Diabetic Foot Ulcer

Background

• A diabetic foot ulcer is an ulceration in the foot of a patient with diabetes as a consequence of neuropathy, pressure, and/or ischemia.
• Ulcers may be classified by degree of tissue involvement/depth, presence or absence of ischemia, and presence or absence of infection.
• Risk factors for diabetic foot ulcers include but are not limited to:
  • peripheral neuropathy (motor, sensory, or autonomic) (most common)
  • peripheral arterial disease
  • neuropathic arthropathy (also known as Charcot neuroarthropathy)
  • longer duration of diabetes (prevalence of peripheral neuropathy increases as the duration of the disease increases); however, in some patients, foot ulceration may be the presenting feature of type 2 diabetes
  • end-stage renal disease, particularly if dialysis is required
  • orthopedic abnormalities that alter biomechanics, resulting in areas of increased pressure on the foot
  • foot trauma
• Complications may include:
  • diabetic foot infection, including cellulitis
  • osteomyelitis (potential complication of any infected foot ulcer, especially if chronic)
  • sepsis
  • need for amputation

Evaluation

• Ulcers present as an open sore or wound on the foot. Common ulceration sites include the apex (tip) and plantar surfaces of the toes, plantar metatarsal head areas, and heel.
  • Due to sensory neuropathy (loss of protective sensation), patients may not recognize predisposing trauma to the foot, or realize the chronicity of their ulcers or the progressive signs of inflammation and infection.
  • In severe cases, bone involvement and gangrenous tissue changes can develop.
• Clinical evaluation of the foot should include a wound assessment, musculoskeletal evaluation, neurologic exam, and peripheral vascular exam to identify factors contributing to ulceration.
• Additional testing may include:
  • blood tests to assess glucose control and inflammation
    • Assess glucose control via measurement of:
      • fasting and/or patient’s home blood glucose monitoring and/or continuous glucose monitoring
      • HbA1c
    • Consider additional panels to measure inflammatory markers, including:
      • complete blood count
      • erythrocyte sedimentation rate
      • C-reactive protein
  • imaging studies to assess for infection in patients with ulcerations that fail to heal, progress in severity, or have clinical signs of infection (such as purulent secretions, redness, and warmth)
    • Plainx-ray is the initial imaging modality and may be sufficient for diagnosis, but maintain a low threshold for more advanced imaging modalities.
    • Consider magnetic resonance imaging (MRI) if x-ray results are equivocal and osteomyelitis is suspected (preferred over a computed tomography [CT] scan); however, MRI is not indicated if there are clear changes of osteomyelitis on a plain x-ray.
• Tissue culture is not indicated with clinically non-infected wounds. If infection is suggested by clinical exam:
  • a tissue sample obtained by incision or curettage of the wound bed should be sent to the laboratory post-debridement
  • do not perform superficial wound swabs
  • culture any obvious purulent drainage

Management

• General preventive measures for diabetic foot wounds includes good glycemic control, smoking cessation, use of proper footwear, inspecting feet daily, and being screened for neuropathy and vascular sufficiency with monofilament testing/other sensory tests and vascular exam annually.
• Optimal care may require referral to and consultation from a variety of specialties, including endocrinology, dermatology, podiatry, general surgery, vascular surgery, orthopedic surgery, plastic surgery, wound care, and psychology or social work.
• Patients with diabetic foot ulcers should receive appropriate wound care generally consisting of:
  • debridement aimed at removing necrotic or devitalized tissue (Strong recommendation)
    • first choice is surgical debridement (Strong recommendation)
    • enzymatic, mechanical, biological, or autolytic techniques may be appropriate for some wounds (Weak recommendation)
  • dressings that allow for moist wound healing and control excess exudation (Weak recommendation); dressings should be selected according to the state and morphology of the wound
  • "off-loading" (redistribution of pressure off wound to entire weight-bearing surface of foot) - especially important for plantar wounds and also necessary to relieve pressure caused by dressings, footwear, or walking (Strong recommendation)
    • A nonremovable, total contact cast is often considered the gold standard device (use with caution in patients with severe peripheral arterial disease or active infection where viewing or debridement of wound may be necessary).
    • Removable devices are available, but risk being removed by patients and not worn at home. Removable devices rendered irremovable appear to be as effective as standard total contact casting for facilitating wound healing.
  • corrective deformity surgery, including Achilles tendon lengthening (Weak recommendation) and various local surgical techniques (may help promote healing and prevent recurrence in select diabetic foot ulcers)
• Consider adjunctive therapy for selected diabetic foot wounds that are slow to heal, including negative-pressure wound therapy (Weak recommendation).
• Antimicrobial therapy for infected foot ulcers:
  • For mild infections, consider 1-2 weeks of therapy with an oral agent (Weak recommendation). Selection of the specific agent should be based upon the most likely infecting pathogen and guided by culture results (Strong recommendation).
  • For moderate-to-severe infections, consider empiric oral or IV antimicrobial therapy (based on clinical condition [severe infection usually indicates parenteral therapy]) with choice based on probable pathogen (Weak recommendation). Pathogen-directed therapy should follow, based upon culture and results of surgical consultation: oral antibiotics can usually be given at this stage (Strong recommendation).
• Most diabetic ulcers require many weeks to heal, and recurrence is common. Preventative education is indicated with any patient with a healing foot ulcer.