Dr Robert Bendavid

Mesh Myth Busters

Mesh Down Under conducted a Q and A interview with
Dr Robert Bendavid- lead hernia surgeon at the Shouldice Clinic in Toronto, Canada.

17 July 2018

Q. We've been told that although a surgical mesh implant may be soft and pliable before implantation, once implanted the mesh device can become hard and brittle. Can you confirm if this is correct and clarify what implications this may have for the patients’ wellbeing, especially in the long term?

A. Yes, this is correct but it can also shrink, become displaced, may bundle up and will shed peripheral layers for as long as it is in the human body, most importantly it can erode through adjacent structures. It may take years to manifest itself, but so far, we have 12-20% incidence of such events leading to chronic, severe pain which demands mesh removal.

Q. In 2015 Johnson and Johnson Medical updated the Instructions for Use (IFU) for the TVT Gynaecare range in New Zealand. Our Director General of Health requested that new safety information be added and the IFU was subsequently updated again in 2018. Other than just adding “acute and/or chronic pain”, they also removed "excessive contraction or shrinkage of the tissue surrounding the mesh, vaginal scarring, tightening and/or shortening may occur". What do you think of this?

A. This warning should not have been removed because mesh, whatever its weight, will shrink. Studies have demonstrated that it makes no difference … pore sizes also will make no difference since we know that shrinkage can occur up to 50% and that means that pores will also decrease in size accordingly. The shrinkage is NOT due to the scar tissue but to scar tissue which is dragged by the shrinking mesh. Only in scarring due to third degree burns do you see such scarring which will deform appearance (face, arms, neck). When doing surgery in recurrences which did not have mesh, the dissection is so much EASIER than when mesh is present and the scarring so much more pliant and soft. This IFU is misleading, implying that the “excessive contraction” is due to the scarring of the patient’s tissues. “Shortening and tightening” is also secondary to mesh contraction.

Q. This has been replaced with "over correction i.e. too much tension applied to the tape may cause temporary or permanent lower urinary tract obstruction”. This change in wording could be seen as directing the issue of contraction towards the skills of surgeon. What do you think?

A. The skill of the surgeon has nothing to do with the complication! The best and most competent surgeons in the world will have the complication no matter what the tension is. This problem is similar to what we see in hernia surgery. Complications will appear in some people and not in others. That is where the problem lies. If we knew who these patients were, we could predict the problem and perhaps avoid using mesh in that class of patients. The issue of tension is even more delicate since we have NO MECHANISM of measuring tension. Once the surgery terminated, who is to guarantee that the tension will be the same when the patient wakes up and returns to various degrees of activity! .

Q. Is mesh contraction only a result of the mesh being placed incorrectly by surgeons and the contraction of the surroundings tissues, or is it also the mesh device itself?

A.It is primarily the mesh! We do not see this problem when pure tissues are used. Or even when resorbable meshes have been used. Dr Schlomo Raz or Dr Gerry Blaivas could provide stats which have appeared in a long paper we published together.

Q. You have done a lot of research on mesh degradation and found that nerves grow alongside and into the pores of the mesh. Is it true that the amount of degradation is more significant as time progresses and is nerve entrapment a common problem?

A. Degradation is more marked on time. (The longer the mesh is implanted). It was Dr Vladimir Iakovlev who identified that the thicker the “bark” becomes with time, the more it degrades and becomes shed. It is reported in our articles in HERNIA and in Annals of Surgery. Nerve entrapment is a term which was used in the days before mesh when a surgeon accidentally included a nerve in the suture lines or in a single suture. The condition is soon seen as a complication which is classical. Surgery within a day or two or within a month if there is no improvement, leads to syurgery to identify the nerve trapped, divide it and the problem is taken care of. With mesh, the contact of mesh-nerve leads to erosion as seen in many of our slides and can erode through an entire spermatic cord. Nerves and all and lead to pain. We have discovered neuromas associated with mesh but are not quite sure as to the incidence in general. Nerves also become intimately linked with folding mesh, displaced mesh, bundled mesh, incarcerated into pores all mechanisms which mean tension and erosion of nerve and consequent pain.

Q. Auto-immune issues are becoming more common in patients after implantation once complications arise. Although currently there is limited research into auto-immune issues being attributed to mesh complications, is there any way to test for this and do you think more research in this area is needed?

A. More research is needed. These have been alluded to in many studies but I have not been able to retain the association of a competent immunologist. Many surgeons and patients seem convinced, but at this stage I cannot confirm such a delicate issue, though it certainly may be a reality. Basic studies are needed to jump start such a project. I have tried 3 immunologists … no interest so far. Yet one of them has expressed his concerns!

Q. Can there be particles and leachable substances produced during degradation?

A. Most likely. These are the particles that only companies know of, which I also would like to know more about… such as Zinc, Copper, aldehydes, nonylphenol (an estrogen mimicking product labelled by the FDA as toxic), dyes and stabilizers.

Q. The risk of chronic pain can be exacerbated by device deformation. It has been reported that after implantation the edges of the mesh can curl or fold and bunching of the mesh can occur.  Can you explain why this occurs and how excessive scar tissue can form?

A. The mesh can also shrink and assume strange shapes. Pain per say is probably due to the stress, deformation and erosion into the adjacent nerves. It is all so clear to see, but the profession is acting like the crowds in “The Emperor’s New Clothes” by Hans Christian Andersen … They see nothing!

Q. It has been reported as a known complication of mesh bladder slings and tapes that patients can suffer with voiding difficulties and excessive leaking after implantation.  Can you explain why this happens and whether this is something that happens only immediately or years after implantation?

A. These events can occur immediately or much later. As mesh hardens and shrinks, a sling (or a hammock) with sharp edges, becomes as rigid and sharp as a saw and initiates erosion, cutting and consequently the known events which make mesh objectionable.

Q. We often hear doctors have told patients that “it is only a small amount of mesh that is being used”, or it is “not the same mesh as the ones causing problems”. Clinicians moved away from using heavier weight mesh because of the small pore size and rigidity of the product, yet mesh tapes are still are made of a heavy weight mesh.  What is your response to this?

A. No matter what anyone says, whether it be a surgeon or the industry, polypropylene remains polypropylene only worse … hardened, misshaped, erosive. It is a common strategy of the industry when there is a problem to introduce a change which is meant to correct a deficiency, but in fact does nothing. A pore size on time will shrink, lighter weight still elicits a foreign body response (albeit lessened according to some studies) but the eventual events are all the same. The addition of “barriers” [most often used in hernia mesh implants] which dissolve and disappear in a matter of weeks and months, will lead to a simply delayed complication.

Q. Would you agree there is a dearth of robust information regarding the life-long risk of mesh implants and no real understanding of who will develop complications?

A. Many urogynaecologists are of the same opinion, especially Dr Shlomo Raz in California. The irony, as in hernia surgery, is that there are pure tissue repairs with results which are just as good without similar complications.

Q. There is much discussion about mesh removal and debate about whether a partial or full removal is the best outcome for the patient. Not all patients have the choice or are able to have a full removal of their mesh. Why is the mesh so hard to remove (especially for Trans Obturator tapes) and what are the implications for the patient if only a partial removal is undertaken? 

A. Once scar tissue has infiltrated a mesh and hardens, the latter becomes indistinguishable surgically from scar tissue and any organ it may invade. Removal is often done by feeling the consistency of the mesh. It is like filleting a fish in which you may not get all the bones some of which you may sacrifice for safety, a thing you cannot do with human tissues! 

Q. In regards to the reclassification of the surgical instruments used in SUI procedures (Trocars) to the highest risk category by the FDA in 2016, why do you think these instruments were reclassified but the actual procedures undertaken using these instruments were not reclassified to reflect the same risk?

A. Excellent question which ought to be answered by the FDA or the Urogynaecological Society!

Q. There is not a great deal of understanding about what actually goes into a mesh implant, is it true that the plastic resin properties can differ from batch to batch?  

A. Only the companies which manufacture the polypropylene can answer that question. It is very likely that batches differ, but is it to the extent of affecting the physiology or function of the mesh? I doubt it since the largest proportion of ingredient will be the polypropylene. If this question becomes crucial it is a question for a chemist and expert in PP.

Q. Tell us a bit more about your blog, why did you feel the need to start this and how is it going?

A. I started because the extant literature is not transparent nor has it been reliably trustworthy. The Journal of the American College of Surgeons has published two articles in the last year pointing out discrepancies and discordances in hernia author’s publications. The Europeans (unlike the US and Canada) do not have to declare any conflicts of interest nor the amount of moneys received from the industry and therefore are not accountable. Difficult to check. Feel free to consult the blog. https://thehernialetter.org/