Application Residency Grant Project Section I Project Leader: Teddy E. Kim Credentials: MD, DO,

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1 North Carolina Spine Society Tel: PO Box Fax: Raleigh, NC Application Residency Grant Project Section I Project Leader: Teddy E. Kim Credentials: MD, DO, Male Female Date of birth: 10/19/1985 NC medical license no.: Preferred mailing address ( business or home) City, State, Zip Business Telephone 2423 Hartfield Circle Winston Salem, NC Preferred Fax Cell Phone Teddykim1019@gmail.com Current Residency program Est. completion date Wake Forest 06/2022 Program Director Director s phone Director s Stacey Q. Wolfe, MD sqwolfe@wakehealth.edu Program Coordinator Coordinator s phone Coordinator s Margaret Herring mherring@wakehealth.edu Additional Project Team Members Name Credentials address Jonathan L. Wilson MD, DO, jlwilson@wakehealth.edu Philip J. Brown MD, DO, PhD phibrown@wakehealth.edu Alexander K. Powers MD, DO, apowers@wakehealth.edu John Frino MD, DO, jfrino@wakehealth.edu Carl M. Nechtman MD, DO, cnechtma@wakehealth.edu Section II Personal Statement: Please indicate how this grant, if funded, will help toward your career goals and intended area of specialization. Outline your expected career path and how this aligns with the Residency Research Grant program objectives and criteria. (500 words max.) I have been fortunate enough to begin my neurosurgery training at Wake Forest, an institution with strong emphasis on spine surgery ranging from deformity correction to management of spinal tumors. Learning about the variety of spinal conditions drew my attention to the field and I would ultimately like to pursue a career in spine surgery with plans to pursue a fellowship after completion of residency. One common problem that I noticed early on in residency was the high prevalence of development of proximal junctional kyphosis in patients after spinal fusion. Further research into the matter revealed how little our current understanding was in the pathophysiology of proximal junctional kyphosis. I wanted to develop a solution that would reduce the number of patients that require extension of their fusion construct due to development of proximal junctional kyphosis. While this is a lofty goal, I wanted to get a more fundamental understanding of the problem and decided that a solid understanding in the biomechanics of the spine would provide a clue to the solution. In addition, developing familiarity with the robotic arm that will be used in this project would open future opportunities in developing models for spine research. I believe that further spine research with emphasis in physics and biomechanics will lead to development of solutions to the complex problems we face today. The proposed project is a pilot study with plans to pursue a larger scale study if the model proves to be feasible. However, the potential impact it could make in the field of deformity surgery is immeasurable given the prevalence of proximal junctional kyphosis. In addition, the method of analyzing the spine using the robotic arm is easily applicable to other spinal disease

2 North Carolina Spine Society, p. 2 models and would provide a platform for future research in many different areas of spinal disorders. This research grant will provide me with opportunity to learn the technique that will provide me with more opportunities to answer difficult questions in spine mechanics as I pursue my career in academic neurosurgery. I chose the field of medicine because I wanted to make an impact on people s lives. In addition to direct patient care, the importance of cutting-edge research in having broader impact on patients lives is becoming more evident as I progress in my training. I would like to contribute to the field of neurosurgery by providing potentially practice changing innovation through research based on scientifically sound methods and principles. Section III Details of the proposal Short title Biomechanical analysis of fusion construct with or without utilization of soft tissue sparing percutaneous instrumentation placement techniques at the uppermost instrumented vertebrae. Abstract summary Adult spinal deformity is a highly prevalent disorder commonly addressed with long segment fusion for deformity correction. Long segment fusion is effective at correcting spinal deformity, however, a commonly noted problem is development of proximal junctional kyphosis at the adjacent level between the fused segment and mobile segment. One hypothesis is that preservation of the posterior tension band may reduce the likelihood of developing PJK. This study will make use of a robotic arm to analyze two different techniques of fusing segments of the spine (traditional open technique vs. percutaneous instrumentation technique at the upper three levels). Outline of the problem Adult spinal deformity is a highly prevalent disorder commonly addressed with multilevel fusions for deformity correction 1. Due to the long segment instrumented fusion required to address complex spinal deformity, these surgeries are frequently associated with high complication and revision rates 1. The development of kyphosis at the transition zone between fused and mobile motion segments is one of the most common complications of long segment deformity correction 1. First described by Glattes et al in retrospective review of 81 patients, proximal junctional kyphosis (PJK) is defined as proximal junctional Cobb angle ³10 degrees and at least 10 degrees greater than the preoperative measurement 2. Incidence of PJK ranges between 17% to 62% with most sources reporting rates between 20% and 40% 1 9. No definitive methods have been described to prevent PJK, however the following strategies have been considered: 1) extension of fusion to include levels with baseline segmental kyphosis >5 degrees, 2) decrease instrumentation stiffness, 3) use of composite materials, 4) use of fewer implants, 5) more distal osteotomies, 6) less destruction of the soft tissues at the upper instrumented vertebrae, 7) attempts to achieve optimal sagittal balance, 8) use of transition rods and 9) optimization of post-operative alignment 10. This project will specifically address whether less destruction of soft tissue at the upper instrumented vertebrae levels decreases the rate of development of PJK. State of the art in this field Many strategies have developed to address the issue of PJK although there is no standard recommendation to this date. The importance of preservation of the interspinous and supraspinous ligaments has been recognized as an important strategy in preventing development of PJK 11,12. Cahill et al. demonstrated that increased pressure in the nucleus pulposus resulted in an increase in the angular displacement of the instrumented constructs when the interspinous and supraspinous ligaments were removed using finite element analysis 12. The increased pressure in the nucleus pulposus and increased angular displacement were reduced by leaving the interspinous and supraspinous ligaments intact, which was further improved with the use of transition rods 12. Additional strategies include use of proximal junctional tethering at the uppermost instrumented vertebrae, however detailed biomechanical studies are limited 13. Past research of the applicant in this field None

3 North Carolina Spine Society, p. 3 Open questions Will utilization of soft tissue sparing percutaneous instrumentation techniques at the upper level of a long segment fusion construct reduce the degree of proximal junctional kyphosis? Hypothesis Percutaneous instrumentation techniques compared to traditional open instrumentation at the upper instrumented levels of a long segment fusion will reduce the degree of proximal junctional kyphosis. What are the aims you want to reach with this study? This project will demonstrate reduced degree of PJK at the adjacent level superior to the construct utilizing percutaneous instrumentation techniques with preservation of the posterior tension band. This project will also serve to develop a model for study of adjacent segment disease in cadaveric specimens using the robotic arm that can be utilized in subsequent larger studies. Anticipated results We anticipate a reduced degree of PJK in the specimen where the interspinous and supraspinous ligaments of the uppermost instrumented levels are better preserved using percutaneous instrumentation techniques. Study subjects, specimen or materials The project will entail using robotic arm (Kuka KR-300ultra) and using six axis force-moment sensor along with threedimensional motion analysis of the instrumented construct 14. Two cadaveric spines with preserved soft tissue will be used in the study. One specimen will be instrumented after exposing the entire length of the construct. The lower levels of the second specimen will be instrumented after open exposure, but the top levels will be instrumented using percutaneous screw technique. The instrumented construct will span the same number of levels in both specimens. Sensors will be placed on the vertebral body one level above the superior most level of the construct in addition to the vertebral bodies spanning the entire length of the construct. Motion tracking cameras (NDI 3D Investigator) will be positioned to assess degree of angulation with motion. Effect and outcome variables Degree of motion in reference to a given moment applied to the construct will be measured using pressure sensor and motion analysis using motion tracking cameras (NDI 3D Investigator) and optical sensors. Variables to be measured include stiffness and range of motion in flexion/extension, lateral bending and axial rotation during the robotic testing period. We will measure the degree of kyphosis across the superior margin of the construct at the conclusion of the study to ascertain the degree of proximal junction kyphosis for each construct. We anticipate that the use of a percutaneous instrumentation technique will preserve the posterior tension band and result in reduced PJK when compared to the construct that was placed using open exposure. Methods for taking measurements Hybrid method of compliance testing will be used to test cadaveric spine that is fused using two different techniques as mentioned in the aim and study subject section 14. Two cadaveric spines, one with percutaneous instrumentation technique at the upper instrumented levels and the other with traditional open exposure will be prepared for placement into the robotic arm. Instrumentation will span the same number of levels in both specimens and the spine will be cut at the inferior and superior margins of the construct for placement onto the robotic arm. Posterior soft tissue will be preserved in both models. Optical markers will be placed along the ventral aspect of the vertebral body spanning the length of the construct and one additional level above the construct. The relative functional spinal unit (FSU) motion will be tracked using the optical markers and motion tracking camera (NDI 3D Investigator) 14.

4 North Carolina Spine Society, p. 4 Methods for data management and analysis (including biostatistical check) There will be only one specimen in each surgical group. If the model proves to be feasible, this study will prompt a larger study using multiple cadaveric models for statistical analysis. Estimation of sample size and power One cadaveric specimen will be used in each surgical group. This study is designed to show feasibility of the cadaveric model and provide preliminary data for a larger scale study. Animal model No live animals will be used for this project. Relevance of the project Long segment instrumentation is a commonly used technique for correction of spinal deformity 1. This long segment fusion technique often results in development of proximal junctional kyphosis (PJK) at the junction of the stiff and mobile segments 1. Various surgical techniques and device modifications have been proposed, but there is still no clear understanding of how to prevent development of PJK 12. To this date, there is no biomechanical analysis of PJK in a cadaveric model. The robotic arm has been used to assess stiffness of multiple instrumented spine constructs in other studies 15. This study aims to develop a new method for assessing the development of PJK in a cadaveric model with various spinal instrumentation constructs. Time schedule Fresh cadaveric specimen will be obtained, and instrumentation will be performed on the same day. After placement of the instrumentation using traditional open technique and percutaneous instrumentation at the upper instrumented levels, the specimen will be truncated inferior and superior to the construct and adjacent segment. This truncated specimen will be placed in a mold and secured onto the Kuka robot. Biomechanical analysis of each specimen will be performed the same day and data analyzed for comparison. Relevant literature by the investigators 14. P.J., B., G.J., G., J.D., M., J.L., W. & J.D., S. Hybrid fusion technique of standard pedicle and cortical bone screws in lumbar spine fusion. J. Orthop. Res. (2016). doi: Relevant literature by other authors 1. Kim, H. J. & Iyer, S. Proximal Junctional Kyphosis. Journal of the American Academy of Orthopaedic Surgeons (2016). doi: /jaaos-d Glattes, R. C. et al. Proximal junctional kyphosis in adult spinal deformity following long instrumented posterior spinal fusion: Incidence, outcomes, and risk factor analysis. Spine (Phila. Pa. 1976). (2005). doi: /01.brs Kim, H. J., Lenke, L. G., Shaffrey, C. I., Van Alstyne, E. M. & Skelly, A. C. Proximal junctional kyphosis as a distinct form of adjacent segment pathology after spinal deformity surgery: A systematic review. Spine (2012). doi: /brs.0b013e31826d611b 4. Yagi, M., King, A. B. & Boachie-Adjei, O. Incidence, risk factors, and natural course of proximal junctional kyphosis: Surgical outcomes review of adult idiopathic scoliosis. minimum 5 years of follow-up. Spine (2012). doi: /brs.0b013e31824e Denis, F., Sun, E. C. & Winter, R. B. Incidence and risk factors for proximal and distal junctional kyphosis following surgical treatment for Scheuermann kyphosis: Minimum five-year follow-up. Spine (Phila. Pa. 1976). (2009). doi: /brs.0b013e3181ae2ab2 6. Hassanzadeh, H. et al. Type of anchor at the proximal fusion level has a significant effect on the incidence of proximal junctional kyphosis and outcome in adults after long posterior spinal fusion. Spine Deform. (2013). doi: /j.jspd

5 North Carolina Spine Society, p Kim, H. J. et al. Proximal junctional kyphosis results in inferior SRS pain subscores in adult deformity patients. Spine (Phila. Pa. 1976). (2013). doi: /brs.0b013e b42 8. Kim, Y. J. et al. Proximal junctional kyphosis in adult spinal deformity after segmental posterior spinal instrumentation and fusion: Minimum five-year follow-up. Spine (Phila. Pa. 1976). (2008). doi: /brs.0b013e31817c Lee, J.-H., Kim, J.-U., Jang, J.-S. & Lee, S.-H. Analysis of the incidence and risk factors for the progression of proximal junctional kyphosis following surgical treatment for lumbar degenerative kyphosis: minimum 2-year followup. Br. J. Neurosurg. (2014). doi: / Lau, D. et al. Proximal junctional kyphosis and failure after spinal deformity surgery: A systematic review of the literature as a background to classification development. Spine (2014). doi: /brs Tai, C. L. et al. Biomechanical comparison of lumbar spine instability between laminectomy and bilateral laminotomy for spinal stenosis syndrome - An experimental study in porcine model. BMC Musculoskelet. Disord. (2008). doi: / Cahill, P. J. et al. The use of a transition rod may prevent proximal junctional kyphosis in the thoracic spine after scoliosis surgery: A finite element analysis. Spine (Phila. Pa. 1976). (2012). doi: /brs.0b013e318246d4f2 13. Smith, J. S. et al. Recent and Emerging Advances in Spinal Deformity. Neurosurgery (2017). doi: /neuros/nyw P.J., B., G.J., G., J.D., M., J.L., W. & J.D., S. Hybrid fusion technique of standard pedicle and cortical bone screws in lumbar spine fusion. J. Orthop. Res. (2016). doi: 15. Perry, T. G. et al. Biomechanical evaluation of a simulated T-9 burst fracture of the thoracic spine with an intact rib cage. J. Neurosurg. Spine (2014). doi: / spine13923 Section IV Budget for proposed project period Personnel Surname / First name Academic qualification Effort in % Material Devices, equipment, extension to existing equipment, etc. Cadaver x2 $3000 Supplies Itemize below Instrumentation $0 Rental of equipment Itemize below Kuka Robot $1000 Optical Sensors $500 Motion Sening Camara $500 Total Funding Request (max. $5000): $5000

6 North Carolina Spine Society, p. 6 Section V If selected for participation in the program, the grantee agrees to conduct herself/himself professionally according to the principles of medical ethics and to be governed by the Bylaws of the North Carolina Spine Society. Applicant s signature: Date: Program Director s signature: Date: 1. Completed application form 2. Applicant s CV 3. Completed W-9 form of the recipient organization (IRS W-9) Please sign your completed form and return it along with your CV by , mail or fax to: NCSS, PO Box 27167, Raleigh, NC Fax: ncspine@ncmedsoc.org