Section: CME Category: Diabetic Foot

Terminal Outcomes In The Diabetic Foot - How Does The Timeline Of Podiatric Biomechanical Intervention Modify Them

Robert Eckles, DPM, MPH

Robert Eckles, DPM, MPH discusses current interventions in podiatric medicine for the diabetic foot. Dr Eckles discusses what current treatment modalities have shown to be successful and what modalities are lacking research. He also highlights interventions that modify the terminal outcome in a diabetic foot.

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Goals and Objectives
  1. Report that people with diabetes are living longer, amputation rates have decreased, and there are many procedural interventions that have been proven effective in preventing major amputation.
  2. Report prevention of charcot deformity is not well defined
  3. Review what podiatric interventions modify the terminal outcomes in a diabetic foot.
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  • CPME (Credits: 0.75)

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    Release Date: 06/07/2018 Expiration Date: 12/31/2020

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  • Lecture Transcript
  • TAPE STARTS – [00:00]


    Speaker: It's my distinct pleasure to bring up to the podium Dr. Bob Eckles. Bob and I worked extremely close together at the college. He is our clinical dean. So he is responsible for the clinical education of the third and fourth year students. He is also dean for graduate medical education, so he oversees our CME programs and our residency program and we are usually solving the problem of the world at 6:30 every morning in his office, but since we still got meeting to try to solve, I guess, we're not doing a very good job at solving them. But anyway, Bob is going to talk to us on biomechanics and diabetic foot. I forgot the exact title but I am sure you are going to enjoy the lecture. He is a wonderful speaker and very knowledgeable guy. So Bob, it's all yours.

    [Applaud]

    Dr. Robert Eckles: Thank you so much and as Mike said earlier thank you all for hanging around. It has been a very long productive weekend. The title, I guess I win the award for the most syllables in the title; it's basically summarized this way. If you look at the screen representing all the various modalities and techniques and things that we're now doing about the diabetic foot, there is something missing from this slide. And I think it reflects what's often missing in our clinical management of patients with diabetes and that is biomechanics. I think we are all well-trained in biomechanics, but for some reason and I will go into what I think those reasons are, we fail to navigate that and assert ourselves that way. I have no financial disclosures here, although I do have a notable bias towards biomechanics and public health perspective, which will come through.

    [02:03]

    My objectives revolve around what is the good news, where we have been and where are we now. There is unfortunately plenty of bad news to reflect on. I think we pat ourselves in the back often in our outcomes. There is plenty of room to go. There is plenty of room still to move the dial, move the needle on the dial. I hope to summarize what I think works in lower extremity diabetes management. And so if we start with the good news, I think we all know and we all agree we see this in our practices that amputation rates have decreased. People with diabetes live longer. In fact, people are starting to die from conditions somewhat related to diabetes that we never anticipated. I'm thinking in particular the encephalopathy that we know is beginning to assert itself in patients who have been hyperglycemic for four and five and six decades. We also know that we benefit and our patient benefit from the many technological and procedural advances that just did not exist 10, 20, 30 years ago. The bad news is that globally prevention of first ulceration is still not very good and this is probably the single biggest fact that I will present you with today that it is such a determinant of final outcome that in essence the thesis of what I am going to say is we should be working on that one thing and I'll obviously talk more and more about that.

    [04:02]

    Re-ulceration, amputation and re-amputation rates are very high. Sequential amputation back when I was in training referred to as salami surgery, that still is unfortunately the reality despite the overall fall in amputation rates. Prevention of Charcot deformity is understood and that we all know who is vulnerable, but I think poorly implemented and the few of us tend to do anything about it other than chart that the patient is neuropathic and [indecipherable] [04:41] sites and inform the patient say you know you are numb. You should pay attention to your feet. That's not a strategy. Fatality rates associated with amputation still remain high. We get to what works in the end and of course we will talk about some of the biomechanics. There are few sentinel moments in the natural history of diabetes that are worth noting if only for a moment that in 1922, for example, when insulin was first made available, fatality rates virtually disappeared in a very short period of time. We have the ability to reflect even with our own practice lives and in our lives as podiatrist, on a similar level of success, although it was not due to any one thing. Obviously, the 65% reduction in amputation rates over this 12-year period came about because of many, many things. It wasn't so single therapy oriented as insulin was, but it was as great moment in the natural history of this disease. So I am kind of saying the good things.

    [06:01]

    And these align with that study where you can see that the sites of amputation and frequencies of those amputation procedures steadily decline from the 90s right out until about 10 years ago and we can see that age is no longer a factor in determining who is going to be amputated that elderly people have about the same risk factors and vulnerability on admission and discharge as anyone else. But this is an article that came out in New England Journal last year. Armstrong and Bolton rolls out the carpet for where the bad news is that 40% of the patients have recurrent ulcer within a year. If you go out to three years, it's 65%. Worse, this first ulcer that I mentioned before over a 10-year period doubles the risk that the individual will die from any cause. So this is again the statistic that’s worth tracking and paying attention to. Globally, United States doesn't do as well you would hope as we would hope given the level of technology and the money that we throw at this particular problem, but we are in good company. Germany and Denmark do worse than we do. What I don't understand is how other countries in the eurozone; Sweden, UK, France and Switzerland do so much better. I am sure the answer is in the literature, I just don't know it. And as I mentioned, fatality is an unfortunate consequence. We know that the more proximal the amputations site, the more risk there is to that individual's life over a short number of years.

    [08:00]

    This constitutes an image, which represents a fairly well-known statistic in the relationship of neuropathic ulcer and amputation relative to lung cancer is almost equipoise. It's almost one to one and many people have used that statistic and for good reason. I will come back to lung cancer later. We also know that comorbidities -- presence of comorbidities is startling the significance in terms of where these patients end up. Compared to the patient with one comorbidity and I would like to know that patient as I don't -- most patients that we see have two, three and four. These individuals face an extreme uphill battle when they are taken for amputation. A person with four or five morbidities seven times more likely to die than an individual with just one. Couple of years ago, the international working group on diabetic foot published some data. And they reached a lot of conclusions. This was a collaborative effort to produce this document. And interestingly, their "the evidence for the use of interventions to prevent a first foot ulcer practically non-existent." Now, they group a lot of other more significant pathologic events in here but this one stands alone and I think as I said before represent something where we need to be focused. Also from the same working group, their conclusion that we're pretty good about intervening, pretty good about using mechanical intervention to prevent recurrent wounds but no strategies working yet to prevent the first wound.

    [10:04]

    [indecipherable] [10:06] and I had the privilege of meeting professor Jeff Cole [phonetic] about a year ago in Ireland on the subject of wound dressings. I think it pulls the rug out of some of our comfort zone in that we tend to think that our wound dressings are profoundly effective in cases where there are comorbidities, PAD and so forth, but they are not. All of them are better than what we had 20, 30 and 40 years ago. But none of them are affected in the presence of intractable PAD and biomechanics, which are inconsistent with healing. One of the reasons that I think the bad news continues to resonate here has to do with the frequency with which we re-amputate. There are lot of studies on this and I am going to reflect on a couple of them here. It's no secret. Digital amputations frequently get revised to transmetatarsal, transmetatarsal to BK, more proximal amputations, Lisfranc, Chopart and Syme tend not to hold up very well. They are less frequently done to begin with but the revision rate per procedure is quite high. And I would assert that while arterial disease is clearly in evidence here and effects outcome that most of these revisions are secondary to uncontrolled biomechanical sequelae of the initial procedure. This was a very interesting article where they look for 11 years at the sequelae of first ray amputation.

    [12:00]

    And I jumped ahead of myself to reveal this shaded-in area where of the 59 feet, which had partial first ray amputation, 25 of them went on to trans met or BK. It's a very significant outcome, which as I said I would assert in some ways predictable and perhaps remediable. The worse part of this is the mortality rate associated with that change that over that same period almost half of the individuals in this groups that were studied died. If you look at primary proximal amputations and this is a study done with people who are profoundly ill. So the data can be interpreted through that lens, but if you look at the outcome here and I am very sorry for all the red and shading and so forth, but Chopart's amputation was performed in 45.8% of patients, also recurrence developed in 31% of those. Major amputation was subsequently required in 27% and again nearly half of these individuals died. So this starts to frame outcomes here in less than a favorable way. I want to talk a little bit about Charcot. Even though only depending what you read 4% to 7% of individuals with diabetes develop it. Plantar pressure, micro trauma, abnormal mechanics clearly related to the development of it and of course we don't know everything there is to know about Charcot disease. We don't know specifically why 10 people who we consider vulnerable if you look at that those people over time, three of them will acquire it and the other seven will not.

    [14:07]

    What we do know is that we go from A to B. Almost predictably, these radiographs almost always look the same and we go to see with an attempt at reconstruction, which I think we would all agree might preserve a plantigrade foot but not necessarily a functional foot. Certainly, a foot that's prone to re-ulceration and other issues over time. As I said we aren't quite sure no one knows exactly why the Charcot deformity develops. I jumped across a span of number of years and two references here that basically the bold and red kind of highlight my focus when it comes to Charcot and where I think we have an opportunity to intervene. Unfavorable mechanical stress is in most cases left intact in our interaction with patients who are at risk. And I am sorry this is so dark but I try to lighten it unsuccessfully, but this article from 2013 looked at a small number of patients, diabetic who over the course of short amount of time went from a rectus foot or moderate planus foot to a significantly planus foot in ways that we would find totally predictable and I would assert totally preventable or modifiable. That's my biomechanical input there that calcaneal inclination, talar declination and so forth. Talar calcaneal angles. This is a logical progression. It's a sequence that should not surprise us.

    [16:03]

    Unfortunately, it leads to very challenging debilitating disorders. And it makes me wonder what we should be doing for the patients who we find to be at risk for Charcot. It's clearly not enough to say you are neuropathic. It's probably not enough to say you are neuropathic, you should be in a diabetic shoe. Most diabetic shoes are not particular functional devices. They are made to prevent wounding. They are not made to sagitally plane move a patient from heel strike to toe. They are not meant to provide rigid support to longitudinal medial arch, which is vulnerable to micro trauma and stress. And I think that they are soft tissue issues, which develop in a patient with Charcot before the osseous events are evident on x-ray that we could screen for and I am not trying to jump up business for radiology, but I think that if we did take the time to look at our plantigrade patients and identify the planus once and if we see them over time, refer them for evaluation, we are going to see the very, very early signs of change that might allow us to intervene so we can get ahead of this. Another part of this puzzle, which I think is modifiable by us has to do with sedentary behavior and I found this study, again this is from last year, of great interest. It's known as regard study that basically gave lots and lots of people accelerometers and they have them walk around and they basically tracked how much each group walked around. And surprise, surprise.

    [18:00]

    The groups that walked the least were the obese and diabetic. Out here in quartile 3 and quartile 4, these were the most vulnerable groups identified in this study. Then they tracked them for a period of time to see what happened to them. And here is quartile 3 in terms of cumulative mortality and here is quartile 4 in terms of quartile mortality. So there are significant changes in mortality associated with sedentary life style and again I am going to assert that this is our business that we often see these individuals more frequently than they see their primary care practitioners and that this is something that we could if we wanted to take the range on to try to get out patients to be more and more active. I loved the title of this article. I believe it, sitting is the new smoking. Then we can look back 10 to 20 years from now at the degree of sedentary life style, but that we promote it and reflect back on the morbidity that is caused and we wish we had done more. As I said before, I think this is modifiable by our input, by the input of others and there are patients who will do better if we are able to achieve that. So why not just real quickly summarize I think what does work in the end. Assertive management of risk populations, aggressive debridement, negative pressure, total contact casting, appropriate antibiotics, we have amazing products at our disposal now, amazing wound care products and well considered surgical management.

    [20:02]

    I am going to assert here that preventative prophylactic surgical management is in fact biomechanical tool that we underutilize. What really works, what else is sentinel change in the natural history of diabetes is endovascular intervention. Three studies that have been reported within the last 10 years in its different forms and stents show patency out 18 to 24 months. Stents are imperfect. They require a lot of skill to put in and they eventually degrade, but all of these interventions consistently show that patency can be achieved at least long enough to allow the wound to heal. We all know and this just underscores it, people with no PAD do better than people with PAD and that's a kind of no-brainer. So when I put the slide up at the very beginning, it reflected a lot of what I would consider to be tactics. And when patients come in to your office and they got a wound, they got an infection, you can only respond tactically at that point. But I think that the data started to show us that our success rates are starting to level off, that the dramatic declines in amputation rates, dramatic declines in fatality rates are leveling off. Nothing -- even though we are pushing harder, harder and harder, we're not going to move that outcome because we are not implementing strategy that's working at the beginning of the process at first wounding. I would like to see a word frame like this that accompanies the one that I began the presentation with where our examination and our management plan includes all of these things.

    [22:01]

    I know that's a big ask. But let me ask a question, let me try to illustrate something. Here is the patient who comes in to see you or me. No particular complaints. Primary care doctor said you got to go see the podiatrist. With your examination, you find he or she is insensate and you find that this person has a low ABI and relatively non-palpable pedal pulses. We don't blink. We do what we have to do here. We refer this individual for vascular assessment, for intervention. I think we all do that. But let me make a change. Take away the vascular stuff and insert ankle equinus and hallux limitus and fat pad atrophy. Now the alarm bells that ran a moment ago don't ring so much. We might chart it. We might not even do these things. Intervention here, I think, is equally important to the long-term outcome that individual is going to have and yet we frequently and I am going to pat myself on the back. I'm going to say mea culpa, we don't intervene. It's more difficult. It's not medical or surgical management. It requires durable medical goods, although in the case of ankle equinus, it may require surgery that you would have to sell as a prophylactic measure and method of intervention. We understand patients with diabetes are different mechanically. They have reduced cadence and stride length, double support dominates. They have co-contraction of muscle groups, decreased range of motion.

    [24:02]

    They have more sway. We don't typically evaluate for theses nor do we intervene and you can't intervene in many of these. There are hidden path of mechanics we need to take advantage of. Shears, sway the mind, type 3 diabetes, diabetes encephalopathy. We don't consider this. And frequently unfortunately, we don't consider the sequelae of the amputations, which becomes necessary from a biomechanical point of view. I'm going to speak just for a moment about shear because I am fascinated by it. This slide illustrates a very obvious skin lesion that is caused by shear. Sometimes we are not so lucky that the skin gives us this signal. Shear is very difficult to measure, which is one of the reasons -- it's -- as it was referred to their podiatric dark matter. But what we do know about it is that the area of peak shear is not necessarily the place where peak pressure is the highest. These references would indicate that they can be very distinct anatomical sites. We know based on work like this that individuals with neuropathy are more likely to have plantar shear compared to controlled subjects. In the end, we find some data suggest that the patient is much more likely to ulcerate at the site where there is shear stress compared to simple planar pressure stress and yet we don't take the steps. Admittedly, it's difficult to identify and intervene. So what I want you to do. I want you to do something functional for your patient in terms of biomechanical assessment.

    [26:02]

    I want you to consider surgically intervening. I want you to make a functional foot orthosis. I have a prescription for you later. I want you to consider AFOs. When the patient moves from simple pes planus to unstable foot and therefore at risk of many, many challenging pathologies, do more than just a diabetic shoe. When you do put them in a shoe, do better than just a stiff flat shoe and get involved with these individuals in terms of their fitness. And I said earlier I was going to come back to lung cancer and I will because the analogy that I will use is that lung cancer fatality rates are low in United States right now. But they are not low because we are so good at treating cancer. They are good and they are low because we got people to stop smoking. So that's my point about tactical versus strategic intervention. Again, from the Armstrong and Bolton article, the greatest outcomes that they were able to find in terms of intervention were in therapeutic footwear and surgical intervention categories. This is a really good article on the subject of surgical intervention for wound healing. It doesn't deal specifically with prophylactic surgery to prevent wounding, but this article reveals a lot of data that supports the use of intervention in ways that previously 20, 30 years ago would have been considered unwise. Now, I am going to jump to the next couple of slides because they relate to the effect of diabetic footwear. As you can see in the white font here, diabetic shoes off load.

    [28:01]

    We all know that, but what is interesting is that when you add customization to it, you actually do better. When you have domes and extra supported devices, heel lifts in the shoes, you actually do better. So this is my prescription for foot orthosis and patients with diabetes mellitus. Use rigid materials. I stole this from a lab whose name will not be revealed and I circled the diabetic accommodative box, which I will urge you not to circle or check when you are writing this prescription. I think fundamentally these individuals have functional needs. They require rigidity. They require support. They require sagittal plane facilitation just like any other patient. Of course, they need soft tissue supplementation. They need strategic placement of accommodative or mechanically active material such as PTFE, which is great for reducing shear. And these patients should be placed in shoes that go above and beyond the traditional stiff flat sole diabetic shoe that patients don't even want to wear. So I made a little image here. Hypothetical patient who this year is prediabetc, next year; diabetes diagnosis is confirmed, develops a wound, amputation one, two and seven years from now unfortunately succumbs. Medical management represented in red dollar bills, podiatric in yellow. If we start with a little bit of medical management here, it obviously accelerates as this person acquires morbidities and ultimately dies.

    [30:03]

    The podiatric medical management, investment of time and dollars roughly corresponds, but what if we did that? What if we put our time and money here before that first wound? We would not always win, but this is the stopping smoking moment. I think we need to grab it. I think we need to move with it. So what I am asking you to do carefully assess, look for hidden pathologies, do surgery, remediate the deformities that you know are going to cause ulceration. Don't just check the box on the orthotic prescription form. Design something that works, put that person in a shoe that works and be intrusive into that person's life. It's hard to get somebody to unwind a lifetime of sedentary behavior. But clearly it's their lives that are at stake and I think it's increasingly our responsibility. So let's move to dial on that and I thank you.



    TAPE ENDS - [31:15]