July 2012

Updated IDSA Guidelines On DFIs Emphasize Appropriate Antibiotic Use

By Brian McCurdy, Senior Editor

The Infectious Diseases Society of America (IDSA) has released its latest guidelines for diabetic foot infections, updating the recommendations from 2004.

   The guidelines primarily urge clinicians to determine if a diabetic foot wound is clinically infected and to avoid prescribing antibiotics for the approximately 50 percent of wounds that are clinically uninfected, according to Benjamin Lipsky, MD, FIDSA, the lead author of the IDSA guidelines.

   Dr. Lipsky notes it is sufficient to use narrow-spectrum therapy aimed only at staphylococci and streptococci for most acute mild or moderate diabetic foot infections in patients who have not recently received antibiotics. He says one can usually reserve broader spectrum empiric therapy for severe infections or patients who have failed previous antibiotic therapy.

   Dr. Lipsky adds that the duration of antibiotic therapy rarely needs to last for more than one or two weeks for most soft tissue infections although it may need to be longer for unresected osteomyelitis.

   “The key issue is we have to continue to start broad and get more narrow” with antibiotic coverage, notes David G. Armstrong, DPM, PhD, MD, a co-author of the guidelines. “However … I think we’re going to be moving from Louis Pasteur-based microbiology to CSI-based microbiology where we’re moving away from just plating everything on a petri dish toward actual molecular diagnosis.”

   Such molecular diagnosis will over the coming years speed up assessments but Dr. Armstrong says this will also most likely show a “massive difference” in the kinds of bacteria and the amount of bacteria clinicians see in diabetic foot infections. Clinicians will be looking at the whole microbiome rather than the individual bacteria, notes Dr. Armstrong, a Professor of Surgery at the University of Arizona College of Medicine and the Director of the Southern Arizona Limb Salvage Alliance.

   “Whether this difference on the diagnostic side makes a massive difference clinically remains to be seen but it is exciting nonetheless,” adds Dr. Armstrong.

   The main changes to the guidelines since 2004 entailed the use of a new format of asking key questions, answering them and providing the evidence base for the recommendations, notes Dr. Lipsky, a Professor of Medicine at the University of Washington and the Director of the Primary Care Clinic at the Veterans Affairs Puget Sound in Washington. He also points out the use of the GRADE system to grade the quality and strength of the recommendations.

   Although most of the basic principles in the 2012 and 2004 guidelines are the same, Dr. Lipsky notes that the authors added 345 references (mostly published since the last guidelines). He says they provide “far more evidence” for the recommendations and information on newly published papers on antibiotic therapy for diabetic foot infections. Dr. Armstrong also praises the abundance of research in the updated guidelines, noting that the last 10 years have seen a greater than 80 percent increase in the number of studies on the diabetic foot.

   Dr. Armstrong notes that the implementation of the diabetic foot infection guidelines may be able to save costs in hospitals. “I think (these guidelines will have) a real economic impact as well as a pragmatic and scientific impact for our patients,” notes Dr. Armstrong.

Poll: Most Hammertoe Implant Complications Occur In Second Toe

By Danielle Chicano

In a recent Podiatry Today online poll, 57 percent of the respondents (137 votes) agree that most complications with hammertoe implants occur in the second toe (see http://tinyurl.com/72nftjf ). Of the remaining 239 DPMs polled, 16 percent (38 votes) see the most implant complications in the great toe; 11 percent (27 votes) see the most in the fourth toe; 11 percent (26 votes) see most complications in the fifth toe; and the remaining 5 percent (11 votes) see the most complications in the third toe.

   Babak Baravarian, DPM, and Don Green, DPM, both find the results of the poll to be consistent with what they see in practice, agreeing that most complications occur in the second toe.

   As Dr. Baravarian explains, some surgeons do not fuse the second toe and it may drift or shift. Another main reason for complications is that second metatarsophalangeal joint (MPJ) plantar plate tears go undiagnosed and there is a failure of implant positioning due to MPJ insufficiency, according to Dr. Baravarian, an Assistant Clinical Professor at the UCLA School of Medicine.

   The fact that the second toe is most prone to hammertoe makes that toe most prone to implant complications, says Dr. Green, a Fellow of the American College of Foot and Ankle Surgeons and faculty member of the Podiatry Institute.

   Dr. Green notes the most common hammertoe complications he sees are floating toe (lack of purchase) or hammertoe recurrences. In such cases, he has found arthrodesis of the proximal interphalangeal joint to be helpful rather than performing arthroplasty.

   Surgeons should ensure there is no tear of either the collateral ligament or the plantar plate prior to performing hammertoe surgery, according to Dr. Baravarian, the Director of the University Foot and Ankle Institute in various locations in California. He also advises surgeons to “align bone on bone ends for solid fusion” and to avoid using implants in soft bone.

   In order to avoid unsuccessful outcomes, Dr. Green says podiatric surgeons should consider prior to hammertoe surgery whether they will be able to neutralize the deforming forces upon the affected toe intraoperatively or postoperatively.

   Dr. Green suggests splinting as a proactive tip to avoid potential complications. Specifically, he notes the use of post-op splinting with Betadine soaked gauze (a Betadine cast) or temporary K-wire splinting. Alternately, Dr. Green says one may opt for splinting over a longer period of time with modalities such as Bio Skin (Cropper Medical), anti-dorsiflexion pads, Coban “buddy splinting” or a Budin splint.

Could Run-Off Resistance On MRA Change The Way Physicians Diagnose PAD?

By Brian McCurdy, Senior Editor

A recent study in the European Journal of Radiology finds that assessing run-off resistance on magnetic resonance angiography (MRA) may be effective as a scoring system in patients with peripheral arterial disease (PAD).

   The authors performed contrast-enhanced MRA in 321 patients with PAD using a 1.5-T magnetic resonance scanner with a moving bed technique. Researchers detected a significant negative correlation between the run-off resistance and resting ankle brachial index (ABI) in each patient. The study concluded that the run-off resistance system correlates better with ABI than previously published systems and could be a reporting system for MRA evaluation.

   Magnetic resonance angiography “is absolutely the most sensitive of all imaging studies for diagnosing PAD,” notes Kazu Suzuki, DPM, CWS. “At the same time, it is the most expensive imaging study of all. It’s a trade-off.”

   The ABI is still one of the most cost-effective diagnostic tests for PAD and Dr. Suzuki says the test only needs a skilled technician or physician, a blood pressure cuff and a handheld Doppler device. However, he notes that ABI can easily fail to detect PAD in patients with diabetes or those on dialysis due to calcified leg arteries. Accordingly, Dr. Suzuki uses skin perfusion pressure and pulse volume recordings for PAD testing in his wound care center.

   Dr. Suzuki believes the run-off resistance is “an interesting and novel angle” to test for and categorize the severity of PAD. He would like to see further research comparing run-off resistance scores of various therapies of PAD at different points during treatment to the limb salvage rates of such therapies respectively. Dr. Suzuki says the run-off resistance scores may provide more ideas on why one should choose a certain therapy over another, given the severity and morphology of the arterial occlusion and stenosis in lower extremities.

   “Right now, the selection of PAD therapy (intervention) is based entirely on the clinician’s discretion, meaning it is ‘more art than science’ to some level. We can potentially bring out more ‘science’ to this equation with more qualitative hemodynamic studies such as run-off resistance,” says Dr. Suzuki, the Medical Director of the Tower Wound Care Center at the Cedars-Sinai Medical Towers in Los Angeles.

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