What is Charcot Foot?
Chief Complaint: Red, swollen leg
A 64 year-old male with a past medical history of poorly controlled diabetes, HTN, HLD presents to the ED complaining of 1 month history of a warm, swollen right lower extremity. He first noticed it 1 month ago while landscaping. His boss became concerned about the appearance of the leg and took him to City MD, where he was diagnosed with cellulitis and given a course of doxycycline and Bactrim, which he completed without relief of his symptoms. The patient denies pain to the leg and states he only feels a nagging stabbing pain in the dorsal midfoot. He denies fevers, chills, or systemic symptoms. No history of DVT or PE. He takes lisinopril. He has a prescription for metformin but has only taken one pill stating that he does not know how to take it.
T: 36.8 F, BP: 145/70, HR: 89, SaO2: 99% RA, Gluc 288
Diffusely swollen, erythematous leg which is warm
Foot swelling with prominent midfoot, rocker bottom appearance
Skin is warm to touch and non-tender to palpation. No noted ulcers, wounds
Foot feels full. No significant tenderness but patient points to dorsal midfoot as area of pain
Cellulitis, DVT, Osteomyelitis
134/100/18 Gluc: 288
WBC: 8.4, Hg: 11.8, Hct: 34.2, Plt: 222
Lactic acid 1.7, ESR: 41, CRP: 1.7
RLE duplex – Negative
Take Away #1
Charcot foot – a.k.a Charcot neuropathic osteoarthropathy – is a rare and disabling disorder. It is an acute inflammatory condition most commonly caused by diabetes today (syphilis in the past). Diabetic peripheral neuropathy makes the foot insensate, leading to an inadequate protective mechanism of the foot and recurrent microtrauma and bone injury. Neurovascular dysregulation disease leads to increased blood flow and bone resorption. In addition, activation of inflammatory cytokines leads to further destruction. Over time, this leads to progressive destruction of joints with fractures, subluxations, and erosion of bones, especially at the midfoot. If left untreated, it can lead to significant disability and amputation.
Take Away #2
Being able to differentiate Charcot foot from other diabetic foot complications is crucial. It’s easy to misdiagnose Charcot foot as other conditions common in diabetic patients, such as cellulitis, osteomyelitis, DVT, gout, or sprains. One in four cases of acute Charcot foot are misdiagnosed, leading to a delay of diagnosis of seven months on average. This is a crucial time during which irreparable joint damage continues to occur. By the time the classic “rocker-bottom” foot abnormalities occur from midfoot arch collapse, the risk of lower extremity amputation increases 15-to-40-fold. As emergency physicians, we should keep this condition our differentials when managing diabetic foot complications, especially if the patient’s history or lab values aren’t consistent or do not support other diagnoses.
Classical presentation is a unilateral, swollen, warm lower extremity with minimal or no associated pain. Patients are typically afebrile with normal vital signs. Although they can be associated with ulcers, the absence of a skin lesion should increase your suspicion for the diagnosis. If the leg is raised for 5-10 minutes, the erythema from Charcot foot should dissipate, differentiating it from cellulitis. Additionally, lab markers for infection such as CBC, ESR, CRP are typically normal or only mildly elevated.
Although this case was diagnosed on X-ray, this can be difficult in cases with less advanced disease, and thus more sensitive imaging can be used including CT, which will demonstrate midfoot subluxations and minimally displaced fractures. The gold standard imaging modality is MRI, which will demonstrate bone marrow edema and secondary changes in periosteal soft tissues.
Take Away #3
Management of Charcot foot – The most important component of management is simply to stop weight bearing on the affected foot by having the patient placed in a total contact cast, which distributes pressure away from the foot, usually with consultation of a podiatrist. The patient can then go with crutches if tolerated. Follow up with podiatry is imperative, as these patients will need immobilization with orthotics and/or multiple cast changes for at least three months, or until resolution of edema and warmth. Endocrine follow-up for glycemic control should also be established.
Jose Torres, MD is a current second year resident at Stony Brook Emergency Medicine.
Edited by Bassam Zahid, MD