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Introduction
  •  A chronic and progressive joint disease following loss of protective sensation
    • leads to destruction of joints and surrounding bony structures
    • may lead to amputation if left untreated
  • Epidemiology
    • incidence
      • 0.1-1.4% of patients with diabetes
      • 7.5% of patients with diabetes and neuropathy
    • demographics
      • age bracket
        • type 1 diabetes
          • typically presents in 5th decade (20-25 years following diagnosis)
        • type 2 diabetes
          • typically presents in 6th decade (5-10 years following diagnosis)
    • location
      • foot and ankle (diabetic Charcot foot)
        • 9-35% have bilateral disease
      • shoulder and elbow
      • knee  
        • often leads to ligamentous instability and bone loss
    • risk factors
      • diabetic neuropathy
      • alcoholism
      • leprosy
      • myelomeningocele
      • tabes dorsalis/syphilis
      • syringomyelia
  • Mechanism and pathophysiology
    • theories
      • neurotraumatic
        • insensate joints subjected to repetitive microtrauma
        • body unable to adopt protective mechanisms to compensate for microtrauma due to abnormal sensation
      • neurovascular
        • autonomic dysfunction increases blood flow through AV shunting
        • leads to bone resorption and weakening
    • molecular biology
      • inflammatory cytokines may cause destruction
        • IL-1 and TNF-alpha lead to increased production of
          • transcription factor-kB
          • RANK/RANKL/OPG triad pathway post
  • Associated conditions
    • orthopaedic manifestations
      • foot ulcerations
Classification
 
Brodsky Classification
Type 1  • Involves tarsometatarsal and naviculocuneiform joints
 • Collapse leads to fixed rocker-bottom foot with valgus angulation
60%
 
Type 2  • Involves subtalar, talonavicular or calcaneocuboid joints
 • Unstable, requires long periods of immobilization (up to 2 years) 
10%
 
Type 3A  • Involves tibiotalar joint
 • Late varus or valgus deformity produces ulceration and osteomyelitis of malleoli
20%
Type 3B  • Follows fracture of calcaneal tuberosity
 • Late deformity results in distal foot changes or proximal migration of the tuberosity
< 10%
Type 4  • Involves a combination of areas < 10%
Type 5  • Occurs solely within forefoot < 10%
 
Eichenholtz Classification
Stage 0
 • Joint edema
 • Radiographs are negative
 • Bone scan may be positive in all stages
  
Stage 1 fragmentation  • Joint edema
 • Radiographs show osseous fragmentation with joint dislocation 
  
Stage 2 coalescence  • Decreased local edema
 • Radiographs show coalescence of fragments and absorption of fine bone debris
  
Stage 3 reconstruction  • No local edema
 • Radiographs show consolidation and remodeling of fracture fragments
  

 

Presentation
  • Symptoms
    • swollen foot and ankle 
    • pain in 50%, painless in 50%
    • loss of function
  • Physical exam
    • acute Charcot neuropathy
      • inspection
        • swollen
        • warm
          • average of 3.3 degrees C warmer than contralateral side
        • erythema
          • often confused with infection
          • erythema will decrease with elevation in Charcot arthropathy, but is unchanged in infection
    • chronic Charcot neuropathy
      • inspection
        • structurally deformed foot
        • bony prominences
        • rocker bottom deformity
        • collapse of medial arch
      • motion
        • may be ligamentously unstable
      • neurovascular
        • Semmes-Weinstein monofilament testing
Imaging
  • Radiographs
    • views
      • obtain standard AP and lateral of foot, complete ankle series 
    • findings
      • early changes
        • degenerative changes may mimic osteoarthritis
      • late changes
        • obliteration of joint space
        • fragmentation of both articular surfaces of a joint leading to subluxation or dislocation
        • scattered "chunks" of bone in fibrous tissue
        • surrounding soft tissue edema
        • joint distension by fluid
        • heterotopic ossification
  • Bone scan
    • indications
      • useful to help determine presence of superimposed osteomyelitis
    • type of study
      • technetium bone scan
        • may be positive for a neuropathic joint and osteomyelitis
      • indium WBC scan
        • negative (cold) for neuropathic joints and positive (hot) for osteomyelitis
  • MRI
    • indications
      • best for differentiating abscess from soft-tissue swelling
      • most sensitive in diagnosing soft tissue and/or osteomyelitis
    • limitations
      • difficult to differentiate infection from Charcot arthropathy on MRI
Studies
  • Laboratory
    • inflammatory markers
      • ESR and WBC
        • elevated in both infection and Charcot arthropathy
    • wound healing levels
      • absolute lymphocyte count >1500/mm3
      • serum albumin >3.0g/dL
  • Biopsy
    • may be used to guide antibiotic therapy in cases of associated osteomyelitis or soft tissue abscess
  • Histology
    • synovial hypertrophy
    • detritic synovitis (cartilage and bone distributed in synovium)
Treatment
  • Nonoperative 
    • total contact casting, shoewear modifications, medications    
      • indications
        • first line of treatment
      • technique
        • contact casting
          • casts changed every 2-4 weeks for 2-4 months
        • orthotics
          • Charcot restraint orthotic walker (CROW) boot can be used after contact casting  
        • shoe modifications
          • in Eichenholtz stage 3 double rocker shoe modifications will best reduce risk for ulceration at the plantar apex of the deformity 
        • medications
          • bisphosphonates
          • neuropathic pain medications
          • antidepressants
          • topical anesthetics
      • outcomes
        • 75% success rate
  • Operative
    • resection of bony prominences (exostectomy) and TAL
      • indications
        • "braceable" foot with equinus deformity and focal bony prominences causing skin breakdown
      • technique 
        • goal is to achieve plantigrade foot that allows ambulation without skin compromise
    • deformity correction, arthrodesis +/- osteotomies  
      • indications
        • severe deformity that is not "braceable"
      • outcomes
        • very high complication rate (up to 70%)
    • amputations
      • indications
        • failed previous surgery (unstable arthrodesis)
        • recurrent infection
      • technique
        • goal is for a partial or limited amputation if vascularity allows
Surgical Techniques
  • Arthrodesis
    • technique
      • fixation techniques
        • internal fixation
          • screw, pins, plates, tibiocalcaneal nail
        • external fixation
          • used when bone quality is poor or soft tissues are compromised
    • post-operative care
      • minimal weight-bearing for three months
    • cons
      • high complication rate (up to 70%)
        • infection
        • hardware malposition
        • recurrent ulceration
        • fracture
 

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