Vertebral Columns Fall 2024

PLUS:

Fusion Assessment

Comparison in Cervical Fusion Surgery

Biologics in

Vertebral COLUMNS

International Society for the Advancement of Spine Surgery

EDITORIAL

Review of Topics Posted by Spine Surgeons on TikTok

CERVICAL SPINE

Fusion Assessment Comparison in Cervical Fusion Surgery

BIOLOGICS

Biologics in TLIF—A Focus on Cost and Efficacy

BONE HEALTH

Bone Quality Assessment in Spine Surgery

BONE HEALTH

Treatment for Osteoporosis

PATIENT OPTIMIZATION

Preoperative Malnutrition in Spine Surgery

TRAINING

Framework for Mentorship of Spine Surgeons in Early Practice

MEDICAL PRACTICE

Ambulatory Surgery Center Development in an Academic Medical Center—Is It Possible?

Fall 2024

Editor in Chief

Kern Singh, MD

Editorial Board

Peter Derman, MD, MBA

Brandon Hirsch, MD

Sravisht Iyer, MD

Yu-Po Lee, MD

Sheeraz Qureshi, MD, MBA

Managing Editor

Audrey Lusher

Designer CavedwellerStudio.com

Vertebral Columns is published quarterly by the International Society for the Advancement of Spine Surgery.

©2024 ISASS. All rights reserved. Opinions of authors and editors do not necessarily reflect positions taken by the Society.

This publication is available digitally at https://isass.org/category/news/ vertebral-columns/

From the Department of Orthopaedic Surgery at Rush University Medical Center in Chicago, Illinois.

Review of Topics Posted by Spine Surgeons on TikTok

Social media platforms like TikTok, once dominated by dance challenges and viral memes, are now becoming powerful tools for medical professionals to share knowledge, connect with patients, and engage with the global community. From viral surgical videos to patient success stories, spine surgeons are increasingly utilizing social media to share insights, build communities, and even learn from one another.

A 2023 review of social media use by 325 spine surgeons from 76 institutions across the United States found that 64.6% had at least one professional social media account.1 The majority (57.2%) had a LinkedIn account. Unsurprisingly, the review also found that surgeon age, years in practice, and practice type correlated with social media activity. Similarly, a 2023 survey of French spine surgeons revealed that 80% used social media for professional purposes. However, this study also found that social media usage decreases with surgeon experience, particularly on Instagram and TikTok. 2 Despite this trend, many surgeons have used platforms like TikTok, which is a video-sharing platform known for its short and engaging clips, to engage with a larger audience. Its algorithm creates an ideal space for reaching large audiences quickly, making it a valuable tool for professionals looking to expand their social media presence.

To analyze how spine surgeons are using TikTok, we utilized Exolyt, a social media analytics tool that provides insights into account performance, such as engagement rates and most popular posts. This tool allowed us to identify the top influencers in the field of spine surgery and categorize their most popular content. In this article, we will explore how these surgeons engage with their audiences by categorizing their content into several key themes. These include Patient Education, Personal Life, Professional Insights, Trending Challenges and Social Engagement, and Social or Political Views. By examining their most popular posts, we can better understand how social media is redefining healthcare communication and setting new standards for medical engagement in the 21st century.

Patient Education

Patient education is at the cornerstone of effective healthcare delivery. Some spine surgeons are leveraging TikTok to explain complex medical concepts, surgical procedures,

Gregory Snigur, MS

John Sencaj, MD

Shriya Patel, BS

Sloane Ward, BS

Kern Singh, MD

common pathologies, and emerging technologies, enhancing public understanding and empowering patients to make informed decisions about their health. Among the analyzed TikTok influencers, patient education content was prominently featured. For example, 70%-80% of the 10 most popular posts from the TikTok accounts LadySpineDoc, Dr.Z_Neurosurgery, DonnallySpineConsult, and DrChollKim in the past year involved educational content. These four most popular influencer-spine surgeons have a combined 2.6 million followers and 155 million cumulative views.

DonnallySpineConsult and DrChollKim excel in breaking down complex surgical procedures into understandable 10- to 60-second videos. Some of their most popular educational videos, for instance, showcase step-by-step explanations of common surgical techniques using a combination of surgical footage and explanatory narration (example thumbnail shown in the Figure). Other posts feature animated videos of spinal fusion and lumbar discectomy surgery, illustrating the steps without graphic surgical images, making the content accessible to a broader audience. Similarly, Dr.Z_Neurosurgery frequently posts case studies of common spinal conditions, such as herniated discs and scoliosis, explaining symptoms, common etiology, physical examination signs, diagnostic tests, and treatment options. His content often includes patient imaging studies, like MRI and x-ray images, accompanied by thorough explanations. Other popular posts in this category include sharing practical

tips on preventive measures and exercises to maintain spinal health.

The hundreds of millions of views, likes, and shares on these educational posts suggest a substantial public appetite for accessible medical information. These videos demystify medical procedures, reduce patient anxiety, and promote health literacy, extending the educational impact beyond traditional clinical settings.

Personal Life

Sharing aspects of their personal lives on TikTok allows these surgeons to humanize themselves, making them more relatable to their audience. In 2020, a cohort review of 206 spine surgeons showed that publicly accessible social media accounts were associated with higher ratings on physician review websites. 3 By offering a glimpse into their lives outside the operating room and clinic, they build stronger connections with their followers and patients, fostering a sense of approachability.

LadySpineDoc and DrChollKim lead in this category, with both influencers incorporating elements of their personal lives into their TikTok content. LadySpineDoc commonly shares videos of her daily routines, family life, and hobbies, helping her 2.1 million followers see her as more than just a surgeon—a proud mom, wife, car enthusiast, boating fanatic, and more. These personal insights are crucial in breaking down the barriers between medical professionals and the public, making healthcare more approachable and less intimidating. They also provide a balance to the more tech -

nical and professional content, ensuring a well-rounded online presence. However, these types of posts can put surgeons at risk of blurring the line of professionalism.

Professional Insights

Professional insights provide followers with a deeper understanding of the medical field, offering behind-the-scenes looks at the life of a surgeon and the journey it takes to get there. This content can be particularly inspiring for premedical students, medical students, residents, and newly minted attendings.

LadySpineDoc and DonnallySpineConsult both excel in this category, with LadySpineDoc sharing several day-in-the-life videos that highlight her daily routines, challenges, and achievements as a spine surgeon. These posts not only showcase her expertise but also offer a realistic portrayal of the demands and rewards of a career in medicine.

DonnallySpineConsult, on the other hand, frequently shares personal stories about his training, including the hardships and triumphs he encountered on his journey to becoming a spine surgeon.

These professional insights are invaluable for followers interested in pursuing a career in medicine, as they provide a candid look at the realities of the profession. They also contribute to the surgeon’s authority and credibility, reinforcing their position as experts in their field.

Trending Challenges and Social Engagement

Participating in trending challenges and engaging with the broader TikTok community is

a strategy that helps these surgeons increase their visibility and relatability. By aligning themselves with popular trends, they can reach new audiences and stay relevant in the fast-paced world of social media.

Figure. Example TikTok post thumbnail from Dr.Z_Neurosurgery describing the process of deformity correction surgery

LadySpineDoc is particularly active in this category (nearly 20% of her most popular posts), frequently participating in TikTok trends that are popular across the platform. These posts often blend humor with educational content, allowing her to engage with trends while still providing value to her followers. She will commonly take the approach of “a spine surgeon’s thoughts on…” when responding to a trending topic. Engaging with trends allows these influencers to stay visible and connected with the TikTok community, ensuring that their educational and professional content reaches a broader audience. However, as with posting about their social lives, these posts may create murky waters.

Social or Political Views

Addressing social or political issues allows these surgeons to engage with broader societal concerns, reflecting their commitment to not only healthcare but also to the communities they serve. While this content is less frequent, it plays a critical role in shaping public discourse around healthcare policies and ethical issues.

LadySpineDoc and Dr.Z_Neurosurgery have occasionally used their platforms to discuss social and political issues. LadySpineDoc has posted about the importance of healthcare access and equity, using her platform to advocate for systemic changes. Dr.Z_Neurosurgery has touched on the importance of mental health in the medical profession, highlighting the need for greater support and awareness. These posts demonstrate that these surgeons are not only

medical experts but also engaged citizens who use their platforms to influence public opinion and advocate for positive change.

Ethical Considerations

Despite the aforementioned positives, social media use by medical professionals, including spine surgeons, presents several potential ethical and legal pitfalls. One of the primary concerns is the potential breach of patient confidentiality, wherein the accidental sharing of identifiable patient information can lead to serious legal consequences in the United States. Additionally, the informal nature of social media can blur the lines between professional and personal conduct, potentially damaging a surgeon’s reputation and undermining public trust in the medical profession. This has already been identified in an analysis of 1,020 orthopedic surgeons that found unprofessional content in 3.5% of social media users.4 Breaches of professionalism are especially likely when engaging with general trends or challenges. Misinformation is another significant risk, as posts may oversimplify complex medical issues or inadvertently spread unverified health advice, which can mislead patients. As De Martino et al correctly identified in their narrative review, there is little to no regulation on the information that is presented in this sphere of social media. 5 Therefore, the content of posts is largely at the discretion of the individual, putting significant responsibility on those with millions of followers. Finally, there is the danger of conflicts of interest, where promotional content might not be clearly distinguished

from professional advice, leading to ethical concerns about the commercialization of medical expertise. These potential challenges highlight the need for surgeons to approach social media with a commitment to professionalism, information accuracy, and patient privacy.

Conclusion

The analysis of these TikTok surgeon-influencers reveals a multifaceted approach to content creation, where education, personal branding, humor, professional insights, and social engagement intersect to create a dynamic and impactful online presence. Each influencer has developed a unique strategy that reflects their personal strengths and audience preferences, contributing to a broader movement that is redefining healthcare communication in the digital age. By leveraging TikTok’s wide reach and engaging format, these surgeons have successfully expanded their influence beyond the confines of traditional medical practice. They are not just participants in a trend but leaders in a digital movement

that is setting new standards for medical engagement and public health education in the 21st century.

As social media continues to evolve, becoming faster, more consumable, and increasingly personal, the role of medical professionals on these platforms will grow in importance. For future surgeons looking to incorporate a digital presence into their practice, it is crucial to ensure their online presence upholds the highest ethical standards. In 2018, Fidai el al published a commentary, providing a helpful list of tips for orthopedic surgeons trying to navigate social media. 6 With the rapid rise of platforms like TikTok, which foster even quicker, more intimate forms of communication, there is an urgent need for updated recommendations and thoughtful consideration of best practices. As the landscape of social media continues to shift, it is essential that medical professionals have access to resources that help them navigate these platforms responsibly, ensuring that their contributions to public health communication are both effective and ethical. l

References

1. Samtani RG, Webb A, Burleson J, et al. Spine surgeons social dilemma: benefits and risks of social media for spine surgery practice in the 21st century. Global Spine J. 2023;13:1441–1449.

2. Khalifé M, Afifi M, Chatelain L, et al. Social media use among French spine surgeons: an underrated tool? Neurochirurgie . 2023;69(6):101499.

3. Donnally CJ 3rd, McCormick JR, Pastore MA, et al. Social media presence correlated with improved online review scores for spine surgeons. World Neurosurg. 2020;141:e18–e25.

4. Call T, Hillock, R. Professionalism, social media, and the orthopaedic surgeon: what do you have on the Internet? Technol Health Care. 2017;25:531–539.

5. De Martino I, D’Apolito R, McLawhorn AS, Fehring KA, Sculco PK, Gasparini G. Social media for patients: benefits and drawbacks. Curr Rev Musculoskelet Med. 2017;10:141–145.

6. Fidai MS, Tramer JS, Jildeh TR, Stine S, Meta F, Makhni EC. Social media use in the field of orthopedic surgery. In: Makhni EC, Makhni MC, Swart EF, Bush-Joseph C, eds. Orthopedic Practice Management: Strategies for Growth and Success. Springer International Publishing; 2019:61–70.

From the 1Hospital for Special Surgery and 2Weill Cornell Medical College, both in New York, New York.

Adin M. Ehrlich, BA1

Fusion Assessment Comparison in Cervical Fusion Surgery

Anterior cervical discectomy and fusion (ACDF) and posterior cervical fusion (PCF) are well-established surgical management options for degenerative cervical disc disease.1 Their basis as standard-of-care has relied heavily upon the description of clinical outcome measures. While patient satisfaction and neurological status are highly important, assessing the procedure’s mechanical success via radiographic evaluation is necessary to guide future management. However, despite the expansive literature available, assessing the success of cervical fusion has remained challenging. Although the studies analyzing the efficacy of ACDF and PCF provide radiographic analysis of fusion, they are handicapped by the lack of standardization resulting from variations in imaging techniques and definitions of successful arthrodesis. 2–4 These variations have resulted in inconsistency in reported outcomes of radiographic analysis, differences in patient management, and the inability to determine which assessment method is most accurate, possibly limiting the ability of patients to receive standardized care across providers.

In recent years, the expanding literature discussing various criteria, modalities, and recent advancements in artificial intelligence have only made the need for standardization even more necessary. In this review, we examine and compare the various leading methodologies and criteria for evaluating cervical fusion success through radiographic techniques and explore what the future may hold for developing a gold standard.

What are the current leading radiographic methods for assessing cervical fusion?

The most utilized radiographic methods for assessing cervical fusion are dynamic radiographs and computed tomography (CT). Static radiographs have been utilized as an initial approach to assess ACDF status, but they correlate only between 43% and 82% with pseudoarthrosis detected via operative exploration. 5 Dynamic radiographs, utilizing flexion and extension lateral x-ray imaging, have been shown to be more reliable given their ability to evaluate interspinous motion to assess stability of the fusion site. 5 The closest to a “gold standard” technique is advanced imaging, specifically CT, as magnetic resonance imaging (MRI) is limited due to magnetic susceptibility artifacts that can obscure the evaluation of bone integrity.4,6,7

Tomoyuki Asada, MD1

Sheeraz A. Qureshi, MD1,2

Many studies utilize CT as their gold standard when assessing the accuracy of dynamic radiographs.4,5 However, first-line use of CT is not recommended because of its higher radiation doses compared to conventional radiographs and potential for metal artifacts to obscure findings.4

Dynamic Radiography

Recent studies have focused on establishing criteria for the use of dynamic radiographs.4,5 Several systematic reviews, including one by Rhee et al, recommend dynamic flexion-extension radiographs as the first-line imaging for ACDF assessment. Regarding PCF, the same study offers data to suggest static radiographs can be beneficial for assessing fusion; however, there were insufficient data to suggest whether it was superior to dynamic radiographs.4 It has been shown that the reliability of dynamic radiographs may be compromised by several factors, including debate regarding the acceptable measurement parameters and thresholds for motion, variability in the subjective measurement and analysis of images, and variability in the position of the patient with the x-ray machine. 3,8,9

The parameters in dynamic radiographs are Cobb angle change (CAC) and interspinous process movement (ISM). 4,5,7 CAC is measured as the difference in the angle obtained from the segmental Cobb angle of the fused vertebrae. ISM is defined as the difference in distances between the tips of spinous processes on flexion-extension radiographs. Articles described CAC thresholds ranging from >1° to >4°, while studies involving ISM

recommended thresholds ranging from 0 mm to 2 mm of movement between flexion-extension radiographs. Cannada et al attempted to validate these parameters with surgical exploration and found that a CAC of 2° had a sensitivity of 82% and specificity of 39%, and Pearson correlation with pseudoarthrosis of 0.28.10 ISM with a threshold of >2 mm of motion had greater sensitivity (91%) and specificity (89%) than CAC and a Pearson correlation with pseudoarthrosis of 0.77.10 Similarly, Song et al validated the use of ISM <1 mm as most accurate when compared with intraoperative exploration (κ = 0.725).11

Interobserver error is a challenging part of dynamic x-ray assessment. Studies have shown that due to the variance in assessment methodology and reliance on subjective assessment, surgeons may interpret results differently based on their experience and biases. 4,8,9,11 For example, a study by Skolasky et al found confirmation bias with higher fusion rates reported by the operating surgeon compared to an independent panel when assessing single level ACDF.12 To address interobserver reliability, Song et al evaluated ISM measurement at 150%, 25%, and 100% magnification and found both increased inter- and intraobserver reliability with a correlation coefficient of 0.796 at 150% magnification.11 Recent meta-analyses and systematic reviews have supported the described results and concluded ISM is superior to Cobb angle change and recommend viewing images at 150% magnification with thresholds of <1 mm of ISM alongside >4 mm of superjacent interspinous motion as confirming fusion.4,5,9

Additionally, patient positioning can alter radiographic imaging results. Pinter et al found that small isolated and combined changes in patient position and angle with the x-ray generator can influence the parameters, including the interspinous process distance, producing variability in imaging results.8 The authors concluded that dynamic radiographs are unreliable for assessing arthrodesis and emphasized the need for additional standardization measures to eliminate or significantly reduce variability. While several researchers have questioned the reliability of dynamic radiographs,4,5,7 the integration of advanced imaging modalities with artificial intelligence and machine learning is expected to improve accuracy and interrater reliability.

CT Imaging

CT demonstrates improved accuracy at identifying pseudoarthrosis due to improved interobserver reliability over standard radiographic methods and its ability to detail bridging trabecular bone directly at the fusion site. Despite its superiority, its use is only recommended after ambiguous radiographic findings, which have been described as interobserver variability, hardware artifacts, presence of radiolucent lines, and measurements that are close to the threshold value. 5,8,13

There are several radiographic parameters for CT-based fusion diagnosis described in the recent literature ranging from vague descriptions of fusion status to more specific measurement-based values. Parameters in-

Figure. Coronal computed tomography images 1 year after anterior cervical discectomy and fusion. Fusion is assessed utilizing the extragraft bone bridging method and pertinent features are highlighted by the arrows to show (A) successful fusion and (B) pseudoarthrosis.

clude the presence of bone bridging and lack of bony lucency at the graft/vertebral body junction and can be measured differently depending on the study. For example, Kim et al defined bony fusion as “fused with remodeling and trabeculae present” or “graft intact, not fully remodeled and incorporated, but no lucency present,”14 while others utilized more specific values, and some even calculated via multiple parameters. 4,5,15,16

Current literature and most recent systematic reviews identify the extragraft bone bridging (ExGBB) method from Song et al as the most accurate at assessing pseudarthrosis, which is defined as any peripheral bone bridging with no lucent lines crossing the peripheral margins of the operated disc space outside the graft or cage (Figure).4,5,15,16 Detection of ExGBB was obtained via multiple observers and was validated through surgical exploration of cases. ExGBB was found to have a high sensitivity (98.7%), specificity (92.1%), positive predictive value (92.1%), negative predictive value (98.7%), and interobserver reliability.16 While CT is superior to standard radiography, it is still limited to images obtained in a single moment of time and is therefore unable to assess for changes in the spine during motion, limiting its ability to reliability in cases of nonunion or pseudoarthrosis only seen with movement. 5

What emerging techniques will increase the accuracy of assessing cervical fusion?

Over the past decade, artificial intelligence and machine learning have been applied to the assessment of radiographic parameters

CT demonstrates improved accuracy at identifying pseudoarthrosis...over standard radiographic methods.... Despite its superiority, its use is only recommended after ambiguous radiographic findings

and images throughout the medical field. More recently, they have been applied to improve the accuracy of cervical fusion assessments.13 Two recent studies discuss the use of a convolutional neural network model to assess cervical fusion parameters following ACDF using dynamic imaging. Park et al created a model that utilized extracted radiographs in 3 positions (flexion, extension, and neutral) of only the fusion segment and close periphery to output a final decision of fusion or nonunion. The model had an accuracy of 89.5% when compared to observations utilizing both dynamic radiographs and CT images by orthopedic surgeons.13

More recently, a model described by Ham et al was able to detect spinous processes in radiographs with 99.2% accuracy (sensitivity 97.0%, precision 97.4%) and then measure the interspinous distance within flexion-extension paired radiographs to calculate ISM.17 Compared to human observers, the model obtained a Cohen’s kappa of 0.82 when detecting the presence of segmental motion, indicating a strong level of agreement.17

Radioisometric analysis (RSA) is another method of assessing cervical fusion but has remained mostly experimental thus far.7 A

CERVICAL SPINE

study by Parashin et al attempted to assess the accuracy, precision, and feasibility of RSA in PCF and posterior lumbar fusion procedures using artificial and cadaveric spine models with implanted beads.18 They found high accuracy and detectability of the beads in cervical and lumbar segments with lower precision in the cervical compared to lumbar region. This study suggests RSA is feasible in the application of cervical spinal fusion and recommends continued investigation into the use of RSA for spinal fusion assessment.18

References

1. Buttermann GR. Anterior cervical discectomy and fusion outcomes over 10 years: a prospective study. Spine . 2018;43(3):207-214.

2. Balouch E, Burapachaisri A, Woo D, et al. Assessing postoperative pseudarthrosis in anterior cervical discectomy and fusion (ACDF) on dynamic radiographs using novel angular measurements. Spine . 2022;47(16):1151-1156.

3. Noordhoek I, Koning MT, Vleggeert-Lankamp CLA. Evaluation of bony fusion after anterior cervical discectomy: a systematic literature review. Eur Spine J. 2019;28(2):386-399.

4. Rhee JM, Chapman JR, Norvell DC, Smith J, Sherry NA, Riew KD. Radiological determination of postoperative cervical fusion: a systematic review. Spine . 2015;40(13):974-991.

5. Lin W, Ha A, Boddapati V, Yuan W, Riew KD. Diagnosing pseudoarthrosis after anterior cervical discectomy and fusion. Neurospine . 2018;15(3):194-205.

6. Godlewski B, Bebenek A, Dominiak M, Bochniak M, Cieslik P, Pawelczyk T. Reliability and utility of various methods for evaluation of bone union after anterior cervical discectomy and fusion. J Clin Med. 2022;11(20):6066.

Conclusion

The definition and description of a gold standard in cervical spinal fusion through radiographic analysis is still an ongoing debate. The information in the present article is intended to present an overview of techniques so that readers may better understand what the current literature suggests is most valid. While there is still no standardized method of assessing cervical fusion, future studies will only help further define a gold standard. l

7. Selby MD, Clark SR, Hall DJ, Freeman BJC. Radiologic assessment of spinal fusion. J Am Acad Orthop Surg. 2012;20(11):694-703.

8. Pinter ZW, Skjaerlund J, Michalopoulos GD, et al. Dynamic radiographs are unreliable to assess arthrodesis following cervical fusion: a modeled radiostereometric analysis of cervical motion. Spine (Phila Pa 1976). 2023;48(2):127-136.

9. Oshina M, Oshima Y, Tanaka S, Riew KD. Radiological fusion criteria of postoperative anterior cervical discectomy and fusion: a systematic review. Glob Spine J. 2018;8(7):739-750.

10. Cannada LK, Scherping SC, Yoo JU, Jones PK, Emery SE. Pseudoarthrosis of the cervical spine: a comparison of radiographic diagnostic measures. Spine (Phila Pa 1976). 2003;28(1):46-51.

11. Song KS, Piyaskulkaew C, Chuntarapas T, et al. Dynamic radiographic criteria for detecting pseudarthrosis following anterior cervical arthrodesis. J Bone Joint Surg Am. 2014;96(7):557-563.

12. Skolasky RL, Maggard AM, Hilibrand AS, et al. Agreement between surgeons and an independent panel with respect to surgical site fusion after single-level anterior cervical spine surgery: a prospective, multicenter study. Spine . 2006;31(15):E503-E506.

13. Park S, Kim JK, Chang MC, Park JJ, Yang JJ, Lee GW. Assessment of fusion after anterior cervical discectomy and fusion using convolutional neural network algorithm. Spine . 2022;47(23):1645-1650.

14. Kim CH, Chung CK, Hahn S. Autologous iliac bone graft with anterior plating is advantageous over the stand-alone cage for segmental lordosis in single-level cervical disc disease. Neurosurgery 2013;72(2):257-265; discussion 266.

15. Riew KD, Yang JJ, Chang DG, et al. What is the most accurate radiographic criterion to determine anterior cervical fusion? Spine J. 2019;19(3):469-475.

16. Song KS, Chaiwat P, Kim HJ, Mesfin A, Park SM, Riew KD. Anterior cervical fusion assessment using reconstructed computed tomographic scans: surgical confirmation of 254 segments. Spine (Phila Pa 1976). 2013;38(25):2171-2177.

17. Ham DW, Choi YS, Yoo Y, Park SM, Song KS. Measurement of interspinous motion in dynamic cervical radiographs using a deep learning-based segmentation model. J Neurosurg Spine . 2023;39(3):329-334.

18. Parashin S, Gascoyne T, Zarrabian M. A phantom and cadaveric study of radiostereometric analysis in posterior cervical and lumbar spinal fusion. Spine J. 2020;20(8):1333-1343.

From the Department of Orthopaedic Surgery at Rush University Medical Center in Chicago, Illinois.

Biologics in TLIF—A Focus on Cost and Efficacy

Minimally invasive surgical (MIS) techniques in spine surgery are increasingly being utilized to treat a wide range of spine pathologies. With more than 400,000 spine fusion procedures performed annually in the United States, it has become one of the most common and well-established treatments for degenerative disorders, spine trauma, tumors, and structural deformities.1 Bone graft substitutes are commonly used during spinal arthrodesis surgery, and while numerous factors influence the success of spinal arthrodesis, choosing the most appropriate biologic is essential to optimize both efficacy and safety. The current variability in the use of bone grafts and substitutes reflects uncertainty about their effectiveness, outcomes, and associated costs. An evidence-based approach to cost-effective decision-making should aim to maximize patient-centered benefits or outcomes while minimizing costs and risks. The present brief review will focus on the cost and efficacy of bone morphogenetic protein (BMP) in MIS transforaminal lumbar interbody fusion (TLIF) surgery.

BMP Utilization and Efficacy

Using the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project, Singh et al analyzed national epidemiologic trends in BMP use for spinal arthrodesis from 2002 to 2011, with a focus on the impact of the

2008 Food and Drug Administration warning. Consistent with earlier studies, they observed a steady annual increase in BMP utilization, increasing from 0.6% BMP use in 2002 to 26.9% in 2011 across various types of spinal fusions. 2 The posterior lumbar fusion cohort accounted for the majority of spinal fusions that used BMP, representing 76.8% of all spinal fusions between 2002 and 2011. 2 However, in a more recent review, Wadhwa et al retrospectively reviewed a total of 316,070 patients who underwent spinal fusion from 2006 to 2015 where BMP was used in 60,249 cases (19.1%) and found that BMP utilization rates decreased from 23.1% in 2006 to 12.0% in 2015. This was not stratified to delineate the rates for MIS TLIF, but BMP use in posterior lumbar fusions decreased from 31.5% in 2006 to 15.8% in 2015. 3

Nevertheless, BMP is still widely used and its cost effectiveness remains in question. In a single institution retrospective cohort study of 187 patients with 2-year follow-up, Khan et al found that BMP in TLIF procedures was relatively effective for achieving bone fusion at rates similar to autograft. The fusion rate for the BMP and non-BMP groups

Daniel Shinn, MD

Vincent P. Federico, MD

Arash Sayari, MD

BIOLOGICS

was 92.7% and 92.3%, respectively, and the overall pseudoarthrosis rate was 7.5% (14 of 187 patients).4 In a systematic review of clinical studies published between 2000 and 2012 comparing fusion rates after posterior lumbar interbody fusion (PLIF)/TLIF (not limited to MIS) surgery with versus without BMP, Galimberti et al found that the average fusion rate 24 months after surgery was 95.7% for PLIF/TLIF (n = 141) with BMP and 89.5% (n = 86) without BMP. This difference was not statistically significant, but the lack of

significance can be explained by variability in BMP dosing, surgical methods, and the quality of the studies. 5 Although MIS TLIF was not differentiated from open TLIF, there is literature to support comparable fusion rates. In an open vs MIS TLIF retrospective cohort study with 148 MIS patients, Price et al demonstrated the fusion rate was similar for both open and MIS TLIF (91% overall). More importantly though, they found BMP use was associated with higher fusion rate (93% vs 83%) at 1-year, regardless of approach.6

aThere are no significant differences in fusion rates among these groups; however, they do demonstrate significantly higher fusion rates when compared to the rest ( p < 0.05).

Abbreviations: BMA, bone marrow asparate; DBM, demineralized bone matrix; rhBMP-2, recombinant human bone morphogenetic protein-2.

Source: Figure adapted from Chang KY, Hsu WK. Spinal biologics in minimally invasive lumbar surgery.  Minimally Invasive Surgery. 2018;2018:5230350. https://doi.org/10.1155/2018/5230350

Table. Fusion Rates for Various Bone Grafts in Posterior Approaches to Minimally Invasive Interbody Fusions

Furthermore, there has been a dose-dependent relationship demonstrated for BMP in MIS TLIF. Lytle et al retrospectively reviewed 690 patients who underwent MIS TLIF from 2009 to 2014 and found that odds of fusion increased by 2.02 when BMP dose range was increased from 0.16–1 mg/level to 1.0–2 mg/ level, but fusion odds did not increase when BMP dose increased to more than 2 mg/ level. Overall fusion was 95.2% with a mean follow-up of 19 months.7 BMP also performs well in combination with autograft. In a meta-analysis that compared fusion rates of different graft materials used in MIS-TLIF, Parajón et al reported a 95.3% fusion rate after local autograft + BMP compared to 91.8% with local autograft alone (no statistics reported). The highest fusion rate was observed with a combination of local autograft with bone extender and BMP (99.1%). 8

BMP Complications and Costs

The primary limitations of the frequency of BMP use have been related to reported complications and questionable cost effectiveness. Some complications associated with BMP include osteolysis, graft subsidence, retrograde ejaculation, and urological issues. 9-13 In the previously mentioned retrospective cohort study, Khan et al also found similar complication rates, with the BMP group exhibiting slightly higher rates of radiculitis and seroma (OR = 4.53, 95% CI, 1.42–14.5).4 However, these complications are rare. Crandall et al reviewed 509 patients undergoing open TLIFs and discovered similar complications at an average 5-year follow-up, with pseudoarthrosis in 0.92%,

Despite reductions in usage, BMP remains commonly used, showing fusion rates comparable to autografts but raising concerns about costeffectiveness and complication risks.

seroma in 0.4%, and ectopic bone growth in 0.6%.14

More specifically in MIS TLIFs, in a large case series of 573 patients, Singh et al reported that 10 patients (1.7%) required additional procedures due to persistent radiculopathy, neuroforaminal bone growth, vertebral body osteolysis, or cage migration. Thirty-nine patients (6.8%) underwent reoperations for symptomatic pseudarthrosis. In their cost analysis for this single-surgeon, single-institution study, the average cost per procedure was $19,224, while the costs for reoperation were $14,785 per case for neuroforaminal bone growth and $20,267 for pseudarthrosis.15 These are some of the potential costs that should be considered when weighing the risks and benefits of BMP use. The Medicare database study by Wadhwa et al also reported that BMP reimbursement does not increase proportionally with BMP cost: BMP use was associated with a total cost increase of about $4,597 in posterior lumbar fusions but a reimbursement increase of $964. 3

Alternative Biologics

Traditionally, autologous bone grafting, particularly iliac crest bone graft (ICBG), was regarded as the gold standard for spi-

nal arthrodesis. However, due to concerns about complications at the harvest site, limited availability, and associated morbidity, surgeons have increasingly turned to alternative bone graft options that offer osteogenic, osteoinductive, and/or osteoconductive properties. These alternatives include allografts, demineralized bone matrix, ceramics, mesenchymal stem cells, and recombinant human bone morphogenetic proteins.16 ICBG provides both cortical and cancellous grafts without the added cost of commercial alternatives. It offers a substantial amount of bone and eliminates the risk of disease transmission or histoincompatibility. However, ICBG harvesting can lead to complications, including infection, pain, scarring, and graft site fractures.17,18

Modern surgical techniques have reduced these risks by preserving the inner cortex and carefully closing wounds, helping to maintain the iliac crest’s shape and reduce chronic pain. Despite the potential complications, ICBG remains an effective bone graft option, supported by high fusion rates of up to 93% in MIS TLIF. 8 Haws et al reviewed 149 patients who underwent MIS TLIF with ICBG or BMP, and the authors found the ICBG cohort demonstrated increases in intraoperative blood loss and longer operative times but no significant differences in complication or reoperation rates.19 In a prospective series of patients undergoing primary, single-level MIS TLIF with ICBG was compared to a historical cohort of patients that received BMP-2. The authors found that ICBG was associated with decreased total direct costs ($19,315 vs $21,645, P < 0.001) as compared to BMP-2. 20

Among the allograft options, i-Factor, also known as anorganic bone matrix combined with Peptide 15 (P-15), has been utilized to augment lumbar spine fusion. 21 In a 2-year prospective clinical trial, Lauweryns et al reported the efficacy of i-Factor in PLIF surgeries. By 24 months, i-Factor had a fusion rate of 95.56% and autograft had a rate of 93.33%. In this study, i-Factor not only promoted fusion but also achieved it more rapidly than traditional autografts in PLIF procedures. 21 The unit cost of i-Factor can range from $757 to $2090, depending the size. 22 In anterior cervical discectomy and fusion, Thaci et al found the incremental cost-effectiveness ratio of i-Factor use was $13,333 per quality-adjusted life year at 90 days and demonstrated a greater benefit and a lower cost at 1 year when compared to the autograft cohort. 23 However, further studies are needed to assess the cost utility of i-Factor in MIS TLIFs.

Conclusion

The present review briefly explores the usage, efficacy, and complications associated with BMP in MIS TLIF surgeries alongside a couple of alternative biologics. Over the years, the use of BMP in spinal arthrodesis has fluctuated due to Food and Drug Administration warnings and changing trends, as analyzed by Singh et al and Wadhwa et al. Despite reductions in usage, BMP remains commonly used, showing fusion rates comparable to autografts but raising concerns about cost-effectiveness and complication risks. The discussion extends to alternative graft

materials like autografts, allografts, and innovative products like i-Factor, which have their benefits and limitations. Cost considerations remain critical, and randomized controlled trials are warranted to directly compare the efficacy and costs in

References

1. Rajaee SS, Bae HW, Kanim LE, Delamarter RB. (2012). Spinal fusion in the United States: analysis of trends from 1998 to 2008. Spine . 2012;37(1):67-76.

2. Singh K, Nandyala SV, Marquez-Lara A, Fineberg SJ. Epidemiological trends in the utilization of bone morphogenetic protein in spinal fusions from 2002 to 2011. Spine . 2014;39(6):491-496.

3. Wadhwa H, Wu JY, Malacon K, Ames CP, Ratliff JK, Zygourakis CC. Trends, payments, and costs associated with BMP use in Medicare beneficiaries undergoing spinal fusion. Spine J. 2023;23(6):816-823.

4. Khan TR, Pearce KR, McAnany SJ, Peters CM, Gupta MC, Zebala LP. Comparison of transforaminal lumbar interbody fusion outcomes in patients receiving rhBMP-2 versus autograft. Spine J. 2018;18(3):439-446.

5. Galimberti F, Lubelski D, Healy AT, et al. A systematic review of lumbar fusion rates with and without the use of rhBMP-2. Spine . 2015;40(14):1132-1139.

6. Price JP, Dawson JM, Schwender JD, Schellhas KP. Clinical and radiologic comparison of minimally invasive surgery with traditional open transforaminal lumbar interbody fusion: a review of 452 patients from a single center. Clin Spine Surg. 2018;31(2):E121-E126.

7. Lytle EJ, Slavnic D, Tong D, et al. Minimally effective dose of bone morphogenetic protein in minimally invasive lumbar interbody fusions: six hundred ninety patients in a dose-finding longitudinal cohort study. Spine . 2019;44(14):989-995.

8. Parajón A, Alimi M, Navarro-Ramirez R, et al. Minimally invasive transforaminal lumbar interbody fusion: meta-analysis of the fusion rates. What is the optimal graft material? Neurosurgery. 2017;81(6):958-971.

MIS TLIF. The narrative underscores the need for balancing efficacy, safety, and costs in choosing the appropriate graft material for MIS TLIF procedures, advocating for an evidence-based approach in clinical decision-making. l

9. Vaidya R, Weir R, Sethi A, Meisterling S, Hakeos W, Wybo CD. Interbody fusion with allograft and rhBMP-2 leads to consistent fusion but early subsidence. J Bone Joint Surg Br. 2007;89(3):342-345.

10. Smoljanovic T, Siric F, Bojanic I. Six-year outcomes of anterior lumbar interbody arthrodesis with use of interbody fusion cages and recombinant human bone morphogenetic protein-2. J Bone Joint Surg Am. 2010;92(15):2614-2615.

11. Jarrett CD, Heller JG, Tsai L. Anterior exposure of the lumbar spine with and without an “access surgeon”: morbidity analysis of 265 consecutive cases. Clin Spine Surg. 2009;22(8):559-564.

12. Carragee EJ, Hurwitz EL, Weiner BK. A critical review of recombinant human bone morphogenetic protein-2 trials in spinal surgery: emerging safety concerns and lessons learned. Spine J. 2011;11(6):471-491.

13. Carragee EJ, Mitsunaga KA, Hurwitz EL, Scuderi GJ. Retrograde ejaculation after anterior lumbar interbody fusion using rhBMP-2: a cohort controlled study. Spine J. 2011;11(6):511-516.

14. Crandall DG, Revella J, Patterson J, Huish E, Chang M, McLemore R. Transforaminal lumbar interbody fusion with rhBMP-2 in spinal deformity, spondylolisthesis, and degenerative disease–part 1: large series diagnosis related outcomes and complications with 2-to 9-year follow-up. Spine . 2013;38(13):1128-1136.

15. Singh K, Nandyala SV, Marquez-Lara A, et al. Clinical sequelae after rhBMP-2 use in a minimally invasive transforaminal lumbar interbody fusion. Spine J. 2013;13(9):1118-1125.

16. Kannan A, Dodwad SNM, Hsu WK. Biologics in spine arthrodesis. Clin Spine Surg. 2015;28(5):163-170.

17. Robertson PA, Wray AC. Natural history of posterior iliac crest bone graft donation for spinal surgery: a prospective analysis of morbidity. Spine . 2001;26(13):1473-1476.

18. Sengupta DK, Truumees E, Patel CK, et al. Outcome of local bone versus autogenous iliac crest bone graft in the instrumented posterolateral fusion of the lumbar spine. Spine. 2006;31(9):985-991.

19. Haws BE, Khechen B, Yoo JS, et al. Impact of iliac crest bone grafting on postoperative outcomes and complication rates following minimally invasive transforaminal lumbar interbody fusion. Neurospine . 2019;16(4):772-779.

20. Haws BE, Khechen B, Narain AS, et al. Iliac crest bone graft for minimally invasive transforaminal lumbar interbody fusion: a prospective analysis of inpatient pain, narcotics consumption, and costs. Spine . 2018;43(18):1307-1312.

21. Lauweryns P, Raskin Y. Prospective analysis of a new bone graft in lumbar interbody fusion: results of a 2-year prospective clinical and radiological study. Int J Spine Surg. 2015;9:2.

22. Bernatz JT, Fisher MW, Pinter ZW, Sebastian AS. Controversies in spine surgery: is i-Factor superior to bone morphogenic protein for achieving spine fusion? Clin Spine Surg. 2023;36(6):224-226.

23. Thaci B, Yee R, Kim K, Vokshoor A, Johnson JP, Ament J. Cost-effectiveness of peptide enhanced bone graft i-Factor versus use of local autologous bone in anterior cervical discectomy and fusion surgery. Clinicoecon Outcomes Res. 2021;13:681-691.

From the 1Hospital for Special Surgery and 2Weill Cornell Medical College, both in New York, New York.

Bone Quality Assessment in Spine Surgery

The prevalence of osteopenia and osteoporosis among spine surgery patients older than 50 years has been estimated to be as high as 46% and 31%, respectively.1 Identifying osteoporosis prior to spine reconstruction surgery is critical, particularly given the aging US population and the increasing rates of spinal fusion procedures. 2,3 Osteoporosis is associated with worse outcomes and higher rates of complications in spine surgery, including pedicle screw loosening, instrumentation failure, pseudarthrosis, vertebral compression fractures, proximal junctional failure (PJF), and revision surgery.4,5 Optimizing bone quality can positively affect the clinical outcomes.6 Therefore, assessing bone quality in spine surgery patients is a crucial step for guiding clinical decision-making and improving postoperative outcomes.2,3 Enhanced knowledge of differing methods to assess bone quality would be beneficial in the preoperative assessment of potential spinal fusion patients.

Overview of Bone Quality Assessment Methods

Several imaging modalities are available for a noninvasive evaluation of bone quality in

the spine. Currently, dual-energy x-ray absorptiometry (DEXA) scans are considered the gold standard for bone mineral density (BMD) assessment, which is a critical component of overall bone quality assessment.4 DEXA with trabecular bone score can assess bone quality besides BMD. Computed tomography (CT) and magnetic resonance imaging (MRI) are frequently used in the preoperative assessment of spine surgery patients. Recently, quantitative computed tomography (QCT)-Hounsfield units (HUs) and MRI-based vertebral bone quality (VBQ) have gained increasing attention as alternative methods for estimating bone quality.7 These imaging techniques are valuable for identifying candidates for preoperative intervention for osteopenia/osteoporosis, selecting appropriate surgical techniques such as interbody fusion, and determining the need for augments such as cement augmentation or tethering. 8

DEXA is a widely used method for preoperative planning due to its strong evidence base. 4 It provides a planar image that can assess BMD. However, DEXA has limitations, such as being influenced by factors like bone size, calcified tissues, and degenerative changes, which can lead to falsely elevated T-scores. 4,9,10 While DEXA-based trabecular bone score offers some additional insights into bone microstructure, it still has

Sereen Halayqeh, MD1

Tomoyuki Asada, MD1

Sravisht Iyer, MD1,2

the inherent limitations of 2-dimensional imaging.11

For this reason, CT, specifically HU value and QCT, are increasingly used for evaluating BMD in spine surgery planning.12 QCT provides true volumetric BMD measurements and offers a 3-dimensional view, making it less susceptible to the degenerative changes that can affect DEXA results.4,7 It measures BMD in mg/cm³ and is not influenced by bone size or aortic calcifications. 9 However, like DEXA, CT involves exposure to ionizing radiation, which requires consideration when ordering these tests. 3

MRI-based bone quality assessment, such as VBQ, is a newer technique that uses T1-weighted MRI to identify osteopenia and osteoporosis with high accuracy (Figure).13 It is not affected by degenerative cortical changes, it is noninvasive, and it avoids the use of ionizing radiation, making it a safer option for patients. 3,11 However, this method can be limited by the potential for claustrophobia in patients, longer tests times, higher costs, and artifacts from metallic implants.7

Predicting Postoperative Spinal Complications

Prediction Ability of DEXA

Published literature indicates that low BMD can negatively impact fusion constructs. In a study that compared T-scores of patients with subsidence to those without subsidence who underwent lumbar fusion, researchers found that the mean T-score in patients with subsidence was -1.65 compared to -0.45 in patients without subsidence, and they con-

cluded that patients with DEXA T-scores < -1.0 undergoing lumbar fusion are at a much higher risk of developing cage subsidence.14 In a propensity-matched comparison study of adult spinal deformity patients to elucidate whether low BMD is a true risk factor for PJF, patients were grouped as having mildly low to normal BMD (T-score ≥ -1.5) or significantly low BMD (T-score <-1.5). They found that the incidence of PJF was significantly higher in the low BMD group.15 Similar findings were confirmed by another study that found patients with PJF have significantly

Figure. Measurement methods for vertebral bone quality (VBQ) score. Noncontrast T1-weighted magnetic resonance images of the lumbar spine were utilized to assess bone quality (VBQ) score. This score was calculated by placing regions of interest in the medullary areas of the L1-L4 vertebral bodies and within the cerebrospinal fluid space at the L3 level.

lower BMD than non-PJF patients (T-scores of -1.4 vs. -0.7, respectively).16 In light of these findings, it seems reasonable to suggest that a T-score below -1.0 may generally indicate a potential need for preoperative interventions to address concerns about bone quality.

Prediction Ability of HU Value

CT is not a replacement for DEXA, but if available, HU values can help in predicting surgical spinal complications. For instance, CT scans are used to screen osteoporosis before spinal fusion to help in planning for the surgical treatment.4 A recent review of 42 studies that including a measure of spinal BMD showed that patients with HU values >160 demonstrated significant low risk of osteoporosis, whereas HU values <110 were significantly correlated with osteoporosis.4 HU values were also used to evaluate BMD to lower risks of interbody cage subsidence. Several studies showed that low HU values preoperatively are significantly associated with cage subsidence after fusion.17-19 One of these studies was a review of current literature in which they created a cut-off for HU values to predict postoperative complications.18 They found that patients with HU values under 120 are at risk for subsidence, screw loosening, and pseudarthrosis of interbody fusion, while those with HU values under 150 are at risk for posterolateral fusion pseudarthrosis and adjacent segment fractures.18

Prediction Ability of VBQ Score

While evidence for using VBQ in predicting construct failure is limited, available studies have suggested usefulness of VBQ values in

spinal instrumentation. These studies indicated that VBQ is useful in predicting subsidence of fusion cages, vertebral fractures, PJF, and reoperation after lumbar fusion. 20-24 Higher VBQ values have been correlated with implant subsidence, reoperation rates, and vertebral compression fractures. A study investigating the association between VBQ scores and reoperation after lumbar fusion found that the average VBQ score for patients requiring reoperation was 2.92, compared to 3.29 for those who did not. 23 Among those needing reoperation, 70% had a VBQ greater than 3, while only 38.3% of those not requiring reoperation had a VBQ greater than 3. Preoperative VBQ scores were also significant predictors of PJF in patients undergoing corrective surgery for adult spinal deformity, as a recent study showed that the mean VBQ scores were 3.13 for patients with PJF and 2.46 for patients without, with a predictive accuracy of 94.3%. 24

Comparison of the 3 Methods

MRI and CT-based assessment are emerging techniques for evaluating BMD, particularly in predicting complications and construct failure following fusion surgery. Although these newer methods show promise, their correlations with traditional DEXA are not well established. Previous studies indicate that while HU and VBQ measurements are useful for BMD assessment, they only moderately correlate with traditional DEXA scores.7,20,25,26 When comparing these methods for predicting osteoporosis before spinal surgery, VBQ and HU values were more associated with identifying patients with

osteoporosis and corresponding fractures than the T score. 25,27 One study suggested that HU scores outperform VBQ scores in screening for osteoporosis. 28

In terms of prediction of spinal construct complications, HU value and VBQ score have been reported to be superior to DEXA in predicting complications. 25,29 For predicting cage subsidence, both HU and VBQ scores demonstrated superior predictive ability for the amount of cage subsidence than DEXA. 21,25 In patients with lumbar pedicle screw fixation, VBQ was a better predictor of pedicle screw loosening than HU, with a VBQ threshold of 3.05 optimizing sensitivity and specificity for predicting this outcome. 30

Emerging Technologies and Future Directions

Bone quality assessment using DEXA, CT Hounsfield units, and MRI-based vertebral bone quality (VBQ) is crucial in spine surgery, particularly for patients with osteopenia or osteoporosis, to minimize complications such as screw loosening and cage subsidence

Conclusion

Preoperative radiographic evaluation of bone quality may include DEXA, CT, and MRI. The identification and assessment of poor bone health preoperatively can impact postoperative outcomes with the potential to reduce osteoporosis-related complications. In recent years, new tools and diagnostic techniques have been developed to refine bone quality and overcome the drawbacks of conventional techniques. While DEXA can still represent the reference standard for assessing osteoporosis, advancements in alternative imaging modalities show promise. Moving forward, developing a comprehensive, national-level protocol for preoperative bone quality evaluation and preoperative intervention will be essential to optimize surgical outcomes and patient care. l

The ability to accurately determine spinal bone quality using alternative imaging modalities instead of DEXA is now a key area of emerging interest to spine surgeons. Dual-energy CT and spectral-detector CT are new methods being evaluated for BMD assessment of lumbar bone. They showed strong correlation with bone strength in human cadaver vertebrae specimens and superior predictive ability for the 2-year risk to sustain an osteoporosis-associated fracture without requiring reference compared to DEXA and HU measurements. 31,32 Given that preoperative CT is routinely performed before spinal fusion, utilization of these novel techniques may be able to improve the screening and preoperative optimization protocols. Another growing interest is quantitative ultrasound (QUS) measurements for detecting and managing osteoporosis. QUS methods have several potential advantages over the conventional measures (absence of ionizing radiation, portable machines, lower cost), but such methods await broader validation regarding their accuracy in identifying osteoporotic patients in spine surgery. 33,34

BONE HEALTH

References

1. Chin DK, Park JY, Yoon YS, et al. Prevalence of osteoporosis in patients requiring spine surgery: incidence and significance of osteoporosis in spine disease. Osteoporos Int. 2007;18(9):1219–1224.

2. Witham TF, Cottrill E, Pennington Z. Is preoperative bone health assessment and optimization in spine surgery a good idea [editorial]? Neurosurg Focus. 2020;49(2):E3.

3. Lin W, He C, Xie F, et al. Assessment of bone density using the 1.5 T or 3.0 T MRI-based vertebral bone quality score in older patients undergoing spine surgery: does field strength matter? Spine J. 2023;23(8):1172–1181.

4. Deshpande N, Hadi MS, Lillard JC, et al. Alternatives to DEXA for the assessment of bone density: a systematic review of the literature and future recommendations. J Neurosurg. 2023;38(4):436–445.

5. Sardar ZM, Coury JR, Cerpa M, et al. Best practice guidelines for assessment and management of osteoporosis in adult patients undergoing elective spinal reconstruction. Spine. 2022;47(2):128–135.

6. Pasqualini I, Huffman N, Keller SF, et al. Team approach: bone health optimization in orthopaedic surgery. JBJS Rev. 2023;11(12):e23.00178.

7. Ahmad A, Crawford CH III, Glassman SD, Dimar JR II, Gum JL, Carreon LY. Correlation between bone density measurements on CT or MRI versus DEXA scan: a systematic review. N Am Spine Soc J. 2023;14:100204.

8. Lehman RA Jr, Kang DG, Wagner SC. Management of osteoporosis in spine surgery. J AAOS. 2015;23(4):253–263. https://doi.org/10.5435/JAAOS-D-14-00042

9. Salzmann SN, Okano I, Jones C, et al. Preoperative MRI-based vertebral bone quality (VBQ) score assessment in patients undergoing lumbar spinal fusion. Spine J. 2022;22(8):1301–1308.

10. Choi MK, Kim SM, Lim JK. Diagnostic efficacy of Hounsfield units in spine CT for the assessment of real bone mineral density of degenerative spine: correlation study between T-scores determined by DEXA scan and Hounsfield units from CT. Acta Neurochirurgica. 2016;158(7):1421–1427.

11. Pu M, Zhong W, Heng H, et al. Vertebral bone quality score provides preoperative bone density assessment for patients undergoing lumbar spine surgery: a retrospective study. J Neurosurg. 2023;38(6):705–714.

12. Nagata K, Glassman SD, Dimar JR II, et al. Comparison of bone mineral density

in children and adolescents on CT versus DEXA scan. Spine. 2024;49(19):E322–E326.

13. Ehresman J, Pennington Z, Schilling A, et al. Novel MRI-based score for assessment of bone density in operative spine patients. Spine J. 2020;20(4):556–562.

14. Tempel ZJ, Gandhoke GS, Okonkwo DO, Kanter AS. Impaired bone mineral density as a predictor of graft subsidence following minimally invasive transpsoas lateral lumbar interbody fusion. Eur Spine J. 2015;24(suppl 3):414–419.

15. Yagi M, Fujita N, Tsuji O, et al. Low bone-mineral density is a significant risk for proximal junctional failure after surgical correction of adult spinal deformity: a propensity score-matched analysis. Spine. 2018;43(7):485–491.

16. Wang H, Ma L, Yang D, et al. Incidence and risk factors for the progression of proximal junctional kyphosis in degenerative lumbar scoliosis following long instrumented posterior spinal fusion. Medicine. 2016;95(32):e4443.

17. Xi Z, Mummaneni PV, Wang M, et al. The association between lower Hounsfield units on computed tomography and cage subsidence after lateral lumbar interbody fusion. Neurosurg Focus. 2020;49(2):E8.

18. Zaidi Q, Danisa OA, Cheng W. Measurement techniques and utility of Hounsfield unit values for assessment of bone quality prior to spinal instrumentation: a review of current literature. Spine. 2019;44(4):E239–E244.

19. Mi J, Li K, Zhao X, Zhao CQ, Li H, Zhao J. Vertebral body Hounsfield units are associated with cage subsidence after transforaminal lumbar interbody fusion with unilateral pedicle screw fixation. Clin Spine Surg. 2017;30(8):E1130–E1136.

20. Courtois EC, Davidson IU, Ohnmeiss DD, Guyer RD. Evaluating alternatives to dual-energy x-ray absorptiometry for assessing bone quality in patients undergoing spine surgery. J Neurosurg. 2023;40(1):84–91.

21. Hu YH, Yeh YC, Niu CC, et al. Novel MRIbased vertebral bone quality score as a predictor of cage subsidence following transforaminal lumbar interbody fusion. J Neurosurg. 2022;37(5):654–662.

22. Li R, Yin Y, Ji W, et al. MRI-based vertebral bone quality score effectively reflects bone quality in patients with osteoporotic vertebral compressive fractures. Eur Spine J. 2022;31(5):1131–1137.

23. Ehresman J, Ahmed AK, Lubelski D, et al. Vertebral bone quality score and postop -

erative lumbar lordosis associated with need for reoperation after lumbar fusion. World Neurosurg. 2020:140;e247–e252.

24. Kuo CC, Soliman MAR, Aguirre AO, et al. Vertebral bone quality score independently predicts proximal junctional kyphosis and/or failure after adult spinal deformity surgery. Neurosurg. 2023;92(5):945–954.

25. Agaronnik ND, Giberson-Chen C, Bono CM. Using advanced imaging to measure bone density, compression fracture risk, and risk for construct failure after spine surgery. Spine J. 2024;24(7):1135–1152.

26. Razzouk J, Bouterse A, Shin D, et al. Correlations among MRI-based cervical and thoracic vertebral bone quality score, CT-based Hounsfield Unit score, and DEXA T-score in assessment of bone mineral density. J Clin Neurosci. 2024;126:63–67.

27. Yin H, Lin W, Xie F, et al. MRI-based vertebral bone quality score for osteoporosis screening based on different osteoporotic diagnostic criteria using DXA and QCT. Calcif Tissue Int. 2023;113(4):383–392.

28. Xu TT, Huang XY, Jiang YW. Efficacy of two opportunistic methods for screening osteoporosis in lumbar spine surgery patients. Eur Spine J. 2023;32(11):3912–3918.

29. Pennington Z, Ehresman J, Lubelski D, et al. Assessing underlying bone quality in spine surgery patients: a narrative review of dual-energy X-ray absorptiometry (DXA) and alternatives. Spine J. 2021;21(2):321–331.

30. Li W, Zhu H, Hua Z, et al. (2023). Vertebral bone quality score as a predictor of pedicle screw loosening following surgery for degenerative lumbar disease. Spine. 2023;48(23):1635–1641.

31. Gruenewald LD, Koch V, Martin SS, et al. Diagnostic accuracy of quantitative dual-energy CT-based volumetric bone mineral density assessment for the prediction of osteoporosis-associated fractures. Eur Radiol. 2022;32(5):3076–3084.

32. Van Hedent S, Su KH, Jordan DW, et al. Improving bone mineral density assessment using spectral detector CT. J Clin Densitom. 2019;22(3):374–381.

33. Conversano F, Franchini R, Greco A, et al. A novel ultrasound methodology for estimating spine mineral density. Ultrasound Med Biol. 2015;41(1):281–300.

34. Messina C, Fusco S, Gazzotti S, et al. DXA beyond bone mineral density and the REMS technique: new insights for current radiologists practice. La Radiologia Medica. 2024;129(8):1224–1240.

From UCI Health in Orange County, California.

Treatment for Osteoporosis

Mathematically, density is defined by mass divided by volume. It is a critical factor in the context of osteoporosis—a quantitative disease in which patients have low bone density. Osteoporosis can increase patients’ risk of fragility fractures and lead to a decreased quality of life (Figure). One way of preventing osteoporosis is by achieving and maintaining a healthy peak bone mass. Patients can improve their bone density through various interventions including good nutrition (with an adequate intake of calcium, phosphorus, and vitamin D), regular exercise, avoidance

Risk factors for developing osteoporosis include age (older patients), gender (females), race (Caucasians and Asians), a positive family history, body habitus (thin patients), and menopause. In addition, there are some medications (eg, anti-seizure medications), gastrointestinal conditions, and endocrine disorders that may contribute to the development of osteoporosis. Bone mineral density is most commonly measured by dual energy x-ray absorptiometry (DEXA) at the lumbar spine (L1-4) and hips. This

Yu-Po Lee, MD

osteoporosis is defined as a T-score ≤ -2.5. In patients who are osteopenic or osteoporotic, it is recommended that pharmacotherapy be started to maintain bone density.

When a patient has been diagnosed with osteoporosis, many physicians begin treatment by ensuring that patients are taking an adequate amount of calcium and vitamin D. Studies show a beneficial effect of vitamin D and calcium supplementation in the prevention of fractures.1-3 Women between the ages of 19 and 50 years should take 1,000 mg of calcium per day. Women aged 51 years or older should take 1,200 mg per day. Women aged 19 to 70 years should take 600 IU of vitamin D daily. Women older than 70 years should take 800 IU of vitamin D daily. Postmenopausal women with osteopenia or osteoporosis should take 1200 mg of calcium and 800 IU of vitamin D daily.1-3

The next tier of pharmacologic treatment in osteoporosis includes medications such as calcitonin, raloxifene, bisphosphonates, and aminobisphosphonate. Bisphosphonates and aminobisphosphonates are the drugs of choice for preventing and treating osteoporosis. Bisphosphonates (clodronate, etidronate, tiludronate) work by binding to hydroxyapatite and inhibiting bone resorption by blocking osteoclast action. 4-5 The aminobisphophonates (pamidronate, alendronate, risedronate, ibandronate, and zoledronic acid) are more potent than the simple bisphosphonates.4-5 Several studies show that the bisphosphonates and the aminobisphosphonates effectively increase bone mineral density and reduce the risk of hip and spine fractures.4-7 Of note, osteonecrosis

of the jaw has been documented as a rare side effect in patients receiving intravenous pamidronate, zoledronic acid, and, less frequently, oral bisphosphonates.6-7 Raloxifene and calcitonin salmon are alternatives for patients who cannot take bisphosphonates because of contraindications or adverse effects. Given its relatively weak anti-fracture efficacy, calcitonin is generally not considered as first-line therapy for treatment of osteoporosis.

Teriparatide (Forteo), a recombinant parathyroid hormone (PTH) fragment, increases bone mineral density. PTH increases renal calcium reabsorption, enhances intestinal calcium absorption via its effect on 1-hydroxylation of 25(OH)D, and increases bone remodeling. 8-9 The net effect of PTH on skeletal architecture depends on the pattern of exposure. Continuous secretion of PTH decreases bone mass, especially cortical bone. However, intermittent administration of exogenous PTH increases bone mass. Several clinical studies have shown a significant benefit of intermittent subcutaneous PTH on BMD and fracture risk. 8-9

Treatment with Forteo can be particularly helpful for patients at risk for vertebral or hip fractures because Forteo has a greater impact on trabecular bone formation. 8-9 In a prospective randomized study by Kendler et al, the authors compared Forteo to Risedronate.10 The authors found that the risk of new vertebral and clinical fractures was significantly lower in patients receiving Forteo than those receiving Risedronate. To avoid bone loss after stopping Forteo treatment, it needs to be followed with an-

tiresorptive treatment. The latest European International Osteoporosis Foundation and European Society for Clinical and Economic Evaluation of Osteoporosis and Osteoarthritis guidelines recommend the use of anabolic treatment first line for patients with very high fracture risk. 8

A newer osteoporosis medication is Tymlos (abaloparatide). Tymlos is a recombinant PTH analog that is similar to Forteo. It is injected subcutaneously and has similar potential side effects to Forteo. A meta-analysis of 8 studies by Xu et al showed that Tymlos has a protective effect on women with postmenopausal osteoporosis. It reduces the risk for vertebral fractures and increases hip and lumbar spine bone mineral density.11 In a study by Miller et al, the authors compare Tymlos to a placebo in a prospective, randomized study evaluating postmenopausal women with osteoporosis.12 The authors found that new vertebral fractures occurred in 0.58% of participants in the abaloparatide group and in 4.22% of those in the placebo group. There was also a group that received Forteo. In the Forteo group, new morphometric vertebral fractures occurred in 0.84%. The incidence of hypercalcemia was lower with Tymlos (3.4%) vs Forteo (6.4%).

Two other newer medications include denosumab (Prolia) and romosozumab (Xgeva). Both of these medications are monoclonal antibodies that have an antiresorptive effect on bone. Prolia is a monoclonal antibody that binds the cytokine RANKL (receptor activator of NFκ B ligand). This has the effect of inhibiting osteoclast maturation, function, and survival. In a

study by Cummings et al, the authors compared the effectiveness of Prolia versus a placebo group in preventing new fractures.13 New fracture risk in the Prolia group was 2.3% versus 7.2% in the placebo group. This signifies a decrease of 68% in the Prolia

Figure. Lateral radiograph of a L2 compression fracture.

group versus the placebo group. Xgeva is a monoclonal antibody against sclerostin, a natural inhibitor of the Wnt signaling pathway. In a study by Saag et al, the authors compared the efficacy of Xgeva versus oral alendronate in preventing new fractures.14 In this study, Xgeva was given subcutaneously for 12 months followed by oral alendronate for 12 months. The control group was given 12 months of oral alendronate followed by oral alendronate for another 12 months. After 24 months, the authors noted a 48% lower risk of new vertebral fractures in the romosozumab-to-alendronate group (6.2%) than in the alendronate-to-alendronate group (11.9%). The risk of nonvertebral

References

1. Chapuy MC, Arlot ME, Duboeuf F, et al. Vitamin D3 and calcium to prevent hip fractures in the elderly women. N Engl J Med. 1992;327(23):1637–1642.

2. Dawson-Hughes B, Harris SS, Krall EA, Dallal GE. Effect of calcium and vitamin D supplementation on bone density in men and women 65 years of age or older. N Engl J Med. 1997;337(10):670–676

3. Trivedi DP, Doll R, Khaw KT. Effect of four monthly oral vitamin D3 (cholecalciferol) supplementation on fractures and mortality in men and women living in the community: randomised double blind controlled trial. BMJ. 2003;326(7387):469.

4. Drake MT, Clarke BL, Khosla S. Bisphosphonates: mechanism of action and role in clinical practice. Mayo Clin Proc. 2008;83(9):1032-1045.

5. Kavanagh KL, Guo K, Dunford JE, et al. The molecular mechanism of nitrogen-containing bisphosphonates as antiosteoporosis drugs. Proc Natl Acad Sci U S A . 2006;103(20):7829–7834.

fractures was lower by 19% in the romosozumab-to-alendronate group than in the alendronate-to-alendronate group and the risk of hip fracture was lower by 38%. These findings suggest that Xgeva may have greater efficacy in reducing the risk of new vertebral, nonvertebral, and hip fractures compared to alendronate.

In conclusion, a wide range of pharmacologic options are now available for the treatment of osteoporosis, each with its own unique set of risks and benefits. As the population continues to age, the prevalence of osteoporosis is expected to rise, making it increasingly important for physicians to stay informed about the latest treatment options. l

6. Cremers SC, Pillai G, Papapoulos SE. Pharmacokinetics/pharmacodynamics of bisphosphonates: use for optimisation of intermittent therapy for osteoporosis. Clin Pharmacokinet . 2005;44(6):551–570.

7. Reid IR, Brown JP, Burckhardt P, et al. Intravenous zoledronic acid in postmenopausal women with low bone mineral density. N Engl J Med. 2002;346(9):653–661.

8. Hauser B, Alonso N, Riches PL. Review of current real-world experience with teriparatide as treatment of osteoporosis in different patient groups. J Clin Med. 2021;10(7):1403.

9. Neer RM, Arnaud CD, Zanchetta JR, et al. Effect of parathyroid hormone (1-34) on fractures and bone mineral density in postmenopausal women with osteoporosis. N Engl J Med. 2001;344:1434–1441.

10. Kendler DL, Marin F, Zerbini CAF, et al. Effects of teriparatide and risedronate on new fractures in post-menopausal women with severe osteoporosis (VERO): a multicentre, double-blind, double-dummy, randomised controlled trial. Lancet . 2018;391:230–240.

11. Xu F, Wang Y, Zhu X. The safety and efficacy of abaloparatide on postmenopausal osteoporosis: a systematic review and meta-analysis. Clin Ther. 2024;46(3):267-274.

12. Miller PD, Hattersley G, Riis BJ, et al; ACTIVE Study Investigators. Effect of abaloparatide vs placebo on new vertebral fractures in postmenopausal women with osteoporosis: a randomized clinical trial. JAMA . 2016;316(7):722-733.

13. Cummings SR, San Martin J, McClung MR, et al; FREEDOM Trial. Denosumab for prevention of fractures in postmenopausal women with osteoporosis. N Engl J Med. 2009;361(8):756-765.

14. Saag KG, Petersen J, Brandi ML, et al. Romosozumab or Alendronate for fracture prevention in women with osteoporosis. N Engl J Med. 2017;377(15):1417-1427.

From the Department of Orthopaedic Surgery at Rush University Medical Center in Chicago, Illinois.

Preoperative Malnutrition in Spine Surgery

With the increasing proportion of elderly individuals in the population and associated comorbidities, there has been increased awareness among spine surgeons in patient selection and perioperative management of modifiable risk factors. One such factor, preoperative malnutrition, has been estimated to have a prevalence as high as 50% in patients undergoing spine surgery.1-4 Additionally, preoperative malnutrition has been associated with adverse outcomes including wound complications, surgical site infections, pseudoarthrosis, increased length of hospital stay and unplanned readmissions.1,2,5-10 Standardized nutritional scoring systems and laboratory testing are essential to assess adequate nutritional status. 9,11-14 In patients with malnutrition, appropriate perioperative nutritional support and diet management should be employed to optimize surgical outcomes.

Pathophysiology and Etiology

According to the World Health Organization, malnutrition refers to deficiencies as well as excesses of nutrition related to obesity and diet-related noncommunicable diseases (heart disease, stroke, and diabetes).15 These conditions are associated with altered metabolism, chronic inflammation, gut dysfunction, and deficiencies of vital micronutrients.16-18 Additionally, as immune

cells do not possess significant energy stores, they are heavily reliant on uptake of nutrients from the environment to function appropriately.19,20 As a result, malnutrition leads to the inhibition of regulatory T-cell proliferation leading to decreased cytokine production, therefore limiting the ability to mount an immune response and prevent infections.19,20 Two conditions closely associated with malnutrition—diabetes and obesity—have rapidly risen in the Unites States, with an estimated prevalence >30%. 21,22 Consequently, there has been a corresponding increase in the number of these patients undergoing spine surgery, as both conditions are associated with the development of degenerative diseases. 22 Furthermore, many nutritional deficiencies are secondary to diseases related to decreased appetite, gut absorption, and metabolic imbalances including psychiatric disorders, inflammatory bowel disease, and neoplastic processes.11,23 Often, the etiology of malnutrition is multifaceted in nature and requires a comprehensive evaluation by clinicians.

Diagnosis and Evaluation

Preoperative evaluation of a patient’s nutritional status should begin with an appro -

Gregory Lopez, MD

Neil Mohile, MD

priate history and physical examination to assess any dramatic weight changes, muscle loss or gain, nutritional intake level, BMI, and associated acute or chronic diseases.11,12,14 Anthropometric measurements are commonly used in the literature to indicate undernutrition. In men, a calf muscle circumference of less than 31 cm and an arm muscle circumference of less than 22 cm are considered signs of undernutrition. Additionally, a measurement below 60% of the standard circumference for a given sex suggests severe malnutrition. 24,25

However, laboratory testing has been more substantiated in the literature to diagnose malnutrition, with the most common definitions as follows: serum total lymphocyte <1,500/mm 3 and serum albumin concentration <3.5 g/dL. 26-28 Low serum prealbumin <20 mg/dL and serum transferrin levels <200 mg/dL have been similarly described. 5,14,29,30 Albumin, prealbumin and transferrin are visceral proteins that are sensitive indicators of any nutritional changes. Although albumin, with a half-life of 20 days, has traditionally been regarded as the standard for assessing nutritional status, its levels can fluctuate in patients with renal disease, leading to variability in its accuracy. 5 In contrast, prealbumin is produced predominantly in the liver and detects acute changes of protein/ caloric nutrition with a half-life of 1.9 days. 5 Additionally, vitamin levels in high-risk patients and hemoglobin A1c in diabetic patients should be obtained to assess the severity of the respective diseases. Lastly, standardized screening tools are used to define malnutrition. The Rain -

ey-MacDonald Nutritional Index (RMNI) is often employed and calculated as follows:

RMNI = (1.2 x serum albumin) + (0.013 x serum transferrin) – 6.43

A zero or negative value suggests malnutrition. 31,32 Various additional scoring systems and questionnaires are available, including the Nutritional Risk Score and Mini Nutritional Assessment. 33,34

Malnutrition Outcomes in Spine Surgery

Adverse outcomes in the setting of spine surgery in patients with malnutrition is well-reported in the literature. Bohl et al performed a retrospective review of data collected by the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP), which included 4,310 patients undergoing posterior lumbar spine fusion to investigate an association between preoperative hypoalbuminemia (as defined as <3.5 g/dL) and complications. The study found that patients with hypoalbuminemia have a higher risk of wound dehiscence (1.5% vs 0.2%, p = 0.006), surgical site infections (5.4% vs 1.7%, p = 0.010), urinary tract infections (5.4% vs 1.5%, p = 0.005), and 30-day unplanned admissions (11.7% vs 5.4%, p < 0.001).7 Furthermore, the study noted that the prevalence of hypoalbuminemia was closely associated with increasing age, insulin-dependent diabetes, and BMI.7

Puvanesarajah et al conducted a retrospective review of Medicare data from 2005 to 2012, which included 148,238 patients

undergoing elective 1- or 2-level posterior lumbar fusion. 8 The study noted similar results, as preoperative malnutrition was found to be predictive of increased infection rates, wound dehiscence, LOS, and 30-day readmissions. 8 Similar adverse outcomes have been noted in additional studies, including in patients undergoing other types of spine surgery, such as anterior cervical discectomy and fusions (ACDFs) and adult spinal deformity corrections.1,2,5,6,9,10 These adverse events are associated with increased healthcare costs. Blumberg et al found that for every decrease in albumin by 1 g/dL, there was an approximately $8,081 increase in treatment cost and a 3.7 day increase in length of stay. 35

Optimization and Treatment

In 2021, the Enhanced Recovery After Surgery (ERAS) Society provided a strong recommendation in favor of a preoperative nutritional assessment and supplementation in patients undergoing elective spine surgery.13 While there remains a paucity of literature evaluating whether modifying or optimizing preoperative nutritional status results in improved clinical outcomes, recent studies have supported this claim. Saleh et al conducted a randomized controlled trial in 103 patients undergoing lumbar spine surgery.36 The intervention group received nutritional supplementation (protein shake) twice daily from postoperative day 0 to 2 weeks postdischarge while the control group was instructed to continue regular

diets. Subgroup analysis of malnourished patients (defined as preoperative albumin <3.5 g/dL) who received protein shakes had lower rates of minor complications during admission (0.0% vs. 34.4%, p = 0.01) and lower rates of return to the operating room within 90 days (0.0% vs. 12.4%, p = 0.04). 36

Liquid oral nutritional supplements (ONS) are preferred to solids due to faster gastric emptying and therefore less impact on the caloric intake of actual meals.14 In literature

References

1. Adogwa O, Elsamadicy AA, Mehta AI, Cheng J, Bagley CA, Karikari IO. Preoperative nutritional status is an independent predictor of 30-day hospital readmission after elective spine surgery. Spine (Phila Pa 1976). 2016;41(17):1400-1404.

2. Elsamadicy AA, Havlik J, Reeves BC, et al. Effects of preoperative nutritional status on complications and readmissions after posterior lumbar decompression and fusion for spondylolisthesis: A propensity-score analysis. Clin Neurol Neurosurg. 2021;211:107017.

3. Phan K, Kim JS, Xu J, et al. Nutritional insufficiency as a predictor for adverse outcomes in adult spinal deformity surgery. Global Spine J. 2018;8(2):164-171.

4. Ehresman J, Ahmed AK, Schilling A, et al. Preoperative nutrition consults associated with decreased postoperative complication rate and decreased length of hospital stay after spine metastasis surgery. World Neurosurg. 2020;133:e173-e179.

5. Tempel Z, Grandhi R, Maserati M, et al. Prealbumin as a serum biomarker of impaired perioperative nutritional status and risk for surgical site infection after spine surgery. J Neurol Surg A Cent Eur Neurosurg. 2015;76(2):139-143.

6. Adogwa O, Martin JR, Huang K, et al. Preoperative serum albumin level as a predictor of postoperative complication after spine fusion. Spine (Phila Pa 1976). 2014;39(18):1513-1519.

outside the realm of spine surgery, a meta-analysis of 24 trials, including 2,387 adults, showed that ONS reduced overall mortality, particularly in undernourished elderly patients. 37 Other studies have found positive effects of ONS on body weight, energy/protein intake, and functional status. 38,39

Based on the current evidence, if a patient is found to be malnourished, an informed discussion with the patient regarding potentially delaying elective surgery until the

7. Bohl DD, Shen MR, Mayo BC, et al. Malnutrition predicts infectious and wound complications following posterior lumbar spinal fusion. Spine (Phila Pa 1976). 2016;41(21):1693-1699.

8. Puvanesarajah V, Jain A, Kebaish K, et al. Poor nutrition status and lumbar spine fusion surgery in the elderly: readmissions, complications, and mortality. Spine (Phila Pa 1976). 2017;42(13):979-983.

9. Bisson EF, Dimar J, Harrop JS, et al. Congress of Neurological Surgeons systematic review and evidence-based guidelines for perioperative spine: preoperative nutritional assessment. Neurosurgery. 2021;89(Suppl 1):S26-S32.

10. Reyes J, Katiyar P, Greisberg G, et al. Preoperative nutritional optimization for adult spinal deformity: review. Spine Deform. 2024;12(2):257-262.

11. Qureshi R, Rasool M, Puvanesarajah V, Hassanzadeh H. Perioperative nutritional optimization in spine surgery. Clin Spine Surg. 2018;31(3):103-107.

12. Cross MB, Yi PH, Thomas CF, Garcia J, Della Valle CJ. Evaluation of malnutrition in orthopaedic surgery. J Am Acad Orthop Surg. 2014;22(3):193-199.

13. Debono B, Wainwright TW, Wang MY, et al. Consensus statement for perioperative care in lumbar spinal fusion: Enhanced Recovery After Surgery (ERAS®) Society recommendations. Spine J. 2021;21(5):729-752.

14. Nieuwenhuizen WF, Weenen H, Rigby P, Hetherington MM. Older adults and patients in need of nutritional support: review of current treatment options and factors influencing nutritional intake. Clin Nutr. 2010;29(2):160-169.

15. Fact sheets - malnutrition [Internet]. World Health Organization; 2024 [cited 2024 Sept 7]. Available from: https://www.who.int/ news-room/fact-sheets/detail/malnutrition

16. Kong LC, Holmes BA, Cotillard A, et al. Dietary patterns differently associate with inflammation and gut microbiota in overweight and obese subjects. PLoS One . 2014;9(10):e109434.

17. Pereira-Santos M, Costa PR, Assis AM, Santos CA, Santos DB. Obesity and vitamin D deficiency: a systematic review and meta-analysis. Obes Rev. 2015;16(4):341-349.

18. Sánchez A, Rojas P, Basfi-Fer K, et al. Micronutrient deficiencies in morbidly obese women prior to bariatric surgery. Obes Surg. 2016;26(2):361-368.

19. Cohen S, Danzaki K, MacIver NJ. Nutritional effects on T-cell immunometabolism. Eur J Immunol. 2017;47(2):225-235.

20. Gerriets VA, MacIver NJ. Role of T cells in malnutrition and obesity. Front Immunol. 2014;5:379.

nutritional status is optimized is warranted. While additional research is needed to assess whether improving nutritional status improves outcomes following spine surgery, addressing malnutrition preoperatively remains a reasonable approach to potentially reduce the risk of complications.

Conclusion

Given the high prevalence of malnutrition in our population, careful attention must be placed

to assess patients’ nutritional status prior to surgery. Multiple tools, including laboratory tests and nutritional scoring systems, may be employed by spine surgeons in the diagnostic evaluation of these patients. In prioritizing nutrition in our patients, potential postoperative complications may be avoided. When malnutrition is detected, nutritional counseling should be administered, consisting of dietary advice, meal fortification and oral nutritional supplements in the preoperative setting. l

21. Flegal KM, Carroll MD, Ogden CL, Curtin LR. Prevalence and trends in obesity among US adults, 19992008. JAMA. 2010;303(3):235-241.

22. Moretti L, Medeiros LJ, Kunkalla K, Williams MD, Singh RR, Vega F. N-terminal PAX8 polyclonal antibody shows cross-reactivity with N-terminal region of PAX5 and is responsible for reports of PAX8 positivity in malignant lymphomas. Mod Pathol. 2012;25(2):231-236.

23. Damms-Machado A, Weser G, Bischoff SC. Micronutrient deficiency in obese subjects undergoing low calorie diet. Nutr J. 2012;11:34.

24. Pratt WB, Veitch JM, McRoberts RL. Nutritional status of orthopedic patients with surgical complications. Clin Orthop Relat Res . 1981;(155):81-84.

25. Murphy MC, Brooks CN, New SA, Lumbers ML. The use of the Mini-Nutritional Assessment (MNA) tool in elderly orthopaedic patients. Eur J Clin Nutr. 2000;54(7):555-562.

26. Jaberi FM, Parvizi J, Haytmanek CT, Joshi A, Purtill J. Procrastination of wound drainage and malnutrition affect the outcome of joint arthroplasty. Clin Orthop Relat Res . 2008;466(6):1368-1371.

27. Greene KA, Wilde AH, Stulberg BN. Preoperative nutritional status of total joint patients. Relationship to postoperative wound complications.

J Arthroplasty. 1991;6(4):321-325.

28. Puskarich CL, Nelson CL, Nusbickel FR, Stroope HF. The use of two nutritional indicators in identifying long bone fracture patients who do and do not develop infections. J Orthop Res . 1990;8(6):799-803.

29. Beiner JM, Grauer J, Kwon BK, Vaccaro AR. Postoperative wound infections of the spine. Neurosurg Focus . 2003;15(3):E14.

30. McPhee IB, Williams RP, Swanson CE. Factors influencing wound healing after surgery for metastatic disease of the spine. Spine (Phila Pa 1976). 1998;23(6):726-732; discussion 732-733.

31. Font-Vizcarra L, Lozano L, Ríos J, Forga MT, Soriano A. Preoperative nutritional status and post-operative infection in total knee replacements: a prospective study of 213 patients. Int J Artif Organs . 2011;34(9):876-881.

32. Rainey-Macdonald CG, Holliday RL, Wells GA, Donner AP. Validity of a two-variable nutritional index for use in selecting candidates for nutritional support. JPEN J Parenter Enteral Nutr. 1983;7(1):15-20.

33. Kondrup J, Rasmussen HH, Hamberg O, Stanga Z; Ad Hoc ESPEN Working Group. Nutritional risk screening (NRS 2002): a new method based on an analysis of controlled clinical trials. Clin Nutr. 2003;22(3):321-336.

34. Weimann A, Braga M, Harsanyi L, et al; ESPEN (European Society for Parenteral and Enteral Nutrition). ESPEN Guidelines on Enteral Nutrition: Surgery including organ transplantation. Clin Nutr. 2006;25(2):224-244.

35. Blumberg TJ, Woelber E, Bellabarba C, Bransford R, Spina N. Predictors of increased cost and length of stay in the treatment of postoperative spine surgical site infection. Spine J. 2018;18(2):300-306.

36. Saleh H, Williamson TK, Passias PG. Perioperative nutritional supplementation decreases wound healing complications following elective lumbar spine surgery: a randomized controlled trial. Spine (Phila Pa 1976). 2023;48(6):376-383.

37. Milne AC, Avenell A, Potter J. Oral protein and energy supplementation in older people: a systematic review of randomized trials. Nestle Nutr Workshop Ser Clin Perform Programme . 2005;10:103-125.

38. Stratton RJ, Elia M. Encouraging appropriate, evidence-based use of oral nutritional supplements. Proc Nutr Soc . 2010;69(4):477-487.

39. Potter JM, Roberts MA, McColl JH, Reilly JJ. Protein energy supplements in unwell elderly patients—a randomized controlled trial. JPEN J Parenter Enteral Nutr. 2001;25(6):323-329.

From DISC Sports and Spine Center in Newport Beach, California.

Framework for Mentorship of Spine Surgeons in Early Practice

Mentorship in surgical specialties has a long history that predates the modern medical era. Prior to the advent of formal medical training programs in the 1890s, surgeons who were not self-taught spent time as apprentices under an experienced surgeon. The first formal surgical fellowship program is attributed to Dr. William Stewart Halsted of Johns Hopkins Hospital. In 1889, Halsted introduced a residency training system that included a structured approach to surgical education, and that system evolved into what we recognize today as fellowship programs.1

Training programs foster an ideal environment for mentorship as residents and fellows typically spend several months with one or more senior surgeons in the office and in the operating room. The long hours spent in cases, teaching conferences, and seeing patients are inherently ripe for relationship building. Ironically, it is upon graduation, after many years of intensive training, that young surgeons find themselves more in need of mentorship than at any other point in their career. 2,3 As young surgeons enter independent practice, decision-making responsibility becomes all their own, without the safety net of a structured program. While newly minted spine surgeons may succeed without mentorship, the complex, high-risk nature of the field makes this chal-

lenging. Spine surgeons are frequently faced with clinical and non-clinical dilemmas they have not encountered during training. In many of these scenarios, textbooks and the literature do not provide clear guidance. Thus, quality mentorship can dramatically improve a young spine surgeon’s procedural comfort, complication management, and confidence during these formative years. In addition, mentors can offer valuable insights into the business and administrative aspects of running a practice, which often are not covered in formal training programs.

Responsibilities of Mentors and Mentees

Mentorship is distinct from serving as a role model. Many surgeons have role models after which they pattern their clinical and non-clinical professional endeavors. Relationships between young surgeons and a role model are typically passive and observational, whereas mentorship involves an active, two-way exchange of information. This requires both mentor and mentee to assume certain duties in order to maximize the value of the relationship.

The best mentors take an active interest in the personal and professional success of the mentee. Mentors should make an early effort to establish an open, honest line of communication with the mentee and to make

Brandon Hirsch, MD

their preferences about mode and timing of discussions clear. An aspiring mentee may be hesitant to pursue mentorship with accomplished senior surgeons whom they perceive to have little or no availability in their schedule. Mentors are encouraged to share their personal stories of development early in the relationship. This both sets the stage for transparent discussion and provides an opportunity for mentor and mentee to find common ground. Seeking out open-ended discussion about the mentee’s goals and challenges further enhances rapport.4 Lastly, mentors should consider their proficiency in providing constructive feedback, as this is a critical component of professional development for mentees. Models that help facilitate this often-challenging responsibility have been well studied in medicine. 5

Mentees also have obligations to ensure successful mentorship. Mentees benefit from being proactive in the process of seeking a mentor to ensure their values and personality type are a good fit. Ideally, mentees would seek out mentors with whom they share common clinical or research interests. Mentees should give careful thought as to what specific information or guidance they are seeking and be capable of communicating these needs clearly. Mentees must understand that desirable mentors typically have demanding schedules that must be planned well in advance. Along these lines, it is essential that mentees are reliable with regard to deadlines and attending planned meetings. Mentees must also seek and be receptive to constructive feedback in order to maximize their personal and professional growth.

Benefits of Mentorship

Mentorship in spine surgery provides significant benefits for both mentors and mentees. Mentees receive valuable career guidance and support while navigating the challenges of a demanding field. They gain access to the mentor's thought process in the face of clinical uncertainty, refine specialized surgical techniques, and gain business knowledge. Additionally, mentees may receive exposure to leadership positions in specialty societies and may be given opportunities to advance their academic career or become involved with industry.

For mentors, the experience of teaching and guiding younger surgeons brings personal fulfillment and satisfaction. Mentorship helps them keep up to date with the latest advancements, reinforces their own knowledge, and improves leadership and communication skills. By mentoring, they leave a lasting legacy, shaping the future standards of care in spine surgery. Mentorship also opens opportunities for collaborative

A senior spine surgeon guides a young surgeon learning a new surgical technique.

TRAINING

research, enhancing the mentor's impact on the field and contributing to the overall advancement of spine surgery practices. 6

Finding Opportunities for Mentorship

Practical opportunities for mentorship in spine surgery are numerous and can range from a simple email thread for case discussion to participation in formal multicenter research study groups. In some practice environments, regular weekly collaboration in the operating room with a senior partner is the norm and can serve as a tremendous opportunity for professional development. Those without an opportunity to scrub with senior partners might seek out traveling fellowships or live case observation facilitated by industry, as most instructors involved in these programs are enthusiastic about teaching. The majority of spine specialty societies are eager to involve young surgeons in committee work, which is often led by senior surgeons with a proclivity toward mentorship. Alumni networks from residency or fellowship programs also serve as phenomenal resources for identifying mentors in practice. On a local level, hospital peer review or medical executive committee

References

1. Kerr B, O’Leary JP. The training of the surgeon: Dr. Halsted’s greatest legacy. Am Surg. 1999;65:1101–1102.

2. Dvorak MF, Collins JB, Murnaghan L, et al. Confidence in spine training among senior neurosurgical and orthopedic residents. Spine (Phila Pa 1976). 2006;31:831–837.

3. Bateman AH, Larouche J, Goldstein CL, et al. The importance of determining trainee

involvement is likely to help young surgeons meet and interact with mentors in their communities. As social media’s role continues to grow in our profession, even online platforms such as LinkedIn can provide exposure to potential mentors that would otherwise not be possible.

Conclusion

Mentorship in spine surgery goes far beyond simply teaching surgical technique; it serves as a guide to the potentially turbulent transition to independent practice and helps mold high quality clinicians ready to meet the spine care needs of their community. Mentorship is a dynamic process that requires commitment and engagement by both parties. This exchange benefits the mentor, the mentee, and patients, ensuring that valuable knowledge is passed down and applied in new ways. Fortunately, ample and varied opportunities for mentorship exist on the local, national, and even international level for those willing to seek them out. As spine surgery continues to evolve in the context of a challenging healthcare landscape, mentorship of young surgeons will remain critical to the ongoing advancement of our field. l

perspectives on procedural competencies during spine surgery clinical fellowship. Global Spine J. 2019;9(1):18–24.

4. Mulcahey MK, Waterman BR, Hart R, Daniels AH. The role of mentoring in the development of successful orthopaedic surgeons. J Am Acad Orthop Surg. 2018;26(13):463–471.

5. Sargeant J, Lockyer JM, Mann K, et

al. The R2C2 model in residency education: how does it foster coaching and promote feedback use? Acad Med. 2018;93(7):1055–1063.

6. Sundar SJ, Whiting BB, Lubelski D, et al. Key factors for enhancing academic productivity and fostering mentorship in spine research: the Cleveland Clinic Center for Spine Health approach to sustaining success. Spine J. 2024;24:14–20.

From the 1Department of Orthopaedic Surgery and 2 Department of Neurological Surgery, both at UC Davis Health in Sacramento, California.

Ambulatory Surgery Center Development in an Academic Medical Center—Is It Possible?

The Ambulatory Surgery Center Association defines ambulatory surgery centers, or ASCs, as “modern healthcare facilities focused on providing same-day surgical care, including diagnostic and preventive procedures.” 1 Indeed, ASCs have transformed the outpatient surgical experience for many millions of Americans by providing them with a patient-centric, efficient, and cost-conscious alternative to overnight hospital-based outpatient procedures. Since the advent of ASCs (first established in 1970 in Phoenix, AZ), there has been substantial evidence supporting that spine procedures can be successfully completed with high-quality care and positive patient outcomes.1 The benefits of ASCs specifically for surgeons are incremental; they allow surgeons the ability to perform specific procedures more safely, efficiently, and conveniently compared to hospital-based operating rooms.

The Agency for Healthcare Research and Quality states that nearly 75% of all surgeries in the United States are done in an ambulatory setting, often at an ASC. 2 As the concept gained traction and with broad partnerships between management companies, physicians (surgeons and anesthesiologists), and financial

entities, ASCs are now the preferred site of service for many spine procedures, including decompressions, endoscopic cases, and select fusions (eg, anterior cervical discectomy and fusion). It is reasonable to expect that the patient and surgeon benefits, quality control, and cost-consciousness in the private sector make ASCs attractive options for academic medical centers that traditionally provide quaternary care to a sicker patient population. By definition, an academic ASC is defined as an ASC that operates under the management of an educational institute and is located within or outside the institutional buildings. A hospital outpatient department (HOPD) is typically owned by a hospital and is managed by its management team. The physical location of the HOPD could be within a 35-mile radius of the main hospital.

The question is, can the benefits of privately owned ASCs translate to academic medical centers? What needs to be done differently in an academic ASC to achieve similar success?

Safdar N. Khan, MD1

Hania Shazad, MD1

Richard L. Price, MD, PhD2

What are the differences between non-academic vs academic ASCs?

Nonacademic ASCs are typically managed by externally hired teams with physician board oversight, promoting cost-conscious decision-making and fostering culture change through physician ownership. In contrast, academic ASCs, which can be ASCs or HOPDs, are under hospital administration jurisdiction, require inspections from the Joint Commission on Accreditation of Healthcare Organizations, and potentially need accreditation if trainees are involved. Medicare/Medicaid payments can also differ between ASC and HOPD entities. Table 1 outlines some of these differences.

What factors do academic institutions need to keep in mind when opening an ASC?

Culture Shifts

The quaternary-level care model of traditional academic medical centers often leads to inefficiencies and restrictions in terms of access to cost and time-conscious care. In an environment that will only be successful if there is protocolized care, procedural fluidity, and rapid turnover, staffing models (physician, nursing, operating room teams) will need to include individuals with a highly flexible mindset. Constant communication is key to rapid corrections of any issues that may lead to inefficiency.

accreditation from an academic entity if trainees involved

Abbreviations: ASC, ambulatory surgical center; HOPD, hospital outpatient department; JCAHO, Joint Commission on Accreditation of Healthcare Organizations; NA, not applicable.

Table 1. Differences Between Nonacademic and Academic ASCs

Partnerships and Joint Ventures

Academic medical centers may collaborate with private practices, healthcare systems, or investment groups to form ASCs. These joint ventures allow academic centers to leverage external expertise and investment while expanding their outpatient capabilities. The Johns Hopkins Model (JHM) is an excellent example to study. 3 Its Surgery Coordinating Council (SCC) was established to integrate its eight ASCs with its HOPDs. With culture change, partnerships, and a constant cycle of improvement, they have created a superb model of academic center ASC integration. Some factors in their success have been (1) promoting multidisciplinary interactions among JHM-employed and non–JHM-employed physicians; (2) setting approaches for ASC quality and safety efforts; and (3) constantly identifying, implementing, and evaluating best practices.

Focus on Efficiency and Innovation

ASCs allow academic centers to offload routine or less complex surgical cases from traditional hospital settings, which are often more expensive. This separation increases the efficiency of hospitals for complex surgeries and allows the ASC to specialize in high-volume, lower-risk procedures. The ability to invest in enabling technologies creates an exciting set of principles, including surgery-specific operating rooms—outfitted at the ASC to only take care of specific service lines. We believe the ASPIRE concept (Table 2) allows academic centers to create success for spinal procedures in the ASC environment.

Training and Research

Since academic centers are teaching institutions, having an ASC can offer medical residents and students exposure to outpatient surgeries, giving them hands-on experience.

A Anesthesia ERAS protocols

S Spine-specific operating rooms (outfitted with enabling technologies to perform high throughput cases)

P Patient selection

I Innovation (Augmented reality, robotics, personalized implants, innovation in negotiation with implant companies)

R Reproducibility in resource use (a team approach focused on data collection and outcomes accountability)

E Efficiency (time and technique base)

Abbreviation: ERAS, enhanced recovery after surgery.

Table 2. ASPIRE Concept.

References

MEDICAL PRACTICE

It also provides a setting to explore new surgical techniques and technologies in a controlled, cost-effective environment. Fellows who are being recruited to an ASC-heavy practice can get a head start on managing their training and creating their practice.

Improved Patient Experience

ASCs can streamline the patient experience with shorter wait times, lower costs, and a less intimidating atmosphere compared to large hospitals. This aligns with academic institutions' missions to advance patient-centered care.

Financial Incentives

Operating an ASC can be a more profit-

1. Ambulatory Surgery Center Association. What is an ASC? https://www.ascassociation.org/asca/about-ascs/surgery-centers

able venture compared to a full-service hospital, due to lower overhead costs and better insurance reimbursement rates for outpatient services. Academic centers often pursue these ventures to help offset other more costly areas of care.

Summary

Academic centers can and often do create ASCs. These centers, which are designed for outpatient surgeries, allow academic institutions to expand their surgical services, improve patient care, and create a more efficient and cost-effective environment for certain procedures. The ASPIRE concept can guide spine-specific success in academic ASCs. l

2. Wier LM, Steiner CA, Owens PL. Surgeries in Hospital-Owned Outpatient Facilities, 2012 . HCUP Statistical Brief #188. Agency for Healthcare Research and Quality; 2015.

3. Ishii L, Pronovost PJ, Demski R, Wylie G, Zenilman M. A model for integrating ambulatory surgery centers into an academic health system using a novel ambulatory surgery coordinating council. Acad Med. 2016;91(6):803–6.