Based on the growing evidence within our literature, mesh is clearly needed for long-term success for the repair of anterior/apical defects. Clear credentialing and clinical privilege criteria policies are long overdue. Current data are rapidly growing, with level I studies completed that demonstrate that when transvaginal mesh-augmented repair is used in appropriately selected patients for the repair of pelvic organ prolapse, the procedure has a favorable risk/benefit ratio when compared with suture repair. This article highlights the evolving clinical-based experiences of the authors that are primarily grounded in reality-based medicine with the consideration and incorporation of evidence-based medicine.
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There is a growing body of evidence supporting the fact that in order to achieve long term durability in anatomical repair of anterior/apical defects the use of synthetic mesh augmentation is necessary.
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Although the ideal mesh is yet to be developed, current materials pose minimal risk to patients when properly implanted via a transvaginal route.
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Developing and propagating surgeon’s expertise to perform transvaginal mesh surgery is no doubt our greatest challenge.
Introduction
Never before has there been more attention, if not intense debate, surrounding the various approaches to reconstructive pelvic surgery. The recent public health announcement (PHA) release from the Food and Drug Administration (FDA) regarding the use of transvaginal mesh no doubt rekindled the suture repair versus mesh augmentation discussion. Some of this activity is fueled by the age of information where there is almost instantaneous and widespread dissemination of each and every opinion. Further confounding factors are not only the blogging by patients but also the heightened legal climate scrutinizing both the pharmaceutical and medical device industry. All of this occurs within the backdrop of the expanding challenges facing effective surgical training and medical education beyond residency or fellowship to keep pace with the advances in surgical innovation and related technologies. This article highlights the evolving clinical-based experiences of the authors that are primarily grounded in reality-based medicine with consideration and incorporation of evidence-based medicine.
Demographic factors are influencing the expectations and subsequent needs that female patients have regarding their overall pelvic health. Women are not only living longer than ever before but are also adopting more active and robust lifestyles in their senior years. Pelvic organ prolapse (POP) is the hidden epidemic. Demographic studies have shown that women aged more than 80 years are the fastest growing population segment in the United States and Canada. Over the next 30 years, the rate of women who will seek treatment of POP will double. As a result, the sustained biomechanical and physical challenges to the pelvic support structures continue to exceed that experienced by women decades ago. More and more women continue to enter (and remain) in the workforce of physically demanding occupations. Further amplifying risk factors are the epidemic of obesity, history of tobacco exposure, and general reluctance to change delivery practices to mitigate obstetric trauma. Furthermore, basic science research has demonstrated that patients with POP have structurally altered collagen, elastin, laminin, and smooth muscle. All of these demographic, genetic, or environmental factors have challenged the durability of traditional suture-based native tissue repair and created the impetus for pelvic reconstructive surgeons to seek the advantages of mesh-augmented repair.
How have we been doing with our suture repair procedures?
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There is an 11.2% lifetime risk of surgical intervention.
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Twenty-nine percent to 40% of reconstructive procedures require surgical reintervention for failure within 3 years.
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Sixty percent of recurrences are at the same site, most being the anterior compartment.
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A total of 32.5% occur at a different site because of an unmasking of an occult support defect.
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Reoperation remains the beginning of a larger issue because women often settle with being not as bad as before , not wanting to go through surgery again.
The rationale behind the use of mesh-augmented repair
The use of mesh materials in the repair of abdominal wall hernias has been proven to be substantially superior to suture-based repairs, with an associated significant decrease in the recurrence rate when mesh materials are used. Obviously, the female pelvis is substantially different in many aspects when compared with the abdominal wall. Nonetheless, one needs to only consider the basic biophysical model of a human abdominal pelvic cavity to realize the challenge facing any nonmesh repair of the pelvic floor. As a result of our upright biped posture, the abdominal-pelvic cavity in humans is basically a mostly vertical-orientated, cylindrical-shaped body cavity filled with fluid and semisolid or gelatinous structures in which outward and downward vector forces are transmitted as a result of upright posture, diaphragmatic excursions, and gravity. Defects of the nondependent ventral surface of this cylinder, which is composed of dense, regular, connective tissue, carries a high recurrence rate with suture-based repair when compared with mesh repair, thus clearly establishing the medical necessity for the use of mesh. Therefore, it seems highly implausible that in the most dependent aspect of this vertical cylindrical abdominal-pelvic cavity (the pelvic floor), in which there is mostly loose, irregular, connective tissue, suture-based repair will be able to provide durable anatomic success. This challenge is compounded by the loss of spinal curvature with the aging process, which had served to promote deflection of these downward force vectors, as well as age-related weakening of the levator ani muscle group, which had provided a dynamic trampoline under the connective tissue structures supporting the pelvic organs.
Contributing factors to surgical failure:
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Anatomic
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Denervation, widening of levator hiatus, connective tissue damage
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Tissue Factors (collagen content and structure)
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Genetics, race, age, concomitant disease (connective tissue, diabetes mellitus and so forth)
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Environmental Factors
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Chronic straining, cough, smoking, nutrition, obesity, medications
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Surgical Factors
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Poor choice/execution of procedure, failure to address all defects, suture failure, inadequate convalescence.
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We must also recognize that after surgical repair, connective tissue healing or scarring does not replace or add tensile strength back to the original prefailure or nonprolapsed state. Thus, over time, suture repair will only eventually fail to restore and maintain normal anatomic position and function in many patients. In the anterior compartment, this high failure rate with suture repair has been well documented in several well-designed surgical trials.
As mentioned, the vagina does have unique differences when compared with the abdominal wall. Some of these differences challenge both the material scientist bioengineers and the implanting surgeon.
Unique considerations to the vagina in the use of mesh-augmented repair
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Surgical site cannot be sterilized
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Relatively thin tissue overlay with no real fascial layer
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Attachment sites are difficult to surgically access
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Complex 3-dimensional architecture and vector forces
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Subjected to great forces with little or no bony reinforcement (and often poor pelvic floor muscle support)
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Must remain pliable for
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Surrounding pelvic organ filling/emptying
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Sexual function.
- ○
The rationale behind the use of mesh-augmented repair
The use of mesh materials in the repair of abdominal wall hernias has been proven to be substantially superior to suture-based repairs, with an associated significant decrease in the recurrence rate when mesh materials are used. Obviously, the female pelvis is substantially different in many aspects when compared with the abdominal wall. Nonetheless, one needs to only consider the basic biophysical model of a human abdominal pelvic cavity to realize the challenge facing any nonmesh repair of the pelvic floor. As a result of our upright biped posture, the abdominal-pelvic cavity in humans is basically a mostly vertical-orientated, cylindrical-shaped body cavity filled with fluid and semisolid or gelatinous structures in which outward and downward vector forces are transmitted as a result of upright posture, diaphragmatic excursions, and gravity. Defects of the nondependent ventral surface of this cylinder, which is composed of dense, regular, connective tissue, carries a high recurrence rate with suture-based repair when compared with mesh repair, thus clearly establishing the medical necessity for the use of mesh. Therefore, it seems highly implausible that in the most dependent aspect of this vertical cylindrical abdominal-pelvic cavity (the pelvic floor), in which there is mostly loose, irregular, connective tissue, suture-based repair will be able to provide durable anatomic success. This challenge is compounded by the loss of spinal curvature with the aging process, which had served to promote deflection of these downward force vectors, as well as age-related weakening of the levator ani muscle group, which had provided a dynamic trampoline under the connective tissue structures supporting the pelvic organs.
Contributing factors to surgical failure:
- •
Anatomic
- ○
Denervation, widening of levator hiatus, connective tissue damage
- ○
- •
Tissue Factors (collagen content and structure)
- ○
Genetics, race, age, concomitant disease (connective tissue, diabetes mellitus and so forth)
- ○
- •
Environmental Factors
- ○
Chronic straining, cough, smoking, nutrition, obesity, medications
- ○
- •
Surgical Factors
- ○
Poor choice/execution of procedure, failure to address all defects, suture failure, inadequate convalescence.
- ○
We must also recognize that after surgical repair, connective tissue healing or scarring does not replace or add tensile strength back to the original prefailure or nonprolapsed state. Thus, over time, suture repair will only eventually fail to restore and maintain normal anatomic position and function in many patients. In the anterior compartment, this high failure rate with suture repair has been well documented in several well-designed surgical trials.
As mentioned, the vagina does have unique differences when compared with the abdominal wall. Some of these differences challenge both the material scientist bioengineers and the implanting surgeon.
Unique considerations to the vagina in the use of mesh-augmented repair
- •
Surgical site cannot be sterilized
- •
Relatively thin tissue overlay with no real fascial layer
- •
Attachment sites are difficult to surgically access
- •
Complex 3-dimensional architecture and vector forces
- •
Subjected to great forces with little or no bony reinforcement (and often poor pelvic floor muscle support)
- •
Must remain pliable for
- ○
Surrounding pelvic organ filling/emptying
- ○
Sexual function.
- ○
The construct of the mesh implant
In addition to the knowledge of pelvic anatomy, it is also important to understand the properties of the individual mesh materials being used.
Characteristics of the ideal prosthetic implant
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Biocompatible and chemically inert
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Does not induce an inflammatory response
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Not physically modified by tissue fluids
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Nonallergenic
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Noncarcinogenic
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Resistant to mechanical stress and infection
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Can be manufactured in the required shape for patients and can be sterilized
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Can prevent adhesion formation over the surfaces in direct contact with viscera
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Better in vivo response than autologous tissue
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No detrimental effect on pelvic function.
Synthetic mesh properties to consider include the following: the core material of the filaments used to construct the mesh, mesh structure (mono vs multifilament; knitted vs woven), pore size, rigidity, elasticity, tensile strength or burst strength, thickness, and total mesh content per unit area.
Of these parameters, pore size is essential when considering bacterial infection; generally, a pore size of more than 75 mm is desirable to allow the passage of leukocytes that are 9 to 15 μm in size and macrophages that are 16 to 20 μm in size. The problem with weaves and smaller pore sizes is that bacteria (on the order of <1 μm in size) can pass into the material but the hosts defense mechanisms (leukocytes and macrophages) cannot. The classification system by Amid and colleagues is commonly used as the standard for porosity. Currently, most materials used in transvaginal placement are type I (macroporous and monofilamentous). Microporous materials can increase the rate of infection (often thought to be subclinical and perhaps related to exposure development) and can lead to graft encapsulation rather than graft integration.
Additional considerations for type I materials
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Weight (gram/square centimeter)
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Flexural rigidity (milligram/centimeter)
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Elasticity (percentage)
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Inflammatory response
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Degree of contraction (percentage)
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Porosity (total percentage)
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Softness (in vitro/vivo).
Most recently, the importance of changes in the biomechanical stimulus of the host tissue as a response to an implant has been recognized. This alteration in normal mechanical stimuli needed for surrounding host cell viability has been well described in the orthopedic literature as stress shielding. It has now been identified as a potential contributing factor in the outcome of mesh-augmented repairs. This phenomenon occurs when surrounding host cells, such as myocytes and fibroblasts, are overprotected from normal physiologic vector forces that would stimulate cell growth and proliferation. As a result, when these cells are shielded from a desired biomechanical stimulus, they experience degeneration and eventual cell death. This finding sheds light on potential sources of certain complications, such as delayed exposures associated with mesh use. It also adds insight on further material science development in the biochemical properties of materials that may help avoid stress shielding ( Figs. 1 and 2 ).
