Elastomeric Auxetic Urogenital Meshes: Exploring Alternatives to Knitted Polypropylene
Abstract
Pelvic organ prolapse (POP or descent of the pelvic organs into the vagina) and stress urinary incontinence (SUI or involuntary loss of urine with effort/exertion, or coughing or sneezing) are common conditions in women that significantly impair quality of life. Beyond injury to the pelvic floor at the time of delivery of a baby and degenerative changes with aging, strenuous activity predisposes women to SUI and POP. Women in the military engaging in regular strenuous physical activity may be at increased risk for developing these disorders. Moreover, as the demographics of the military change with an increasing number of women seeking Department of Veterans Affairs services, it is anticipated that more female Veterans will seek treatment of POP and SUI. When symptoms are mild, women may choose to be treated with physical therapy and/or a pessary -- a device designed to hold the pelvic organs in place. Others may elect to proceed with surgery. The lifetime risk of surgery for either SUI or POP is 20%. Thus, in a group of women who are currently 18 years of age, one in five will undergo surgery for either of these conditions by age 80. Surgery may be performed with a woman s own tissues in which the vagina is reattached to the soft tissues that used to support it or lifted by plicating or tightening the underlying supportive tissues. Unfortunately, 40% of these surgeries will fail by 2 years, driving women to seek additional surgery or to live with their condition. Increasingly, surgeons and patients have turned to biomaterials such as surgical meshes to improve outcomes for women. The latter are synthetic lightweight porous fabrics that have been used in abdominal hernia repairs since the 1930s. These were later adapted for use in POP and SUI repairs such that currently, all meshes used in POP repairs and many SUI meshes are hernia meshes simply remarketed for a different indication. Because of their similarity to hernia meshes, prolapse and incontinence meshes have been introduced into the market with little to no premarket testing. Thus, companies could begin marketing and selling a product at a very low cost. For this reason, there was no motivation to develop a mesh specifically for the mechanical and physiologic needs of the vagina and the pelvic organs. When implanting a foreign material such as a mesh into a patient, the surgeon seeks a product that will have the least amount of material in contact with the host while maintaining the mechanical properties to optimize tissue ingrowth for maximal support. Thus, surgeons favor large pore materials. Mesh pores of > 1 mm are needed for optimal tissue ingrowth. Unfortunately, as opposed to what occurs in abdominal hernia repairs in which the forces in the abdomen act to keep mesh pores open, the forces in the pelvis cause pores to collapse, often far less than 1 mm. This results in an increase in mesh burden (more material per unit area), poor tissue integration, and walling off of the mesh with a fibrous capsule, thereby increasing the risk of complications. Here we propose to develop a mesh designed specifically for the biomechanical, anatomical, and physiologic needs of the vagina. Our mesh will be designed to behave auxetically, that is, its pores expand instead of collapse with loading; and it will be made from an elastomeric polymer such that it acts more similarly to the vagina and the soft tissues supporting it. We hypothesize that these novel elastomeric, auxetic prolapse meshes will evoke improved tissue integration and preserve vaginal function relative to current commonly used polypropylene prolapse meshes. The novel mesh design overcomes the problems associated with unstable pore geometries that characterize current polypropylene meshes. For cost-effectiveness, we have designed the study so that in the first aim of the grant, we will develop the mesh and test it using advanced computational modeling. Once a prototype is developed
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 31, 2017
- Source ID
- W81XWH1610133
Entities
People
- Pamela Moalli
Organizations
- UPMC Magee-Womens Hospital
- United States Army