Hello everyone, good evening, good afternoon, good morning, wherever you are in the world. Welcome to the third joint ASPS Plaster UK webinar, which is part of the wider ASPS Global Partners webinar series. I'm Vik Sharma, the Plaster UK international representative and a trainee here in London. Tonight we've got an exciting program ahead with three very different and very interesting talks that really represent the cutting edge of plastic surgery research. After each talk, there'll be a chance to ask the speakers any burning questions you have, some brief housekeeping rules today. Please enter all your questions into the Q&A function at the bottom of the screen. I know everyone's an expert in using Zoom now, but please use the Q&A box, not the chat box or WhatsApp or anything else. And I'll ask those questions on your behalf at the end of each talk. So kicking things off, we've got the three speakers from Germany, Italy, and the UK that you can see there on your screen. And first off, we'll have Urshka Sobran, who grew up between Italy and Slovenia, did her undergrad studies at St. George's Medical School in London, and then has moved to California, where she worked as a research associate in the hand surgery department in Stanford, and then has pinged back to Aberdeen in Scotland, where she did her initial junior doctor training. She then moved to Germany, and she started plastic surgery training there. At the moment, she is a resident of the Helios Clinic, Emil von Bering in Berlin, and has a lot of research interests focusing on global surgery, microsurgery, and professional surgical dynamics. So she's going to be talking to us tonight about the surgical challenges in microsurgery in low-income settings, and she'll look at the pre-, intra-, and post-op challenges that will encompass her own research experience, and any relevant literature will also be presented. Okay, Urshka, take it away. Thank you so much, Vic, for the nice presentation. So let me just start sharing with you. All right. So as Vic mentioned, one of my favorite topics in surgical research is global surgery, as well as microsurgery. So I thought that for today's talk, I'd kind of give you a little overview about how microsurgery fits within global surgery, and then what is actually the current state of the practice of microsurgery in the low-income setting, and what are the main challenges. So just to give you a quick introduction, global surgery is part of public health and global health, and I think now about a decade ago, the Lancet created a commission that basically found that about one-third of the global burden of disease is caused by conditions that can be treated surgically. And of these, and on top of that, about two-thirds of the world's population don't have access to surgical care. So how does actually microsurgery fit within global surgery? A lot of the time when one discusses global health and global surgery, we tend to forget about microsurgery or not mention it, because it's kind of seen a bit of as an extra and not something that is necessary, but something that is rather nice to have. I think we can all disagree with that, but just to kind of discuss that or disprove that further, we all know that microsurgery really improves the patient's quality of life. One of the main ways to measure the impact that disease has and the burden of disease is by DALYs. If you're not familiar with this, this is a measure that is basically created by two different measures. The first part is years of healthy life lost due to early death caused by a disease. And the other part, the one that's important in microsurgery, is the years lived with a disability caused due to this disease. And I think microsurgery really kind of lowers the DALYs of a condition due to the improvement in quality of life. And so on top of that, about 66% of all DALYs caused by diseases that can be treated by surgery are related to reconstructive surgery. And just some further examples, we're talking about breast cancer, about road traffic accidents, which cause some of the greatest disabilities, greatest number of disabilities on the planet, and we forget, but actually also some infectious diseases such as lymphatic filariasis can be treated with microsurgery. Now I'd like to give you a little bit of an overview of what's actually happening with microsurgery in the low-income countries. I'll be doing this by using a paper that we published last year. It's a systematic review that looks at papers that talk about outcomes in microsurgery on surgical missions. And funnily enough, about the same time as we published our paper, Bandaytel published a similar paper also in JPRESS about the outcomes of microsurgery in Africa. So I'll be mainly comparing these two papers. So in both cases, there wasn't that many studies included. We had seven studies from the countries that you can see on the map, whereas Bandaytel had nine studies. And I think it's worth mentioning that this tends to be, this just showcases the paucity of data on outcomes of microsurgery in the low-income settings, because usually when we talk about global surgery or just surgery in general in a resource-poor environment, the research tends to be more about the economic burden or the type of diseases, organization of surgical missions, and that kind of thing, but not actually about outcomes. And I think that really needs to change. Anyhow, we found that the majority of our free flaps were done due to infection, cancer, trauma, or burns. And the main recipient site by far was head and neck. And this is actually similar in Bandaytel's study. They found that about one third of all of their free flaps were used for head and neck cancer reconstruction. And I find really cool, but 2% of the free flaps were used for breast reconstruction. The main flaps used were the radial forearm flap, the ALT, and the free fibula flap, as well as the parascapular flap. And this was reflected in Bandaytel's study, as well as a study that we performed in Ethiopia that I'll talk about in a little bit. So, in terms of outcomes, there was actually a big difference between the performances found by us and those found by Bandaytel. I think it's worth mentioning that Bandaytel's study included about 1,400 free flaps, whereas we included about 300. So, I think the actual rates are a little bit more skewed towards Bandaytel's results. Anyhow, they had a flap survival rate of 89%, whereas ours was 95%. Their complication rate was just over 50%, and ours was 37%. And their salvage rate was just under 50%, while ours was just over 50%. Okay, and now talking about the more interesting part, the challenges in microsurgery. So, actually, there's a lot more research on this. So, here are just some examples of papers that have a discussion about the challenges. But mostly, I'll focus this part on a paper, or actually, it's not been published yet. But it's a study that we've done in Addis Ababa in Ethiopia, together with some of the attendings there. And basically, we sent out a questionnaire to all the plastic surgeons in the five hospitals that perform plastic surgery in Addis. And we had the response rate of 67%, which is actually quite good, I think. And there was a mix of consultants, fellows, and residents that answered. So, in general, I would say that all of the challenges in microsurgery can be divided in three separate categories, patients, doctors, and infrastructure. So, I'll just be going through all three of them. In terms of patients, our study didn't actually look at this in too much detail. But other studies identified that malnutrition and BMI are a big challenge, as, for example, malnutrition can pose a higher anesthetic risk for patients, as well as has worsening risk recovery rates. And what I also found interesting is a study by Giesler from 2005. And they found that their patients in the low-income setting had more post-operative swelling compared to their patients in the high-income setting. And they theorized that this is due to a protein deficiency. So, there is also a public lack of awareness about microsurgery and its benefits. This means that, for example, after in the post-operative care, when it's done in the community, if someone isn't aware of the correct handling, then maybe compliance would be worse, and potentially there could be more complications as well. The general public, if the general public or the general practitioners are not aware about certain procedures that can be done, for example, lymph replantation, then perhaps they don't refer their patients or they refer them late. And there was a study that actually showed, I can't remember the author anymore, but I can have a look at it later, where they found that their patient had been referred quite late in the disease progression. So, this was for oncologic reconstructions in the low-income setting. And thus, the results, the reconstructions were more difficult, and thus the results also a little bit worse. In terms of doctors, I would say that there are two main issues. So, the first thing is a lack of experience. And this goes into two parts. One is that, in general, there just isn't a high enough number of surgeons in the low-income setting. The WHO shows a statistic that in low-income countries, on average, there are 2.5 surgical practitioners, and this includes surgeons, obstetricians, as well as anesthetists, to 100,000 population, which is very, very different from what we're used to here. And then, on top of that, these surgeons that practice in the low-income setting just don't have the experience to perform very complicated microsurgical experience. Bannett also, the same authors from the study I mentioned at the beginning, performed a questionnaire in 2019 of all the plastic surgeons that were signed up to COSEXA, which is the College of Surgeons of East Africa. And what they found was that just under half of them hadn't performed a microsurgical procedure in the last five years. And then, the other part, which is tied to this lack of expertise, oh, I said it wrong before, is an inadequate local microsurgical training. So from our survey, we found that there wasn't any formal training model for microsurgery. And we found that about one fifth of the surgeons that answered didn't have any way to practice microsurgery. And only six of the consultants, that's about half of the consultants that answered, were able to go to a microsurgical course and nobody else. The respondents did find that they could learn from surgical missions, although unfortunately only just about over half of them were able to attend one and participate in a mission. And then I think the biggest set of challenges in microsurgery are to do with infrastructure. And this ranges from materials all the way to theatre capacity. So just for example, talking about materials, two of our hospitals had working microscopes, the other ones didn't. And only one of the hospitals had instruments that were sufficient or sufficiently good to perform a digital replantation. And only about half of our participants actually owned surgical loops. And of these, none of them were residents. And when it comes to more, I guess, theatre issues, I mean, first of all, there is a shortage of trained support staff. So from anesthetists that can perform or can help in certain cases, to nurses, to ICU staff, and so on. And then there's also limited theatre capacity. From the hospitals in our survey, only three of them had regular capacity for cases longer than eight hours. And of these, one of them had capacity once a week, and two of them had capacity once a month. And there was also only two hospitals that had capacity to take a patient back for overnight surgery to do a revision. So you can imagine that the salvage rates might be a little bit worse if they have to wait till the morning to be able to operate again. However, despite all of these challenges, I think there's definitely solutions. And I think actually, over the last few years, we've been really moving in the right direction. The main solutions are, of course, to do with advocacy and policymaking. So for example, raising awareness with health ministries or with governments, so that microsurgery can be included in national healthcare plans. And so that appropriate funding can be given to institutions that do microsurgery. And this funding is very important, that it's long term and actually sustainable. And then the second part is education and collaborative partnerships. So I think the most important thing by far is partnership between surgeons from different countries. And I think, especially now with Zoom and webinars, you can really see people meeting from all over the world and kind of sharing experiences and trying to learn from each other. And I think also in terms of surgical missions. So I was in medical school when I got interested in global surgery. And at that point, there kind of started being a shift in what surgical missions did. So back in the days, it would be that a surgeon from a rich country would come for like a week to a low income setting, perform surgery and leave, sometimes not even do follow up. Whereas now this has completely changed. And the model is now to go and try to train the local surgeons with the aim that in the future, there wouldn't be any more need for surgical missions, you know, like teaching men how to fish kind of thing. Then of course, exchanges and fellowships are always very, very important. And I think one of the only positive things about corona were all the webinars and all the online courses. So that's been really good. And hopefully it continues. And the last thing are cheap training models. So because not everyone has a microsurgery lab to train with, especially in the low income settings. It's important to kind of develop cheap alternatives. And actually, there is a really a lot of literature published on this. For example, there's been studies showing that you can use a smartphone to practice or that you can use chickens instead of or like very cheap silicone arteries and veins. So there's quite a lot of possibilities out there. Anyhow, I think the future of microsurgery in the low income setting is very bright. And I will leave you with that. And I'm happy to answer any questions. Wonderful. Thanks, Rochelle. That's a fantastic talk. It really shines a light on important areas of need in their second world and new developed countries. So while people are thinking, I'd just like to ask you, do you think the differences in the success rate and the salvage rate was putting technical ability aside? Was there differences in post-operative monitoring was was there differences in post-operative monitoring? How frequently did that observations and things are picked up? Is there a handheld Doppler or implantable? Are there more advanced ways of monitoring? Why do you think there was those differences? I think. Thank you for your question. I think it comes down to the fact that our study focus. This is my personal opinion, but I think our study focused mainly on short term surgical missions, whereas the study by Bandai focused on all kinds of microsurgery is performed in Africa. And I think just from experience, when someone goes on a microsurgical mission, you tend to kind of bring like doctors and stuff with you just in case. So first of all, the monitoring is a bit optimized, whereas you can be sure what was the case in the other studies. And on top of that, this is a little bit I'm not sure if this is so good, but because I think the surgical standard of care should always be the same. But I think when a surgical mission is done at a hospital, they tend to have a little bit more resources allocated than normal. So perhaps that also helps with the differences in the rates. I think those would be two things. And then the other thing is that the people that tend to go on the surgical missions to teach and so on tend to be people with loads of experience. So, I mean, it always also comes down to the surgeon performing. And if it's someone that does a microsurgery, you know, once a week or several times a week, compared to someone that only gets a chance to do it once in a while, then, of course, there will be a difference. But I really hope that the further we go along with the years, the more papers there are with outcomes and that the outcomes will be always better. Brilliant. OK, so we have a question from Mahmood Kara. So they ask, how can we encourage more surgical missions that encourage local capacity building? So if I'm understanding correctly, you're asking how people on surgical missions encourage the capacity building, is that correct? Yeah, because as you said, it's not in the capacity in the hospital to have a long procedure or a dedicated pre-plastic surgeon. So how would we encourage that? Yeah, I think so. This is kind of a little bit the harder part for individual surgeons to do because it needs to come down to really a change in hospital policy and just having more resources allocated to this, which is probably the big, I think it's the biggest issue. So the only ways to do it is to keep talking about it, to kind of, you know, you know, if, for example, if a mission comes to kind of make a big deal out of it or like trying to meet with local governments, not for anything else, but just so that they kind of hear it a little bit more and they get used to it or it's in the back of their minds. And, you know, so I think it just comes down to kind of saturating them with microsurgery talk up until they get more fun. And I guess maintaining that link as well. So once the mission has gone, how some telemedicine link up where you have, you know, regular discussions about cases, things like that. Actually, on Sunday, there was a really interesting webinar on a similar topic by the IMC, and it had several basically world experts talking about them going on into low income settings. And I think it's probably still available online, but they talked about all the different ways they try to encourage these connections and how to, how they try to make this like a more sustainable and yearly and more of like a partnership than anything else. And it was quite interesting because they had different methods. And so anyone that's curious about it, that's just really a good webinar to go back and listen to. I would recommend. Yeah. Okay. Thank you very much. One more question. I'll try to find it. And if I find it, I'll send it in the chat. Okay. All right. And last one from Georgie Williams. She says, did you know, Uganda was not listed on the map. There is a microsurgery service in Uganda on the paper by Citron et al in 2016, looking at the challenges of microsurgery. So perhaps there's a bit more more data out there that you could consult. Yeah, absolutely. So this was just some of the details I mentioned. As I said, there's quite a lot of papers out there on the challenges. I just wanted to provide a review and kind of talk about specifically more of the experience that we had in Ethiopia. And on top of it, actually, there's quite a lot of interesting papers. And now I just thought about it. But in terms of capacity building, there's a really, really good paper by Thien. I don't know which year it was published, but basically talks about capacity building in Myanmar. And it really goes through how they started off with a surgical mission and how the local surgeons were becoming more and more self-sufficient every year. So I can really recommend that. Yeah. Yeah. Sounds great. OK, we've got to move on to the next speaker. Thank you very much. So you can move on to Laura. OK, so if we load up Laura's talk. So next, we've got Laura Bologna, who's a resident in plastic surgery, currently in third year at the University of Milano. She's working in the Multimedica Hospital and they reconstructed a microsurgery department and enhanced surgery in one of the best dedicated upper limb units in the country. She's going to be talking to us tonight about great toe pulp flaps, giving us an overview of her experience in the current reconstructive microsurgery service where she works, which has been led by Professor Luigi Troeso at the same hospital. And just looking at the possible indications, the surgical techniques and the clinical outcomes of the GTP flaps. So Laura, over to you. A big thank you for the presentation and a good evening to all the participants. I'm Laura Belloni, Plastic, Reconstructive and Aesthetic resident from the University of Milano. And today I'm going to talk about the reconstruction of a fingertip defect with the Grade II Pulp Flap performed in a multimedical hospital in the Department of Reconstructive and Microsurgery Service of Professor Troisi, Director Professor Pagliardi. The fingertip is a very challenging problem for the reconstructive surgeon. We have a different classification to describe the different injury of this part. And we generally use the Faslera, which describes the different tissue involved in the injury and the direction of the lesion. The main problem is that for the same lesion, we can have a different reconstructive solution. So the main problem is to find the best for the patient, of course. And the soft tissue problems, injuries is very challenging for the surgeon because the surgeon has to try to restore the function of this part. And of course, the sensibility, which is really fundamental for daily life and work activity. So in a very small part, the patient could have a really large discomfort. And as I said before, surgeons have to try to restore the function and of course, try to achieve as much more goals as possible. So not only the function, but also restore the sensibility, avoid pain, minimise donor site morbidity, and of course, listen to the patient and his willings with also the aesthetic too. For example, like nail deformity or contouring of the pulp. And keep in mind all these goals agreed to pulp flap could be a really interesting solution. Also because this flap respects the principle of plastic surgery to replace light with light. Of course, when it's possible, the best solution is always a replantation. But when it's not possible to perform replantation, we have a lot of different solutions. In the literature, we can find different solutions for the reconstruction of this part. So we can choose from our toolbox all the different solutions and sometimes maybe mix up different ones in order to have the best solution for the patient. So the 3-2 pulp flap was first described in 1979 by Bang and Rose. And we have two main points of our surgical technique for the harvesting of the flap. The main point is that we do only a dorsal incision for the harvesting of the flap. Of course, with this incision, we can reach the vessel of the flap, the first dorsal metatarsal artery. And when it's not possible to use it, we use the plantar first metatarsal using the same incision and go deeper. The second point is that we never do suture of the nerve. This is the first case. This is a complete amputation of the soft tissue and bone too. And this is the pre-operatory mark. The second figure is an example of dorsal detection. And the third image is the dorsal scar that we generally close primarily. And this is the result after three months. We have both a good resulting function and this technique too. As you can see, there is a really good contouring of the pulp, the labral skin like the original one, and the color of the skin is really good. This is the second case with an injury of the radial side of the second finger involving soft tissue and the nail too. And this is the result after six months with a good result in the aesthetic and of course in the function too. This is another case with an injury of the fifth finger with a little bone exposure, partial nail bed lesion, and of course the soft tissue too. And this is a really interesting case because we use the flap to restore also the nail bed too. So this will be really useful also for the partial lesion of the nail bed. And this is the result after six months with no nail deformity as you can see. So with a good result. And this is the same patient too. From May 2019 to May 2023, we perform 74 grade 2 pulp flaps. And in our study we selected 28 patients from May 2019 to October 2021 in order to have at least one year of follow up. And we perform this flap in acute injury and also in chronic septic too. Data suggests that the dominant hand is the most involved in the injury, and this is our location case with the second finger most involved. And this is the side flap that we perform from a minimum to 1.5 length to 1.5 width, from maximum to 3.5 to 2.5 dimension. And this is the items that we evaluated with prone subjective evaluation and objective evaluation too. And this is what our patient reported for what they consider pain. We evaluated this with the pain, the vast score, and the patient reported a little pain in the hand, both during movement and rest too. So we had a really good result for the pain, but nearly 43% of the patient reported a cold intolerance. But we see that this intolerance will be better with the passing of time, so with a longer follow up we could have a better result for a cold intolerance and pain too. We also evaluated the Michigan Hand Outcome Questionnaire, and the patient reported a high level in every section of the part examined by this questionnaire, with really good satisfaction, both in function, so for the activity of the daily life, work and sport, but also with a really high level of satisfaction in the aesthetic part. And this is the objective evaluation with the sensitivity. I remember that we never do nerve sutures, so this is our result. We have two main groups, the patient that had extensive finger trauma, and which sensitivity is worse than the patient who had little trauma. And this is the result in patients with less than four months of follow up. The two-point discrimination that we evaluated is 11.5 millimeters, and patients with longer follow up, more than four months, the average of the two-point discrimination is better, it's 10.3, which is worse than the patient with little trauma, that have an average of two-point discrimination with 6.4 millimeters, which is a really good result for the daily life activity of the patient. And in conclusion, our data suggests that the reason they needed to do a nerve suture, because we, especially in a little trauma, because the sensitive recovery is good, and Grade II Pulp Flap is a really good choice, because to restore a like-with-like part, with a really high satisfaction for the aesthetic appearance reported by the patient, with a minimal morbidity at the donor site. And another important thing is that we don't do additional scar in the finger, which is already injured, but we prefer not to do additional scar in the same finger, but take the flap from another site. Thank you for the attention. Thank you, Laura, the lovely talk and the very elegant surgery that you described there. Right, well, people are thinking of questions. I'd just like to ask you, in terms of your long-term outcomes that you've seen, whenever there's hand trauma, there's always things like cold intolerance and CRPS and things like that. Obviously, your patients are undergoing complex reconstructive microsurgery, lots of steps and lots of things that can go wrong. But in the long term, firstly, how long is your longest follow-up and what kind of effects are you seeing in those patients? In this study, follow-up is a little bit more than one year. So, of course, we want to try to register all the results of this flap. Yes, the most important problem that patients report is the cold intolerance. But we see that this will become better with the passing of time. So we are waiting for more follow-up to try to understand how it will go in the future for the patient. Pain is not reported, not really reported from the patient. They are really satisfied also with pain. Just a little pain is reported, but this is sure will become better during time. But this is not a problem. The main problem is the cold intolerance. But we see that this will become better. So we will see in time if this will be better. Brilliant. And obviously, with the thumb defect you presented, that's not a very obvious disability. But in the kind of the smaller defects you've seen, I mean, my first thought was, you know, just to shorten the bone and close the skin and then kind of manage the scar. How small is too small for this kind of reconstructive option that you presented? Yeah, we always try to find the best solution for the patient. So even if it's a little defect, the fingertip is really important for all the activity for the patient, for daily life. So we've tried to find the best solution. So even if it's a little defect, the fingertip is really important for all the activity for the patient, for daily life. So we prefer to give the patient this choice. A lot of the patients accept it because maybe they are scared about long anesthesia, long surgery, which is not so long. We perform this step in a maximum of three, four hours. But we prefer to give the patient the quality of life they had before the injury. So this is a choice that the patient has not all accepted, but the ones which accept it, they are quite happy of the result. Your fellow panelist is asking, are you doing this flap in an emergency setting when the patient first comes in? Or do you stabilize and wait temporarily with the dressing and then do a secondary reconstruction? Yeah, generally we do also in an acute injury trauma. But generally, maybe it's not the same day because it's not generally an emergency, this kind of trauma with little trauma. So the patient can wait, but generally we do it also in acute trauma. Also in three days we perform this flap for the acute injury and also in the chronic setting too. Brilliant, thank you very much. I don't think there's any more questions, so we'll move on to our final speaker. Can we start loading up Tom's talk, please? Right, so last and certainly not least, we've got my colleague Tom Andrew, who's a NIHR-funded academic plastic surgery registrar in the UK, based in North England in Newcastle. He's also the current plaster research rep, sits on the committee with myself, and he's from the Blood Cancer Research UK Clinical Fellowship. In the past, he's completed a postdoc in Stanford and a postgraduate research also at Johns Hopkins in Baltimore. His interests include innovation in the head and neck and contagious malignancies. He's developed various methodologies in artificial intelligence, stem cell biology, and tissue engineering. So tonight he'll be talking about ways of identifying and understanding the sexual differences in bone remodelling in plastic surgery patients. And by understanding these mechanisms, hopefully you can present a clinical strategy to accelerate bone remodelling using localised hormone therapy. So Tom, take it away. Excellent, thanks for that Vic. So yeah, good evening or good afternoon, depending on your time zone. As Vic said, my name is Tom Andrew and I'm an academic plastic surgeon in the UK and the BAPRAS research lead. It's a real pleasure to talk to the ASBS Global Partners webinar series. And the talk I'm discussing really highlights the importance of meetings exactly like this one. It demonstrates cross-continental collaboration. As a UK trainee, I was given the opportunity to complete my postdoctorate at Stanford. And the research question really generated from clinical observations as a plastic surgeon. I was noticing significant differences in patients' time to mobilise, post-operative complications and even death, particularly when looking at fractures predominantly of the lower limb. And I wondered when we saw these marked differences in outcomes, they were often driven by age and most clearly seen when considering the postmenopausal patient who had osteoporotic fractures. Now, the aim of this project is to try and make sense of the sexual differences in bone healing from a plastic surgery perspective. And really demonstrate the cycle of establishing a clinical problem, looking into the basic science or the biochemistry to find the solution and then bring that back full circle for a bedside translational outcome. So I have low financial interests. And often we can think of skeletal surgery or bone healing problems as the domain of the orthopaedic surgeon. But as the modern reconstructive surgeon, it's essential for us to understand tissues beyond the soft tissue alone. As we think about it, as plastic surgeons, we're often dealing with the bone, whether that ranges from metacarpal fractures to craniofacial surgery. To mandibular reconstruction with a free flap. And the example I've used here is a really novel and interesting way of managing these sorts of bony problems. This is a case provided by one of my attendings, Juan Berner, who is a lower limb expert. And this was a case where the orthopaedic team came to us and needed a solution. This is a patient who had multiple stage debridement and removal of metalwork for an infected fracture. When the wound was cleaned, an ALT free flap was performed. But in conjunction with a medial femoral condyle periosteal flap. Which is a bone flap supplied by the descending genicular artery. This was plumbed into the ALT and provided a vascularized osteogenic periosteum for the bone defect. So we've talked about the sexual differences and we'll use the term sexual dimorphism. And this refers to the morphological differences between sex. And is seen throughout biology, whether it be from a lion's mane to the feathers of a peacock. And these are driven by regulations in sex hormones. Clinically, Chang observed that the female sex was a significant univariant predictor for graft failure in vascularized bone grafts in scaphoid nonunion. But perhaps we see this most significantly when we look at lower limb fractures. Particularly osteoporotic lower limb fractures. A 50 year old Caucasian woman has a 50% lifetime risk of developing an osteoporotic fracture. and of patients that develop lower limb fractures, there's a 27% mortality rate within one year, which is higher than myocardial infarction. And this fits in with the growing consensus from the American College of Surgeons, the UK guidelines and other European guidelines that certainly open lower limb injury should be managed between the plastic surgeon and the orthopaedic team in collaboration. And it's not just these patients are more prone to fracture, we notice significant delays in bone healing, where only a third of these patients develop pre-fracture levels of mobility. And again, we've got to look at real world examples of this. This is another case provided by Juan Berner from just two weeks ago. This was a female patient who had an open fracture in January while skiing. She was treated locally in France with an open washout closure and an external Hoffman style frame, which you can see in the image on the left. She was repatriated to the UK and temporary fixation was changed for a permanent circular frame. And at this time, the bone fixation was adequate, as you can see from the image in the middle. The image on the right, sorry, the image in the middle was from January. The image on the right is from May. We see no bony union during this time and she developed subsequent wound breakdown. So this case really generates the really highlights the question that can we do anything to accelerate bone healing in these female patients, if not only to heal bone function, but also the effects it has on the soft tissues. And there are a number of systemic hormones and transcription factors that regulate proliferation and differentiation in osteoblasts and osteoclasts. And the mechanism for sexually dimorphic differences in bone regeneration still remains elusive. The current focus for treatment is on fracture prevention with bisphosphonates. But given the frequency of traumatic fracture and iatrogenic fracture, which we see in plastic surgery, we need to ask ourselves the question, is there a way that we can accelerate this impaired bone healing in patients at the stem cell level? And in starting to address this problem, we need to ask the question, do skeletal stem cells exist? And our group was able to publish in Cell and they were able for the first time to isolate skeletal stem cells, which formed skeletal lineage, including bone cartilage and bone marrow. Unlike mesenchymal stem cells did not form adipose tissues, endothelial cells or hematopoietic tissue. This forms part of the growing evidence that organs are not made up of mesenchymal stem cells, but of a combination of different tissue lineage restricted stem cells. And this is further supported by the current literature. There's a case in New England Journal of Medicine where a patient had intravitreal injections of so-called mesenchymal stem cells for age related macular degeneration and unfortunately developed severe visual loss in the cases that were formed. So next we need to ask the question, how does this, this was the stem cell was identified in mice originally, we need to link this into the clinical translation. So we needed to ask the question, do skeletal stem cells exist in humans? And our team again were able to publish in Cell and identified a self-renewing, multipotent human skeletal stem cell. They were able to isolate this from adults, from fetal tissue, and also from induced pluripotent stem cells. We were able to demonstrate that these skeletal stem cells were present by injecting them into the kidneys of mice and demonstrating that they formed bone in this environment. We see a local response to stem cell expansion in the response to injury. So in this study, we looked to understand if sex hormones can affect factor healing initially in mice. And to do this, we performed oophorectomy, which is a well-described model for inducing menopause in mice. We also performed sham surgery, where you perform a laparotomy, identify the ovaries and don't remove them. This creates the physiological response to surgery without removing the ovaries. And we compared this to male mice. We also perform orchidectomy on several mice as well. Now, what we found was we found, you can see the images below, significantly larger fractures in the male mice and the sham female mice when compared to the oophorectomized mice. We then performed mechanical strength testing, and we see a significant reduction in the strength of the oophorectomized mice bony callus after seven days. We also performed micro-CT, and again, we see a significant reduction. And actually, if we look at the images, you see the image in the centre, which shows nonunion after seven days in the oophorectomized group. These findings suggest that bony healing is dependent on ovarian function in female mice. So, then we asked the question, these functional differences that we see, do these exist at the stem cell level? So, what we did is we isolated skeletal stem cells, and we identified that following fracture, we saw approximately a fourfold increase in the number of stem cells. And this is, we propose a natural mechanism in order to recruit more stem cells in order to heal the bone. Interestingly, what we see in the group that had oophorectomy, we see no response following fracture. So, no increase in the number of stem cells. And then we tested whether these differences occur in cellular proliferation using colony forming units and osteogenic differentiation. And we see, again, a significant reduction in both bone formation and cell proliferation in these groups. These results really demonstrate that in mouse skeletal activity, that stem cells are differentially regulated in male and female mice. So, we were aware that the ovaries produce several really important hormones for survival, including luteinizing hormone, testosterone, progesterone. And through optimization studies, we were able to identify that estrogen has a key role in restricted stem cell response. In order to confirm this, we removed the ovaries in mice and administered 17 beta estradiol subcutaneous pellets. So, we give exogenous estrogen. What we found is we were able to provide super physiological levels of serum estrogen, which resulted in super physiological bone mineral density strength, mechanical strength of the bone, as well as significant differences in bone deposition in histological analysis. These findings really display that sexual dimorphism is driven by estrogen in the skeletal stem cell regeneration. So, to determine whether this rescue was associated with changes within the stem cell itself, we profiled the cellular composition of the fractures using FACS analysis, which is the fluorescence activated cell sorting, which is a form of flow cytometry, which allows us to filter the entire bony callus to isolate the pure skeletal stem cells. We then perform transcriptomic analysis of these pure populations using gene chip analysis of the mRNA, and we were able to identify molecular differences in skeletal stem cell signaling between each group. Most notably, we see ESR2 on the genetic profile heat map. We see a significant increase in expression in the sham mice, which is significantly dropped in euphorectomized mice, as well as male mice. But in order to understand whether this was occurring in the microenvironment, we perform single cell RNA sequencing, which is a method of examining gene expression levels at the individual cell level. We found co-expression of estrogen receptor with multiple skeletogenic signaling pathways, including BMP1. So, these results really demonstrate that the genes are differentially regulated in stem cells. So, then we need to look at the case in humans. We've talked about mice, what's happening in humans? So, to address this, we identified highly purified human skeletal stem cells. We isolated these from fracture calluses, but also from uninjured femoral heads, which were taken from total hip arthroplasties. We measured the estradiol levels of these patients and interestingly found similar levels in postmenopausal women as we found in young and elderly adult males. Despite this similarity in estrogen levels, we found a significant reduction in ESR2 expression. We can see a dark blue expression in the male, which actually shows negative expression of estrogen receptor 2, demonstrating that these trends parallel those we saw initially with mice. So, to confirm whether the skeletal stem cell activity in humans was directly regulated, we performed functional analysis of the stem cells, and we did this by creating a gradient concentration of estrogen, which is the graph in the middle. We see it ranges from zero nanomoles to 100 nanomoles, and we can clearly see in females a dose-dependent response when we increase the cells to estrogen in the environment. But interestingly, when we add in the male cases, we see no difference and no response depending on estrogen levels in male skeletal stem cells. So, we've developed this in a well-established model in both humans and in mice, but really to validate this, we needed to do this in an estrogen receptor 2 knockout mouse. So, we bred and developed this mouse with a Flux, and we were able to block the expression of ESR2 gene. When we did this, when we did this, we saw a significant reduction in stem cell expansion following fracture. We also replicated this in humans. So, we used SHRNA to silence the ESR2 gene, and that's a method of gene editing in order to block gene expression. These results showed that ESR2 is necessary to female skeletal stem cells, but not to male. And we can see this most clearly when we look at the alizarin red. So, that's bone formation. Red is the bone formation on the image on the far right. We can see in the female knockout group no bone formation at all, whereas in the male knockout group, we see consistent bone formation. So, we've identified a solution which is pretty simple. We can give exogenous estrogen to treat these fractures and restore bone healing capacity. However, the problem with giving systemic estrogen are the significant long-term effects, including breast cancer, endometrial cancer, and VTE risk. So, in order to address this, we developed a degradable PLGA nanoparticle scaffold in order to deliver highly localized, temporally regulated, very low dose of estrogen. And what we can see from the graph in the bottom left, we can see no difference in estrogen levels when we treat the the mouse with the localized estrogen rescue. Despite seeing no difference in serum levels, we see a match in terms of strength, in terms of mechanical strength testing, and in terms of skeletal stem cell recruitment and activity. These results indicate that the local delivery of estradiol to the skeletal stem cell niece rescues the deficit C, really emphasizing the importance of signaling of the skeletal stem cell. So, collectively, these results demonstrate targeted hormone therapy with localized estrogen can correct specific skeletal stem cell defects, bypassing the harmful effects of systemic estrogen therapy. And within that, we've been able to identify specific pathways involved in this process, including ESR2 and BMP1. Really interesting, we were able to replicate this in a 26-month-old aged female mouse, which is equivalent, let's say, in human ages of 100 years old. And we were able to restore bone healing in these mice to adolescent levels with the localized treatment. So, historically, we did not think that stem cells could demonstrate sexual dimorphism. We thought they were the same. And these findings provide new important biological insight into understanding the stem cell demonstrating skeletal dimorphism. Here, we report that estrogen acts directly on females, but not male skeletal stem cells. And we were fortunate enough to publish this paper in Nature. Now, moving forward, we have to ask the question, how does this fit in for translational medicine? And for this, we were able to develop a nanoparticle and estrogen scaffold and apply this in 17 human specimens, providing real true translational opportunity in targeting the stem cell niche for the plastic surgeon in the real-world clinical environment. And we really see this in the future as being an opportunity to accelerate female bone healing, particularly in the postmenopausal patient across plastic surgery. So, it's been a pleasure talking to you today, and I'd like to welcome any questions from the audience. Thank you. All right, thanks very much, Tom. That's a fascinating talk, encompassing many aspects of research and hopefully translational outcomes. I guess a quick question while people are thinking, how do you think this is all affecting osteoclast activity? You described very nicely the impact on osteoblast and bone differentiation and all that. How do you think osteoclasts are affected? Yeah, it's an interesting question, Vic, because when we think of osteoporosis, we think of high cellular turnover. So, we think of osteoclastic activity rather than the building blocks of the bone. But what we found was estrogen actually was involved in the anabolic processes of bone healing rather than the catabolic processes. So, we actually did trap staining on the samples, and we found no difference in osteoclast activity, which really fits in with a clinical problem, which is a delay in wound healing, not just an increase in a reduction in bone mineral density, but the fact that these bones aren't healing in the same way, which means these are the areas we really need to target as surgeons in order to get better results for our patients. And probably something from my own research in craniofacial genetics. So, do you think there is an impact in, or can you slide any genetic mutations in knockdown mice or key regulators of osteogenesis and differentiation, such as the FGFR pathways, and see what impact that would have in the various mice population you described? Yeah, no, that's a really good question. And part of the reason why we use a flox mouse, because we initially saw genetic compensation. So, we found alternative pathways and effectively bypassed the pathway that we were interested in. So, that's why we developed a system of mouse where we could switch on and off that gene expression, and able to demonstrate those real-world changes rather than, you know, in a very controlled lab-based environment. So, I guess, where do you see it going next? What might be your next steps? Well, we would like to see this eventually, you know, we're working on it being adopted in clinical practice. And really, it starts by establishing a clinical trial with the translational team, and really applying the nanoparticle scaffold that we've developed in patients. So, we've done that on 17 so far. We'd like to expand that number, and then, you know, we really see this as a great solution to, you know, a relatively common problem. Let's see what's going in the Q&A. So, Mamoukara is asking, is the translational material you describe at the end available for fracture treatment now? For example, he's a clinician in Canada, and can he get it to the next lady who needs it? I think it's quite fair, yeah. That's kind of what he's asking. And his second question is, for local treatments, for open injuries, what about closed fractures? And how would you treat them with localised oestrogen and not systemic oestrogen? So, yeah, so let me just go over the second question. Local treatment would be used for open injuries. Yeah, so yeah, I mean, closed fractures, if you are managing them with splinting, of course, we wouldn't recommend opening up this patient to do this. We see this as being these patients requiring open reduction and internal fixation using this at this stage, or in revisional treatment in cases of non-union. And in answer to the first question, it's not currently available elsewhere outside a research environment, but we hope in the near future it will be. Any more questions? So if we could invite Lariska and Laura back on, turn the cameras on, that'd be great. Yeah, Lariska. Laura, are you still there? Maybe. Okay. Yeah, yeah. Oh, there you are. Hi, hi. Right. I think all the questions have been answered. Anyone else has any burning questions? The chancellor panel is here now. Give me a few seconds to think. Just lots of nice comments. Excellent. All right, let's wrap up this evening's session. So thank you to our three speakers, Arusha Subrahm, Laura Bologna and Tom Andrews. It's really fascinating hearing what you guys have been up to and where the kind of future directions are for our speciality. I'd like to thank everyone joining us tonight, this afternoon or this morning, wherever you are. It's great to have you with us and a special thanks to the ASPS for hosting us so nicely. And thanks Romina, as always, to Madison and to Amy. So thank you everyone and see you later.

plastic surgery

microsurgery

reconstructive surgery

fingertip reconstruction

Great Toe Pulp Flap

bone healing

hormone therapy

PLGA nanoparticle

surgical partnerships

patient outcomes