An Overview of the Management of Diabetic Foot Ulcers
Davern R1, Hatunic M1, 2
1Department of Endocrinology, Mater Misericordiae University Hospital, Dublin, Ireland
2Medical School, University College Dublin, Dublin, Ireland
Lower extremity ulceration is the most common complication encountered clinically and has predicted 1-2% prevalence amongst US adults1 and an annual incidence of 2.2% in the UK2. The lifetime incidence of foot ulceration in persons with diabetes has been estimated at 15-25%3. This increase in foot ulceration is associated with increasing rates of infection4 and amputation5. The 5-year mortality in patients with diabetes and critical limb ischaemia is 30% and about 50% of patients with diabetic foot infections who have foot amputations die within five years which, put in perspective, is worse than some forms of cancer6. In Ireland, there were 1,297 hospital discharges for people with diabetes for foot ulceration without amputations in 2008 and 337 discharges for people with diabetes who had a lower limb amputation. This amounted to 23,601 bed days per year used for diabetics with lower limb ulcers and 11,622 bed days per year used for diabetics with lower limb amputations7.
The pathological processes that lead to diabetic foot ulceration are multifactorial, with arterial insufficiency and neuropathy both playing a major role. These two defects combined promote foot injury and subsequent ulcer formation. Diabetic ulcers are broadly divided into neuropathic ulcers and neuroischaemic ulcers. On examination, the neuropathic foot will be warm with palpable pulses but sweating is diminished. Ulcers tend to occur on the plantar aspect of the foot and toes. In contrast, the neuroischaemic foot will be cold with poor pulses and hairless. Neuroischaemic ulcers are often seen on the margins of the foot, especially on the medial surface of the first metatarsophalangeal joint and over the lateral aspect of the fifth metatarsophalangeal joint. Neuropathy in the lower limb can lead to the development of Charcot foot. Charcot joint refers to the accelerated degenerative changes and ultimate joint destruction that follows repetitive trauma to insensitive, neuropathic joints. Although diabetes is not the only cause of a Charcot foot it is by far the most common.
Healthcare physicians should use any consultation with diabetic patients as an opportunity for examination of their lower extremities. The International Working Group on the Diabetic Foot (IWGDF) recommends annual foot examination for diabetics with no peripheral neuropathy, 6 monthly for those with peripheral neuropathy, 3-6 monthly for those with neuropathy, peripheral arterial disease and/or foot deformity and 1-3 monthly in those with previous amputation8. An examination with monofilament and vibration fork is recommended to assess the level of sensation present in the patient’s lower limbs. Then an assessment must be done to determine if there is any concurrent infection9. This is of major clinical importance as one in five patients with an infected foot ulcer will undergo amputation10. This assessment should involve examining for warmth, tenderness, erythema, swelling and purulent discharge. If the ulcer is deep and overlies bone, osteomyelitis should be considered and initial investigations with plain radiography and MRI, which is more sensitive11.
Successful management of lower extremity complications in diabetics requires an extensive MDT input. Firstly, lifestyle factors need to be addressed to prevent recurrent ulceration. It should be emphasised to patients that meticulous footcare is the cornerstone of treatment. Other lifestyle adjustments include smoking cessation and the use of well-fitted footwear. It has been shown that patient education given over one to two sessions does not prevent ulcer recurrence at the 6 to 12 month mark12. Ill-fitting footwear has been identified as a risk factor for ulcer formation13. Hence why properly fitted footwear – neither too tight nor too loose, with the inside of the shoe being one to two centimetres longer than the foot, is important to prevent ulcer formation and ulcer recurrence. Unfortunately, adherence to lifestyle modifications, especially therapeutic footwear, can be poor. Many RCTs have shown that those patients who follow recommendations have much better outcomes than those who do not14,15. Wound dressings are used to protect the ulcerated area from further injury. There are many types of dressings available and, in general, dry wounds are treated with moisture promoting dressings whereas exudative wounds are managed with absorptive dressings.
Following on from lifestyle changes, surgical debridement is helpful in removing dead tissue and reducing the bacterial burden16. A systematic review of 45 randomised controlled trials showed no evidence to support prophylactic systemic antibiotics for lower limb ulcers17. If there is clinical suspicion of infection swabs should be sent and systemic antibiotic cover for gram positive and gram negative bacteria along with anaerobes should be used. Potential combinations would include penicillin and a beta lactamase inhibitor or fluoroquinolone or linezolid alone.
Several newer surgical procedures have been evaluated. Digital flexor tenotomy has been shown to be effective in several retrospective case series. This data showed that in 58 patients with impending ulcer formation, no ulcer was found at the 11-31 month follow up18,19,20,21. For the prevention of recurrent ulcer formation, Achilles tendon lengthening, joint arthroplasty, single or pan metatarsal head resection, or osteotomy have all been evaluated. Achilles tendon lengthening has been shown in one randomised control trial22 and several non-controlled studies23,24,25,26 to be effective in preventing ulcer recurrence in both the long and short term. There are fewer studies looking at joint arthroplasty but they have shown lower ulcer recurrence rates27,28,29. One retrospective cohort study showed a non-significant reduction in ulcer recurrence30. It must be taken into account that all surgical procedures carry risks and complications.
Recent publication in NEJM31 showed unfortunately that after the resolution of a foot ulcer, recurrence is common. The incidence rates for ulcer recurrence was estimate that roughly 40% of patients have a recurrence within one year after ulcer healing, almost 60% within three years, and 65% within 5 years. The authors in this paper31 summarised that once healed, foot ulcers frequently recur. This fact, coupled with demographic trends, requires a collective refocusing on prevention and a reallocation of resources from simply healing active ulcers to maximizing ulcer-free days for all patients with a history of diabetic foot ulceration.
In conclusion, lower extremity ulcers are significant problems for diabetic patients. Once healed, ulcers tend to recur. Aggressive early intervention is required to reduce the significant morbidity, mortality and hospital admissions associated with diabetic foot ulcers.
Dr Mensud Hatunic, Consultant Endocrinologist Department of Endocrinology, Mater Misericordiae University Hospital, Dublin, Ireland
Email: [email protected]
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