Essential Principles In Treating Diabetic Forefoot Ulcers

Jason R. Hanft, DPM, FACFAS, Daniel Hall, DPM, and Mikkel Jarman, DPM

What The Literature Reveals About Offloading

The essential keys of offloading are to prevent repetitive stress and microtrauma, and reduce pressure to the ulceration site. Each patient will require a different offloading modality according to his or her physical activities.36 One can accomplish offloading through the use of crutches, walkers, wheelchairs, removable walking braces, rocker bottom soles, shoe cutouts, felt foam, patella tendon bearing braces or total contact casts (TCCs).37 The gold standard for offloading is TCC as this modality has proven to be extremely effective in reducing plantar pressure and successful in the promotion of healing foot ulcers.38 Researchers have shown that TCCs reduce pressure at the site of ulceration by 84 to 92 percent.39 Regardless of whether one uses a TCC or a controlled ankle motion (CAM) walker boot, offloading the wound site has proven to be beneficial in wound closure.28

   Maintaining wound closure can be a very difficult task. Ghanassia and colleagues found the primary healing rate of diabetic foot ulcers to be 77.5 percent, but noted a high rate of ulcer recurrence (60.9 percent) within 6.5 years and that 43.8 percent of these ulcers ultimately lead to amputations.40 Clinicians can mitigate ulcer recurrence with regular office follow-up and comprehensive foot examinations for early detection. The most important markers of long-term prognosis are the identification of peripheral neuropathy and levels of mechanical foot pressure.41 The use of therapeutic shoes and intense educational training, including the education of the family, contribute to lowering the incidence of ulceration and major amputation.42

   Clinicians often prescribe custom diabetic footwear to prevent ulceration, particularly for patients who have suffered prior ulceration and are at higher risk. The primary goal is to redistribute pressure on the plantar foot surface to relieve pressure at locations that are at risk. A deep toe box will help offload dorsal pressure to the interphalangeal joint and plantar tip pressure of contracted toes. Evaluating the therapeutic treatment in neuropathic patients can be difficult as there tends to be inadequate feedback due to the presence of neuropathy.43

   One effective way to offload the forefoot is by using a lightweight, semi-rigid rocker bottom type of shoe. A rocker bottom sole will allow offloading of the forefoot during gait and standing, redistributing the plantar force to the leg. It is also important to have a wide base to the shoe to allow for bulky dressings.44 Custom-molded healing sandals are another consideration for the offloading of forefoot ulcers. They do provide less pressure than a boot and may be a better alternative to a CAM walker but can be very difficult to walk in. Research has shown that offloading with felt alone decreases pressure at the ulceration site by 4 to 50 percent.45

   Reducing the duration of force and plantar pressure at the ulceration site is an important element in the ulcer prevention strategy. Once peripheral neuropathy is present, there is a reduced or absent protective sensation. This increases plantar loads and tissue stress.46 The goal is to decrease the entire plantar pressure and strain. The time duration of stress is important to determine the amount of stain. There is a linear relationship between shear stress and the rate of strain.47 Neuropathic diabetic patents can apply up to 2 to 2.5 times their body weight to a plantar ulcer during each step, exceeding the body’s skin elasticity by up to three times.48

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