Offloading A Diabetic Foot Ulcer In The Developing World

At one point, limb loss due to diabetes occurred every 30 seconds. Recent research has reduced the figure to every 20 seconds.^1-3 Eighty-five percent of lower limb amputations follow incidence of a diabetic foot ulcer and most are preventable.^4,5

Neuropathic diabetic foot ulcers (DFUs) are the primary factor leading to lower extremity amputations in most cases.⁶ Up to 25 percent of those with diabetes will develop a foot ulcer.6 After a major amputation, 50 percent of patients will have their other limb amputated within two years.⁷ The relative five-year mortality rate after limb amputation is at least 50 percent. Compare this to the five-year mortality rates of lung cancer (86 percent), colorectal cancer (39 percent), breast cancer (23 percent), Hodgkin disease (18 percent) and prostate cancer (8 percent).⁸ People with a history of a DFU have a 40 percent greater 10-year mortality rate than people with diabetes alone.⁹

When one is standing, each foot bears 50 percent of body weight. During walking, there are times when one foot bears 150 percent of body weight, which further increases with associated deformity or obesity. Two key forces act on the foot during walking. There is a vertical component perpendicular to the skin surface (vertical pressure/plantar pressure) and a horizontal component parallel to the skin surface (shear stress).¹⁰ Peak plantar pressure is reportedly less important a factor than peak shear pressure when it comes to the development of DFUs. In one study, peak plantar pressure preceded ulcers in only 38 percent of patients.¹¹

Small muscle atrophy with corresponding muscle weakness and deformity is present in the diabetic foot before the detection of clinical peripheral neuropathy. This muscle atrophy may lead to increased plantar pressure, even in the “low-risk” sensate diabetic foot.¹² Contrary to a common belief, these forces (both plantar and shear pressure) are highest at the edges of the wound and not at the center.¹³ The thick and callused edges of a wound have a tendency to roll inward and inhibit epithelial growth toward the center, contributing to non-healing of the ulcer.¹⁴

Repeated shear stress is known to cause calluses, which result in DFUs.¹⁵ Callus formation precedes ulcer formation in 82 percent of patients with DFUs.¹⁶ Calluses can increase the plantar pressure by as much as 30 percent.¹⁷ Motor impairment, shortening of the Achilles tendon (due to glycosylation) and possible rupture of the plantar fascia have the potential to produce equinus deformity and subsequently increase the pressure under the forefoot area.^18-22

In one randomized study involving 64 patients with DFUs, one group wore a total contact cast (TCC) alone while the other group had a percutaneous Achilles tendon lengthening in combination with TCC use.²³ In the first seven months of follow-up, 59 percent of patients in the cast-only group had re-ulceration versus 15 percent of those who also had the surgery. Achilles lengthening can reduce plantar pressures by approximately 28 percent.²³

Patients with diabetes are prone to a non-enzymatic glycation of their soft tissues, which can in turn lead to tightening of the periarticular structures around the joints.²⁴ This limited joint mobility is experienced to some degree for more than five years by greater than 66 percent of patients with diabetes.²⁵ In one study, researchers noted DFUs were present in 65 percent of those with peripheral neuropathy and limited joint mobility in comparison to only 5 percent in those with peripheral neuropathy without limited joint mobility.²⁵

Since callused edges have a tendency to roll inward and make center wound healing poorer, debriding the hyperkeratotic and callused skin surrounding the wound edge is the first step of offloading. Facilitating a short, shuffling gait offers yet another simple means of offloading the foot, especially for the forefoot.^26-28 Slowing the speed (from 1.19 meters per second to 0.83 meters per second) reportedly reduces peak plantar pressure by 18 percent at the heel, 11 percent at big toes and 11 percent at the medial part of the forefoot.²⁹

Emphasizing The Pivotal Role Of Offloading
When it comes to preventing DFUs, the most important factor is the education of patients, their relatives and family physicians. When preventive measures fail and a DFU develops, appropriate treatment should start early. Healing of these ulcers requires proper dressing of the ulcer(s), observing universal principles of hygiene, restoration of adequate vascularity, control of infection, good metabolic control of glycemia and lipids, cessation of smoking, and weight reduction. In the treatment of diabetic foot ulcers, offloading is most successful when it mitigates pressure at an area of high vertical or shear stress.³⁰

Offloading is defined as any measure to eliminate abnormal pressure points to promote healing or prevent recurrence of DFUs.³¹ Total non-weightbearing is impractical and difficult to achieve. Accordingly, the aim is to redistribute plantar pressures evenly, thus avoiding areas of high pressure that will prevent or delay healing. Boulton has repeatedly stated that it is not what you put on a DFU that heals it but rather what you take off the wound.³² Many methods of offloading are currently available but the TCC is known to be the gold standard of offloading.³³ Researchers have shown that TCCs reduce pressure at the site of ulceration by 84 to 92 percent.³⁴

Total contact casts reduce plantar pressure by increasing the weightbearing surface area. The TCC has several advantages such as forced adherence to offloading, protecting the foot from infection and reduction of edema.

In regard to the disadvantages of TCC, it is very costly since it has to be changed every week or so, and even more frequently if there is associated edema. Total contact casting also needs specially trained technicians and the procedure is time-consuming, both during application and removal. In addition, the cast can prevent local wound care and periodic monitoring of the wound. The TCC also poses difficulty with sleeping, bathing and driving, and can also affect gait stability.³⁵ The TCC may cause complications such as iatrogenic ulcerations, muscle wasting, osteopenia and leg length disparity. Use of the TCC is contraindicated in ischemic and infected wounds. Due to these disadvantages, TCC is currently in use by less than 2 percent of wound care centers in the United States.³⁶  

Removable cast walkers (RCWs) offer many advantages. They are much cheaper than TCCs. In comparing the treatment of non-infected neuropathic foot ulcers with TCCs, RCWs and half-shoes, Armstrong and colleagues showed an 89.5 percent healing rate for TCCs, a 65 percent healing rate for RCWs and a 58.3 percent healing rate for half-shoes at 12 weeks.³⁷

Removable cast walkers also need no trained technicians to apply or remove them, and take little time to apply or remove. With RCWs, local wound care and monitoring are possible. Physicians can use them for infected as well as ischemic wounds. Removable cast walkers also make it easier for patients to enjoy life activities such as sleeping, bathing and driving.

Non-adherence remains the greatest disadvantage of RCW. A study by Armstrong and colleagues showed that patients wear their offloading device (RCW) for less than 30 percent of their total daily activity.³⁵ An instant TCC (iTCC) renders RCWs irremovable and offers forced adherence. With this method, one wraps a few layers of plaster cast or fiber cast bandages after applying the RCW. The iTCC has comparable efficacy (80 percent for the iTCC versus 74 percent for the TCC at 12 weeks).³⁸ Aside from the TCC and RCW, there is a variety of therapeutic footwear with variable healing rates.

Why Offloading Is Challenging In Developing Countries
However, either due to economic constraints or because they are not available, these offloading methods are not commonly in use in the developing world.³⁹ Patients in the developing world need an offloading device that is economical, simple to apply and remove, and usable for all types of wounds.

The plight of offloading is very poor in the developing world due to poor infrastructure and awareness among physicians, patients and relatives. Doctors commonly ask patients to stay in bed for some time and they do not adhere as a rule. The sufferer might be the only breadwinner in the family. There is almost no arrangement for any training of physicians in podiatry and the little care that is available in bigger cities and towns comes from orthopedists and surgeons. Total contact casting is not affordable for most patients and there is a dire scarcity of trained technicians. Some diabetologists have raised improvised podiatric units in their clinic and look after the podiatric patients themselves, but are hard pressed as far as time is concerned.

What You Should Know About The Samadhan System Of Offloading
The team of physicians at LK Diabetes Centre in Lucknow, India has researched and developed an altogether new offloading device, called the “Samadhan System of Offloading,” which is very affordable, costing barely $1 in U.S. currency and has both removable (SS-R) and irremovable versions (SS-IR). Patients can use the Samadhan System with all forms of DFUs, namely infected, neuropathic, vascular and mixed DFUs. The word “Samadhan” is a Hindi word meaning solution.

The Samadhan System has the following components: a “Samadhan Unit” (a foam cylinder), a “retainer” (a piece of elastocrepe bandage) and “fasteners” (metallic hooks provided with the elastocrepe bandage or safety pins).

It is very simple to manufacture and we recommend that healthcare providers have a Samadhan manufacturing unit in their own clinic. One only needs a small space to accommodate a small table with a shelf to keep raw material and prepared Samadhan units. Items required for manufacturing a Samadhan Unit include a sheet of rubberized foam with a thickness of 1 cm and a density of 40 kg/m3, a saw blade, liquid adhesive, sealing wax and a pair of scissors.

Cut a piece of foam measuring 6 x 4 inches from the big sheet. Apply liquid adhesive on one side of the foam piece with a metallic applicator since the adhesive is corrosive. We apply with a saw blade. Then we carefully roll up the foam piece into a cylinder, saving the skin of fingertips, and put some weight on this cylinder to allow the adhesive to dry. One can use any weight, such a brick.

After about two hours, remove the weight and the Samadhan unit is ready for use. We recommend keeping several Samadhan units ready beforehand. One can cut the cylinder to the size of the plantar surface of the patient with the saw blade. After rendering proper wound care, including the dressing, the clinician can decide where to place the Samadhan Unit for adequate offloading. For example, if there is a DFU under the big toe, place a Samadhan Unit along the metatarsal heads and wrap the retainer. Then apply fasteners at the edge of the retainer.

The position of the Samadhan unit shall change as per the location of the DFU. If a DFU is present over the plantar surface of the heel, apply the Samadhan unit before the ulcer. In the case of a midfoot ulcer, one might use two Samadhan units, one before and the other after the ulcer. Both the Samadhan unit and retainer are washable with soap and water. We provide two sets to every patient so they can change these items as they become dirty. Indeed, they often become soaked in discharge from the infected ulcers. The frequency of dressing changes depends upon the mobility and weight of the patient. Mostly, they need no change for 10-15 days. We ask patients while walking to use commonly used sandals with Velcro and felt to be fastened over the dorsal surface of the foot.

A Closer Look At Early Results With The Samadhan System
In our case report in the Journal of Diabetic Foot Complications, a patient with multiple plantar ulcers, including one large ulcer on the midfoot, achieved total healing after eight weeks using two Samadhan units.⁴⁰      

In one of the oral abstracts presented at the American Diabetes Association meeting in 2005, the removable Samadhan System had much better healing rates of Wagner grade 1 diabetic foot wounds in comparison to common footwear (73.3 percent versus 13.3 percent) with much less healing time (42 days versus 60 days).⁴¹ To render the Samadhan System irremovable, one can apply sealing wax to the edges of the retainer.⁴²

There are several potential mechanical benefits.
1. The Samadhan System reduces both peak plantar pressure and peak sheer pressure.
2. The Samadhan System provides a rocker effect.
3. The device reduces the pressure/time integral at the forefoot and rearfoot by reducing the contact time of the forefoot as well as the hindfoot during the gait cycle.

The Samadhan System is very safe although we have noticed some minor side effects.
1. Minor erosion of fingertips while rolling the foam cylinder. With a little caution, one can prevent this.
2. There may be shifting of the Samadhan unit from the site of placement since feet are often insensate. When shifting does occur, the device mostly shifts forward or backward, and sometimes over the ulcer itself, but some offloading still occurs. No harm occurs since the unit is quite soft in consistency. Educating patients to check the units from time to time can minimize this.

In Conclusion
The Samadhan System is a simple, affordable and effective offloading measure which, we hope, is capable of making a sea change in diabetic foot care in the developing world. It imparts a clear message: Improvisation is the key to success.

Dr. Lakshmi K. Shankhdhar established North India’s only diabetes clinic, the LK Diabetes Centre in Lucknow, of which he is the Medical Director and endocrinologist. He is the fourth Indian to receive the Wockhardt-Harvard Medical Excellence Award and Visiting Fellowship of Harvard Medical International, the international arm of Harvard Medical School. He has presented several abstracts and lectures at many international conferences on diabetes in addition to chairing some international conferences. He is the Principal of the Lekhraj Diabetes Hospital and Medical College.

Dr. Kshitij Shankhdhar is a diabetologist. He established the first diabetic foot clinic of North India with the Lucknow Diabetic Foot Care Clinic and Research Centre in Lucknow, India. Dr. Shankhdar has lectured at a variety of international conferences including the American Diabetes Association annual conference, the Diabetic Foot Global Conference (DFCon) and the Malvern International Diabetic Foot Conference.

Dr. Uma Shankhdhar is medical nutrition therapist at LK Diabetes Centre in Lucknow, India.

Dr. Smita Shankhdhar is a diabetes educator at LK Diabetes Centre in Lucknow, India.

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For further reading, see “Pertinent Insights On Offloading For Ulcerations” in the May 2014 issue of Podiatry Today, “Overcoming Barriers To Adopting The Total Contact Cast In Your Practice” in the August 2015 issue or the DPM Blog, “How Closely Can We Monitor Offloading For Patients?,” by David G. Armstrong, DPM, PhD, MD at https://tinyurl.com/o4ddg2m .