Good evening everybody and welcome to tonight's webinar. My name is Bruce Stevenson and I have the pleasure of chairing tonight's webinar. Tonight's webinar is a, sponsored webinar.

Expaniderm are our sponsors tonight and we have the head of the veterinary technical division, Chloe Booth with us. She will be doing a short presentation later on before we get to all the questions. Little bit of housekeeping from my side.

For those of you that are new to the webinar vets, welcome. If you have any questions. For our presenter tonight.

Simply hover your cursor over your screen. You will see a little black control bar. Normally at the bottom pops up and there's a little Q&A box there.

Click on that, type in your questions. They'll come through to me and we'll hold those over until the end of the presentation where our presenter has kindly agreed to allow us to answer as many questions as we've got time to get through. So that's enough from me for housekeeping tonight.

Our speaker tonight, and I, and I'm, and Guillome, I hope I get this right. Guillaume Chenoi is a French born veterinarian who received his doctorate in veterinary medicine diploma at the Veterinary School of Toulouse in 1998. He then undertook further specialist training in small animal surgery, both an internship and a residency and then completed a PhD in cardiovascular physiology.

He's a European, American, and Royal College recognised specialist in small animal surgery. And he has held academic positions both in France, the UK and the USA. Guillaume holds an academic position of senior lecturer in veterinary surgery at the Bristol Veterinary School since 2011 as a soft tissue surgeon, an educator and a researcher.

He is also a senior clinician in soft tissue surgery services of Langford Vet Referral Hospital. He is interested in all aspects of soft tissue surgery, but has a clinical and research interest in cardiothoracic surgery. And he's also attracted by several aspects related to reconstructive surgery and regenerative medicine.

So who better to talk to us tonight? Guillaume, welcome to the webinar vet and it's over to you. Thank you very much, Peter, for this kind introduction.

Good evening, everyone. It's my pleasure to be presenting this webinar on tissue expansion in veterinary patients. So during this seminar, we will basically review and discuss the physiology of tissue expansion, the mechanisms that are underpinning skin expansion.

We will also list the techniques available to perform skin expansion. There will be a fairly extensive session on cases that, have been done in, first opinion practise, where, tissue expansion has been useful in the management of the skin defect, that, has been the, The reason for the placement of the expanders in the first place. And we'll see how skin expansion can potentially, for those of you that are, have not done it yet, can become potentially a new arrow in, your quiver in your arsenal to, tackle these challenging, conditions.

So probably first of all, it's important to realise that tissue expansion and skin in particular is a natural process that is found in many physiological conditions. And therefore, when we're are asking the skin to extend, we are essentially replicating a natural process. And it's also important to realise that when we're talking about skin expansion, we are not exactly talking about the same thing as the skin stretching.

There are two slightly different, things, and all the skin stretching is. Something that's, can be used to temporarily relieve the, the tension on the skin. You have on these image, a view of a, of a, a, a partial reconstruction that has been, where, where, velcros have been used to stretch the skin and relieve part of the tension.

This is not the exact same mechanism as skin expansion. And this relates actually to two different notions, which are the notion of mechanical creep and the notion of biological creep. And these are two different notions.

So the mechanical creep is essentially What we, are encountering when, we do skin stretching, and this is the biomechanical property of the skin, allowing further extension of the skin beyond the limits of its inherent extensibility. In mechanical creep, the collagen fibres will align over time. There will be displacement of interstitial fluid surrounding the collagen fibres, and essentially the the tissue, the skin, the cells will extend.

With the biological creep, which is the process that we are actually using to form new skin in the, the process of skin extension, we are seeing a progressive increase in skin surface, that occurs, when that skin is slowly expanded. And therefore what you see on this image, here are if I point it with the arrow, this is the what's called the reference configuration with the normal resting number of cells on the epidermis and dermis, and with the loaded configuration that you see here on that image. The cells will start extending, and if at that stage the, the pressure is released, then, the, the, the skin will essentially regain its normal length.

If the growth is continued or if the, if the, the, the, the load is maintained, then the short very soon after the, the load is is main. Contain you will see, you will start seeing some divisions of the cells and therefore the cells will start growing instead of just stretching. And then when the, when you're in the unload configuration, then that multiplication of cells will remain and therefore, the number of cells per unit of measurement will actually be increased.

And therefore skin expansion can be considered time-tested and proved. Proven relatively simple to generate tissue and reconstruct defect because that skin is actually skin and and and subcutaneous tissue will be stretched over the tissue expander. And one of the main advantages of this technique, and we'll discuss the advantages later on, is that the technique provides skin and soft tissue that have the same colour, the same textures, the adjoining skin.

Where that expanded tissue is actually needed. So as we will see in all the examples that we will, mention, the expanders are placed relatively close to the area of interest, therefore, basically, multiplying the, the amount of skin available very close to the area of interest. And the physiology of, of, tissue expansion, as I said, relies mostly on this, initial resting cellular tension that we see in the skin, which is more or less due to the collagen fibres and their, organisation, during, rest or or at rest.

And if the stretched tissue, or if the tissue is stretched, during a, a process of expansion, initially, as I said, these, these cells will start, becoming longer. The, the collagen fibres will realign, the elastin fibres will realign, but at that stage, nothing will happen. To the cells, itself in terms of division.

It's only when the, the tension is maintained, for a certain period of time that these cells will start divining up, basically, extending to a growth that will restore the resting tension. And if we want to go a bit more specifically into the, sort of more cellular mechanism, we can recognise that this mechanical stimulation, which happens at the, the level of the cell membrane will involve several key. Factors that will be both at the level of the membrane with mechanical receptors such as ion channels or receptors that will then activate secondary messengers such as the cyclic AMP or will also activate some key, kinase such as the protein, protein K, or protein C kinase, and the end results of these mechanical stimulation will be the, The stimulation of of kinase that will induce a proliferation within the nucleus and therefore some degree of mitosis of these cells, and that's how the cells will transform from a stage of being stretched to a stage of dividing.

So the key points related to skin expansion are that the increased area of skin that will be generated by skin expansion comes from normal skin that is recruited from adjacent areas and also new skin generated by increased mitosis. It's really important to realise that again in the process of skin expansion, we're not just talking about stretching the skin, we're talking about multiplying these cells. There's also invariably an increase in epidermal thickness and decrease in thermal thickness during the process of expansion, and it's just something that has been recognised with any type of expansion.

Within 4 to 6 weeks following expansion, this epidermal thickness will generally return to an initial level, however, some, increase in thickness will persist for many months. And if we look at the astrology of the expanded skin, we can see that the expanded skin, has a very thick keratin layer and, in some areas, a very thick epidermis with, layers contained within the dermal layer that will be, and, and, hair follicles that will. Be contained in the dermal layer that are very consistent with the normal skin.

So the expanded skin is essentially a new generated skin that will have the same property as the skin that is missing. And this is, absolutely, . Unique to the the process of expanded skin.

No other process of skin reconstruction will allow a skin similar to the, the, the skin of, of origin to be replicated. One also quite important feature of this expanded skin is the increase in vascularization. And as we will see this, this property of the, the expanded tissue can also be used to the advantage of the surgeon, in other instances than necessarily using, .

Local skin for local repair. So, basically, the, the skin that's expanded, as you can see on the image on the right, these are extracted from a relatively old paper from the 1980 the late 1980s. Which is basically looked at the angiogram or performed angiogram of flaps of skin that were harvested, and comparing these, the vascularization of skin under which an expander was placed as opposed to control.

So the one on the top, at the top is. Is the, the skin that has been expanded as opposed to the, the skin, at the bottom, which is the control, flap. So you can clearly see on this image the difference in the vascularization and the fact that the elevate the flap that's been elevated, from an expanded, skin is, is highly vascularized compared to a control.

And this increase in vascularization come from basically neo angiogenesis that is due to the initial ischemia of the expanded tissue. One thing that I didn't mention when I talked about the physiology of, of the expansion is that this initial phase of stretching is also potentially associated with some minor ischemia of the, of the skin. But very quickly, if this expansion is controlled, then that ischemia will generate new vessels in response to it.

And therefore, at the cellular level, most of these cells will express. Such as DGF, which is the vascular growth factor. So very clearly these cells which are submitted to some relative hypoxia will respond to that relative hypoxia by generating more vessels.

And the interesting clinical application of this is that flaps that are elevated from Expanded tissues have significantly greater survival areas than acutely raised and delayed flaps. So for those of you that are, considering using, flaps in their practise, be aware that if you're actually expanding the skin of that flap, and I'm thinking of, actually. Patent flap, for example, if you're expanding the skin before you're actually using these flaps, you are more likely to have a more robust flap that will survive at a greater depth than a normal actual pattern flap, which is, I think, quite a remarkable property of these expanded tissue.

So, of course, as you can imagine, this whole concept of skin expansions started with some critical needs in human surgery. And this is one of the first, I believe, probably the first description of a, of a skin expansion. This was done to replace a missing port.

Of an ear in a patient and you can see on the left the patient before skin expansion in the middle during skin expansion and at the end, you can see the final result with the reconstruction of the dorsal part of the pinna with some expanded skin. So quite a remarkable result. This was published by By Doctor Newman in the 1950s.

And Doctor Newman is actually credited for having, reported the first, example of skin, expansion. Fortunately, Doctor Newman, died in the, the early 1970s before skin expansion really took off. And in small animals, we do have also a fair share of issues that we have to deal with, whether they are related to defects in the extremities, and we will talk a lot during this seminar in the the case series.

We'll talk a lot about the The benefit of using skin expansion for distal extremities, but there's also other challenges in areas of high motion or with large, skin defects. So we have a wide array of, of challenging continuous reconstructions that can potentially be tackled by using skin expansion. So what sort of expanders do we have available and what are the benefits or pros and cons of each of them?

So very simply put, there are 3 types of skin expander or tissue expander in general. Expaners attached to a distal port, and this is what you see on the image here at the bottom. These are the sort of more simple type of skin expander.

I will mention a couple of studies done in specifically in dogs where these expanders have been used mostly in the, in an experimental setting. There's very few, if no reports of using those in a clinical setting in dogs apart from very anecdotical, case reports. So these, expanders with this report will be The place that needs to be expanded will be attached to port, and the port will be used to gradually inflate the expander with saline or with other type of fluid that will then generate the continuous tension on the skin that is responsible for the process of multiplication that we discussed before.

And then you have expenders with integrated ports. This is what you see on this image where the port is actually within the expander, and the same process will apply where the expander needs to be gradually inflated by using a syringe and special needle in order to deliver some saline within the the expander. And then we have the self-inflating expaners which are in this image you can see two different configurations, the non-expanded and the expanded.

So these self-inflating expanders, as the name implies, will not necessitate any sort of physical manipulation of the. The expander and will not necessitate any gradual increase, of, or gradual manipulation of these expanders to put fluid in them. They will self-inflate over a certain period of time, therefore making them potentially more applicable to procedures that are done in companion animals.

One thing that is also very common and almost invariably found in expanded skin is the formation of a capsule. And that capsule is actually, or can actually be used to the advantage of the surgeon. This is a dense fibrous capsule that is forming around the implant.

And usually these are data that I Extracted from human studies, it capsule is usually thickest at the two months post expansion. As we will see in a moment, this is not the type of, or the amounts of time of expansion that we are using in companion animals, but in humans where they tend to use them for long, a longer period of time, they, they can go up to several months of expansion. Then there's progressive colonisation of the of that capsule with well organised bundles that will develop over 3 months.

And then that capsule will essentially resolve after the prosthesis or the implant has been removed with very little clinical or histological evidence that it remains over time. So this is a temporary process. The one thing that can be used to the advantage of the surgeon is that it's, this capsule is highly vascular.

And therefore, that, explains in part the high vascularization of these flabs because this capsule is bringing quite a lot of, vessels. The capsule itself, so that capsule can be harvested as a local flap, because of this vascularization in veterinary patients, as you can see on this image, you can see that the, the capsule is here. This is usually still attached to the skin and not used as a local flap, but it's contained within the, the skin flap.

So expanders can come in different shape, and the different shapes mean different results and different results in things like absolute area of gain, different results in terms of, Expand the volume or or different results in terms of residual stress. So as you can see, there are different, the different shapes that have been looked at, mostly in human, studies are oval shapes or, Shapes or crescent shapes or other shapes like that where the square or rectangular, where these absolute area of gain has been studied and the circular being in these studies, the one that's leading to the highest absolute area of gain. So going back to the veterinary literature and the, and what the, the sort of, sort of information that we have available up until now in terms of use of expander in dogs, mostly relates to experimental studies, as I said, there's very few.

Examples of, of case reports of using, of using these expenders. So, of interest, there are two, main studies. First one that I'm presenting here, which has been published in 1993 in veterinary surgery.

By Gary Sputnik and, and our, looking at the expansion of skin in areas of, the crus and area of the antebrachum. They've found similar findings as the one that we've described, previously, which is that thick and highly vascular flabs. Interestingly, in this experimental study, they haven't tested these flabs.

But the cruise region was better than the expansion over the antebraium. They did find small areas of necrosis or seroma that were found even every now and then on these flaps, but rough the flaps found to be quite robust and definitely able to be used as advancement or rotational flaps. Another study that was published a year later also in veterinary surgery by Kelleret Al has actually looked more closely at the type of vascularization and the histology of these flabs.

Again, it's an experimental study in dogs and in this study, they've the pattern that we've described before with a highly vascularized expanded skin and also some degree of inflammation with the presence of neutrophils within the, the, the, the thickness of the, of the skin. So, so far, all the data that were available were experimental studies. And as I will show in a, in a second, we, we have, with, some skin expanders conducted some of the first, clinical studies looking at, cases that have had, skin expander placed for clinical reasons.

So, These expanders, when they are placed in order to maximise the, expanded expansion of the skin. And maximise the positive results, they have to be implanted in a relatively consistent way. And throughout the cases and with experience, we, the, the technique of surgical implantation has been refined and I think it's fair to say now that there are some pretty robust guidelines in how these, these expanders should be placed in order to maximise their effect.

So if you take for example this image where the proximal part of the limb, let's take the limb as an example because that's a very common example of where these flaps can be used. So this is the proximal aspect of the limb, this is the distal aspect of the limb, and this is the defect that needs to be covered. So the major blood supply comes from the proximal aspect of the limb with a bit of blood supply coming from distal and also from the side.

In order to maximise the, the chance of having a robust flap that you're going to use to complete your defect or, or fill in your defect, the incision in order to place the implants has to be made away from the main blood supply. So that dotted line A is an example of where that skin, that initial incision can be placed. And then the expanders can be placed within the pocket that's created between the incision and the skin adjacent to the defect.

The other option, if this one is not possible, is to create an incision, in the proximal aspect, but, being parallel to the long axis of the, of the leg in order to, minimise disruption of the blood supply and use that remote incision. To, place, the skin expander always very close to the the defect as we said before, but through a remote incision. And in any case, and this is here, talking about almost 100 cases that have gone through that planning of of of placing expenders and how they should be placed.

The planning has to be done very carefully, and whenever there's, whenever a case is, needs to have expanders placed, one of the first thing that needs to be thought of is where, where would it be best to recruit the skin from. And as you can see on this image, it's not uncommon to have a play with the image and place these expenders and and and try and see how these expenders will be best fitted in in order. To bring in the skin in the defects.

So, for example, over the elbow region here or for a mass over the carpal pad. So there's all sorts of careful planning that needs to be thought of when, you're deciding to place these, these expander. And again, the idea here is to maximise the chance of having full expansion of the skin where you need it in order to have the best, results possible.

And then once that planning's been done, then the surgical implantation is usually something that is really very straightforward because all the work has already been done in terms of planning. So in that case, this is the planning before the, the expanders are placed, this is the, the mass that needs to. Receptor is the lick granuloma.

This is the proposed incision to place the expander and these dotted lines are the proposed flaps when the skin is expanded. This is the expander being placed and this is the immediate result before expansion starts. So in some surgical key points to remember when these skin expanders are placed, are that we tend to not use them over traumatised skin or skin previously exposed to radiation.

They're not to be used in infected wounds. Scar in general will affect the blood supply to the surrounding skin, so one need to be mindful about not using them too close to scars. Expanders should not be handled with any instruments, and it is true for any expenders, but even more so for the self-inflating expenders, as Cloe will explain to you later on tonight, these expenders are made with such technology that if they leak, then the whole process of expansion can't happen.

The pocket created should not be oversized, so there is, and we're extremely strict about this rule, we need to be very mindful that the the pocket that's created match the size of the of the expander. We don't want them too tight, but we don't want them to be able to move within the pocket. And the implantation incision should be as close as possible to the area of expansion and should be closed without any tension.

And then, of course, this is also, it's also been a learning curve in the first few cases that have been done. The expanding skin needs to be closely monitored, in the first, few days and within the whole, during the whole phase of expansion. So now that we've talked extensively about how skin expands, why it expands, the mechanisms, how these expanders should be placed, let's have a quick look at the indications and then we'll, look at a few examples of skin expansion.

So the indications are based on the location and surely distal limb presents a very unique set of indication because in this location, very little skin is available and the existing method of, of defect closure can be potentially fraught with complications. It also works with proximal limb. It works with defects on the head, and the axillary region, trunk, tail, at the base, down to, the third, of the tail.

And it also works for different types. Of pathology, there's examples of, of treating mast cell tumours or other types of neoplasia, non-healing wound, or benign growth. All of those can represent indication of, skin expander placement.

And let's talk about skin expansion or tissue expansion in the face of of the presence of a tumour. There's an interesting paper that was published a long time ago, 1991 in a human journal, looking at the the the growth of tumours under expanded skin. So on the left of the image here, you can see the study design and setup.

It was a study done on rats where rats were actually injected with some tumour cells and were, were supposed to, have the tumour growing over their sort of, middle middle third to bottom of the. The rump here, ramp area where, that tumour was supposed to grow. In, the sham animals, they've just received an, an incision with nothing placed, here under the skin.

And some of the, of the animals, received the placement of a, of a non-ex tissue expander. And some of them had, the Tissue expander, expanded over several days. And what is remarkable with these, with, this study is to show that actually on the ones that had the expanded skin, the, the tumour growth was actually reduced significantly compared to the control or the sham procedure.

And you can see here, basically, over the course. Of the different, the, the, the course of the expansion, the actual growth. Of the tumour, which was markedly reduced in the expanded group compared to the control and sham group.

And in the, and, and similarly to the for the weight of these tumour, this weight was significantly reduced in the expanded group compared to control and sham. And the author, speculate that the reason why, this happened is essentially because the, expanded skin is taking away the blood supply and therefore, cut down the blood supply to the tumour. So there are some evidence that actually expanding skin, around tumorous area is not going to necessarily lead to, a complete, overgrowth of the tumour or the.

An overgrowth of residual neoplastic disease, but actually might be the contrary. Of course, this is a rat study. This has not been proven clinically, but this is this is interesting to use in order to have an informed idea of what's happening with tissue expansion in the presence of tumour.

So in kind of summary of the pros and cons of tissue expansion, we could say that tissue expansion, usually, provides excellent tissue match with limited donut cyte morbidity. Large wounds can potentially be reconstructed. Avoid scar associated with remote flaps.

We highlighted the good vascular vascularity of the flap, which is a very unique and very important feature and essentially, something that could be discussed later on, the cost-effectiveness of tissue expansion versus bandaging of the, of the wound. There obviously are cons as well, such as the prolonged process between 2 and 4 weeks of expansion before the skin can actually be used, the multi-stage procedure, there's a need for ops in order to provide the, the final outcome, one to place the expander and the other one to remove expander and, and perform the reconstruction, and then the potential abnormal body control during expansion. So, and that's the second part now of that, of that that webinar, I would like to present typically quickly because there are most of these examples are available on the Oxte website.

So if you want to have a look at those, they are available. I'd like to present, . The, outcome of the studies that we have conducted on, skin, expander, self-inflating skin expenders, and, report the outcome of our initial 12 cases, which was published, earlier on this year in, in Jo Moal practise.

That paper was essentially a proof of concept where we've looked at the initial 12 cases, and report the, initial learning curve. And it was a learning curve for the surgeons, a learning curve for us as well as, people that were giving advices on how these expenders should be placed. This study only includes clinical cases that, in which self-inflating expenders have been used.

And one of the Most important results that we found was that the, these skin expanders were working remarkably well in lesions proximal to the tarsus, or culpus and distal to the elbow, and, stifled. And just to show you one of our most remarkable examples, this is a soft tissue sarcoma, in the situated right between the elbow here and the carpus here in a dog. These are, pictures, from Marco DiLorenzi, who was the, the, the, the first author in the paper that, I've mentioned.

In, I will talk you through the different steps of the management of this case. So, Initially, the margins were measured around these, this tumour. So the tumour is highlighted, here, with a solid, mark, and then the dotted line are showing the, margin around that soft tissue sarcoma that we're going to be taken.

It's, it's very obvious when you look at this image that, primary reconstruction was not going to be. You need to go ahead and place a, a skin expander. So this is the subcutaneous dissection initially.

So as you can see, the incision is made very close to the margin. And then the device was placed, so this is the device being placed in that pocket. Again, the pocket is made in such a way that the device will just fit in.

And then the skin is sutured and some retaining sutures are placed, and the purpose of these sutures are that are to tackle the underlying tissue and the skin around the expanders, making sure that the expanders have no room to move around. This is the post implantation, immediately post implantation, so we can clearly see these two circles, which are the two unexpanded, self-inflating expander. This is 2 days post-implantation, so the expanders have started to expand and therefore you see a bit of contour of the skin that is slightly modified.

This is 8 days post implantation, further expansion of the skin, again, with a good healing of the initial incision, so very little morbidity on the surgical site. This is 14 days post-implantation, which is nowadays the, the maximum, implantation and expansion of these expander. And this is the removal of the device.

So the same incision. That was made in the first surgery is used again to to expand these expanders. The tumour is removed with the margin that were initially made during the original description.

And then an advancement flap is created using the expanded skin. So as you can see on this image, the expenders have been removed. This is the expanded skin, so the additional skin that's been created by the skin expenders, and this is used, .

To raise an advancement flap. This is the image I showed you previously with the capsule, that you can see here. So highly vascularized, flap, very robust, very easy to use, additional skin that can be used as an, as an advancement flap.

The advancement flap is slightly by. But it's OK cause that actually fits very well with the reconstruction. And this is 2 weeks post.

Construct and Complete closure, no tension, and a functional and cosmetic, which is very acceptable and probably better than any other type of repair that could have been done in, in this area because if you think about the alternatives such as a a skin. Graft or a potential, actual pattern flap, it would probably result in, a skin that would have been slightly different than the local skin. So, again, one of the unique features of these flaps is to provide a skin that is, that exactly matches the defect.

One thing that I'd like to, mention as well that we found quite interesting with these expander is the fact that after they're, they're placed, these, some of these wounds have had a tendency to decrease in size. So you can see on the left-hand side, the, the wound that I've showed you previously before. Expander implantation.

So you see a quite large wound on the elbow, and this is the same wound in the same location, but after expansion of multiple expanders that have been placed on either side, and you can see even if there's, there's no actual objective measurement that the The wounds actually fairly reduced. So we think that this process is actually related to the high vascularization of the skin that happens following expansion, and this can be used to the advantage of the surgeon by reducing the amount of defect that needs to be covered by the skin. One thing, if we are looking, and this is what we've done, looking critically at these initial cases, we need to also look at the fact that, these expander initially did not give us very good results, in the defects that were below the carpus and tarsus.

So we think that some of these initial complications are due, were due to placements of the expenders, shape of the expander, also the post-operative care. We learned a lot from the initial cases about how these, post-operative care should be conducted, the rate of expansion, whether this expansion was happily or too slowly and therefore leading to poor results, and Global understanding of the vascularization of these expanded skin. All of this has now been, basically troubleshoot and, is, now working much better.

But as I said, we've been very thorough in our initial description of the cases and we've accepted, a learning curve and showed very openly this learning curve in these initial 12 cases. But now we have, I would consider much better results, a much higher number of cases that have been done and therefore much more experience in how these, skin expansions should be dealt with altogether. And these that we have gathered recently over about 50 cases.

This, the whole 50 cases are not presented here. Some of them have been lost to follow up or we're still gathering information on them. But what is really interesting, and these are part of our initial results, these are the number of dogs based on the different anatomical location where the expenders have been based.

So you can see here on this image the different location, A being, proximal to the elbow or proximal to the stifle, B being between stifle and hock, or between elbow and carpus, C, D and E and F, being respectively, . Stifle hawk, and then below, the, below the carpus and below the hog, then at the level of the trunk, and at the level of the face, or level of the tail. And you can see that the amount of primary closure.

Is really good in all groups and more interestingly, in that group where we initially had quite a lot of bad experience, distal to the campus and distal to the tasks, we're now reaching an over 90% success rate in primary closure. The number of complications has also dropped. There's only very few complications that have been recognised in these different cases.

I haven't put any percentages here, but you can see the numbers and they speak for themselves. Very few complications, minor and major complications are, are very rarely encountered nowadays with these, expander. So I'll probably go quite quickly through these cases because I'd like to give some time for discussion and for Chloe to present some of the, the, the information about the expanded so these cases, such as the muscle tumour on the nose here are available.

On the website, the OE website. So you can see here, the expand the expansion of the skin right by, the nose at the level where the, the masal tumour is right next to it. This is 3 days post implantation.

This is 14 days post-implantation, and you can see the the large expansion of the skin on either side of the nose where the skin expenders have been used. And this is the mass removal. That tumour was removed with a narrow margin, but that was part of the original plan.

The large margin was not was not feasible in that instance. And this is the expander being removed and the flap being created. And this is post reconstruction, so a fairly good cosmetic result and a complete closure of the, of the defect.

Very few other techniques would have allowed the, the surgeon to close that defect primarily. Another case here of L I Groma again case that are available on the Ostes website. So this is post implantation.

Again, these are strategically placed in order to recruit the the the skin around the, the, the, the defect that will be created. This is 14 days post-implantation. Again, you can see that there's very little changes in the skin apart from the expansion, no necrosis or any problem.

It is very well tolerated, and the animals will let the, let that expansion process happen very seemingly. This is a defect made before reconstruction, and these extra skin will allow the surgeon to reconstruct the defect. This is the final result.

You can see here that the incision is actually placed away from the bony pyiminence, therefore minimising the risk of having any dehesence of the wound, and it's obviously under no tension at all. And this is finally a distal lick granuloma. So again, these very challenging region, distal to the carpus or distal to the tarsus, will be amenable to treatment with skin expansion.

And just to conclude, tissue expansion is just, it's not just about the skin. There are also other instances where these have been used. There are some initial experience that have been done with palatine mucop pericium expansion in sheep.

This is an excellent model for crossbite lesions in, children, and we're hoping that in dogs, this can also be used to treat challenging cleft palates. Expansion of mucosa in horses. This is a, a cleft at at the vestibular volva junction in a mare that's been successfully treated using skin expansion.

And this is a snake here, but I'm sure Chloe will be happy to tell you more about this snake and these expanded skin here on the snake. So in conclusion of this seminar, we've we reviewed skin expansion and we need to be mindful that skin expansion is a natural process and therefore, we are basically replicating that natural process with skin expander. Skin expansion in companion animals can be used successfully to treat defects in various anatomical areas.

It's not just related to distal extremity, even though this is probably one of the main advantages of skin expansion, but it can also be used in other, anatomical regions. Self-inflating expanders are probably more suited for companion animals. They are at least the only ones that have been reported clinically, and they seem to be tolerated very well by companion animals, and at least they, you don't have to worry about putting fluid in a pocket and poking these these expanders every day to inflate.

Expander can also achieve primary closure and help to achieve suitable margins in cases of tumours and indications are looked at beyond skin reconstruction, even though at the moment, this is the majority of the application, but other avenues are being researched at the moment. So that's it for me. I've been slightly more than maybe about 50 minutes, 51 minutes.

So thank you very much for your attention. I'm very happy to, leave the, discussion now to, for Chloe to present and, and open the floor to questions. Thank you very much.

Guillaume, thank you so much for that. That was absolutely fantastic. We have loads of questions coming in.

Folks, as I said to you in the beginning, what we are going to do now is we are going to just change screens. Chloe is going to give us a, a short presentation. On the expanders and that.

And then we will come back again to Guillaume and to questions. And remember, questions can be either to Guillaume about the surgery and that, and I have loads of those already. But if you've got any questions for Chloe, she can also, tell us.

What's what's happening. So Chloe, it's over to you for the expanders. Great, thank you very much.

So, good evening, everyone, and thank you very much for, for joining this webinar. I hope you've enjoyed it. My name's obviously Chloe.

I'm head of the veterinary technical division at Oxtech. We are the company that actually make Expanidderm. So I'm just gonna tell you a little bit about them.

So Expanyerm are a new generation of self-inflating tissue expander. They're made with a hydrogel core and a medical grade silicon coating, and I know that there have been a few questions about their construction, but it's essentially the unique construction of these 20 my apologies. The unique construction of these two materials that allow the expanders to have a controlled increase in height only.

Now this is quite important because it's different from traditional balloon expanders. Most importantly, in that they're suitable for use in more anatomical areas than balloon expanders are, just as Guillaume has showed you, but also, in that they create skin only where you need it. I saw that there were a few questions as well, asking how they work, and they do work by absorbing tissue fluid, and I know there was a question about that.

So essentially they're placed subcutaneously. They expand over a 14 day period by absorbing tissue fluid. And that expanded tissue that's then created can be used for a number for a number of indications in multiple different species, again, as Guillaume showed you, and I saw that there was a question about a cat.

They can be used in cats and the best thing to do would be to email me any questions you have about cats. So moving on, there are benefits of expandedderm at all the different stages where they're used. First of all, at implantation, you get flexibility of size and position, and this results in a bespoke expansion that fits each individual case.

Because you can use 1234, as many expanders as you need, it means you get the exact expansion that you want. It also eliminates the need to manage secondary wounds, as we've already discussed. At the expansion stage, the self-inflation means that there's no interference needed between implanting the expanders and reconstruction.

As I've already explained, they increase in height only. The benefit of this is that they, they don't encroach on any margins that you might have, and you get a much better level of expansion. You get fewer clinic visits, and, oh, my apologies, and this is obviously more convenient for clients, less stressful for the animals.

There were, I also saw a few questions about how well they're tolerated. The answer is very, very well. What you tend to notice is that in the 1st 24 to 48 hours, there may be some discomfort.

Now that's because of the pocket that's been created to actually insert the expanders, not because of the expanders themselves. Once this initial sort of period of of discomfort has, has lapsed, and as I say, that's usually about 24 to 48 hours, the, the actual expansion process is not painful at all, and we've done many, many cases and we see no lameness and no discomfort. That dog that you saw with the expanders in his face was eating and drinking normally for the entire expansion process.

And then at reconstruction, obviously, having the extra skin allows closure of wounds and surgical sites that would otherwise not have been possible. And this obviously means that you're much less likely to have any wound breakdown due to excessive tension on your repair, and it also gives you the opportunity to take larger lateral margins that you might have done, giving you the best chance of curative surgical treatment. So moving on to how they actually work, so there are 3 different phases of the expansion profile of these self-inflating expanders.

This initial section here is the 1st 2 to 4 days where you won't see any expansion. The reason being, if I just play that again for you, is that. If the, it allows the incision or wound to heal slightly before the expanders start to expand.

After this initial 2 to 4 days, you get a slow, constant rate of expansion up to 14 days, and at 14 days they are an approximately 95% expanded. You can leave them in for longer than 14 days depending on your anatomical area. Anything distal to the carpus or the task must be removed at 14 days.

But any other areas, you can potentially leave them longer than that if you wanted a little bit more skin, but we find that 14 days is optimal. In terms of the sizes that we have available, there are 3 different sizes that we use most frequently. This line here, is an expander which is of 27 millimetres diameter.

This is our largest expander. It starts at 9 millimetres in height and will expand up to 25 millimetres. We have a thinner expander, which is of the same diameter, but this will start at 5 millimetres in height and increase up to 18 millimetres.

This middle line here, these are the ones that you would use distal to the carpus and the tarsus, and you can use those in conjunction with our smallest expander, which is a slightly smaller diameter of 22 millimetres, and we'll start at a height of 4 millimetres and expand up to 12 millimetres. Now, these two expand. Here will give you approximately 1.5 centimetres of skin for each aspect that you place them.

So if you were to place some of these expanders on, on, say, for example, laterally on a mass and also medially, you would get 1.5 to 2 centimetres from each side, giving you a total of 3 to 4 centimetres of extra skin. So what do you do if you wanted to use them?

Well, the best thing to do is to take some photos of your case. Note the type of defect it is. So if it's a non-healing wound, or if it's a mass, what type of mass it might be, get some size measurements for us, as well as the exact location, and the patient's weight, and breed.

These are important for us to know what size expanders you might need. You can then email all of that information over to your regional territory manager, and if you get in contact with me on the contact details at the end, I can direct you to the right person, or if you're not in the UK, then I will, I can deal with your, your case directly. So once we've got all this information, what we do is we can advise you on the, the best size of device that you might use, also how many of them you would need and how best to place them.

And this is really important if it's your first case, because it's hard to know what sizes you might need and, and how best to place to get an optimal result. So we can really help you with this. And as the last point says here, we can give you full technical support through your first case, and that can be as much as, or as little as you need.

But what we really want is for you to, to get the best out of the expansion. So we're, we're more than happy to help in any way we can. So those, that's expanded them, and this is, these are my contact details.

So you can either email me or, or you can give me a call on either of these phone numbers. The case studies that Gha had on his presentation are all available at www.expaniderm.com as well as more information and many other case studies as well for you to have a look.

And if you've got something weird and wonderful, which I haven't spoken about, or you just want to have a chat, then please by all means do just, just give us a call and we're we're more than happy to help. Chloe, thank you very much for that information and I see that you've, you've covered a lot of the questions already, which is really, really good. We might go back and just touch on some of them because they are repeat questions coming through.

Guillaume, if I can ask you a common question that's coming through is, and, and Chloe did touch on it about the pain of implants. There's various Questions and I'm, I'm paraphrasing here, but do you use any pain control and NSAIDs or paracetamols or anything like that in these cases? Yeah, no, absolutely, that's a good question.

And this is absolutely key to the, to the management of the case overall. And yes, the answer is we use NSAIDs or we use paracetamol as needed. The whole process, as clearly said, is not more painful than you would imagine a, any sort of reconstructive surgery.

To be, so the, the process of expansion, should not be looked at at something with, as something that needs to be treated more aggressively than than any sorts of other reconstructive surgery. So, yes, NSAID, paracetamol, occasionally buprenorphine could also be used very rarely anything, above that. My experience, sorry, just to jump in, my experience of these cases has been that, often, as Guillaume says, NSAIDs, are used for, as I say, for the 1st 24, 48 hours, but it's very rare that, any ongoing pain relief, certainly for the use of expandedderm is needed, for any longer than this period.

Obviously there will be the occasional case, that has a, you know, experiences more pain for some reason than another, but the vast majority of cases don't need ongoing pain relief throughout the expansion process. That's excellent. You touched on it a little bit, Chloe, but there are a few questions that have come through.

Inevitably, yes, but what about cats? Well, as, as a cat lover myself, I can understand. So the answer in terms of cats is that, they do work in cats.

We don't have many cat cases. The reason being that we, with cats, obviously being cats are difficult in that they have obviously very different temperaments to dogs, and their lifestyle is obviously quite different as well. So, in terms of cats where it would be suitable, you would need a cat with a very specific temperament, and one where, an owner would, would need to be willing to keep the cat indoors for the entirety of the expansion process and have it wear a busterolar.

So, I mean, the short answer is they work very well in cats. They work as well in cats as they do in dogs. It's just more a case of logistics than it is about the actual, technicalities of using them.

In other words, nobody's told the cats that it's OK. Exactly, exactly. I think no, no, I was, I was just gonna say that the that the there are, there have been sort of cases that we have shared with Chloe like the the collar injury in cats where we've, we've seriously thought about the about placing expander in because with the with.

The sort of more, sort of recent understanding of how these, these collar, injuries should be treated in cats. I think using expanders can be really a very nice adjunct to the, and, and help for the treatment to, enable the surgeon to reconstruct the, that fold, that axillary fold that needs to be reconstructed. So we've, we've had cases where we certainly thought about using, these expanders and cats.

Excellent. Interesting question that has just come through here and may send Chloe back to the drawing board and certainly Guillaum and give you something more to study. The question came through, what about fish?

Mm. Oh, we have you stumped now. Well, the, I mean, from, just from working from basic principles, I mean, Guillaume, correct me if I'm wrong here, my concern with a fish would be when the expanders expand, they actually, if you have a look at the picture of them, they, they start as a disc, and actually what they're doing is they are actually expanding in both directions from that disc, so both up and down.

Now what we tend to do in, in most species is that you're actually usually placing it against a bone. And obviously, as the expander increases in height, it'll take the path of least resistance. Now, that would obviously be placed against between a bone and skin, that would be to, to push the skin up.

And my concern in a fish is that you just wouldn't have, that, that, that the bone wouldn't have the strength to actually push against the expander. I don't know, I don't know what you think. Yeah, I, I, I, I would agree, but I think you have this, you have this amazing snake case that I've only basically alluded to, in the, at the end of the presentation, but I think, I think you're right, there's some instances where the pressure would would actually cause, could potentially cause some more harm than, than, than good, and I, I don't know whether the, whether fish would fall in that category or not, but, but you know, as I said, you have these, you have this amazing case with the, with the.

That I think is a bit pushed the pushed a bit the, the boundaries of how how expenders could be used. So maybe, maybe fish isn't the limits, maybe nothing is the limits of the of the skin. I suppose it's size of the expander and the weight of it because obviously can't if it's all lopsided.

I mean it'd be interesting to look at, but I'm not sure that actually I'm not sure how how clinically well it would work. Right, another question, Guillaume, you did allude to it in the one slide there. Lots of questions coming through about migration of the implants.

Yeah, well, I mean, technically migration can happen if the, if I suppose if the pocket is done in such a way that the the implant has is a bit, a bit of leeway, but, if, if you're careful with the, with the pocket that's created, and at some point initially we've used a a, a dummy expenders that. Was, that was available where you could actually, basically look at the, the size of your pocket with an expander that wasn't going to be the final expander just to judge the size of it and make sure that the, the, the expander expander would be, or the pocket would be at the right size. But I think with, with time, it's something that Or, a second nature to you, you, you're making the pocket, judging by the, the size of the expander and you're very rarely running a complication, such as making, making a huge pocket.

It's broadly something that you need to be extremely careful with, with the 1st, 1st 1 or two implantation, but then after that, you, you, you sort of realise this. The type and depth of, of a pocket that you need, you need to create, and that becomes, less of an issue. And as I showed in the, the cases done by Marco, there is also the possibility to use tacking sutures.

If you have, if you have done a pocket that's too wide or too deep, or that you think that the, the, there's some wiggle. Room for the, for the expanders. There is a possibility to use the fascia or use the sub subcuticular tissue that you have in the, within the pocket and actually tackle this back to the subcutaneous tissue in order to reform the pocket to the desired depth and, and, and size.

Obviously, at all costs avoiding the expander. Yes, definitely. Yes.

Of course. Interesting load of questions coming through in various phases and folks, I'm sorry I'm paraphrasing, but I can't read out all the questions. .

The questions all relate to atopic skin disease. And they basically are, can you use it in atopic skin disease? Will it irritate?

What about the medicines used for atopic skin disease? Things like Epaquil which blocks the jack pathways. Is that going to stop the, the multiplication of the skin and rather turn it into, you know, a stretching of the skin rather than a growth in the skin and then obviously how does atopica as a drug interfere with all this?

Well, that's a very, that's a very good question, and, and I, I, I don't have a, a straight answer to that question not having been facing the challenge of doing skin expansion on an atopic skin myself. So I don't know if Chloe has any, any results or any case that she's supervised where this has been a, this has been, a question raised, but Personally, I don't have any experience. I think the, the, the point about the, the suppression of the, of the jack pathway is a very, very relevant point.

And it's probably not been looked at, in terms of how, how this will impact the, the, the potential mitosis of the skin. But this, I think if I had, if, if two more I had a, a case like that in, in practise, I would believe. Warn the owner in, in a way that, I would probably not, completely withdraw an expansion, as a potential option, but I will just make sure that the, that the owner is aware that, some of the, some of the pathways or especially some of the, of ways the, the, the skin will expand my.

Be slightly changed by it. But again, I'm not aware of any studies that have specifically looked at the, the, the, the role or, or the the deterious effect of apoquela on skin multiplication or anything like that. Do you know, do you have any, any, anything, Chloe, on that?

So no, I agree with you in terms of the sort of, the, the pathways and the actual physiology of how the drug would actually affect, what the skin is doing. I also, I don't necessarily. Have an answer to that.

I have had one case, where I had a dog who had, fairly severe skin disease, who wasn't on Aquil but was on steroids. And they actually did stop the steroids a few days before the surgery, with the inevitable result that the skin became considerably worse during the expansion process. And then that obviously had.

Implications in terms of how the skin ultimately heals, so I think it is quite a difficult one, in that, you know, there's a, there's a balance between maintaining, you know, The the animal's comfort, for one, but also, maintaining skin that, that can heal nicely. So I think it's, it's something that we would probably help you with, and we'd have to address on a case by case basis. But I, I would shy away from, from sort of giving a very general answer to that, because I think it really does depend on the case, and depend on, on what you're hoping to achieve, which is, is a bit of a cop out, but I think that's probably the safest way to put it.

Excellent. Folks, just to let you know, there are a lot of questions coming through that have already been answered during the presentation. Just remind you, these sessions are all recorded and in a few days they will be up on the webinar vet website.

So you will be able to go back and re-listen to this fascinating presentation and a lot of the questions that are coming through, we're not gonna have time for, but they have been answered. Chloe, next one is for you. Lots and lots of variations on this one, but essentially costs.

So the, again, the cost is probably something that's, best discussed on a case by case basis. You know, at, at Oxtex, we don't want cost to be inhibitory to you using the expanders, but it really, and, and again, it sounds like I'm being intentionally vague. It's not that, it really does depend on your case.

So again, I think the best thing to do is that if you have a case and you think that your patient could benefit from using these, then the best thing to do is please do get in touch with me and I'm, I'm more than happy to discuss that with you. OK. On a, again, paraphrasing many, many questions together.

When we're talking about being very careful to handle these expanders and not damage them and everything else, what about infection? So in terms of infection, what I would say is that we can guarantee the sterility of our product. The expanders are gamma radiated and we do intense testing on them to be to ensure that they have an extremely low bacterial burden and we have.

Very, very strict measures in place. So we can, we can absolutely guarantee the sterility of the product. They are sterile implantable devices.

Obviously, what we can't guarantee is the sterility of the surgical environment, or what happens, you know, even once, your implantation incision has been closed. I have had cases where everything's gone absolutely swimmingly, and then, for example, a buster collar has been removed and an animal's managed to lick the incision, which is obviously disastrous. So, obviously, infections can happen, and as I say, it's, it's rarely or never as a result of the expanders themselves, but usually of something that's happened around that.

Now, some infections, are minor, obviously and can be controlled with antibiotics, and other measures. There are cases where, if, if the infection is not caught in time or if it's, severe, then the best thing to do is essentially remove the expanders because as we know, having any kind of implant in an area that is infected is usually bad news. So it's something that we, as I say, we try and avoid as much as we can just through, you know, sterile technique.

But it's, it's a complication that can never be totally avoided. But as I say, if, if you're careful, it, it shouldn't generally be a problem. OK.

Interesting one here. You mentioned a buster collar coming off and a dog licking at it. There's a question about what if an animal or this one says specifically a dog eats the expander besides the physical, problem with obstruction, toxicity levels, how quickly do you need to get an X lap going?

So I would say if the dog's large enough for the expander to pass through, then that would probably be fine. Both of material. Are totally inert.

So both the hydrogel and the silicon are inert, so you wouldn't get any kind of strange foreign body reaction. Now, if it was a very small dog that had obviously swallowed a very large expander, well, first of all, that would be extraordinary. And second of all, yes, unfortunately, it would be a foreign body and probably would require an ex-lap.

But again, that's something that I would hope wouldn't ever happen. Yeah, Murphy plays a role in these cases, doesn't he? Excellent.

Folks, I'm afraid we are running out of time now and it is my absolute honour to be able to thank both Guillaume and Chloe for their time and their presentation. There are loads and loads of questions on the screen you have Chloe's details, as she has very kindly said, email her, call her, discuss the cases. I would suggest go back and watch this presentation again and then call them because a lot of the questions you're asking have already been answered.

But Chloe is there to help and guide you in all these cases. And Guillaum I'm, I'm really looking forward to seeing more published work that you are doing on these. And who knows, maybe you'll give us a fish case, a case one day.

Yes, or a, or a snail. That would be really good. Yeah.

Guillaume and Chloe, thank you so much. There are loads of messages coming through saying very informative. Thank you very much.

So everybody is, is really echoing or I'm echoing their sentiments of a great thank you for your time and everything tonight.