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Development of Deformity Specific Finite Element Models
Start Date: 9/5/2019Start Time: 10:00 AM
End Date: 9/5/2019End Time: 12:00 PM
Event Description
BIOMED Master's Thesis Defense

Development of Deformity Specific Finite Element Models for Surgical Simulation of Anterior Vertebral Body Tether for Treating Scoliosis in Pediatric Subjects

Girish Viraraghavan, Master's Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University
Sriram Balasubramanian, PhD
Associate Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University

Adolescent Idiopathic Scoliosis (AIS) is a three-dimensional (3D) deformity that is characterized by lateral bending and axial rotation of the spine. Severe cases of AIS deformity (Cobb angle>40°) undergo surgical intervention. Recently growth friendly interventions for skeletally immature AIS subjects have shown promising results. Anterior Vertebral Body Tethering (AVBT) is one such growth friendly intervention that provides 3D correction of the deformity along with restoration of range of motion (ROM) of the spine. However, various parameters affect the outcome of this surgery, such as curve location, number of screws and amount of tether tension. Therefore, the objective of this study was to develop and validate a 10-year-old normative pediatric thoracic and lumbar spine Finite Element (FE) model with pelvis that can be used to create deformity-specific AIS FE models to simulate and optimize surgical intervention using AVBT.

Chest and abdominal Computed Tomography (CT) scans were used to create a normative 10-year-old thoracic and lumbar spine FE model with pelvis with age-, and level-appropriate material properties for vertebrae, intervertebral discs and spinal ligaments. This normative FE model was morphed to a 16-year-old Lenke 1AN deformity-specific AIS FE model using dual kriging and used to simulate AVBT surgeries. A total of 48 AVBT simulations were performed with various parametric combinations of number of instrumented levels (2: all and alternate), screw placement (2: lateral and posterior-lateral), applied force levels (3: all, ends only, and apex±1) and tether force (4: 100, 200, 300 and 400 N). Clinical parameters of interest such as Cobb angle, thoracic kyphosis, lumbar lordosis and axial vertebral rotation were computed, and optimal parameter combinations for surgical planning were identified.

Such FE models could serve as valuable pre-operative clinical tools to aid in patient-specific surgical planning and interventional prognosis for AIS spine deformity treatment along with the potential to optimize surgical parameters and reduce surgery times, and thereby minimize the risk to pediatric patients.
Contact Information:
Name: Ken Barbee
Phone: 215-895-1335
Girish Viraraghavan
Bossone Research Center, Room 709, located at 32nd and Market Streets.
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