Dr. Antonio Valdevit Stevens Institute of TechnologyStevens Institute of Technology Affiliate Assistant Professor Dr. Antonio Valdevit was selected as a finalist for the New Investigator Recognition Awards (NIRA) competition at the 7th Combined Meeting of the Othopaedic Research Societies (CORS). The meeting, to be held October 16-20, 2010 in Kyoto, Japan, gathers orthopedic researchers from across the globe to discuss musculoskeletal issues.

Valdevit’s poster, “New Method for Performance Analysis of Pedicle Screw Designs” will vie with 19 other finalists for one of five cash prizes. The work stems from Valdevit’s doctoral dissertation, which was conducted at Stevens, The Innovation UniversityTM.

Approximately 200,000 spinal fusions are performed annually. The procedure results in the boney union of two vertebral bodies via rigid stabilization. The stability is achieved through the use of spacers in the front and a combination of rods and screws in the back. To firmly anchor the screws, the surgeon places them in the pedicle of the vertebra. Traditionally, pedicle screw designs have been compared using static pullout. While pullout techniques are standard, they are not clinically relevant, because such a loading condition does not occur in the body. Further, pullout tests tend to be insensitive to unique design features as the bone within the vertebral body fails in shear.

In order to better differentiate the characteristics of pedicle screw designs, Valdevit’s work has focused on the use of toggle fatigue testing to evaluate mechanical functionality of these pedicle screws. Highlighted in this study was the use of nonlinear methods in the analysis of the deformation at the screw/bone interface and work generated due to loading. What was found was that not only do these commercial pedicle screws display a similar curve patterns with respect to the cycle number, the mathematical parameters that describe the curves are unique to the screw design. In cases of spinal fusion, a rigid system is required to obtain suitable for fusion. However, overly rigid systems can induce stress shielding and predispose adjacent segments to degeneration. The next step is to correlate the performance characteristics using the methods in this study to clinical data in order to provide clinical validation for current and new designs.

“With the new age of health care that we are to undertake, data such this may become standard practice in the evaluation of spinal instrumentation” Valdevit says.

To learn more about Dr. Valdevit’s work, visit his Faculty Profile.

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