A Closer Look At Bone Stimulators For Charcot
- Volume 19 - Issue 12 - December 2006
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In 1993, Cohen, et. al., were the first to report the use of an implantable direct current bone growth stimulation as an adjunct in the surgical repair of a nonunion following Charcot midfoot reconstructive surgery.12 More recently, Wang, et. al., described their success using pulsed electromagnetic field bone stimulation following surgical reconstruction of the Charcot foot and ankle with external fixation.13 This is one of the only papers looking at the use of electrical bone growth stimulation following Charcot foot reconstructive surgery.
The authors performed reconstructions in 28 patients with Charcot deformities of mainly Lisfranc’s joint or the ankle joint. In their series, the researchers performed an open or percutaneous tendo-Achilles lengthening, arthrodesis of the involved joints with the use of a hybrid or ring-to-ring external fixator, and application of PEMF external bone growth stimulation immediately postoperatively. The authors noted radiographic consolidation of the correction at a mean of 3.1 months. While they reported consistently good results in their series, the study authors recognized that a larger series would be necessary to support their positive results further.
Current Recommendations: What You Should Know
What is the bottom line? Current evidence supports the use of electrical or mechanical bone growth stimulation in the acute stages of Charcot foot, but the evidence is still limited. All of the papers report the use of electrical or mechanical bone growth stimulation in the acute stages of Charcot osteoarthropathy or Eichenholtz stage 1 or 2 (i.e. stage of development or early stage of coalescence). There is no current evidence to support the use of bone growth stimulation in the chronic Charcot foot deformity or Eichenholtz stage 3.
Out of the currently available bone growth stimulation devices, the CMF and PEMF stimulators have been the most extensively studied in the Charcot foot, and appear to be the most validated of the electrical bone growth stimulation devices. There are case reports of the use of direct current (DC) bone growth stimulation and mechanical bone growth stimulation (i.e. LIUS) but nothing further is currently available. There are currently no reports regarding the use of the capacitive coupling bone growth stimulation device. Future studies are needed that focus on prospective randomized controlled trials so meta-analyses of these trials can increase the effective study population and result in meaningful, clinically useful guidelines.14
In all situations, the clinician should first clinically and radiographically evaluate the patient with suspected Charcot osteoarthropathy and determine whether a bone growth stimulation device is indicated, appropriate and potentially helpful. One should not expect a bone growth stimulator to correct a malunion nor should clinicians use it as a substitute for immobilization and offloading. In my opinion, once you have determined that a bone growth stimulator is desirable in the management of a patient, the type of stimulator you use is less important.
The non-invasive devices all have different times of application. Often device representatives, in order to promote their device over another device, advertise these application times. Clinicians should recognize that the time of application is highly variable and it does not imply that one device is better than another. With PEMF stimulation, CMF stimulation and LIUS stimulation, generally shorter times have been advocated. Similarly, longer usage times with these devices have shown continued effectiveness but to a lesser degree. DC stimulation and CC stimulation are advocated for use 24 hours a day. These devices have shown improved efficacy with progressively longer periods of use.2