Foot and Ankle cases 35
A 55-year-old man with a long history of type 2 diabetes presents with a swollen, erythematous, hot, and mildly tender right foot. The majority of his erythema is localized in his midfoot. He reports that he has had increased pain in his foot for the past week. He has been doing his regular foot care without any skin breakdown. In addition, he has had no fevers, chills, or elevated blood sugars. On physical examination his vital signs are stable. He has swelling in his right foot, but no visible ulcer. His pulse is strongly palpable, but he has decreased sensation bilaterally in a stocking distribution to the level of the mid tibia. In addition to concern for infection you wish to evaluate the patient for Charcot foot.
Which of the following is a more consistent physical examination finding in a Charcot foot than in an infected diabetic foot?
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Erythema which does not resolve with elevation
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Warmth
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Swelling
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Intact skin on the foot
Discussion
The correct answer is (D). Charcot foot is often confused with infection as both often present as red, hot, swollen, and occasionally painful feet. Classically, elevation of the Charcot foot will result in resolution of erythema, whereas in an infection erythema will remain with elevation. Osteomyelitis in a diabetic foot most often results from an adjacent ulcer as opposed to hematogenous spread. The definitive diagnosis however would be made from a pathologic specimen that demonstrates no organisms and bone fragments within the synovium.
A lateral x-ray of the patient’s foot is obtained (Fig. 5–69).
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Figure 5–69 Lateral weight-bearing foot radiograph demonstrating fragmentation and collapse through the midfoot.
The patient asks if this location for neuropathic joint changes in the foot is common. You respond:
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No this is very uncommon and almost case reportable
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This is the most common location for Charcot arthropathy
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Yes, this is a common location in the lower extremity, however there are other places which are more common locations
Discussion
The correct answer is (B). Charcot neuropathy is classified based both upon the location of the pathology in the foot (Brodsky) and stage of the disease (Eichenholtz). In the Brodsky classification, type 1 disease is in the midfoot, type 2 is in the hindfoot, type 3a is tibiotalar joint involvement, and type 3b is calcaneal tuberosity involvement. The most commonly affected region is the midfoot (type 1), often resulting in the classic rocker bottom deformity of the foot. Types 2 and 3 are less common. Type 3a however tends to be very difficult to control and can result in varus or valgus collapse and subsequent ulcer formation and osteomyelitis.
The Eichenholtz classification describes the stages based upon the pathologic progression of the disease from fragmentation through coalition. The pathologic changes of a Charcot joint begin with the fragmentation stage. This typically presents with osteopenia and joint subluxation, fracture, or dislocation. This is followed by the coalescence phase during which the progression of radiographic deformity halts as demonstrated on serial radiographs. The final stage is reconstruction, during which there is resolution of the inflammation and union of the fragmented regions. The end result often includes residual deformity, which may or may not be problematic.
The patient wants to know if he needs surgery at this point in time. You explain that there is no clear indication for surgery at this point given that there is no ulcer formation, or skin at risk.
You recommend initially treating him with a total contact cast, and nonweight bearing for this stage of his disease. The reason for this is:
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To prevent progression of collapse
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To increase rate of union
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For pain control
Discussion
The correct answer is (A). The goal of casting in the inflammatory stage is to prevent the progression of deformity which would result in ulcers. At the early fragmentation stage, there is a great degree of instability across the midfoot which may result in collapse and deformity. This can lead to worsened arch collapse and progression of the rocker bottom. The progression through the stages of Charcot neuropathy has not been tied to immobilization and often takes months to resolve. Many of these patients are nonpainful due to neuropathy. This results in the need for frequent skin evaluation to prevent skin breakdown in the cast.
After 8 months of follow-up the patient is found to have no further progression of his deformity and no erythema or warmth present. He still is having difficulty in shoewear, even with accommodative orthotics. He now presents with an ulcer on the plantar aspect of his foot (Fig. 5–70). Radiographs demonstrate no progression of deformity.
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Figure 5–70 Clinical photograph of the plantar foot.
The best treatment option at this point is:
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Below knee amputation
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Plantar exostectomy
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Triple arthrodesis
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Ankle arthrodesis
Discussion
The correct answer is (B). Since the patient has passed through the coalescence phase and failed accommodative orthotics, it is reasonable to proceed with a surgical intervention to relieve the pressure on the skin from the bony prominence. In this instance, the foot has a classic rocker bottom deformity. A plantar
exostectomy can relieve the pressure on the skin at this location. A below knee amputation is necessary in the setting of uncontrolled infection resulting in risk of life to the patient. A triple arthrodesis will correct deformity present in the talocalcaneal, talonavicular, and calcaneocuboid joints, however in this case the deformity is distal to the transverse tarsal joint, so would be of no benefit. The same is true for ankle arthrodesis. Additional procedures for correcting residual deformity of a Charcot foot include open reduction with internal fixation either with plates and screws or with intramedullary fixation (Fig. 5–71).
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Figure 5–71 Postoperative lateral radiograph demonstrating intramedullary fixation of midfoot Charcot arthropathy.
Objectives: Did you learn...?
Describe physical examination maneuvers to differentiate between osteomyelitis and Charcot joint?
Identify classification and staging systems of Charcot arthropathy?
Discuss procedures available for the treatment of residual deformity from neuroarthropathy in the midfoot?