Implantation of a synthetic midurethral sling (SMUS) is the most commonly performed anti-incontinence operation in women worldwide. The effectiveness of the SMUS is comparable to that of the historical gold standards--autologous fascial slings and the Burch colposuspension. Much controversy, however, has evolved regarding the safety of this type of sling. Overall, the quality of the studies with respect to assessing risks of SMUS-associated complications is currently poor. The most common risks in patients with SMUS include urethral obstruction requiring surgery (2.3% of patients with SMUS), vaginal, bladder and/or urethral erosion requiring surgery (1.8%) and refractory chronic pain (4.1%); these data likely represent the minimum risks. In addition, the failure rate of SMUS implantation surgery is probably at least 5% in patients with stress urinary incontinence (SUI). Furthermore, at least one-third of patients undergoing sling excision surgery develop recurrent SUI. Considering the additional risks of refractory overactive bladder, fistulas and bowel perforations, among others, the overall risk of a negative outcome after SMUS implantation surgery is ≥15%.

Polypropylene meshes, originally introduced for hernia repair, are presently utilized in several anatomical sites. Several million are implanted annually worldwide. Depending on the device, up to 10% will be excised to treat complications. The excised meshes can provide material to study the complications, however, they have remained underutilized over the last decades and the mechanisms of complications continue to be incompletely understood. The fundamental question as to whether polypropylene degrades in vivo is still debated. We have examined 164 excised meshes using conventional microscopy to search for features of polypropylene degradation. Four specimens were also examined by transmission electron microscopy. The degraded material, detected by its ability to absorb dyes in the degradation nanopores, formed a continuous layer at the surface of the mesh fibers. It retained birefringence, inclusions of non-degraded polypropylene, and showed ability to meld with the non-degraded fiber core when heated by the surgical cautery. Several features indicated that the degradation layer formed in vivo: inflammatory cells trapped within fissures, melting caused by cautery of excision surgery, and gradual but progressive growth of the degradation layer while in the body. Cracking of the degraded material indicated a contribution to clinically important mesh stiffening and deformation. Chemical products of degradation need to be analyzed and studied for their role in the mesh-body interactions. The described methods can also be used to study degradation of other materials. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 237-248, 2017.

The perusal of surgical journals suggests that the etiology and the treatment of hernias are still based on the understanding of a simple mechanical defect, an idiopathic happenstance requiring a reliable hernia repair, preferably with a prosthetic mesh or device. The need for additional elucidation does not constitute an aim that is pervasive in the surgical community or with the corporate manufacturers of surgical implements. This may well be because surgeons are not trained scientists and laboratory workers. Fortunately, several disciplines are injecting a healthy dose of curiosity matched by ingenuity. Among these contributors, we can count anatomists, electron microscopists, biochemists, organic chemists, pathologists, geneticists, and molecular biologists, who have looked at collagen, enzymes, tobacco smoke, congenital diseases, and chromosomal defects. Every aspect of the researchers' work has identified and converged onto a final common organ: collagen. It is the pathological changes in collagen that set the stage for the development of a hernia. The multiple theories on mechanisms of hernia formation have, at last, melded into one single Unified Theory of hernia formation.

The treatment of incisionaI hernias, on occasions, imposes the use of an intraperitoneal prosthesis. Though none of the available biomaterials is entirely satisfactory, the choice often reflects a compromise. Polypropylene and polyester have been associated with bowel obstruction, fistulization and transmigration through a viscus. These problems are almost unknown with e-PTFE. All three however can cause adhesions. On the other hand, the solidity of a repair is a function of the penetration of a prosthesis by fibroblasts and collagen. Polyester and polypropylene manifest such a penetration. e-PTFE less so. The combination of e-PTFE internally and polypropylene externally seems to provide a reasonable composite which has been used in 30 cases in the last six years. During that period no patient presented with an intestinal occlusion or fistula.

The surgical treatment of inguinal and femoral hernias has evolved through several stages to reach a modern and successful era. This success was shared by all our predecessors who contributed some knowledge with respect to anatomy, physiology, and surgery. Although most patients are treated with satisfaction by primary herniorrhaphy, difficult recurrences can also be treated successfully. The special features that characterize the modern treatment of difficult hernias are the preperitoneal approach and the availability of reliable prosthetic materials. Some of the techniques currently available are discussed. They are the femoral umbrella, transversalis fascial replacement, and the fletching. The results have been encouraging. As surgeons, we are behooved to look, assess, and reconsider in order to improve.