Poor or neglected feet often lead patients down the path of ulceration, infection and amputation.1 People with diabetes are at higher risk for these sequelae. Up to 25 percent of the diabetic population will have at least one foot ulceration during their lifetime with 85 percent of lower-limb amputations being preceded by an ulcer.2,3
The latest Centers for Disease Control and Prevention (CDC) National Diabetes Statistics Report (2014) reported 29.1 million people (9.3 percent) in the United States have diabetes.4 The cost of treatment of diabetes and its complications in the United States in 2007 was approximately $116 million with 33 percent of that amount going toward ulcer treatment.3 This number is likely to increase as the diabetic population continues to grow with current estimates suggesting that diabetes will affect 366 million people worldwide by 2030.1
The purpose of this article is to remind us, as podiatric physicians, of the often underappreciated and perhaps sometimes forgotten importance of routine diabetic foot care. Although nail pathology may not be the most glamorous aspect of podiatry, it is our “bread and butter” and we need to be experts in providing this service to our patients.
How Nail Changes Can Lead To Ulcers
There are several pathways to ulceration in patients with diabetic neuropathy, ranging from biomechanical issues causing calluses to stepping on a foreign body. One pathway toward ulceration that we may overlook is the dystrophic, mycotic and neglected toenail. Dystrophy in the toenail can be a manifestation of hereditary, congenital or acquired conditions.
In the patient with diabetes, the origins of ulcers lie in microtrauma or changes in the vascular and nutritional supply to the toenail. Onychomycosis results from dermatophytes (most notably Trichophyton rubrum and Trichophyton mentagrophytes), yeasts (Candida albicans) and non-dermatophyte molds.5,6 It is this thickened nail that causes injury to adjacent skin (whether on the same toe or neighboring toe, known as a “kissing ulcer”) and can erode the nail bed and hyponychium, progressing to nail bed ulceration, paronychia, cellulitis of the skin or osteomyelitis to the underlying bone.7,8 The nail bed is a very thin tissue layer between two and five cells thick with the distal phalanx located directly beneath, putting it at increased risk of bone infection.9
Researchers have shown that one in three patients with diabetes has onychomycosis, making them 2.77 times more likely to develop onychomycosis versus people without diabetes.5,8 Authors have identified tinea pedis infection as another starting point and predictor of foot ulceration in the diabetic population.10 Onychomycosis can precipitate tinea pedis and vice versa.10-12 Regardless of the starting mechanism, both fungal infections may lead to foot ulceration, cellulitis, osteomyelitis, gangrene and lower extremity amputation.13,14 Physicians can easily manage and treat onychomycosis and tinea pedis with scheduled podiatric assessment and intervention.
Predisposition to secondary (bacterial) infections may be a consequence of simply having diabetes. This is due to the multiple levels of compromise these patients have, whether it is diabetic peripheral and autonomic neuropathy, peripheral vascular and microvascular disease, immunosuppression, diabetic retinopathy, poor blood glucose control and/or a history of amputation.1,10,15 Even increased age, obesity and limited mobility can increase the potential for infection and are also obstacles to appropriate self care.5,15 Neuropathy prevents patients from feeling any trauma from the nail itself or shoe trauma that may be occurring in this local environment.
Additionally, approximately 20 to 30 percent of patients with peripheral arterial disease (PAD) have diabetes.16 The combination of the neuropathy, no feeling of any lesion development due to dystrophic, mycotic elongated toenails along with the vascular compromise will delay or prevent this lesion from healing. Ulcers stay open and exposed for a longer than ideal time, leaving them susceptible to colonization and infection.
Emphasizing The Role Of Toenail Debridement In Amputation Prevention
Sometimes as busy practicing podiatric surgeons, we forget that toenail debridement in the high-risk patient population is crucial in amputation prevention. Often our resident physicians do not even realize the importance until the patient comes in through the emergency department. At our institution, we provide routine care as an inpatient service often directed by the emergency room physician, primary care physician or infectious disease team. We find it important to stress to our residents, who are surgically driven, to remember the basics of what we do as well.
In a 1995 study, Reiber and colleagues showed that 7.5 percent of diabetic hospital admissions were caused by paronychia.12 The increased rates of onychomycosis in these patients may lend one to think the fungal infection to the nail had some effect. Improvement in foot care starting with debridement of toenail dystrophy and onychomycosis can reduce ulceration, cellulitis and infection rates. This can ultimately decrease complications arising from delayed diagnosis and their associated healthcare expenditures.2,15
Initially, it is important to evaluate these patients in the inpatient setting when possible or appropriate. Explain to patients their situation and stress to them the importance of personal at-home care as well as podiatric physician follow-up care after discharge. By having a podiatrist care for the nails, if a problem were to arise, treatments can start immediately to prevent for example, a neuropathic patient with PAD who cut himself from obtaining a chronic wound and infection. Morbach and colleagues, in an investigational study of 247 patients with an ulcer, found that 12 percent of those ulcers were attributed to “insufficient nail and foot care performed either by the patient, his family, or a professional.”17
In the Seattle Diabetic Foot Study, researchers compared the prediction of diabetic foot ulcer occurrence against certain risk factors and other clinical information in their study population.18 The presence of both tinea pedis and onychomycosis was statistically significant as a clinical finding relating to a higher risk of foot ulcers. Despite some of these fungal infections being treatable, diabetes and other comorbidities make this situation more limb-threatening. Interdigital maceration accounts for as many as 60 percent of cases of leg cellulitis while the fungal foot (toenails, interdigital or plantar) carries a significant risk for cellulitis (odds ratio 2.4) and is often a predictor for developing lower limb cellulitis.10,19
A study by Doyle and coworkers showed patients with diabetes and onychomycosis had a higher rate of foot ulceration, gangrene or a combination of the two.11 In their patient database study, researchers attributed 18 percent of gangrene and 10 percent of foot ulcers in patients with diabetes to starting with onychomycosis.
Recognizing The Value Of Preventative Care
In the end, preventative care is the key. Multiple studies have stressed the importance of patient and physician evaluation of onychomycosis with appropriate intervention.1,5,15 This intervention consists of educating patients as well as providing podiatric care. This also includes patients developing a relationship with their foot doctor for an education on how imperative it is to get in to see podiatrists if a problem should arise. Medicare allows for these patients to come to the office for routine evaluation and foot care every nine weeks. In the year 2000, almost 25 percent of the $1 billion in total Medicare payments to podiatrists was for nail debridement.21
Part of this evaluation is identifying the presence of tinea pedis and providing toenail care, often in the presence of dystrophy or onychomycosis. A Thomson Reuters Study from 2011 states that for every $1 of podiatric physician preventative care and treatment, between $9 to $13 and $27 to $51 in savings occur with Medicare and commercial insurance patients respectively.22 This preventative care is not only limb saving but has huge monetary saving implications for the healthcare system.
The treatment of onychomycosis is often difficult for patients with diabetes. Many products are available from topical agents and oral pills to lasers with varying degrees of success. Often this patient population does not have the patience, time, money or proper health status to participate in these treatments. Additionally, some of these oral medications have untoward side effects as well as drug interactions to other common medications they may be taking for more concerning medical conditions.5 Due to this, it is of the utmost importance to provide continued local/palliative care to these patients. Although a cure may be unrealistic in these immunosuppressed patients, maintenance is necessary to prevent avoidable problems.
Ultimately, physicians can do more. Care for toenails is an important role we play in the team approach to diabetes and the limb salvage team. By providing our part, along with having a close relationship with our patients as well as other members of the medical care team, we can prevent ulcers, save limbs and cut rising healthcare costs.1
We should not put this problem on the back burner. There are various methods from palliative care to potential cure in our armamentarium. In comparison to some of the other risk factors identified for cellulitis such as diabetes, PAD and lymphedema, controlling onychomycosis and the fungal foot is much more manageable through treatment.19 There are studies demonstrating that diabetic foot care programs started in the 1990s that emphasized preventative foot care and patient education have led to behavioral changes for the better in this population.1 Studies have shown topical and systemic antifungal treatments work, even in the diabetic population.5,7,13,19 In the more complicated patient, scheduled periodic nail assessment and intervention, such as debridement, are key.
There is an important clinical justification for treating fungal foot infections. This includes creating a foot care program for our patients consisting of education and performing periodic care with the hope of managing, if not preventing, these fungal foot infections. If not, the problem has the potential to worsen with the possibility of cellulitis, ulceration, gangrene, osteomyelitis and amputation. We can and should be doing more to decrease this modifiable risk.
We cannot prevent every complication in the diabetic foot but we can prevent something like an amputation resulting from a dystrophic fungal toenail. So remember to go back to the basics and stress the importance of routine foot care to each and every patient with diabetes.
Dr. Hood is a third-year Chief Resident with the Department of Foot and Ankle Surgery at Crozer Keystone Health System in Upland, Pa.
Dr. Cornell is fellowship trained in Diabetic Limb Salvage and is currently in private practice in Havertown, Pa. She is an attending physician with the Crozer Keystone Health System Residency Training Program. Please address any correspondence on this article to email@example.com .
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3. Carls GS, Gibson TB, Driver VR, et al. The economic value of specialized lower-extremity medical care by podiatry physicians in the treatment of diabetic foot ulcers. J Am Podiatr Med Assoc. 2011; 101(2):93-115.
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21. Rehnquist J. Medicare payment for nail debridement services. Department of Health and Human Services, 2002. Available at https://oig.hhs.gov/oei/reports/oei-04-99-00460.pdf . Published June 2002. Accessed Nov. 10, 2014.
22. Carls GS, Gibson TB, Driver VR, et al. The economic value of specialized lower-extremity medical care by podiatric physicians in the treatment of diabetic foot ulcers. J Am Podiatr Med Assoc. 2011; 101(2):93-115.
23. Gupta KA, Ryder J. Ten pearls for treating difficult nails. Podiatry Today. 2002; 15(9):28-36.
24. Blume P, Wilkinson JT, Key JJ. Treating difficult nails in diabetic patients. Podiatry Today. 2006; 19(3):91-98.
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Editor’s note: For further reading, see the November 2013 supplement “Onychomycosis And The Role Of Topical Antifungals, “Keys To Managing Severe Onychomycosis” in the May 2013 issue, “How To Address Onychomycosis In Patients With Diabetes” in the March 2012 issue and “Roundtable Insights On Treating Onychomycosis” in the May 2011 issue.
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