One of the leading causes of ulceration in diabetic patients is an increased plantar foot pressure. Healing these ulcers needs prompt control of infection, adequate blood supply, excellent wound care, and offloading ( the technical term used to refer to the redistribution of pressure on the ulcerative area.) Of these factors, offloading is believed to be the most challenging in treating chronic wounds. With the evolution of diabetic foot care over the years, podiatrists have discovered and used various approaches to offload these wounds including complete bed rest, the use of felt pads, and total contact casting, to name a few.
The selection of the right offloading method to be used however largely depends on having complete awareness of the potential causes of the increased plantar pressure in the affected diabetic foot.
Weighing the Offloading Options and Goals
Offloading normally requires placing something on the foot such as some device or padding. Tthe first and most significant technique is actually debriding the hyperkeratotic skin that surrounds the wound edge, the first aspect of the offloading method that should be immediately addressed. The thick, rough, and calloused edges of the wound, when left untreated, will prevent the edges from moving toward the center and eventually cause increased plantar pressure.
Although many think that the biggest pressure would be in the center of the wound, plantar ulcers can have considerable depth. With the natural offloading of the wound cavity, plantar foot pressure intensifies at the edge of the wound. It is for this reason that plantar foot ulcers require very frequent debridement to serve the most ideal offloading results.
The same holds true when offloading a plantar lesion with an aperture pad or a simple cut-out pad. The standard padding for wound accommodation establishes an edge effect. In training, podiatrists have been instructed to place customized or prefabricated pads at the edge of the wound to facilitate healing. These pads however may actually bring more pressure on the skin surrounding the plantar foot lesion causing it to increase in size and in some cases remain unchanged.
The use of devices that encompass the whole foot with total contact pressure help podiatrists in offloading the plantar foot lesion, which balances the forces on the plantar foot—the primary goal of total contact pressure relief. Offloading the ulcerative area comes with the redistribution of the forces.
Another simple method in offloading the diabetic foot is gait modification. Lessening the walking speed or doing the shuffling type of gait can minimize the pressure on the forefoot. It is however sometimes difficult for patients to change their walking patterns drastically. Regular ambulation is recommended to minimize other cases of morbidity.
The objective of any offloading technique should be the appropriate redistribution of plantar pressure from one particular area to a larger area that encompasses the whole plantar foot. An efficient offloading modality always takes the destructive forces of shearing and vertical stress into consideration.
Examining the Use of Total Contact Casting
Clearly, total contact casts have been considered as the benchmark for offloading plantar neuropathic ulcers. The general idea behind the method, despite the many variations in its application, is a cast just below the knee that conforms to the anatomical contours of the patient with use of a little padding. The special fit of the cast material to the surface of the foot brings about an increase in the weight-bearing surface area, which assists in distributing plantar pressure from one or two different areas to the entire plantar foot.
Among the benefits that patients obtain from TCCs are limitation of edema, reduction of pressure at the ulcer site, protection from trauma, and the immobilization of the edges of the wound; but doctors believe that the patient’s inability to remove the device is the best feature of the method.
Despite the low rate of complications of TCC cases, this offloading method is not without contraindications. It should not be used on patients with gangrene, severe peripheral arterial disease, deep abscess, chronic venous stasis ulcers, or osteomyelitis.
Evaluating the Benefits of Removable Cast Walkers
The increasing popularity of the use of removable cast walkers in the treatment of neuropathic ulcers can be owed to the device’s easy application, the daily wound care that it permits, and its potential use even for patients with infected ulcers. However, some practitioners find it a significant deterrent as a non-compliant patient can have it easily removed. This drawback has led to the concept of “instant TCC,” a removable cast walker with some layers of fiberglass, bandage, or plaster that prevents the easy removal of the device.
RCWs are believed to minimize forefoot plantar pressure as it helps keep the ankle at 90° and consequently limits propulsion. Four available RCW brands were compared and evaluated based on their ability to minimize dynamic foot pressure. Of these four, the Active Off-Loading Walker showed the lowest peak pressure. Pneumatic Walker came second, third was the Three D Dura-Stepper, and the highest pressure came from the CAM Walker. Also, no significant peak pressure was reported between the TCC and the Active Off-Loading Walker.
Similar to the Active Off-Loading Walker, the DH Shoe should also be considered. The shoe is frequently recommended for use as an intermediary solution between other shoe modalities and a walking cast. The DH Shoe offers excellent pressure relief while at the same time allowing a continuous weight-bearing effect.
Assessing the Advantages of Half Shoes
Half shoes have long been used to reduce pressure after a forefoot surgery. They come designed with a wedged sole whose end is proximal to the metatarsal heads’ level. By theory, half shoes are designed to distribute ground-reactive forces on the forefoot by getting rid of propulsive gait. For this, wound care specialists advice their patients with plantar forefoot lesions to use these special half shoes.
Half shoes have been found to encourage an increased amount of daily activity on patients as opposed to those under the TCC treatment. Utmost care must be practiced however to assess patients for instability or lower extremity weakness when advising the use of this method.
Compared to TCCs and RCWs however, half shoes come last in minimizing plantar pressure. The same holds true for comparing half shoes with TCCs and RCWs in terms of healing wounds within 12 weeks.
Looking into the Perks of Insoles and Prescription Orthotic Devices
There is a wide availability of materials that can be used as accommodative insoles with diabetic patients. Coming in a multi-layer design, insoles are based on a positive model of the foot of the patient. Initially, when placing plastazote in the shoe, it is critical that the insert be re-examined in every subsequent visit as they easily and quickly become flat and ineffective over time.
For obese diabetic patients, the use of a half-inch plastazote or equivalent materials is recommended. It must be ensured however that the need for extra-depth shoes be examined as the thickness can pose a problem when wearing normal depth toe-boxes. In prescribing thick inserts, the foot must be carefully examined for any area of increased pressure or rubbing.
With many factors to be considered, relieving pressure can prove to be a daunting task. For tougher cases, establishing a good working relationship with your foot specialist is essential. Gross peripheral edema, large bony prominences, wound location, previous amputation, and similar other cases all play critical parts in picking the right and most appropriate offloading option that will work for you.
Conclusion
Evidence-based research and study show that the total contact casting modality is the most ideal to use for offloading the plantar foot, while at the same time keeping the patient ambulatory. This however cannot generally be applied to pressure relief footwear once the patient’s wounds are healed. More and more research is being conducted to evaluate the appropriate thickness of material that will be required to adequately dissipate pressure based on the patient’s body mass.
With patient non-compliance considered, more efforts must be exhausted to offer patients with preventive care. It is never good enough to purchase a diabetic shoe and insert to provide offloading relief for the insensate foot, regular examination of the insoles and shoes must be diligently done during at-risk foot care visits.
The selection of the right offloading method to be used however largely depends on having complete awareness of the potential causes of the increased plantar pressure in the affected diabetic foot.