Neuropathic Ulcers

Fig. 13.1
Sausage-shaped right 4th toe with surrounding erythema; ulcer over the DIPJ probes to bone suggestive of osteomyelitis. Note the dry skin with toe deformity and callus buildup around the tip of the hallux and lateral border of the 5th toe – neuropathic ulceration from tight shoes


Fig. 13.2
Neuropathic foot. Note the dry skin (a, b), dystrophic nails (b), raised plantar arch (b), and distended foot veins (from autonomic shunting)


Fig. 13.3
Neuropathic ulceration in a patient with previous right hallux and 5th toe ray amputation. Like underlying infection. Not the hypertrophic callus rim around the ulcer due to inadequate offloading

Neuropathic ulcers are usually painless unless an arterial component or infection is present. The wound margins tend to display callus buildup, a useful clue to the underlying high pressure load. Pedal pulses are usually present unless there is a vascular component. Foot temperature is usually normal. Despite even a large plantar ulcer, the patient may walk normally, without a limp, highlighting their lack of sensation.

Other aspects of abnormal foot pressures and neuropathy including limited joint mobility (LJM), dry skin, and various deformities (pes cavus, flattened plantar arch, hallux rigidus, hammer toes, claw toes, etc.) should also be elicited [18, 19].

13.5 Multidisciplinary Foot Teams

In many Western centers, diabetic patients with foot ulcers are managed in specialist foot clinics run by a multidisciplinary foot team (MDFT). This may include a combination of diabetes physicians, specialist nurses, podiatrists, vascular surgeons, orthopedic surgeons, orthotists, or psychologists. Patients with new ulcerations, swelling, or discoloration should be referred to these services promptly from primary care for urgent assessment and management. In the presence of severe infection, they may require prompt hospitalization for intravenous antibiotics. Evidence supports the role of the MDFT with one study finding that the total number of amputations fell by 70 % over 11 years following improvements in foot care services and implementation of an MDFT. [20]. The National Institute for Healthcare and Care Excellence (NICE) recommends that hospitals should have a care pathway for patients with diabetic foot problems, which should be managed by an MDFT, consisting of healthcare professionals with specialist skills and competencies [21].

13.6 Identification and Treatment of Infection

Diagnosis of infection in diabetic foot ulcers can be difficult as signs one would expect to find locally (pain, erythema, swelling, and raised temperature) may not be present [8]. Systemic signs may only be present in severe infections such as osteomyelitis or septicemia. Infection in a diabetic foot wound can produce signs such as poor blood glucose control, increased slough/exudate, pus, foul smell or change in smell, pain, and warmth. Although diagnosing infection at an early stage can be challenging, it is crucial in preventing progression of the infection and thereby preventing necrosis, gangrene, and amputation [22]. More than half of all diabetic foot ulcers will become infected at sometime so a high index of suspicion is vital [23]. The following factors increase the likelihood of an infection developing [24]: a positive probe-to-bone test, ulcer present for more than 30 days, a history of recurrent DFUs, a traumatic foot wound, the presence of peripheral arterial disease in the affected limb, a previous lower-extremity amputation, loss of protective sensation, the presence of renal insufficiency, and a history of walking barefoot.

Signs of severe infections include widespread inflammation, crepitus, bullae, necrosis, or gangrene. If a wound appears infected, appropriate cultures should be sent (soft tissue, secretions, or bone if osteomyelitis is suspected). All open wounds will be colonized with pathogens so superficial swabs are unlikely to culture the specific pathogen responsible for the infection. Empirical antibiotics should be prescribed in accordance with local microbiology advice while awaiting culture results and sensitivities. Other useful investigations include a full blood count, C reactive protein, renal function and liver function. Evidence does not support antibiotic therapy for ulcers that do not appear infected. Topical antibiotics may be useful in cases where there is poor vascular supply leading to reduced antibiotic tissue penetration, but the evidence base supporting their use is thin.

Diabetic patients with signs of infected ulceration should have a radiograph of their foot to detect any evidence of osteomyelitis. Signs of osteomyelitis on a radiograph include focal destruction of cortical bone, periosteal new bone formation, soft tissue swelling secondary to inflammation around the area, and focal osteoporosis caused by hyperemia. Conventional radiographs may not display any signs of osteomyelitis for up to 10 days so other types of imaging such as MRI should be used, where available, if clinical suspicion remains despite a normal radiograph [25]. If MRI is contraindicated or unavailable, a labeled leukocyte imaging scan can be performed instead. Radiography can also be used to exclude a foreign body in tissues which is common with plantar neuropathic ulcers.

13.7 Identification of Deformities

As described previously, deformities of the feet can result from neuropathic changes, and these deformities create extra pressure points which are at high risk of ulceration. Feet should be inspected for common deformities including hammer toes (a fixed flexion deformity of the proximal interphalangeal joint), claw toes (flexion at the distal and proximal interphalangeal joints with dorsiflexion at the metatarsophalangeal joint), prominent metatarsal heads, and pes cavus (high arch).

13.8 Management of Neuropathic Ulcers

The basic aims of management are wound closure with prompt healing and prevention of the development of further ulcers.

These management goals can be achieved through a variety of measures including: local wound care (debridement), infection control, ensuring adequate blood supply, VAC therapy, adjunctive therapies, pressure offloading, treating underlying factors (intrinsic and extrinsic), patient education, temperature self-assessment, fat pad augmentation, and specialist shoes.

13.8.1 Debridement

This is the removal of devitalized, damaged, or infected tissue from an ulcer and hence exposure of healthy tissue. Exposure of the healthy tissue aids the healing process, and removal of devitalized tissue reduces the risk of infection. Debridement may be a single procedure, or it may need to be ongoing for maintenance of a clean wound bed [26].

Sharp debridement can be done in an outpatient setting by a podiatrist or foot specialist. A scalpel, scissors, or forceps are used to remove devitalized tissue. This procedure can be painful so adequate analgesia is essential. Assessment of the vascular supply to the feet is important before undertaking extensive sharp debridement. Patients requiring revascularization should not undergo sharp debridement due to the risk of trauma to tissues that are vascularly compromised.

Surgical debridement should be considered in cases of extensive necrotic tissue or localized fluctuance indicating pus or gas in the surrounding soft tissue. This involves excision or wider resection of both nonviable and healthy tissue from wound margins until a healthy bleeding wound bed is achieved.

Autolytic debridement is a process by which the body attempts to shed devitalized tissue with the use of moisture. If tissue is kept moist, it will degrade naturally and deslough from the underlying healthy tissues. The presence of matrix metalloproteinases (MMPs) enhances this process. These are enzymes produced by damaged tissue, acting to disrupt the proteins that bind the dead tissue to the body. Autolytic debridement uses the body’s own enzymes and moisture to rehydrate, soften, and liquify hard dead tissue and slough using semiocclusive or occlusive dressings (e.g., hydrogels, hydrocolloids) to maintain a moist environment and enhance the body’s natural debridement process. This technique can be used when there is a small amount of nonviable tissue, if other methods of debridement are unsuitable, or for maintenance debridement. It is a slow process which increases the risk of infection and maceration.

Maggot debridement therapy involves applying sterile larvae of the green bottle fly to a neuropathic ulcer. This technique can achieve rapid digestion of necrotic tissue and pathogens and therefore promote granulation. Larval therapy is not recommended to be used as the only method of debridement in neuropathic ulcers as calluses cannot be removed by the larvae [27]. It is also not recommended for use in ulcers with an ischemic component as the process can cause or aggravate severe pain.

Hydrosurgical debridement uses a high-energy saline beam as a cutting implement to remove devitalized tissue [28]. The benefits of this technique include a short treatment time and the ability to remove most, if not all, dead tissue from the wound bed. Disadvantages include the need for specialist and expensive equipment.

13.8.2 Infection Control

Steps that can be taken to prevent infection developing in an ulcer include debridement of devitalized tissue, tight diabetic control (hyperglycemia leads to an increased risk of infection and also impairs healing in an established wound infection), care with footwear (checking for objects inside socks and shoes), and not walking barefoot to avoid any pathogens entering any wounds.

13.8.3 Ensuring Adequate Blood Supply

As previously described, neuropathic ulcers are commonly complicated by a degree of ischemia. Poor blood supply to the foot will impair its healing capacity. If the blood supply is good and recurrent insults are avoided, the ulcer should heal well. However, there may also be a vascular component that requires attention from surgical colleagues. It is important to recognize vascular deficits and refer early to vascular surgeons.

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May 13, 2017 | Posted by in GENERAL SURGERY | Comments Off on Neuropathic Ulcers
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