A Closer Look At Fixation Options For The Charcot Foot
When Jean-Marie Charcot described the entity that bears his name in 1868, little did he know the controversies he would create. Charcot joint disease (or Charcot neuroarthropathy) has been one of the most misdiagnosed conditions in patients with diabetes mellitus. Patients with this entity have been misdiagnosed and consequently mistreated for osteomyelitis, cellulitis, tendonitis and gout. Over the years, various controversial questions have been posed about the treatment of Charcot neuroarthropathy. These questions range from what type of diagnostic tests one should order to what type of surgical intervention is indicated for Charcot joint disease. The controversy continues to this day. In recent years, surgical reconstruction of the Charcot foot and ankle has become more aggressive. Less “lump and bump” surgery is advocated and more surgeons are performing primary fusion procedures. Fixation devices have run the gamut from simple staples to large diameter screws, intramedullary rods and complex external fixators. Are these passing fancies or are these devices the saviors of the diabetic foot their proponents claim them to be? Unfortunately, there are few studies that will objectively answer these questions. This article may in fact raise more questions than it answers. Hopefully, it will provide some rationale for the use of fixation devices.
When Surgery Is Necessary
When clinicians diagnose Charcot neuroarthropathy early and treat it appropriately, the majority of patients do well with conservative treatment. They will be left with feet that are free of ulcerations and have minimal residual deformities. Employing protective shoes or braces can help prevent the severe consequences of the neglected or misdiagnosed Charcot joint. Unfortunately, a large number of patients will present with foot deformities, instability or ulcerations as their initial symptoms. For those patients, one can consider a variety of surgical options, which range from simple exostectomies to exostectomies with rotational flaps or even free tissue transfers. In more severe deformities with significant instability, primary fusion may be the procedure of choice. The level of the deformity will dictate the level of fusion whether it is a midfoot, triple or ankle arthrodesis. Today, the use of plates, screws and intramedullary nails has become standard practice in these complex fusions. They provide more solid fixation with improved outcomes. Cannulated screws facilitate relatively simple insertion. In recent years, the use of external fixation has become more commonplace. These devices have undergone significant changes since their introduction into surgical practice in the late 1800s. Circular frames with skinny wires have replaced the unirail with Schanz pin systems for the most part. Additionally, these circular frames can either be static or dynamic depending on the goals of the surgeon. Internal and external fixation play key roles in reconstructive surgery of the Charcot foot and ankle. Understanding the indications for these modalities will allow for more successful outcomes and fewer complications.
What Advantages Does Internal Fixation Offer?
Internal fixation is best suited for subluxed joints with minimal bony destruction. Good bone quality and substance are essential for screw purchase. It is also preferable to place screws where an intact soft tissue envelope exists. This implies that whenever possible, it is best to perform surgery when plantar ulcerations are healed. Also be aware that the presence of unresectable osteomyelitis is a contraindication when it comes to using internal fixation. Nevertheless, internal fixation maintains clear advantages over external fixation in that it facilitates compression across joints and buried fixation devices with a single operative procedure.
What You Should Know About Circular Frames And External Fixation
Circular frames have gained increased popularity in podiatric surgery due to their ability to bridge the gap between successful internal fixation and amputation. Frames are particularly useful in cases in which internal fixation is contraindicated and the patient is facing a major limb amputation. As with any new technology, a period of overutilization has been followed by a more rational approach based on clinical experience and published reports. This is the case in podiatric surgery today. While there are few evidence-based reports on the use of external fixation in treating Charcot joint disease, anecdotal reports and personal communications are beginning to shape the indications for circular frames. The primary utility of external fixation is the ability to insert fixation wires proximal and distal to potentially infected joints or severely destroyed joints. This facilitates stability while the joints consolidate. Surgeons can also apply external fixation devices in the presence of open ulcerations. In fact, the stability they lend to the wound will often expedite wound healing. External fixation offers key advantages including: the promotion of stability across several joints; the ability to apply them distant from potentially infected bone; and the ability to apply them in the presence of open soft tissue envelope. Proponents of circular frames indicate that patients can begin early weightbearing. This is especially true with the Ilizarov style frames, which allow surgeons to dissipate weightbearing forces through a set of wires and frames proximally in the lower extremity. This will often counteract the disuse osteopenia that results in these patients from long-term nonweightbearing or immobilization. In regard to static circular frames (i.e. Ilizarov–style), they provide stability and correction of deformity but little in the way of compression. It is not unusual to add internal fixation along with external fixation to provide the necessary compression. One can make these types of frames dynamic by removing one or two struts later during the course of treatment. This will allow some motion at the fusion site when patients ambulate, thus stimulating bone growth. One can use dynamic frames such as the Taylor Spatial Frame in the acute phase of Charcot to slowly distract and reduce joint subluxation. After achieving an optimum position of correction, the device can compress the joints and lock the struts until treatment is deemed complete. More commonly, however, surgeons will insert rigid internal fixation and remove the frame once the deformity is reduced.1 The major disadvantages to circular frames have been the risk of pin tract infections, the weight of the frame and patient acceptance of the frame. Pin tract problems, especially infections, result from micromotion at the pin-skin interface and the fact that these frames remain in place for as long as three months. Infection rates have decreased significantly since the introduction of skinny wires over half pins. However, pins can still loosen and one may need to replace these during the course of treatment. Surgeons should also forewarn the patient that a second surgery will be necessary, whether it is for removing the frame and inserting internal fixation or for removing the frame alone.
Finally, no matter how much you discuss, describe and prepare the patient for the fact that he or she will be living with this frame for three months, almost all patients are in a state of shock when they wake from anesthesia and discover this “contraption” attached to their leg. When it comes down to removing the frame, it is dictated by the patient tiring of the device as much as the clinical result. In our practice, we have resorted to showing the surgical patient a completed frame attached to a sawbone so he or she can appreciate the impact of the device. Dr. Giurini is the Chief of the Division of Podiatric Surgery at the Beth Israel Deaconess Medical Center in Boston. Dr. Steinberg (shown at right) is an Assistant Professor in the Department of Surgery at the Georgetown University School of Medicine in Washington, D.C. He is a Fellow of the American College of Foot and Ankle Surgeons. For related articles, see “Active Charcot: Should You Proceed With Surgery?” in the March 2005 issue of Podiatry Today or “Key Considerations In Managing The Charcot Foot” in the May 2005 issue. Also be sure to check out the archives at www.podiatrytoday.com.
1. Personal communication with Bradley Lamm, DPM.