Harold Schoenhaus, DPM will discuss the use of bone stimulators in patients at risk for poor bone healing. Dr Schoenhaus will review the different types of bone stimulators available and focus on advantages and disadvantages of each.
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Harold Schoenhaus, DPM
Surgical Editor for PRESENT e-Learning
Penn-Presbyterian Medical Center
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Bob: Okay. For our next lecture, it’s a pleasure to welcome somebody well-known to us who happens to be the Chair of Superbones Superwounds, Dr. Harold Schoenhaus. A friend and a long time colleague who hales from both Philadelphia and West Palm Beach, I guess, down in Florida. Dr. Schoenhaus has been a teacher to many, many people in this room and a colleague to many others. He has a wealth of experience. He has dedicated a lot of his life to education and works very, very hard with the PRESENT team to bring the meetings and improve the quality of the meetings to you all. With that said, Dr. Schoenhaus is going to be talking about bone stimulation for nonunions and difficult fracture. Let’s welcome Dr. Harold Schoenhaus.
Harold Schoenhaus: Thank you, Bob. I do want to state that over the years with PRESENT, we have certainly attempted to educate and lead the profession through the educational forum and environment, providing the state of the art of what’s being done today, what’s available, and what’s in the future. It can’t be done effectively without co-chairs of meetings such as Bob Frykberg who is a dear friend of mine, great educator, and the PRESENT team. Obviously, seeing the amount of people here on a Friday, I’m pleased. I can’t tell you just how pleased I am. I thank you for your time, the amount of time you spend in the workshops which gives you an opportunity to spend time with the sponsors, learn new products, get a feeling for it and have the opportunity for feedback both ways. One of the advantages here is that faculty are always available. I encourage people to come up and talk, ask questions, give suggestions. Because at the end of the day, we have one goal, and that is patient improvement. And to all the things that we saw this afternoon on wounds, unbelievable. I hope they only work as much as we are putting forth that effort on a noncompliant population. The talk I’ve selected is electrical bone stimulation. Being a surgeon for 45 years, I think I’ve been beneath the skin a lot more than I’ve been dealing with the surface of the skin. And the challenges associated with bone are equally as difficult as that with skin. It’s just a different environment. I was happy to hear Bob talked about mesenchymal stem cells, and where they are, and what role they’re playing today. Bone marrow is one of the areas that mesenchymal stem cells are available. Many years ago, I started resurfacing the first metatarsal head using acellular dermis and cutting through the subchondral plate, denuding it to get to bone marrow or cancellous bone to allow for an ingrowth of mesenchymal stem cells into acellular dermis. With the amazing results or findings that hyaline cartilage was actually being developed into acellular dermis covering the head of a metatarsal. I am certainly excited about mesenchymal stem cells. Alright. Disclosures. Objectives, we’re going to know about bone when we’re done and some of the things that we can do to get through our objective goal, which is a nonunion, a difficult fracture, fill a void, do something that’s going to enhance the healing of a fracture, and certainly an immunocompromised patient that becomes that much more prevalent and important. We know a fracture heals in a certain amount of time. Can we improve that? Can we change that diabetic who may have just sustained a stress fracture on a lesser metatarsal, can’t put weight on the front of the foot, and it’s going to take a shortened length of time for them to be able to do it? Can we improve that timeframe? Can we shorten it? Bone stimulation is simple. It’s energy transmitted through bone to accelerate bone growth. Bone is a living tissue. I’ve always told my students that it’s not that bone that you remember in the cadaveric lab that we used to cut through, that was dense and dead.
Bone is a living tissue. It has the ability to heal. It has the cells to heal. Yet, why it doesn’t it? I’m a surgeon or I’d like to think I am. How many cases of delayed union have I seen on patients that I’ve performed perfect procedures? Because every surgical procedure I perform is perfect. Then utilize all the fixation devices that we see, and certainly when you walk through this exhibit hall, you’ll see all of the methods of fixation available. From internal to external, from wires to screws, to locking plates, everything that’s been thrown at us available in our surgical armamentarium to what? To try to get healing of bone. Not necessarily faster but get bone to heal. We recognized that stabilizing a site is important in the healing process. Angiogenesis is an important factor in healing. Some micromotion may be important in the healing process depending upon the type of union you’re trying to obtain or fracture type you’re trying to heal. Indications for bone stem are nonunions, delayed unions, fresh fractures, Charcot osteoarthropathy. We talked about direct current, capacitive coupling, inductive coupling, and ultrasound. Just as in the wound care arena, there are different materials to use. There are different modalities that are available to deal with the stimulation of bone. Historically, I’m not going to bore you with all of these. But certainly, you can read the literature by Yasuda and Becker and Bassick talking about first modern report of electric methods being used to heal nonunion, and actually by the medial malleolus. One of the areas in the country where a lot of the work was originally done was the University of Pennsylvania, which thankfully I’m on the staff at Penn Presbyterian Medical Center in Philadelphia. So a little bit of history always makes you feel a little better. We recognized there are electrical components in bone healing, Wolff’s law. Bone adapts to introduce stress. And stress-generated potentials create these small electric currents, which can change as bone starts to heal or adapt. Ability of crystals to produce a voltage when subjected to stress, that’s what happens with bone. We can actually measure it. Bone contains calcium phosphate crystals, making it subject to modification by introduction of voltage. It almost goes back to one of the talks where I heard about electrolyte imbalances in our diabetic population or in the patient population, calcium depletion. If calcium is critically important for bone modification healing, the calcium levels better be good. We can look at different parts of the bone and look at the concave or the convex surface of a bone and recognize that there’s electronegative and electropositive charges. We can get all kinds of fancy things to identify what happens when these structures are stressed. And we know the different stages of bone healing. I can remember probably 35, 40 years ago when AO/ASIF became an important component in the surgery we do. That instead of just using a K-wire, you need a screw across bone to create some compression. For some reason, the term compression has led to the development of how much can I push these two segments of bone together to get compression to be sure I get a union or a healing of the site. We don’t know that. Many times, you can get the opposite effect by crushing bone ends and actually create osteonecrosis. We get upset sometimes when we see the healing of an osteotomy and you say, “Oh my god, two to three weeks after the surgical procedure, I see a space at the site that I made that little sliver of a cut. I must be going on to a potential nonunion.” When recognizing, there’s osteoclastic activity that is taking away the necrotic bone that you created by using a saw blade when you cut bone or cutting through a nonunion site or resecting a nonunion site.
What we think we’ve done with remodeling, the body steps in and says, “I’m going to help you out some more,” by this osteoclastic activity which is going to be imperative before we’re going to get osteoblastic activity and ultimately osteogenesis and ultimate healing. I’m not going to bore you with different phases and when you can expect things to happen. But patients are pain in the butt sometimes. They are ones that broke a bone or they are the ones that have caused a nonunion, and the first question is, “Well, how long is it going to take to heal?” I’m going to have to be in a cast or Cam walker or in a mobilizer for 6 to 8 or 12 weeks. Lapidus procedures have become very much in vogue with bunion surgery. And now, we have got plates and screws and this thing is going to be completely stabilized. We just created an Eiffel Tower around the site for no motion to occur. And the reason? The patient wants to be able to walk faster. Does that imply that that bone is going to heal any quicker? Not necessarily. We’re just happy to know it’s stable and we’re going to let them walk. The patient is dictating our protocols, which I’ve never felt comfortable in allowing a patient to determine that. Nonunions unfortunately occur. What are the risks factors? Smoking. In this country, unbelievable. Philadelphia, they come in with packs of cigarettes attached to their crotches so they can smoke. Immunosuppressive drugs, diabetes, obesity, alcoholism, previous operations, hormone depletions, use of illicit drugs, age, nutrition. It goes on and on. The etiology of risk factors is almost everything we see everyday in our patient population. And we wonder why we sometimes have these potential complications. We look at smoker’s risk of fracture, in smokers is two to six times greater that it reduced bone density. Significantly higher number of nonunions. If I tell my patient to stop smoking, they laugh. Not going to happen. Pseudarthrosis, four times greater on nonsmokers. You eventually reach your point in time when you begin to see difficult fractures and difficult problems and recognize that these are potentially immunosuppressed. They’re going to continue to smoke and is there anything we can do to stimulate some bone production. Direct bone current stimulation increases amount of intracellular free calcium, and hydrogen peroxide generation at the cathode resulting an increased pH. It’s invasive. You’re implanting a battery and leads into the area. Direct current bone stimulation is a little bit different, making the device active for a period of 6 to 12 months. Here’s an example of a bone stimulator that I used which I implant. It’s got a cathode and it’s got the battery. And actually, they have dual leads that come from it. The advantage, I don’t have to worry about the patient using it. It’s in the bone. I’m going to show you that. Disadvantages, it has to come out if it’s annoying to the patient. At 6 to 12 months, it’s done. It’s used, it’s done its effectiveness. You may have painful prominence where the battery is inserted and I’ll show you some of that. On a more difficult case, here’s a Charcot. We’re doing everything we can to prepare these joint surfaces, replacing bone, using any other type of material that I’m going to use to fill the voids which is a dust disaster. You got to get necrotic bone out. Position everything in place with your hardware. Then I use a bone stimulator. Here’s an example of an ankle fusion. There’s a TTC rod and you could see the little wire because the elements of the cathode are actually in the joint surface. You’re getting compression as well as the actual implant that’s in place. Here’s an example of me putting in those dual leads into an ankle joint. You can use other materials, bone stimulating materials. This is an allomatrix which is placed into the joint, holds everything in place.
Here’s your external fixator on. Give yourself the compression. The beauty of external fix is that as you see areas of dissolution of bone, you can actually tighten the external fixer a little bit. If you get resistance, you know that you don’t need to do anymore. There’s a complication that I had on one of my patients. The battery pack was in place deep enough. It’s supposed to be between muscle and bone. She was a diabetic. She came in and she said, “I think I have a little problem on my leg.” I said, “You’re right about that.” We had to take that bone out, that battery pack out. Here’s an example of a dowel graft, a bone dowel that’s used. This is a medial malleolar fracture nonunion. You actually wrap the cathode around the dowel graft. Here it is in place, battery in place, and you go on to a beautiful union. Alright, we’re using the component. The dowel graft actually gives you tremendous compression by just placing that across the site and then the electrical stimulation goes beyond that. Capacitive coupling, ability of a device to store an electrical charge. We have two charge placed to generate a flow of current. One of the companies, OrthoPAC, was one of the devices that have been utilized where you just place these little pads by the site of nonunion or delayed union. Compliances of factor because this guy, he had to put on 24 hours a day. I don’t know any patient that is that compliant in my practice. My wife is not that compliant. Inductive coupling bone stem is another component with magnetic field using coils to deliver flow at the site of osseous interest and healing of the nonunion. We have combined magnetic field and pulsed electromagnetic field. Once again, we’re going to need time for these things to work. Here’s an example of pulsed electromagnetic fields. These usually run for 8 to 12 hours a day. The Physio-Stim light on the bottom is three hours a day. Now most of these devices have the ability to show you how many hours the patient has truly been using these bone stimulators. The patients are kind of smart. They could probably just turn it on and put it on around a broomstick and then go out and do what they want. They come into your office saying, “Let’s take a look. Oh, you’ve been doing it very well, 8 to 12 hours a day, but nothing’s happening.” Why is that? Then the wife or the husband, “I’ll have to tell you the truth, doctor. She hasn’t really been that compliant.” Alright, here’s another magnetic field through sinusoidal pattern. The advantages can be placed over a cast or a dressing with these pump systems. Disadvantage, as I say, is the compliance. Ultrasound, beautiful, I love it. Use of acoustic radiation above the limit of human hearing, by the way. They don’t feel anything, they don’t hear anything. And one of the beauties of ultrasound is you put it over the site for 20 minutes. I’m not dealing with 8 to 12 hours of compliance. How affective is this type of technology? Number of years ago, I fell down a flight of stairs coming out of a wedding at the Bellevue-Stratford Hotel and cracked three ribs. And went to the hospital Monday morning and said to my resident, wrap me up as much as you can with ACE bandages. I told the tech, get me X-rays of my ribs. Say, yeah, you got three fractures. I called the rep. I said, “Get me this bone stimulator.” I put one of these things over each of my ribs. I was miserable for three weeks. But if anybody here has ever sustained a rib fracture, not a happy camper. Three weeks I was playing golf. It became very apparent to me that 20 minutes was pretty damn effective. I couldn’t imagine wrapping a coil around my body with a pulsed electromagnetic component. Here is the ultrasound, 20 minutes a day. No effect on metallic implant presence. Doesn’t have any problem with it. It’s not based on thermal effects. And in a micro level ultrasound appears to stimulate the production of prostaglandin in E2. Here’s an example of a patient in a cast. You can actually window the cast and place these little devices on both sides of the foot. For 20 minutes a day it has to be activated.
That to me requires very little patient compliance. The effects of it have been dramatic. Alright. When we look at what happens with stimulation activation and upregulation of COX-2, it’s unbelievable the effect, alright? It affects inflammation soft callus, hard callus, and bone remodeling. Now the iatrogenic fibula fractures, I’ll hold off that last comment for a moment. Here’s an example of a fibular fracture. Do all the hardware you want in place. These are difficult areas. The vascular supply is limited. And they go on to a beautiful healing. Here is s patient with an agility ankle. Look at the fibular fracture on the left. We actually went in and put a fibular rod up the fibula to realign the position of the joint, a bone stem on the outside. And there you go on to a beautiful healing. Here’s other fracture. These are all with OsteoGen or the Exogen battery pack. There is over hardware. We were even doing studies about AVN of the talus. I think one of the most important things that we can look at is indications for these different bone stimulators. You just heard a talk about the fact that reimbursement is a major problem. Well, actually, Exogen is the only one that is indicated in fresh fractures. And it’s indicated in nonunions right off the bat. That to me makes a lot of sense in how I go about dealing with my complicated nonunions and non-heal fractures. I thank you for your time.