November 2010

Study Assesses Long-Term Results Of Radiofrequency Nerve Ablation

By Brian McCurdy, Senior Editor

After patients have failed conservative treatment for plantar fasciitis, radiofrequency nerve ablation (RFNA) may be an effective option. A recent study in Foot and Ankle Specialist notes that patients have been pain free for up to 12 years after RFNA.

   The retrospective review focused on 82 patients who had undergone radiofrequency nerve ablation for neurogenic heel pain. Follow-up occurred at five, 10 and 12 years, and 89 percent of patients experienced no recurrent pain at these follow-up points, according to the study.

   In his use of RFNA, Adam Landsman, DPM, PhD, has found results similar to that of the study but notes that his longest follow-up is five years. He has found “nearly complete resolution of symptoms” in about 80 percent of patients with no recurrence of symptoms. Some patients experience some improvement right away but he notes that it takes four to 12 weeks after the procedure to appreciate the full benefits. Dr. Landsman notes that last year he published a randomized, prospective, blinded study in the Journal of Foot and Ankle Surgery, which “clearly supports” the benefits of this procedure.

   Most of Dr. Landsman’s RFNA patients have previously failed conservative modalities and some surgical procedures before undergoing RFNA.

    “I think that the real question here is, ‘Why do we wait so long to do the procedure?’ There are few potential complications and the treatment works rapidly and lasts a long time,” says Dr. Landsman, an Assistant Professor of Surgery at Harvard Medical School in Cambridge, Mass. “It does not cause any biomechanical problems. In the worst case, it may not work but it does not seem to ever increase pain.”

   Stephen Barrett, DPM, cites the importance of the authors’ conclusion that there is a high association with plantar fasciosis and nerve entrapment of the medial calcaneal nerve(s). Furthermore, he says it is critical that the study authors established a neural etiology in all of their patients.

    “This is a big difference that has been obfuscated by nearly all discussions of heel pain. The most frequent etiology in heel pain is plantar fasciopathy (a true musculoskeletal condition). However, there are many cases of multiple etiology heel pain and many cases in which there is a diagnosis of plantar fasciopathy that is in reality solely neurogenic,” points out Dr. Barrett, an Adjunct Professor at the Arizona Podiatric Medical Program at Midwestern University College of Health Sciences.

   Although he has previously criticized nerve ablation for plantar fasciopathy, Dr. Barrett says the modality does have a role for patients in whom the entrapment of the medial calcaneal nerve is the primary pain generator. He does caution that RFNA causes a peripheral nerve injury and serious complications can develop with any such modality.

Should You Use A General Anesthetic With RFNA?

Dr. Landsman was surprised the study authors used a general anesthetic as patient feedback is a critical part of correct probe placement. For RFNA, he uses the NeuroTherm NT250 (NeuroTherm) and the device’s built-in sensory stimulator. He asks the patient for feedback to ensure he has located the proper nerve.

   Dr. Landsman was also surprised about the study’s finding of reduced impedance in the presence of local anesthetic. He says the NeuroTherm device allows the measurement of impedance. The next time Dr. Landsman performs this procedure, he notes that will locate the nerve, measure impedance, infiltrate the area with local anesthetic and measure the impedance again.

    “I have always done this procedure with local infiltration and have had great success so this may even give me greater improvement,” says Dr. Landsman.

Is Probe To Bone The Best Test For Osteomyelitis In DFUs?

By Brian McCurdy, Senior Editor

Given that osteomyelitis can be a serious complication of diabetic foot wounds, having an accurate diagnostic tool is invaluable. A recent study in Diabetes Care concludes that the probe to bone test is the best diagnostic test for osteomyelitis in these wounds, particularly neuropathic wounds.

   The study’s sample size was 132 lower extremity diabetic wounds with clinical suspicion of infection. The authors noted that the diagnosis of ulcer infection was via clinical signs of infection and culture. Of 132 lesions, researchers diagnosed 105 as osteomyelitis.

   In the study, the probe to bone test showed the best diagnostic results with an efficiency of 94 percent, sensitivity of 98 percent and specificity of 78 percent. In addition, the probe to bone had a positive predictive value of 95 percent, according to the study.

   Although probe to bone can be effective in detecting osteomyelitis, John S. Steinberg, DPM, emphasizes the “common sense” usage of the test. He cites the importance of determining whether the wound is chronic or acute, and determining the time the wound has been exposed. Dr. Steinberg says the wound can be dirty due to long exposure.

   The probe to bone test is most effective in patients with longstanding, non-healing diabetic wounds, according to Dr. Steinberg, an Associate Professor in the Department of Plastic Surgery at the Georgetown University School of Medicine in Washington, D.C. He adds that the test is least effective in surgically exposed wounds, in which the surgeon knows the bone is clean but the wound is not closed.

   For further reading, see “Point-Counterpoint: Probe To Bone: Is It The Best Test For Osteomyelitis?” in the January 2007 issue of Podiatry Today.

Can Neurostimulation Aid Recovery After Ankle Fracture Surgery?

By Brian McCurdy, Senior Editor

A recent study in the Journal of Foot and Ankle Surgery notes that non-invasive neurostimulation can provide improved pain relief following surgery for ankle fractures.

   The study consisted of 60 patients who had undergone operative reduction and internal fixation of bimalleolar AO type B2 ankle fractures with comminution. One study group underwent post-op treatment with the InterX® (Neuro Resource Group), a noninvasive interactive neurostimulation device, while the other study group received a sham treatment.

   Following the study, authors note that pain decreased by 28 percent in the neurostimulation treatment group in comparison to a 3 percent decrease in the sham group as measured by the Visual Analog Scale. The range of motion had improved by 50 percent in the treatment group but stayed the same in the control group, according to the study. In addition, authors noted decreased edema in the neurostimulation group.

   For patients with ankle fractures, assuming they have stable fixation of the fracture, Christopher Hyer, DPM, attempts to minimize the muscle loss, arthrofibrosis and decompensation that result from a long period of casting or immobilization. To that end, his patients will wear a removable boot walker as early as possible so they can begin range of motion exercises. Dr. Hyer emphasizes that surgeons must initially balance this approach with concerns of stability, healing of the fracture and protection of the internal fixation.

   One can use the noninvasive muscle stimulator immediately after the surgical procedure, according to Dr. Hyer, a Fellow of the American College of Foot and Ankle Surgeons. He notes one can even use the stimulator with the patient in the posterior splint or cast as this keeps the motor end plates of the muscles alive and active.

   In his practice, Dr. Hyer has found that patients experience “far less” postoperative pain and swelling, and maintain “much more” muscle mass and tone during the immobilization period. As he notes, that seems to translate to a quicker return to activities and better overall outcome.

   As for adverse effects of neurostimulation, Dr. Hyer has only seen possible occasional contact dermatitis from the adhesive patch of the stimulator contact.

   “Some may worry about the muscle contractions possibly weakening their fracture repair but I feel confident that if good surgical technique and fracture repair principles are employed, light muscle contraction will not compromise the internal fixation construct,” explains Dr. Hyer.

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