Amputation should be considered when part of a limb is dead, deadly or a dead loss.
Arterial occlusion or stenosis, if sufficiently severe, will lead to tissue infarction with putrefaction of macroscopic portions of tissue (gangrene). The occlusion may be in major vessels (atherosclerotic or embolic occlusions) or in small peripheral vessels (diabetes, Buerger’s disease, Raynaud’s disease, inadvertent intra-arterial injection, ergotism). If the obstruction cannot be reversed and the symptoms are severe, amputation is indicated.
Moist gangrene with its accompanying putrefaction and infection is dangerous, for the infection spreads to surrounding viable tissues, and cellulitis with severe toxaemia and overwhelming systemic infection can occur. Amputation is indicated as a life saving operation. Antibiotic cover should be broad and massive. Other life-threatening situations for which amputation may be required include gas gangrene (as opposed to simple gas infection,), neoplasm (such as osteogenic sarcoma) and arteriovenous fistula.
This applies to the following:
• severe laceration and fracture with partial amputation due to the trauma of road accident or bomb-blast injury (e.g. mines);
• severe contracture or paralysis, e.g. poliomyelitis, may make the limb impossible to use, and may hinder walking or any movement. Amputation can improve mobility;
• severe rest pain without gangrene in a patient with an ischaemic foot may be an indication for amputation because of the relentless severity of the pain. Amputation under those circumstances can improve the quality of life.
In patients with small-vessel disease (diabetes and Buerger’s disease), gangrene of the toes occurs with relatively good blood supply to the surrounding tissues. Therefore, local amputation of the toe can result in healing.
In diabetic patients:
• infection tends to track up the tendon sheath;
• infection tends to recur if the wound is closed;
• neuropathy often makes early mobility possible because of lack of pain.
For these reasons, when the metatarsophalangeal joint region is involved in diabetes, ‘ray’ excision is recommended, taking part of the metatarsal and cutting tendons back. The wound should not be sutured but loosely packed with gauze soaked in an antiseptic solution such as proflavine. Early mobility aids drainage provided cellulitis is not present. For less extensive gangrene, if amputation is taken through a joint, healing is improved by removing the cartilage from the joint surface.
Transmetatarsal amputation can be used in similar circumstances, where several toes are affected and irreversible ischaemia has extended to the forefoot, as in Buerger’s disease; a viable long plantar flap is essential for this operation to heal successfully.
Preoperative preparation/informed consent
The patient should, whenever possible, be given time to come to terms with the inevitability of amputation and, ideally, once the alternatives between a painful useless limb or a painless useful (artificial) one are explained, the patient will make the final decision. This approach to the matter prevents the patient feeling that the loss of the limb is being imposed, possibly making him or her less positive in attitude to retraining. In gangrene of the foot, especially with ‘skip’ areas, this is the time for explanation of, and consent for, above-knee amputation should an attempt at below-knee section prove inadvisable on account of inadequate blood supply to the flaps. The general condition of the patient needs to be maintained and/or improved, e.g. anaemia corrected and pain controlled.
Physiotherapy before the operation enables the patient to get used to the exercises that will prevent muscle wasting and flexion deformity of the hip.
Antibiotics should be given with the premedication to prevent clostridial infection, particularly in above-knee amputations.
Analgesia. The appropriate level of analgesia should be maintained up to the time of operation.
Assessment of joints. Flexion contracture or severe arthritis may influence the level of amputation and/or the final degree of mobility.
Choice of operation
Where good limb-fitting facilities exist, above- or below-knee amputations are preferable because the best cosmetic and functional results can be obtained by the cone-bearing amputation stumps. [Note the words ‘cone-bearing’. The term conical stump is reserved for an entirely different pathological entity — that which occurs when the growing humerus (or tibia), following amputation in a child, stretches the stump tissues and skin into an unsightly cone. (Main growth occurs in the epiphyses located ‘toward the knee and away from the elbow’.)] If limb-fitting facilities are limited, end-bearing amputation may be preferable (Syme’s, through-knee, Gritti—Stokes) so that simple prostheses (peg leg or simple boot) can be used. Syme’s amputations are not suitable for severely ischaemic atherosclerotic limbs because of the poor healing of the heel flap.
Cone-bearing amputations. For above- or below-knee amputations, with good stump shape and limb-fitting facilities, it is possible to have a prosthesis held in place simply by suction, without any cumbersome and unsightly straps.
• The stump must be of sufficient length to give the required leverage: below the knee — not less than 8 cm (preferably 10—12 cm); above the knee — not less than 20 cm.
• There must be room for the artificial joint (the stump must not be too long); above the knee ideally 12 cm proximal to the knee joint and below the knee 8 cm proximal to the ankle joint are needed for the mechanism.
A below-knee amputation is much better than an above-knee (or Gritti—Stokes) amputation in terms of eventual mobility. Every attempt should be made to preserve the knee joint if the extent of ischaemia or trauma allows this.
Two types of skin flap are commonly used: long posterior flap and skew flap. Skew flaps were described by K.P Robinson. Whatever method is chosen it is wise to remember the old rule that the total length of flap or flaps need to be at least one and a half times the diameter of the leg at the point of bone section.
Long posterior flap below-knee amputation. In cases of trauma a tourniquet is applied at the thigh, but not in cases of ischaemia. Anteriorly, the incision is deepened to bone and the lateral and posterior incisions are fashioned to leave the bulk of the gastrocnemius muscle attached to the flap, muscle and flap being transected together at the same level. If bleeding is inadequate, the amputation is refashioned at a higher level. Blood vessels are identified and ligated. Nerves are not clamped but pulled down gently and transected as high as possible. Vessels in nerves are ligated. The fibula is divided 2 cm proximal to the level of tibial division using bone cutters, the skin and muscle being retracted to avoid damage. The tibia is cleared and transected at the desired level, the anterior aspect of the bone being sawn obliquely before the cross-cut is made. This, with filing, gives an anterior smooth bevel which prevents pressure necrosis of the flap. The long muscle/skin flap is tapered after removing the bulk of soleus muscle (most of the gastrocnemius may be left), the area is washed with saline to remove bone fragments and the muscle and fascia are sutured with catgut or Dexon to bring the flap over the bone ends. A suction drain is placed deep to the muscle and brought out through a stab incision in the skin. The skin flap should lie in place with all tension taken by the deep sutures. Interrupted skin sutures are inserted. The drain can be attached to the skin by adhesive tape instead of sutures, allowing its removal without the need to take down the stump dressing. Gauze, wool and crêpe bandages make up the stump dressing.
Skew flaps.This form of below-knee amputation seeks to make use of anatomical knowledge of the skin blood supply. Equally long flaps are developed; they join anteriorly 2.5 cm from the tibial crest, overlying the anterior tibial compartment, and posteriorly at the exact opposite point on the circumference of the leg. After division of bone and muscle in a fashion similar to that above, the gastrocnemius flap is sutured over the cut bone end to the anterior tibial periosteum with catgut or Dexon. Finally, drainage and skin sutures are inserted and the limb is dressed as in the long posterior flap operation.
The site is chosen as indicated above, but may need to be higher if bleeding is poor on incision of the skin. Curved equal anterior and posterior skin flaps are made of sufficient total length (one and a half times the anterior/posterior diameter of the thigh). Skin, deep fascia and muscle are transected in the same line. Vessels are ligated. The sciatic nerve is pulled down and transected cleanly as high as possible and the accompanying artery ligated. Muscle and skin are retracted, and the bone is cleared and sawn at the point chosen. Haemostasis is achieved. The muscle ends are grouped together over the bone by means. of catgut or Dexon sutures incorporating the fascia. A suction drain deep to the muscle is brought out through the skin clear of the wound and affixed with tape so that removal can takes place without disturbing the stump dressing. The fascia and subcutaneous tissues are further brought together so that the skin can be apposed by interrupted sutures without tension. Gauze, wool and crêpe bandages form the stump dressing.
Gritti—Stokes and through-knee amputations
Gritti—Stokes and through-knee amputations are rarely done nowadays. In the Gritti—Stokes type, the section is transcondylar.
It is essential to preserve the blood supply to the heel flap by meticulous clean dissection of the calcaneum. The tibia and fibula are sectioned as low as possible to the top of the mortice joint. This type of procedure is rarely applicable in patients with occlusive vascular disease.
Postoperative care of an amputation
Diamorphine or other opiates should be given regularly.
Care of the good limb
Attention is focused on the amputation, but a pressure ulcer on the good foot will delay mobilisation, despite satisfactory healing of the stump. The use of a cradle to keep the weight of bed clothes off the foot and pressure area care are adjuncts to good nursing care.
Exercises and mobilisation
Immediately, the prevention of flexion deformity can be achieved by the use of a cloth placed over the stump with sand bags on each side to weight it down. Once the drain has been removed, exercises are started to build up muscle power and co-ordination. A stump bandage is applied each day to mould the shape of the stump. Mobility is progressively increased with walking between bars and the use of an inflatable artificial limb which allows weight-bearing to be started before a pylon or temporary artificial limb is read. It is emphasised that the whole episode in the patient’s life should be conducted in an attitude of promotion through the stages towards full independence. Early assessment of the home (part of the whole programme) allows time for minor alterations, such as the addition of stair rails, movement of furniture to give support near doors, and clearance in confined passages.
Early complications include the following: reactionary haemorrhage, which requires return to the theatre for operative haemostasis; a haematoma, which requires evacuation; and infection, usually from a haematoma. Any abscess must be drained. Depending upon the sensitivity reactions of the organisms cultured, the appropriate antibiotics are given. Gas gangrene can occur in a midthigh stump, the organisms coming from contamination by the patient’s faeces. Wound dehiscence and gangrene of the flaps are due to ischaemia; a higher amputation may well be necessary. Amputees are at risk of deep vein thrombosis and pulmonary embolism in the early postoperative period. Prophylaxis with subcutaneous heparin 5000 units twice daily is advised for several weeks after operation.
Late.Pain is sometimes a problem due to unresolved infection (sinus, osteitis, sequestrum), a bone spur, a scar adherent to bone, an amputation neuroma from the outgrowth of nerve fibrils which become attached to skin, muscle or fibrous tissue, or a phantom limb.
Phantom pain. Patients frequently remark that they can feel the amputated limb and sometimes that it is painful. The surgeon’s attitude should be one of firm reassurance that this sensation will disappear. Other late complications include ulceration of the stump due to pressure effects of the prosthesis or increased ischaemia. Rarely, an ulcer is artefactual. Some patients are troubled by cold and discoloured stumps, especially during the winter.
Related Post :
No comments yet.