Limb Salvage And The Charcot Foot: What The Evidence Shows
Treating Charcot foot deformities can be quite challenging. Accordingly, these authors discuss the etiology and diagnostic keys with this condition, weigh in on various surgical options, and share emerging perspectives on fixation and the potential of orthobiologics in facilitating limb salvage.
Patients with diabetes can have an extensive medical and hospitalization history. This is especially the case for patients who have poor glycemic control, peripheral neuropathy and/or Charcot neuroarthopathy. It is estimated that an ulceration precedes about 84 percent of lower extremity amputations performed on patients with diabetes.1
It may seem that once a patient has a deformed foot that requires intense supervision, a major amputation (below the knee or above the knee) may be more cost effective than reconstruction. Recent analysis demonstrates that lifelong costs for major lower extremity amputations can be about $509,275, which is about three times higher than the costs for patients undergoing reconstruction.2-4 The cost for a patient after amputation depends on three characteristics: the type of prosthetic device, the level of limb loss and the functional capability of the individual.2
The mean costs for patients with amputations will continue to rise due to increasing life expectancy, the number of multiple prostheses an individual will utilize and the use of more technologically advanced prostheses.5 Greater health benefits with lower healthcare costs start with intensive glycemic control and optimal foot care.5
The cost of care for a patient with diabetes with a lower extremity ulcer in comparison to one without an ulcer presents a major economic difference.6 The best and most cost-effective way of treating patients with diabetes with lower extremity ulcers and/or Charcot changes to their feet is by utilizing a team approach. This team should be composed of a podiatric surgeon as a “quarterback” along with a primary physician, vascular surgeon, endocrinologist and an infectious disease specialist.6 Numerous studies have demonstrated that a team approach to diabetic foot conditions is effective in amputation prevention as well as reducing healthcare costs.5,6
What You Should Know About The Etiology Of Charcot And Subsequent Complications
Physicians who may treat or specialize in patients with diabetes will encounter Charcot neuroarthropathy. French physician Jean-Martin Charcot first described the condition as an arthropathy associated with tabes dorsalis or progressive locomotor ataxia.7 Today, Charcot most commonly occurs in patients with diabetic neuropathy. Charcot is a progressive disabling disorder that requires early diagnosis and attention to prevent further complicating factors. Such factors include a “rocker bottom” talus, which can lead to chronic plantar wounds, subsequent infectious processes with frequent hospitalization and increasing risks for lower limb amputation.8
Diagnosis begins with a heightened clinical suspicion of a patient with a red, hot, swollen foot.8,9 One can stage Charcot radiographically with the Eichenholtz system.10 Recently, Shibata and colleagues added a stage 0 for a foot demonstrating warmth, swelling, dull pain and joint instability in the midfoot even with normal radiographic features.11
Charcot is a vicious cycle that waxes and wanes through stages of fragmentation, coalescence and reconstruction. These stages occur at the weightbearing surfaces.12 A very common biomechanical deformity in patients with Charcot is equinus.12 Patients with diabetes deposit glucose in soft tissues, resulting in decreasing elasticity.
Glycosylation in the Achilles tendon can cause equinus deformity, which will increase plantar pressures on the forefoot and ultimately increase forces on the midfoot.12 The glycosylation of soft tissues along with increased forces can cause a cascade of events leading to rupture of the plantar fascia and further ligament and tendon failure. One may also see eventual further collapse and instability of the Charcot hindfoot.
We believe that subsequent architectural changes can be expected due to this progressive unstable process. Ultimately, goals for an acute Charcot patient are to avoid dislocation, fractures, instability and ultimately a deformity, which can compromise the stability of the patient’s foot. Another goal is preventing ulceration formation.12
A Few Thoughts On Initial Treatment Of Acute Presentations
When there is an initial acute presentation, one needs to pursue immobilization via total contact cast, Charcot restraint orthotic walker (CROW) boots or fiberglass casts.13,14 The patient must understand that these are non-weightbearing devices and the use of wheelchairs, crutches and Roll-A-Bout walkers are mandatory during the early Charcot stages.
It is not recommended to place non-adherent patients in a fracture walker due to ease of removing the device. Anecdotally, patients who have not had immobilization during their acute presentation are at a higher risk of forming a more severe fixed deformity with a plantar osseous prominence.
A study from 2002 demonstrated that if patients with Charcot arthropathy started on a bisphosphonate, their symptoms and disease activity would be more significantly reduced than if they were only immobilized.13 We have not experienced these clinical findings.
Current Perspectives On The Timing Of Surgery And Different Surgical Options
Forty percent of patients with Charcot midfoot disease who had been managed primarily with conservative care may require surgery.14 Patients who have recurrent chronic ulcerations with radiographic evidence of plantar prominences due to Charcot may be candidates for exostectomy of the osseous deformity. Surgeons can perform exostectomy with either a longitudinal medial or longitudinal lateral incision (whichever side is closer to the prominence) along with full thickness dissection to the osseous structure.15 We have had a significantly higher success rate with medial versus lateral exostectomies in selected patients who have a “stable mature deformity.”
It is very important to obtain deep cultures, especially with patients who have had a chronic ulceration. One of the factors that may be preventing the ulcer from healing is a subclinical infection or chronic osteomyelitis.15
One should reserve exostectomy of the bony plantar prominence for the more stable Charcot foot. Patients who have an increased amount of instability as well as multiplanar deformities will respond more suitably to reconstruction.
Surgical reconstruction of the Charcot lower extremity does not have an acceptable treatment algorithm. Surgeons should tailor treatment to each individual patient and the deformity.16 We strongly feel that “cookbook surgery” will not yield predictable results. Surgical reconstruction of these deformities involves specialized training and should be performed by those surgeons at institutions with a supportive care team. Surgical intervention is recommended when appropriate conservative treatments have failed.
The controversial question is: At what stage of Charcot should patients undergo reconstructive surgery? Simon and colleagues performed arthrodesis on early stage Charcot patients with no immediate or long-term complications.17 All patients regained the level of walking ability they experienced previously. However, fixation of bone in the area of dissolution can be difficult and sometimes not possible due to the poor quality of the bone, which may lead to a high rate of fusion failure.18 It may be in the surgeon’s best interest to wait until the patient has a later stage of Charcot and coalescence is present.
As we noted earlier, there is no set treatment or approach for reconstruction. Most patients will possess an equinus deformity that one will need to address in order to decrease forces at the forefoot and midfoot. Either a percutaneous tendo-Achilles lengthening, open Achilles lengthening or gastrocnemius recession, depending on the level of the equinus, is indicated in these instances.
Charcot is a multiplane deformity. If the midfoot is affected, an arthrodesis is very effective in addressing all planes of deformity. If the Charcot is affecting the hindfoot, a talectomy with a pantalar arthrodesis will help position the foot appropriately and once again address all planes of the deformity.
Key Considerations With Fixation
Appropriate fixation can be very challenging and difficult. Fixation can occur singly or in combination with internal screws, internal plate(s), external circular fixation, intramedullary nail and Steinmann pins.
It has become increasingly acceptable to perform the reconstruction with a combination of internal and external fixation. This allows stress shielding of the arthrodesis site, assists in prevention of bending and torsional forces, and acts as a deterrent to inappropriate weightbearing.16 External fixation alone is a useful technique although a potential complication such as pin tract infection could lead to premature removal of the device, leaving the patient without any fixation.
Internal fixation techniques for Charcot reconstruction have evolved into a contemporary technique known as the superconstruct. The superconstruct can be defined by four factors:
• fusion extending beyond the zone of injury to include joints that are not affected in order to improve fixation;
• bone resection performed to shorten the limb to allow for adequate reduction of deformity without undue tension on the soft tissue envelope;
• use of the strongest device that the soft tissue envelope can tolerate; and
• application of devices in a position that maximizes mechanical stability.18
By “beaming” the medial and lateral columns, one is providing a permanent compensation for the altered morphology, elasticity and tensile strength of the ligamentous and tendon structures, which have failed and progressively collapsed.19 Note that no matter which fixation technique one chooses, there is the chance of failure. Patients and their families need to be aware of this. A Charcot reconstruction is a major surgery, which is an attempt to salvage the lower extremity in an effort to prevent a more major amputation.
A Closer Look At The Potential Of Orthobiologics
Orthobiologics can assist in the fusion of the arthrodesis site, especially in patients with diabetes, who have a significantly lower expression of platelet-derived growth factor beta (PDGF-β), transforming growth factor beta (TGFβ1), and insulin-like growth factor (IGF-I) mRNA in fracture callus formation.20 It is important to use both osteoinductive as well as osteoconductive products to assist in the activation and stimulation of bone growth.
Platelet-rich plasma (PRP) is a concentration of platelets above the normal physiologic levels. When one activates PRP, it will set the stage for healing and regeneration with increased growth factors, including PDGF, TGF, IGF, vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF).
Research has shown all these factors assist in various stages of osseous and soft tissue healing.21 When one combines PRP with an allogenic cancellous bone graft, the patient receives both osteoinductive and osteoconductive properties. Bone morphogenetic proteins (BMPs) are modulators of osteoprogenitor and mesenchymal cells during osseous healing. The BMPs induce new bone formation by way of endochondral ossification but only have osteoinductive properties.21
Recently, we have found Trinity Multipotential Cellular Bone Matrix (Orthofix) useful. This is an allograft stem cell product harvested from cadaveric iliac bone marrow aspiration, which is combined with allograft cancellous bone from the same cadaver. This product carries osteoinductive, osteoconductive and osteogenic properties. Since Trinity is non-immunogenic, it can be transplanted between genetically mismatched individuals without risk of immune system rejection.
Charcot neuroarthropathy affecting the lower extremity is a difficult disease to manage for both the patient and physician. No two patients will be similar nor is there a “cookbook” algorithm for treatment. Early diagnosis and treatment is critical. A team approach is essential for the patient’s success. The evidence shows that aggressive limb salvage can be both financially advantageous as well as beneficial for the patient’s health and well-being.
Dr. Pupp is the Co-Director of the Wound Care Clinic and a member of the Residency Training Committee at Providence Hospital in Southfield, Mich. He is a Fellow of the American College of Foot and Ankle Surgeons, and is board certified in foot and ankle surgery by the American Board of Podiatric Surgery.
Dr. Koivunen is the Chief Podiatric Resident at Providence Hospital in Southfield, Mich.
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17. Saltzman CL, Hagy ML, Zimmerman B, Estin M, Cooper R. How effective is intensive nonoperative initial treatment of patients with diabetes and Charcot arthropathy of the feet? Clin Orthop Relat Res 2005; 435:185-190.
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20. Lin S. Impaired bone healing in patients with diabetes mellitus. The University of Medicine and Dentistry of New Jersey. 2004. Available at http://www.theuniversityhospital.com/trauma/pdf/impaired.pdf
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For further reading, see “Emerging Concepts In Fixation For Charcot Midfoot Reconstruction” in the February 2011 issue of Podiatry Today.