December 2013

Pages: 18 - 19

New Threatened Limb Classification System ‘Focuses On Whole Limb’

By Brian McCurdy, Senior Editor

A number of existing classification systems for threatened lower extremities gauge patients’ ischemia but can fail to consider factors such as tissue loss or the extent of infection. A new system, recently published online in the Journal of Vascular Surgery, proposes to classify at-risk limbs with a broader range of criteria.

   The new classification, dubbed WIfI, uses three criteria: wounds, ischemia and foot infection. The system grades each of the three factors on a scale of 0 to 3, signifying low risk, mild risk, moderate risk or severe risk. The authors note that this system combines previous classification systems that focus on diabetic foot ulcers with those that focus on pure ischemia. Researchers add that the new system is necessary because four decades of demographic shifts, particularly rising diabetes prevalence and rapidly expanding revascularization techniques, have made it more challenging to perform meaningful outcomes analysis using present classification systems for those with threatened limbs.

   The difference between the WIfI and existing systems is that the new classification does not specifically focus on the wound, the presence or absence of infection or the vascular classification, but instead takes all three factors into account, says co-author David G. Armstrong, DPM, MD, PhD. As he notes, the WIfI focuses on “not the hole in the foot but the whole limb.”

   As co-author Joseph L. Mills, Sr., MD, notes, since a threatened limb can occur in patients without diabetes, the system can classify the disease burden of any presenting patient, even those without diabetes. He compares the classification to the TNM cancer classification, which considers tumors, lymph nodes and metastasis to stage the burden of disease.

   As the study notes, both the Fontaine and Rutherford systems, which stratify lower extremity ischemia, lack detail and most systems that classify diabetic foot ulcers give the details of perfusion status but do not take gangrene into account. Dr. Mills agrees, adding that most diabetic foot ulcer systems use peripheral arterial disease (PAD) as a “yes or no” classifier, saying this can be a problem since this does not grade ischemia. In addition, he notes vascular language can ignore the presence of infection by focusing only on blood flow.

   “The Eurodiale study and other studies demonstrate clearly that the combination of PAD and infection triples amputation risk,” according to Dr. Mills, who is affiliated with the Southern Arizona Limb Salvage Alliance (SALSA) at the University of Arizona Health Sciences Center.

   Both authors compared the WIfI to the universal language of Esperanto or bringing together the SALSA concepts of “toe and flow.”

   “It allows us to speak together to get the same language and not speak in tongues,” says Dr. Armstrong, a Professor of Surgery and the Director of the SALSA program at the University of Arizona Health Sciences Center.

Can The Percutaneous Tenotomy Be Useful In Treating DFUs?

By Danielle Chicano, Editorial Associate

Patients with diabetic neuropathy who suffer from diabetic foot ulcers have a higher risk of foot amputations. A recent study in Foot and Ankle International says percutaneous tenotomy can be an effective treatment for diabetic foot ulcers.

   Researchers reviewed 160 percutaneous tenotomies for four indications: 103 tip-of-toe ulcers, 26 cock-up/dorsal ulcers, 21 kissing ulcers and 10 plantar metatarsal ulcers. Healing at four weeks was 98 percent, 96 percent, 81 percent and 0 percent respectively, according to the study.

   Nicholas Bevilacqua, DPM, FACFAS, utilizes percutaneous flexor tenotomy to treat distal tip ulcers in flexible hammertoes. He notes that digital deformities are known to increase pressures and are often associated with neuropathic ulcers.
“(Percutaneous flexor tenotomy) offers a less invasive approach and often affords the necessary intrinsic pressure reduction for ulcer healing,” adds Dr. Bevilacqua. “Outcomes are fairly predictable when patients are properly selected.”

   While the study concludes that percutaneous tenotomy is effective for treating toe ulcers, researchers deem the procedure ineffective for treating plantar metatarsal ulcers.

   Dr. Bevilacqua advises surgeons to consider performing an isolated metatarsal osteotomy or metatarsal head resection for an ulcer below a specific metatarsal head.

   “It is important to maintain a near normal metatarsal parabola to avoid transfer lesions under an adjacent metatarsal head,” explains Dr. Bevilacqua, who is in private practice at North Jersey Orthopaedic Specialists in Teaneck, N.J.

   Dr. Bevilacqua adds that surgeons should also consider an equinus deformity as a contributing factor to plantar metatarsal ulcers.

   “If this is present, a percutaneous Achilles tendon lengthening is an effective procedure to augment the healing of plantar forefoot ulcers,” explains Dr. Bevilacqua.

How Effective Is MRI In Diagnosing Osteomyelitis In Ischemic Feet?

By Brian McCurdy, Senior Editor

A recent study published in the Journal of Foot and Ankle Surgery notes that while magnetic resonance imaging (MRI) is effective in diagnosing osteomyelitis, the modality is less accurate in diagnosing the bone infection in the presence of ischemic ulcers.

   The study compared pre-op MRI results with histopathologic exams of 104 resected bones from 18 diabetic foot ulcers in 16 patients. The authors note that in eight neuropathic ulcers, 29 bones had an accurate diagnosis of osteomyelitis using MRI, even those bones with severe soft tissue infection. Of 75 bones in 10 ischemic ulcers, the study notes only seven bones evaluated by MRI after revascularization had an accurate diagnosis while the other 68 bones could not get an accurate MRI diagnosis. A histopathologic examination found all the bones to be infected through the bone cortex by the surrounding infected soft tissue, notes the study.

   Eric Lullove, DPM, notes that MRI is a very effective tool for delineating the margins and extent of osteolytic destruction of bone as a result of infection. He notes the imaging of the bone marrow contrast enhancement is very specific for osteomyelitis.

   “It is the gold standard in those patients who have normal renal function or slightly impaired renal function, or those patients free of pacemaker devices and recent orthopedic surgery,” says Dr. Lullove, a Fellow of the American College of Certified Wound Specialists, who is in private practice in Boca Raton and Delray Beach, Fla.

   However, Dr. Lullove notes the presence of ischemia does not affect MRI imaging, explaining that the MR spin rates the water in the body, not the blood flow. If one is looking at MR angiography, he says ischemia would be relevant but not as relevant in MRI for osteomyelitis.

   Dr. Lullove notes a computed tomography (CT) scan is not as specific as MRI for osteomyelitis and plain film radiography will show osteolytic processes, but well after the infection process is beyond 14 to 21 days from the onset. He says one can utilize ultrasonography to see periosteal reactions and violations of the cortex in areas where one can use sonographic imaging effectively.

   Although some studies recommend the routine use of gadolinium, Dr. Lullove notes that others suggest that it is unnecessary. "There is no convincing evidence that contrast improves the diagnostic accuracy for osteomyelitis, but it is clear that its use improves the evaluation of soft tissue pathology as it helps to demonstrate abscesses and sinus tracts more easily. The use of contrast may also allow differentiation of viable from non-viable bone or soft tissue," he notes.

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