Treatment of the Diabetic Foot

Essentials

• Diabetes predisposes the patient to foot deformities, infections and ulcers.
• The most significant causes of foot problems are neuropathy Diabetic Neuropathy and ischaemia Lower Limb Ischaemia associated with external injury.
• Follow-up and early treatment prevent complications and amputation. Even minor skin injuries should be treated without delay.
• A total-contact cast, therapeutic shoe or other offloading will help to treat chronic ulcers Treatment of Lower Extremity Ulcers.
• Critical ischaemia Lower Limb Ischaemia should be recognized and treated immediately with vascular surgery.
• An erythematous, hot and swollen foot in a patient with diabetes must be considered Charcot's foot until otherwise proven.

Examination of feet

• The feet should be examined at least once a year, particularly in patients with type 2 diabetes and in patients with type 1 diabetes aged more than 30 years whose disease has been present for more than 15 years.
• The examination can be performed by a chiropodist/podiatrist or a diabetes nurse specialist.
• Poor glucose control, target organ damage, smoking, alcohol consumption, poor hygiene and mental problems predispose to foot problems.
• Padding and positioning should be used to prevent the development of pressure ulcers in bedridden patients with diabetes. The skin should be checked daily.
• Risk classification T1 helps to direct special attention and interventions to those who will benefit most (risk category 2-3).
• The WIfI (Wound, Ischemia, and foot Infection) classification correlates with important clinical end points such as preservation of the extremity and healing of the ulcer http://iwgdfguidelines.org/wp-content/uploads/2019/05/IWGDF-Guidelines-2019.pdf.

• Neuropathy
  • Symptoms of sensory neuropathy include tingling, numbness, cramps, “restlessness”, lack of sensation, pain, and hyperaesthesia in the feet.
  • Weakened sense of touch (monofilament test, see picture 1), disappearance of the sense of vibration (128 Hz) , and absence of the Achilles tendon reflexes are the most easily recognized signs of neuropathy Diabetic Neuropathy.
• Circulation
  • Claudication, pain at rest, history of vascular surgery Lower Limb Ischaemia?
  • Cold feet and thin, shiny and erythematous or cyanotic skin suggest poor arterial blood flow.
  • If palpation of ankle pulses is uncertain, measure the ABI (see Doppler Stethoscopy in Diagnostics).
    • An ABI below 0.9 suggests occlusive arterial disease.
    • An ABI exceeding 1.4 suggests stiffening of the arterial wall due to media sclerosis, which may give erroneously high and unreliable ankle pressure readings (if so, toe pressure should be measured in specialized care).
    • Ankle pressure below 50 mmHg or, in case of tissue damage, below 70 mmHg, suggests critical ischaemia (pain at rest, ulcer, necrosis, see Lower Limb Ischaemia).
  • Autonomic neuropathy Diabetic Neuropathy increases arteriovenous shunting, which makes the foot feel warm to the hand and the veins full. However, in spite of seemingly good blood flow the oxygen supply of the tissues is decreased.
• Changes in the skin, changes in nails, ulcers, macerations, blisters and infections
  • Thickening of the skin in the pressure areas
  • Calluses (the risk of an ulcer is high if there are dark haemorrhages in the callus)
• Deformities (see also Figure 2 in http://iwgdfguidelines.org/wp-content/uploads/2019/05/IWGDF-Guidelines-2019.pdf)
  • Pes transversoplanus predisposes to a callus and ulcer in the middle of the ball of the foot.
  • Overlapping toes, hammer toes
  • Hallux valgus
  • Prominent metatarsal bone ends on the sole of the foot
  • Podoscopy or pedography will help in recognizing pressure sites.
• The shoes and their fit should be examined.
  • Are the currently worn shoes worn daily or only occasionally?
  • Is the shoe big enough (length of the foot + 1-1.5 cm)? Are there bulges around the first and fifth toes? Where does the lining appear worn?
  • Are the socks of a suitable size and made of soft cotton?

Foot ulcer Dressings for Healing Diabetic Foot Ulcers, Negative Pressure Wound Therapy for Treating Foot Wounds in People with Diabetes Mellitus, Pressure-Relieving Interventions for Treating Diabetic Foot Ulcers, Debridement of Diabetic Foot Ulcers

• Even minor injuries should be carefully treated and followed up.
• A neuropathic ulcer arises at the site of a callus or corn.
  • Prescribe rest, crutches and reducing the number of steps
  • Alleviation of the pressure load is the most important treatment.
    • An offloading insole, a removable cast walker, therapeutic shoe etc.
    • The ulcer will heal in approximately 1-1.5 months with a total-contact cast. Cast treatment should be carried out in a unit with appropriate experience. Cast treatment is contraindicated in the following cases: deep infection requiring drainage, severe ischaemia, broken skin on the foot or leg, severe oedema of the foot, often also poor cooperation, poor vision, problems with balance and significant obesity.
• Typical sites for an ischaemic ulcer are the tip of the toes, between the toes, at the lateral edge of the foot or on the heel. The surrounding skin is thin.
  • The possibility of vascular surgery must be assessed immediately in critical ischaemia.
  • An offloading insole, total-contact cast or special shoe may be needed.
  • Remember to treat risk factors, too; see Comprehensive Treatment and Follow-Up of Type 2 Diabetes Follow-Up of Type 1 Diabetes.
    • Thrombosis prophylaxis Lower Limb Ischaemia should be considered in patients with symptomatic lower extremity arterial disease without high risk of bleeding (rivaroxaban 2.5 mg twice daily and aspirin 100 mg once daily).
• Remember the possibility of osteomyelitis in deep ulcers.

Superficial fungal and bacterial infections

• The diagnosis and treatment of Fungal Infections should be based on fungal culture, the sample collected from cleansed skin after any bacterial infection has healed; see Dermatomycoses.
• Infectious (eczematoid) dermatitis (pictures 2 3) is often preceded by a fungal infection.
  • Pustular erythema of sudden onset between the toes and on the metatarsus
  • Antimicrobial drug therapy targeted at staphylococci should be started as early as possible (e.g. cephalexin 500 mg 3 times daily).
  • Potassium permanganate baths (1:10 000) and, in the pustular phase, a cream containing a corticosteroid and an antibacterial agent, covered by a compress moistened with physiological saline. The compress should be changed or moistened every 4-6 hours. As the infection subsides, the dressings should be made less occlusive and drier to accomplish a "dry wound".
• Paronychia in a patient with diabetes always requires serious attention. It is usually due to wrongly cut nails or tight shoes.
  • The patient should be instructed to cut the nails straight. A foot health practitioner/chiropodist/podiatrist can straighten the growth of the nail with a spring clip or some other device.
  • Antimicrobials (e.g. cephalexin 500 mg 3 times daily) may be indicated in the early phase.
  • Potassium permanganate baths. Neomycin and bacitracin should not be used because of the risk of allergy.
  • If paronychia becomes chronic, the edge of the nail should be cut and the nail root should be phenolized Paronychia and Ingrown Toenail. If the circulation in the foot is clearly impaired, the patient is referred to specialized care (the procedure cannot be performed under local anaesthesia).

Deep infections (osteomyelitis and cellulitis)

Charcot's neuroarthropathy

• This condition often involves rapidly progressing fragmentation of bones, joint injury, a predisposition to subluxation and luxation, and appears in a non-ischaemic foot of a patient with long-standing diabetes.
• The first symptoms are oedema, mild pain, heat and sometimes redness of the foot.
• Radiographic changes are visible in the late stage of the disease. A collapsed arch due to destruction of the TMT joints, resulting in a rocker-bottom foot, is typical. When needed, the diagnosis may be confirmed by MRI.
• CRP and erythrocyte sedimentation rate are normal; plasma alkaline phosphatase may be increased.
• The treatment is 3-9 months' immobilization with a cast and forearm crutches starting as early as possible. In the initial phase, a closed cast should be used.

Self-care and treatment of position deformities Patient Education for Preventing Diabetic Foot Ulceration, Prevention of Foot Ulcers in Diabetics

• Good foot hygiene and regular application of ointment, careful treatment of the nails, prevention of Fungal Infections
• Foot exercises and walking (but not barefoot in nature)
• Avoiding artificial warming and even minor injuries
• Prevention and regular removal of calluses and corns (Video Removing Clavus with Scalpel from Diabetic Foot Ulcer)
• Suitable shoes, ready-made or customised orthopaedic shoes when needed
• Offloading or biomechanical insoles
• Orthoses, toe splints, toe padding
• Surgical treatment: correction of hammer toes, bunion removal / straightening of toes, metatarsal resection
• Provide the patient with locally relevant patient information.