Current Insights On Classifying Charcot Arthropathy
Before the advent of insulin, death from diabetes occurred early in the disease process. Now people with diabetes are living longer and long-term complications of the disease are more common. One such complication is Charcot arthropathy and since the early report by Jordan linking it to diabetes, the number of case reports has steadily increased.1
Although the etiology of Charcot arthropathy is largely unknown, it is well recognized that this condition can occur in conjunction with any peripheral neuropathy. Researchers have found that Charcot arthropathy is associated with tabes dorsalis, syringomyelia, congenital insensitivity to pain, alcohol abuse, sarcoma of the spine, leprosy and recently, HIV-associated neuropathy.2-10 Today, diabetes is the most common cause of Charcot arthropathy.
Charcot arthropathy is a rapidly progressive and debilitating process, and the natural progression is well documented. J.M. Charcot, through detailed clinical observation, described the bone and joint changes associated with this condition. Acute Charcot arthropathy of the foot is characterized by inflammation. Clinical signs and symptoms of inflammation include profound unilateral edema, localized skin temperature increase and erythema. The affected foot may be as much as 9 to 11º F warmer than the same point on the contralateral limb.
These initial clinical signs and symptoms of inflammation precede bone and joint involvement. In acute Charcot, radiographs may appear normal. After the initial inflammatory phase, further trauma leads to progressive bone and joint destruction that becomes easily visible on radiographs (see “What You Should Know About Imaging And Charcot” on page 26).
A Guide To The Eichenholtz Classification
Attempts to define the natural course of Charcot arthropathy have produced a number of classification systems. In 1966, Eichenholtz classified the sequence of changes in “Charcot joints,” which he observed via serial radiographs.13 He divided these changes into three stages.
The predictable sequence of changes began with Stage 1 (stage of development), which is distinguished by clinical signs and symptoms of inflammation (warmth, erythema and edema) and the visibility of radiographic changes. Common radiographic findings include bone debris formation at the articular margins, fragmentation of the subchondral bone, subluxation, dislocation and capsular distention.
Eichenholtz stage 2 (stage of coalescence) is marked by decreased warmth, erythema and edema. Radiographs show absorption of fine debris and fusion of large fragments to adjacent bones. The bone ends become sclerotic. At this point, the deformity ceases to progress and transitions to the reconstructive or remodeling stage.
Stage 3 (stage of reconstruction or remodeling) is characterized by rounding of the bone ends with a decrease in sclerosis, leading to consolidation. A structural bone deformity may be present and this resultant deformity may lead to skin breakdown and potential infection followed by amputation.
This staging system is known as the Eichenholtz classification and has become widely accepted. This classification system is based primarily on radiographic changes. Therefore, it neglects the initial inflammatory phase in which there are no bone changes visible on plain radiographs.
Later, Shibata, et al., added a stage (Stage 0) to the Eichenholtz classification. This stage describes warmth, dull pain, swelling and joint instability, with normal appearing bone and joints on radiographs.14 Yu and Hudson described Stage 0 Charcot as an acute sprain or fracture in the presence of neuropathy, and the authors reviewed the evaluation and treatment of this stage in the Charcot foot and ankle.15
Sella and Barrette developed an anatomic classification scheme which includes a “pre-radiographic” clinical Stage 0, consisting of localized heat and swelling.16 Armstrong and Lavery introduced a practical, two-part staging system, indicating that the foot is either “acute” or “post-acute (quiescent).”17
Pertinent Points On The Sanders/Frykberg System
Several authors have developed anatomically based classification systems by observing the patterns of involvement in the foot and ankle.16,18-20Sanders and Frykberg classified Charcot arthropathy anatomically into patterns of joint involvement.18 The authors divided the foot and ankle into five patterns of destruction.
Pattern I involves the forefoot joints and common radiographic changes include osteopenia, osteolysis, juxta-articular cortical bone defects, subluxation and destruction.
Pattern II involves the tarsometatarsal joints including the metatarsal bases, cuneiforms and cuboid. Involvement at this location may present as subluxation or fracture/ dislocation, and it frequently results in the classic rocker bottom foot deformity.
Pattern III involves Chopart’s joint or the naviculocuneiform joints. Radiographic changes typically show osteolysis of naviculocuneiform joints with fragmentation and osseous debris dorsally and plantarly.
Pattern IV involves the ankle with or without subtalar joint involvement. Radiographs reveal erosion of bone and cartilage with extensive destructive of the joint, which may result in complete collapse of the joint and dislocation. Typically, this pattern of involvement results in a severe unstable deformity.
Pattern V is isolated to the calcaneus and usually results from an avulsion of the Achilles tendon off the posterior tubercle. The authors reported the midfoot (patterns II and III) to be the most common area of involvement and these patterns are often associated with plantar ulceration at the apex of the deformity.18
A Primer On The Brodsky And Rouse Classification
Similarly, Brodsky and Rouse described four distinct anatomical areas of the foot and ankle that are most commonly affected by Charcot arthropathy.19
Type 1 accounts for up to 70 percent of cases and involves the metatarsocuneiform and naviculocuneiform joints (midfoot). This midfoot involvement often leads to a rocker bottom foot with symptomatic bony prominences and often results in skin breakdown plantarly at the apex of the deformity.
Type 2 involves the subtalar, talonavicular or calcaneocubiod joints (hindfoot), and accounts for up to 20 percent of the cases. Type 3 is divided into “A” (ankle) and “B” (posterior calcaneus). This type affects approximately 10 percent of patients and occurs mainly in the ankle. Type 2 and type 3 involvements are most likely to result in instability.
This classification system fails to include multiple regions of involvement. Most notably, it does not include the forefoot and has been modified to include Type 4 (multiple regions) and Type 5 (forefoot).21
How Schon Classifies Midfoot Deformities
Schon, et al., developed a classification system, which further categorized midfoot deformities. They concluded that midfoot deformities can be classified as one of four types based on the anatomic location with the most significant involvement.20 The patterns include: Lisfranc, naviculocuneiform, perinavicular and transverse tarsal patterns of deformity.
The Lisfranc pattern will have significant involvement at the metatarsocuneiform joints. One may see the naviculocuneiform pattern when the deformity occurs more proximally at the naviculocuneiform joint. The perinavicular pattern includes the navicular and its adjacent bones, and the transverse tarsal pattern involves significant deformity at the talonavicular joint.
Schon also included three stages of severity (A-C) based on the degree of collapse in the sagittal plane as shown on lateral weightbearing radiographs.
Stage A is the least severe as the deformity does not collapse to the level of the plantar surface of the foot. Stage B deformities collapse to the level of the plantar surface of the foot.
Stage C represents the most severe deformity in which the midfoot is collapsed beneath the level of the plantar foot. This deformity represents a rocker bottom foot and is often associated with plantar ulcerations.
A Closer Look At A Five-Stage Classification
Sella and Barrette developed a five-stage classification scheme for medial column neuropathic joint disease based on radiographs, clinical findings and bone scans.16 This system divides the medial column of the Charcot foot into five clinical stages.
This system includes an early phase, Stage 0, which consists of localized heat and swelling of the medial column. Radiographs are normal. Stage 1 follows and early bone involvement is visible on radiographs. Radiographic findings include localized osteopenia, subchondral cysts, erosions and possibly diastasis. Stage 2 consists of joint subluxation and once dislocations and joint collapse occur, the patient reaches Stage 3. Stage 4 represents healing and radiographic findings include sclerosis and fusion of affected bone and joints.
The anatomic-based classification systems provide insight into the frequency and patterns of bone and joint involvement, but none of these classification schemes is able to predict outcomes. Patient outcomes depend not only on the anatomic site of involvement but also the presence of an ulceration and osteomyelitis.
Could A New Charcot Classification Help Predict Amputation Risk?
Recently, Rogers and Bevilacqua proposed a new classification scheme, which accounts for the degree of complications in the Charcot joint (see “A Guide To A New Charcot Classification System” on page 24).22 This new system considers deformity, ulceration and osteomyelitis, and may be helpful in predicting amputation.
This is a two-axis system (XY) and combines the features of the clinical exam, radiography and anatomy. The X-axis marks the anatomic location of involvement and the foot and ankle are divided into three regions: forefoot, midfoot and rearfoot/ankle. The Y-axis describes the degree of complication in the Charcot joint. A is acute Charcot with no deformity, B is Charcot foot with deformity, C is Charcot foot with deformity and ulceration, and D includes osteomyelitis. Therefore, one moves across the X-axis (anatomic involvement) and/or down the Y-axis (complicating factors) as the Charcot foot becomes “more complicated” and is accordingly at greater risk for amputation.
We postulate that a 1A Charcot foot (acute Charcot arthropathy localized to the forefoot) is relatively simple and at lower risk for amputation in comparison to a 3D Charcot foot (rearfoot and/or ankle involvement with underlying osteomyelitis). The proposed classification system has not been correlated with patient data. However, studies are currently underway to evaluate the effectiveness of this classification scheme in predicting amputation.
The goal of any classification system should be to improve communication between physicians and help them identify and communicate risk to patients and their families. An ideal classification system provides important clinical information to assist in establishing appropriate treatment options and setting reasonable goals in treatment. Such a system may also serve as a prognostic tool to predict outcomes.
If one diagnoses Charcot arthropathy early in the acute phase and treats it appropriately, one can avert major deformity. However, a delay in diagnosis and treatment results in worsening outcomes. Continued trauma to an insensate foot leads to extensive bone damage, resulting in a severe, unstable deformity.
The aforementioned classification schemes are helpful in understanding the evolution and anatomic patterns of destruction. However, early recognition is most important in the overall treatment of these patients. One should closely monitor and immobilize any patient with neuropathy who presents with even a minor foot and ankle injury. Successful outcomes largely depend on the early recognition.
Appropriate treatment is based on the acuteness of the symptoms, the pattern of destruction, the presence of ulcerations and soft tissue or bone infection.23 If conservative therapy fails or if patients present with an unstable foot or ankle, surgical intervention is indicated. Surgical correction and stabilization can be effective in preventing further deformity and ulcer recurrence.
Dr. Bevilacqua is an attending surgeon within the Section of Foot and Ankle Surgery/Amputation Prevention Center at Broadlawns Medical Center in Des Moines, Iowa.
Dr. Steinberg is an Assistant Professor in the Department of Plastic 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.
Editor’s note: For related articles, see “A Closer Look At Redefining Charcot” in the August 2006 issue, “Point-Counterpoint: Active Charcot: Should You Proceed With Surgery?” in the March 2005 issue, or “Current Concepts In Treating Acute Charcot’s Arthropathy” in the September 2006 issue.
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