Offloading

Pressure reduction, termed offloading, is necessary to heal diabetic foot ulcers. Common wound sites include the dorsal aspects of lesser digits, the apices of digits and the plantar metatarsophalangeal joints. Healing is often problematic on the plantar surfaces of feet on which ambulation occurs. Without the reduction of pressure, diabetic foot wounds are slow to heal. Wounds occur due to multiple factors including genetics, poor footwear, trauma, gait abnormalities and surgery (Botros et al., 2019). Affected feet often have structural limited ranges of motion in the ankle, subtalar and metatarsophalangeal joints leading to higher plantar pressures (Crisologo et al., 2019; Wrobel & Najafi, 2010). The goal of offloading is to reduce plantar pressures and shearing force while allowing a reasonable amount of ambulation (Crisologo et al., 2019).

Offloading is achieved through devices designed to redirect higher pressures away from wound sites and redistribute pressures more evenly across the foot. General guidelines for offloading plantar DFU are described in Table 2. There are published guidelines available to direct the selection of an offloading device such as the Offloading Plantar Pressures in Diabetes Product Picker that includes a comprehensive list of devices. Selection of the most appropriate device should be made in consultation with patient-centered concerns. Offloading should consider the following factors: location of the wound, presence of infection, presence of disease (neuropathy, PAD, inflammatory disorder), skin integrity of surrounding area, gait abnormalities, balance, activity level (e.g. how many hours of the day is the patient on their feet?), occupation (e.g. are there footwear constraints at work?), housing conditions (e.g. are there stairs in the home?), funding available and patient adherence to attend all follow up visits (Botros et al., 2019; Crisologo et al., 2019; Lu & McLaren, 2017).

Conservative Offloading of Neuropathic Plantar Forefoot and Midfoot ulcers

Location matters. The location of the wound is a starting point to guide the selection of the device as shown in Figure 1. First line offloading options for forefoot and midfoot neuropathic plantar wounds include knee high devices with an appropriate foot-device interface (Botros et al., 2019; Bus et al., 2020; (Lazzarini & Jarl, 2021). Knee high devices can be removable or irremovable. Common irremovable devices include total contact casts (TCC) and removable cast walkers made irremovable with bandaging (instant TCC). Specialized training is required to apply total contact casts to prevent iatrogenic events. Irremovable devices better offload than removable devices since they cannot be easily removed by the patient (Botros et al., 2019; Lazzarini & Jarl, 2021). However, despite best practice recommendations, TCCs are prescribed less often in practice due to the specialized training involved, time-intensive nature of application and patient factors (Fife et al., 2014; Wu et al., 2008).

Removable cast walkers require modifications of their insoles to be customized to the patient’s foot (foot-device interface) (Bus et al., 2020). Second line and third line offloading options for forefoot and midfoot neuropathic wounds include removable knee-high devices and ankle-high devices, respectively (Bus et al., 2020). Removable cast walkers are available in both ankle and knee heights. These options should be explored if the patient is unable to tolerate an irremovable device due to any of the offloading factors described earlier.

Fourth line options include orthopedic footwear and felted foam modifications (Bus et al., 2020). In the author’s experience, felted foam padding can be combined with other offloading modalities in appropriate cases to enhance offloading. The use of padding requires an understanding of each patient’s foot biomechanics to mitigate the edge effect.

Conservative Offloading of Neuropathic Plantar Heel ulcers

Plantar heel wounds are challenging to offload. Consider using a knee-high offloading device or alternative offloading device that is shown to reduce heel pressures (Bus et al., 2020). Lu and McLaren (2017) recommend total contact casts with modifications, healing sandals with insole modifications and non-weight bearing options to offload plantar heel wounds.

Table 2 Offloading Device Considerations According to the Location of a Plantar DFU