#42 The Diabetic Foot: Diagnose, prevent, and treat ulcers and infections

June 5, 2017 | By Matthew Watto, MD

Evaluate and treat the diabetic foot like international expert, Dr. Andrew Boulton, Professor of Medicine at the University of Manchester (England). From how to perform a proper foot exam, to foot care, to ulcers and infections we cover the essentials for your practice.

For full show notes visit http://thecurbsiders.com/podcast

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Clinical Pearls:

1. Inspect the diabetic foot at every visit!
2. History: Ask about symptoms of neuropathy, vascular claudication, foot deformity, and skin problems.
3. Diabetic foot care patient education: Inspect feet daily. Wash and dry daily with mild soap. Moisturize daily. Wear loose fitting cotton socks. Trim nail straight across. File down sharp edges. Never go barefoot. Avoid heels, open toed shoes, and sandals. Inspect inside of shoes before wearing.
4. Inspection: Note the hair pattern, skin findings like callus, presence or absence of sweat, nail abnormalities, and signs of infection.
5. Vascular exam: Pulses either absent or present. DON’T grade it! If abnormal then refer for ankle brachial index (ABI). If ABI abnormal (value <0.9) then refer to vascular surgery.
6. Neurologic exam: 10 gm monofilament plus either 128Hz tuning fork, pin prick, ankle reflex, or a fancy $$$ biothesiometer.
7. 10 gm monofilament: Demonstrate on proximal forearm 1st. Hold perpendicular to foot, apply pressure until filament bends. Hold for 1 second. Test at 1st, 3rd, 5th MTP head (plantar) and great toe. Loss of protective sensation (LOPS) present if absent sensation in any spot.
8. 128Hz tuning fork: Large fork with round heads. Apply to tip of great toe. Abnormal if examiner senses vibration and patient cannot.
9. MSK exam: Observe for deformity and intrinsic muscle wasting e.g. classic claw foot (extension at metatarsophalangeal (MTP) joints with flexion deformity at proximal interphalangeal joint).
10. Pathophysiology diabetic foot ulcers: Autonomic neuropathy leads to absent sweat. Skin becomes dry and cracks. Lack of autonomic vascular tone in microvasculature causes arterial to venous shunting, bypassing tissues and causing poor nutrition, local ischemia/injury. On exam veins are distended and pulses bounding. Wasting of intrinsic foot muscles causes claw foot with abnormal pressure on MTP joints and pads of toes. Dry skin with poor nutrition and foot deformity puts foot at risk for injury, infection, and skin breakdown.
11. Diabetic foot ulcer (DFU): Remove callus (like a rock in the shoe). Use sharp debridement down to healthy bleeding tissue, then off load with cast or boot to offload the wound. Removable casts have inferior results due to poor compliance. Antibiotics not needed for non-infected ulcers (no erythema, tenderness, swelling, warmth, exudate).
12. Diabetic foot infection (DFI) diagnosis: Clinical assessment for signs of infection (erythema, tenderness, swelling, warmth, exudate). Debride the wound then swab or biopsy the wound bed. Biopsy bone if visible, or suspected diabetic foot osteomyelitis (DFO). Serial plain films are test of choice, but DFO lags up to two weeks before seen on xray. Consider ESR, CRP (helpful if sky high).
13. DFI therapy: For mild DFI: Treat 10-14 days with dicloxacillin, clindamycin, or amoxicillin/clavulanic acid plus refer to podiatry (or surgery, or wound care specialist, or vascular surgeon*) for debridement. Consider doxycycline, or trimethoprim-sulfamethoxazole if MRSA risk (use link to IDSA below). *Vascular surgery consult warranted if peripheral arterial disease present e.g. abnormal ABI. For moderate to severe DFI: initial IV therapy and hospitalization may be needed (see IDSA 2012 below).
14. DFO therapy: RCT from Spain states localized DFO responds well to abx alone (usually 6 weeks). If more extensive (e.g. septic arthritis), then likely need surgical source control.

Goal: Listeners will recognize the “at risk diabetic foot” and initiate therapy for common complications.

Learning objectives:
By the end of this podcast listeners will:

1. Explain the pathophysiology of diabetic foot ulcers
2. Recall the key parts to the diabetic foot exam
3. Utilize 10gm monofilament and 128Hz tuning fork to evaluate sensation
4. Evaluate the diabetic foot for autonomic neuropathy
5. Evaluate the diabetic foot for vascular disease
6. Employ basic management for diabetic foot ulcers
7. Treat mild diabetic foot infections
8. Diagnose diabetic foot osteomyelitis
9. Counsel patients on appropriate foot care

Disclosures:
N/A

Time Stamps
00:00 Intro
03:40 Picks of the week
08:36 The diabetic foot exam
10:35 How to explain diabetic neuropathy
12:00 Treatment of diabetic foot ulcers
16:39 Diabetic foot infections
19:10 Monitoring and duration of antibiotic therapy
21:49 Case of a diabetic foot gone bad
23:57 Take home points
25:55 Curbsiders take home points
27:30 How to exam the diabetic foot
29:40 Neuro exam
33:50 Pulse exam
35:30 Pathophysiology reviewed
38:15 How to counsel patients about foot care
43:28 Outro

Links from the show:

1. Diabetic Foot Exam form share with permission from Dr. Jeffrey Colburn and the Diabetes Center of Excellence at Wilford Hall Ambulatory Surgical Center
2. Khan Academy review of atherosclerosis
3. Diabetic Foot Exam video from YouTube by the Indian Health Service.
4. Miller JD et al. How to do a 3-minute diabetic foot exam. J Fam Pract. 2014 Nov;63(11):646-56.
5. American Association of Physician Leadership. “The Value of Physician Leadership” 2014 PDF or https://www.ncbi.nlm.nih.gov/pubmed/24964545
6. Removable cast made irremovable study by Dr. Boulton Diabetes Care 2005
7. Removable cast versus irremovable cast study by Dr. Armstrong Diabetes Care 2005
8. IDSA Guidelines for the Diagnosis and Treatment of Diabetic Foot Infections. Clinical Infectious Diseases;2012 ; 54 : 132 -173.
9. Diabetic foot care tips from WebMD
10. Microvascular Complications and Foot Care  American Diabetes Association Diabetes Care 2017 Jan; 40(Supplement 1): S88-S98. https://doi.org/10.2337/dc17-S013
11. Boulton, A et al. Comprehensive Foot Examination and Risk Assessment A report of the Task Force of the Foot Care Interest Group of the American Diabetes Association, with endorsement by the American Association of Clinical Endocrinologists. Diabetes Care 2008 Aug; 31(8): 1679-1685. https://doi.org/10.2337/dc08-9021
12. http://www.mdedge.com/jfponline/article/88218/diabetes/how-do-3-minute-diabetic-foot-exam/pdf