Vertebral Columns Summer_2026

Benefits of 3D Anatomical Modeling in Spine Surgery What Are the Modifiable and Protective Strategies to Mitigate Proximal Junctional Kyphosis and Failure in Adult Spinal Deformity Surgery Annular Repair After Microdiscectomy: Does It Prevent Reherniation?

Minimal Clinically Important Difference in Spine Surgery: Are We Using the Right Thresholds?

The Role of Preoperative Bone Optimization in Spine Surgery What Is the Ideal Mattress Type for Patients With Chronic Neck and Low Back Pain?

Second Victim Syndrome and Spine Surgeons: The Hidden Complication We Rarely Discuss Private Equity in Orthopedics and Spine Surgery: 10 Years Later

Vertebral

COLUMNS International Society for the Advancement of Spine Surgery

LARGE LANGUAGE MODELS IN SPINE SURGERY:

SUMMER 2026

DME in Cervical Spine Surgery: What Does the Evidence Say?

Useful Tool or Overhyped Assistant?

Summer 2026 Editor in Chief Kern Singh, MD Associate Editor Daniel K. Park, MD

EDITORIAL 3 Large Language Models in Spine Surgery: Useful Tool or

Editorial Board

8 DME in Cervical Spine Surgery: What Does the Evidence

Sravisht Iyer, MD

Overhyped Assistant?

CERVICAL SPINE

Say?

NEW TECHNOLOGY 13 Benefits of 3D Anatomical Modeling in Spine Surgery SPINAL DEFORMITIES 19 What Are the Modifiable and Protective Strategies to

Mitigate Proximal Junctional Kyphosis and Failure in Adult Spinal Deformity Surgery

PATIENT OUTCOMES 27 Annular Repair After Microdiscectomy: Does It Prevent Reherniation?

Brandon Hirsch, MD

Nathan J. Lee, MD Yu-Po Lee, MD Sheeraz Qureshi, MD, MBA Arash J. Sayari, MD Managing Editor Audrey Lusher Designer CavedwellerStudio.com

OUTCOME MEASURES 31 Minimal Clinically Important Difference in Spine Surgery: Are We Using the Right Thresholds?

BONE HEALTH 37 The Role of Preoperative Bone Optimization in Spine Surgery

EVIDENCE SUMMARY 41 What Is the Ideal Mattress Type for Patients With Chronic Neck and Low Back Pain?

PHYSICIAN HEALTH 43 Second Victim Syndrome and Spine Surgeons: The Hidden Complication We Rarely Discuss

PRACTICE MODELS 47 Private Equity in Orthopedics and Spine Surgery: 10 Years Later

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Vertebral Columns is published quarterly by the International Society for the Advancement of Spine Surgery. ©2026 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/

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EDITORIAL

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

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Large Language Models in Spine Surgery: Useful Tool or Overhyped Assistant?

Aimen A. Khan, BS

Would you upload your medical records to ChatGPT? In a recent national survey of U.S. adults, 77% of respondents said they are concerned about the privacy ramifications of sharing health information w ith artificial intelligence (AI). Despite these concerns, 41% report uploading personal medical information into an AI chatbot.1 As large language models (LLMs) become increasingly integrated into healthcare, their growing use by patients and physicians alike demands a closer examination. Tools such as Gemini, Claude, ChatGPT, and other models have showcased an ability to generate human-like text, synthesize and condense information into sizable portions, and answer questions as a personal assistant for a variety of tasks. As these technologies become increasingly accessible, the interest in analyzing their application to spine surgery continues to grow.

The question is not whether LLMs can be used in spine surger y, but where they provide meaningful value and where their limitations become clinically significant. W hile some view them as transformative technologies that will fundamentally change

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clinical practice, others see them as overhyped chatbots whose capabilities have been exaggerated.

What Are LLMs and How Do They Work?

LLMs are prediction engines, generating responses by identifying patterns in enormous amounts of text and predicting the next likely word in a sequence. This allows LLMs to present human-like language and flow. 2 However, vital recognition is that these systems do not truly understand the information they generate and are not producing answers through the thought process of a physician, but rather statistical relationships learned during training.

A defining limitation is “hallucination,” in which responses will sound highly convincing, even providing citations, while offering completely incorrect or fabricated information.

This distinction has also been demonstrated in benchmark studies, including evaluations that LLMs can achieve passing marks on standardized medical examinations such as the U.S. Medical Licensing Examination (USMLE).3 However, further analysis shows that

Maximillian Lee, BS

Noah A. Pogonitz, BS

Daniel K. Park, MD

Kern Singh, MD

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EDITORIAL

the score the LLM obtained is due to pattern recognition rather than clinical judgment and reasoning. Models have been shown to frequently struggle with scenarios that require multi-sequence decision-making.4 Even when the model provides a reasonable answer, it may be impossible for the user to determine whether the response is correct without verification or knowing the subject themselves. Accuracy is essential for a physician in each step of curating the patient’s treatment plan, and this significantly limits the level to which LLMs can be trusted in clinical settings.

Where Can LLMs Help?

Documentation and Workflow Efficiency The most immediate and practical application of LLMs in spine surgery is clinical documentation. Spine patients often have

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extensive medical histories, containing a plethora of clinical notes, specialist consultations, imaging, and records. Spine surgeons are routinely reviewing this information, which becomes time-consuming. LLMs carry the strength of synthesizing large amounts of text into summaries and identifying the relevant points for physicians more efficiently. However, these benefits should be interpreted with caution. Studies evaluating AI-generated documentation have identified inaccuracies in clinical notes, including removed findings and incorrect details, despite clear presentation. 5,6 Other AI tools, such as Microsoft Dragon Ambient Experience (DAX) Copilot (Microsoft Corporation, Redmond, WA), assist surgeons with clinic visits. DAX listens to patient-surgeon conversations and organizes discussions into cogent clinic notes. Surgeons can spend more quality time with patients without diverting attention to documentation. LLMs, therefore, currently function best as a drafting tool for notes, and they still require physician oversight.

Research and Academic Productivity LLMs have demonstrated utility in academic writing. They can assist in organizing manuscripts, refining language, and improving readability. In blinded evaluations, AI-generated abstracts have been difficult for reviewers to distinguish from human-written content, raising both opportunities and concerns regarding scientific communication. Scientific writing is often formulaic and without emotional language, mimicking the common language flow these models use.

Another major limitation is the generation

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EDITORIAL

of fabricated references by LLMs. In a study analyzing citations produced by ChatGPT, a substantial proportion was found to be entirely fabricated or contained significant inaccuracies.6 Analyses of published academic work have identified hallucinated references embedded w it h in accepted manuscripts, including papers presented at major conferences.7-9 Thus, LLMs are most effective for improving readability and checking grammar, not for acting as autonomous authors.

Patient Communication and Education Patient communication may also benefit. Explaining conditions such as lumbar stenosis, cervical myelopathy, or spondylolisthesis at a level that patients can easily visualize and understand is challenging. LLMs can generate simplified explanations that may improve patient education and facilitate discussions during clinic visits.10 Messages and calls received by patients often contain questions on medications, surgery discussions, pain management, and administrative tasks. While LLMs can be a strong tool in drafting messages and curating response templates for common questions, LLMs cannot replicate the clinical judgment required in spine surgery.

In a study evaluating LLMs for minimally invasive spine surgery triage, agreement between LLM recommendations and expert-derived procedural categories was only slight to fair. Although the models were better at distinguishing surgical from nonsurgical cases, they demonstrated substantially lower agreement when selecting

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specific procedures, leading the authors to conclude that procedure selection should remain expert-led.11 If used to make surgical recommendations, LLMs must be tailored to the surgeon. While literature on procedure results and efficacy exist, these conclusions only reflect the surgeons involved in each study. A surgeon may achieve better results than reported in the literature or may be more skilled with a particular fusion technique over other methods and thus may utilize certain procedures more frequently. This critical nuance reinforces the importance of viewing AI and LLMs as supplements for general patient education rather than substitutes for individualized patient counseling.

Can LLMs Make Spine Surgery Decisions?

At this junction, the enthusiasm for AI often exceeds the available evidence. While studies have shown that LLMs can generate differential diagnoses and general management frameworks, their accuracy is inconsistent, particularly in complex cases.4 LLMs may be able to associate and produce a differential diagnosis and review treatment options; however, there is a difference between generating possibilities and making decisions.

In spine-specific contexts, evaluations have demonstrated that LLMs provide broad recommendations but lack the specificity required for surgical decision-making.11 Comparative studies between orthopedic surgeons and AI models further highlight this limitation, with AI systems underperforming in nuanced clinical scenarios.12 Additionally, one of the central components of a patient’s

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EDITORIAL

medical record for making surgical decisions is through imaging. However, LLMs are unable to integrate imaging, and combining this limitation with the risk of hallucinations highlights shortcomings in their use as independent decision-support tools.

Ethical, Legal, and Regulatory Considerations The integration of LLMs into clinical practice introduces the discussion of ethical and regulatory challenges. Because LLMs may process sensitive patient information, compliance w it h t he Healt h Insurance Portability and Accountability Act (HIPAA) remains an important consideration. The Health Information Technolog y for Economic and Clinical Health (HITECH) Act further strengthened HIPAA enforcement by increasing penalties for data breaches and expanding accountability for organizations handling electronic health records. Physicians should avoid entering protected health information (PHI) into publicly available AI platforms unless appropriate approvals are in place. From a legal standpoint, liability also remains an evolving issue. While LLMs may assist with documentation, communication, or information retrieval, responsibility for clinical decisions ultimately remains with the treating physician. In response to this concern, many healthcare systems are exploring institution-specific model implementations.

While privacy concerns receive significant attention, they are not the only challenges associated with LLM adoption in medicine.

Medical decision-making must be viewed

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as unique intellectual propert y despite standardized training through residency accreditation and board examinations.

Surgeons may incorporate guidelines and treatment algorithms into their practice, but real-world patients do not always fit into these algorithmic schemes. Thus, as they obtain more experience, surgeons develop a unique, proprietary approach to evaluating and treating patients based on their training, the literature, their skillset, and their own experience. If an LLM learns to make clinical decisions, it must learn from the experienced surgeons who develop and train the models. AI and LLMs in their current form may appear to be benign adjuncts in medicine today, but tomorrow, they may be at the intersection of legal battles regarding intellectual property rights. Policy and legal guardrails must be placed on this topic before making additional developments.

Practical Integration and Looking Ahead The most realistic role for LLMs in spine surgery is as an assistive technology rather than an autonomous decision-maker. Current applications are best suited for tasks such as documentation, medical record summarization, patient education, research support, and work reliant on pattern recognition.

Looking ahead, future models may become more useful as they incorporate imaging data, structured clinical information, and specialty-specific training. Integration with electronic health records may allow LLMs to retrieve and organize relevant patient information more efficiently, reducing admin-

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EDITORIAL

istrative burden and streamlining clinical workflows. Advances in multimodal AI may also enable future systems to incorporate imaging, laboratory data, and clinical notes into a single platform.

The successful implementation of LLMs will depend on maintaining transparency, protecting patient privacy, and ensuring that physician judgment remains the central driver in the patient’s care. Legal guardrails on appropriate use cases and information sharing and privacy should also be established before further ramping up the use of AI in healthcare.

Conclusion The rapid emergence of LLMs has introduced a new level of technological capabilities

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into medicine. While innovative, LLMs are neither an infallible process nor an overhyped assistant. They serve as tools and are controlled and understood by the user first.

When applied appropriately, LLMs can speed up and improve documentation, streamline administrative tasks, assist with research, and enhance patient health literacy.

Simultaneously, limitations, “hallucinations,” and liability concerns prevent them from mak ing clear decisions. For spine surgeons, the most productive approach to LLMs is a rational and balanced one. LLMs are best understood as adjunctive tools.

When used appropriately with physician oversight, they can enhance specific aspects of clinical practice without compromising the standards of patient care. l

References 1. KFF Tracking Poll on Health Information and Trust: Use of AI for Health Information and Advice. Kaiser Family Foundation. Published May 6, 2025.

Accessed June 8, 2026. https://www. kff.org/public-opinion/kff-tracking-pollon-health-information-and-trust-use-ofai-for-health-information-and-advice/ 2. Huo B, Boyle A, Marfo N, et al. Large language models for chatbot health advice studies: a systematic review.

JAMA Netw Open. 2025;8(2):e2457879.

3. Kung TH, Cheatham M, Medenilla A, et al. (2023). Performance of ChatGPT on USMLE: Potential for AI-assisted medical education using large language models.

PLOS Digital Health. 2023;2(2):e0000198.

4. Liévin V, Hother CE, Motzfeldt AG, Winther O. Can large language models reason about medical questions? Patterns (New York, N.Y.). 2024;5(3):100943.

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5. Pressman SM, Borna S, Gomez-Cabello CA, Haider SA, Haider CR, Forte AJ. Clinical and surgical applications of large language models: a systematic review. J Clin Med. 2024;13(11):3041.

9. Kocyigit BF, Okyay RA, Seiil B, Qumar AB, Sumbul HE. Analysis of retracted publications on artificial intelligence: trends, ethical concerns, and scientific integrity.

J Korean Med Sci. 2025;40(44):e280.

6. Walters WH, Wilder EI. Fabrication and errors in the bibliographic citations generated by ChatGPT. Sci Rep. 2023;13(1):14045.

10. Ayers JW, Poliak A, Dredze M, et al. Comparing physician and artificial intelligence chatbot responses to patient questions posted to a public social media forum.

JAMA Int Med. 2023;183(6):589–596.

7. Fiorillo L. Confabulated references in the age of AI: contamination of the biomedical scientific literature.

Explor Med. 2026;7:1001385.

8. Resnik DB, Hosseini M. Hallucinated citations produced by generative artificial intelligence may constitute research misconduct when citations function as data in scholarly papers. Accountability Res. Advance online publication. https:// doi.org/10.1080/08989621.2026.2645390

11. Kartal A, Manalil NF, Cheng CD, et al. Evaluating large language models for decision support in minimally invasive spine surgery triage and procedural categories. Global Spine J. Advance online publication. https:// doi.org/10.1177/21925682251411225 12. Demir MT, Kültür Y. A comparative study of orthopedic surgeons and AI models in the clinical evaluation of spinal surgery. J Turkish Spinal Surg. 2025;36(3):125-129.

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From the Department of Orthopaedic Surgery at Rush University Medical Center in Chicago, Illinois, and 2MedStar Health Orthopedics at MedStar Georgetown University Hospital in Washington, D.C. 1

DME in Cervical Spine Surgery What Does the Evidence Say? Mattin Moazzam, BS

1

Aditya Mazmudar, MD, MBA2

Arash Sayari, MD1

Durable medical equipment (DME) for the cer vical spine prescribed postoperatively must be select ive, pat ient-specific, and grounded in clinical e v idenc e. H i stor ic a l l y, t he distribution of postoperative dev ices has been g uided by institutional convention rather than high-level literature. As spine surgery transitions deeper into value-based care models, postoperative modalities must face the same rigorous scrutiny to optimize clinical outcomes while minimizing unnecessary financial and compliance burdens for the patient.

Cervical Collars: Purpose and Types Cervical collars are often prescribed to limit postoperative motion, provide comfort, and offer patients a sense of reassurance during early recovery. It is important to recognize, however, that collars do not replace internal fixation—they supplement it. The degree of immobilization varies substantially by collar type: soft collars, rigid collars, and cervicothoracic orthoses.1–3 Soft collars provide minimal motion restriction, demonstrating poor immobilization in all planes. They function primarily as a comfort measure and proprioceptive reminder to limit neck

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movement.1 Rigid collars such as the Aspen and Miami J provide moderate restriction of flexion and extension but only poor restriction of lateral bending and rotation.

The NecLoc demonstrated t he greatest overall motion restriction among rigid cervical orthoses.1–3 Cervicothoracic orthoses such as the Sternal Occipital Mandibular Immobilizer brace extend fixation to the thorax, providing moderate to substantial restriction of f lexion/extension and rotation, though restriction of lateral bending is comparatively less effective.1,4

Evidence-Based Use of Cervical Collars The routine use of cervical collars after 1- to 2-level anterior cervical discectomy and fusion (ACDF) is not strongly supported by the available evidence. A systematic review of 25 studies found that while cervical collar use improved short-term patient-reported outcomes and early pain control, the majority of the data showed no significant difference in long-term fusion rates between braced and unbraced patients. 5 This finding was corroborated by a comparative cohort study of 83 patients undergoing 1- or 2-level ACDF, which found no statistically significant difference in any clinical measure, fusion rate, subsidence, or complication rate between braced and unbraced groups.6 Despite this lack of clinical evidence, surgeon surveys

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CERVICAL SPINE

revealed that more than 85% of surgeons still prescribe collars after 2-level ACDF, driven primarily by personal experience and colleague recommendations rather than literature evidence, as only 14% cited the literature as the basis for their bracing protocol.7

Bone Growth Stimulators Bone growth stimulators represent a biologic adjunct to spinal fusion. The most commonly prescribed external device for cervical fusion uses pulsed electromagnetic field (PEMF) stimulation, which delivers electromagnetic energy through an external coil worn over the fusion site. The mechanism involves upregulation of growth factors that promote osteoblast activity and bone formation at the fusion interface. 8 Indications for Bone Stimulators Bone growth stimulators are most appropriately considered in patients with identifiable risk factors for pseudarthrosis, including nicotine use, multilevel cervical fusion, revision surgery, and prior pseudarthrosis.

The primary randomized controlled trial specifically evaluating PEMF stimulation in cervical fusion enrolled 323 patients who were either smokers or undergoing multilevel ACDF. At 6 months, the PEMF group demonstrated a significantly higher radiographic fusion rate compared to controls (83.6% vs. 68.6%, p = 0.0065). 9 A broader meta-analysis of 7 randomized controlled trials found t hat electrical stimulation increased the odds of successful fusion by 2.5-fold (OR 2.53, 95% CI 1.86–3.43).10

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“Practically, [bone growth stimulators] cost several thousand dollars, often require insurance preauthorization with documented risk factors, and depend on patient compliance with daily wear over months—a variable that is difficult to monitor or enforce.”

Despite these favorable pooled estimates, bone stimulators have not become universal after cervical fusion. The cervical-specific randomized controlled trial showed that the fusion advantage at 6 months disappeared by 12 months (92.8% vs 86.7%, p = 0.11), suggesting PEMF may accelerate fusion rather than ultimately change the final fusion rate—a critical distinction when baseline fusion rates already exceed 85%. 9 A competing meta-analysis by Matur et al found no significant fusion benefit for PEMF (OR 1.89, 95% CI 0.36–9.80, p = 0.449) and identified a high overall risk of bias in the majority of randomized studies, concluding that the available evidence suggests that routine use of these devices does not significantly improve fusion rates.11 Practically, these devices cost several thousand dollars, often require insurance preauthorization with documented risk factors, and depend on patient compliance w it h daily wear over months—a variable that is difficult to monitor or enforce.11,12

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DME Modalities in Cervical Spine Recovery W h i le or t hoses a nd bone st i mu lators remain t he cornerstones of t radit ional postoperative DME protocols, clinicians are frequently asked to consider secondary adjunctive modalities. These include home-based t her ma l (heat/ice) u n it s, infrared units, transcutaneous electrical nerve stimulation (TENS) units, and low-intensity ultrasound devices. Unlike rigid orthoses or PEMF devices that target macroscopic stability and cellular fusion pathways, secondary modalities focus primarily on peripheral symptom modulation and soft-tissue recovery.

TENS and Infrared Units These modalities target postsurgical myofascial pain and localized spasm. A meta-analysis of 40 randomized controlled trials found that TENS significantly reduced postoperative pain and opioid requirements, and both the American Pain Society and the Orthopaedic Trauma Association recommend it as a postoperative adjunct, though neither recommendation is specific to spine surgery. For infrared/photobiomodulation therapy, a meta-analysis found moderate evidence of clinically meaningful pain reduction in neck pain at optimal wavelengths. However, because standard postoperative cer vical pathways do not universally demonstrate high-level consensus or objective radiographic benefits for these devices, their utilization should be highly individualized and considered as local comfort measures.13–17

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Ultrasound Units While low-intensity pulsed ultrasound is a recognized modality in broader orthopedic fracture care, its routine deployment in cervical spine surgery requires careful distinction from established electrical stimulation therapies like PEMF, which carry the majority of high-level spinal arthrodesis data. In a 2025 systematic review and network meta-analysis of 34 randomized controlled trials involving 2,141 patients w ith neck pain, therapeutic ultrasound demonstrated the lowest relative efficacy among six evaluated biophysical modalities.

Compared with placebo, therapeutic ultrasound showed an estimated mean difference in pain reduction of only −0.59 (95% CI: −1.24 to 0.06) in the network meta-analysis and received the lowest non-placebo P-score (0.1958), indicating inferior comparative performance relat ive to high-intensit y laser therapy, extracorporeal shock wave therapy, interferential current, low-level laser therapy, and TENS. The review noted that therapeutic ultrasound was the only modality that failed to exceed the minimum clinically important difference threshold for neck pain improvement.7 Thermal (Heat/Ice) Units Cryotherapy, delivered through ice packs or continuous cooling dev ices, may reduce postoperative pain and analgesic use through local vasoconstriction, decreased edema, reduced inf lammatory signaling, and slowed nerve conduction. In a broad orthopedic review, significant reductions in pain and opioid consumption were reported

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in approximately half of studies comparing cryotherapy with no cryotherapy (44% of 25 studies evaluating pain and 48% of 23 studies evaluating opioid use), although evidence remains mixed and continuous devices have not clearly proven superior to standard ice packs.18 Local heat therapy may improve pain, stiffness, range of motion, and muscle relaxation through increased tissue temperature and vasodilation.19 However, like soft collars, both function primarily as localized comfort adjuncts rather than long-term drivers of construct success.

Selective Use of Secondary DME Modalities Among secondar y DME modalities, the strength of supporting evidence varies considerably. TENS and photobiomodulation therapy carry the strongest supporting ev-

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idence among secondary modalities, with multiple meta-analyses and society-level recommendations supporting their use as analgesic adjuncts. However, neither modality has demonstrated improvement in f usion or st r uct u ra l outcomes. 14,15, 2 0 Heat therapy is w idely used for muscle relaxation and stiffness during rehabilitation, though high-quality postoperative data rema i n l i m ited. Su rgeons shou ld exercise caution regarding the addition of mu lt iple seconda r y DME dev ices to a postoperative regimen; just as routine bracing after a straightforward ACDF is frequently driven by convention rather than literature, indiscriminate ancillary device prescription risks inf lating healthcare expenditures and increasing patient burden without verifiable improvements in long-term surgical outcomes.

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Conclusions DME after cervical spine surgery should be prescribed with the same evidence-based rigor applied to the surgical procedure itself. Cervical collars remain appropriate in select higher-risk scenarios to limit, but not eliminate, postoperative motion and offer

soft tissue management. Similarly, bone growth stimulators offer a biologic strategy to enhance fusion in patients with identifiable risk factors for pseudarthrosis. A selective, patient-specific approach to DME prescription best serves both clinical outcomes and responsible resource utilization. l

References 1. Holla M, Huisman JMR, Verdonschot N, Goosen J, Hosman AJF, Hannink G. The ability of external immobilizers to restrict movement of the cervical spine: a systematic review. Eur Spine J. 2016;25(7):2023-2036.

2. Askins V, Eismont FJ. Efficacy of five cervical orthoses in restricting cervical motion: a comparison study.

Spine. 1997;22(11):1193-1198.

3. Tescher AN, Rindflesch AB, Youdas JW, et al. Comparison of cervical rangeof-motion restriction and craniofacial tissue-interface pressure with 2 adjustable and 2 standard cervical collars. Spine. 2016;41(6):E304-E312.

4. Holla M, Hannink G, Eggen TGE, Daanen RA, Hosman AJF, Verdonschot N. Restriction of cervical intervertebral movement with different types of external immobilizers: a cadaveric 3D analysis study. Spine. 2017;42(20):E1182-E1189.

5. McKeon JF, Alvarez PM, Castaneda DM, et al. Cervical collar use following cervical spine surgery: a systematic review. JBJS Rev. 2024;12(9).

6. Shin HK, Park D, Jeon SR, Roh SW, Park JH. Is it necessary to use a cervical brace after single- or double-level ACDF? Medicine (Baltimore). 2024;103(27):e38816.

7. Bernucci C, Cracchiolo G, Raspagliesi L, et al. Support or constraint? A comprehensive analysis of postoperative cervical bracing practices: insights from the Italian society of neurosurgery (SINch) survey and a systematic review of the literature.

Eur Spine J. 2025;34(8):3113-3126.

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8. Gan JC, Glazer PA. Electrical stimulation therapies for spinal fusions: current concepts. Eur Spine J. 2006;15(9):1301-1311.

9. Foley KT, Mroz TE, Arnold PM, et al.

Randomized, prospective, and controlled clinical trial of pulsed electromagnetic field stimulation for cervical fusion. Spine J. 2008;8(3):436-442.

10. Akhter S, Qureshi AR, Aleem I, et al.

Efficacy of electrical stimulation for spinal fusion: a systematic review and meta-analysis of randomized controlled Trials. Sci Rep. 2020;10(1):4568.

11. Matur AV, Plummer ZJ, Mejia-Munne JC, et al. Noninvasive electrical stimulation as an adjunct to fusion procedures: a systematic review and meta-analysis. J Neurosurg Spine. 2022;37(1):137-148.

12. Kaiser MG, Eck JC, Groff MW, et al. Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 17: bone growth stimulators as an adjunct for lumbar fusion.

J Neurosurg Spine. 2014;21(1):133-139.

13. Lee JH, Jones JC, Lee DS, Joseph JR. Transcutaneous electrical nerve stimulation for the treatment of acute postoperative pain following spine surgery: a scoping review. J Neurosurg Spine. 2024;41(1):97-104.

14. Qing W, Shi X, Zhang Q, Peng L, He C, Wei Q. Effect of therapeutic ultrasound for neck pain: a systematic review and meta-analysis. Arch Phys Med Rehabil. 2021;102(11):2219-2230.

15. Dorji K, Graham N, Macedo L, et al. The effect of ultrasound or phonophoresis as an adjuvant treatment for non-specific neck pain: systematic review of randomised controlled trials. Disabil Rehabil. 2022;44(13):2968-2974.

16. Hsu JR, Mir H, Wally MK, Seymour RB; Orthopaedic Trauma Association Musculoskeletal Pain Task Force. Clinical practice guidelines for pain management in acute musculoskeletal injury. J Orthop Trauma. 2019;33(5):e158-e182.

17. De Oliveira MF, Johnson DS, Demchak T, Tomazoni SS, Leal-Junior EC. Low-intensity LASER and LED (photobiomodulation therapy) for pain control of the most common musculoskeletal conditions. Eur J Phys Rehabil Med. 2022;58(2):282-289.

18. Kunkle BF, Kothandaraman V, Goodloe JB, et al. Orthopaedic application of cryotherapy: a comprehensive review of the history, basic science, methods, and clinical effectiveness. JBJS Rev. 2021;9(1):e20.00016.

19. Clijsen R, Stoop R, Hohenauer E, et al.

Local heat applications as a treatment of physical and functional parameters in acute and chronic musculoskeletal disorders or pain. Arch Phys Med Rehabil. 2022;103(3):505-522.

20. Cottrill E, Downey M, Pennington Z, et al. Low-intensity pulsed ultrasound as a potential adjuvant therapy to promote spinal fusion: systematic review and meta‐analysis of the available data. J Ultrasound Med. 2021;40(10):2005-2017.

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From the 1Department of Neurosurgery, Corewell Health William Beaumont University Hospital, Oakland University William Beaumont School of Medicine in Royal Oak, Michigan; 2Atlas Spine & Brain in Royal Oak, Michigan; and 3Midwest Orthopedics at RUSH in Chicago, Illinois.

NEW TECHNOLOGY

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Benefits of 3D Anatomical Modeling in Spine Surgery Spi na l su rger y ha s cont i nua l l y evolved alongside advances in medical technology. A field that once was limited to Cartesian coordinates and x-rays has been driven to dynamic 3-dimensional (3D) patient-specific spatial reconstruction.1-3 Although computed tomog raphy (CT) and magnetic resonance imaging (MRI) provide detailed anatomy, complex cases still require mental reconstruction of 3D spaces from 2-dimensional images.

While CT excels at depicting osseous anatomy and bony encroachment, it cannot visualize ligamentous or neural anatomy, and interpretation may be difficult in cases of severe degenerative change or osteopenia.4 MRI provides complementary neural and soft-tissue detail but has lower spatial resolution for bone and is particularly susceptible to metal-related artifacts, complicating accurate corridor assessment, especially in patients who have previous hardware.4 3D anatomical modeling addresses these limitations by transforming patient imaging into manipulable digital or physical representations that better meet operative spatial demands. Recently, 3D modeling has evolved into

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a platform supporting preoperative planning, intraoperative guidance, education, and patient-specific guides and implants.1 This review aims to summarize the clinical, educational, and system-level benefits of 3D anatomical modeling in spine surgery.

Technical Overview and Clinical Applications 3D anatomical modeling transforms clinical imaging, such as MRI and CT, into patient-specific 3D representations through image acquisition, segmentation, reconstruction, post-processing, and visualization or printing.2 Image data are typically exported in DICOM format, after which relevant anatomical structures are segmented using manual, semi-automated, or algorithmic methods.

Segmentation is the most critical step because model fidelity depends on accurate anatomical identification. Manual segmentation offers f lexibilit y but is time-consuming and operator-dependent, whereas algorithmic approaches must be adept to noise to be clinically viable.2 Once segmented, anatomy may be reconstructed using volumetric (direct) rendering, or surface (indirect)

Arush Rao, BS1

Drew Thibault1

Aaryan Patel, BS1

Daniel K. Park, MD3

Christopher J. Elia, MD1,2

Daniel K. Fahim, MD1,2

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NEW TECHNOLOGY

“Surgeons reported that critical anatomical information was better visualized on the biomodel than on conventional imaging in 65% of cases. In 74% of cases, the biomodel altered the planned implantation site of hardware.”

rendering, the latter generating an outer mesh suitable for computer-aided design and manufacturing but sensitive to boundary ambiguity and artifact. 2 In clinical spine workflows, surface mesh reconstruction is most commonly used due to compatibility with printing and implant fabrication.2 These models may be digital, utilizing virtual reality (VR) or augmented reality (AR), or physical, created through 3D printing.

Digital models allow rapid manipulation and measurement, while physical models provide tactile feedback and can serve as intraoperative references or the basis for patient-specific guides and implants.1

Preoperative Planning Benefits The most consistent ly reported benef it of 3D anatomical modeling is improved spatial understanding in complex spinal pathology, including deformity, tumor, congenital anomalies, and revision surgery. In a foundational clinical series of 26 complex spine cases, surgeons reported that critical

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anatomical information was better visualized on the biomodel than on conventional imaging in 65% of cases and exclusively visible on the model in 11%.5 In 74% of cases, the biomodel altered the planned implantation site of hardware, such as adjusting the screw trajectory, vertebral level selection, or fixation points. Surgeons also rated the biomodel as the most useful preoperative visualization modality in 70% of cases and the most useful intraoperative modality in 89%, reflecting enhanced tactile and spatial feedback.5 Biomodel use was also associated with measurable reductions in operative duration, around 22% in deformity cases and 8% in tumor cases, which suggested potential cost offsets. 5 More recent comparative studies indicate that planning benefits are greatest when 3D modeling is paired with concrete workflow changes. In AO Spine type-C thoracolumbar fracture posterior fixation, model-assisted planning with simulated instrumentation and preselection of implants was associated with shorter instrumentation time, reduced blood loss, and reduced fluoroscopy exposure when compared with conventional planning.6 Similar utility has been reported in spinal oncology: Leary et al presented a case series utilizing patient-specific 3D-printed models for complex spinal column tumors. The study demonstrated the model use for both preoperative planning and live intraoperative anatomic reference. Models were used intraoperatively as patient-specific references in most cases and were judged technically useful by surgical teams, particularly for planning osteotomies, conceptualizing

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15 Figure 1. The T3 vertebra model alone.

margins for en bloc resection, and navigating proximity to critical neurovascular and visceral structures, highlighting the role of 3D modeling as a reconstructive planning adjunct.7 Virtual models can provide similar cognitive advantages without printing logistics.

In a randomized study of adolescent idiopathic scoliosis planning using low-cost VR, VR-based planning reduced operative time and blood loss while improving surgeon satisfaction compared with standard 2D CT review.8 Collectively, these findings support interactive 3D models as a key mechanism influencing surgical approach, implant sizing, and trajectory planning.

Impact on Intraoperative Metrics and Surgical Outcomes The strongest quantitative evidence supporting 3D anatomical modeling relates to instrumentation accuracy and perioperative efficiency, particularly for pedicle screw placement. Patient-specific drill guides constrain trajectories based on segmented anatomy, reducing reliance on freehand estimation. A large systematic review and meta-analysis demonstrated that 3D-printed drill guides significantly improved the odds of accurate pedicle screw placement compared with freehand techniques, with additional reductions in operative time and intraoperative blood loss in subgroup analyses. 9,10 Figures 1 through 3 are examples of such guides.

3D modeling also has been shown to benefit modern navigation and robotic systems by serving as the geometric foundation for

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Figure 2. The drill guide attached to the T3 vertebra

Figure 3. The drill guide and T3 vertebra separated to show how they fit together.

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Figure 4. Augmedics augmented reality headset.

trajectory planning and operative image alignment. Evidence suggests that their benefits may be the most in anatomically complex cases, where freehand methods may begin to struggle. Furthermore, these systems may reduce radiation exposure by limiting f luoroscopy with continuous intraoperative guidance.11 Clinical reports describe surgeons using reconstructed 3D vertebral models to inform robotic surgical strategy development and intraoperative approaches.12 Augmented reality (Figure 4) further extends 3D modeling into the operative field by overlaying patient-specific anatomy and planned trajectories in real time. Early clinical series report high pedicle screw placement accuracy using AR-assisted workflows, particularly in complex anatomy, although

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broader effectiveness and cost data remain limited.13 Beyond guidance systems, intraoperative 3D imaging can influence surgical outcomes.

Large cohort studies show intraoperative imaging enables immediate corrective actions, such as screw repositioning or additional decompression, that may prevent later complications or need for reoperations.14

Educational and Patient-Centered Benefits 3D anatomical modeling also has tremendous educational value for trainees by enabling low-risk rehearsal of technically demanding tasks. Low-cost printed spine models allow for practice of surgical techniques, including placement of pedicle screws, with models providing tactile feedback approximating

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cortical and cancellous bone. Reports describe high perceived utility among residents using printed models for screw training.15 Patient-centered benefits include improved understanding of spinal patholog y and planned surgical interventions. Systematic reviews across neurosurgical education literature report that physical biomodels and mixed-reality representations enhance patient comprehension compared with traditional imaging explanations, reducing preoperative anxiety.16 In spine surgery, where informed consent requires appreciation of neurologic risk, these communication benefits may meaningfully support shared decision-making.

Cost, Value, and Health System Considerations Costs associated with 3D anatomical modeling are largely front-loaded and include segmentation labor, model preparation, printing, and occasionally sterilization.17 These constraints may severely limit practicality in emergent cases. Current literature suggests that modeling may offset its cost through reductions in operating room time, fluoroscopy exposure, or complication-related downstream costs. However, reported cost savings are highly variable across institutions, and robust cost-effectiveness trials have not been conducted.17 Adoption may be more effective through selective use in complex cases that may preferentially benefit from these 3D models.

Latest Advances Recent advancements focus on automation,

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personalization, and real-time integration.

AI-driven segmentation tools trained on large, diverse clinical datasets now enable rapid segmentation with a high degree of accuracy, addressing the scalability bottleneck in clinical workflows.18 Beyond segmentation, emerging research demonstrates feasibility of automated pedicle screw trajectory planning using AI-based shape completion and 3D reconstruction, achieving accuracy comparable to CT-based planning in experimental settings.19 AR–based intraoperative workf lows are reframing 3D models as real-time guidance tools rather than preoperative references, with early clinical series reporting high pedicle screw placement accuracy in anatomically distorted cases.13 Moreover, advances in additive manufacturing are accelerating development of patient-specific implants, including personalized interbody devices with favorable early outcomes attributed to tailored endplate geometry and load distribution.17 Together, these developments signal a shift toward an integrated and adaptive surgical ecosystem.

Limitations Despite increasing adoption, several limitations persist. Model generation remains time and labor intensive largely owing to segmentation requirements, inaccuracies, or oversimplification of image-to-model conversion, which can misrepresent anatomy.20 Utility is also best utilized in elective settings, as emergent cases often lack sufficient lead time necessary to accurately generate models. Additionally, while improvements

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in instrumentation accuracy and perioperative metrics are well supported, evidence for consistent long-term benefits and definitive cost-effectiveness remains limited.

Conclusion 3D anatomical modeling has evolved into a personalized platform supporting preoperative planning, intraoperative guidance, education, and patient-specif ic instrumentation in spine surgery.1 The strongest

evidence supports improvements in pedicle screw accuracy and perioperative efficiency when modeling is integrated into active workflows.6,9 Educational and patient-communication benefits are also consistently reported. W hile cost-effectiveness and long-term outcomes remain incompletely defined, 3D modeling is best viewed as an adjunct to conventional imaging, with the clearest value in complex cases requiring enhanced spatial understanding. l

References 1. O’Brien S, Darwish N. 3D visualisation of the spine. Adv Exp Med Biol. 2023;1406:139-168.

2. Fletcher J. Methods and applications of 3D patient-specific virtual reconstructions in surgery. Adv Exp Med Biol. 2022;1356:53-71.

3. Mao JZ, Agyei JO, Khan A, et al. Technologic evolution of navigation and robotics in spine surgery: a historical perspective.

World Neurosurg. 2021;145:159-167.

4. American College of Surgeons Committee on Trauma. Best Practices Guidelines: Spine Injury. Chicago, IL: American College of Surgeons; March 2022.

5. Izatt MT, Thorpe PL, Thompson RG, et al. The use of physical biomodelling in complex spinal surgery. Eur Spine J. 2007;16(9):1507-1518.

6. Öztürk AM, Süer O, Govsa F, Özer MA, Akçalı Ö. Patient-specific three-dimensional printing spine model for surgical planning in AO spine type-C fracture posterior long-segment fixation. Acta Orthop Traumatol Turc. 2022;56(2):138-146.

7. Leary OP, Crozier J, Liu DD, et al.

Three-dimensional printed anatomic modeling for surgical planning and real-time operative guidance in complex primary spinal column tumors: single-center experience and case series.

World Neurosurg. 2021;145:e116-e126.

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8. De Salvatore S, Vadalà G, Oggiano L, Russo F, Ambrosio L, Costici PF. Virtual reality in preoperative planning of adolescent idiopathic scoliosis surgery using Google cardboard. Neurospine. 2021;18(1):199-205.

14. Sembrano JN, Santos ER, Polly DW Jr. New generation intraoperative three-dimensional imaging (O-arm) in 100 spine surgeries: does it change the surgical procedure?

J Clin Neurosci. 2014;21(2):225-231.

9. Yu C, Ou Y, Xie C, Zhang Y, Wei J, Mu X. Pedicle screw placement in spinal neurosurgery using a 3D-printed drill guide template: a systematic review and meta-analysis. J Orthop Surg Res. 2020;15(1):1.

15. Patchana T, Ramnot A, Farr S, et al.

Thoracic pedicle screw placement utilizing hands-on training session on three-dimensional models. Cureus. 2022;14(8):e28544.

10. Wei F, Li Z, Liu Z, et al. Upper cervical spine reconstruction using customized 3D-printed vertebral body in 9 patients with primary tumors involving C2. Ann Transl Med. 2020;8(6):332.

11. Ohashi H, Kawamura D, Hatano K, et al. Intraoperative cone-beam computed tomography assessment of spinal pedicle screws placement precision is in full agreement with postoperative computed tomography assessment.

World Neurosurg. 2023;175:e254-e263.

12. Chen HY, Xiao XY, Chen CW, et al.

A spine robotic-assisted navigation system for pedicle screw placement. J Vis Exp. 2020;(159):10.3791/60924.

13. Nadeem-Tariq A, Kazemeini S, Kaur P, et al. Augmented reality in spine surgery: a narrative review of clinical accuracy, workflow efficiency, and barriers to adoption. Cureus. 2025;17(6):e86803.

16. Bauer S, Haegler J, Cipriani D, et al.

Effectiveness of 3D printed and mixed reality models in neurosurgical patient education: a systematic review. Brain Hemorrhages. Published online August 30, 2025. doi:10.1016/j.hest.2025.08.002 17. Parr WCH, Burnard JL, Wilson PJ, Mobbs RJ. 3D printed anatomical (bio) models in spine surgery: clinical benefits and value to health care providers.

J Spine Surg. 2019;5(4):549-560.

18. Wasserthal J, Breit HC, Meyer MT, et al.

TotalSegmentator: robust segmentation of 104 anatomic structures in CT images.

Radiol Artif Intell. 2023;5(5):e230024.

19. Massalimova A, Bauer D, Cavalcanti N, Carrillo F, Mazda F, Fuernstahl P. Feasibility of automatic screw planning via transformer-based shape completion from RGB-D imaging. Sci Rep. 2025;15(1):37617.

20. Ekman T, Barakat A, Heiberg E. Generalizable deep learning framework for 3D medical image segmentation using limited training data. 3D Print Med. 2025;11(1):9.

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

SPINAL DEFORMITIES

What Are the Modifiable and Protective Strategies to Mitigate Proximal Junctional Kyphosis and Failure in Adult Spinal Deformity Surgery Adult spinal deformit y (ASD) surger y is known to offer substantial improvements in pain, function, and qualit y of life for appropriately selected patients.1 However, long-segment thoracolumbar fusion remains one of t he most mechanica lly demanding procedures in spine surgery. 2 Complications at the top of the construct continue to challenge surgeons. 2 Proximal junctional k yphosis (PJK) and proximal junct iona l failure (PJF) are among t he complications that represent a clinically important spectrum of postoperative junctional complications. 3 PJK is typically described as a radiographic increase in k y phosis immediately above t he upper instrumented vertebra (UIV) that forms because of a stress riser created by the fusion construct.4 PJF represents the more severe end of the spectrum of PJK, typically involving fracture, neurologic deficit, pain, or need for revision surgery.4 The clinical burden of proximal junctional complications is substantial, as PJK has been reported in approximately 10% to 40%

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Joshua M. Samaniego, MS

Aditya Mazmudar, MD, MBA of ASD patients. 5 Many cases of PJK are radiographic and asymptomatic, but PJF is more consequential, often requiring revision surgery and contributing to morbidity, cost, and patient dissatisfaction.4 Since PJF is a major driver of reoperNathan Lee, MD ation after complex deformity correction, prevention must be treated as a central goal of preoperative surgical planning and operative execution.6 This article emphasizes a shift from simply identifying risk factors toward modif y ing risk and applying protective strategies during the index operation. (Table 1)

Preoperative Modifiable Strategies Bone Health Optimization Bone quality is one of the most important modifiable variables in adult spinal deformity surgery.7 Conditions such as osteopenia and osteoporosis increase the risk of complications like vertebral compression fracture and junctional collapse at t he

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Table 1. Preventive Strategies for Proximal Junctional Failure or Kyphosis by Operative Phase

Strategy Category

Specific Interventions Preoperative Phase

Patient optimization

Bone health optimization (DEXA screening, initiate anabolic therapy such as teriparatide or romosozumab), vitamin D and calcium repletion

Risk stratification

Identify high-risk patients (elderly, osteoporosis, high BMI, prior surgery, sagittal imbalance)

Alignment planning

Age-adjusted alignment goals; avoid overcorrection of sagittal parameters (PI–LL mismatch, SVA)

Surgical planning

Appropriate selection of UIV (avoid junctional zones, consider extending to more stable levels such as upper thoracic spine when indicated)

Frailty optimization

Nutritional support, prehabilitation, management of comorbidities

Construct Design

Use transition rods (eg, 6.0 to 5.5 mm), avoid overly rigid constructs, consider hybrid constructs

Proximal junction protection

Use of hooks at UIV, ligamentous augmentation (tethers), preservation of posterior ligamentous complex

Soft tissue preservation

Minimize disruption of paraspinal musculature and posterior tension band at UIV

Alignment execution

Avoid overcorrection; ensure smooth transition of sagittal alignment across construct

Cement augmentation

Vertebral augmentation (UIV/UIV+1) in osteoporotic patients

Implant strategy

Avoid aggressive pedicle screw placement at UIV; consider hooks or less rigid fixation proximally

Intraoperative Phase

Postoperative Phase Bracing

Short-term postoperative bracing in high-risk patients

Activity modification

Gradual return to activity; avoid early excessive flexion or loading

Bone health maintenance

Continue osteoporosis therapy (especially anabolic agents transitioning to antiresorptives)

Surveillance

Routine radiographic follow-up for early detection of proximal junctional changes

Rehabilitation

Structured physical therapy focusing on posture, core strength, and spinal mechanics

Abbreviations: BMI, body mass index; DEXA, dual-energy x-ray absorptiometry; SVA, sagittal vertical axis; PI-LL, pelvic incidence-lower lumbar; UIV, upper instrumented vertebra.

UIV or 1 level cranial to the UIV (UIV+1). 8 In patients undergoing long constructs to the pelvis, the transition from a rigid instrumented spine to a mobile osteoporotic segment creates a high-stress environment.9 If the vertebra above the construct cannot tolerate this stress imbalance, PJK may progress to structural PJF.4

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Preoperative bone healt h assessment should therefore be routine for older adult pat ients w it h spina l deformit y and for younger patients with risk factors such as metabolic bone disease or chronic steroid use.10 Dual-energ y x-ray absorptiometr y (DE X A) rema i ns t he sta nda rd screening tool. 10 St ill, preoperat ive CT-based

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Hounsfield unit measurements have increasingly been used as a proxy for bone quality, especially when CT imaging is often routinely obtained for surgical planning.10 Hounsfield units below 146, a threshold for osteoporosis (sensitivit y and specificit y of 94.3% and 87.5%, respectively) at the planned UIV or UIV+1 may help surgeons prepare a more protective fixation strategy to reduce junctional fractures.

Osteoporosis and osteopenia treatment should be indiv idualized but generally includes v itamin D and calcium repletion, as well as pharmacologic therapy if indicated.11 In addition, coordination with multidisciplinar y care, such as primar y care and endocrinolog y, can help w it h treatment. Antiresorptive agents such as bisphosphonates a nd denosu mab may be appropriate in selected patients, but anabolic therapy has gained particular interest in deformity surgery because the goal is not merely to slow bone loss but to improve bone formation and fixation strength.11 Reviews of PJK and PJF prevention consistently emphasize osteoporosis optimization as a core preventive strategy.11 The protective principle is straightforward: improving bone quality at and above the UIV reduces the risk that the junctional vertebra will fail under the new mechanical demands created by deformity correction and fusion.11

Frailty, Sarcopenia, and Nutrition PJK and PJF are not purely radiographic or implant-related problems but are also manifestations of patient biology. 3 Frailty,

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“The protective principle is straightforward: improving bone quality at and above the UIV reduces the risk that the junctional vertebra will fail under the new mechanical demands created by deformity correction and fusion.” sarcopenia, and nutrition deficiencies can impair recovery and reduce the patient’s ability to compensate for the biomechanical stress of a long fusion. 3 Sarcopenia may be particularly relevant because paraspinal musculature contributes to the dynamic stabilization of the thoracolumbar spine. 3 When muscle mass and quality are poor, the proximal junction may be more vulnerable to collapse, progressive kyphosis, and failure. 3 Nutritional status should be assessed before surgery, especially in revision and high-risk patients.12 Checking albumin, prealbumin, and vitamin D levels alongside asking about weight loss and dietary intake history may help identify patients who would benefit from nutritional intervention.12,13 Dietitian involvement can be useful before and after surgery, particularly when sarcopenia or protein-calorie malnutrition is suspected.13 Frailty and sarcopenia may also inf luence construct planning.14 In patients with poor bone quality and paraspinal atrophy, surgeons may favor constructs that end in

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Figure 1. Pre- and postoperative images of an adult with spinal deformity and proximal junctional kyphosis.

more stable regions rather than stopping at vulnerable transition zones.14 Some cases may require extension to the upper thoracic spine to avoid ending in a structurally compromised segment.14 Prehabilitation may also be considered for frail or deconditioned patients.15 Although the evidence base is still developing, preoperative physical therapy and nutritional assessments are logical interventions for optimizing functional and physiological reserve in high-risk patients before a high-risk operation.15

Preoperative Planning and UIV Selection Level selection is one of the most important surgical decisions in preventing proximal ju nct iona l complicat ions. 3 End ing t he construct at the apex of a kyphotic curve,

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within a junctional zone, or at a structurally weak vertebra can concentrate stress at the proximal endpoint.16 The UIV should be selected with attention to regional alignment, planned correction magnitude, and the patient’s global deformity pattern.16 Several practical principles are commonly applied. The construct should generally avoid ending at the apex of thoracic kyphosis.17 If bone quality in the lower thoracic spine is poor according to DEX A or CT Hounsfield units, extension to the upper thoracic spine may be safer.17 If there is substantial paraspinal muscle atrophy, a more proximal UIV may also be considered to distribute stress across a more stable region.18 Newer planning concepts, including the use of the posterior cranial vertical line and upper thoracic alignment targets,

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may further refine UIV selection among the levels of T2, T3, and T4.18 Equally important is alignment planning.

Overcorrection is a well-recognized contributor to PJK and PJF, especially in older patients whose physiologic alignment may not match “ideal” young-adult spinopelvic parameters.19 Contemporary work has increasingly emphasized age-adjusted alignment and global proportionality rather than rigid correction to universal targets.19 The T4-L1-hip axis concept, including T4 pelvic angle, L1 pelvic angle, and the hip-axis error between thoracic and lumbar correction, reflects this movement toward more personalized alignment planning.19 A 2025 study specifically evaluated T4-L1 hip-axis error and L1 pelvic-angle error as predictors of mechanical failure after long fusion for adult spinal deformity. Earlier work on the T4-L1-hip axis proposed sagittal realignment targets for long-construct deformity correction. 20 The practical takeaway is that preventing overcorrection is itself a PJK-prevention strategy. Correction should restore functional alignment without forcing a frail patient into a sagittal profile they cannot tolerate biomechanically. 20 An example of this principle is shown in Figure 1. A 74-year-old pat ient w it h multiple risk factors developed acute PJF within 2 weeks of long-segment deformity correction, likely related to overcorrection.

Revision surgery incorporated undercorrection according to T4PA and L1PA mismatch parameters and proximal tether augmentation, resulting in subsequent radiographic improvement.

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Intraoperative Protective Strategies Soft-Tissue Preservation at the UIV Structures such as the posterior ligamentous complex, facet capsules, interspinous ligaments, supraspinous ligament, and paraspinal musculature provide important stabilit y at the prox imal junction. 21 Excessive dissection, disruption of t he facet capsule above the UIV, or violation of the posterior tension band can destabilize the adjacent mobile segment. 21 Therefore, meticulous soft-tissue preservation at the UIV and UIV+1 is one of the most intuitive and widely recommended protective strategies. 21 The goal is to create a gradual transition bet ween t he f used and unf used spine.

Avoiding unnecessary stripping of the posterior elements, preserving the proximal facet joints, and minimizing damage to the interspinous and supraspinous ligaments may reduce abrupt stress concentration. 22 Techniques such as muscle-sparing exposure and approaches designed to preserve stabilizing soft tissues have been proposed to mitigate junctional failure risk. 22 The hybrid open muscle-sparing approach is an example of a focus on preserving the posterior soft-tissue envelope at the proximal junction. This concept emphasizes the importance of maintaining the integrity of the posterior ligamentous complex, paraspinal musculature, and fascial attachments at the UIV and adjacent levels. 22 Excessive disruption of these stabilizing structures during exposure and instrumentation may weaken the transition zone between the rigid fusion construct and the mobile spine.

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Construct Design and Rod Considerations Construct stiffness is central to PJK biomechanics. 23 Long fusion constructs create a rigid lever arm. 23 At the UIV, that rigidity abruptly transitions to the mobile native spine.23 The stiffer the construct, the greater the potential stress concentration at this transition. 23 Rod material and diameter may therefore matter. Cobalt-chromium rods offer high stiffness and fatigue strength, which may be advantageous for maintaining correction and preventing rod fracture. 24 However, excessive rigidity may theoretically increase junctional stress. 24 Titanium rods have a lower modulus of elasticity, which may provide a more forgiving construct. 24 However, t hey may be less resistant to fatigue in high-load environments. 24 The optimal material likely depends on several factors, such as the patient’s presentation and treatment goals. 24 Transitional rods represent one strategy to reduce abrupt stiffness mismatch. 25 These rods taper from a larger diameter distally, such as 6.0 mm, to a smaller diameter proximally, such as 5.5 mm, creating a more gradual transition at the UIV.25 The rationale is similar to that of a “soft landing”: reduce the sudden change in rigidity between the instrumented and noninstrumented spine.25 Hybrid constructs, hooks, tethers, and transition rods all share this conceptual goal. 25 Proximal Fixation and Augmentation The choice of proximal fixation may influence PJK risk. 26 Pedicle screws provide

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strong 3-column fixation but may create a rigid endpoint. 26 Transverse process hooks or other less rigid fixation methods at the UIV may distribute forces more gradually and reduce stress risers. 26 Some surgeons may prefer hooks at the UIV for this reason, particularly in the upper thoracic spine. 23 Cement augmentation of the UIV and/ or UIV+1 pedicle screw fixation is another preventive strateg y for patients w ith poor bone quality. 23 Fenestrated pedicle screws w it h cement aug mentat ion can improve screw purchase. 2 3 Meanwhile, vertebroplast y at the UIV or UIV+1 may reduce the risk of compression fracture. 23 However, aug mentat ion must be used selectively because cement can also alter local stiffness and has its own risks. 23 The current literature suggests that prophylactic strategies such as tethering, hooks, and vertebral augmentation may reduce PJK or PJF risk in selected patients, but the optimal combination remains dependent on the patient’s circumstances. 23,27

Junctional Tethers and Ligament Augmentation Junctional tethering has become one of the most discussed protective strategies for PJK prevention. 28 Tethers are designed to recreate or supplement the posterior tension band above the UIV. 28 Techniques var y, which include Mersilene tape, polyethylene tape, sublaminar bands, spinous-process fixation, and tethering from the UIV to UIV+1 or UIV+2. 28 The goal is to dampen flexion forces and provide a controlled transition between the fused and unfused segments.28

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The literature generally supports t he biomechanical rationale for tethering, but clinical outcomes vary by several factors, such as technique, tensioning, patient selection, and construct characteristics.28 Tethers may be most useful in high-risk patients. 28 They should not be viewed as a substitute for appropriate alignment planning or bone health optimization. 28 Rather, they are one component of a broader prevention bundle.28

Postoperative Strategies For postoperative prevention, bone health management should continue in patients with osteopenia or osteoporosis, with particular consideration of anabolic therapy when appropriate. 29 For patients started on teriparatide or another anabolic agent preoperatively, continuation after surgery may help support fusion biology and reduce junctional fracture risk. 29 After an anabolic course, transition to an antiresorptive agent may be considered to maintain gains in bone density. 29 Nutrition should also remain a priority, as a dietitian consultation should be considered for specific patients who could benefit from it to promote an uneventful postoperative recover y with adequate wound healing. 29 The role of postoperative bracing remains debated. Bracing may provide short-term comfort and external support, especially in high-risk patients, but evidence that it definitively prevents PJK or PJF is limited as some studies suggest that bracing does not reduce PJK incidence. 30-32 Similarly, postoperat ive physica l t herapy shou ld be individualized. 33 Early rehabilitation

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should avoid certain actions, such as excessive f lexion, heav y lifting, and abrupt loading, while emphasizing safe mobility and gradual return to activity. 33 For frail or deconditioned patients, supervised therapy may help restore function while minimizing unsafe movement patterns. 33 Radiographic surveillance is essential as early detection of warning signs, such as progressive junctional kyphosis, UIV/UIV+1 fracture, implant loosening, or worsening sagittal imbalance, allows closer monitoring and timely intervention. 3 Not every radiographic PJK case requires revision surgery, but worsening patient symptoms or structural failure should prompt careful evaluation. 3

Conclusion PJK and PJF are multifactorial complications, for which no single intervention reliably eliminates risk. Instead, prevention requires a multimodal, patient-specific strateg y that begins before surger y and continues through postoperative care. Many factors, such as bone health optimization, frailty and nutrition management, thoughtful UIV selection, avoidance of overcorrection, preservation of proximal soft tissues, careful construct design, selective use of hooks, tethers, or cement augmentation, and ongoing postoperative surveillance, all contribute to risk reduction. For ASD patients, the best opportunity to prevent PJF is at the index operation, when modifiable risk factors can be addressed and protective strategies can be intentionally built into the surgical plan. l

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References 1. Riley MS, Bridwell KH, Lenke LG, Dalton J, Kelly MP. Health-related quality of life outcomes in complex adult spinal deformity surgery. J Neurosurg. 2017;28(2):194-200.

2. Chatelain L, Dib A, Ponchelet L, Ferrero E. Proximal junctional kyphosis above long spinal fusions. Orthop Trauma Surg Res. 2024;111(1):104065.

3. Lee BJ, Bae SS, Choi HY, et al. Proximal junctional kyphosis or failure after adult spinal deformity surgery - review of risk factors and its prevention. Neurospine. 2023;20(3):863-875.

4. Hyun SJ, Lee BH, Park JH, Kim KJ, Jahng TA, Kim HJ. Proximal junctional kyphosis and proximal junctional failure following adult spinal deformity surgery. Neurospine. 2017;14(4):126-132.

5. Hostin RA, Yeramaneni S, Gum JL, Smith JS. Clinical and economic impact of proximal junctional kyphosis on pediatric and adult spinal deformity patients.

Int J Spine Surg. 2023;17(S2):S9-S17.

6. Park JS, Kim HJ, Park SJ, Kang DH, Lee CS. A comprehensive review of risk factors and prevention strategies: how to minimize mechanical complications in corrective surgery for adult spinal deformity. Asian Spine J. 2025;19(3):463-475.

7. Arora A, Cummins DD, Wague A, et al.

Preoperative medical assessment for adult spinal deformity surgery: a state-of-the-art review. Spine Deformity. 2023;11:773-785.

8. Filley A, Baldwin A, Ben-Natan AR. The influence of osteoporosis on mechanical complications in lumbar fusion surgery: a systematic review. NASS J. 2024;18:100327.

9. Viswanathan VK, Ganguly R, Minnema AJ, et al. Biomechanical assessment of proximal junctional semi-rigid fixation in long-segment thoracolumbar constructs.

J Neurosurg. 2018;30(2):184-192.

10. Kim KJ, Kim DH, Lee JI, Choi BK, Han IH, Nam KH. Hounsfield units on lumbar computed tomography for predicting regional bone mineral density.

Open Med. 2019;14(1):545-551.

11. Al-Najjar YA, Quraishi DA, Kumar N, Hussain I. Bone health optimization in adult spinal deformity patients: a narrative review. J Clin Med. 2024;13(16):4891.

12 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(S1):S26-S32.

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13. Wang SK, Li J, Wang P, et al. Comparison of four nutritional screening tools for predicting postoperative adverse events following degenerative spinal deformity surgery. Spine. 2024;49(8):536-546.

techniques to prevent proximal junctional kyphosis and proximal junctional failure in adult spinal deformity correction—a systematic review of biomechanical studies. Spine J. 2021;21(5):842-854.

14. Pinter ZW, Bernatz J, Mikula AL, et al. Paraspinal sarcopenia and lower Hounsfield units are independent predictors of increased risk for proximal junctional complications following thoracolumbar fusions terminating in the upper thoracic spine. Global Spine J. 2025;15(4):1914-1923.

24. Shega FD, Zhang H, Manini DR, Tang M, Liu S. Comparison of effectiveness between cobalt chromium rods versus titanium rods for treatment of patients with spinal deformity: a systematic review and meta-analysis. Adv Orthop. 2020;8475910.

15. Kim DU, Park HK, Lee GH, et al. Central sarcopenia, frailty and comorbidity as predictor of surgical outcome in elderly patients with degenerative spine disease. J Korea Neurosurg Soc. 2021;64(6):995-1003.

16. Ye J, Gupta S, Farooqi AS, et al. Predictive role of global spinopelvic alignment and upper instrumented vertebra level in symptomatic proximal junctional kyphosis in adult spinal deformity. J Neurosurg. 2023;39(6):774-784.

17. Virk S, Platz U, Bess S, et al. Factors influencing upper-most instrumented vertebrae selection in adult spinal deformity patients: qualitative case-based survey of deformity surgeons. J Spine Surg. 2021;7(1).

18. Katsuura Y, Lafage R, Kim HJ, et al.

Alignment targets, curve proportion and mechanical loading: preliminary analysis of an ideal shape toward reducing proximal junctional kyphosis.

Global Spine J. 2021;12(6):1165-1174.

19. Joseph K, Bui TT, Yahanda AT, et al.

Mechanical failures as predicted by achieving local versus global T4-L1 hip axis goals: a single-center experience. Spine. 2026;51(10):708-716.

20. Hills J, Mundis G, Klineberg EO, et al. The T4-L1-hip axis: sagittal spinal realignment targets in long-construct adult spinal deformity surgery: early impact.

J Bone Joint Surg. 2024;106(23):e48.

21. Korkmaz M, Akgul T, Sarıyılmaz K, et al. Effectiveness of posterior structures in the development of proximal junctional kyphosis following posterior instrumentation: A biomechanical study in a sheep spine model. Acta Orthop Traumatol Turc. 2019;53(5):385-389.

22. Park PJ, Lombardi JM, Lenke LG. The hybrid open muscle-sparing approach in adult spinal deformity patients undergoing lower thoracic fusion to the pelvis.

Neurospine. 2021;18(1):234-239.

23. Doodkorte RJP, Vercoulen TFG, Roth AK, de Bie RA, Willems PC. Instrumentation

25. Bess S, Harris JE, Turner AWL, et al. The effect of posterior polyester tethers on the biomechanics of proximal junctional kyphosis: a finite element analysis.

J Neurosurg. 2016;26(1):125-133.

26. Solomon E, Bronheim RS, Hassanzadeh H. Prevention of proximal junctional kyphosis using proximal fixation techniques.

Int J Spine Surg. 2023;17(S2):S47-S57.

27. Li D, Sun X, Li J, et al. Does vertebral cement augmentation reduce postoperative proximal junction complications in spinal deformity corrective surgery: a systematic review and meta-analysis. Neurospine. 2025;22(1):51-66.

28. Sursal T, Kim HJ, Sardi JP, Yen CP, Smith JS. Use of tethers for proximal junctional kyphosis prophylaxis in adult spinal deformity surgery: a review of current clinical evidence. Int J Spine Surg. 2023;17(S2):S26-S37.

29. Bryant JP, Perez-Roman RJ, Burks SS, Wang MY. Antiresorptive and anabolic medications used in the perioperative period of patients with osteoporosis undergoing spine surgery: their impact on the biology of fusion and systematic review of the literature. J Neurosurg. 2021;50(6):E13.

30. Crawford S, Lara N, Revella J, et al.

Postoperative bracing does not improve the rate of proximal junctional kyphosis in adult spinal deformity [Abstract P86]. Spine J. 2020;20(9):S188.

31. Lord EL, Ayres E, Woo D, et al. The impact of global alignment and proportion score and bracing on proximal junctional kyphosis in adult spinal deformity.

Global Spine J. 2021;13(3):651-658.

32. Shahi P, Merrill RK, Pajak A, et al. Post-operative hyperextension bracing has the potential to reduce proximal junctional kyphosis: a propensity matched analysis of braced versus non-braced cohorts.

Global Spine J. 2025;15(3):1695-1702.

33. Sakaguchi T, Gunjotikar S, Tanaka M, et al. Evaluation and rehabilitation after adult lumbar spine surgery.

J Clin Med. 2024;13(10):2915.

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

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Annular Repair After Microdiscectomy Does It Prevent Reherniation?

Symptomatic reherniation occurs in 7% to 18% of patients following lumbar discectomy. Annular defect size at the time of surgery is one of the most significant pred ictors of t hat r isk. 1 Ca r ragee et a l prospectively classified 187 consecutive patients undergoing single-level primary discectomy by annular competence and fragment morphology. The fragment-defect group—extruded fragments with wide posterior annular loss—had a 27% reherniation rate and 21% reoperation rate at minimum 2-year follow-up, compared to 1% each in the fragment-fissure group with intact annular rims. 2 A subsequent meta-analysis of 7 comparative studies across 1,653 patients found that residual annular defects of 6 mm or greater carried a pooled odds ratio of 2.5 (p = 0.004) for symptom recurrence and 2.3 (p < 0.001) for reoperation relative to smaller defects, with approximately 30% to 44% of discectomy patients having a defect exceeding that threshold.1 The avascular architecture of the annulus fibrosus limits its reparative response, with healing typically producing disorganized fibrous tissue rather than restoration of nat ive lamellar collagen. The decision between limited and subtotal nucleus removal involves a trade-off. Disc height loss is more significant in subtotal discectomy

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Brandon P. Hirsch, MD

but may reduce reherniation rates while conservative nucleus removal preserves disc height but carries a higher residual reherniation burden. 3

Prior Techniques and Available Devices Several approaches to annular repair have been attempted over the past 2 decades, none with durable clinical success. Suture repair, fibrin glue, and polyethylene plug constructs each failed to achieve meaningful adoption, partly due to concern that these approaches cannot withstand the intradiscal pressures of normal activity. The Xclose (Anulex Technologies, Minnetonka, MN) enrolled 750 patients in a randomized trial and showed numerically lower reherniation rates at every time point but failed to achieve statistical significance in the overall population. Anulex Technologies ceased operations in 2014 and the device is no longer available.

The AnchorKnot (Anchor Orthopedics XT, Mississauga, ON) carries the CE (Conformité Européenne) mark and US Food and Drug Administration (FDA) clearance for soft tissue approximation broadly and is listed as commercially available, but it has been used off-label for annular repair. No published human clinical outcome data exist for this indication.

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PATIENT OUTCOMES

Figure 1. The Barricaid device (Intrinsic Therapeutics, Woburn, MA).

The bone-anchored annular closure device (Barricaid, Intrinsic Therapeutics, Woburn, MA; distributed by Orthofix) is currently the only device with FDA Premarket Approval—the Class III pathway—supported by published human clinical outcome data for annular repair after discectomy (Figure 1). Rather than approx imating annular edges, it deploys a f lexible polyethylene terephthalate polymer mesh to physically occlude the defect, secured to the adjacent vertebral endplate via a titanium anchor.

Fixation derives from bone rather than from the annular rim itself.

Clinical Evidence and Limitations A multicenter RCT enrolled 554 patients at 21 European centers between 2010 and

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2014, randomizing pat ients w it h int raoperative annular defects of 6 to 10 mm in width and minimum disc height of 5 mm following limited microdiscectomy to the Barricaid device or control, w ith no additional nucleus removal in either arm. Thomé et al reported the 2-year results in in 2018, meeting both prespecified endpoints: symptomatic reherniation (12% vs 25%, p < 0.001) and overall success on a composite clinical outcome measure (Table 1).4 Kienzler et al published 3-year follow-up findings in 2019, demonstrating sustained separation between groups on reherniation and reoperation rates, with patient-reported leg pain, back pain, Oswestry Disability Index (ODI), and 36-item Short Form (SF-36) Physical Component Summary scores all favoring the device. 5 Thomé et al. subsequent ly published a 5-year secondary analysis in 2021, reporting continued separation at 18.8% vs 31.6% symptomatic reherniation (p < 0.001). 6 Pat ient-repor ted outcomes—VA S leg and back pain, ODI, and SF-36 physical component scores—all favored the device arm at 3 years. 5 A second RCT by Cho et al (n = 60, 24-month follow-up) reported reherniation rates of 3.3% vs 20.0%.7 Li et al published a 2023 systematic review of 5 RCTs across 2,380 patients that found the device reduced reherniation from 17.6% to 7.4% and reoperation from 13.6% to 5.4%. 8 Several limitations of this evidence base warrant consideration. All major Barricaid trials were industr y-funded by Intrinsic Therapeutics, and multiple investigators ac ross st ud ies d i sclosed con su lt a nc y

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Table 1. Reherniation and Reoperation Rates Across Follow-up Time Points.

Time Point

Symptomatic Reherniation, ACD vs Control

Reoperation, ACD vs Control

2-year data (Thomé et al, 2018)

12% vs 25% (p < 0.001)

5% vs 13% (p = 0.001)

3-year data (Kienzler et al, 2019)

14.8% vs 29.5% (p < 0.001)

11.0% vs 19.3% (p = 0.007)

5-year data (Thomé et al, 2021)

18.8% vs 31.6% (p < 0.001)

16.0% vs 22.6% (p = 0.03)

ACD = anterior cervical discectomy.

relationships with the sponsor. Patients and investigators were unblinded after ra ndom i z at ion, i nt roduci ng potent ia l per for ma nce bias in reoperat ion decisions. No follow-up data beyond 5 years are currently available. The incremental implant cost and approximately 18-minute increase in operative time are practical considerations not addressed in the primary efficacy literature.

Additionally, vertebral endplate change s — er o s i v e b on y c h a n ge s at t he a nchor-endplate interface on postoperative computed tomography—were present in 84% of device patients vs 30% of controls at 2 yea rs. 4 However, no reoperat ions were performed specifically for endplate changes, and patients with these findings outperformed those without on reherniat ion a nd pat ient-repor ted outcomes, suggesting the imaging finding may not carry adverse clinical significance in the available follow-up period. Whether this remains true beyond 5 years is unknown.

Device migration occurred in 3 of 276 patients, and one device-related nerve root injury was reported in the trial.

Patient Selection and Coding The evidence supports a narrow indication:

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primary limited discectomy for symptomatic lumbar disc herniation with radiculopathy, intraoperative defect of 6 mm or greater, and preserved disc height of at least 5 mm.

Defect size must be measured intraoperatively. The evidence does not extend to severe disc degeneration with collapsed disc height, prior surgery at the index level, or osteoporosis where anchor purchase may be inadequate. Among patients managed with discectomy alone in the trial, females younger than 50 years with large defects had up to approximately 10 times the reherniation risk of other demographic groups. 9 The International Society for the Advancement of Spine Surgery published its initial policy statement supporting the device in 2019 and issued an updated statement in June 2025 incorporating 5-year data and revised coding guidance.10 Current Procedural Terminology add-on code 63032 took effect January 1, 2026—a Category I designation that replaces the facility Healthcare Common Procedure Coding System code C9757 that had been in use since 2020.

International Classification of Diseases, 10th Revision, codes for annular defect size, introduced in 2022, allow documentation of the intraoperative finding driving medical necessity.

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Summary Annular defect size is a modifiable intraoperative risk factor for reherniation that has been studied for decades w ithout a durable clinical solution. Prior tissue-approximation approaches, including the only device that reached a large randomized trial, failed to demonstrate statistically significant benefit and are no longer commercially available. The bone-anchored device represents a design shift—mechanical occlusion rather than tissue repair—and has produced reductions in symptomatic reher n iat ion a nd reoperat ion across 5 years of follow-up in multiple controlled

studies. Several limitations apply: all major trials were industry-funded with disclosed investigator conf licts, follow-up beyond 5 years is absent, and the unblinded design introduces potential bias in reoperation decisions. The indication is narrow and requires intraoperative defect measurement, adding time and implant cost to a procedure surgeons have performed efficiently for decades. W het her t he absolute risk reduction observed in the trial population justifies those trade-offs in a given patient is a judgment that the available data can inform but not resolve. l

References 1. Miller LE, McGirt MJ, Garfin SR, Bono CM. Association of annular defect width after lumbar discectomy with risk of symptom recurrence and reoperation: systematic review and meta-analysis of comparative studies. Spine. 2018;43(5):E308–E315.

5. Kienzler JC, Klassen PD, Miller LE, et al; Annular Closure RCT Study Group.

Three-year results from a randomized trial of lumbar discectomy with annulus fibrosus occlusion in patients at high risk for reherniation. Acta Neurochirurgica. 2019;161(7):1389–1396.

8. Li W-S, Li G-Y, Yan Q, Chen W-T, Cong L. The effectiveness and safety of annulus closure device implantation in lumbar discectomy for patients with lumbar disc herniation: a systematic review and meta-analysis.

Eur Spine J. 2023;32(7):2377–2386.

2. Carragee EJ, Han MY, Suen PW, Kim D. Clinical outcomes after lumbar discectomy for sciatica: the effects of fragment type and anular competence.

J Bone Joint Surg. 2003;85(1):102–108.

6. Thomé C, Kuršumović A, Klassen PD, et al; on behalf of the Annular Closure RCT Study Group. (2021).

Effectiveness of an annular closure device to prevent recurrent lumbar disc herniation: A secondary analysis with 5 years of follow-up. JAMA Netw Open. 2021;4(12):e2136809.

9. Martens F, Vajkoczy P, Jadik S, Hegewald A, Stieber J, Hes R; on behalf of the Anular Closure RCT Study Group.

Patients at the highest risk for reherniation following lumbar discectomy in a multicenter randomized controlled trial.

JBJS Open Access. 2018;3(2):e0037.

3. McGirt MJ, Eustacchio S, Varga P, et al. A prospective cohort study of close interval computed tomography and magnetic resonance imaging after primary lumbar discectomy: factors associated with recurrent disc herniation and disc height loss.

Spine. 2009;34(19):2044–2051.

4. Thomé C, Klassen PD, Bouma GJ, et al; on behalf of the Annular Closure RCT Study Group. Annular closure in lumbar microdiscectomy for prevention of reherniation: a randomized clinical trial. Spine J. 2018;18(12):2278–2287.

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7. Cho PG, Shin DA, Park SH, Ji GY. Efficacy of a novel annular closure device after lumbar discectomy in Korean patients: a 24-month follow-up of a randomized controlled trial. J Korean Neurosurg Soc. 2019;62(6):691–699.

10. Lorio M. ISASS recommendations and coverage criteria for bone-anchored annular defect closure following lumbar discectomy: an ISASS 2025 policy update. Int J Spine Surg. 2025;19(4):444.

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From the 1Department of Orthopaedics at the Hospital for Special Surgery in New York City, New York, and 2Weill Cornell Medical College in New York City, New York.

OUTCOME MEASURES

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Minimal Clinically Important Difference in Spine Surgery Are We Using the Right Thresholds?

Sereen Halayqeh, MD1

P a t i e n t-r e p or t e d ou t c om e m e a s u r e s (PROMs) now sit near the center of spine outcomes research because the question that matters after surger y is not simply whether radiographs improved, whether a fusion healed, or whether a p value crossed 0.05. The more important question is whether the patient’s pain, function, and quality of life changed in a way that matters to the person living with the result. That is the gap minimal clinically important difference (MCID) was designed to address.

Jaeschke et al originally framed the MCID as the smallest change in health status that patients themselves would identify as important.1 In spine surgery, that concept is useful because statistically significant improvement can still be clinically trivial, while a patient-centered improvement may be obscured if investigators focus only on mean score changes.

This framework fits naturally into spine surger y because the field relies heavily on PROMs such as disability scales, pain scores, and general health-status instrument s. T he s e mea su re s help c apt u re what imaging and technical endpoints often cannot: whether patients can walk farther, sit longer, sleep better, return to work, or function w ith less pain. MCID

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gives those numerical changes a clinical reference point by asking whether the amount of improvement was meaningful, not merely measurable.

However, MCID is not a uniMichael Greenberg, BA1 versal constant, and its interpretation depends on both the clinical and methodological contex t. T h is tension mot ivates the central question of this review: are current MCID thresholds appropriate for all Sravisht Iyer, MD1,2 spine surgery patients, or are they often treated with more certainty than the evidence justifies?

What Is MCID? MCID refers to the smallest change in an outcome score that patients perceive as important enough to matter in real life or to justify a change in management. 2 In spine surgery, it is usually applied to PROMs such as the Oswestr y Disabilit y Index (ODI), Neck Disability Index (NDI), visual analog or numeric pain scales, SRS-22, EQ-5D, and Patient-Reported Outcomes Measurement Information System (PROMIS) measures. 2–4 These tools measure related but distinct domains, including disability, pain inten-

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sity, physical function, quality of life, and overall health status. 5 The definition sounds simple, but the number itself is not built into the questionnaire. It is an estimate produced by a method, of which there are multiple. Anchor-based methods link score change to an external reference, such as a patient’s globa l rat ing of improvement. 1–3 These approaches come closest to the intuitive idea of “meaningful to the patient,” but they depend on the wording, timing, and reliability of the anchor. Distribution-based methods use statistical properties of the score, such as standard deviation, standard error of measurement, or effect size. These methods are useful for judging whether change exceeds measurement noise, but they do not by themselves prove that the change matters to patients.

This distinction matters because different methods answer different questions. 2 As a resu lt, 2 st udies can eva luate t he same PROM and arrive at different MCID thresholds without either being obviously w rong. 6 The difference may ref lect t he pat ient popu lat ion, basel i ne sever it y, follow-up interval, statistical method, or clinical context.

For that reason, MCID is best understood as a context-dependent decision threshold rather than a permanent property of ODI, NDI, VAS, or any other scale. It is also only a minimal threshold. A patient who reaches MCID has likely improved in a meaningful way, but that does not necessarily mean the patient is satisfied, symptom-free, or functioning well relative

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to desired outcomes. Related concepts such as substantial clinical benefit and patient acceptable sy mptom state may prov ide additional context and are discussed later in this review.

How MCID Is Used in Spine Surgery In spine surgery, treatment often focuses on outcomes that cannot easily be captured by standard follow-up tools like imaging or blood work, such as patient pain, mobility, and quality of life. MCID functions as a translation device between questionnaire change and clinical interpretation.

A postoperative mean improvement may be statistically significant, but clinicians, researchers, payers, and patients usually want a more practical answer: how many patients improved enough for the change to matter? MCID helps answer that question by shifting the focus from outcome detectability to outcome relevance.

This is why MCID is commonly used in studies of lumbar, cervical, and deformity surgery. A lumbar surgery study may report the proportion of patients who achieved MCID on ODI or back-pain scores. A cerv ical surger y study may use NDI, neck pain, or arm pain. Deformity studies may rely on SRS-22 domains, and newer work increasingly includes PROMIS measures.7,8 Across these settings, MCID gives authors a way to describe surgical benefit in patient-centered terms rather than relying only on average score changes.

At the same time, routine use of MCID can create a false sense of precision when thresholds are quoted without attention to

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how they were calculated, in whom they were derived, and at what follow-up time point. The issue is not that one threshold is necessarily wrong. The problem is that quoting a single MCID w it hout its surrounding context can make the threshold seem more portable than it really is.

Broader literature on interpreting change scores illustrates the value of considering ranges and clinical context rather than relying only on rigid point estimates.7 That same logic should apply to spine-specific PROMs. A threshold used to compare average improvement across a cohort may not be appropriate for deciding whether one individual patient had a successful recovery.

Moder n hea lt h s ystems i ncreasi ng ly emphasize outcomes that matter to patients, which makes MCID attractive for registries, comparative-effectiveness research, and quality dashboards. However, those uses require transparency. If MCID thresholds are applied without attention to method, population, baseline severity, and follow-up time, they risk turning a patient-centered concept into a simplified reporting metric. Used carefully, MCID can make spine surger y outcomes more interpretable. Used rigidly, it can oversimplify a recovery process that is inherently variable across patients.

Why Current MCID Thresholds May Not Be Perfect Although MCID is widely used in spine surgery outcomes research, current thresholds should be interpreted with caution.

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“If MCID thresholds are applied without attention to method, population, baseline severity, and follow-up time, they risk turning a patient-centered concept into a simplified reporting metric.”

One of the main limitations is that MCID values can vary depending on the method used to calculate t hem. A nchor-based, distribution-based, and receiver operating characteristic methods may produce different thresholds even when applied to the same patient population and the same outcome measure. In lumbar spine surgery, Copay et al demonstrated that different calculation methods generated different MCID estimates for the ODI, SF-36, and pain scales, highlighting that MCID is not a single fixed value but a method-dependent estimate. 3 More recent met hodological work has similarly emphasized that MCID thresholds in spine surgery depend on the selected calculation method, anchor, and clinical context. 9 A not her impor ta nt lim itat ion is t hat d i f ferent PROMs have d i f ferent MCID thresholds. Measures such as ODI, NDI, visual analog scale pain scores, PROMIS Physical Function, and PROMIS Pain Interference evaluate related but distinct aspects of recovery. Therefore, a clinically meaningful improvement in pain may not

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always correspond to a clinically meaningful improvement in disability or quality of life. Hung et al showed that MCID estimates varied widely across PROMIS, NDI, and ODI instruments among patients with spinal conditions, reinforcing t hat t hresholds cannot be applied interchangeably across outcome measures.10 The same MCID threshold may also not work equally well for every patient. Baseline pain and disabilit y are particularly important. A patient with severe preoperative disability has more room to improve than a patient with mild symptoms, while a patient with mild baseline disability may have limited ability to achieve a large absolute score change despite being satisfied with the outcome. Asher et al found that a 30% reduction from baseline in disability and pain performed similarly or better than fixed absolute MCID values after lumbar spine surgery, especially among patients at the extremes of baseline severity.11 This f inding suggests t hat baseline severit y should be considered when interpreting whether a patient achieved meaningful improvement.

Diagnosis and procedure type can further inf luence MCID interpretation. Patients undergoing surgery for lumbar disc herniation, spinal stenosis, degenerative spondylolist hesis, cer v ical radiculopathy, cervical myelopathy, or adult spinal deformity may have different symptoms, expectations, recovery patterns, and surgical goals. Power et al evaluated lumbar spine surger y pat ients across different degenerative diagnoses and concluded that

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pathology-specific MCID thresholds may be needed rather than applying a single threshold across all lumbar conditions.12 Similarly, the clinical meaning of improvement after a limited decompression may differ from improvement after a multilevel fusion or deformity correction, where recovery time, surgical burden, and patient expectations are substantially different.

Follow-up timing is another important consideration. Some patients may achieve MCID early after surgery, while others improve gradually over months or years. In a lumbar surgery cohort, Asher et al showed that 3-month ODI outcomes did not fully capture 12-month improvement, indicating that early assessment may underestimate meaningful recovery in some patients.13 In degenerative cervical myelopathy, additional patients continued to achieve MCID at later follow-up time points af ter t he early postoperative period.14 Therefore, the timing of PROM collection may inf luence whether a patient is classified as having achieved meaningful improvement.

Finally, achieving MCID does not necessarily mean that the patient is satisfied or has reached an acceptable final health state. MCID measures change from baseline, but it does not fully account for the patient’s final symptom burden, expectations, or goals. For example, a patient may improve enough to meet MCID but still have substantial residual pain or disability. Shahi et al showed that MCID and patient acceptable symptom state (PASS) do not always identify the same patients af ter lumbar spine surger y, indicat ing

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that meaningful improvement and acceptable final status are related but distinct concepts.15 Patient expectations are also closely linked to satisfaction after spine surger y, and fulfillment of expectations may inf luence how patients perceive their su rg ica l outcome beyond PROM score changes alone.16

Should We Use More Flexible Thresholds?

Given these limitations, fixed MCID values may be too simplistic for the broad range of patients and procedures in spine su rger y. However, t h is does not mea n that MCID should be abandoned. Rather, MCID should be interpreted more f lexibly and in the appropriate clinical context. A single absolute threshold may be useful for reporting group-level outcomes, but it may not fully ref lect individual patient recovery, especially across heterogeneous spine populations.

Percentage improvement is one potential approach to make MCID interpretation more individualized. Unlike fixed pointchange thresholds, percentage improvement accounts for the patient’s baseline score. In lumbar spine surgery, Asher et al found that a 30% reduction from baseline in pain and disability was a valid and practical method for defining clinically meaningful improvement and performed as well as or better than absolute pointchange thresholds.11 Similar findings have been reported in cervical spine surgery, w here a 30% reduc t ion f rom basel i ne was also supported as a valid approach

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for defining meaningful improvement in disability and pain.17 Other outcome thresholds may also provide useful clinical context. PASS ref lects whether the patient has reached a symptom state that they consider acceptable, while substantial clinical benefit (SCB) ref lects a larger magnitude of improvement than MCID. These concepts answer different questions. MCID asks, “Did the patient improve by a meaningful amount?”

PASS asks, “Is the patient’s current state acceptable?” SCB asks, “Did the patient achieve a substantial benefit?” Glassman et al emphasized that MCID may represent a f loor for improvement rather than the ideal treatment goal and proposed SCB thresholds after lumbar spine arthrodesis.18 More recent work has also supported the use of PASS as a complementary measure because it capt u res t he pat ient’s f i na l postoperative state rather than only the degree of change from baseline.19 Therefore, future spine outcomes reporting may benefit from using MCID alongside percentage improvement, PASS, SCB, and patient-specific goals. This approach may provide a more complete assessment of recovery than MCID alone. In clinical practice, 2 patients may achieve the same PROM score change but interpret t heir outcomes differently depending on their baseline symptoms, expectations, work demands, neurologic status, and desired level of activ it y. For this reason, MCID should be considered one part of a broader patient-centered assessment rather than a stand-alone definition of surgical success.

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Conclusion MCID remains a valuable tool in spine su rger y outcomes resea rch because it helps translate changes in PROMs into clinically meaningful information. However, MCID should not be used as a onesize-fits-all measure. Relying on a single f i xed t h reshold may oversi mpl i f y t he

complexity of recovery after spine surgery.

Moving forward, MCID should be interpreted alongside percentage improvement, PASS, SCB, and individual patient goals.

Ultimately, MCID should guide outcome interpretation, but it should not replace cl i n ica l judg ment or pat ient-centered assessment. l

References 1. Jaeschke R, Singer J, Guyatt GH. Measurement of health status. Control Clin Trials. 1989;10(4):407–415.

2. Copay AG, Subach BR, Glassman SD, Polly DW, Schuler TC. Understanding the minimum clinically important difference: a review of concepts and methods. Spine J. 2007;7(5):541–546.

3. Copay AG, Glassman SD, Subach BR, Berven S, Schuler TC, Carreon LY. Minimum clinically important difference in lumbar spine surgery patients: a choice of methods using the Oswestry Disability Index, Medical Outcomes Study questionnaire Short Form 36, and pain scales. Spine J. 2008;8(6):968–974.

4. Carreon LY, Glassman SD, Campbell MJ, Anderson PA. Neck Disability Index, Short Form-36 physical component summary, and pain scales for neck and arm pain: the minimum clinically important difference and substantial clinical benefit after cervical spine fusion. Spine J. 2010;10(6):469–474.

5. NIH Common Fund. Patient-Reported Outcomes Measurement Information System (PROMIS). https:// commonfund.nih.gov/promis.

6. Tubach F, Wells GA, Ravaud P, Dougados M. Minimal clinically important difference, low disease activity state, and patient acceptable symptom state: methodological issues. J Rheumatol. 2005;32(10):2025–2029.

7. Ostelo RWJG, Deyo RA, Stratford P, et al. Interpreting change scores for pain and functional status in low back pain. Spine (Phila Pa 1976). 2008;33(1):90–94.

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8. Issa TZ, Lee Y, Henry TW, et al. Values derived from patient-reported outcomes in spine surgery: a systematic review of the minimal clinically important difference, substantial clinical benefit, and patient acceptable symptom state.

Eur Spine J. 2023;32(10):3333–3351.

14. Evaniew N, Coyle M, Rampersaud YR, et al. Timing of recovery after surgery for patients with degenerative cervical myelopathy: an observational study from the Canadian Spine Outcomes and Research Network.

Neurosurgery. 2023;92(2):271–282.

9. Klukowska AM, Vandertop WP, Schröder ML, Staartjes VE. Calculation of the minimum clinically important difference using different methodologies: case study and practical guide. Eur Spine J. 2024;33(9):3388–3400.

15. Shahi P, Subramanian T, Maayan O, et al. Preoperative disability influences effectiveness of MCID and PASS in predicting patient improvement following lumbar spine surgery. Clin Spine Surg. 2023;36(10)–E511.

10. Hung M, Saltzman CL, Kendall R, et al.

What are the MCIDs for PROMIS, NDI, and ODI instruments among patients with spinal conditions? Clin Orthop Relat Res. 2018;476(10):2027–2036.

16. Rampersaud YR, Canizares M, Perruccio AV, et al. Fulfillment of patient expectations after spine surgery is critical to patient satisfaction: a cohort study of spine surgery patients.

Neurosurgery. 2022;91(1):173–181.

11. Asher AM, Oleisky ER, Pennings JS, et al. Measuring clinically relevant improvement after lumbar spine surgery: is it time for something new? Spine J. 2020;20(6):847–856.

12. Power JD, Perruccio AV, Canizares M, et al. Determining minimal clinically important difference estimates following surgery for degenerative conditions of the lumbar spine: analysis of the Canadian Spine Outcomes and Research Network registry.

Spine J. 2023;23(9):1323–1333.

13. Asher AL, Chotai S, Devin CJ, et al.

Inadequacy of 3-month Oswestry Disability Index outcome for assessing individual longer-term patient experience after lumbar spine surgery. J Neurosurg Spine. 2016;25(2):170–180.

17. Khan I, Pennings JS, Devin CJ, et al.

Clinically meaningful improvement following cervical spine surgery: 30% reduction versus absolute pointchange MCID values. Spine (Phila Pa 1976). 2021;46(11):717–725.

18. Glassman SD, Copay AG, Berven SH, Polly DW, Subach BR, Carreon LY. Defining substantial clinical benefit following lumbar spine arthrodesis. J Bone Joint Surg Am. 2008;90(9):1839–1847.

19. Goh GS, Soh RCC, Yue WM, Guo CM, Tan SB, Chen JLT. The patient acceptable symptom state for the Oswestry Disability Index following single-level lumbar fusion for degenerative spondylolisthesis.

Spine J. 2021;21(4):598–609.

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From the 1Department of Orthopaedics at the Hospital for Special Surgery in New York City, New York, and 2Weill Cornell Medical College in New York City, New York.

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The Role of Preoperative Bone Optimization in Spine Surgery Osteoporosis and low bone mineral density (BMD) are among the most consequential and most frequently overlooked risk factors in elective spine surgery. Based on published literature, approximately one-third to one-half of patients presenting for instrumented spine procedures meet criteria for osteoporosis or osteopenia, and the majority are unaware of the diagnosis at the time of surgical consultation.1,2 Compromised bone quality drives the mechanical complications that most often necessitate a return to the operating room: cage subsidence, pedicle screw loosening and pullout, pseudarthrosis, adjacent-level fracture, and proximal junctional kyphosis or failure (PJK/PJF) in long constructs.2,3 As the surgical population ages and indications broaden, the costs associated with treating these complications—affecting both patients and healthcare systems—are significant and largely preventable. Therefore, preoperative bone health optimization (BHO) is increasingly being accepted as a standard of care rather than just an optional measure.4

How to Identify Patients at Risk Impaired bone quality is common in elective spine patients, with most having osteoporosis or osteopenia detected through preoperative screening. Guidance from societies—including the American Academy of Orthopaedic Surgeons, the North American Spine Society,

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Atahan Durbas, MD and the American Orthopaedic Association’s “Own the Bone” program—recommends screening all women aged ≥65 years, men aged ≥70 years, postmenopausal women younger t han 65 years and men aged 50–70 Sheeraz A. Qureshi, MD, MBA2 years with risk factors, and any adult with a fragility fracture, prolonged glucocorticoid use, >1.5 inches height loss, hyperparathyroidism, chronic kidney disease, malabsorption, or heav y smoking/alcohol use. 2,5 However, in the clinic, many patients were identified using simple criteria like history of fragility fracture, height loss, glucocorticoid use, or FRAX score.1,6 In adult spinal deformity, low BMD is independently associated with higher rates of mechanical failure and revision.7 A recent meta-analysis in degenerative cervical surgery similarly linked osteoporosis to reduced fusion rates and increased complications.8 In short, patients with poor bone quality have worse outcomes, and most can be identified before reaching the operating room.

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Assessment Tools Dual-energy X-ray absorptiometry (DEXA), opportunistic computed tomography (CT), and magnetic resonance imaging (MRI) vertebral bone quality (VBQ) score can all be

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Figure 1. Three common bone health evaluation methods: (a) DEXA for bone mineral density and T-scores; (b) CT-based HU measurement from L1 vertebral body; and (c) MRI-based VBQ score from L1–L4 vertebral bodies and L3 cerebrospinal fluid region. These methods show standard densitometric, CT-based, and MRI-based approaches to assessing bone quality.

used to assess a patient’s bone health prior to surgery. Figure 1 provides an example image from each of these 3 tools.

DEXA remains the World Health Organization’s reference standard, but degenerative changes, osteophytes, and aortic calcifications routinely inflate lumbar T-scores in the very patients that spine surgeons see. Hip and distal radius sites are useful complements when the lumbar reading is suspect.9 Even if the spine reading is acceptable, one should use the worst region to predict complications.

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Opportunistic CT Hounsfield units (HU), measured at L1 or a target vertebra, are now well established, do not require additional imaging, and bypass the confounding factors of DEXA. Threshold values differ by series, but measurements ≤110–120 HU are associated with osteoporosis and can forecast mechanical issues.10,11 The MRI vertebral bone quality (VBQ) score—calculated as the ratio of the trabecular signal from L1–L4 to cerebrospinal fluid signal on T1-weighted images—offers a

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radiation-free option when MRI is available.

A VBQ score of ≥3.0–3.5 indicates a higher risk for mechanical complications.12,13 HU and VBQ are complementary, and either can be used opportunistically to prompt a formal workup.13

Pharmacologic Optimization and Timing Clinics should always start with a basic laboratory evaluation that includes 25-hydroxyvitamin D, serum calcium, and renal function, with secondary workup as indicated.6 For patients diagnosed with osteoporosis, it is advisable to consider pharmacologic treatment prior to elective instrumented surgery.

Pharmacotherapy is the most actionable component of BHO. The agents fall into two classes: anabolic and antiresorptive.

Anabolic (bone-building) agents include teriparatide and abaloparatide (parathyroid hormone analogs) and romosozumab (anti-sclerostin antibody) actively build trabecular and cortical bone, act quickly, and are the preferred preoperative choice for patients undergoing instrumented surgery. Teriparatide has the most extensive track record in spine fusion: randomized and observational data demonstrate higher fusion rates, faster time to fusion, and lower rates of pedicle screw loosening compared with bisphosphonates.14,15 Romosozumab is newer but achieves comparable or greater BMD gains in a shorter treatment window.

Emerging spine-specific data show reductions in mechanical complications, especially screw loosening, PJK/PJF, and reoperation after corrective deformity surgery.15,16

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Antiresorptive agents, including bisphosphonates and denosumab, slow bone loss rather than build new bone. Evidence of their effect on fusion is more mixed, and they are most often used as maintenance therapy after an anabolic course or as first-line therapy when anabolic options are contraindicated, declined, or unaffordable.14,15 Vitamin D repletion (target 25-OH-D >30 ng/mL) and adequate dietary calcium are foundational and should be addressed in every patient. Low preoperative vitamin D levels have been independently associated with lower fusion rates and instrumentation failure.6 Most published protocols recommend a minimum of 2–3 months of preoperative therapy, with several authors and recent consensus statements favoring 3–6 months when feasible, continued for at least 8–12 months postoperatively depending on the construct.6 For carefully chosen high-risk patients, especially those with long deformity constructs in osteoporotic women, a short delay in surgery to finish an anabolic treatment can be a sensible trade-off against the significant risk of needing a revision.

Challenges and Building a Workflow The primary obstacle to BHO is operational rather than clinical. Spine surgeons alone cannot manage osteoporosis effectively, and informal referrals often result in patients being lost to follow-up. Successful programs typically include a specific screening trigger within the new-patient process; a direct referral route to a bone health clinic, fracture liaison service, or endocrinologist capable

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of prescribing and monitoring treatment; a clear hand-back to the surgeon once the patient is medically ready; and standardized follow-up evaluations such as repeat DEXA or HU scans to assess response. Recent experiences at single centers show that dedicated bone health clinics significantly increase treatment initiation and may reduce hardware failures and revisions in patients undergoing spinal fusion.17

Conclusion Preoperative bone optimization is a highly

underutilized strategy to reduce mechanical complications in spine surgery, particularly during spinal instrumentation. Patients at risk can be easily identified, assessments are becoming simpler (which is most often based on imaging already collected), and medications are effective. The workflow for BHO is also reproducible. As the patient demographic and technical complexity of our procedures age, BHO should be regarded with the same importance as smoking cessation, glycemic management, and nutritional improvement in preoperative care. l

References 1. Anderson PA, Kadri A, Hare KJ, Binkley N. Preoperative bone health assessment and optimization in spine surgery.

Neurosurg Focus. 2020;49(2):E2.

2. Anderson PA, Binkley NC, Bernatz JT. Bone health optimization (BHO) in spine surgery. Spine (Phila Pa 1976). 2023;48(11):782-790.

3. Al-Najjar YA, Quraishi DA, Kumar N, Hussain I. Bone health optimization in adult spinal deformity patients: a narrative review. J Clin Med. 2024;13(16):4891.

4. Pasqualini I, Huffman N, Keller SF, et al. Team approach: bone health optimization in orthopaedic surgery.

JBJS Rev. 2023;11(12):e23.00178.

5. Anderson PA, Jeray KJ, Lane JM, Binkley NC. Bone health optimization: beyond own the bone: AOA critical issues. J Bone Joint Surg Am. 2019;101(15):1413-1419.

6. 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 (Phila Pa 1976). 2022;47(2):128-135.

7. Katiyar P, Reyes J, Coury J, Lombardi J, Sardar Z. Preoperative optimization for adult spinal deformity surgery: a systematic review. Spine (Phila

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Pa 1976). 2024;49(5):304-312.

8. Lechtholz-Zey EA, Ayad M, Gettleman BS, et al. Systematic review and meta-analysis of the effect of osteoporosis on fusion rates and complications following surgery for degenerative cervical spine pathology.

Int J Spine Surg. 2024;18(3):277-286.

9. Sangondimath G, Sen RK, T FR. DEXA and imaging in osteoporosis. Indian J Orthop. 2023;57(suppl 1):82-93.

10. Schreiber JJ, Anderson PA, Rosas HG, Buchholz AL, Au AG. Hounsfield units for assessing bone mineral density and strength: a tool for osteoporosis management. J Bone Joint Surg Am. 2011;93(11):1057-1063.

11. Nakarai H, Kazarian GS, Lovecchio FC, Kim HJ. Hounsfield units and vertebral bone quality score for predicting mechanical complications after adult spinal deformity surgery: a systematic review and meta-analysis.

Asian Spine J. 2024;18(5):719-730.

12. 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.

13. Kinoshita Y, Taniwaki H, Namikawa T, et al. Predicting osteoporosis-related complications in lumbar spine surgery using

Hounsfield unit and vertebral bone quality scores: a 5-year follow-up study with principal component analysis insights.

Eur Spine J. 2025;34(11):5148-5156.

14. Ohtori S, Inoue G, Orita S, et al. Comparison of teriparatide and bisphosphonate treatment to reduce pedicle screw loosening after lumbar spinal fusion surgery in postmenopausal women with osteoporosis from a bone quality perspective. Spine (Phila Pa 1976). 2013;38(8):E487-492.

15. Mikula AL, Lakomkin N, Hamouda AM, et al. Change in spinal bone mineral density as estimated by Hounsfield units following osteoporosis treatment with romosozumab, teriparatide, denosumab, and alendronate: an analysis of 318 patients. J Neurosurg Spine. 2024;41(3):309-315.

16. Sawada Y, Takahashi S, Yasuda H, et al. Effect of romosozumab administration on proximal junctional kyphosis in corrective spinal fusion surgery.

Spine J. 2025;25(6):1218-1228.

17. Suarez-Nieto MV, Malacon K, Fox A, et al. Bone optimization for perioperative spine patients: a multidisciplinary approach at a single academic center.

J Clin Med. 2025;14(24):8866.

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From the Department of Orthopaedic Surgery at the University of California, Irvine, School of Medicine in Costa Mesa, California.

EVIDENCE SUMMARY

What Is the Ideal Mattress Type for Patients With Chronic Neck and Low Back Pain?

Sleep and rest are very important for health and healing. A good night’s sleep restores a person’s energy so they can fully participate in their personal and professional lives.

However, studies show that 15% to 30% of people report sleep disorders.1 Neck and low back pain are common causes of poor sleep quality. A quality mattress is important for sleep and resting, and mattress stiffness is not one-size-fits all. The majority of hospital mattresses are firm to medium-firm, which may not be optimal for all patients (Figure 1). Because back pain is one of the most common chief complaints in the United States, patients often ask spine surgeons the best mattress type to use after surgery or what mattresses alleviate low back pain.

Currently, there is no evidence-based consensus on the ideal mattress for patients with neck or low back pain.

One important factor when evaluating mattresses is firmness. In their double-blinded, multicenter, randomized controlled trial, Kovacs et al evaluated mattress firmness in 315 patients with isolated chronic low back pain. 2 They found that patients who used medium-firm mattresses had better pain in bed, pain on rising, and disability outcomes after 90 days than the firm mattress cohort. 2 Patients with medium-firm

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Yu-Po Lee, MD

mattresses also had less daytime low-back pain than patients with firm mattresses.

This finding is important because patients with chronic low back pain often use their beds to rest or recover when they have low back pain flare-ups. Caggiari et al performed a meta-analysis of all articles evaluating the best mattress types.1 A total of 39 qualified articles were included in the study. The authors concluded that a medium-f irm

Figure 1. Hospital bed with a medium-firm mattress

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EVIDENCE SUMMARY

mattress promotes the best sleep and alignment. So, while more studies need to be conducted before a definitive conclusion can be drawn, the evidences suggests that a medium-firm mattress may be better for patients who have chronic neck and low back pain.

Mattress type and quality also plays a role in sleep quality. Radwan et al performed a meta-analysis of the best type and characteristics of a mattress for decreasing spinal pain and improving sleep quality. 3 Twenty-four articles were included in their study.

They found that patients using medium-firm mattresses with self-adjusted custom inf lation had less pain. Heated mattresses also resulted in less pain. Hence, patients whose neck and back pain did not improve with a medium-firm mattress alone may benefit from a custom inf lated mattress and a heating pad.

Pillow t y pe can also impact neck and back pain. Chun-Yiu et al conducted a meta-analysis on 35 studies regarding pillow type and neck pain and sleep quality.4 The authors found that pillow designs did not

inf luence sleep qualit y in patients with chronic neck pain. However, the authors did conclude that the cervical alignment may be significantly impacted by the shape and height of the pillow. Therefore, avoiding pillows that excessively flexed or extended the neck may help patients with chronic neck and low back pain.

Conclusion Experts continue to debate the single best mattress type for patients with chronic neck and low back pain. However, the evidence suggests that a medium-firm mattress may help decrease back pain. Custom-inflated mattresses and heat may also provide benefit. Other factors such as an adjustable bed may help patients get in and out of bed.

There is less literature on ideal pillow type, but pillow height, which can keep the neck in a neutral position, may help decrease neck pain. More studies are needed for definitive consensus, but surgeons can still make evidence-based mattress and pillow recommendations to their patients with chronic back and neck pain. l.

References 1. Caggiari G, Talesa GR, Toro G, Jannelli E, Monteleone G, Puddu L. What type of mattress should be chosen to avoid back pain and improve sleep quality? Review of the literature. J Orthop Traumatol. 2021;22(1):51.

2. Kovacs FM, Abraira V, Peña A, et al. Effect of firmness of mattress on chronic non-specific low-back

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pain: randomised, double-blind, controlled, multicentre trial. Lancet. 2003;362(9396):1599-604.

3. Radwan A, Fess P, James D, et al.

Effect of different mattress designs on promoting sleep quality, pain reduction, and spinal alignment in adults with or without back pain; systematic review of controlled trials.

Sleep Health. 2015;1(4):257-267.

4. Chun-Yiu JP, Man-Ha ST, Chak-Lun AF. The effects of pillow designs on neck pain, waking symptoms, neck disability, sleep quality and spinal alignment in adults: A systematic review and meta-analysis. Clin Biomech (Bristol). 2021;85:105353.

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From the 1Department of Orthopaedic Surgery at the University of California Davis Health in Sacramento, California, and 2Hospital for Special Surgery and Weill Cornell Medical College in New York City, New York.

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Second Victim Syndrome and Spine Surgeons:

The Hidden Complication We Rarely Discuss Safdar N. Khan, MD

Spine surger y is uniquely rewarding. It restores function, relieves pain, prevents neurological decline, and occasionally saves lives. Yet, every spine surgeon eventually encounters an adverse event that remains vividly etched in memor y long after the patient has left the hospital. A postoperative neurological deficit, an implant malposition, a vascular injury, an unexpected paralysis, a pseudarthrosis, or even a technically flawless procedure followed by an unforeseen complication can profoundly affect the operating surgeon.

W hile much attention is appropriately focused on the patient—the primary victim of an adverse outcome—far less attention is directed toward the surgeon. The concept of the “second victim,” first described by Wu in 2000,1 recognizes that healthcare professionals involved in adverse patient events frequently experience guilt, shame, anxiety, self-doubt, and emotional distress.

These reactions may persist for months or years and can influence future clinical decision-making, professional satisfaction, and personal well-being.

Although second victim syndrome (SVS) has been increasingly recognized across medicine, it is particularly relevant to spine surgery, where technical complexity, high

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patient expectations, and potentially devastating complications create a fertile environment for ps ycholog ica l i nju r y a mong surgeons.

Todd J. Albert, MD

Why Spine Surgeons Are Vulnerable Several characteristics of spine surger y place practitioners at elevated risk for experiencing SVS. First, spine surgery carries substantial stakes. Few specialties possess the capacity to improve or worsen neurological function so dramatically. Even rare complications may result in lifelong disability, making adverse outcomes emotionally difficult for surgeons to process.

Second, spine surgeons often develop long-standing relationships with patients.

Unlike trauma or emergency procedures where interactions may be brief, elective spine surgery frequently involves months of consultation, imaging review, shared decision-making, and postoperative follow-up.

W hen complications occur, the surgeon often feels a personal sense of responsibility that extends beyond the technical aspects of the operation.

Third, t he culture of surger y historica lly rewards perfect ionism. Surgeons

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are trained to anticipate problems, avoid errors, and maintain composure under pressure. While these attributes contribute to excellent patient care, they may simultaneously discourage ack nowledgment of emotional distress. As a result, many surgeons internalize complications and suffer in silence.

The Emotional Impact of Adverse Events Recent reviews have demonstrated that surgeons experiencing SVS commonly report guilt, anxiety, shame, sadness, insomnia, loss of confidence, and intrusive thoughts related to adverse events. Some surgeons describe repeatedly replaying operative details in an attempt to identify what could have been done differently. Others report avoidance behaviors, reluctance to perform similar procedures, or increased anxiety before surgery.

The emotional burden may be particularly pronounced among spine surgeons because complications often involve outcomes that directly challenge professional identity. A surgeon who views technical excellence as a core component of self-worth may struggle to reconcile an adverse event with personal expectations.

Importantly, these reactions are not limited to preventable errors. Complications inherent to spine surgery—even those occurring despite appropriate care and sound judgment—can trigger similar emotional responses. In many cases, t he surgeon experiences guilt regardless of whether objective fault exists.

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Consequences for Surgeons and Patients The effects of SVS extend beyond emotional discomfort. Persistent psychological distress may contribute to burnout, compassion fatigue, sleep disturbance, depression, and, in severe cases, symptoms resembling post-traumatic stress disorder. Systematic reviews suggest that adverse patient events can have substantial professional and psychological consequences for surgeons, influencing career satisfaction and long-term wellness.

The downstream impact on patient care may also be significant. Surgeons affected by unresolved SVS may practice more defensively, avoid complex cases, hesitate during critical decision-making, or withdraw from challenging but appropriate surgical interventions. Conversely, some may overcompensate by becoming excessively risk tolerant in an effort to “prove” competence. Neither response benefits patients.

Recognizing and addressing SVS therefore represents not only a wellness initiative but also a patient-safety imperative.

Morbidity and Mortality Conferences: Opportunity or Threat?

Few educational activities have shaped surgical culture more than morbidity and mortality (M&M) conferences. Ideally, M&M conferences promote transparency, accountability, and learning. However, depending on their structure, they can either facilitate healing or deepen psychological injury.

Historically, some conferences emphasized individual blame rather than systems analysis. Public criticism may intensif y

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feelings of shame and isolation among affected surgeons. Conversely, modern patient-safety frameworks emphasize rootcause analysis, systems improvement, and shared learning.

For spine surgeons, the challenge is maintaining rigorous self-examination without creating an environment that discourages vulnerability or openness. Educational rigor and psychological safety are not mutually exclusive goals.

Building a Culture of Peer Support Evidence suggests that peer support represents one of the most effective interventions for second victims. Surgeons consistently identify colleagues who understand the realities of operative practice as their most valuable source of support following

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adverse events. Structured peer-support programs have demonstrated favorable effects on departmental culture and surgeon well-being.

Spine surgery societies and training programs should consider formal mechanisms to support surgeons following major complications. Such programs might include: • Peer-support networks • Confidential debriefing pathways • Wellness champions within departments • Faculty training regarding SVS recognition • Resident and fellow education regarding coping strategies Importantly, these resources should be viewed as professional development tools rather than signs of weakness.

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Implications for Spine Training The nex t generat ion of spine surgeons must be prepared not only for technical challenges but also for the emotional realities of surgical practice. Residents and fellows routinely witness complications, patient deaths, and diff icult outcomes.

Yet formal education regarding emotional recovery remains uncommon. As a result, many trainees conclude that successful surgeons simply do not experience distress. This perception is inaccurate and potentially harmful.

Facult y who openly discuss complicat ions, uncer taint y, and personal ex periences with adverse outcomes can help nor m a l i z e t hese c onver s at ion s. Suc h transparency may improve resilience while reducing stigma associated with seeking support.

Moving From Survival to Growth Experiencing an adverse event is an unavoidable component of a career in spine surgery. The goal should not be to eliminate emotional responses but rather to develop healthy mechanisms for processing them.

Many surgeons ultimately report that their most difficult cases became powerful catalysts for professional growth. Complications often stimulate quality-improvement initiatives, technical refinement, enhanced communication skills, and greater empathy toward patients and colleagues. The challenge is ensuring that surgeons reach this stage of growth rather than remaining trapped in isolation, self-blame, or burnout.

Conclusion SVS is a common but underrecognized consequence of spine surgical practice. The emotional burden of adverse events affects surgeons at every stage of their careers and has implications for personal well-being, professional longevity, and patient care. As the spine community continues to prioritize physician wellness, SVS deserves recognition as a significant occupational hazard of our profession. Complications may be inevitable, but suffering alone should not be.

Creating a culture that promotes psychological safety, peer support, and open discussion of adverse events may ultimately benefit not only surgeons but also the patients they serve. l

References 1. Wu AW. Medical error: the second victim. BMJ. 2000;320:726–727.

2. Han K, Bohnen JD, Peponis T, et al. The surgeon as the second victim? Results of the Boston Intraoperative Adverse Events Surgeons’ Attitude (BISA) study.

J Am Coll Surg. 2017;224:1048–1056.

3. Scott SD, Hirschinger LE, Cox KR, et

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al. The natural history of recovery for the healthcare provider “second victim” after adverse patient events.

BMJ Qual Saf. 2009;18:325–330.

4. Chong RIH, Yaow CYL, Chong NZY, et al. Scoping review of the second victim syndrome among surgeons: understanding the impact, responses, and support systems. Am J Surg. 2024;229:5–14.

5. Bryan J, Ketley A, Cavanagh K, et al.

Second victim syndrome in surgeons: systematic review and meta-analysis of the impact of adverse events on surgeons. Br J Surg. 2025;113(1):znaf258.

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From the ¹Department of Orthopaedic Surgery at Rush University Medical Center in Chicago, Illinois, and 2MedStar Health Orthopedics at MedStar Georgetown University Hospital in Washington, D.C.

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Private Equity in Orthopedics and Spine Surgery 10 Years Later

Puranjay Gupta1

Private equity (PE) has become a major force in physician-practice consolidation across the United States. Between 2012 and 2021, annual PE-backed physician practice acquisitions increased dramatically, accompanied by rapid expansion in the number of acquired practice locations and affected metropolitan markets.1,2 Although consolidation has occurred across nearly every specialty, orthopedics and spine surgery remain particularly attractive because of their procedural volume, ancillary revenue opportunities, and continued fragmentation of private practice.

Despite ongoing consolidation, orthopedics remains more independent than many other specialties. In 2024, more than half of orthopedic surgeons still reported working within private practice models, even as physician ownership declined nationally.3 This balance between fragmentation and profitability has allowed PE firms to continue targeting musculoskeletal care.

The debate surrounding PE in orthopedics has also evolved. While earlier discussions focused on whether PE would meaningfully enter the specialty, current discussions focus on the long-term implications of PE ownership for physician autonomy, costs, access, workforce stability, and the sustainability of care delivery models. Existing evidence suggests outcomes are variable and depend

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heavily on governance structure, debt burden, physician alignment, and integration strategy.

Why Orthopedics and Spine Remain Attractive Musculoskeletal disease affects Aditya Mazmudar2 a substantial proportion of the U.S. population and continues to increase alongside population aging. Lumbar fusion utilization alone has risen markedly over the past 2 decades, particularly among elderly patients, while Kern Singh, MD1 aggregate hospital costs for spine procedures continue to escalate.4 At the same time, orthopedic and spine surgery have increasingly shifted toward ambulatory surgery centers (ASCs). Medicare-certified ASC utilization continues to grow, and outpatient spine surgery volume has expanded rapidly over the past decade.5 Lower facility costs compared with hospital outpatient departments create strong payer incentives for continued outpatient migration while simultaneously increasing the financial value of ASC ownership.

Orthopedic groups also support substantial ancillary integration. Imaging, physical therapy, pain management, biologics, urgent care, and durable medical equipment can

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Figure 1. Timeline of market evolution in orthopedics.

PRACTICE MODELS

all be incorporated within musculoskeletal platforms. These ancillary services allow vertically integrated systems to retain referrals internally and diversify revenue streams beyond procedural reimbursement alone.

Evolution of the Market Early orthopedic consolidation was initially regional rather than nationally coordinated (Figure 1). A study evaluating orthopedic practice acquisitions between 2010 and 2017 found relatively limited PE involvement, with most transactions involving buyers and sellers in the same state.6 However, PE participation accelerated considerably beginning around 2017. Subsequent studies demonstrated rapid expansion in orthopedic acquisitions, with

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many occurring between 2017 and 2021 as firms pursued platform-and-add-on growth strategies.7,8 This period represented the major platform-building phase of orthopedic PE. Investors consolidated practices into management-services organizations (MSOs), centralized administrative operations, and expanded ASC ownership and ancillary integration. More recently, the market has shifted toward secondary recapitalizations, bolt-on acquisitions, and operational integration rather than the formation of entirely new platforms.

Regulatory scrutiny has simultaneously increased. In 2024, federal agencies, including the Federal Trade Commission, Department of Justice, and US Department of Health and Human Services, initiated a cross-government inquiry into healthcare consolidation and PE-backed roll-up strategies.9 Increased oversight reflects growing concern regarding pricing power, referral control, and the impact of consolidation on competition.

What PE Offers Practices PE-backed transactions generally promise physicians several advantages: immediate liquidity, operational support, relief from administrative burdens, and access to capital for ASC expansion, technology acquisition, recruiting, and infrastructure development.

These partnerships may also improve negotiating leverage with payers and vendors.

Such benefits are particularly relevant in orthopedics, where reimbursement pressures, staffing shortages, and increasing operational costs have challenged smaller independent groups. In some cases, PE-backed MSOs may allow practices to remain operationally inde-

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pendent while gaining resources that would otherwise be difficult to obtain on their own.

What Current Evidence Shows The literature evaluating PE ownership in healthcare remains mixed, though cost trends are more consistent than quality trends. Systematic reviews have generally found that PE ownership is associated with increased spending and utilization, while evidence of improved quality outcomes remains limited.10,11 Price escalation appears to be one of the clearest findings. Studies evaluating PE-acquired physician practices have demonstrated increases in healthcare spending and professional fees following acquisition.11 Similar trends in other procedural specialties suggest that consolidation may increase bargaining leverage and reimbursement rates more reliably than it improves efficiency.

Workforce stability also remains an area of concern. Studies of PE-acquired physician practices have demonstrated higher physician turnover and repeated secondary buyouts occurring within relatively short timeframes.12,13 These findings raise questions regarding long-term organizational stability and physician retention.

Implications for Spine Surgery Spine surgery occupies a particularly important role within PE-backed musculoskeletal plat-forms because it combines high procedural reimbursement with opportunities for ASC migration, imaging, physical therapy, and procedural pain integration. However, at the same time, inflation-adjusted Medicare

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reimbursement for common spine procedures has steadily declined over the past 2 decades despite increasing utilization.14,15 This reimbursement environment increases pressure to capture ancillary and facility revenue while improving operational efficiency.

Recent analyses demonstrate ongoing PE activity in spine surgery specifically, including full-practice buyouts concentrated in rapidly growing, commercially favorable markets.16 While ASC-based spine programs may improve scheduling efficiency, streamline perioperative work-flows, and lower facility costs, concerns remain that financial incentives could influence site-of-service decisions or procedural expansion.

The Surgeon Perspective Physician attitudes toward PE remain divided. Some surgeons view PE partnerships as practical solutions for succession planning, liquidity, recruitment, and administrative support. Others express concern about the loss of autonomy, pressure to meet productivity targets, and reduced influence over longterm practice direction. These concerns may disproportionately affect younger surgeons.

Traditional partnership pathways may increasingly be replaced by employment-based structures that limit future ownership opportunities. Ultimately, successful partnerships appear less dependent on transaction size and more dependent on governance. Physician leadership, transparency in MSO structures, sustainable leverage, and preservation of clinical decision-making are likely to determine whether PE-backed models remain stable over time.

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Conclusion Private equity is now firmly established within orthopedic and spine surgery. Its expansion has prov ided practices w it h capital, operational infrastructure, and scale during a period of rising costs and declining reimbursement. However, PE involvement has also been associated with increased healthcare spending, physician turnover, repeated recapitalization cycles, and ongoing concerns regarding autonomy and long-term incentives.

For orthopedic and spine surgeons, PE should not be viewed as inherently beneficial or harmful. Rather, it represents a financial structure with predictable incentives that may produce markedly different outcomes depending on governance, debt structure, physician alignment, and operational priorities. As consolidation continues, the long-term legacy of PE in musculoskeletal care will likely depend less on acquisition activity itself and more on whether these platforms prioritize durable clinical systems or short-term enterprise valuation. l

References 1. Abdelhadi O, Fulton BD, Alexander L, Scheffler RM. Private Equity–Acquired Physician Practices And Market Penetration Increased Substantially, 2012–21.

Health Affairs. 2024;43(3):354-362.

2. Scheffler RM, Alexander L, Fulton BD, Arnold DR, Abdelhadi OA. Monetizing Medicine: Private Equity and Competition in Physician Practice Markets. Antiturst Institute. July 10, 2023. https://www.antitrustinstitute. org/wp-content/uploads/2023/07/ AAI-UCB-EG_Private-Equity-I-Physician-Practice-Report_FINAL.pdf 3. Kane CK. Physician Practice Characteristics in 2024: Private Practices Account for Less Than Half of Physicians in Most Specialties.

AMA Policy Research Perspectives. https://www.ama-assn.org/system/ files/2024-prp-pp-characteristics.pdf 4. Martin BI, Mirza SK, Karamian BA, et al. Cost and utilization trends of lumbar fusion. JAMA Netw Open. 2026;9(3):e260452.

thopaedic surgery practices in the United States. J Am Acad Orthop Surg Glob Res Rev. 2021;5(12):e21.00162-00168.

7. Boddapati V, Danford N, Lopez C, Levine W, Lehman R, Lenke L. Recent trends in private equity acquisition of orthopaedic practices in the United States. J Am Acad Orthop Surg. 2022;30(8):e664-e672.

8. Sievers MT, Neevel A, Diaz A, et al.

Private equity investment in surgical care. Ann Surg. 2025;281(1):56-64.

9. Federal Trade Commission. Federal Trade Commission, the Department of Justice and the Department of Health and Human Services Launch Cross-Government Inquiry on Impact of Corporate Greed in Health Care [Press release]. March 4, 2024. https://www.ftc.gov/news-events/ news/press-releases/2024/03/federal-trade-commission-department-justice-department-health-human-services-launch-cross-government

5. Miller AK, Cederman MR, Park DK. Growing utilization of ambulatory spine surgery in Medicare patients from 20102021. N Am Spine Soc J. 2024;17:100314.

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