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The diabetic foot Torna agli editoriali

Anna Giulia Cattaneo, M.D.

Pressure ulcers are a known and previously debated cause of major invalidity in aging people. Those localized at the foot pose additional problems if the old person suffers from type II diabetes mellitus: in the western world this condition remains the main cause of amputation of the leg. The diabetic condition supports a complex pathogenesis for ulcer development with low probability of healing. From minor lesions up to the Charcot deformities, the diabetic foot represents a complex of lesions involving all the structures of lower extremities, from skin to bones.

Summarizing the main component supporting lesions at the lower extremities in diabetics, one must consider the defect of autonomic nervous system regulation, which acts in synergy with the poor vascularisation due to both the micro- and macro-angiopathy, aggravating it by impaired venous drainage. The peripheral nervous system alteration is principally responsible for altered sensitivity to temperature and possibly to other painful stimuli, with higher exposure to traumas and delay in recognizing and reporting minimal lesions.

Another condition complicating the outcome of diabetic ulcers in the foot is the presence of infections. Wound infections are often associated with poor diabetic control, and are supported by a polymicrobial flora of fastidious or resistant organisms: Pseudomonas aeruginosa, Staphylococcus aureus and fungi, frequently Candida albicans.

Ulcers of foot in older diabetic subjects are associated with high mortality rates. Principal conditions enhancing the risk of death are the spread of infections through blood, the general physical decline following the forced immobilization, the sequelae of major amputations. The high mortality rate associated to serious lesions in the foot in diabetic and older patients seems to be associated in several cases to concomitant cardiac failure, even at sub clinical level: aggressive treatment of this underlying condition can significantly improve survival even in subjects requiring major amputation.

Preventive measures to avoid lower extremities ulcerations are typically multidisciplinary, involving optimization of metabolic control, good hygiene of the foot, here including the use of appropriate socks to maintain the feet warm and wet, and of well designed shoes to avoid undue pressures or unbalanced gait and rehabilitative counselling. Attention should be paid to potential traumas deriving from banal events, like prolonged contact with warm surfaces or water, not recognized by the patient suffering from neuropathy. However, educational measures added to traditional care did not seem to be able to improve prevention in this class of individuals (Diabetologia. 2008, 51:1954-61).

Once the ulcer has developed, all efforts should be done to avoid amputations. The conservative treatment of ulcers is time requiring and expensive, and the outcome uncertain. Different epidemiological studies evaluated that primary healing occurred in no more than 60 to 70 % of patients, the inequality of samples explaining the diversity of results. A cohort study recently conducted in Sweden (Diabetologia. 2009, 52:398) evaluated factors impairing the tendency of serious wounds heal without amputation: the most important factors seemed to be the extent of neuro-vascular ischemia, the anamnesis positive for previous amputations, and the presence of multiple or very large lesions. Complicated diabetes and other co-morbidity, greater toe pressure and local infection represented additional pejorative prognostic signs. Aging was responsible for additional risk.

The importance of prevention of major amputation in aged, diabetic subjects is intuitively important, and it should represent a primary target in geriatric care. In recent years a decrease of major amputations has been observed, as a consequence of amelioration of therapeutic means for diabetic control as well as for local lesions. New treatments and technologies have been experienced, in addition to better compliance and control of the diabetes itself. A number of innovative treatments have been experienced: hyperbaric oxygen therapy, treatment with new formulations and growth factors, newest type of dressing or support for the foot, newer materials with bacteriostatic and bactericidal properties or enhanced ability for stimulate the skin repair (Diabetes Care 2007, 30: 586-90; J Control Rel 2007, 121:190-9; J Nanosci Nanotechnol. 2007, 7: 3888-91).

Attention has been paid to the availability of simplest predictive methods to score the risk of developing diabetic foot lesions and give a precocious and attainable prediction of risk for ulcer development and healing. A similar score has been proposed by a Scottish group (Diabetes Care, 2007, 30: 2064-9). More recently, a simplest score has been proposed at the Department of General and Transplant Surgery, University of Tübingen, (Germany). The evaluation of the prognostic output was attained on the basis of clinical parameters easily recorded by nurses or generic care givers, and namely the palpable pedal pulses, the wound area, the ulcer duration, and the presence of multiple ulcerations. The score was given by the sum of simplified sub-scores, 1 or 0, given respectively to the presence or the absence of palpable pedal pulses, wound areas at least 4 cm wide, lesions lasting at least 130 days and multiple lesions. The theoretical maximum score is 4. Not only the score in itself seemed to be correlated with the propensity to healing, but even its progression can be a diagnostic predictive value: an increase of 1 was indicative of 37% reduction in healing chance.

In conclusion, type II diabetes mellitus and its complications should never be considered as an unavoidable burden or fatality of the older age, but as a hazardous association charged by additional risks, that of ischemic wounds at lower extremities between others. The presence of diabetic neuropathy, peripheral or autonomic, should be remembered and diagnosed as a pejorative condition, seriously influencing the evolution of lesions. Because the sequelae of this complication should be seriously invalidating and even life threatening, all the concomitant pathologies and associated events should be carefully considered and adequately treated.

Independently from the age of the subject, every effort should be done to warrant the best care, preventive measures and treatment to the aged persons suffering from diabetes, having as the main target the higher degree of wellbeing and personal autonomy for the longer period possible.

Anna Giulia Cattaneo, Università dell'Insubria, DBSM, Via J-H Dunant 3, 21100 Varese

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