Diabetic Foot and the Bedside Bone Biopsy

Florine Féron, MD; Jean-Philippe Kevorkian, MD; Ronan Roussel, MD


August 07, 2018

Editor's Note: The following is an edited, translated transcript of a conversation taped on June 24, 2018, during the 78th Scientific Sessions of the American Diabetes Association (ADA) in Orlando, Florida. Prof Ronan Roussel, endocrinologist and diabetologist in Paris, France, spoke with diabetologist Florine Féron and cardiologist Jean-Philippe Kevorkian, both from Hôpital Lariboisière, Paris, about diabetic foot ulcers, amputations, and bedside bone biopsy.

Roussel: Hello, and welcome to Medscape's set at the 2018 ADA conference in Orlando. Today our webcast is devoted to diabetic foot. It's not the most often reported complication of diabetes in abstracts or oral presentations at conferences, but there have been some interesting data at this year's ADA conference. Joining me to talk about a study they presented during an oral session on diabetic foot are diabetologist Florine Féron and cardiologist Jean-Philippe Kevorkian, both from the Department of Diabetology at Hôpital Lariboisière.

Epidemiology of Diabetic Foot in France

Roussel: Jean-Philippe, will you please give us an overview of diabetic foot? Is it still a problem in France?

Kevorkian: Yes, it is. Diabetic foot is a serious problem that impairs the lives of patients with diabetes. It's a major public health problem. We use this expression a lot, but it's a reality that is very costly to society. The occurrence of complications of diabetes—especially cardiovascular complications—has decreased considerably in the past 30 years as a result of improvements in therapeutic management and prevention, but ulcer and amputation rates (amputation being the main sequela of these lesions) have hardly changed.

Roussel: What percentage of ulcers lead to amputations? We can assume that some ulcers are managed at home. Amputations must be less common. What percentage of ulcers have an unfortunate outcome?

Kevorkian: About 30% of the hospitalized cases of diabetic foot ulcer result in amputation, whether limited or extensive.

Roussel: That's huge.

Kevorkian: Amputations are performed at all levels, from the toe or forefoot to the thigh, which is rare, but it's the major sequela. Obviously, this causes significant disability.

Roussel: Does this have an impact mainly in terms of the individual's quality of life or survival/mortality?

Kevorkian: Diabetic foot ulcers have two major sequelae. The first is functional. Diabetic foot ulcers impair mobility and everyday life, and require many more clinical visits, which is far from easy. They are also a major indicator of increased mortality, particularly cardiovascular mortality. We know that mortality in patients with diabetes is very closely associated with cardiovascular problems. In patients with diabetes who have foot ulcers, excess cardiovascular mortality is absolutely substantial.

Roussel: You used the word "indicator." Do you mean that it's a marker? Or is it because something happens in the foot and then the systemic inflammation that may or may not accompany it ends up creating an at-risk situation where the patient is at greater risk, for example, for an infarction or an episode of heart failure at that point compared with another? In other words, can something be done about this?

Kevorkian: Actually, it's both. The foot ulcer is an indicator of the severity of the patient's underlying condition. In the vast majority of cases, the patients are men aged 65-70 years. Most have had diabetes for a considerable amount of time, often more than 15 years, and nearly all of them have complications in the form of microangiopathy, macroangiopathy, neuropathy, nephropathy, and retinopathy, and also heart failure. All of these lead to foot ulcers, which will deteriorate during an eventual secondary infection. The diabetic foot ulcer reflects a deep impairment in the patient with diabetes, and all of these other areas can decompensate with a foot ulcer, especially during a secondary infection.

Roussel: The secondary infection will involve the ulcer, the skin, possibly the deeper tissues, and the bone. What percentage of ulcers are accompanied by osteitis?

Kevorkian: Roughly speaking, about half of infected ulcers are already complicated with a deep infection—that is, of the bone. Half—which is substantial! A severe, deep infection. A bone infection is serious. You have to go deep down to look for the microorganism responsible for it.

Bedside Bone Biopsy

Roussel: Florine, this brings us to your study.[1] Obtaining microbiological information is a principle that's in line with the recommendations and that everyone agrees with. However, putting it into practice can be problematic in terms of access to interventional radiologists or operating rooms for the purpose of performing biopsies. Your proposal is an alternative method that can be performed at the patient's bedside. Can you tell us how it works?

Féron: It all started for us in 2015. We had raised these problems regarding access and wanted to find an alternative solution, so we contacted the interventional radiology team at our hospital. They explained their protocol to us and we used it as a model. So, how does it work? On the day of the procedure, the patient, who doesn't need to be in a fasting state, signs a written consent form and is briefly premedicated.

Roussel: Premedication for pain?

Féron: For pain and anxiety. An hour later we can start the procedure, which generally takes an hour, including all of the preparations. During this time, we do a thorough disinfection, identical to what is done in the operating room. We then administer local anaesthesia. At this point the patient receives inhaled anaesthesia, and we can start the procedure.

We use the same trocar as the radiology team. It's a three-step procedure. First, we insert the instrument up to the bone. We never go through the ulcer; rather, we go through clean skin. We reach the bone, take our specimens, and then send everything within 3 hours in a dry tube to the bacteriology and anatomic pathology lab.

Roussel: Is there an initial localization or do you decide on the biopsy path clinically?

Féron: We do both. There is the clinical localization, with the anatomic landmarks on palpation. With radiologic landmarks, we can get an idea. In certain cases, especially for the metatarsals, we do a radiologic localization by sticking on a small metallic marker and sending the patient to radiology. With these images and visual localization, we can get size and precision markers to know where to insert the trocar.

Roussel: How large was your cohort, and what percentage of patients had a microbiologically negative biopsy result (no infection, no demonstrated osteitis)? What percentage had a microbiologically positive one?

Féron: In the study presented yesterday afternoon,[1] we had performed a bone biopsy in 33 patients. Today, we are at 80 patients because we have expanded a bit since. The overall ratio was 50/50—that is, 50% bone biopsies with a positive culture and 50% with a negative culture.

Roussel: Are these figures similar to those found in the literature for surgical or interventional radiologic approaches?

Féron: No. Actually, the figures found in the literature are closer to 30% negative bone biopsies. Therefore, we were higher than this figure. However, we increased our sample since September 2017 and reduced our figure. We are now at 38% negative bone biopsies, approaching 30%—thanks, no doubt, to expertise and refining of the indications.

Roussel: The biopsy findings should be negative because there are no microorganisms, not because we performed the biopsy outside of the infected area. Of the ulcers with negative biopsy results (negative because no microorganisms were found), what percentage will not heal and consequently require antibiotic therapy a few months later?

Féron: In our sample, it was marginal. What is very interesting is that in the end, the percentage that did not heal and the percentage that did in both the positive and negative bone biopsy groups were the same.

Roussel: That's rather odd.

Féron: What we really wanted to underscore yesterday afternoon was the validity of our bedside procedure in that the same number of ulcers healed successfully (in the end, the study lasted 14 months). The fact that the figure was the same in both groups strengthens this validity. Last, the outcomes of the 30% negative bone biopsies that did not heal were as follows: Two patients had a new bone biopsy a year later, of whom one had a positive result and experienced healing; two were treated surgically and subsequently healed; one patient died; and one who experienced a recurrence was subsequently healed.

Roussel: You mentioned a specimen intended for anatomic pathology. A paper[2] during the same session reported the added value, or the lack thereof, of the anatomic pathology examination. What's your opinion on this? Does this add to microbiological testing?

Féron: Here are our present results. We had 59 patients in whom an anatomic pathology examination was performed, and we feel that there was no added value. Among the microbiologically positive patients, the numbers of histologically positive and histologically negative patients were the same.

Roussel: Did any patients in the microbiologically negative group have microorganisms found during the anatomic pathology examination?

Féron: No. So far, we haven't caught any.

Roussel: So, in effect, this doesn't change patient classification in the end.

Féron: We feel that it doesn't. This is also what our colleague was saying in his oral presentation.

Roussel: One last question: How have your radiologist and surgeon colleagues reacted to your study? Do they see this as disloyal competition?

Féron: No, not at all. They have been very positive. As I said at the beginning, it was they who collaborated, and it was very positive. We clearly saw that the investment was not all that huge, and that today this procedure is being performed more and more. In the end, everyone is happy.

Roussel: Very good. Thank you very much, Florine. Thank you, Jean-Philippe. And thank you all for watching.


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