Vertebral Columns, Summer 2022

Stem Cells in Degenerative Disc Disease

COLUMNS

Upper Cervical Spine Fractures The Future of Intraoperative Imaging in Spine Surgery Medicolegal Corner: What Spine Surgeons Should Know About Their Malpractice Policy Endoscopic Posterior Cervical Foraminotomy

International Society for the Advancement of Spine Surgery

PLUS

SHIFT IN USAGE OF

Ambulatory Surgical Centers FOR SPINE SURGERY

SUMMER 2022

Vertebral

INSIDE

Editor in Chief

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EDITORIAL

Kern Singh, MD

Shift in Usage of Ambulatory Surgical Centers for Spine Surgery

Editorial Board

BIOLOGICS

Brandon Hirsch, MD

Stem Cells in Degenerative Disc Disease

Sravisht Iyer, MD

TRAUMA

Yu-Po Lee, MD

Upper Cervical Spine Fractures

Sheeraz Qureshi, MD, MBA

LOOKING FORWARD The Future of Intraoperative Imaging in Spine Surgery

BUSINESS

Managing Editor Audrey Lusher Designer CavedwellerStudio.com

Medicolegal Corner: What Spine Surgeons Should Know About Their Malpractice Policy

ENDOSCOPY Endoscopic Posterior Cervical Foraminotomy: Stealth Surgery for the Treatment of Cervical Radiculopathy

Become a member today https://www.isass.org/about/membership/

Spring 2022

Peter Derman, MD, MBA

Vertebral Columns

Vertebral Columns is published quarterly by the International Society for the Advancement of Spine Surgery. ©2022 ISASS. All rights reserved.

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

This publication is available digitally at www.isass.org/news/vertebralcolumns-Summer-2022

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From the Department of Orthopedic Surgery, Rush University Medical Center, 1611 W Harrison St, Chicago, Illinois.

EDITORIAL

Shift in Usage of Ambulatory Surgical Centers for Spine Surgery In 2018, more than 23 million surgeries were performed in an ambulatory surgical center (ASC) in the United States. 1,2 Many of t hese surgeries consisted of cataract, arthroscopic, peripheral nerve, or soft tissue cases.1–3 In comparison to these other procedures, spine surgery has historically comprised a smaller proportion of ambulatory procedures. 3 However, with an estimated cost of $90 billion per year in the diagnosis and management of low back pain, performing spine surgery safely in the ASC has become an increasingly promising method of cost reduction.3,4 During the previous 2 decades, anterior cervical discectomy and fusion (ACDF), lumbar decompression, and single-level lumbar fusion comprised the majority of ASC-based spine procedures.5–7 Advancements in minimally invasive techniques have permitted more complex procedures in the ASC setting, such as multilevel lumbar fusion and 3-level ACDF. 5 Adoption of nonfusion techniques, such as cer vical disc replacement (CDR), have also introduced new types of procedures performed in the ASC.5

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This article examines the emergence of patient selection criteria in ambulatory spine surgery, ASC-based cervical and lumbar procedures, postoperative pain management, and future directions of performing spine surgery in the ASC.

Patient Selection Patient selection remains essential in minimizing risk of poor outcomes and complications in the ASC. One study of 708 patients eligible for outpatient spine surgery proposed patient selection criteria for performing spine surgery in the ASC. 8 These criteria considered proximity of 30 minutes to a hospital, body mass index (BMI) <42 kg/m 2 , medical clearance in patients with chronic conditions, clearance from a cardiologist in patients with heart disease, ability for a caretaker to be present for at least 24 hours after surgery, and an American Society of Anesthesiologists (ASA) classification of less than or equal to 3. 8 A separate study utilized a Delphi panel to determine safe patient selection in performing ACDF and CDR in the

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James W. Nie, BS

Timothy J. Hartman, BS

Keith R. MacGregor, BS

Omolabake O. Oyetayo, BS

Eileen Zheng, BS

Kern Singh, MD

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EDITORIAL

increased surgical invasiveness, and spinal deformity.10 The criteria proposed and Delphi panel indicate the biopsychosocial factors, comorbidities, and operative factors that must be considered when selecting patients for the ambulatory setting.

ASC.9 Here, the panel consensus determined that patients with severe cardiopulmonary comorbidities of a New York Heart Association class of III-IV, myocardial infarction within 6 months, severe angina, and/or ASA classification of 4 should preclude patients from undergoing surgery at an ASC.9 The senior author’s (K.S.) patient selection criteria considers similar factors.10 Specifically, age older than 65 years, BMI >40 kg/ m2, elevated risk of postoperative nausea and vomiting, functional dependence, inaccessibility of a reliable caregiver at home, and presence of severe medical comorbidities (eg, congestive heart failure, myocardial infarction within 6 months, angina, ASA ≥3, elevated risk of thromboembolism, or obstructive sleep apnea) are factors that preclude patients undergoing surgery in the ASC.10 Operative considerations that may preclude patients from undergoing surgery in the ASC include operative duration greater than 2 hours,

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Cervical Surgery From 1994 to 2006, ACDF comprised 5% to 17% of all spine cases performed in the ASC.7 In 2014, 30% of ACDF procedures were performed in the outpatient setting.11 Multiple studies have compared the safety profile and clinical outcomes of patients undergoing ambulator y versus hospital ACDF. Most of these studies concluded that performing outpatient ACDF is safe and has similar clinical outcomes compared to the hospital setting.3,12–17 However, these studies noted that patients should be observed 4-6 hours postoperatively to monitor for neck hematoma and airway compromise. 3,16 With the adoption of nonfusion techniques over the past 2 decades, CDR has become an alternative procedure in treating discogenic pathologies of the cervical spine.18 In articles comparing CDR versus ACDF, multiple studies reported that patients undergoing CDR demonstrated similar to superior clinical outcomes of pain, physical function, and disability.18–21 Furthermore, patients undergoing CDR had preserved range of motion, decreased adjacent segment disease, and decreased dysphagia, and they were less likely to undergo further surgery.18 In the outpatient setting, one study of 26 patients undergoing CDR in the ASC reported no complications or readmissions.22 A separate

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EDITORIAL

retrospective cohort study of 55 patients comparing single-level CDR against ACDF in the ASC reported no serious complications within 90 days of surgery, no incidence of hematoma formation, and significantly improved clinical outcomes. 23 Although current review of the literature for CDR in the ASC remains limited, the benefits of CDR along with initial safety assessments suggest increasing adoption of this surgical technique in the ASC.

Lumbar Fusion In the lumbar spine, lumbar decompression was one of the earliest procedures transitioned to the ambulatory setting and remains the most common spine procedure performed in the ASC. 3,5 Prior studies have consistently demonstrated favorable clinical outcomes and safety profile in patients undergoing lumbar decompression in the ASC. 3,5,24–27 The introduction of minimally invasive surgical techniques has increased the utilization and viability of performing ASC-based lumbar fusion.3,5 First introduced in the early 2000s, the minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) represents 1 minimally invasive technique performed in the ASC.28,29 In comparison to the open approach, patients undergoing MIS-TLIF had less postoperative pain, decreased postoperative narcotic usage, lower estimated blood loss, and shorter length of stay. 30–32 In addition, the lateral lumbar interbody fusion (LLIF) represents a different minimally invasive technique that has been performed in the outpatient setting. 33,34 Several articles examining MIS-

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“Consideration of the patient’s comorbidities and support system and the operative complexity must be considered prior to intervention.”

TLIF and LLIF in the ASC reported that these lumbar fusion procedures may be performed safely in the ambulatory setting and demonstrate favorable clinical outcomes. 5,10,33,34 Despite the limited number of studies, performing lumbar fusion in the ASC has become increasingly feasible.

Looking Forward A lt houg h per for m ing spine su rger y in t he A S C i s prom i s i ng a s a n ef fe c t i ve cost-reduction strateg y and a method of improving value-based care, consideration of the patient’s comorbidities and support s y stem a nd t he oper at ive c omple x it y must be considered prior to intervention.

Adv a ncement s i n m i n i ma l ly i nv a sive tech n iques a nd non f usion tech n iques have shifted the landscape of ASC-based spine surger y to involve more complex procedures and to introduce alternative su r g ic a l i nter vent ion s. A s add it iona l studies continue to conf irm the safet y, efficacy, and decreased economic burden of t hese procedures in t he hands of an ex perienced spine surgeon, t he ambulator y setting will likely continue to see an increase in the frequency of common cervical and lumbar procedures. n

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References 1. Young S, Pollard RJ, Shapiro FE. Pushing the envelope: new patients, pzrocedures, and personal protective equipment in the ambulatory surgical center for the COVID-19 Era. Adv Anesth. 2021;39:97–112.

2. Hall MJ, Schwartzman A, Zhang J, Liu X. Ambulatory surgery data from hospitals and ambulatory surgery centers: United States, 2010. Natl Health Stat Report. 2017;1–15.

3. Pendharkar AV, Shahin MN, Ho AL, et al.

Outpatient spine surgery: defining the outcomes, value, and barriers to implementation. Neurosurg Focus. 2018;44:E11.

4. Martin BI, Deyo RA, Mirza SK, et al.

Expenditures and health status among adults with back and neck problems. JAMA. 2008;299:656–664.

5. Gerling MC, Hale SD, White-Dzuro C, et al. Ambulatory spine surgery. J Spine Surg. 2019;5:S147–S153.

6. Gray DT, Deyo RA, Kreuter W, et al. Population-based trends in volumes and rates of ambulatory lumbar spine surgery. Spine.

2006;31:1957–1963, discussion 1964.

7. Best MJ, Buller LT, Eismont FJ. National trends in ambulatory surgery for intervertebral disc disorders and spinal stenosis: a 12-year analysis of the National Surveys of Ambulatory Surgery. Spine. 2015;40:1703–1711.

8. Chin KR, Pencle FJR, Coombs AV, Packer CF, Hothem EA, Seale JA. Eligibility of outpatient spine surgery candidates in a single private practice. Clin Spine Surg. 2017;30:E1352–E1358.

9. Mohandas A, Summa C, Worthington WB, et al. Best practices for outpatient anterior cervical surgery: results from a Delphi Panel. Spine. 2017;42:E648–E659.

10. Parrish JM, et al. Outpatient minimally invasive lumbar fusion using multimodal analgesic management in the ambulatory surgery setting. Int J Spine Surg. 2020;14:970–981.

11. 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:E1429–E1436.

12. Walid MS, Robinson JS 3rd, Robinson ERM, Brannick BB, Ajjan M, Robinson JS Jr. Comparison of outpatient and inpatient spine surgery patients with regards to obesity, comorbidities and readmission for infection. J Clin Neurosci. 2010;17:1497–1498.

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13. Silvers HR, Lewis PJ, Suddaby LS, Asch HL, Clabeaux DE, Blumenson LE. Day surgery for cervical microdiscectomy: is it safe and effective? J Spinal Disord. 1996;9:287–293.

14. Trahan J, Abramova MV, Richter EO, Steck JC. Feasibility of anterior cervical discectomy and fusion as an outpatient procedure. World Neurosurg. 2011;75:145–148.

15. Lied B, Rønning PA, Halvorsen CM, Ekseth K, Helseth E. Outpatient anterior cervical discectomy and fusion for cervical disk disease: a prospective consecutive series of 96 patients.

Acta Neurol Scand. 2013;127:31–37.

16. Lied B, Sundseth J, Helseth E. Immediate (0-6 h), early (6-72 h) and late (>72 h) complications after anterior cervical discectomy with fusion for cervical disc degeneration; discharge six hours after operation is feasible. Acta Neurochir. 2018;150:111–118.

17. Sheperd CS, Young WF. Instrumented outpatient anterior cervical discectomy and fusion: is it safe? Int Surg. 2021;97:86–89.

18. Findlay C, Ayis S, Demetriades AK. Total disc replacement versus anterior cervical discectomy and fusion: a systematic review with meta-analysis of data from a total of 3160 patients across 14 randomized controlled trials with both shortand medium- to long-term outcomes.

Bone Joint J. 2018;100-B:991–1001.

19. Janssen ME, Zigler JE, Spivak JM, Delamarter RB, Darden BV 2nd, Kopjar B. ProDisc-C total disc replacement versus anterior cervical discectomy and fusion for single-level symptomatic cervical disc disease: seven-year follow-up of the prospective randomized U.S. Food and Drug Administration Investigational Device Exemption study. J Bone Joint Surg Am. 2015;97:1738–1747.

20. Zigler JE, Delamarter R, Murrey D, Spivak J, Janssen M. ProDisc-C and anterior cervical discectomy and fusion as surgical treatment for single-level cervical symptomatic degenerative disc disease: five-year results of a Food and Drug Administration study. Spine. 2013;38:203–209.

21. Delamarter RB, Murrey D, Janssen ME, et al. Results at 24 months from the prospective, randomized, multicenter Investigational Device Exemption trial of ProDisc-C versus anterior cervical discectomy and fusion with 4-year follow-up and continued access patients. SAS J. 2010;4:122–128.

22. Wohns R. Safety and cost-effectiveness of outpatient cervical disc arthroplasty. Surg Neurol Int. 2010;1:77.

23. Chin KR, Pencle FJR, Seale JA, Pencle FK. Clinical outcomes of outpatient cervical total disc replacement compared with outpatient anterior cervical discectomy and fusion. Spine. 2017;42:E567–E574.

24. Helseth Ø, Lied B, Halvorsen CM, Ekseth K, Helseth E. Outpatient cervical and lumbar spine surgery is feasible and safe: a consecutive single center series of 1449 patients. Neurosurgery.

2015;76:728–737; discussion 737–738.

25. Best NM, Sasso RC. Success and safety in outpatient microlumbar discectomy. J Spinal Disord Tech. 2006;19:334–337.

26. Asch HL, Lewis PJ, Moreland DB, et al.

Prospective multiple outcomes study of outpatient lumbar microdiscectomy: should 75 to 80% success rates be the norm? J Neurosurg. 2002;96:34–44.

27. Pugely AJ, Martin CT, Gao Y, Mendoza-Lattes SA. Outpatient surgery reduces short-term complications in lumbar discectomy: an analysis of 4310 patients from the ACS-NSQIP database. Spine. 2013;38:264–271.

28. Foley KT, Lefkowitz MA. Advances in minimally invasive spine surgery.

Clin Neurosurg. 2002;49:499–517.

29. Basques BA, Ferguson J, Kunze KN, Phillips FM. Lumbar spinal fusion in the outpatient setting: an update on management, surgical approaches and planning.

J Spine Surg. 2019;5:S174–S180.

30. Hammad A, Wirries A, Ardeshiri A, Nikiforov O, Geiger F. Open versus minimally invasive TLIF: literature review and meta-analysis. J Orthop Surg Res. 2019;14:229.

31. Kim CH, Easley K, Lee JS, et al. Comparison of minimally invasive versus open transforaminal interbody lumbar fusion.

Global Spine J. 2020;10:143S–150S. 32. Qin R, Wu T, Liu H, Zhou B, Zhou P, Zhang X. Minimally invasive versus traditional open transforaminal lumbar interbody fusion for the treatment of low-grade degenerative spondylolisthesis: a retrospective study. Sci Rep. 2020;10: 21851.

33. Smith WD, Wohns RNW, Christian G, Rodgers EJ, Rodgers WB. Outpatient minimally invasive lumbar interbody: fusion predictive factors and clinical results.

Spine. 2016;41 (suppl 8):S106–S122.

34. Chin KR, Pencle FJR, Coombs AV, et al.

Lateral lumbar interbody fusion in ambulatory surgery centers: patient selection and outcome measures compared with an inhospital cohort. Spine. 2016;41:686–692.

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From the Hospital for Special Surgery (Mr Subramanian, Mr Zhao, and Dr Iyer) and the Weill Cornell Medical College (Mr Subramanian and Mr Zhao), both in New York, New York. All authors contributed equally to this article.

BIOLOGICS

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Stem Cells in Degenerative Disc Disease Degenerative disc disease (DDD) is one of the more common causes of chronic low back pain, disc herniation, spinal stenosis, and paresthesia. In fact, more than 90% of adults aged 50 years old and up have disc degeneration,1 often resulting in a significant decrease in quality of life. Current treatments for DDD include either conservative or surgical approaches, both of which aid in relieving the symptoms of ongoing disc degeneration. Intervertebral discs are complicated structures, and disc degeneration is usually a multifactorial process that may involve many different aspects of the disc. Because these current approaches fail to treat the underlying degenerative etiology, the clinical outcomes can vary. Biological approaches to the treatment of DDD have therefore become a field of increasing interest. Therapies including platelet-rich plasma, protein injections, gene therapies, and stem cells have all been researched to varying clinical success.2 Stem cells are undifferentiated and therefore can mature into a variety of specialized cells.

Because of the vast possibilities, employing stem cell therapy (SCT) has become one of the fastest emerging fields in medicine. Mesenchymal stem cells (MSCs) are a subset of nonhematopoietic stem cells that can be found in bone marrow and adipose tissue. These cells can differentiate into a variety of cells within the mesenchymal lineage, including chondrocytes, adipocytes, and osteoblasts.

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Because of the variety of terminal differentiation pathways for these cells as well as the relative ease of extraction, culture, and use, MSCs have become very popular therapeutic tools.3 Within the realm of degenerative spinal pathologies, these therapies hold great promise in treatment, whereas current treatment modalities remain mostly ineffective. In this review we discuss both the basic science and clinical literature in SCT for the treatment of DDD.

Tejas Subramanian, BE

Eric Zhao, BS

Basic Science Findings Sravisht Iyer, MD The therapeutic potential of MSCs in DDD comes from the differentiation into cells with the ability to proliferate within intervertebral discs, increase extracellular matrix (ECM) remodeling, and inhibit inflammation. In the basic science literature, cell and animal models have shown very promising results. Yang et al studied MSCs’ ability to arrest disc degeneration in a mouse model.4 The stem cells underwent chondrocytic differentiation within the disc and increased autonomous differentiation of notochordal cells, resulting in regeneration of the nucleus pulposus (NP) with upregulation of extracellular matrix promoting factors.4 In a rat model, Ekram et al found that MSCs differentiated into functional NP cells, which

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The basic science literature across medicine is ripe with promising results for the use of MSCs in the treatment of pathologies. We have described just some of these results for the treatment of DDD in animal models. However, there has generally been a slow adoption of these therapies in clinical practice. In the next section we will look at the preliminary clinical results utilizing MSC therapy for treatment of DDD in humans. also downregulated various pain and inflammation genes.5 Wang et al investigated one of the therapeutic mechanisms.6 Certain aberrant miRNA pathways have been implicated in disc degeneration and NP cell apoptosis.6 They found that MSCs upregulate and activate the miR-101-3p/EIF4G2 axis, thereby promoting ECM remodeling and repair in degenerated discs.6 Biglycan is another important component of the ECM; when it is deficient, it has been shown to lead to the progression of degenerative discs.7 Marfia et al found that by implanting MSCs into degenerative discs of biglycan-deficient mice, disc damage was improved and biglycan expression was increased.7 Studies have also analyzed pain and “clinical” outcomes in animal models utilizing stem cells for treatment of DDD. In a study of 4 canines with DDD presenting with chronic spinal cord injury, Penha et al treated them with MSCs.8 Each of the dogs demonstrated symptomatic improvements over time.8 Within 10 days after the procedure, they experienced recovery of the panniculus reflex and decreased pain response.8 By 18 months, the researchers observed significant clinical improvements, including improved movement.8

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Preliminary Clinical Results Despite its gradual onset in clinical practice, applications of stem cell transplantation in treating DDD have shown promising results.

Treatment often involves the injection of either autologous or allogeneic stem cells into the symptomatic disc, which can be a less invasive alternative to surgery. In a study conducted

by Pettine et al, 26 patients were referred for surgical consultation but opted for autologous bone marrow MSC injections at either 1 or 2 affected levels. 9 Throughout the 12-month follow-up, no adverse events were reported, and 21 out of 26 patients demonstrated statistically significant improvements in pain and disability based on the visual analog scale (VAS) and the Oswestry Disability Index (ODI).9 In another study by Kumar et al, 10 chronic low back pain patients were followed for 12 months following disc injections of autologous adipose-derived MSCs. ODI, VAS, 36-Item Short Form Survey (SF-36), and magnetic resonance imaging (MRI) were used to track patient progress.10 At 6 months, 7 patients had achieved greater than 50% reductions in VAS and ODI, which was sustained through 12 months in 6 of the patients.10 Adipose MSCs

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BIOLOGICS

are also harvested via a less-invasive process compared to bone marrow MSCs, and they produce a larger number of viable cells.10 Additional considerations in SCT are the ability of the transplanted cells to survive over time and the long-term safety of transplanted stem cells. One study by Henriksson et al reported that stem cells were able to survive in a degenerated intervertebral disc environment 8 months after transplantation.11 These transplanted cells differentiated into chondrocyte-like cells and were dispersed throughout the disc.11 These cells also stimulated native disc cells to produce ECM components, which may contribute positively to the health of degenerated discs.11 Indeed, transplanted stem cells in the long term may continue to help with symptom reduction in DDD. In a pilot study of 33 patients with DDD conducted by Centeno et al, patients were followed for up to 6 years after receiving autologous bone marrow MSCs.12 Patient-reported outcomes were measured using net promoter score (NPS), modified single assessment numeric evaluation (SANE) rating, functional rating index (FRI), and intervertebral disc measurements.12 In addition to there being no serious adverse events, post-transplant NPS reductions at months 3, 36, 48, 60, and 72 were significant relative to baseline.12 Improvements in SANE scores and FRI were also noted at multiple time points, and 17 of the 20 patients who opted to undergo MRI experienced an average disc bulge reduction of 23%.12 Another similar study

by Elabd et al followed 5 patients with DDD for 4 to 6 years after treatment with autologous bone marrow MSCs.13 The authors found that all patients reported overall improvement

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based on quality-of-life questionnaires and improvements in strength and mobility in 4 out of 5 patients.13 Zero adverse events were reported during the treatment and follow-up period, and no neoplasms were noted based on MRI imaging.13 While the study reported positive outcomes, it is limited by its small sample size and lack of randomization.

In addition to autologous cell transplants, transplants of allogeneic stem cells and nucleus pulposus (NP) cells are also possible treatments for DDD. While studies of allogeneic stem cell transplants are less common, Noriega et al demonstrated that DDD patients who received allogeneic stem cell treatment experienced significant improvements in VAS and ODI at months 3, 6, and 12 that were not reported in the control group.14 The MSC-treated group also reported improvements in disc degeneration as measured by the Pfirrmann scale, while the control group experienced worsening disc degeneration.14 Transplantation of nucleus pulposus cells is also an option for treating DDD by reducing inflammation and producing proteoglycans and collagen—2 components of healthy disc tissue. Mochida et al found that when autologous NP cells are co-cultured with autologous bone marrow MSCs, the MSCs were able to increase the viability and proliferation of NP cells in vitro.15 Additionally, out of 9 patients with Pfirrmann’s grade III disc degeneration treated with NP cells previously co-cultured with MSCs, average low back pain scores and Japanese Orthopaedic Association (JOA) clinical symptom scores both improved, and no further worsening of disc health was noted in any patient during the 3-year follow-up period.15

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Additional Considerations Disc degeneration is a highly common occurrence with aging, and symptomatic disc degeneration can be a painful and debilitating cause of chronic low back pain. SCT has the potential to be an effective surgical adjuvant or nonsurgical treatment option for patients; however, safety and ethical factors must be taken into consideration. Though studies of MSC therapy have generally been safe, MSCs can still undergo malignant transformations when exposed to a tumor

microenvironment.16 Additionally, the field of SCT is saturated with ethical dilemmas, including—but not limited to—donation of biological tissue, use of different stem cell sources, and weighing of risks and balances of SCT, all of which must be careful navigated if SCT is to grow in impact.17 Overall, SCT has shown great promise in treating DDD, and while the studies mentioned above have shown encouraging results, larger randomized double-blind studies are needed to further explore this field of great potential. n

References 1. Cheung KMC, Karppinen J, Chan D, et al. Prevalence and pattern of lumbar magnetic resonance imaging changes in a population study of one thousand forty-three individuals. Spine. 2009;34(9):934940. doi:10.1097/ BRS.0b013e3181a01b3f 2. Moriguchi Y, Alimi M, Khair T, et al. Biological treatment approaches for degenerative disk disease: a literature review of in vivo animal and clinical data. Glob Spine J. 2016;6(5):497-518.

3. Minguell JJ, Erices A, Conget P. Mesenchymal stem cells.

Exp Biol Med Maywood NJ. 2001;226(6):507-520.

4. Yang F, Leung VY, Luk KD, Chan D, Cheung KM. Mesenchymal stem cells arrest intervertebral disc degeneration through chondrocytic differentiation and stimulation of endogenous cells. Mol Ther. 2009;17(11):1959-1966.

5. Ekram S, Khalid S, Bashir I, Salim A, Khan I. Human umbilical cord-derived mesenchymal stem cells and their chondroprogenitor derivatives reduced pain and inflammation signal-

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ing and promote regeneration in a rat intervertebral disc degeneration model. Mol Cell Biochem. 2021;476(8):3191-3205.

6. Wang Z, Ding X, Cao F, Zhang X, Wu J. Bone mesenchymal stem cells promote extracellular matrix remodeling of degenerated nucleus pulposus cells via the miR-101-3p/ EIF4G2 Axis. Front Bioeng Biotechnol. 2021;9:642502.

7. Marfia G, Campanella R, Navone SE, et al. Potential use of human adipose mesenchymal stromal cells for intervertebral disc regeneration: a preliminary study on biglycan-deficient murine model of chronic disc degeneration. Arthritis Res Ther. 2014;16(5):457.

8. Penha EM, Meira CS, Guimarães ET, et al. Use of autologous mesenchymal stem cells derived from bone marrow for the treatment of naturally injured spinal cord in dogs. Stem Cells Int. 2014;2014:437521.

9. Pettine KA, Murphy MB, Suzuki RK, Sand TT. Percutaneous injection of autologous bone marrow concentrate cells significantly reduces lumbar

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discogenic pain through 12 months. Stem Cells Dayt Ohio. 2015;33(1):146-156.

10. Kumar H, Ha DH, Lee EJ, et al.

Safety and tolerability of intradiscal implantation of combined autologous adipose-derived mesenchymal stem cells and hyaluronic acid in patients with chronic discogenic low back pain: 1-year follow-up of a phase I study. Stem Cell Res Ther. 2017;8(1):262.

11. Henriksson HB, Papadimitriou N, Hingert D, Baranto A, Lindahl A, Brisby H. The traceability of mesenchymal stromal cells after injection into degenerated discs in patients with low back pain. Stem Cells Dev. 2019;28(17):1203-1211.

12. Centeno C, Markle J, Dodson E, et al. Treatment of lumbar degenerative disc disease-associated radicular pain with culture-expanded autologous mesenchymal stem cells: a pilot study on safety and efficacy. J Transl Med. 2017;15(1):197.

13. Elabd C, Centeno CJ, Schultz JR, Lutz G, Ichim T, Silva FJ. Intra-discal injection of autologous, hypoxic cul-

tured bone marrow-derived mesenchymal stem cells in five patients with chronic lower back pain: a long-term safety and feasibility study.

J Transl Med. 2016;14:253.

14. Noriega DC, Ardura F, Hernández-Ramajo R, et al.

Intervertebral disc repair by allogeneic mesenchymal bone marrow cells: a randomized controlled trial. Transplantation. 2017;101(8):1945-1951.

15. Mochida J, Sakai D, Nakamura Y, Watanabe T, Yamamoto Y, Kato S. Intervertebral disc repair with activated nucleus pulposus cell transplantation: a three-year, prospective clinical study of its safety.

Eur Cell Mater. 2015;29:202212; discussion 212.

16. Zhang YM, Zhang ZM, Guan QL, et al. Co-culture with lung cancer A549 cells promotes the proliferation and migration of mesenchymal stem cells derived from bone marrow. Exp Ther Med. 2017;14(4):2983-2991.

17. Lo B, Parham L. Ethical issues in stem cell research. Endocr Rev. 2009;30(3):204-213.

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TRAUMA

From UCI Health in Orange County, California.

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Upper Cervical Spine Fractures The upper cer v ical spine has a unique anatomy to help provide the majority of the range of motion of the cervical spine. The upper cervical spine, which consists of the occiput to C3 bones and joints, provides more than half of the f lexion, extension, and rotation of the cer v ical spine.1 The bony anatomy of the upper cervical spine protects the spinal cord and the vertebral arter y in this transitional area between the skull and spine. To allow this motion, the upper cervical spine is dependent on ligamentous integrity for mechanical stability. As a result, the upper cervical spine is prone to injur y. Upper cer vical spine injuries are potentially devastating injuries that spine surgeons must understand in order to provide appropriate treatment.

This article will highlight the classifications and treatments for atlanto-occipital dislocation (AOD), occipital condyle fracture, atlas fractures, C2 fractures, and C2 pars interarticularis fractures (Hangman’s fracture).

Atlanto-Occipital Dislocations Atlanto-occipital dislocations are highly unstable, often fatal injuries arising from the osseoligamentous disruption of the major stabilizers of the atlanto-occipital joint. There is injury to the alar ligaments, the tectorial membrane, and the atlanto-occipital joint capsule. Treatment is

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surgical with occipital cervical inst r umentat ion and f usion, usually occipital-C1 or occipital-C2 posterior instrumented fixation. 2 Sohaib Hashmi, MD Occipital Condyle Fractures Occipital condyle fractures are uncommon injuries usually resulting from high-energy blunt trauma. They are considered a type of basilar skull fracture a nd ca n be seen a long w it h Yu-Po Lee, MD cra n iocer v ica l d issociat ion.

Treatment of isolated occipital condyle fractures is generally conservative, unless t here is craniocer v ical junction instability. The Anderson and Montesano classification is used for describing occipital condyle fractures based on morphological variation and is separated into three categories: type I fractures are described as impacted-type occipital condylar fractures with little to no displacement of fragments 3; type II fractures involve extension of the condylar fracture to the basilar skull without loss of ligamentous integrity 3; and type III fractures are classified as inferomedial av u lsion-t y pe inju r ies of t he occipita l condyle with potential loss of stability due to concomitant injury of the contralateral alar ligament and tectorial membrane. 3

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Atlas Fractures Atlas (C1) fractures are generally the result of high-energy trauma, such as from falls or motor vehicle accidents. The mechanism is generally due to hyperextension or axial loading.4 Isolated anterior or posterior Figure 1

arch fractures are the most common. Isolated burst fractures are the second most commonly seen C1 fracture. Neurological injury, while rare, may occur if the burst fracture expands into the spinal canal.

The treatment of C1 fractures is based on whether they occur in isolation or in combination with other cervical spine injuries.

Figure 2

Figure 3

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TRAUMA

Also, treatment is based on the integrity of the transverse ligament. Isolated atlas fractures without injury of the transverse ligament or bony avulsion of the transverse ligament can be treated with bracing. Surgical fixation is recommended if there is disruption of the transverse ligament or if instability is present.4 The type of surgical fixation is determined by the presence of any concurrent occipitocervical injuries.

There are several classification systems for atlas fractures. The Jefferson classification is the most commonly used scheme in the United States and is separated into four types: type 1 and 2 fractures involve isolated injury to the posterior or anterior arches, respectively; type 3 fractures are a combination of types 1 and 2, involving injury to both the anterior and posterior arches; and type 4 fractures are classified as either unilateral or bilateral injury to the lateral mass or masses of the C1 vertebra. 5,6 Treatment of atlas fractures is dependent on the stability of the atlantodens interval (ADI). An ADI interval <3 mm (<5 mm in children) is normal, 3-5 mm represents injur y to t he t ransverse ligament w it h intact alar and apical ligaments, and >5 mm represents injur y to the transverse l iga ment, a la r l iga ment, a nd tector ia l membrane.7 One additional measure of stabilit y is measuring the displacement of the C1 lateral masses, where a displacement >6.9 mm may indicate a transverse ligament injury. Treatment of stable type 1, 2, and 3 fractures includes use of a hard collar or halo immobilization for 6 to 12 weeks. For unstable type 2 and 3 fractures,

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treatment involves posterior C1-2 fusion or occipitocervical fusion.7

C2 Fractures First described in 1910 by Mixter and Osgood, fractures of the C2 dens, known as odontoid fractures, are typically the result of h ig h-energ y t rau ma to t he cer v ica l spine, resulting in forced hyperextension. 8 Common mechanisms of injur y include motor vehicle accidents, diving injuries, or falls from significant height in younger patients with high bone mineral density.

In older pat ients, lower energ y events, such as ground-level falls, may result in a similar pattern of injury. 8 Developed in 1974, Anderson and D’Alonzo developed a classif ication system of 3 t y pes of C2 fracture, described by increasing severity: • Type 1: avulsion fracture of the rostral tip of the odontoid • Type 2: fracture through the waist of the odontoid process • Type 3: fracture through the body of the C2 vertebrae Hard collar or halo immobilization is recommended for types 1 and 3 odontoid fractures. In patients with type 2 odontoid fractures, a hard collar is recommended in patients who are older than 80 years or who are poor surgical candidates. With hard collar management, patients risk development of a fibrous nonunion; however, not all of the fibrous nonunions will go on to develop a symptomatic nonunion. 9 A posterior C1-2 fusion is recommended for C2 fractures in patients who are able to undergo surgery or have late dysfunction.10

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C2 Pars Interarticularis Fracture (Hangman’s Fracture) Bilateral fracture of the pars interarticularis of C2 is commonly referred to as a Hangman’s fracture. These injuries are relatively common cervical spine fractures.

Several fracture classifications have been proposed. However, atypical Hangman’s fracture variants may cause spinal canal

compromise rather than canal expansion.

The at y pical Hangman’s variants often have coronal or sagittal plane fractures of t he posterior body of t he dens. This fragment may cause neurological deficits with this injury (Figure 1).11 A summary of the Levine and Edwards classification and management of Hangman’s fracture is provided in the Table. n

Table. Levine and Edwards Classification and Management of Hangman’s Fracture Type

Description

Treatment

1

<3 mm subluxation of C2 on C3.

Conservative management with rigid cervical collar

2

Disruption of the C2 to C3 disc, >4 mm subluxation, greater than 11° angulation

<5 mm requires reduction and halo fixation for 6-12 weeks while >5 mm may require surgery

2a

Less displacement than type 2 but with more angular deformity

Treatment in a halo fixation or surgical management

3

C2 to C3 facet capsule disrupted, anterior longitudinal ligament also disrupted

Surgical treatment may be necessary; options include C2-3, anterior cervical discectomy and fusion, isolated C2 fixation, C1-2 posterior fusion, or C1-3 posterior fusion depending on integrity of the C2-3 disc and facets (Figures 2 and 3)

References 1. Whitcroft KL, Massouh L, Amirfeyz R, Bannister G. Comparison of methods of measuring active cervical range of motion. Spine. 2010;35:E976–E980.

2. Joaquim AF, Schroeder GD, Vaccaro AR. Traumatic atlanto-occipital dislocation-a comprehensive analysis of all case series found in the spinal trauma literature.

Int J Spine Surg. 2021;15:724–739.

al. Treatment of atlas fractures: recommendations of the Spine Section of the German Society for Orthopaedics and Trauma (DGOU). Global Spine J. 2018;8(2 suppl):5S–11S. 5. Landells CD, Van Peteghem PK. Fractures of the atlas: classification, treatment and morbidity. Spine. 1988;13:450–452.

3. Anderson PA, Montesano PX. Morphology and treatment of occipital condyle fractures. Spine. 1988;13:731–736.

6. Kontautas E, Ambrozaitis KV, Kalesinskas RJ, Spakauskas B. Management of acute traumatic atlas fractures. J Spinal Disord Tech. 2005;18:402–405.

4. Kandziora F, Scholz M, Pingel A, et

7. Kim D, Viswanathan VK, Menger RP. C1

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Fractures. StatPearls Publishing. 2022.

8. Pryputniewicz DM, Hadley MN. Axis fractures. Neurosurgery. 2010;66:68–82.

9. Tenny S, Varacallo M. Odontoid Fractures. StatPearls Publishing. 2022.

10. Hsu WK, Anderson PA. Odontoid fractures: update on management. J Am Acad Orthop Surg. 2010;18:383–394.

11. Murphy H, Schroeder GD, Shi WJ, et al. Management of Hangman’s fractures: a systematic review. J Orthop Trauma. 2017;31(suppl 4):S90–S95.

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From the Hospital for Special Surgery in New York, New York.

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The Future of Intraoperative Imaging in Spine Surgery Intraoperative imaging has played a vital role in spine surgery over the past several decades.1 The ability to objectively determine the amount of tissue removal, correctly position different implants, and assess the degree of deformity correction are only a few of the many advantages that imaging techniques have provided.

These techniques have ultimately allowed spine surgeons to track the position of surgical instruments, provide multiplanar views of the anatomy, and aid in preoperative planning.2 There is ongoing research to improve the intraoperative imaging modalities in spine surgery that can eventually improve patient outcomes.2 Spine surgeries have transitioned from the use of radiography, ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and fluoroscopy to various types of navigation and robotic systems.1,2 Yet, more recently, the use of machine-learning algorithms, augmented reality systems, and virtual reality systems are becoming more scrutinized and seem to be paving the way for future modalities.3 This article gives a brief overview of the possible future of intraoperative imaging in spine surgery.

Machine Learning Machine-learning algorithms are codes created in an artificial intelligence (AI) computer program that can perform various tasks based on any data provided by an investigator.4 Numer-

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ous algorithms, which range from Robert Kamil, BS simply labeling vertebral levels on patients to AI-guided pedicle screw placement, have already been created.5 In 2017, one study created an AI capable of identifying vertebral levels and intervertebral discs in 96% to 97% of cases.6 In a separate Pratyush Shahi, MBBS, study, an algorithm was created MS (Ortho) capable of enhancing radiographic files for increased image resolution that was able to provide automatic conversion of various imaging modality files (eg, radiography to MRI and MRI to CT).7 Further studies demonstrated a pedicle Sheeraz A. Qureshi, MD, screw algorithm system that could MBA properly suggest screw entry points with 95.4% accuracy in patients undergoing corrective deformity surgery with Cobb angles less than 75%.8 Notably, their entire algorithm was able to create these projections at a mean of 11 seconds.8 These self-learning computers are of great interest in spine surgery because they can facilitate better surgical planning, aid in the prediction of postoperative alignment, and provide computerized consistency among treatments. Although the use of such tools continues to be time-consuming, as the amount of available data for these machine-learning algorithms increases, their capabilities will exponentially increase as well.9

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LOOKING FORWARD

Augmented Reality Augmented reality (AR) systems allow the projection of virtual 3-dimensional (3D) images onto a user’s real-time view of the surgical f ield. The current commercial prototypes that exist have improved the efficiency of instrumentation placement in fusion surgeries, increased patient safety outcomes, optimized ergonomics in the surgical suite, and ultimately lowered various procedural costs.10 Current published literature on AR-guided navigation for spine surgery has explored the application of AR for pedicle screw fixation, anterior cervical discectomy and fusion (ACDF) procedures, and spinal deformity cases with promising results.10,11 A recent prospective clinical trial of 20 patients undergoing AR-guided spinal fixation reported an overall thoracic pedicle screw accuracy level of 94.1%. Another study reported that AR was helpful for ACDF and posterior cervical laminotomy and foraminotomy.12 Kosterhon et al utilized AR to visualize resection planes of an intraoperative osteotomy in a live spinal deformity patient to determine whether it could help increase accuracy and patient safety.13 Ultimately, the authors determined that surgeons benefitted from the display and were able to turn the display off if it was ever found to be too distracting. While AR prototype systems are still continuously being developed, their wide range of applications in spine surgery should certainly be anticipated in the coming years.

Virtual Reality Interactive feedback-based virtual reality (VR) systems have recently moved to the forefront of spine surgery. VR has been proven

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to aid with surgical training, preoperative planning, and complex spinal deformity cases. The main benefit of the VR concept is the opportunity to improve one’s surgical technique while minimizing the possibility of mistakes and often reducing costs. Gasco et al compared the performance of a group of medical students utilizing traditional visual and verbal instructions for lumbar pedicle screw placements in sawbones with another group of medical students utilizing a VR simulator for the same task. The study concluded that the simulation group outperformed the traditional learning group in all variables, including trajectory, depth of screw error, and breach.14 The results were attributed to sequential learning, enhanced depth perception, and increased 3D anatomical understanding.14 Similarly, Gottschalk et al provided further credence to the applicability of VR through a blinded, randomized controlled trial that examined whether VR helped orthopedic residents improve lateral mass screw insertion in the cervical spine of cadavers and sawbones.15 It was found that the residents significantly improved when previously trained with VR.15 Complementary to VR training, more recent efforts have tried expanding the uses of VR into the practice of experienced spine surgeons.16 Zhou et al combined VR with navigation for minimally invasive lumbar transforaminal microdiscectomy and had the same surgeon place L3–S1 screws on the left side of a cadaver without the use of VR and navigation, then had them do a VR simulation for surgical planning and place screws on the right side.17 The VR-planned side was

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found to have better exposure and puncture-to-channel times.17 Similarly, Zheng et al compared percutaneous endoscopic lumbar discectomies with and without preoperative VR planning for thirty randomized patients and found improved location timing when VR planning was used.18 Another study explored the use of VR for comparing preoperative and postoperative imaging of patients with adult spinal deformity.19 They demonstrated that the use of VR for 3D reconstruction greatly benefitted the assessment and decision-making processes.19 VR has demonstrated better preoperative planning in minimally invasive

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spinal procedures and should be anticipated to be in more spine training modules and complex spine cases in the near future.

Conclusion The future of intraoperative imaging in spine surgery is exciting. The clear applicability of machine-learning algorithms, AR prototypes, and VR-based simulators has been rapidly growing and has certainly shown very promising results. As research on these different prototypes continues to expand, their wide utilization should be expected to increase in the very near future. n

References reality head-mounted display: 6. Forsberg D, Sjöblom E, Sunshine 1. Qureshi S, Lu Y, McAnany S, a proof-of-concept study. NeuJL. Detection and labeling of Baird E. Three-dimensional rosurg Focus. 2021;51(2):E11. vertebrae in MR images using intraoperative imaging modaldeep learning with clinical annoities in orthopaedic surgery: a 11. Yoo JS, Patel DS, Hrynewycz tations as training data. J Digit narrative review. J Am Acad OrNM, Brundage TS, Singh K. Imaging. 2017;30(4):406-412. thop Surg. 2014;22(12):800-809.

The utility of virtual reality and augmented reality in 2. Nimsky C, Carl B. Historical, cur- 7. Galbusera F, Bassani T, Casaroli spine surgery. Ann Transl G, et al. Generative models: an rent, and future intraoperative Med. 2019;7(Suppl 5):S171. upcoming innovation in musimaging modalities. Neurosurg culoskeletal radiology? A preClin N Am. 2017;28(4):453-464.

12. Mascitelli JR, Schlachter L, liminary test in spine imaging.

Chartrain AG, et al. Naviga3. Yuk FJ, Maragkos GA, Sato K, Eur Radiol Exp. 2018;2(1):29. tion-linked heads-up display in Steinberger J. Current innovaintracranial surgery: early ex8. Burström G, Buerger C, Hoption in virtual and augmented perience. Oper Neurosurg (Hagpenbrouwers J, et al. Machine reality in spine surgery. Ann erstown). 2018;15(2):184-193. learning for automated 3-diTransl Med. 2021;9(1):94. mensional segmentation of the 13. Kosterhon M, Gutenberg A, Kan4. Bajwa A. Artificial intellispine and suggested placement telhardt SR, Archavlis E, Giese A. gence vs robotics vs machine of pedicle screws based on Navigation and image injection learning vs deep learning vs intraoperative cone-beam comfor control of bone removal data science. Medium. March puter tomography. J Neurosurg and osteotomy planes in spine 11, 2021. https://medium.

Spine. 2019;31(1):147-154. surgery. Oper Neurosurg (Hagdatadriveninvestor.com/ erstown). 2017;13(2):297-304.

9. Lafage R, Pesenti S, Lafage artificial-intelligence-vs-roV, Schwab FJ. Self-learning botics-vs-machine-learn14. Gasco J, Patel A, Ortega-Barnett computers for surgical planning ing-vs-deep-learning-vs-daJ, et al. Virtual reality spine and prediction of postoperta-science-70ff828cdf39 surgery simulation: an empirical ative alignment. Eur Spine J. study of its usefulness. Neurol 5. Harada GK, Siyaji ZK, Younis 2018;27(suppl 1):123-128.

Res. 2014;36(11):968-973.

S, Louie PK, Samartzis D, An 10. Yanni DS, Ozgur BM, Louis HS. Imaging in spine surgery: 15. Gottschalk MB, Yoon ST, Park RG, et al. Real-time navigation current concepts and future DK, Rhee JM, Mitchell PM. Surgiguidance with intraoperative directions. Spine Surg Relat cal training using three-dimenCT imaging for pedicle screw Res. 2019;4(2):99-110. sional simulation in placement placement using an augmented

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of cervical lateral mass screws: a blinded randomized control trial. Spine J. 2015;15(1):168-175.

16. Yuk FJ, Maragkos GA, Sato K, Steinberger J. Current innovation in virtual and augmented reality in spine surgery. Ann Transl Med. 2021;9(1):94.

17. Zhou Z, Hu S, Zhao YZ, et al.

Feasibility of virtual reality combined with isocentric navigation in transforaminal percutaneous endoscopic discectomy: a cadaver study.

Orthop Surg. 2019;11(3):493-499.

18. Zheng C, Li J, Zeng G, et al.

Development of a virtual reality preoperative planning system for postlateral endoscopic lumbar discectomy surgery and its clinical application. World Neurosurg. 2019;123:e1-e8.

19. Lafage R, Bess S, Glassman S, et al. Virtual modeling of postoperative alignment after adult spinal deformity surgery helps predict associations between compensatory spinopelvic alignment changes, overcorrection, and proximal junctional kyphosis. Spine (Phila Pa 1976).

2017;42(19):E1119-E1125.

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BUSINESS

From The Core Institute in Mesa, Arizona.

Medicolegal Corner What Spine Surgeons Should Know About Their Malpractice Policy Malpractice claims are common occurrences for spine surgeons, with an estimated annual incidence between 14% and 19%.1 Despite the frequency of claims related to spine surgeons, verBrandon P. Hirsch, MD dicts in favor of the plaintiff are uncommon, with a 2018 analysis of the Westlaw database reporting that more than 71% of cases being decided in the defendant’s favor. 2 Although spine surgeons often prevail in malpractice litigation, settlements and plaintiff’s verdicts can involve large sums. A recent analysis of 103 cases found an average settlement amount of $2.4 million with an average plaintiff’s verdict of $3.9 million. 3 The frequency of claims and high dollar value of adverse judgments tend to make malpractice insurance costly for spine surgeons. In a 2012 study, 70% of respondents in a large survey reported that they spend more than 10% of their gross annual practice revenue on premiums.4 Despite its importance, most surgeons receive minimal education on the pertinent aspects of malpractice insurance during training. With the continued trend toward surgeon employment or its variants, many spine surgeons are now covered by policies that were chosen on their behalf by a larger entity, further limiting their familiarity with policy details.

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Professional liability insurance is generally structured as either an “occurrence” or a “claims-made” policy. Occurrence policies cover claims made for any event that occurred during the period that the policy was in effect, regardless of when a claim was filed.

Occurrence policies tend to have significantly higher premiums and have become uncommon. The majority of physician malpractice policies in effect today are “claims-made” policies. These policies will cover claims only if they are made during the period of coverage AND if the event pertaining to the claim also occurred during the time that the policy was in effect. Coverage under claimsmade policies may end at the termination of the policy or may include what is known as “tail-coverage” that covers claims for a set period of time after the policy ends. Surgeons who are changing practices (or insurance carriers) must be aware of how their policy is worded in this regard, as they will often be required to arrange their own “tail-coverage” or ensure that their new practice has arranged to provide this coverage.

The quantity of coverage offered in a liability policy is particularly important for spine surgeons to be aware of given the large dollar amounts typically associated with settlements and defense verdicts in the field.

Referred to as “policy limits,” these values are typically expressed as both a per-claim

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amount and an aggregate annual amount.

When settlements or verdicts exceed these thresholds, the insured are responsible for the remaining amount. Most carriers offer a standard limit of $1 million per claim and $3 million aggregate annual coverage. In some scenarios, it may be advantageous for spine surgeons to have higher policy limits. Many factors, some of which are state-specific, can affect this decision. Surgeons should consult with a knowledgeable insurance agent or experienced colleague when determining how much coverage to obtain. It is also important to understand whether legal fees are considered “inside” or “outside” the policy limits. When defense costs are considered inside the policy limits, they are included in the total coverage offered by the policy, reducing the amount the insurer will pay toward a settlement or defense verdict. Policies where defense costs apply outside the limits are advantageous in that they do not reduce coverage amounts due to legal fees.

It is also important to understand whether your policy provides the right to select your own counsel. Commonly, insurers assign attorneys on behalf of the insured. Cases involving spine surgery tend to involve multiple co-defendants (assistant, anesthesia, neuromonitoring technician/physician, employer, hospital), sometimes covered by the same insurance carrier. In these scenarios, co-defendants are often assigned the same firm or attorney to reduce cost to the carrier. In cases involving multiple co-defendants, conf licts of interest may exist in the representation of each party.

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Defense strategies that are advantageous to the hospital may not be advantageous to the surgeon. Such conflicts can be harmful to a defendant’s case and should always be avoided. While a clause specifying the right to select counsel ensures this right, it is not necessarily required in order to obtain independent representation. When a conflict of interest becomes evident, it is important to express this in writing, to both the attorney and the insurer. Attorneys are ethically bound to recuse themselves from representing a party when these conflicts exist. Failure to do so runs the risk of incurring additional liability for legal malpractice or being sanctioned by the state bar association.

Another important feature in a liability policy is a clause that protects the right to refuse settlement. In essence, this clause prevents the insurer from electing to settle the case

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“Due to the potential for large plaintiff’s judgements, spine surgeons should be aware of their policy limits and consider whether they are adequate. Clauses protecting the right to choose counsel and the right to refuse settlement can be very important components of a liability policy, particularly in cases involving multiple or corporate codefendants.”

without your consent. For many defendants, a settlement is preferable to proceeding to trial and risking a jury verdict that exceeds policy limits. While settlements may not involve financial cost to the defendant, they can still have other untoward effects on a spine surgeon’s career. The National Practitioner Data Bank (NPDB) is a federal online database of adverse actions taken against healthcare professionals. The database contains state medical board complaints, sanctions levied by professional societies, licensure revocation or restriction, and all

plaintiff’s judgments and malpractice settlements on a physician’s behalf. While an individual listing in the database may not be problematic, multiple occurrences can affect a physician’s ability to obtain future employment and/or professional liability coverage. Preserving the right to refuse settlement allows the surgeon to control whether or not their case will appear in the NPDB, which in many cases is more valuable than the outcome of the claim itself.

Malpractice liability in spine surgery is a complex and constantly evolving topic. A basic understanding of liability policy structure and content is useful to all spine surgeons, perhaps more so than physicians in any other specialty. Due to the potential for large plaintiff’s judgements, spine surgeons should be aware of their policy limits and consider whether they are adequate. Clauses protecting the right to choose counsel and the right to refuse settlement can be very important components of a liability policy, particularly in cases involving multiple or corporate co-defendants. Spine surgeons can save tremendous cost, frustration, and potential reputational harm by taking the time to investigate these aspects of a policy in advance of encountering a malpractice claim. n

References 1. Jena AB, Seabury S, Lakdawalla D, et al. Malpractice risk according to physician specialty. N Engl J Med. 2011;365:629–636.

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2. Agarwal N, Gupta R, Agarwal P, et al. Descriptive analysis of state and federal spine surgery malpractice litigation in the United States. Spine (Phila Pa 1976). 2018;43:984–990.

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3. Makhni MC, Park PJ, Jimenez J, et al. The medicolegal landscape of spine surgery: how do surgeons fare?

Spine J. 2018;18:209–215.

4. Nahed BV, Babu MA, Smith TR, et al. Malpractice liability and defensive medicine: a national survey of neurosurgeons. PLoS One. 2012;7:e39237.

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From the Texas Back Institute in Plano, Texas.

ENDOSCOPY

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Endoscopic Posterior Cervical Foraminotomy Stealth Surgery for the Treatment of Cervical Radiculopathy Posterior cervical foraminotomy (PCF) with or without discectomy is a well-established treatment for cervical radiculopathy. Unlike anterior cervical discectomy and fusion (ACDF), the traditional gold standard surgical treatment, PCF allows for nerve root decompression without the need for instrumentation and without sacrificing motion. It has been studied extensively and has been found to have clinical outcomes that are generally comparable to ACDF.1–3 One barrier to the more widespread utilization of PCF may be the increased muscle spasm, neck pain, and blood loss associated with open posterior approaches to the cervical spine.4,5 However, the development of less invasive techniques has decreased approach-related morbidity and made PCF a more appealing option than it had been in the past. Minimally invasive tubular approaches produce similar degrees of symptomatic relief to open foraminotomy but with less blood loss, immediate postoperative neck pain, analgesic use, and hospital length of stay.6,7 Endoscopic techniques allow surgeons to perform PCF in an even more atraumatic fashion. As might be expected, full-endoscopic PCF produces shorter hospital stays and less postoperat ive neck pain than other techniques without sacrificing clinical effectiveness. 8,9 The benefit of the

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endoscopic approach extends beyond si mply preser vat ion of the paraspinal soft tissues, however. The angled optics of the endoscope facilitate viewing deeper w it hin t he foraminal Peter B. Derman, MD, space, and the narrow endoscopMBA ic cannula can be directed in a more medial-to-lateral trajectory before abutting the spinous process than can a conventional tubular retractor. Both of these features permit more extensive undercutting of the facet joint, which allows for adequate expansion of the foraminal area while minimizing the degree of facet joint resection and may reduce the incidence of postoperative segmental hypermobility. 8 The surgical indications for endoscopic PCF are identical to those established for open or tubular approaches: foraminal stenosis due to disc herniation and/or osseous overgrowth in the absence of significant central stenosis, instability, or deformity.4 The operative technique is likewise similar to open or tubular PCF. My technique is briefly described as follows: • The patient is positioned prone on a Jackson frame with the head resting on a foam head holder and the arms down by the patient’s sides. Cranial traction is not employed.

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ENDOSCOPY

• After fluoroscopic localization and infiltration of local anesthetic, an 8-mm longitudinal paramedian skin and fascial incision is made overlying the laminar facet junction on the side of the approach in line with the disc space at the operative level.

• Sequential dilators, followed by the working cannula and endoscope, are inserted.

• The medial border of the facet joint (known as the “interlaminar V”) is identified.

• A burr and Kerrison rongeur are used to complete the dorsal decompression as they would be open—the medial approximately one-third of the inferior and superior

articular processes are resected, unroofing the foramen and revealing the exiting nerve root (Figure 1).

The superior articular process of the caudal vertebra can be undercut to further expand the foraminal dimensions without sacrificing an additional facet joint. Decompression should span from cranial to caudal pedicle and to the lateral margin of these pedicles.

• The disc space can be explored and herniated disc fragments removed with a micro-pituitary rongeur, if present.

Visualization during an endoscopic PCF tends to be excellent for a number of reasons. Modern endoscopic systems feature

Figure 1.

Intraoperative photograph looking medially toward the thecal sac during a left C6-7 endoscopic posterior cervical foraminotomy.

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ENDOSCOPY

high-definition optics and displays with crisp resolution. Additionally, the hydrostatic pressure afforded by the continual irrigation reduces bleeding from the venous plexus that can be problematic during an open or tubular PCF. Furthermore, the off-axis viewing angle of the endoscope allows the surgeon to see around corners and even turn and look laterally back out the foramen (Figure 2). The lateral aspects of the pedicles can be directly visualized as they slope away, confirming that decompression is complete.

Despite the benefits of endoscopic PCF, it is not an entry-level endoscopic procedure, as the cannula must remain safely docked on the dorsal osseous structures while instruments are carefully

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advanced into the canal and foramen. Failing to do so could result in neurologic injury.

This challenge is certainly surmountable as surgeons become more experienced and comfortable with endoscopic techniques in the lumbar spine. Once mastered, endoscopic PCF can become a valuable, ultra-minimally invasive tool for the treatment of cervical radiculopathy. l Figure 2. Intraoperative photograph looking laterally out the foramen during a left C6-7 endoscopic posterior cervical foraminotomy.

The endoscope is rotated 180° from its orientation in Figure 1 to achieve this view.

References 1. Guo L, Wang J, Zhao Z, et al. Microscopic anterior cervical discectomy and fusion versus posterior percutaneous endoscopic cervical keyhole foraminotomy for single-level unilateral cervical radiculopathy: a systematic review and meta-analysis [published online March 29, 2022]. Clin Spine Surg.

2. Liu WJ, Hu L, Chou PH, Wang JW, Kan WS. Comparison of anterior cervical discectomy and fusion versus posterior cervical foraminotomy in the treatment of cervical radiculopathy: a systematic review. Orthop Surg. 2016;8(4):425-431.

3. Sahai N, Changoor S, Dunn CJ, et al.

Minimally invasive posterior cervical foraminotomy as an alternative to anterior cervical discectomy and fusion

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for unilateral cervical radiculopathy: a systematic review and meta-analysis. Spine. 2019;44(24):1731-1739.

4. Bhatia S, Brooks NP. Posterior endoscopic cervical foraminotomy. Neurosurg Clin N Am. 2020;31(1):9-16.

5. Skovrlj B, Gologorsky Y, Haque R, Fessler RG, Qureshi SA. Complications, outcomes, and need for fusion after minimally invasive posterior cervical foraminotomy and microdiscectomy.

Spine J. 2014;14(10):2405-2411.

6. Kim KT, Kim YB. Comparison between open procedure and tubular retractor assisted procedure for cervical radiculopathy: results of a randomized controlled study.

J Korean Med Sci. 2009;24(4):649-653.

7. Winder MJ, Thomas KC. Minimally invasive versus open approach for cervical laminoforaminotomy. Can J Neurol Sci. 2011;38(2):262-267.

8. Kim JY, Hong HJ, Lee DC, Kim TH, Hwang JS, Park CK. Comparative analysis of 3 types of minimally invasive posterior cervical foraminotomy for foraminal stenosis, uniportal-, biportal endoscopy, and microsurgery: radiologic and midterm clinical outcomes.

Neurospine. 2022;19(1):212-223.

9. Tacconi L, Signorelli F, Giordan E. Cervical foraminotomy by full-endoscopic posterior cervical approach: a randomized study.

Interdiscip Neurosurg. 2021;26:101287.

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