Valuable Tools for Spinal Surgery Planning

Background

Adult spinal deformity (ASD), a deviation in the alignment of the spinal column, can significantly affect an individual's quality of life. According to the Hospital for Special Surgery (HSS), patients seeking medical intervention typically fall into one of five categories of deformities: (1) a curvature of the spine from childhood or adolescence that has become more symptomatic in adulthood, (2) an injury-related deformity, (3) a collapsed vertebra caused by osteoporosis, (4) a focal problem that led to degenerative changes to the spine, or (5) a need for revision surgery owing to wear and tear or to the position of a previous fusion.

Medscape recently interviewed Frank J. Schwab, MD, the new Chief of Spine Service at HSS, who developed a descriptive classification for ASD and a software program (Surgimap) to assist surgeons in studying spinal deformities and surgical planning.

Medscape: You developed the first definitive classification of ASD that's become a clinical standard for surgeons worldwide. Can you talk about the Scoliosis Research Society-Schwab Adult Spinal Deformity Classification (Figure 1)?

Figure 1. The Scoliosis Research Society-Schwab Classification of adult spinal deformity.

Dr Schwab: The classification effort surrounding ASD involved many collaborators and took nearly 10 years to establish. As the data began to underline the value as not just a descriptive classification but also one tied to patient-reported function/pain and outcomes of surgery, we partnered with the Scoliosis Research Society. The goal was to ensure that education and dissemination of the work would affect research and clinical care globally.

Figure 2. Example of SRS-Schwab ASD Classification. Patient classified as type L owing to a 41° lumbar curve with apex at L2, a pelvic incidence/lumbar lordosis mismatch (PI-LL) of 20° (PI = 73°, LL = 53°), a pelvic tilt of 27° and an sagittal vertical axis (SVA) of 62 mm.

Today, much work continues in the area of ASD, and the classification has been a tremendously useful tool. Further work will help establish more personalized and detailed guides to patient treatment and optimal surgical strategies.

Medscape: You recently had an exhibit that reviewed recent advances in sagittal spinal alignment and compensatory mechanisms for maintaining balance and optimal targets for surgical procedures. Can you describe your findings?

Figure 3. Sagittal spinopelvic radiographic parameters.

Dr Schwab: Spinal alignment is a rather patient-specific issue, where age and individual morphology are highly relevant in diagnosing and treating deformity. Through the larger study groups, thresholds for surgical targets have been established and the impact of alignment change in patients analyzed. This information is critical in personalizing care and reducing such issues as junctional failure after deformity corrections.

Medscape: You also presented a case study at the exhibit ("Considerations in Cervical Alignment" [Figure 4]) where you described a technique for correcting the "driver of deformity." Could you elaborate on your findings?

Figure 4. Considerations in cervical alignment.

Dr Schwab: Standing alignment from the cervical [vertebrae] down to the feet involves many structures and can be complex to understand. Through collaborative work and large data sets, it has been possible to define which elements of poor alignment are the inherent pathology (or driver) and which elements are compensatory to the underlying principal deformity. This approach is helping us better diagnose and treat patients who many present with neck, upper back, or lower back symptoms related to a global spinal deformity.

Medscape: You mentioned that planning for surgical procedures is a five-step process. What are the five steps you recommend?

Dr Schwab: Of course, there are many different ways to approach the diagnostic analysis and treatment of ASD. In a simplified step-by-step process, we have outlined a consistent methodology that can assist surgeons owing to its pragmatic application.

Step 1 consists of defining the underlying pathologic element in sagittal plane alignment. Step 2 highlights the impact of the pathologic region by removing the compensatory elements (eg, pelvic retroversion), and step 3 consists of defining alignment goals on the basis of age and morphology of the patient (eg, pelvic incidence). Step 4 relates to the surgical strategy (eg, one large or several small osteotomies or use of cages). Finally, step 5 is the intraoperative component of verifying the precise alignment change achieved in relation to the necessary goal of the plan preoperatively.

Medscape: You are also a founder of Nemaris, a company that develops spine measurement and surgical planning software. Can you describe the most recent version of the free software that is available for surgeons?

Dr Schwab: The software was originally developed to assist in measuring radiographs, because most picture archiving and communication systems (PACS) are not designed for the needs of spine surgeons. Over time, the software has evolved to simulate aspects of surgery (eg, osteotomies, cage and screw placement, custom rod contour) and can now connect to various other technologies (eg, PACS, intraoperative navigation/confirmation systems). The software has also become a lot simpler to use, with many automation steps and now a 3D multiplanar reformatting toolkit. Finally, the initial software has developed into a rich sharing platform, with a really useful mobile app that permits taking photos and video and sharing important case-related information with the clinical team.

Medscape: Are you working on any other research at the moment that you would like to share with us today?

Dr Schwab: We are working on several interesting topics around predictive analytics, more personalized and sophisticated planning for surgery to enhance outcomes, and soft-tissue considerations in degenerative and deformity-related pathologies. I've had the great fortune to work with many excellent researchers and surgeons across the world, and innovative approaches to spine care are emerging, with tremendously positive impact on patients.

Frank J. Schwab, MD, has disclosed the following relevant financial relationships:
Serve(d) as a director, officer, partner, employee, advisor, consultant, or trustee for: Zimmer-Biomet, Medicrea, MSD, K2M, NuVasive
Serve(d) as a speaker or a member of a speakers bureau for: Zimmer-Biomet, Medicrea, MSD, K2M, NuVasive
Received a research grant from: DePuy Spine, K2M, NuVasive, Stryker (paid through ISSGF)
Other: Nemaris Inc—board of directors, shareholder

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Cite this: Valuable Tools for Spinal Surgery Planning - Medscape - Jun 14, 2017.