without an adjunctive fusion, mainly for the treatment of spinal trauma, but there are approximately a dozen recent reports specific to spinal metastases. It is difficult to perform a high level of evidence study in this patient population for many reasons, and the studies are either case series or case-control series with retrospective controls.

The findings generally support the use of percutaneous stabilization in the oncology patient, with the main advantages compared to open techniques being decreased blood loss, a lower infection rate, and an earlier initiation of chemotherapy and radiation therapy. Based on these reports and general spine surgery principles, percutaneous

instrumentation should be considered when stabilization is necessary in the patient presenting with spinal metastases.

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COMORBIDITIES

The History, Evolution, and Current Use of Comorbidity Indices in Spine Research and Clinical Care Nathaniel T. Ondeck, BS; Jonathan N. Grauer, MD Introduction As efforts targeted at expanding preventative medicine services improve, and as management strategies for already existing diseases become more advanced, patients are living longer with more chronic conditions. In fact, the number of Americans with multiple chronic conditions has been rising throughout the 2000s, with over a quarter of individuals thought to have at least two chronic medical diseases in 2010.1 These trends do not spare individuals with spine disorders.

Over the same time period, the mean age and number of comorbid diseases in patients undergoing both anterior cervical discectomy and fusion (ACDF) and posterior lumbar fusion (PLF) procedures increased.2,3 Comorbidity is broadly defined as the presence of more than 1 distinct condition in an individual.4 One conceptualization of the importance of the presence of multiple diseases, is that comorbidity is thought to be associated with biological dysfunction and decreased physiologic reserve.5 This phenomenon may be causally related to what has been characterized in the field of geriatrics as frailty.6

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In an attempt to quantify the impact of the number and type of distinct diseases on patients, comorbidity indices have been constructed. They provide a method to simplify the study of the totality of a patient’s health by creating a common scale in which every patient can be assigned a score.

Specific comorbidity scales One of the earliest formal attempts at creating a comorbidity index is the American Society of Anesthesiologists physical status classification system (ASA), first described in 1941.7 After undergoing a series of minor modifications, its current form asks the physician to assign the patient a score of 1-6 that reflects the physiological reserve that the individual possesses at the time of surgery.8 Briefly, a patient is assigned a score of 1 if they have no health disturbances, 2 if they have a mild systemic disease with no functional limitation, 3 if they have a severe systemic disease with definite functional limitation, 4 if they have a severe systemic disease that is a constant threat to life, 5 if they are not expected to survive 24 hours with or without the operation, and 6 if they are a brain-dead organ donor. Despite being assigned solely upon physician gestalt, elevated ASA scores have been demonstrated to be associated with a variety of adverse outcomes

following spine surgery, including general health adverse events and readmission.9,10 In an attempt to improve the generalizability of therapeutic trials through encouraging the inclusion of patients with additional diagnoses, the Charlson Comorbidity Index (CCI) was created in 1987. Its stated purpose is to provide a method to identify diseases that singly or in combination, alter the risk for short term mortality.11 Unlike ASA, the CCI is quite reproducible due to a formula that, in its original form, assigns a weighted score for the presence of 19 comorbid diseases.

A patient’s score is the summation of their individual points, where the presence of cerebrovascular disease, chronic pulmonary disease, congestive heart failure, connective tissue disease, dementia, diabetes, mild liver disease, history of myocardial infarction, peripheral vascular disease, and ulcer disease is assigned 1 point, the occurrence of any tumor, hemiplegia, diabetes with end organ damage, leukemia, lymphoma, and moderate/severe renal disease is assigned 2 points, the diagnosis of moderate/sever liver disease is assigned 3 points, and the presence of AIDS or a metastatic solid tumor is assigned 6 points. Similarly to ASA values, a patient’s CCI has been correlated with numerous adverse outcomes in spine surgery, including medical

complications, and hospital readmission.12-14 The evolution of large data has led to an explosion of dataset research in orthopaedics.15 Clinical registry datasets, such as the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP), can be limited in the breadth of patient variables they collect. This has led to the adjustments of already existing comorbidity indices. One example, the modified Charlson Comorbidity Index (mCCI), utilizes just 11 of the original 19 variables, yet still has been shown to be correlated with adverse outcomes after spine procedures.16,17 It utilizes the same scoring and summation system as CCI, but does not include the presence of connective tissue disease, dementia, diabetes without end organ damage, mild liver disease, ulcer disease, leukemia, lymphoma, and AIDS. The aforementioned comorbidity scores are just a sampling of the many that are used in the medical literature. Additional indices found in spine research include the Elixhauser Comorbidity Measure, Frailty Index, Cumulative Illness Rating Scale, as well as others.

Discussion As described, a variety of comorbidity scores have been associated with adverse outcomes after spine surgery. The implementation of these scales in the clinic for purposes such as patient education, the identification of patients requiring additional prophylactic measures, as well as potential reimbursement adjustment, is a work in progress.

Recent research has focused on the development of new and the validation of already existing models for the pre-operative prediction of adverse outcomes.18,19 One example of this is the ACS-NSQIP universal surgical risk calculator developed in 2013.20 This model utilizes the appropriate Current Procedural Terminology code, information regarding 20 preoperative patient characteristics (including ASA score and the presence/absence of specific comorbid conditions), as well as the surgeon’s impression of each patient’s risk, to predict the occurrence of 10 adverse outcomes and hospital length of stay. While validation of this model in spine surgery is still ongoing, the concept of using comorbid diseases in pre-operative discrimination of patients who will or will not experience an adverse outcome will surely be a continuing research focus.

As we enter a period of medicine characterized by rising patient expectations, rigorous quality improvement programs, and changing outcome-based reimbursements, the implementation of an efficient and clinically proven method of predicting the occurrence adverse outcomes is surely valuable. Identifying patients who are likely to experience a complication will help set appropriate expectations for the patient, assist in guiding the use of additional prophylactic measures for the health care provider, and may be used to adjust bundled reimbursements. Much of this task relies upon correctly identifying and accurately weighing the presence of comorbid diseases. While further investigation is necessary, assessing patient disease through comorbidity scores will certainly continue to play an important role.

References 1. Ward BW, Schiller JS. Prevalence of multiple chronic conditions among US adults: estimates from the National Health Interview Survey, 2010. Preventing chronic disease. Apr 25 2013;10:E65.

2. Oglesby M, Fineberg SJ, Patel AA, Pelton MA, Singh K. Epidemiological trends in cervical spine surgery for degenerative diseases between 2002 and 2009. Spine. Jun 15 2013;38(14):1226-1232.

3. Pumberger M, Chiu YL, Ma Y, Girardi FP, Mazumdar M, Memtsoudis SG. National in-hospital morbidity and mortality trends after lumbar fusion surgery between 1998 and 2008.

The Journal of bone and joint surgery. British volume. Mar 2012;94(3):359-364.

4. Valderas JM, Starfield B, Sibbald B, Salisbury C, Roland M. Defining comorbidity: implications for understanding health and health services. Annals of family medicine. Jul-Aug 2009;7(4):357-363.

5. Karlamangla A, Tinetti M, Guralnik J, Studenski S, Wetle T, Reuben D. Comorbidity in older adults: nosology of impairment, diseases, and conditions. The journals of gerontology.

Series A, Biological sciences and medical sciences. Mar 2007;62(3):296-300.

6. Fried LP, Ferrucci L, Darer J, Williamson JD, Anderson G. Untangling the concepts of disability, frailty, and comorbidity: implications for improved targeting and care. The journals of gerontology. Series A, Biological sciences and medical sciences. Mar 2004;59(3):255-263.

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