Can Bracing Have An Impact For The Charcot Foot?

Although surgical reconstruction can be effective for patients with Charcot, not every patient is an appropriate candidate for surgery. Accordingly, this author explores the potential of employing various forms of bracing, including ankle foot orthoses and patellar tendon bracing, in patients with Charcot foot.

Many years ago, I was an early advocate for surgical reconstruction of Charcot foot deformities as a means of reducing the risk for ulceration and possible amputation of the lower extremity. It would appear that surgeons have widely employed Charcot reconstruction and many favor it for this condition.

   However, each physician will at some point face patients with Charcot deformities who might otherwise benefit from surgery but physiologically may prove to be poorly suited to this type of intervention. There may be many reasons such patients are not suited to reconstruction. For patients with Charcot deformity, there is often no shortage of medical comorbidities that may create hazards, whether they occur during the procedure or postoperatively. In some patients with Charcot foot deformity, braces may prove to be the mechanism through which patients maintain some level of mobility without surgical intervention despite possessing significant deformity.

   Over 20 years ago, I watched as Gary Bauer, DPM, delivered a lecture on salvage of the limb after severe lower extremity infections. Many of the patients in his presentation had received multiple ray resections for infection yet functioned reasonably well despite the fact that they were left with a significantly compromised foot or a foot that many surgeons could consider to be beyond salvage and requiring proximal amputations. The key element between success and failure appeared to be the fact that Bauer employed postoperative bracing whereas to that point, I had not done so.

   It was not long thereafter before patients with more tenuous medical conditions began to present to our practice with significant Charcot foot deformities. The question was: how could we best treat these patients and maintain some degree of function without surgery?

   The answer appeared to be bracing. Many of us received little if any formal training relative to the use of braces, their indications and the available options. However, I found that many patients were able to achieve enhanced function and mobility without surgery. Success bred confidence with this technique. Accordingly, I would like to share a general philosophy I have employed relative to the use of braces in this patient population.

Essential Considerations Before Proceeding With Bracing For Charcot

There are a number of factors that one must consider in assessing a patient for potential conservative management of the Charcot foot. First, is the foot quiescent? If not, then the patient will need to be immobile and non-weightbearing until the active inflammatory process has resolved.

   The next issue involves the overall stability of the foot. One may encounter three potential scenarios: a stable foot; a foot that retains mobility but has a fairly stable end range of motion; or a foot that is completely unstable. The latter foot type may prove very difficult to control with bracing but patients with a stable foot or those with stable end range of motion may be reasonable candidates for a conservative approach with braces.

   The primary plane of deformity may also influence the success or failure that one may achieve with bracing. Typically, sagittal plane deformities, if stable, may respond to bracing more readily than transverse plane deviations or a combination of the two. Oftentimes, a more limited surgical intervention, such as an exostectomy, may prove helpful in eliminating a plantar prominence and rendering the patient more amenable to bracing, and with less risk than a full reconstructive surgery.

   There are three primary forces that may act to disrupt a neuropathic foot. These forces are shearing, bending and vertical load. One may adequately control shearing forces with accommodative innersoles or orthotics. Studies in normal feet have demonstrated that clinicians can also neutralize shearing forces with an ankle foot orthosis (AFO).1

   In my opinion, the most destructive force in many neuropathic feet is an excessive bending force, typically mitigated by ankle equinus and the tight Achilles tendon. This is a key factor in the development of the initial collapse and will also serve to render the patient susceptible to subsequent problems even after the initial fracture/dislocation has healed. In some instances, one may employ a tendo-Achilles lengthening via local anesthesia even if the patient is not a candidate for more aggressive intervention. Post-op bracing may help protect the foot. Conservative options for neutralizing the effects of ankle equinus include elevation of the heel of the shoe. Typically, a 1-inch elevation of the heel over the sole of the shoe is sufficient.

Pertinent Insights On Bracing Options

In addition to the cited literature below, the options and preferences I discuss below are based on my experience with these devices. There are many different bracing options available and each physician may find that different options work effectively in his or her own experience.

   Ankle foot orthosis. An AFO is a very simple means of reducing stress to the foot and ankle with weightbearing. Landsman and Sage found success in healing recalcitrant ulcers in neuropathic patients using an AFO.2 Furthermore, their study showed a 72 to 90 percent reduction in peak pressures at the ulcer sites in comparison to the use of shoes with Plastazote liners alone. Researchers have also shown that AFO devices limit mobility in all three planes within the rearfoot and midfoot in normal patients.1 In a study of 20 asymptomatic patients, Kitaoka and colleagues found that the AFO limited sagittal and coronal plane ankle-hindfoot motion. At the midfoot, they noted the AFO limited transverse motion. One would presume a similar response would occur in Charcot patients.

   An AFO is very light, fairly inconspicuous with shoes and slacks, and many patients accept it fairly well. The main problem with the device is that many Charcot patients have deformity within the foot that requires accommodation with an orthotic or a deep Plastazote liner to prevent local irritation and ulceration. Adequate protection of the deformed foot is oftentimes difficult to achieve with the hard plastic of the AFO. Furthermore, accommodation for ankle equinus more readily occurs via other measures in comparison to an AFO. Therefore, I have found that many patients with Charcot deformity simply have conditions for which an AFO is not the optimal device.

   Double upright brace. The double upright brace functions similarly to an AFO but one affixes the brace to the heel of the shoe. Accordingly, one may employ sufficient protective measures within the shoe for a deformed foot to accommodate prominences.

   In addition, when one combines a double upright brace with a 1-inch heel raise and a rocker sole, it may help to reduce bending forces within the foot during gait. Typically, the articulation of the brace is either locked at neutral or it only allows plantarflexory motion, stopping dorsiflexion at neutral. In this manner, the brace and shoe disperse much of the mechanical stress that may otherwise disrupt the foot with weightbearing. This has been the most common form of bracing that I have employed for many years.

   Patellar tendon brace. The patellar tendon brace represents a more restrictive type of device and is also more difficult to fit and fashion for the patient. The brace fits around the knee and directs vertical weightbearing forces through the knee as opposed to the foot.

   One study has shown that a well fitted patellar tendon brace can reduce vertical load to the rearfoot by approximately 30 percent but the offloading effect is diminished as one proceeds from proximal to distal.3 Specifically, Saltzman and colleagues found that patellar tendon braces reduced load transmission to the hindfoot but not to the midfoot or forefoot.

   Patient acceptance of the patellar tendon brace is not as great as it is with the AFO or double upright brace due to the difficulty in application of the device and the overall bulk of the brace. In addition, patients with chronic knee arthritis or other problems at this level may not tolerate this type of device. However, this type of brace is helpful in reducing risk in patients with ankle or rearfoot deformity in which the direct effects of vertical load may be more pronounced. One may also combine patellar tendon braces with depth oxford or molded shoes with the necessary lining materials, or orthotics to protect the foot more effectively.

   Charcot restraint orthotic walker (CROW). The CROW devices appear to be in use with increased frequency in patients with Charcot deformity. Casts appear to provide the greatest limitation of motion in the ankle and foot in comparison to other devices. Additionally, it would appear that, in theory, a CROW device would more closely reproduce the fit and function of a cast.4 Therefore, the CROW may be a very effective type of bracing modality. One can incorporate a rocker sole to facilitate weightbearing. However, there is great deal of bulk with this device and at times, I have experienced problems in finding prosthetists who can fashion a device that provides a good fit.

Case Studies In Using Braces For Charcot

Figure 1 shows the foot of a neuropathic patient with Charcot deformity involving both the transverse and sagittal planes, and following excision of the fifth metatarsal for osteomyelitis. Postoperatively, I placed the patient into a double upright brace with a locked ankle, a 1-inch heel raise and a rocker sole. She functioned with this device with no recurrent ulceration and no additional Charcot episodes for several years prior to her death.

   Figure 3 shows the foot of another neuropathic patient who presented with acute Charcot involvement of the rearfoot. She wore a cast until the acute phase resolved and in spite of a significant loss of bone, there was sufficient fibrosis that developed to provide some stability. Due to the rearfoot involvement, she wore a patellar tendon brace to reduce loading to the rearfoot with success.

   Figure 5 (right) shows a quiescent sagittal plane Charcot deformity and good stability. The patient wore a double upright brace. Four years later, there had been no progression of deformity and the osseous structures had further consolidated in the midfoot.

When There Is Bilateral Charcot Deformity

What about patients with bilateral Charcot deformity? I have employed bracing in this scenario via one of two means depending upon the severity of deformity and other patient specific concerns. If one employs more traditional bracing, then use a double upright brace for the foot deemed most at risk and a single lateral upright on the contralateral limb. Patients with a double upright brace on each limb may have a higher risk of falling if the medial struts impact each other with weightbearing.

   However, one may employ two double upright braces if the deformity is such that the medial brace can be closely aligned with the medial ankle and leg. Alternatively, one could use a CROW walker on each side.

In Conclusion

Bracing can provide a viable option to improve function and reduce risk in many patients with Charcot deformity. If this modality has not been an integral part of your practice, you might consider calling a local prosthetist and meeting him or her to exchange thoughts and institute a referral relationship.

   Dr. Banks is in private practice at Village Podiatry Centers in Tucker, Ga. He is board certified in Foot and Ankle Surgery, and is a Diplomate of the American Board of Podiatric Surgery. He is a faculty member of the Podiatry Institute and a Fellow of the American College of Foot and Ankle Surgeons. Dr. Banks was the chief editor of the third edition of McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery.

References
1. Kitaoka HB, Crevoisier XM, Harbst K, Hansen D, Kotajarvi B, Kaufman K. The effect of custom-made braces for the ankle and hindfoot on ankle and foot kinematics and ground reaction forces. Arch Phys Med Rehabil. 2006; 87(1):130-135.
2. Landsman AS, Sage R. Off-loading neuropathic wounds associated with diabetes using an ankle-foot orthosis. J Am Podiatr Med Assoc. 1987; 87(8):349-57.
3. Saltzman CL, Johnson KA, Goldstein RH, Donnelly RE. The patellar tendon-bearing brace as treatment for neurotrophic arthropathy: a dynamic force monitoring study. Foot Ankle. 1992; 13(1):14-31.
4. Raikin SM, Parks GBG, Noll KH, Schon LC. Biomechanical evaluation of the ability of casts and braces to immobilize the ankle and hindfoot. Foot Ankle Int. 2001; 22(3):214-219.

   For further reading, see “A Guide To Bracing For Charcot” in the June 2004 issue of Podiatry Today, “Point-Counterpoint: Active Charcot: Should You Proceed With Surgery?” in the March 2005 issue, “Emerging Evidence On Treatment Of The Diabetic Charcot Foot” in the March 2012 issue, “Reassessing The Impact Of Diabetic Footwear” in the March 2004 issue or “A Closer Look At Fixation Options For The Charcot Foot” in the November 2005 issue.