http://www.medicine-on-line.com Diabetic foot disease: 1/12 Diabetic Foot Problems Author: Affiliation: Rebecca Wong BN, MSc(Health Care) Prince of Wales Hospital, Hong Kong SAR Introduction Diabetes Mellitus (DM) is a chronic illness affecting millions of people all over the world. In 2003, the global prevalence of DM was estimated to be194 million. It is predicted to reach 333 millions by 2025. In Hong Kong, the percentage of people suffering from DM is growing. The 1995 population-based survey showed an aged-adjusted prevalence of 8.5% (5). It is estimated that there are 400,000 to 600,000 diabetic patients in Hong Kong (1). DM can lead to serious complications such as cardiovascular disease and the wellknown triopathies (retinopathy, nephropathy, and neuropathy). The complications of foot disease in DM are also well recognized. DM is a major cause of nontraumatic leg amputation (3). Foot ulceration, infection, and Charcot neuropathic osteoarthropathy are three serious foot complications of DM that can lead to gangrene and lower limb amputation. For the majority of DM patients, skin ulcer is the initial condition that eventually leads to amputation (7). The prevalence of foot ulceration in the general DM population is 4-10%. The life time risk for foot ulceration in these patients is about 15%. Data from several studies have shown that foot ulcer precedes approximately 85% of all amputation performed in patients with DM. Risk of ulceration and amputation increases 2-4 folds with both age and duration of DM. Foot ulceration and amputation affect the quality of life of diabetic patients negatively
http://www.medicine-on-line.com Diabetic foot disease: 2/12 and create an economic burden for both the patients and the health care system. Therefore, no effort should be spared in attempts to identify, prevent and manage potential diabetic foot disease. Risk Factors for Foot Ulceration The risk factors for foot ulceration are as follow: o Personal history of previous ulceration or amputation o Peripheral sensory neuropathy o Peripheral vascular disease o Traumatic injury from poor footwear, walking barefoot or objects inside the shoes o Foot deformities such as prominent metatarsal heads, claw toes, hammer toe deformity, Pes Cavus, nail deformities, and deformity related to previous trauma and surgery, etc. o Callus formation o Charcot neuropathic osteoarthropathy o Limited joint mobility o Long duration of diabetes o Poor diabetic control. Mechanism of Injury The mechanism of injury of diabetic foot disease can be understood through separating the contributing components into intrinsic and extrinsic factors. Major intrinsic factors include neuropathies, abnormal biomechanics, and peripheral vascular diseases. Out of peripheral sensory neuropathy, motor neuropathy and autonomic neuropathy, peripheral sensory neuropathy is the leading factor giving rise to diabetic ulcerations (9, 10). Approximately 45-60% of such ulcerations are purely sensory neuropathic, while up to 45% have other components. With diminished sensory feedback, patients with sensory neuropathy are more prone to foot injuries and the complications that follow. Motor neuropathy resulting in muscle wasting can lead to foot deformities such as foot drop, equinus, hammer toes, and
http://www.medicine-on-line.com Diabetic foot disease: 3/12 prominent plantar metatarsal heads. All these render the patients biomechanical disadvantages predisposing them to foot ulcerations. Autonomic neuropathy results in dry skin with cracking and fissuring, thus, creating a portal of entry for bacteria and cultivating an environment for future infected ulcers. Biomechanically, foot deformities resulting from limited joint mobility and neuroarthropathy contribute to elevated focal pressure. For example, the reduction in ankle, subtalar, and first metatarsophalangeal (MTP) joint mobility has been shown to result in high focal plantar pressure with increased risk of ulceration (12). Charcot neuroarthropathy is the culprit behind the most devastating acute and chronic deformities, including bony dislocation and collapse of the arch of the foot. Peripheral vascular disease rarely leads to foot ulcerations directly. However once an ulceration develops, arterial insufficiency predisposes the patients to prolonged healing and imparts an elevated risk for future amputation. Extrinsic components of diabetic foot disease include trauma and social factors. Trauma to the foot in the presence of peripheral sensory neuropathy is an important cause of ulcerations. These include puncture wounds, blunt injury, and injury of moderate repetitive stress resulting from walking or day to day activity. These often lead callus formation under the metatarsal heads. Shoe-related trauma has been identified as a frequent precursor to foot ulcerations. Among patients who have lost protective sensation, injuries from small foreign bodies in footwear and pressure from poorly fitting shoes can cause puncture wound to develop unnoticed. However the most common mechanism of injury is unperceived, excessive, and repetitive pressure on plantar bony prominences, such as the metatarsal heads. Social factors have also been shown to be associated with foot ulcerations. Important ones include low social status, poor assess to healthcare services, limited education, and a solitary life style. Last but not least, the underlying problem: Diabetic Mellitus, is an important factor to be considered in understand the mechanism of injury. Poor Diabetic control is an
http://www.medicine-on-line.com Diabetic foot disease: 4/12 important risk factor for amputation. The Diabetes Control and Complications Trial (DCCT) (6) found that chronically poor diabetic control is associated with a conglomeration of systemic complications. Therefore, tight glucose control can significantly reduce the risk of diabetic foot disease. Clinical Examination All patients with DM should be offered a thorough foot examination at lease once every year (2). Patients with diabetic foot related complaints will require detailed evaluations more frequently. Clinical examination of diabetic foot should include the followings: Vascular Examination Look for o Color changes: Cyanosis Dependent rubor Erythema o Integumentary changes consistent with ischemia: Skin atrophy Nail atrophy Abnormal wrinkling Loss of pedal hair Feel for o Pulses: dorsalis pedis posterior tibial popliteal femoral
http://www.medicine-on-line.com Diabetic foot disease: 5/12 Check for o Capillary refill (normal is < 3 seconds) o Presence of edema o Temperature difference Neurological Examination Dorsal Column: Vibration by 128 Hz tuning fork Proprioception Spinothalamic tract: Pain by pinprick Temperature by hot and cold objects Light touch (via both dorsal column and spinothalamic tract) by Semmes-Weinstein 10-gram monofilament. Reflexes: Deep tendon reflexes in knee and ankle Babinski s reflex Musculoskeletal Examination o Biomechanical abnormalities (deformities): Hammertoes Bunions Flat or high-arched feet Charcot deformities Limited joint mobility Tendo- Achilles contractures/ equines
http://www.medicine-on-line.com Diabetic foot disease: 6/12 o Gait o Muscle power: Passive and active Non-weight bearing and weight bearing Foot drop Intrinsic muscle atrophy o Plantar pressure: Computerized devices Harris ink mat Dermatological Examination o Skin: Color Dryness Texture Integrity Calluses Hair Fissures (especially over posterior heel) o Nail: Onychomycosis Dystrophic Atrophy Hypertrophy Paronychia o Ulceration, gangrene, infection o Interdigital lesions o Tinea Pedis o Markers of diabetes: Shin spots indicative of diabetic dermopathy Necrobiosis Lipoidica diabetic rum Granuloma annulare
http://www.medicine-on-line.com Diabetic foot disease: 7/12 Footwear Examination o Type of shoes o Fit o Shoewear and pattern of wear o Foreign bodies inside shoes o Insoles and orthoses According to American Diabetic Association position statement (14), evaluation of neurological status in the low-risk foot should include a quantitative somatosensory test, using the Semmes-Weinstein 5.07 (10 gram) monofilament. Initial screening for peripheral vascular disease should include a history for claudicating and an assessment of the pedal pulses. An ankle-brachial index (ABI) may be considered, as many patients with peripheral arterial disease are asymptomatic. Patients with significant or a positive ankle-brachial index (i.e. ABI < 0.9) should be referred for further vascular assessment. The skin should be assessed for integrity, especially between the toes and under the metatarsal heads. Minor skin conditions such as dryness and tinea pedis should be treated to prevent the development of more serious complications. Management of Diabetic Foot Ulcer The primary goal in the treatment of diabetic foot ulcer is to obtain wound closure as quickly as possible. The resolution of foot ulcer and decrease in the rate of recurrence can lower the probability of lower extremity amputation in the diabetic patients (10). The essential therapeutic objectives include: Debridment Pressure relief (off-loading) Management of wound
http://www.medicine-on-line.com Diabetic foot disease: 8/12 Management of infection Management of ischemia Surgical management Initially, a diabetic ulcer of the foot must be assessed for infection, debridment of devitalized tissue, and examined by radiography to detect foreign bodies, or bony deformities. Effective treatment requires that weight bearing be eliminated or reduced to a minimum. Debridment of necrotic tissue is essential in the treatment of chronic wound. Necrotic tissue removed on a regular basis can increase the rate of wound healing. Adequate debridment must always precede the application of topical wound healing agents, dressings, or wound closure procedures. Reducing pressure to the diabetic foot ulcer is an essential component of treatment (12). The choice of off-loading modality should be determined by the patient s ability to comply with the treatment, as well as the location and the severity of the ulcer. The following off-loading techniques have been used in the management of diabetic foot ulcers: Total non-weight-bearing: wheel chair and bed Total contact casting Removable walking braces with rocker bottom soles Sandals or wedge shoes Healing sandal - surgical shoes with molded plastazole insole Accommodative cushioning dressing: felt, foam, felted-foam, etc Shoes cutouts ( toe box, medial, lateral, or dorsal pressure points) Assistive devices: crutches, walker, cane, etc. For wound management, generally, a moist wound healing environment bandaged to protect the wound from trauma and local contamination is essential to facilitate the healing process (13). The type of dressing selected depends upon the size, depth, location and the wound surface. Topical healing agents or antiseptics may be used
http://www.medicine-on-line.com Diabetic foot disease: 9/12 to aid healing. Pedal ulceration provides a portal for pathogen entry and can therefore lead to secondary infections. All ulcers must be assessed for infection, because this process can threaten both limb and life. Infection must be identified as either local (soft tissue or osseous), or systemic. Treatment requires early incision and drainage with broad-spectrum antibiotics. Arterial perfusion is a vital component for diabetic ulcer healing and must be assessed in these patients. Revascularization with distal bypass grafting procedures allows normal healing of ulcers to occur and helps to salvage limbs. Education and Prevention Prevention is always better than cure. Prevention is an important element in avoiding ulceration and subsequent major amputation in DM patients. This can be best accomplished with a multidisciplinary approach consisting of a team of specialists and personnel providing a coordinated process of care. Team members should include: the primary physician, diabetologist, endocrinologist, vascular surgeon, orthropaedic surgeon, diabetic nurse educator, podiatrist, orthrotist and wound care nurse. Regularly scheduled podiatrist visit including debridment of callus and toenails provides an opportunity for foot examination and patient education. Identification of the high risk patients and tailoring a foot care prevention program for each of them is considered effective in reducing the incidence of ulceration and lower extremity amputation (4). Patients with diabetes can benefit from education on foot care and footwear. Patient with high risk foot conditions should be educated regarding their risk factors and the appropriate management (14). Patient with sensory neuropathy should understand the implications of the loss of protective sensation, the importance of foot monitoring on a daily basis, the proper care of the foot - including nail and skin care,
http://www.medicine-on-line.com Diabetic foot disease: 10/12 and the selection of appropriate footwear. They should be educated on the implication of sensory loss and the ways to substitute other sensory modalities (eg: hand palpation, visual inspection) for detection of early problems. Patients with visual difficulties, physical constraints preventing movement, or cognitive problems that impair their ability to assess the conditions of their feet will need other people, such as family members, to assist in their care. Patient with neuropathy or evidence of increased plantar pressure may be adequately managed with well-fitted walking shoes or runners. Patients with evidence of increased plantar pressure should use footwear with insole that cushions and redistributes the pressure evenly. People with bony deformities (eg. hammer toes, prominent metatarsal heads, bunions) may need extra depth or width shoes. Those with extreme bony deformities (eg. Charcot foot ) that cannot be accommodated with commercial therapeutic footwear may need custom-molded shoes. Conclusion The population of diabetes and its foot disorder are growing. Ulceration and amputation affect the quality of life of diabetic patients. The human and financial costs of lower extremity amputation are high. Therefore, the need for a good limb salvage program is imminent. Dabetic foot complications can be reduced through appropriate prevention, detection and management programs. Foot care programs emphasizing on preventive management can reduce the incidence of foot ulceration. The multidisciplinary team approach to diabetic foot disease has been demonstrated as the optimal method to achieve favorable rates of limb salvage. References 1. Chan, C. N. J., Ko, G. T. C., Chow, C. C., Yeung, V. T. F., So, W. Y., Li, J. K. Y.,
http://www.medicine-on-line.com Diabetic foot disease: 11/12 Ng, M. C. Y., Lee, S., Lee, Z. S. K, Critchley, J. A. H. C., & Cockram, C. S. (1999). Diabetes Mellitus in Hong Kong Chinese. Journal of the Asean Federation of Endocrine Societies, 17 (2 sup.) Jul., 1-6. 2. American Diabetes Position Statement: Preventive Foot Care in Diabetes (2000). Diabetic Care 23 ( Suppl. 1) S55-56. 3. Chan, J. C. N., Yeung, V. T. F., Chow, C. C., & Cockram, C. S. (1996). Treatment of diabetic complications and associated conditions. Hong Kong Practitioner, 18 (7), 379-387. 4. International Working Group on the Diabetic Foot. International Consensus on the Diabetic Foot, Amsterdam, The Netherlands, 1999. 5. Janus, E. D. (1997). Epidemiology of cardiovascular risk factors in Hong Kong. Clinical and Experimental Pharmacology and Physiology, 24, 987-988. 6. The Diabetes Control and Complications Trial Research Group (1993): The effect of intensive treatment of diabetes on the development and progression of long-term complications in IDDM. New England Journal Medicine, 329, 977-986. 7. Frykberg, R.G., Habershaw, G.M, Epidermiology of the diabetic foot: ulceration and amputations. In: Contemporary Endocrinology : Clinical Management of Diabetic Neuropathy, p.273, edited by A veves, Human press, Totowa, NJ, 1998. 8. Ramsey, S.D., Newton, K., Blough, D., McCulloch D.K, Incidence, outcomes, and cost of foot ulcers in patients with diabetes. Diabetes Care 22:382-387, 1999. 9. Reiber, G.E., Vileikyte, L., Boyko, E.J., Del Aguila, M., Smith, D.G., Lavery, L.A, Casual Pathways for incident lower-extremity ulcers in patients with diabetes
http://www.medicine-on-line.com Diabetic foot disease: 12/12 from two settings. Diabetes Care 22:157-162, 1999. 10. Frykberg, R.G. Diabetic foot ulcers : current concepts. J. Foot Ankle Surg. 37:440-446,1998. 11. Shaw, J.E., Boulton, A.J.M. The pathogenesis of diabetic foot problems. An overview. Diabetes 46(sppl.) :S58-S61,1997. 12. Mayfield, J.A., Reiber, G.E., Sanders, l.j., & Co. Preventive foot care in people with diabetes : technical review. Diabetes Care 21: 2161-2177, 1998. 13. Hogge, J., Krasner, D., Armstrong, D.G., & Co. The potential benefits of advanced therapeutic modalities in the treatment of diabetic foot wounds. J Am. Podiatr. Med. Assoc. 90:57-65,2000. 14. American Diabetes Position Statement: Preventive Foot Care in Diabetes (2004). Diabetic Care 27 ( Suppl. 1) S63-64.