Short Notes in Plastic Surgery

September 30, 2011

Chronic Venous Ulcers of the Lower Leg

Filed under: Chapter 16 — mthatte @ 4:19 am

9. In the past there seemed to be a fixed population of intractable ulcers around the ankle which attended the out patient clinic or were admitted to an indoor facility in a plastic surgical unit but they now seem to be reducing in numbers. This might have something to do with the development of vascular surgery as a speciality.
10. With improved vascular imaging, both indirect (dopplers with ultrasound) and direct (radiological contrast studies) and greater possibilities to access the lumens of peripheral arteries, a small percentage of the so called venous ulcers are now proving to arise out of arterial insufficiency, and a fair percentage of these can be cured by way of vascular interventions and revascularization (atherectomy, endarteriectomy, angioplasty and stenting). While it is sound clinical medicine to palpate the peripheral pulses in the leg, the presence of such a pulse may not be enough to estimate the amount of flow. Findings of a feeble or reduced pulse are merely subjective impressions and in any long standing ulcer in the lower leg, some objective evidence of the volume of arterial flow needs to be obtained. Should there be a block in the arterial side, the treatment of this block must remain a priority before veins become the focus of investigation and treatment.
11. It is assumed while writing this section that the traditional methods of treating such ulcers with rest, elevation, bacterial cultures and suitable antibiotics, compression bandages, as well as biological dressings are being tried and will continue to be implemented as the arterial and venous systems get investigated and treated.
12. Venous ulcers are caused by venous hypertension in the superficial saphenous venous system. This system supports its column of blood against gravity by a succession of unidirectional valves along its length, ending near the sapheno-femoral junction, which too has a valve. These valves open in the cephalad direction. The blood from this system also gets drained to a deeper venous system in the calf muscles which, because of their pumping action, create a negative pressure from time to time within them. This drainage is effected via numerous short veins which pierce the deep fascia and are therefore called perforators. The valves within these perforators open towards the deeper system of veins. Any incompetence in either the vertical or the transverse perforator system leads to stagnation of blood in the superficial system leading to venous hypertension. Age has an important bearing on the incompetency of valves. The incompetence of the perforating system may be inherent or can happen following thrombosis of deeper veins which, when they get recanalised, () leads to holes being punched indiscriminately in the valves. Deep vein thrombosis of any duration also means that the drainage into them from the superficial system gets choked up. At the present time treatment of established deep vein thrombosis is not possible by any surgical method but early diagnosis can prevent its spread with the help of life-long treatment with anti-coagulants.
13. More important from the plastic surgeons’ point of view is how venous hypertension leads to ulceration and the consequences of this chronic ulceration locally. Soft tissue has poor tolerance to the extrusion of all intra-vascular substances contained in blood. This leads to irritation and inflammation and molecular necrosis. But, unlike in other parts of the body, here the process of healing is prevented because the extrusion persists and the venous stagnation will not allow proper scavenging of the products of inflammation. Local inflammation may lead to lymphatic obstruction as well. Chronic ulceration leads to scarring in the bed of the ulcer as dermis is slowly destroyed together with the sparse fat and, to add to the difficult situation, most of these ulcers are located in areas where bones and tendons are placed subcutaneously with only fascia intervening. In older, infirm people or diabetics there are additional factors which will retard healing.
14. While the standard surgical maxim states that removal of a cause should allow automatic healing, at least in some cases ulcers following both arterial obstruction as well as venous hypertension cannot follow this rule because of the scarring that has occurred in the bed of these ulcers during their chronic phase. The apparent healing by a way of tenuous epithelialisation is also vulnerable to trauma because of the ulcer’s location in the lower leg.
15. Therefore if the ulcer persists even after the arterial or venous cause has been properly treated by the concerned specialists, and the conventional treatment mentioned in point 3 does not succeed in healing the ulcer, it should preferably be biopsied to rule out a malignancy. Assuming this is negative, some form of skin cover can then be deemed to be necessary.
16. These wounds rarely ever granulate satisfactorily on their own, and their preparation for split skin grafting usually requires scraping or tangential excision or a formal excision up to some depth and also beyond the ulcer because the capillary network in the scarred area will have been lost through thrombosis. Even then the bed might remain unreliable and recourse might have to be taken to including normal skin by way of wide excision for a more reliable take of the graft. The graft on the original site of the ulcer then has the advantage of bridging from the graft put on the unaffected excised area.
17. Empirical evidence suggests that patients treated adequately for venous ulcers both by way of surgery on veins as well as proper skin cover continue to need elastic support to the legs for the rest of their lives with graduated compression stockings.
18. Only very occasionally, when the ulcers are deep with exposed bones and tendons with little hope of granulation creeping over these structures, flap cover becomes necessary. But while planning a flap the following facts need to be considered.
a. Venous ulcers are common in the elderly patient and there might be concomitant arterial disease and deficiency which requires to be looked into before skin cover is finally undertaken.
b. In several of these patients, if stripping and/or ligation or laser ablation of perforators has been performed, venous drainage may not be ideal.
c. Varicose veins are not infrequently bilateral and there might be problems in the veins of the contra-lateral leg including incipient changes in the skin. It is also likely that when a flap is borrowed from this area the defect created and now covered with a split skin graft may be vulnerable to ulceration over the years.
d. A flap positioned in an area of less than ideal drainage and/or arterial supply will not have a sturdy long term existence.
19. Once these conditions are borne in mind, a free flap, a cross leg flap or a turnover flap can be planned. Other local flaps have poor results in this area.
The author is grateful for the inputs given by Paresh Pai, a vascular surgeon from Mumbai for this chapter.

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