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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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Questions (17)

(OBQ13.130) A diabetic ulcer shown in Figure A probes down to bone when a cotton-tipped applicator is used. What is the approximate likelihood this patient has osteomyelitis? Review Topic

QID:4765
FIGURES:
1

5%

0%

(9/2752)

2

25%

2%

(60/2752)

3

35%

3%

(90/2752)

4

65%

56%

(1542/2752)

5

100%

38%

(1041/2752)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

When bone is probed in a diabetic ulcer, the likelihood of osteomyelitis being present is between 60-70%.

Diabetic ulcers are the most common reason that diabetic patients seek medical treatment. If bone is exposed or can be palpated, there is a 67% chance of osteomyelitis being present. The osteomyelitis is usually polymicrobial in nature, with Staphylococcus aureus being the most common pathogen. The presence of ulceration is the most predictive factor for eventual amputation in diabetic patients.

Lavery et al. measured the accuracy of the probe-to-bone (PTB) test to diagnose osteomyelitis. They found that the PTB test had a positive predictive value of 57%, the sensitivity and specificity being higher.

Grayson et al. evaluated foot ulcers to identify the presence of osteomyelitis. When osteomyelitis was diagnosed in 50 cases, bone was probed in 66% of these cases. They concluded that probing to bone was strongly correlated with the presence of osteomyelitis. If bone is palpated, the additional confirmatory tests are unnecessary.

Pinzur et al. provide guidelines for management of diabetic feet. They note that the screening examination should include evaluation for neuropathy, the presence of ulcers or wounds and vasculopathy. Ulcers should be treated with debridement as necessary, dressings and off-loading.

Figure A shows a plantar diabetic ulcer adjacent to the second metatarsal.

Incorrect Answers
Answers 1, 2, 3, 5: The probe-to-bone test demonstrates a likelihood of osteomyelitis of close to 70%.


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(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: Review Topic

QID:4549
FIGURES:
1

Exposed bone at ulcer site

3%

(82/2811)

2

Periarticular erosions at 1st MTP joint

12%

(343/2811)

3

Increased signal within metatarsal diaphysis on T2 weighted MRI

4%

(117/2811)

4

Increased signal within indium labeled WBC scan

3%

(87/2811)

5

Positive wound culture

77%

(2159/2811)

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

All of the variables listed are consistent with osteomyelitis in diabetic foot ulcers EXCEPT for a positive wound culture. These are often positive in all stages of a diabetic foot ulcer, even when osteomyelitis is not present.

Diabetic ulcers are a common medical complication in those with diabetics, with an approximate incidence of 12%. The presence of a diabetic ulcer is the biggest predictor of eventual lower extremity amputation. Ulcers that probe down to bone are associated with underlying osteomyelitis ~ 70% of the time. Risk factors that implicate a poor healing prognosis are a lymphocyte count < 1500, an albumin < 3.5, ABI < 0.45 and transcutaneous oxygenation pressures < 20-30 mm Hg.

Armstrong et al. provide an overview of the evaluation and management of diabetic ulcers. They describe that the most common risk factors for ulcer formation include neuropathy, structural deformity and vasculopathy. It is important to perform an adequate physical examination, including monofilament testing, to delineate those at risk for development of ulcers and to stratify those with ulcers. Patient education is also critical.

Shank et al. provide a review of the osteomyelitis of in the diabetic foot. They indicate that ulcers with exposed bone can be presumed to have osteomyelitis. MRI can be used for preoperative planning. A tagged WBC scan may be useful in cases, like Charcot arthropathy, where the diagnosis is not as clear. Broad spectrum antibiotics should be included in treatment regimens, while surgical intervention is warranted for severe infections, or when there is evidence of ischemia or sepsis.

Figure A demonstrates a forefoot ulcer in the tripod region of the foot (1st MT head). Because of the forces that the forefoot normally experiences, this is a common area for diabetic ulcers to develop.

Incorrect Answers:
Answers 1: Bony exposure at the ulcer site is highly predictive of the presence of osteomyelitis.
Answer 2: Periarticular erosions at the level of the metatarsal head are often seen in osteomyelitis.
Answers 3, 4: Increased signal on MRI and on an Indium-labeled WBC bone scan are consistent with a diagnosis of osteomyelitis.


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(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? Review Topic

QID:3574
FIGURES:
1

Transmetatarsal amputation

19%

(352/1820)

2

Below the knee amputation

7%

(130/1820)

3

Syme amputation

73%

(1321/1820)

4

Above the knee amputation

0%

(3/1820)

5

Extensive soft-tissue debridement, local wound care, and antibiotic therapy

1%

(13/1820)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

Isolated forefoot gangrene in the presence of a palpable posterior tibial artery pulse can be definitively managed with a Syme amputation, which leads to a relatively high functional status in these patients. A Syme amputation includes ankle disarticulation, removal of malleoli, and anchoring heel pad to the weight bearing surface. A viable heel pad is critical for surgical success of a Syme amputation, and it receives its blood supply from branches of the posterior tibial artery. An example of this post-operatively is shown in Illustration A.

Francis et al reviewed the charts of 26 dysvascular patients with forefoot necrosis who underwent Syme amputation. They found that 85% of the patients with a palpable posterior tibial pulse had a successful amputation in contrast to one out of four who did not have a palpable pulse before surgery. They concluded that the single most important feature for success with Syme amputations is to limit the operation to those patients with a palpable posterior tibial pulse before surgery.

Laughlin et al reviewed the surgical results and functional outcome of 52 patients treated with Syme amputations for forefoot gangrene. They found that 90% of the patients who had a posterior tibial artery with either a triphasic waveform or a normal pulse achieved a healed wound suitable for prosthetic wear after undergoing a Syme amputation. This is compared to only a 57% success rate in patients with compromised posterior tibial arterial flow.

Incorrect Answers:
1-A transmetatarsal amputation may be used initially to clear an infection before completing a more proximal amputation. However, this would not be appropriate as definitive management due to its proximity to the infected and necrotic tissue distally.
2,4-An above or below knee amputation in the presence of a palpable posterior tibial artery would not be appropriate as significantly better functional results result from a more distal Syme amputation.
5-Soft tissue debridement, local wound care, and antibiotic therapy would not definitively treat forefoot gangrene.

ILLUSTRATIONS:

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(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? Review Topic

QID:3169
FIGURES:
1

Ray resection and primary wound closure

2%

(31/1442)

2

Oral antibiotics and local wound care

1%

(18/1442)

3

Local wound care and non-weight bearing in a removable boot

19%

(269/1442)

4

Surgical debridement, dressing changes, and IV antibiotics

55%

(799/1442)

5

MRI of the foot to evaluate for underlying osteomyelitis

22%

(323/1442)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

The wound described and shown in this question would be classified as a Wagner Grade 3 ulcer due to the presence of exposed bone. The ability to probe bone at the base of the ulcer is indicative of underlying osteomyelitis and this should be initially treated with surgical debridement, IV antibiotics and local wound care.

Pinzur et al provide an overview of diabetic foot care and address physical examination, patient education, and basic treatment guidelines.

Grayson et al evaluated 76 foot ulcers and found that palpating bone on probing the pedal ulcer had a sensitivity of 66% for osteomyelitis, a specificity of 85%, and should be should be included in the initial assessment of all diabetic patients with infected pedal ulcers.

Incorrect Answers:

Answer 1: Ray resection or partial foot amputation could be considered in this case, however this is usually reserved for patients who have failed local treatment or are systemically ill from their ulcer.
Answer 2 & 3: Oral antibiotics or boot application are not an aggressive enough treatment option in this clinical scenario, and are more appropriate treatment options for Wagner grade 1 ulcers.
Answer 5: Underlying osteomyelitis should be assumed to be present in this case; therefore, an MRI is not useful in guiding treatment at this stage.


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(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? Review Topic

QID:3238
FIGURES:
1

MRI scan with contrast

5%

(100/2073)

2

Ankle-brachial index

12%

(239/2073)

3

Results of Silverskiold test

57%

(1185/2073)

4

Transcutaneous oxygen measurements of the toes

19%

(387/2073)

5

Hemoglobin A1C level

8%

(158/2073)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

Forefoot ulcers are exacerbated by a fixed plantarflexion contracture secondary to either a tight Achilles or gastrocnemius tendon. The Silfverskiold test differentiates isolated contractures of the gastrocnemius from the gastrocsoleus complex. The forefoot is inverted and the hind foot is positioned in subtalar neutral to lock the transverse tarsal joints. The knee is first flexed with ankle dorsiflexion and then compared to passive motion with the knee extended. Illustration A shows a positive test with equinus contracture In the presence of palpable pulses and a plantarflexion contracture.

Wagner grade 1 and 2 ulcers (abscence of osteomyelitis) should be treated with total contact casting AND gastrocnemius recession when indicated to decrease the risk of ulcer recurrence. An MRI scan with contrast would be helpful if there was concern for infection. Ankle-brachial index and transcutaneous oxygen measurements should be performed in the absence of palpable pulses. HgbA1C levels are useful in guiding the chronic management of diabetes and should be optimized. However, it is less useful in the acute management of a plantar ulcer.

Lin et al looked at 93 neuropathic diabetes mellitus patients with foot ulcers who underwent a total contact cast protocol. Fifteen of the patients showed delayed ulcer healing and all were noted to have an ankle equinus deformity and limited joint motion. This group was treated with percutaneous tendo-Achilles lengthening, and all but one ulcer went on to heal.

Mueller et al randomized 64 subjects into two treatment groups, immobilization in a total-contact cast alone or combined with percutaneous Achilles tendon lengthening. All ulcers healed in the Achilles tendon lengthening group, and the risk for ulcer recurrence was 75% less at seven months and 52% less at two years than the risk of recurrence in the total-contact cast alone group.

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(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? Review Topic

QID:3358
FIGURES:
1

Integra artificial dermis placement followed by split thickness skin grafting

2%

(33/2190)

2

Continued total contact casting

2%

(42/2190)

3

Split thickness skin grafting to ulcer

1%

(13/2190)

4

Strayer procedure (gastrocnemius lengthening)

92%

(2014/2190)

5

Weil metatarsal decompression osteotomy

4%

(82/2190)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

Diabetic forefoot ulcers can be refractory to conservative management due to a fixed plantarflexion contracture and can be corrected with a Strayer procedure.

The Silverskiold test differentiates isolated contractures of the gastrocnemius from the gastrocsoleus complex. The forefoot is inverted and the hind foot is positioned in subtalar neutral to lock the transverse tarsal joints. The knee is first flexed with ankle dorsiflexion and then compared to passive motion with the knee extended. Isolated gastrocnemius contracture is present if dorsiflexion is increased during knee flexion compared to knee extension and indicates that an isolated gastrocnemius fascia lengthening (Strayer procedure) is sufficient. If there is an equinus contracture that does not improve with knee flexion then the entire gastrocsoleus complex is contracted and an achilles tendon lengthening (Hoke procedure) is required and not an isolated gastrocnemius facia lengthening (Strayer procedure).

Mueller et al randomized 64 subjects into two treatment groups, immobilization in a total-contact cast alone or combined with percutaneous Achilles tendon lengthening. All ulcers healed in the Achilles tendon lengthening group, and the risk for ulcer recurrence was 52% less at 2 years compared to treatment with total-contact casting alone.

Lin et al evaluated 93 neuropathic diabetic patients with foot ulcers who underwent conservative management. Fifteen of the patients showed delayed ulcer healing and all were noted to have an ankle plantarflexion contracture. This group was treated with percutaneous tendo-Achilles lengthening, and 14 went on to heal the ulcer.


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(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? Review Topic

QID:2917
1

IV Vancomycin

1%

(25/1914)

2

Oral Levofloxacin

0%

(6/1914)

3

IV antibiotics based on ulcer swab culture sensitivity

2%

(30/1914)

4

IV antibiotics based on percutaneous bone biopsy culture sensitivity

94%

(1805/1914)

5

Elevation and non-weight bearing

2%

(42/1914)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

Intravenous antibiotics tailored to bone biopsy culture sensitivities have the best chance of successful treatment of foot osteomyelitis in diabetics. A multi-center retrospective review by Senneville et al. demonstrated only (64%) remission of foot osteomyelitis in diabetics at one year. Antibiotic tailored by bone biopsy culture sensitivities was the only factor that significantly affected remission rates of osteomyelitis.

Authors:

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(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? Review Topic

QID:2943
FIGURES:
1

Figure A

0%

(5/1316)

2

Figure B

1%

(14/1316)

3

Figure C

73%

(963/1316)

4

Figure D

8%

(102/1316)

5

Figure E

17%

(227/1316)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

This diabetic patient with a plantar midfoot ulcer most likely has Charcot arthropathy of the foot. This is shown radiographically in Figure C as evident by the midfoot destruction and joint subluxation. Charcot arthropathy occures in 7.5% of neuropathic diabetics.

Wukich et al described an 83% rate of ulcer healing with total contact casting in neuropathic ulcers and noted a 17% rate of complications (most being due to skin irritation from the cast).

Figure A shows a homolateral Lisfranc injury and Figure B shows a hallux valgus deformity. Figure D shows a radiograph of a cavus foot often associated with Charcot Marie Tooth disease. Figure E shows a radiograph of an acquired flatfoot deformity with midfoot subluxation but there is absent fragmentation, osteopenia, or bony destruction indicating Charcot arthropathy of the foot.


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(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? Review Topic

QID:3084
FIGURES:
1

Polyethylene foam insole

5%

(66/1255)

2

Open toe sandals

0%

(1/1255)

3

Rocker sole shoes

71%

(894/1255)

4

Custom indepth shoes

22%

(278/1255)

5

Hard postoperative shoe

1%

(13/1255)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

The rocker sole best reduces forefoot plantar pressure.

Brown et al. examined the effect of different rocker soles on plantar pressure in 40 patients without foot deformities by measuring the plantar pressures over a 400 step course. All 3 rocker designs showed a significant reduction in peak pressure and the pressure time integral.

Janisse and Janisse review the various shoe modifications in the nonoperative treatment of foot and ankle pathology, and review the treatment options regarding rocker sole shoes, and other shoe modifications.


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(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? Review Topic

QID:751
FIGURES:
1

Ankle disarticulation

5%

(84/1826)

2

Soft tissue fasciocutaneous flap coverage

5%

(87/1826)

3

Partial calcanectomy

76%

(1395/1826)

4

Below knee amputation

10%

(188/1826)

5

Soft tissue free flap coverage

4%

(67/1826)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

This patient has failed conservative management and has evidence of osteomyelitis on MRI. Intravenous antibiotics tailored to bone culture biopsy sensitivities have the best chance of successful treatment of foot osteomyelitis in diabetics.

A partial calcanectomy would be the next most appropriate step in management if debridement was not sufficient. Partial or complete calcanectomy are preferred over higher level amputations such as Syme ankle disarticulations and transtibial amputations to preserve limb length and decrease morbidity. Soft tissue coverage can be appropriate for ulcers in the absence of infection and higher level amputations would be more appropriate if there was evidence of a dysvascular limb or inability to heal the ulcer once the tissues are free of infection.

Smith et al reviewed 12 patients with large heel ulcers and calcaneal osteomyelitis and found the wound healed after partial calcanectomy in ten of the twelve patients. They note that the Achilles must be released and allowed to retract proximally since the posterior process of the calcaneus is removed, with the cut starting one centimeter posterior to the edge of the subtalar and calcaneocuboid joints. A custom molded orthosis is needed postoperatively to help cushion the heel during ambulation.

Illustration A depicts a proposed line of resection for a partial calcanectomy as described by Smith et al. Illustration B shows a full listing of the Wagner classification.

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

QID:786
1

Transcutaneous oxygen pressure < 20 mmHg

2%

(26/1331)

2

Systolic blood pressure > 140 mmHg

91%

(1209/1331)

3

Ankle-brachial index < 0.45

1%

(14/1331)

4

Albumin < 3.0 g/dL

1%

(12/1331)

5

Total lymphocyte count < 1,500/mm3

5%

(67/1331)

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

In evaluation of a non-healing diabetic foot ulcer the patient's capacity for healing can be assessed with several methods. Vascular evaluation begins with noninvasive testing that includes an ankle-brachial index(ABI) and transcutaneous oxygen pressure. An ABI of < 0.45 or transcutaneous oxygen pressure of <30 mmHg (or 40mmHg depending on review source cited) are negative predictors of healing. Laboratory studies help assess immunity and overall nutrition. An albumin of <3.0 g/dL or a total lymphocyte count of < 1,500/mm3 are negative predictors of healing. Systolic blood pressure has not been shown to be predictive.


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

QID:165
1

54-year-old female unable to feel the presence of a 5.07 Semmes-Weinstein monofilament on the plantar aspect of the foot

77%

(367/475)

2

63-year-old male with transcutaneous oxygen pressures (TcpO2) of 30 mm Hg

4%

(19/475)

3

51-year-old male with ratio of ankle to brachial pressures of < 0.6

15%

(69/475)

4

71-year-old male with serum albumin of 3.1 g/dL

0%

(2/475)

5

60-year-old with autonomic dysfunction leads to drying of skin due to lack of normal glandular function

3%

(15/475)

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

The primary risk factor for the development of a diabetic foot ulcer is loss of protective sensation and this is commonly tested with a 5.07 Semmes-Weinstein monofilament. Once an ulcer is present, non-invasive vascular evaluation is performed to determine ulcer healing potential via ankle-brachial index(ABI) or transcutaneous oxygen pressure (TcpO2).

An ABI of < 0.45 or transcutaneous oxygen pressure of <30 mmHg (or 40mmHg depending on review source cited) are negative predictors of healing. Laboratory studies help assess immunity and overall nutrition. An albumin of < 3.0 g/dL or a total lymphocyte count of < 1,500/mm3 are negative predictors of diabetic ulcer healing. Foot ulcers are considered the most likely predictor of eventual lower extremity amputation in patients with diabetes mellitus.


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

QID:303
1

Three pair of inserts for extra-depth shoes

28%

(103/364)

2

Shoe wedges

7%

(25/364)

3

Inserts for missing toes

9%

(34/364)

4

Two pairs of custom-molded shoes

47%

(170/364)

5

Velcro closure shoe modification

8%

(30/364)

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PREFERRED RESPONSE 4

All of the items listed above are covered by the United States Therapeutic Shoe Bill EXCEPT option 4, as only 1 pair of custom-molded shoes are approved per year.

Diabetes results in a 15 to 40 fold increased risk of amputation. An estimated 67,000 diabetes related amputations occur in the U.S. each year. For this reason, certain orthotics are provided as a part of medicare coverage under the Therapeutic Shoe Bill (TSB).

Janisse presents a review article describing that The Therapeutic Shoe Bill (TSB) covers 4 things: Custom-molded shoes, Depth shoes (3/16 inch extra depth minimum), inserts, & shoe modifications (ie: rocker soles, metatarsal bars, wedges, flared heels, Velcro closures, and inserts for missing toes). The TSB provides coverage for one of the following within one calendar year: One pair of custom-molded shoes (including one pair of inserts provided with such shoes) and two additional pairs of inserts; or one pair of extra depth shoes and three pairs of inserts.


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(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: Review Topic

QID:344
1

Triphasic waveforms

1%

(8/706)

2

Ankle-brachial indices (ABI) of 0.72

28%

(197/706)

3

Absolute toe pressure of 45 mm Hg

2%

(16/706)

4

Transcutaneous oxygen measurements (pO2) of 15mm Hg

66%

(466/706)

5

Presence of hair on the toes

2%

(16/706)

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PREFERRED RESPONSE 4

Approximately 60-70% of patients who have had diabetes for over 10 years have evidence of peripheral vascular disease. Vascular examination of the diabetic foot includes evaluating for the presence of dorsalis pedis and posterior tibial artery pulses. The absence of hair on the foot is an additional indicator of compromised blood flow. Transcutaneous oxygen measurements >30 mm Hg (this estimate varies through textbooks from 30-40mmhg) indicates that blood flow is adequate for healing. An ABI =0.45 is needed to heal an ulcer in the diabetic foot. It is important to note that peripheral vascular calcifications can falsely elevate ABI results, thus reducing the sensitivity of ABI's as a screening test. Toe pressures >40 mm Hg have been associated with ulcer healing.

The article by Wagner is a review article discussing the evaluation of foot vascularity and establishing the Wagner classification of foot ulcers. The ulcers are categorized into six grades ranging from grade zero to grade five as seen in Illustration A. The grade is determined based on depth of the skin lesion and the presence or absence of infection and gangrene. A Wagner 1 ulcer as found in this case is a superficial or full thickness ulcer that does not expose ligaments, deep fascia, or bone.

ILLUSTRATIONS:

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

QID:235
1

Diabetic foot ulceration

4%

(19/487)

2

Loss of sensation with 5.07 Semmes-Weinstein monofillament testing

5%

(22/487)

3

Infection

2%

(9/487)

4

Hemoglobin A1c level of 10.7

2%

(12/487)

5

Ankle-brachial index of 1.07

87%

(425/487)

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PREFERRED RESPONSE 5

The references state that diabetic patients who underwent amputations also had these concurrent variables: ulceration 84%, neuropathy 64%, infection 59%, gangrene 55%, and ischemia 46%.

Other risk factors factors included elevated hemoglobin A1c level, decreased oxygen tension levels, and a decreased ankle-brachial index.


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(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)? Review Topic

QID:57
FIGURES:
1

Chronic insertional achilles tendonitis

14%

(186/1341)

2

Freiberg's infraction

3%

(35/1341)

3

Chronic retrocalcaneal bursitis

3%

(44/1341)

4

Chronic calcaneal osteomyelitis

1%

(14/1341)

5

Chronic plantar forefoot ulcer

79%

(1056/1341)

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PREFERRED RESPONSE 5

This patient has a positive Silverskiold test. The Silfverskiold test differentiates isolated contractures of the gastrocnemius from the gastrocsoleus complex. The forefoot is inverted and the hind foot is positioned in subtalar neutral to lock the transverse tarsal joints. The knee is first flexed with ankle dorsiflexion and then compared to passive ankle dorsiflexion with the knee extended. Isolated gastrocnemius contracture is present if dorsiflexion is increased during knee flexion compared to knee extension and indicates that an isolated gastrocnemius fascia lengthening (Strayer procedure) is sufficient. If there is an equinus contracture that does not improve with knee flexion then the entire gastrocsoleus complex is contracted and an achilles tendon lengthening (Hoke procedure) is required.

The study by Armstrong et al found that a percutaneous achilles tendon lengthening led to a 25% decrease in contact peak pressure over the metatarsal heads in 10 diabetic patients with prior ulceration and high risk for reulceration.

AAOS Comprehensive Orthopaedic Review additionally states that "lengthening can be helpful in reducing plantar forefoot pressure" and ostectomy or realignment arthrodeses can also be helpful in managing deformities associated with diabetic foot ulcers.


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(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? Review Topic

QID:1189
FIGURES:
1

Total contact casting and empiric IV antibiotics

3%

(23/858)

2

Surgical debridement, dressing changes, and empiric IV antibiotics

3%

(30/858)

3

Charcot restraint orthotic walker (CROW)

5%

(41/858)

4

Surgical debridement, dressing changes, biopsy, and culture specific IV antibiotics

7%

(58/858)

5

Total contact casting

82%

(704/858)

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PREFERRED RESPONSE 5

Total contact casting is an effective therapy for healing chronic neuropathic plantar ulcers in individuals with diabetes mellitus and other chronic sensory neuropathies. There is no sign of clinical infection present so surgical debridement and antibiotics are not indicated. Total contact casts are snug-fitting, below-knee casts that protect insensate limbs from repetitive trauma, promote ulcer healing, and allow the patient to remain ambulatory status. Most ulcers recur within the first 6 months (typically within the 1st month) after initial healing. When the active disease phase is finished, the patient can be given a Charcot restraint orthotic walker (CROW), and then fitted with a custom shoe/orthotic.


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