Amputation
Amputation
should be considered when part of a limb is dead, deadly or a dead loss.
Dead
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.
Deadly
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, Chapter 8), neoplasm (such as osteogenic sarcoma) and
arteriovenous fistula.
Dead loss
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) (Chapter 19);
•
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 (Fig. 15.39). 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
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 (Fig. 15.40).
Major amputation
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
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
(Chapter 8), particularly in above-knee amputations.
Analgesia.
The appropriate level of analgesia should be maintained up to the time of
operation (and see Postoperative analgesia in Chapter 6).
Assessment
of joints. Flexion contracture or severe arthritis may influence the
level of amputation and/or the final degree of mobility.
Choice of operation
(Fig. 15.41)
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
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 (Fig. 15.42). 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 crępe 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
Above-knee amputations
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 crępe 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.
Syme’s amputation
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
Pain
relief
Diamorphine
or other opiates should be given regularly (Chapter 6).
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 (Fig. 15.43). 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 (Fig. 12.16). Some patients are
troubled by cold and discoloured stumps, especially during the winter.