Management of Stage 3 Ulcerated foot
Diabetic Foot Ulcers are complex, chronic wounds, which have a major long-term impact on the morbidity, mortality and quality of patients’ lives. Individuals who develop a DFU are at greater risk of premature death, myocardial infarction and fatal stroke than those without a history of DFU. Unlike other chronic wounds, the development and progression of a DFU is often complicated by wide-ranging diabetic changes, such as neuropathy and vascular disease. These, along with the altered neutrophil function, diminished tissue perfusion and defective protein synthesis that frequently accompany diabetes, present practitioners with specific and unique management challenges.
A DFU is a pivotal event in the life of a person with diabetes and a marker of serious disease and comorbidities. Without early and optimal intervention, the wound can rapidly deteriorate, leading to amputation of the affected limb.
Mortality following amputation increases with level of amputation and ranges from 50–68% at five years, which is comparable or worse than for most malignancies. It has been suggested that up to 85% of amputations can be avoided when an effective care plan is adopted.
Successful diagnosis and treatment of patients with DFUs involves a holistic approach that includes:
- Optimal diabetes control
- Effective local wound care
- Infection control
- Pressure relieving strategies
- Restoring pulsatile blood flow
OPTIMISING LOCAL WOUND CARE
The European Wound Management Association (EWMA) states that the emphasis in wound care for DFUs should be on radical and repeated debridement, frequent inspection and bacterial control and careful moisture balance to prevent maceration. Its position document on wound bed preparation suggests the following TIME framework for managing DFUs:
Inflammation and infection control
Moisture balance (optimal dressing selection)
Epithelial edge advancement.
There are many methods of debridement used in the management of DFUs including surgical/sharp, larval, autolytic and, more recently, hydrosurgery and ultrasonic.
Vascular status must always be determined prior to sharp debridement. Patients needing revascularisation should not undergo extensive sharp debridement because of the risk of trauma to vascularly compromised tissues.
Inflammation and infection control
The high morbidity and mortality associated with infection in DFUs means that early and aggressive treatment — in the presence of even subtle signs of infection — is more appropriate than for wounds of other aetiologies (with the exception of immunocompromised patients
General principles of bacterial management
- At initial presentation of infection it is important to assess its severity, take appropriate cultures and consider need for surgical procedures
- Optimal specimens for culture should be taken after initial cleansing and debridement of necrotic material
- Patients with severe infection require empiric broad-spectrum antibiotic therapy, pending culture results. Those with mild (and many with moderate) infection can be treated with a more focused and narrow-spectrum antibiotic
- Patients with diabetes have immunological disturbances; therefore even bacteria regarded as skin commensals can cause severe tissue damage and should be regarded as pathogens when isolated from correctly obtained tissue specimens
- Gram-negative bacteria, especially when isolated from an ulcer swab, are often colonising organisms that do not require targeted therapy unless the person is at risk for infection with those organisms
- Blood cultures should be sent if fever and systemic toxicity are present
- Even with appropriate treatment, the wound should be inspected regularly for early signs of infection or spreading infection
- Timely surgical intervention is crucial for deep abscesses, necrotic tissue and for some bone infections.
Skin breakdown occurs with increased plantar pressure and more specifically, peak plantar pressure. Repeated loading of high peak plantar pressure during walking has been associated with skin breakdown although there is no definite threshold that predicts ulceration. One must also consider the duration and repetition of pressures. The rate of spatial change in plantar pressure distribution and the peak pressure gradient may be other markers of skin trauma.
Contact pressure on the plantar surface of the foot generates local internal forces that cause the subsurface tissue to deform. Breakdown occurs when the foot contacts the ground force, giving rise to distortion of the tissue and the formation of localized tissue damage. The maximum shear stress is vital in the mechanical failure criteria and may predict the tissue injury and skin breakdown.
Increased plantar pressure levels occur in patients with structural abnormalities such as Charcot’s neuropathy, clawtoes, hammertoes or other foot deformities. These irregularities can cause disruptions in the shape of the foot. Motor neuropathy is frequently associated with diabetic neuropathy. This in turn can lead to elevated foot pressures and ulceration. The combination of a deformed foot, loss of sensation, motor neuropathy and inadequate offloading may lead to tissue damage, ulceration, infection, amputations and death. Even in a patient with adequate perfusion, once an ulcer forms, studies indicate that healing is still delayed unless one catches the ulcer early and offloads it. Once an ulcer has healed, the rate of recurrence is 40 percent over four months.
Many patients with diabetic foot ulcers are obese. Patients suffering with diabetic foot ulcers place 2 to 2.5 times their body weight on the wound, thereby increasing pressure and strain with each step.7 The easiest way to decrease strain rate is to decelerate the speed at which the foot hits the ground as well as shortening the time the foot is in contact with the ground. Nonetheless, most patients with diabetic foot ulcers suffer from neuropathy and are unable to decelerate as they step on the ground. Therefore, they tend to step more forcefully in comparison to those without neuropathy. Effective offloading modalities address both force and strain rate.
In patients with peripheral neuropathy, it is important to offload at-risk areas of the foot in order to redistribute pressures evenly.
Inadequate offloading leads to tissue damage and ulceration. The gold standard is the total contact cast (TCC). This is a well moulded, minimally padded foot and lower leg cast that distributes pressures evenly over the entire plantar surface of the foot. It ensures compliance because it is not easy for the patient to remove. Using a TCC in patients with a unilateral uncomplicated plantar ulcer can reduce healing time by around six weeks.
Disadvantages of TCCs include:
- Must be applied by fully trained and experienced practitioners
- May cause skin irritation and further ulcers if applied inappropriately
- Prevents daily inspection (signs of spreading infection may go unnoticed)
- May disturb sleep
- Makes bathing difficult
- Patient may not tolerate it (especially in warm climates)
- May prevent patient’s ability to work
- Relatively high cost/low availability.
TCCs are contraindicated in patients with ischaemia because of the risk of inducing further DFUs. They are also not appropriate for patients with infected DFUs or osteomyelitis because, unlike removable devices, they do not allow wound inspection.
Removable devices may also be more pragmatic choices for less motivated patients because they allow patients to bathe and sleep more comfortably. However, using removable devices is complicated by patients not wearing the device as prescribed. This may account for their lower efficacy.
Charcot restraint orthotic walker. The CROW boot is a device composed of polypropylene material lined with Plastazote. It incorporates a total contact custom orthotic and utilizes a rocker-bottom sole. The CROW is the treatment of choice for many during the second and third stages of Charcot neuroarthropathy to maintain joint stability and alignment. One main advantage is that the clinician can remove the boot, treat the ulcer and reapply the boot during office visits. One can control edema with the boot, which allows the patient to ambulate.
Integrated prosthetic and orthotic system (IPOS). The IPOS model is designed for forefoot ulcerations. This “half shoe” has 10 degrees of dorsiflexion and a heel that is elevated 4 cm so the forefoot does not contact the ground. Patients who wear the IPOS often have difficulty with balance. Due to the dorsiflexion of the device, many patients with diabetes are unable to wear the shoe.
The OrthoWedge shoe (Darco) is very similar to the IPOS model with the exception of the sole extending to the toes. It helps in balancing and offers an off loading similar to TCC and improved healing rates.
Similarly Darco Heel wedge offers effective offloading of heel ulcers.
For ulcers at other locations customized offloading can be done with Darco Wound care shoe
There are various offloading modalities that have insoles with removable diamond or hexagonal shaped pieces to selectively offload particular areas of the foot.18 Patients with digital amputations or partial ray amputations can use custom toe filler insoles in conjunction with custom shoes. However, toe fillers are not indicated in the devascular patient because they increase the risk of tissue breakdown.
Single or multiple ray amputations or resections may result in a significant reduction of the weightbearing plantar surface. Custom-made multi-layer, multi-density insoles can help distribute pressure under the remainder of the foot. Patients with central ray resections usually need minor modifications to their molded insoles in order to ensure proper fit.
Compared to a regular sneaker, extra-depth shoes have an extra vertical depth of 3/16 to 1/2 inch. Patients with mild deformities, such as hammertoes or bunions, are often unable to wear regular shoes due to their toes feeling crowded. When it comes to diabetic patients with pedal deformities, regular shoes are not good options. In this patient population, regular shoes may lead to the development of recurrent ulcerations due to a likelihood of neuropathy and a resulting inability to detect pressure points.
A regular shoe is also not a good option for the neuropathic patient with or without deformity because these patients require a custom molded insole. “Diabetic” shoes like Darco Gentle step have enough extra depth to allow a custom insole for extra protection whereas regular shoes have trouble accommodating the custom insole. Custom insoles distribute pressure across the entire plantar foot, thereby decreasing shearing forces for the neuropathic patient. Different styles of insoles can be custom made from a mold of the patient’s foot in order to accommodate various deformities, including but not limited to hammertoe contractures, bunions and plantar foot ulcers.
Offloading is a very important aspect of wound healing that may often be undervalued. Diabetic foot ulcers are caused by a combination of pressure and strain. Effective offloading requires reduction of both of these forces. Currently, there is no perfect device. However, we do have the tools at our disposal that can yield very high healing rates. By recognizing the shortcomings of the offloading devices and tailoring the device to the specific needs of the patient along with proper patient education, we can drastically improve clinical outcomes.