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Introduction
  • Ulceration in diabetic foot due to lack of protective sensation 
  • Epidemiology
    • incidence
      • approximately 12% of diabetics have foot ulcers
      • most common medical complication causing diabetics to get medical treatment
      • foot ulcers are responsible for ~85% of lower extremity amputations
    • risk factors
      • factors associated with decreased healing potential
        • uncontrolled hyperglycemia
        • inability to offload the affected area
        • poor circulation
        • infection
        • poor nutrition
      • factors associated with increased healing potential
        • serum albumin > 3.0 g/dL
        • total lymphocyte count > 1,500/mm3
  • Pathophysiology
    • neuropathy
      • has largest effect on diabetic foot pathology
      • sensory dysfunction leads to lack of protective sensation and is primary risk factor for ulcer development
      • autonomic dysfunction leads to drying of skin due to lack of normal glandular function
      • net effect is increased mechanical and axial stress on skin that is more prone to injury due to drying 
    • angiopathy
      • lesser effect than neuropathy
      • >60% of diabetic ulcers have decreased blood flow due to peripheral vascular disease
  • Associated conditions
    • infection / osteomyelitis
      • high rates of associated osteomyelitis if bone is able to be probed, or is exposed at the base of the ulcer   
        • 67% of ulcers that probe to bone have osteomyelitis 
      • organisms
        • usually polymicrobial
        • gram-positive
          • most common pathogens are aerobic gram positive cocci (s. aureus)
        • gram-negative
          • increased gram-negative organisms are found in chronic wounds and wounds recently treated with antibiotics
        • anaerobes
          • obligate anaerobic pathogens with ischemia or gangrene
      • deep cultures and bacterial biopsies help guide management
  • Prognosis
    • diabetic foot ulceration is considered the most likely predictor of eventual lower extremity amputation in patients with diabetes mellitus 
Classification
 
Wagner Classification and Treatment
 
Description
Treatment
Grade 0 Skin intact but bony deformities lead to "foot at risk" Shoe modifications with serial exams
Grade 1 Superficial ulcer Office debridement and contact casting
Grade 2 Deeper, full thickness extension Operative formal debridement and contact casting
Grade 3 Deep abscess formation or osteomyelitis Operative formal debridement and contact casting
Grade 4 Partial Gangrene of  forefoot Local vs. larger amputation
Grade 5 Extensive Gangrene Amputation
 
Brodsky Depth-Ischemia Classification and Treatment
Depth
Classification
Definition Treatment
At risk foot, no ulceration Patient education, accommodative footwear, regular clinical examination
1 Superficial ulceration, not infected Off-loading with total contact cast, walking brace or special footwear
2 Deep ulceration, exposing tendons or joints Surgical debridement, wound care, off-loading, culture-specific antibiotics
3 Extensive ulceration or abscess Debridement or partial amputation, off-loading, culture-specific antibiotics
Ischemia
A Not ischemic  
B Ischemia without gangrene Non-invasive vascular testing and vascular reconstruction with angioplasty/bypass
C Partial forefoot gangrene Vascular reconstruction and partial foot amputation
D Complete gangrene  Complete vascular evaluation and major extremity amputation 
 
Presentation
  • Symptoms
    • often painless
  • Physical exam
    • depth of ulcer
      • probe for bone
    • presence of infection
      • look for cellulitis, pus
      • check for gangrene
    • assess Achilles tendon tightness
      • Silverskiöld test 
        • improved ankle dorsiflexion with knee flexed = gastrocnemius tightness  
        • equivalent ankle dorsiflexion with knee flexion and extension = Achilles tightness
    • circulation
      • assess dorsalis pedis and posterior tibialis pulses
Studies
  • Transcutaneous oxygen pressures (TcpO2) 
    • considered Gold Standard to assess wound healing potential
    • > 30 mm Hg (or 40mmHg depending on review source cited) is a good sign of healing potential
  • ABI's and ischemic index
    • calcification in the arteries can result in inaccurate doppler flow readings 
      • calcifications falsely elevate the ABI's due to decreased compliance of the calcified vessels
      • index of > 0.45 and toe pressure >40mm Hg are needed to heal ulcer
Imaging
  • Radiographs
    • recommended views
      • AP, lateral, and oblique of foot and ankle
  • MRI
    • best for differentiating abscess from soft tissue swelling   
    • difficult to differentiate infection from Charcot arthropathy on MRI
  • Bone scan
    • views
      • obtain with technetium Tc99m, gallium (Ga)67, or indium (In) 111
    • useful to differentiate between
      • soft tissue infection
      • osteomyelitis
      • Charcot arthropathy
Treatment
  • General
    • factors important in deciding a treatment plan include
      • angiopathic vs. neuropathic
      • deep vs. superficial
      • +/- osteomyelitis, antibiotics based on bone biopsy culture sensitivities 
      • +/- pyarthrosis
  • Nonoperative
    • shoe modification
      • indications
        • prevention when signs of potential ulcers are present
      • includes deep or wide shoes, custom insoles, rocker bottom soles, etc.
      • of the available shoe only modifications, rocker sole shoes best reduce the plantar pressure on the forefoot 
      • medicare will cover modifications and custom shoes/insoles yearly 
    • wound care
      • indications
        • first line of treatment
      • goals of wound care and dressings
        • provide moist environment
        • absorb exudate
        • act as a barrier
        • off-load pressure at ulcer
    • total contact casting (TCC) 
      • indications
        • gold standard for mechanical relief plantar ulcerations  
      • contraindications
        • absolute
          • infection
        • relative
          • marginal arterial supply to affected area
          • patients unable to comply with cast care
          • patients unable to tolerate a cast (cast claustrophobia)
      • outcomes
        • if ulcer recurs, it is typically 3-4 weeks after cast removal 
  • Operative
    • surgical debridement, antibiotics, local wound care, contact casting 
      • indications
        • grade 3 or greater ulcers should undergo I&D with antibiotic treatment before casting
      • outcomes
        • high rates of associated osteomyelitis if bone is able to be probed, or is exposed at the base of the ulcer
    • ostectomy +/- TAL
      • indications
        • bony prominence causing internal pressure
      • technique
        • TAL indicated if tight Achilles    
          • several studies have shown TAL to be effective to help heal and prevent recurrence of plantar forefoot ulcers 
    • partial calcanectomy +/- TAL 
      • indications
        • large heel ulcers with associated calcaneal osteomyelitis
      • outcomes
        • preserves limb length and decreases morbidity compared to higher level amputations
    • Syme amputation 
      • indications
        • forefoot gangrene and a palpable posterior tibial artery pulse
    • Keller resection arthroplasty 
      • indications
        • IPJ plantar neuropathic ulcer with hypomobile/stiff MTPJ that has failed total contact casting
Techniques
  • Total Contact Casting
    • often necessary for up to 4 months
    • TCC followed by Charcot restraint walker then custom shoe
    • pneumatic walking brace
      • alternative to TCC, same principal
      • allows better wound surveillance
      • significant deformity and/or extremely large girth often requires custom pneumatic walkers
      • patient compliance with offloading can be an issue because the pneumatic walker is removable
 

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