Epidemiology

Diabetes mellitus affects the microvascular and macrovascular system (23). It’s recognised as one of the leading causes of morbidity and mortality in the UK. It is estimated that worldwide, there are 285 million people with diabetes, and around 3 million of those live in the UK. This is anticipated to grow by a further 54% worldwide by 2030 (23). Diabetes care in the NHS has an approximate price tag of £9bn, with up to 20% (£600m) being used to treat diabetic foot problems (NICE, 2011). The main cause of non-traumatic lower limb amputations is diabetic foot ulceration and it is estimated that £252m is being spent annually on amputations. Recent figures suggest that each year in the UK, around 5,000 people with diabetes undergo leg, foot or toe amputations — equivalent to 100 occurring each week (NICE, 2011) (23).

 

Diabetic foot problems are the most common cause for admission, and patients admitted for in-patient care are often hospitalised for 4–6 weeks. One of the major risks to patients with diabetic foot disease is amputation, which could be minor (mid-foot to toe); or major, (mid-foot and above). Up to 85% of amputations are preceded by foot ulcers. 20–40% of people with diabetes are estimated to have neuropathy and about 5% have a foot ulcer. Recognising those people at risk of ulceration is therefore crucial (23).

 

Aetiology

The aetiology has many components. The major underlying causes are noted to be peripheral neuropathy (PN) and ischemia from peripheral arterial disease (PAD). Other factors are trauma, deformity, callus formation, and oedema (21). PN damages the nerves, leading to loss of the protective pain sensation, and occurs in 75% of diabetic patients. PAD usually occurs as a result of atherosclerosis. Foot ulceration due to PAD is less common, and accounts for approximately 5% of cases. Neuropathy can be related to lack of sensation (sensory neuropathy; The foot becomes insensate and can subsequently become deformed, leading to abnormal walking and tissue breakdown from abnormal pressures placed upon the foot) and may also cause atrophy and weakness of muscles in the foot (motor neuropathy). Additionally, there are effects on the autonomic nervous system which cause changes in blood flow and sweat secretion (autonomic neuropathy). 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Clinical Signs

They present as round, punched out lesions with a characteristic rim of callous; indicating increased plantar pressure and shear forces. Unless infected, there’s minimal drainage. Eschar or necrotic material is also uncommon unless accompanied by infection or significant vascular disease (24). A history of factors that place patients at increased risk of ulceration including foot deformity; ill-fitting footwear; mechanical injury, thermal injury and chemical trauma typically caused by an OTC preparation bought to remove hard skin. (17)

 

Symptoms of PAD: Most people with atherosclerotic disease of the lower extremities are asymptomatic and others develop ischemic symptoms. Some patients attribute ambulatory difficulties to old age and are unaware of the existence of a potentially correctible problem. Patients who are symptomatic may present with intermittent claudication (pain on walking) due to reduced blood flow to the lower limbs, ischemic pain at rest, or a non-healing foot ulcer. Intermittent claudication increases with ambulation until walking is no longer possible, and it is relieved by resting for several minutes. Signs of infection in these lesions are likely to be ‘masked’ as people with diabetes may not show typical inflammatory response to infection (pain, erythema, swelling and leucocytosis). Despite this inherent difficulty, diagnosis of infection is essentially clinical. Also, infection of the diabetic foot often involves superficial and deep tissues, including bone. This is unlike other common chronic wound types and will therefore manifest in different criteria for infection (17).

 

Treatment

Prevention is almost more important than the treatment. Key aspects in the choice of dressing are how it will perform in a shoe, whether it will withstand pressure and shear forces, how well it will absorb any fluid from the wound and how often the dressing needs to be changed (17). There is an array of treatments including local wound care (e.g. daily application of petroleum based moisturiser to the feet can minimise dry and cracked skin caused by autonomic neuropathy), total contact casting, therapeutic exercise (gait and mobility training) and temporary or permanent footwear.  Of course there are also medical interventions e.g. appropriate antibiotic therapy and glycaemic control.  There are also surgical interventions e.g. debridement of necrotic tissue, antimicrobial bead implants and amputation (24).