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Diabetic Foot Ulcers

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Topic updated on 04/21/14 10:21am
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 more prone to injury due to drying 
    • angiopathy
      • lesser effect than neuropathy
      • >60% of diabetic ulcers have decreased blow 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 from bone
    • presence of infection
      • look for cellulities, 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
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 custum pneumatic walkers
      • patient compliance with offloading can be an issue because the pneumatic walker is removable

 

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Qbank (18 Questions)

TAG
(OBQ12.189) A 66-year-old male with a known history of uncontrolled Type 2 diabetes presents for follow up of a forefoot ulcer that is seen in Figure A. All of the following are strong prognostic indicators of osteomyelitis EXCEPT: Topic Review Topic
FIGURES: A          

1. Exposed bone at ulcer site
2. Periarticular erosions at 1st MTP joint
3. Increased signal within metatarsal diaphysis on T2 weighted MRI
4. Increased signal within indium labeled WBC scan
5. Positive wound culture

PREFERRED RESPONSE ▶
TAG
(OBQ11.151) A 55-year-old female with longstanding type I diabetes presents for evaluation of her left foot, which is shown in Figure A. On exam, the soft tissue infection extends to the metatarsals plantarly, and there is a palpable posterior tibial artery pulse. She is otherwise medically stable, and without sepsis. Which of the following treatment options will most likely result in definitive management of her forefoot gangrene and allow the highest level of functional activity after surgery? Topic Review Topic
FIGURES: A          

1. Transmetatarsal amputation
2. Below the knee amputation
3. Syme amputation
4. Above the knee amputation
5. Extensive soft-tissue debridement, local wound care, and antibiotic therapy

PREFERRED RESPONSE ▶
TAG
(OBQ10.81) A 44-year-old male with long standing insulin dependent diabetes complains of a non-healing plantar foot ulcer. The ulcer is shown in Figure A. The second metatarsal head can be probed at the base of the wound, and he lacks plantar sensation. Laboratory work-up for infection is negative. Which of the following is the best initial treatment? Topic Review Topic
FIGURES: A          

1. Ray resection and primary wound closure
2. Oral antibiotics and local wound care
3. Local wound care and non-weight bearing in a removable boot
4. Surgical debridement, dressing changes, and IV antibiotics
5. MRI of the foot to evaluate for underlying osteomyelitis

PREFERRED RESPONSE ▶
TAG
(OBQ10.150) A 65-year-old diabetic male presents with the foot ulcer shown in Figure A. There is no exposed bone, and no signs of infection. Pulses are palpable. What additional information should be obtained next to help guide this patient's treatment? Topic Review Topic
FIGURES: A          

1. MRI scan with contrast
2. Ankle-brachial index
3. Results of Silverskiold test
4. Transcutaneous oxygen measurements of the toes
5. Hemoglobin A1C level

PREFERRED RESPONSE ▶
TAG
(OBQ10.261) A 44-year-old man with diabetes mellitus has a non-healing Wagner grade 1 ulcer shown in Figure A for the past 8 months. Conservative management with total contact casting has not resolved the ulcer. Physical examination reveals loss of protective sensation by Semmes-Weinstein testing, no signs of infection, positive Silfverskiold test indicating gastrocnemius contracture, and palpable pedal pulses. What is the next most appropriate step in management? Topic Review Topic
FIGURES: A          

1. Integra artificial dermis placement followed by split thickness skin grafting
2. Continued total contact casting
3. Split thickness skin grafting to ulcer
4. Strayer procedure (gastrocnemius lengthening)
5. Weil metatarsal decompression osteotomy

PREFERRED RESPONSE ▶
TAG
(OBQ09.104) A 65-year-old patient with poorly controlled diabetes develops 2nd metatarsal head osteomyelitis deep to a superficial ulcer. Which nonoperative treatment modality would have the highest chance of success? Topic Review Topic

1. IV Vancomycin
2. Oral Levofloxacin
3. IV antibiotics based on ulcer swab culture sensitivity
4. IV antibiotics based on percutaneous bone biopsy culture sensitivity
5. Elevation and non-weight bearing

PREFERRED RESPONSE ▶
TAG
(OBQ09.130) A 57-year-old man taking metformin for diabetes and gabapentin for peripheral neuropathy has a superficial plantar midfoot ulcer with a clean, noninfected appearance. Total contact casting is implemented for mechanical relief. Which of the following radiographs most likely corresponds to the clinical situation described. Topic Review Topic
FIGURES: A   B   C   D   E  

1. Figure A
2. Figure B
3. Figure C
4. Figure D
5. Figure E

PREFERRED RESPONSE ▶
TAG
(OBQ09.271) You are caring for a 72-year-old male with diabetes and peripheral neuropathy with a non-healing forefoot ulcer as shown in Figure A. To reduce the plantar pressure on his forefoot, which of the following shoe modifications would you suggest? Topic Review Topic
FIGURES: A          

1. Polyethylene foam insole
2. Open toe sandles
3. Rocker sole shoes
4. Custom indepth shoes
5. Hard postoperative shoe

PREFERRED RESPONSE ▶
TAG
(OBQ07.90) A 45-year-old diabetic male has a Wagner type 3 heel ulcer shown in Figure A that measures 4x2cm and is recalcitrant to debridements and total contact casting for 4 months. The patient has palpable pulses, active drainage at the ulcer, and does not have protective sensation with a 5.07 Semmes-Weinstein filament. Radiograph and MRI (sagittal and axial) images are shown in Figures B-D respectively. In addition to bone culture biopsy, debridement and antibiotic therapy, what surgical intervention is most appropriate? Topic Review Topic
FIGURES: A   B   C   D    

1. Ankle disarticulation
2. Soft tissue fasciocutaneous flap coverage
3. Partial calcanectomy
4. Below knee amputation
5. Soft tissue free flap coverage

PREFERRED RESPONSE ▶
TAG
(OBQ07.125) Which of the following variables is not predictive of poor healing of diabetic foot ulcers? Topic Review Topic

1. Transcutaneous oxygen pressure < 20 mmHg
2. Systolic blood pressure > 140 mmHg
3. Ankle-brachial index < 0.45
4. Albumin < 3.0 g/dL
5. Total lymphocyte count < 1,500/mm3

PREFERRED RESPONSE ▶
TAG
(OBQ06.54) Which of the following patients with type 2 diabetes mellitus is most likely to develop a foot ulcer? Topic Review Topic

1. 54-year-old female unable to feel the presence of a 5.07 Semmes-Weinstein monofilament on the plantar aspect of the foot
2. 63-year-old male with transcutaneous oxygen pressures (TcpO2) of 30 mm Hg
3. 51-year-old male with ratio of ankle to brachial pressures of < 0.6
4. 71-year-old male with serum albumin of 3.1 g/dL
5. 60-year-old with autonomic dysfunction leads to drying of skin due to lack of normal glandular function

PREFERRED RESPONSE ▶
TAG
(OBQ06.117) Which of the following is not financially covered during one calendar year for Medicare patients under the United States Therapeutic Shoe Bill? Topic Review Topic

1. Three pair of inserts for extra-depth shoes
2. Shoe wedges
3. Inserts for missing toes
4. Two pairs of custom-molded shoes
5. Velcro closure shoe modification

PREFERRED RESPONSE ▶
TAG
(OBQ06.158) A 62-year-old diabetic female presents with a Wagner grade 1 foot ulcer. Upon examination of the foot, no dorsalis pedis pulse is palpable. Each of the following noninvasive vascular tests indicate a good prognosis for ulcer healing EXCEPT: Topic Review Topic

1. Triphasic waveforms
2. Ankle-brachial indices (ABI) of 0.72
3. Absolute toe pressure of 45 mm Hg
4. Transcutaneous oxygen measurements (pO2) of 15mm Hg
5. Presence of hair on the toes

PREFERRED RESPONSE ▶
TAG
(OBQ06.224) Which of the following is least likely to predict future amputation in diabetic patients? Topic Review Topic

1. Diabetic foot ulceration
2. Loss of sensation with 5.07 Semmes-Weinstein monofillament testing
3. Infection
4. Hemoglobin A1c level of 10.7
5. Ankle-brachial index of 1.07

PREFERRED RESPONSE ▶
TAG
(OBQ05.20) A 34-year-old patient is noted to have a lack of ankle dorsiflexion by 5 degrees with knee extension as seen in Figure A. However, the ankle dorsiflexion improves to 20 degrees with knee flexion as seen in Figure B. Which of the following diagnoses would benefit MOST from a gastrocnemius recession (Strayer procedure)? Topic Review Topic
FIGURES: A   B        

1. Chronic insertional achilles tendonitis
2. Freiberg's infraction
3. Chronic retrocalcaneal bursitis
4. Chronic calcaneal osteomyelitis
5. Chronic plantar forefoot ulcer

PREFERRED RESPONSE ▶
TAG
(OBQ04.84) A 37-year-old man with type-1 diabetes mellitus reports a 3-month history of a plantar foot ulcer shown in Figure A. His pulses are palpable and sensation to a 5.07 Semmes-Weinstein monofilament is absent on the entire plantar surface of the foot. There is no erythema or drainage and there is no bone encountered during probing of the ulcer. There is no fever and the white blood cell count is normal. The C-reactive protein and erythrocyte sedimentation rate are normal. What is the most appropriate next step in treatment? Topic Review Topic
FIGURES: A          

1. Total contact casting and empiric IV antibiotics
2. Surgical debridement, dressing changes, and empiric IV antibiotics
3. Charcot restraint orthotic walker (CROW)
4. Surgical debridement, dressing changes, biopsy, and culture specific IV antibiotics
5. Total contact casting

PREFERRED RESPONSE ▶



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