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Why are most ulcers located on the leg?

For phlebologists whose main job is to fight against gravity every day, the correct answer to this question is obvious. Venous return in the upright human subject, which is so susceptible to faults and often fails, operates through a delicate cooperation between joint-, skinand muscle activity and venous valves, constantly working against gravity. Phlebologists are so familiar with this problem that they sometimes tend to accept the simplified view that all ulcers that are not arterial are ‘venous’. In fact, only those ulcers in which venous pathology (reflux, obstruction or both) can be demonstrated should be called ‘venous’. A leg ulcer is not a disease per se but a symptom of an underlying disorder. This is not just of academic interest but has major practical consequences when it comes to treatment: arterial or vasculitic ulcers need different therapy than ulcers due to haematological, dermatological or infectious disorders. However, all these ulcers have one thing in common: they are situated on the lower leg and frequently mimic venous ulceration. The causative factor is gravity, which increases venous pressure with all its implications on the microcirculation, even in the absence of venous reflux or obstruction. Leg ulcers in patients with morbid obesity are striking examples of this situation. Following the updated clinical, aetiological, anatomical and pathological terminology, those cases in which neither venous reflux nor obstruction can be demonstrated may be termed as C6 En An Pn (the descriptor ‘n’ has been proposed for cases where no venous abnormality can be identified). The vast majority of leg ulcers present with venous refluxes, in the superficial veins, the deep veins or both, which can clearly be demonstrated by duplex ultrasound. Abolishing these refluxes is increasingly being accepted, at least after ulcer healing in order to prevent recurrence. Even very conservative surgeons are starting to consider saphenous vein ablation in patients without major visible varicosities, not just recommending that such patients consult wound-healing specialists for local treatment. Different endovenous procedures, including foam sclerotherapy, may be very effective. However, venous-like leg ulcers without reflux do exist, not only in obese patients. How frequent is this condition? After excluding arterial disease, the Swedish dermatologist Bjellerup was unable to detect refluxes in 70 out of 332 leg ulcers (21%) by hand-held Doppler and used the term ‘hydrostatic ulcer’ for these cases. Using duplex sonography, Labropoulos et al. investigated a more surgically selected population of 710 patients that ‘presented with signs and symptoms of chronic venous disease’ and reported a prevalence of leg ulcers of only 2.1%, in which no relationship to arterial and venous disease was demonstrated. The underlying causes were vasculitis, neoplasia, metabolic disorders, infection and other rare causes. Obviously, neither ‘hydrostatic ulcers’ nor banal, ‘post-traumatic ulcers’ were seen, although they are a typical model for the problem discussed. One of the reasons why ulcers are more often localized on the leg than in other body regions is because the legs are more exposed to trauma. Daily experience tells us that such wounds after trauma may be difficult to heal, especially in elderly people, even with normal arterial and venous macrocirculation, merely because of the problem of compromised skin microcirculation due to gravity. The practical consequences in such ‘nonvascular’ ulcers showing normal ankle brachial pressure index (ABPI) and no venous refluxes are two-fold: