Charcot Foot

Bilateral in 9 to 35%
Age typically over 40 years old
Most common in Diabetes Mellitus with Peripheral Neuropathy
1. Type I Diabetes patients are younger but with longer standing diabetes at diagnosis of Charcot Foot

Progressive deterioration of weight bearing joint as a complication of Peripheral Neuropathy
Sites of Neuroarthropathy
1. Medial tarsometatarsal joint (most common site)
2. Midfoot involvement accounts for 70% of cases
Theories of pathogenesis in Diabetes Mellitus
1. Neurotraumatic injury
  1. Repetitive minor Trauma to foot
  2. Loss of proprioception and Pain Sensation
2. Neurovascular injury
  1. Repetitive minor Trauma to foot
  2. Autonomic vascular reflex
    1. Hyperemia
    2. Periarticular Osteopenia

Atrophic Neuroarthropathy
1. Localized to forefoot
2. Osteolysis of Metatarsal heads
Hypertrophic Neuroarthropathy
1. Affects midfoot, rearfoot and ankle)
2. Sanders and Frykberg System (anatomical classification 1 to 5)
3. Eichenholtz Classification (clinical and radiographic criteria)
  1. Stage 0: Clinical (acute inflammatory)
    1. Erythema, edema, and warm foot
    2. No fever or skin break, normal XRay, normal CBC
    3. Often associated with minor Trauma History
    4. Early diagnosis critical to prevent progression
  2. Stage 1 Fragmentation (Acute Charcot)
    1. Periarticular Fractures and joint dislocations
    2. Unstable and deformed foot
  3. Stage 2 Coalescence (Subacute Charcot)
    1. Bone debris resorbed
  4. Stage 3 Reparative (Chronic Charcot)
    1. Fragments fuse, resulting in re-stabilization
    2. Stable, but deformed foot

Peripheral Neuropathy (esp Diabetes Mellitus) and Obesity in age over 40 years old AND
Unilateral swollen limb
Loss of plantar arch
Minimal pain
1. Painless in up to half of patients
Low mechanism injury (e.g. minor overuse or sprain)
1. No known preceding Trauma in up to half of patients

Warm, swollen, erythematous lower extremity (esp. over affected joints)
1. Erythema improves with elevation above heart level for 5-10 min (distinguish from infection)
Normal features that distinguish from other diagnoses
1. No fever
2. No open wound (unless complicated by Skin Ulcers)
3. Normal pulses

Identify Peripheral Neuropathy
1. Loss of Achilles Reflex
2. Monofilament Foot Sensation Test abnormal (poor Test Sensitivity)
Differentiate Osteomyelitis
1. See Suspected Osteomyelitis in Diabetes Mellitus
2. Probe To Bone Test (Described in Osteomyelitis)
Brodsky Test
1. Differentiates Charcot Stage 0 from Cellulitis
2. Technique
  1. Patient supine with involved leg raised 10 minutes
3. Interpretation
  1. Charcot Process: Swelling and erythema dissipate
  2. Infection: Swelling and erythema persist

Consider labs obtained in Osteomyelitis
Normal labs that distinguish from other diagnoses
1. Normal Complete Blood Count
2. Normal acute phase reactants (C-RP, ESR) unless infection (e.g. Osteomyelitis)

Precautions
1. Bony destruction may not be visible on xray for 6-12 months
Comparison bilateral weight bearing XRays
1. Evaluate for instability
  1. May appear as ligamentous avulsion Fractures (small avulsed bone fragments)
2. Evaluate for Osteomyelitis
Atrophic Neuroarthropathy (esp. midfoot)
1. Metatarsal heads have pencil point appearance
2. Midfoot Fractures are often missed
Consider additional testing for Osteomyelitis
1. See Suspected Osteomyelitis in Diabetes Mellitus

Charcot Foot is often misdiagnosed as an alternative condition with delayed diagnosis on average, 7 months
1. Consider in patients with recurrent "Cellulitis" (often improves transiently with bed rest)
Delayed diagnosis is a risk for rigid foot deformities with significant amputation risk (RR 15-40)
Involve specialty care early in course

Step 1 Immobilization
1. Total Contact Cast (TCC) or
2. Prefabricated pneumatic walking brace (PPWB)
Immobilize for 4 months until stable
1. Erythema and edema resolved
2. Affect limb with same Temperature as other limb
3. Stabilization by XRay (repeat every 4-6 weeks)
Step 2: Immobilize 6 to 24 months until foot stable
1. Charcot Restraint Orthotic Walker (CROW)
  1. Indicated for anterior edema
2. Ankle foot Orthosis
3. Patellar tendon-bearing brace
Step 3: Supportive Footwear
1. Extra-deep shoes with custom insoles
Additional treatment options
1. Exostosectomy
  1. Stable chronic Charcot Foot with exostosis or ulcer
2. TENS
3. Low intensity Ultrasound
4. Intranasal Calcitonin 200 IU (experimental)
  1. Bem (2006) Diabetes Care 29(6): 1392-4 [PubMed]
Other measures that are ineffective
1. Bisphosphonates
  1. Richard (2012) Diabetologia 55(5): 1258-64 +PMID:22361982 [PubMed]

Contraindications
1. Wagner Grade 3 Foot Ulcer (abscess or Osteomyelitis)
Technique
1. Tubular stockinette
2. One quarter inch felt
3. Three layer inner plastic shell
4. Fiberglass outer shell
Protocol
1. Crutch walking only
2. Initially change cast after first week (due to edema)
3. Later change cast every 2-4 weeks

Indications
1. Alternative to Total Contact Cast (above)
2. Neuropathic plantar ulcer
Contraindications
1. Severe foot deformity
2. Noncompliance

Rigid foot deformity
Below the knee Amputation
Foot Ulcer or plantar ulcer
1. High risk for infection and Osteomyelitis
2. Optimize foot wear to prevent Skin Ulcers
3. Chronic ulcers are associated with a 5 year mortality >50%
  1. Yammire (2022) Foot Ankle Surg 28(8): 1170-6 [PubMed]
Osteomyelitis
1. Surgical Debridement AND
2. Surgical correction of joint alignment and stability (Internal or external fixation)