Current Concepts With External Fixation And The Charcot Foot

Combining a thorough review of the literature with insights from their surgical experience, these authors assess the role of external fixation and offer recommendations in procedure selection for addressing deformities in patients with Charcot neuroarthropathy.

The original application of external fixation in Charcot neuroarthropathy included static fixation following corrective osteotomies and/or arthrodesis. In 1996, Sticha and colleagues reported on the use of Kirschner wire fixation and three unilateral mini-external fixators for midfoot arthrodesis in patients with chronic Charcot neuroarthropathy deformity.1 Wang and coworkers utilized hybrid external fixation in 2002 for successful arthrodesis of 28 non-ulcerated patients with Charcot neuroarthropathy in combination with tendo-Achilles lengthening and bone stimulation.2 Farber and colleagues demonstrated good results with ulcer excision and open osteotomy with static external fixation.3 In 2002, Cooper found more varied results in a group of 100 patients using acute open reduction with mostly static external fixation.4

   In 2006, Pinzur used circular external fixation to maintain alignment of deformity correction in high-risk, obese patients with Charcot neuroarthropathy.5 The ability to use external fixation safely in cases of large bone loss due to infection established an advantage in treating severe Charcot neuroarthropathy foot and/or ankle osteomyelitis. Pinzur reported a single-staged technique in 26 high-risk patients with midfoot Charcot neuroarthropathy and osteomyelitis via resection of the infected bone, deformity correction with circular external fixation, and culture-specific parenteral antibiotic therapy.6 In 2007, Lamm and Paley advocated gradual deformity correction using Ilizarov external fixation for severe Charcot neuroarthropathy dislocations and deformities.7 They cited the benefits of a minimally invasive technique without sacrificing foot length, limiting neurovascular compromise and allowing partial weightbearing.

   Since then, other authors have reported on their results using single- or multiple-staged limb salvage for diabetic Charcot neuroarthropathy osteomyelitis of the foot and/or ankle.8,9 The versatility of external fixation with appropriate technique has also allowed surgeons to combine this with internal fixation such as intramedullary nails or locking plate technology for Charcot neuroarthropathy.10,11 Although there is controversy in this area, surgeons have applied external fixation in the acute stage of Charcot neuroarthropathy and/or in acute neuropathic fractures to prevent joint collapse and subsequent deformity.12 In recent years, with the increased use of soft tissue reconstruction in patients with Charcot neuroarthropathy, creatively designed external fixators have also become an additional tool to properly offload grafts or flaps in patients who are unable to tolerate conventional techniques such as cast immobilization.13

Identifying The Challenges With Diagnosis

The clinical presentation of Charcot neuroarthropathy is varied and its pathophysiology is still unknown. Some of the most common theories have suggested that autonomic and/or sensory neuropathy may predispose the patient with diabetes to the initial cascade of the Charcot neuroarthropathy process. Other suggestions have concentrated on pro-inflammatory cytokines, glycosylated tendon(s), biomechanical lower extremity alterations, digital or partial foot amputations, severe infection/cellulitis, osteomyelitis, decreased bone mineral density and vitamin D levels.14-17

   However, even though the prevalence of Charcot neuroarthropathy is increasing in the diabetic population, most patients are unaware of the condition and do not seek medical attention until the later stages of Charcot neuroarthropathy. In the early stages of Charcot neuroarthropathy, patients are often diagnosed with cellulitis, infection, sprained ankle or foot ligaments or gout. Alternately, clinicians may test these patients for an incidence of superficial or deep vein thrombosis since plain foot and/or ankle radiographs initially may not show any osseous Charcot neuroarthropathy abnormalities. At that point, cumulative microtrauma from an unprotected weightbearing status may further lead to multiple foot and/or ankle fractures, joint dislocations with subsequent deformities, ulcerations and infections.

Pertinent Principles With Procedure Selection

The preoperative medical optimization, testing and counseling can be quite extensive in the patient with diabetic Charcot neuroarthropathy since the patient’s health is usually affected by multiple medical comorbidities including and not limited to the cardiac, renal and vascular systems. Once both the medical and surgical teams have clearly identified and addressed the preoperative concerns, the patient may proceed with the necessary surgical reconstruction. One can categorize the surgical procedure based on the location of the deformity, the presence of unstable joints, presence of ulceration and/or osteomyelitis.

   In patients with isolated diabetic Charcot midfoot deformities, surgeons may perform single or multiple joint arthrodesis procedures in either the medial or lateral columns of the foot. For example, one may combine a tarsometatarsal joint arthrodesis with a naviculocuneiform arthrodesis or with the entire medial column (talo-navicular-cuneiform-metatarsal) arthrodesis when necessary. In the absence of any wounds and/or osteomyelitis, rigid internal fixation (screws, plating, beaming) may play a key role in achieving the necessary stability and union at the arthrodesis site(s).

   Surgeons may also consider internal fixation when the patient presents with non-infected wound(s), no history of osteomyelitis and no growth of organisms after the initial surgical debridement of the wound(s) associated with the diabetic Charcot neuroarthropathy deformity. Medial column diabetic Charcot neuroarthropathy foot deformities are usually more stable in comparison to those at the lateral column in the chronic stages of Charcot neuroarthropathy, and one may address recurrent ulcerations with an exostectomy and plastic surgical closure of the non-infected wound when necessary. In the presence of medial and/or lateral column instability, an isolated, adjacent and/or entire column arthrodesis can result in long-term successful results.

   In contrast, when a patient with diabetic Charcot neuroarthropathy midfoot deformity presents with a history of osteomyelitis and/or infected ulcerations, a staged reconstruction may be necessary to eradicate the associated soft tissue and osseous infection before the definitive procedure.18 The initial surgical intervention includes a thorough surgical debridement and obtaining the necessary soft tissue and osseous specimens for microbiology and histopathology analysis. Following those results, a timely infectious disease consultation will provide further guidance for short- and long-term oral and/or parenteral antibiosis for the compromised patient with diabetic Charcot neuroarthropathy. The use of cemented non-biodegradable antibiotic beads and/or spacers may also be necessary for further local resolution of soft tissue and/or osseous infection, stability and the elimination of any large defects.6 In these surgical reconstruction procedures, external fixation provides an ideal surgical tool to address the diabetic Charcot neuroarthropathy deformity.

When Patients Have Isolated Rearfoot And Ankle Deformities

In patients with isolated diabetic Charcot neuroarthropathy rearfoot/ankle deformities, surgeons may perform a single or multiple joint arthrodesis procedures depending on the location, associated soft tissue or osseous infection and severity of deformity. These clinical case scenarios are more complex and early intervention based on their inherent instability might be necessary to prevent further skeletal architecture collapse with subsequent ulceration, infection and/or lower extremity amputation.

   Surgical procedures for this category of patients may include and are not limited to isolated ankle, subtalar, triple, tibiotalocalcaneal or pantalar arthrodesis in order to provide solid union across single or multiple joints. In clinical case scenarios with a severe diabetic Charcot neuroarthropathy talus dislocation, a single or staged talectomy with tibiocalcaneal or tibiocalcaneonavicular arthrodesis may be necessary to correct the deformity. As we discussed previously with the diabetic Charcot neuroarthropathy midfoot deformities, rigid internal fixation in the form of screws, locking plating and/or intramedullary fixation plays a crucial role in providing osseous union across the arthrodesis site(s). Careful consideration is necessary for the use of internal fixation in the presence of non-infected wound(s) while external fixation may become ideal in cases of previously resected osteomyelitic joints and eradicated soft tissue infections.

   The use of cemented non-biodegradable antibiotic spacers or antibiotic-coated nails is also beneficial for largely resected osseous defects of the diabetic Charcot neuroarthropathy rearfoot/ankle and before the definitive surgical procedure.19,20 Adjunctive therapies and/or procedures for the diabetic Charcot arthropathy midfoot and/or rearfoot/ankle may include the utilization of autogenous or allogenic bone grafting; bone growth stimulation; equinus correction; and/or skeletal stabilization of joints distal and proximal to the arthrodesis site(s).

Essential Considerations With External Fixation

General indications of external fixation use for the foot and ankle include and are not limited to unstable and/or non-braceable Charcot neuroarthropathy deformities; malunions; nonunions; deformities with associated soft tissue and osseous defects; a previous history of osteomyelitis or septic joint; and salvage of failed internal fixation. These clinical scenarios are often associated with poor bone stock, retained and/or broken hardware, severe deformity, residual infection and wound healing complications. In certain cases, surgeons can supplement the use of internal fixation with external fixation to enhance osseous stability and healing. The requirements for combined internal fixation with external fixation are adequate soft tissue coverage, bone quality amenable to fixation and an absence of infection.

   In the diabetic population, external fixation may be indicated in the acute management of certain ankle fractures and/or dislocations to provide further stabilization in the presence of dense peripheral neuropathy. In addition, external fixation can also supplement the use of internal fixation in order to avoid the possible development of acute Charcot neuroarthropathy with unstable fracture patterns and early, unwanted weightbearing status. Other indications include the management of limb-threatening wounds associated with Charcot neuroarthropathy that require adjunctive wound care, plastic surgery, and/or offloading to promote healing of the associated soft tissue envelope.21 In addition, surgeons can use external fixators to shorten osseous segments to obtain wound closure as they provide simultaneous compression, stabilization and the ability to make necessary adjustments if necessary during the postoperative period.

   One should exercise caution in considering external fixation when dealing with severely immunocompromised patients who have severe peripheral vascular disease and critical limb ischemia not amenable to revascularization, certain cases of untreated active infection with systemic manifestations and/or non-ambulatory patients with severe multiple medical comorbidities. As such, amputation may be preferable in similar clinical case scenarios in order to avoid devastating postoperative surgical outcomes. Obtaining a thorough social history is important to identify and address concerns pertaining to excessive smoking and/or alcohol consumption, family support and psychosocial issues, adherence with treatment and medications, working status and/or activity level since these factors all have equal importance in facilitating optimal outcomes.

   If postoperative complications with external fixation occur, it is necessary to address these in an expedited manner to avoid any unwanted results including wire or half-pin breakage, osseous and soft tissue infections, external fixation instability, malunion, nonunion, fractures and/or joint dislocations. As we mentioned previously, patients with Charcot neuroarthropathy may present with decreased bone mineral density and cortical stiffness. Accordingly, close postoperative monitoring, gait training and guidance is necessary to avoid any major complications. Extensive training with the diabetic Charcot neuroarthropathy deformity and utilization of external fixation are necessary to minimize the incidence of postoperative complications.

In Summary

The history, clinical presentation and treatment of each Charcot neuroarthropathy deformity of the foot and ankle may be different and dependent on the severity of multiple systemic and/or clinical manifestations. Despite the availability of improved technological advancements such as external fixation in treating these deformities, additional studies with higher levels of evidence and cost analysis are necessary to determine its exact efficacy in this varied patient population.

   Dr. Ramanujam is an Assistant Professor/Clinical in the Department of Orthopaedic Surgery within the Division of Podiatric Medicine and Surgery at the University of Texas Health Science Center San Antonio in San Antonio.

   Dr. Stapleton is the Chief of Podiatric Surgery at Lehigh Valley Hospital in Allentown, PA, and a Clinical Assistant Professor of Surgery at the Penn State College of Medicine in Hershey, PA. He is a Fellow of the American College of Foot and Ankle Surgeons, and is an Associate in Foot and Ankle Surgery with VSAS Orthopaedics in Allentown, PA.

   Dr. Zgonis is an Associate Professor and the Externship and Fellowship Director in Reconstructive Foot and Ankle Surgery in the Department of Orthopaedic Surgery within the Division of Podiatric Medicine and Surgery at the University of Texas Health Science Center San Antonio in San Antonio. He is a Fellow of the American College of Foot and Ankle Surgeons.

References

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