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Pedorthic Management of the Neuropathic Foot

Ernesto Castro, CPed

Consequently, it has been forced upon me that gangrene is not Heaven-sent but is earth-born.
–Elliott P. Joslin, MD

The Menace of Diabetic Gangrene, New England Journal of Medicine , 1934;211:16–20

As Lee J. Sanders, DPM, has noted, "Elliott P. Joslin recognized that lower-limb amputation was not an inevitable complication of diabetes but the result of modifiable risk factors. He believed that a team approach to diabetes care, including patient education and podiatric care, could prevent or minimize limb loss" (p 17).¹ The certified pedorthist is an important member of the clinic team treating people with diabetic neuropathy and similar disorders. Provision of proper footwear and appropriate custom foot orthoses are important elements in the comprehensive management of this challenging pathology.

Diabetes can be considered a public health problem of epidemic proportion in the United States. The number of US citizens with diabetes has been estimated at 15.7 million in 2000, with 798,000 new cases diagnosed every year.² Patients with long-term, inadequately controlled blood sugar levels are at significant risk for serious complications that affect the lower limbs, including peripheral vascular disease, nephropathy, peripheral neuropathy, and osteoarthropathy.

Once the foot becomes insensate and can no longer feel pain, the risk for ulceration increases substantially. Neuropathic ulcers usually are found in high-pressure areas of the foot, such as the metatarsal heads and the base of the fifth metatarsal. Neuropathy also is associated with intrinsic muscle atrophy, and the resulting biomechanical abnormalities that lead to contracture of tendons and deformities, such as claw, hammer, or mallet toes, may cause plantar and distal pressures on the digits. These high-pressure areas are also prone to ulceration in this population. Ill-fitting shoes with inadequate room in the toe box may create excessive pressures on the dorsum of these deformed toes as well.

Foot ulcers, if not treated effectively, can lead to infection, osteomyelitis, and ultimately lower limb amputations. The morbidity and mortality of diabetes-related amputations have been well documented and estimated to account for millions of dollars in health care costs each year. Therefore, the potential savings from healing neuropathic ulcers quickly and keeping them healed long term are substantial.

It is well accepted clinically that optimal footwear, which includes extra-depth shoes, custom foot orthoses, and biomechanically appropriate shoe modifications, is an essential element in the treatment of foot ulcers and in the prevention of reulceration of the high-risk diabetic foot. Researchers have consistently shown that rocker soles can significantly reduce forefoot pressures.³ There is also evidence that rocker sole modifications more effectively reduce forefoot pressures than does unmodified extra-depth footwear.⁴ Chantelau and colleagues have reported that geriatric feet tend to be wider than commercially available footwear,⁵ and that specially designed "diabetic" shoes are effective in reducing the rate of reulceration in high-risk patients with neuropathy.⁶ Based on these findings and similar results from other researchers, the value of optimal pedorthic management is increasingly being recognized as an important facet in comprehensive management of the neuropathic foot.

THE HUHUKAM EXPERIENCE

Wesley Yamada, DPM, is chief of podiatry at HuHuKam Memorial Hospital, in Sacaton, Arizona, located on the Gila River Reservation, where the Pima and Tohono O'Odham Native American tribes have the highest incidence of type 2 diabetes per capita in the world. In 1990, Dr. Yamada initiated a comprehensive program for this population, with pedorthic management as an integral part of the protocol. Before initiation of this program, an average of 24 diabetic-related major lower limb amputations were performed each year among the diabetic population of these tribes. This is one of the highest documented amputation rates per capita in the world.

A review of major lower limb amputations before 1990 revealed that poorly fitting footwear or the absence of shoes was at least partially responsible for most ulcerations and the resulting amputations. An aggressive campaign to screen and classify patients' feet started in 1990, and high-risk patients were scheduled for pedorthic consultation.

Pedorthic modalities commonly provided include:

1. In-depth shoes

2. Protective inserts

3. Custom-molded foot orthoses

4. Biomechanically appropriate shoe modifications

   1. Rocker soles

   2. Medial or lateral stabilizers (buttress)

   3. Sole spread to widen specific plantar areas of the shoe as needed

   4. Dorsum vamp balloon patches

5. Custom-molded shoes with custom foot orthoses

There is a consensus in the clinical literature that factors such as sensory dysfunction, limited joint mobility, foot deformities, partial foot amputation, and the presence of ulceration can be used to guide the prescription of pedorthic management for patients with neuropathy.⁷ Lower Extremity Amputation Prevention (LEAP) risk factor categories are the basis for footwear prescription in our clinic.⁸ The LEAP program was developed at the Gillis W. Long Hansen's Disease Center and adopted by the Bureau of Primary Health Care of the Health Resources and Services Administration, a branch of the US government.⁹ The purpose of this program is to dramatically reduce the incidence of lower extremity amputations in individuals with diabetes mellitus, Hansen's disease, or any other disorder that results in the loss of protective sensation of the feet.

There are four risk categories, beginning with Category 0 as the lowest risk group:

Category 0

Risk

1. Has disease that leads to insensitivity

2. Has protective sensation

3. Has not had plantar ulcers

Management

1. Education and counseling

2. Proper fitting shoes

3. Proper shoe style

Category 1

Risk

1. Does not have protective sensation

2. Has not had a plantar ulcer

3. Does not have foot deformity

Management

1. In-depth shoes/proper fit

2. Protective accommodative inserts

Category 2

Risk

1. Does not have protective sensation

2. Has not had a plantar ulcer

3. Does have a foot deformity

Management

1. In-depth shoes/proper fit

2. Custom foot orthoses

3. Rocker soles

4. Possible custom shoes

Category 3

Risk

1. Does not have protective sensation

2. Has a history of planter ulcer (deformity, amputation)

Management

1. In-depth shoes/proper fit

2. Custom foot orthoses

3. Rocker soles

4. Custom healing sandal

5. Extended steel shank (or rigid carbon fiber)

6. Possible custom shoes

Because so many of the patients seen in our clinics are at such high risk, we hypothesized that eliminating even a single extrinsic causative risk factor would be an effective treatment step in reducing major lower extremity amputations. Our preliminary results generally support this assumption. Since 1980, we have reduced the amputation rate in our patient population by more than 80%, resulting in an estimated savings to the health care system of $10 million.

We currently are screening more than 800 patients per month, with an average of 83% having a diagnosis of diabetes mellitus and 34% presenting with ulcerations. In 2003, the total number of major amputations was four, and none was attributed to improper footwear or a lack of footwear. We believe that these preliminary pilot data support the experience of most experts who treat diabetic foot disorders, which is that a comprehensive program of foot care for patients with diabetes decreases patient morbidity and resource consumption.

REVIEW OF THE SCIENTIFIC EVIDENCE

It should be noted that although the value of pedorthic management of high-risk feet is fairly well accepted in the clinical literature, few controlled randomized studies have been conducted on this topic. This limitation in available scientific evidence means that specific orthotic and pedorthic decisions are primarily clinical decisions made on an individual basis for each patient. Littleman et al.¹⁰ looked at the role of footwear in preventing foot lesions and found that many variables cited as protective measures did not prospectively predict the outcome. Their data identified six predictors that were significant at a 0.2 level:

1. Whether special shoes were recommended.

2. Whether footwear had an appropriate width for the patient's foot.

3. Whether footwear had an appropriate length for the patient's foot.

4. Whether footwear worn outside the house was more protective (e.g., Oxford style).

5. Whether footwear worn inside the home was more protective (e.g., Oxford style).

6. Whether footwear worn inside the home was made from leather versus cloth.

Maciejewski et al.¹¹ recently completed a structured literature review on the effectiveness of therapeutic footwear in preventing reulceration that identified only nine studies that investigated this topic. They noted a number of limitations in the design of available studies but concluded that risk ratios from the scientific literature suggest that protective footwear does have some effect in reducing reulcerations. One major problem identified is that using noncompliant patients as the control group may overstate the effectiveness of the intervention being examined.

These researchers noted that the protective benefit of therapeutic footwear increases in patients with severe deformities or pre-existing partial foot amputations. Interestingly, the most rigorous experimental study reviewed did not demonstrate a statistically significant difference between patients wearing their own shoes and those with the footwear being studied.¹² It has been suggested that this may have been attributable, at least in part, to approximately 40% of this study's participants having protective sensation.¹³

Some researchers have suggested that the patient education component of the diabetic foot clinic and regular examination by a health care specialist may be more important than is generally appreciated. This is a fertile area for additional investigation. In a recent commentary,¹⁴ Douglas Smith, MD, noted, "The evidence suggests that a shift in the diabetic foot care paradigm may be in order" and that the clinical emphasis should be on ensuring that all persons with diabetes and foot risk conditions have adequate footwear and regular access to health care providers.

The conclusion of Maciejewski et al.¹¹ summarizes current clinical thinking as well as the available scientific evidence: "Providers and patients should jointly explore individualized strategies to decrease the events that give rise to foot ulcers" (p 1774).

Correspondence to: Ernesto Castro, CPed, 1306 East Main Street, Mesa, AZ 85203; e-mail: .

ERNESTO CASTRO, CPed, is president of Custom Footwear, Inc., Mesa, Arizona.

References:

1. American Diabetes Association. Message from the president, health care and education. Improving foot care for people with diabetes: barriers to amputation prevention. Professional Section Quarterly, Fall 2000.
2. White J. Therapeutic footwear for patients with diabetes. J Am Podiatr Med Assoc 1994;84:470–479.
3. Brown DB, Wertsch JJ, Harris GF, et al. Effect of rocker sole on plantar pressures. Arch Phys Med Rehabil 2004;85:81–86.
4. Pratt SFE, Louwerens J-WK. The influence of shoe design on plantar pressures in neuropathic feet. Diabetes Care 2003;26: 441–445.
5. Chantelau E, Gede A. Foot dimensions of elderly persons with and without diabetes mellitus: a data basis for shoe design. Gerontology 2002;48:241–244.
6. Busck K, Chantelau E. Effectiveness of a new brand of stock 'diabetic' shoes to protect against diabetic foot ulcer relapse: a prospective cohort study. Diabet Med 2003;20:665–669.
7. Dahmen R, Haspels D, Koomen B, Hoeksma AF. Therapeutic footwear for the neuropathic foot. Diabetes Care 2001;24: 705–709.
8. www.medschool.lsuhsc.edu/dfp/Categories.PDF.
9. bphc.hrsa.gov/leap/WhatIsLEAP.htm. National Hansen's Disease Programs (NHDP), 1770 Physicians Park Drive, Baton Rouge, Louisiana 70816.
10. Littleman DF, Marriott DJ, Vinicor F. The role of footwear in the prevention of foot lesions in patients with NIDDM: conventional wisdom or evidence-based practice? Diabetes Care 1997;20(2): 156–162.
11. Maciejewski ML, Reiber GE, Smith DG, et al. Effectiveness of diabetic therapeutic footwear in preventing reulceration. Diabetes Care 2004;27:1774–1782.
12. Reiber GE, Smith DG, Wallace C, et al. Effect of therapeutic footwear on foot reulcerations in patients with diabetes: a randomized controlled trial. JAMA 2002;287:2552–2558.
13. Cavenaugh PR, Boulton AJM, Sheehan P, et al. Letter to the editor. JAMA 2002;286:1231.
14. Newswise.com. Widespread prescribing of diabetic footwear questioned. May 2002. diabetes.about.com/library/blnews/blnJAMAfootwear502.htm.