A Closer Look At Bone Stimulators For Charcot

By Michael S. Downey, DPM, FACFAS

What The Evidence Reveals About Bone Growth Stimulators

     Evidence-based medicine (EBM) has been defined as “the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients. The practice of evidence-based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research.”7 The evidence on the use of bone growth stimulators for the management of the Charcot foot is limited but some evidence does exist. No systematic reviews are available on this topic. Most of the papers have looked at the use of external bone growth stimulators as an adjunctive form of therapy in the acute Charcot foot.      In 1987, Bier and Estersohn provided possibly the earliest report on the use of bone growth stimulation for the management of the Charcot foot.8 They reported on three patients, who were each treated with cast and/or Unna boot immobilization, non-weightbearing and pulsed electromagnetic field bone growth stimulation. Using this combination of therapies, the authors reported clinical healing within three to four months.      In a smaller series in 1998, Strauss and Gonya provided two case reports involving the use of low-intensity ultrasound stimulation after Charcot reconstructive surgery.9 In both cases, the surgery involved ankle and subtalar joint arthrodesis with insertion of an intramedullary nail across both joints. Postoperatively, surgeons kept both patients non-weightbearing. Shortly after the surgery, surgeons initiated the LIUS mechanical bone growth stimulation. In one case, they noted a healed arthrodesis after 162 days. In the other case, they noted clinical and radiographic healing after 120 days. The authors concluded, “Adjunct low-intensity ultrasound should be considered in this population based upon its success in other parts of the skeleton and the early success presented here.”      In one of the better reports on this topic, Hanft, et. al., investigated the role of bone growth stimulation as an adjunct in managing the Charcot foot.10 The study included 31 patients. The first 21 subjects were randomized into the study or control groups. All 21 patients had diabetic neuropathy involving their lower extremities, accompanied by clinical and radiographic findings of stage 1 Charcot osteoarthropathy involving the foot and/or ankle.      The investigators immobilized all of the patients with a total contact cast or a fixed ankle walker with a contact molded multi-density thermoplastic insole. All of the patients also received compression stockings to help control the edema present. The researchers also uniformly instructed the patients to decrease their level of ambulation and weightbearing at 50 percent of what they were doing prior to treatment.      The study group received one additional modality, an Orthologic® combined magnetic field bone growth stimulator, which was not given to the control patients. This device was used for 30 minutes daily. After researchers studied and href="/files/photos/ pt1206charcot4.jpg" rel="lightbox">statistically evaluated the initial 21 patients, they enrolled 10 additional patients as study candidates, all of whom received bone growth stimulation.      Researchers examined several areas between the treatment group (21 cases) and the control group (10 cases) including:      • the duration of Charcot osteoarthropathy prior to the start of treatment;      • the patient age;      • the rate of consolidation of insulin-dependent patients with diabetes versus non-insulin dependent patients with diabetes in each group;      • obesity as a factor in consolidation time;      • total contact cast versus fixed walker as a factor in the consolidation time; and      • time to consolidation in patients receiving bone growth stimulation versus those not receiving bone growth stimulation.      The results of the study revealed that the mean time to consolidation for the treatment group was 11.0 weeks versus 23.8 weeks in the control group. This 12.8-week difference between the groups was statistically significant. With the exception of the application of the bone growth stimulation, all the other variables studied had no statistically significant effect on the time to consolidation.

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