Skeletal Maturity and Segmental Spinal Mobility Predict Successful Vertebral Growth Modulation by Vertebral Body Tethering - Project Summary: Over 16,0000 children in the US are hospitalized for treatments of their spinal deformities. The current surgical standard of care for these conditions is an instrumented posterior spinal fusion. These procedures are expensive (>$100,000) and as they “fuse” the spine they result in loss of spinal growth and mobility. Vertebral Body Tethering i(VBT) is a promising vertebral growth modulating surgical technique that attempts to harness the body’s own growth potential to correct spinal deformities. Despite VBT’s promising benefits, predicting which patient might benefit most from the procedure has been challenging. This project seeks to further refine a computational based surgical decision tool, using novel surgical devices and large animal model. The objective of the current proposal is to incorporate differences in growth potential (skeletal maturity) and vertebral segment mobility (“curve stiffness”) elucidated in our animal model, into our computational model so that the computational model can be used pre-operatively or intra-operatively to inform surgical decision-making using patient specific data. The long-term goal of this project is to provide personalized, vertebral-level by level strategies in correcting spinal deformities that maximize vertebral growth modulation and minimize the use of spinal fusion. We will accomplish this through the following aims: Aim 1: To characterize the maturity-related changes in the hyperkyphotic porcine vertebral physis and their effect on the sensitivity to vertebral tether load. Hypothesis: The vertebral physis will thin and stiffen with age, becoming less sensitive to mechanical load. Approach: Porcine vertebral phases of different maturity will be characterized and growth modulation response to VBT will be measured. Aim 2: To incorporate skeletal-maturity related data into our computational model and then test its ability to account for independent differences in vertebral segment mobility. Hypothesis: Growth modulation following VBT is directly related to vertebral segment mobility independent of skeletal maturity. Approach: Computational modeling throughout clinically relevant pre-operative and post-operative disc geometries will be performed; a subset of scenarios will be surgically reproduced to assess the computational model’s predictions and further refine parameters if necessary Aim 3: To translate our computational model into a clinically predictive tool to guide operative intervention. Challenge: To obtain pre-operative and intra-operative data for our computational model to allow clinical predictions of vertebral endplate stress to guide treatment. Together these aims will further elucidate the effects that skeletal maturity and vertebral segmental mobility have on vertebral growth modulation and allow translation of our research-based computational model into a predictive clinical tool. This will allow better patient and vertebral level selection, minimize unnecessary revision surgery, and limit the use of growth- and motion- eliminating spinal fusions.
