1. GANGRENE

2. It implies death of macroscopic portions of tissue; the term necrosis may be used synonymously.

3. Clinical features
A gangrenous part lacks arterial pulsation, venous return, capillary response to pressure, sensation, warmth and function.
The colour of the part changes through a variety of shades according to circumstances (pallor, dusky grey, mottled, purple) until finally taking on the characteristic dark-brown, greenish-black or black appearance, which is caused by the disintegration of hemoglobin and the formation of Iron Sulphide.

4. Dry gangrene occurs when the tissues are desiccated by gradual slowing of the bloodstream; it is typically the result of atheromatous occlusion of arteries. The affected part becomes dry and wrinkled, discoloured from disintegration of hemoglobin, and greasy to the touch.
Moist gangrene occurs when infection and putrefaction are present; the affected part becomes swollen and discoloured and the epidermis may be raised in blebs. Crepitus may be palpated as a result of infection by gas-forming organisms. This situation is quite common in diabetics.

5. Separation of gangrene
A zone of demarcation between the truly viable and the dead or dying tissue will eventually appear. Separation is achieved by the development of a layer of granulation tissue, which forms between the dead and the living parts.
In dry gangrene, if the blood supply of the proximal tissues is adequate, the final line of demarcation appears in a matter of days and separation occurs neatly and with the minimum of infection (so called separation by aseptic ulceration).
In moist gangrene there is significant infection and suppuration extends into the neighbouring living tissue, thereby causing the final line of demarcation to be more proximal than in dry gangrene (separation by septic ulceration). This is why dry gangrene must be kept as dry and aseptic as possible, and why every effort should be made to convert moist gangrene into the dry type.

6. Treatment of gangrene
this depends on the blood supply proximal to the gangrene. Sometimes this can be improved by radiological or surgical intervention.
A good blood supply may allow a conservative excision or distal amputation, avoiding a major ablation. Conservative treatment involves keeping the affected part absolutely dry. Exposure to the air and the use of a fan may assist in the desiccation process and may relieve pain.

7. The limb must not be heated. Local pressure areas, e. g
The limb must not be heated. Local pressure areas, e.g. the skin of the heel or the malleoli, must be protected if fresh patches of gangrene are not to occur in these places. Foam blocks and air beds are useful preventative aids. Occasionally, the lifting of a crust or the removal of hard skin helps demarcation or releases pus and relieves pain.
a proximal life-saving amputation is required for rapidly spreading symptomatic gangrene and gas gangrene.

8. Specific varieties of gangrene
1)Diabetic gangrene
Its related to three factors:
trophic changes from peripheral neuropathy,
ischaemia as a result of atheroma,
and low resistance to infection because of excess sugar in the tissues
Treatment :
bringing the diabetes under control by diet and drugs.
The gangrene is treated as described above.
A rapid spread of infection requires drainage by incision and the removal of any obviously dead tissue.

9. Diabetic gangrene.

10. 2)Bedsores
A bedsore is gangrene caused by local pressure . predisposed by five factors:
pressure, injury, anaemia, malnutrition and moisture.
They can appear and extend rapidly in immobile patients and in those with debilitating illness.
Prophylactic measures :
the avoidance of pressure over bony prominences by the use of foam blocks or similar, regular turning, and nursing on specially designed beds.
Injury from wrinkled sheets and maceration of the skin by sweat, urine or pus must be prevented by skilled nursing and the use of an adhesive film dressing.
The affected area must be kept dry and an aerosol silicone spray may be used.
Once pressure sores develop, they are difficult to heal. They may be treated by lotions or by exposure to keep them as dry as possible. They should be kept clean and debrided if necessary.
Advice from a plastic surgeon should be sought for major lesions; rotation flaps can be effective.

11. Bedsores typically appear over areas exposed to pressure

12. 3)Drug abuse
Inadvertent arterial injection of drugs has become common in many countries with significant numbers of drug addicts.
Usually, the femoral artery in the groin is involved and presentation is with pain and mottling distally in the leg.
Fortunately, most cases resolve and progression to gangrene is rare.
It should be remembered that many of these patients carry the human immunodeficiency virus and/or various hepatitis viruses.

13. caused by exposure to cold.
4)Frostbite
caused by exposure to cold.
seen both in climbers at high altidudes and in the elderly during cold.
Vessel walls are damaged, leading to transudation and oedema.
The sufferer experiences a severe burning pain in the affected part, which later assumes a waxy appearance as the pain disappears. Blistering and then gangrene follow.
Frostbitten parts must be warmed gradually; any temperature higher than that of the body is detrimental. The part should be wrapped in cotton wool and kept at rest. Friction, e.g. rubbing with snow, may damage already devitalised tissues. Warm drinks and clothing should be provided and powerful analgesics given to relieve the pain that heralds the return of circulation.
Amputations should be conservative.

14. Frostbite of the foot Note the clear demarcation

15. Frostbite of the middle finger in the same patient
Frostbite of the middle finger in the same patient. The index finger was lost 2 years before, also from frostbite.

16. 5) Venous gangrene
Although deep vein thrombosis is common, venous gangrene is surprisingly rare. It occurs when the circulation of a limb (usually the leg) is disrupted by overwhelming outflow obstruction and this requires massive deep vein thrombosis at a proximal site.
Treatment
in those at risk is by full anticoagulation with heparin
effective elevation of the swollen leg, preferably with the head and trunk level.
Some would advocate venous thrombectomy in extreme circumstances using a Fogarty catheter.

17. AMPUTATION

18. Its resection of part or all of a limb.

19. INDICATIONS (1) Dead, (2) Dangerous , (3) Damned nuisance:
Dead (or dying) Peripheral vascular disease accounts for almost 90 % of all amputations. Other causes of limb death are severe trauma, burns and frostbite.
Dangerous ‘Dangerous’ disorders are malignant tumours, potentially lethal sepsis and crush injury.
Damned nuisance Retaining the limb may be worse than having no limb at all. This may be because of:
(1) pain
(2) gross malformation
(3) recurrent sepsis or
(4) severe loss of function.

20. COMPLICATIONS OF AMPUTATION STUMPS
EARLY COMPLICATIONS
In addition to the complications of any operation (especially secondary haemorrhage), there are two special hazards:
Breakdown of skin flaps. This may be due to ischaemia, suturing under excess tension or (in below-knee amputations) an unduly long tibia pressing against the flap.
Gas gangrene . Clostridia and spores from the perineum may infect a high above-knee amputation (or re-amputation), especially if performed through ischaemic tissue.

21. LATE COMPLICATIONS
Skin Eczema is common, and tender purulent lumps may develop in the groin. A rest from the prosthesis is indicated.
Ulceration is usually due to poor circulation, and re- amputation at a higher level is then necessary. If, however, the circulation is satisfactory and the skin around an ulcer is healthy, it may be sufficient to excise 2.5 cm of bone and re-suture.
Muscle If too much muscle is left at the end of the stump, the resulting unstable ‘cushion’ induces a feeling of insecurity that may prevent proper use of a prosthesis; if so, the excess soft tissue must be excised.
Blood supply Poor circulation gives a cold, blue stump that is liable to ulcerate. This problem chiefly arises with below-knee amputations and often re-amputation is necessary.

22. Nerve A cut nerve always forms a neuroma and occasionally this is painful and tender. Excising 3 cm of the nerve above the neuroma sometimes succeeds.
‘Phantom limb’ the feeling that the amputated limb is still present. appear to have greater significance in those who also have features of depressive symptoms. The patient should be warned of the possibility; eventually the feeling recedes or disappears but, in some, long-term medication may be needed. A painful phantom limb is very difficult to treat.
Joint The joint above an amputation may be stiff or deformed.
Bone A spur often forms at the end of the bone, but is usually painless. If there has been infection, however, the spur may be large and painful and it may be necessary to excise the end of the bone with the spur.

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