Date of Award

12-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Bioengineering

Advisor

Melinda K. Harman, Ph.D.

Committee Member

Alexey Vertegel, Ph.D.

Committee Member

B. Todd Heniford, MD

Abstract

Abdominal hernia repair is the most commonly performed general surgical procedure, with synthetic surgical mesh commonly used to buttress the defect in the abdominal wall. A majority of surgical mesh is made from Polypropylene (PP), which has been shown to invoke a foreign body response as long as the material remains in the body. Complications such as chronic pain require further investigation of mesh performance in hernia repair to better understand how performance differs for various surgical mesh materials. The broad objective of this thesis is to quantitatively characterize surgical mesh after exposure to human physiology in an in-vivo environment. This objective will be accomplished through three aims. The purpose of Aim 1 is to develop a mechanical testing protocol suitable for pristine and explanted surgical mesh. The purpose if Aim 2 is to establish a registry of explanted surgical mesh obtained after in-vivo function to overcome the lack of available explanted mesh for testing. The purpose of Aim 3 is to compare mechanical properties of pristine and explanted surgical mesh by quantifying mesh stiffness and compliance. Through collaboration with a regional medical center, a surgical mesh registry was established and 102 explants were received. After removing formalin-fixed tissue from the mesh, a subset of two different types of polypropylene (PP) surgical mesh, namely Composix E/X (heavyweight PP) and Ultrapro (lightweight PP) were selected for testing. Mechanical testing fixtures and testing protocols were developed to assess the mechanical properties of the mesh, including a uniaxial tensile test (ASTM D5035) and a slot test (ASTM D6828). Results of these tests show that Composix E/X was found to have become stiffer after in-vivo exposure, while Ultrapro had become less stiff. Compared to pristine, unused mesh, explanted Composix E/X mesh was significantly stiffer under a tensile load. In the slot test, work required to push the mesh through the slot until the peak load was reached was significantly higher for Composix E/X (heavyweight PP), but not for Ultrapro (lightweight PP). Future testing of different types of explanted surgical mesh having various polymer materials, weights, pore sizes, and other characteristics is possible using the testing methods developed in this thesis and applied to explanted surgical mesh. This will provide additional metrics for comparison of mesh characteristics and clinical performance.

Included in

Engineering Commons

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