56. Amputation
From Primary Surgery
56.1 The general method for amputations.
Lower limb amputation is required much more frequently than for the upper limb. When doing an amputation retain as much function as possible which often means the retention of length in particular aim for the longest possible stump of an arm. Every centimetre is useful. If at all possilbe the elbow which can be used as a hook or any portion of the wrist.
The amputated leg must have a prosthesis which will bear weight. There are a limited number of these, and the stumps for them are standardized. So always do one of the standard leg amputations. There are three technological grades of prosthesis; of these the third is not necessarily the worst. A patient might have: (1) A sophisticated modern prosthesis costing $300 or more. (2) A simpler modern prosthesis costing $30, such as one of those developed by Huckstep for polio (26.2), which any bicycle mechanic can mend. Or, (3) the patient might have a traditional prosthesis, such as a pylon, a peg leg, or elephant boot. Don't despise these; when well made they last longer than any of the others, and are better than a modern prosthesis for working in the fields.
A leg prosthesis can: (1) Have a cup to bear weight on the sides of the stump, in which case the scar should be at the end. (2) Bear weight on the end of the stump, in which case the scar should be posterior. (3) Have a modern total contact socket in which the position of the scar is unimportant. Limb fitting centres vary in their scope and preferences, so visit your local one and find out what they like. A good prosthetist can fit any well constructed stump with a prosthesis.
IN THE ARM CONSERVE EVERY CENTIMETRE
IN THE LEG DO A STANDARD AMPUTATION
In the abdomen poor surgical craftsmenship is hidden, but on an amputation stump it is there for everyone to see. In a perfect stump: (1) The scar is not exposed to pressure. (2) The skin slides easily over the bone. (3) The skin is not infolded. (4) There is no redundant soft tissue. (5) There is no protruding spur of bone. (6) The stump is painless. And, (7) the wound has healed by first intention. Most amputation stumps should be conical.
Fish mouth flaps As a general rule, cut the fish mouth flaps shown in Fig. 56-4. The alternative is a guillotine amputation, as described in Section 56.2. Fish mouth flaps must be long enough to cover the soft tissues of the stump, but not be so
long that their blood supply is inadequate and they necrose. If the flaps are equal, the scar will come at the end of a stump. If they are unequal the scar can come at the front or the back. Try to place the scar where it is not going to be pressed on. In the hand and the foot, place it dorsally. Higher up the arm the scar can be anywhere. In the leg, its site depends on the kind of prosthesis the patient is to have-end bearing, side bear - ing, or total contact. In the lower arm and leg transverse scars are better than anteroposterior ones because they do not get drawn up between the two bones.
Immediate suture or delayed primary closure? Delayed primary closure is always wise: (1) If the patient's limb is already infected, or might easily become so. (2) In all battle casualties. (3) If there is much soft tissue injury. (4) If the blood supply of the stump is uncertain. If you decide on delayed primary closure, cut the flaps long, to allow them to retract. Leave the patient's muscle and fascia unsutured, bandage the skin flaps over dry gauze swabs, don't put in any stitches, and bring him back to the theatre 3 to 5 days later. If his wound is not infected, close it. If it is infected, leave the flaps open for a week or longer, and close it later by secondary suture.
Postoperative care. Much depends on what happens to a patient after he leaves the theatre. His leg stump must be prepared for the prosthesis, and he need, to be taught how to use it. Firm bandaging will hasten to conversion of his stump from a bulky cylinder to a narrow cone, and exercises will strengthen its remaining muscles. So, give the stump something to do. After a lower leg amputation he can learn to kick a large rubber ball about.
How do amputations differ in children? Most of the same principles apply in a child. Disarticulate a joint if you can, especially at his knee, because this will preserve its epiphysis. Removing a limb by amputating through the shaft of a bone produces an effect which varies with the site. It can either cause excessive bony overgrowth with the need for a revision amputations later, or a short stump.
- SAW, amputation, with hinged back, 230 mm, (a) saw, one only. (b) Spare blades for the above, three only. The back of the saw stiffens it during the early part of the cut, but can be hinged back later to let the saw pass through.
SAW, Gigli, (a) pair of handles, one pair only. (b) Saw blades, 30 cm, 4 Only. A Gigli bone saw is a piece of wire with sharp teeth on it which you pull to and fro between two handles. Use it to cut bone in awkward places.
- KNIFE, amputation, L iston 180 mm, one only. If you don't have an amputation knife, sharpen a long kitchen knife and use that.
Here is the sequence of steps for all amputations. they are not repeated in the instructions for the specific sites described later. Follow the steps in the order in which we give them here.
GENERAL METHOD FOR AMPUTATIONS
INDICATIONS (1) An arm which is so severely injured that there is no chance of recovery of any part of the hand, fingers or thumb. (2) A leg which is so severely injured that you cannot restore the continuity of its vessels or nerves, especially when there is gross contamination or severe muscle or skin loss. Loss of bone alone without nerve or vascular injury does not usually justify amputation. (3) Gas gangrene. (4) Established gangrene due to vascular injury. (5) Continued infection with severe bone or nerve injury. (6) Secondary haemorrhage if all other measures fail. (7) Multiple in injuries in a gravely ill shocked patient. Amputation may be the simplest and fastest way of removing large amounts of damaged muscle, and so saving his life. (8) Occasionally also for epitheliomas, bone tumours, or snake bites.
CAUTION ! If you amputate for a malignancy, biospy it first.
ANAESTHESIA Relaxation is unnecessary Ketamine is adequate (8.1). Subarachnoid (spinal) anaesthesia (A 7.4) is particularly useful for below knee amputations. Nobody likes hearing their bones being sawn through, so if a patient is conscious premeditate him heavily.
TOURNIQUET Use a tourniquet (3.8), except when you are amputating for ischaemia. Bleeding is a useful sign that a muscle is alive. If it is dead you may need to amputate higher up. A tourniquet may also make ischaemia worse. Release it before you suture the muscles, so that you can tie the bleeding vessels before you cover them. When you use a tourniquet, exsanguinate the patient's limb with an Esmarch bandage first (3.3), except when you are amputating for sepsis or malignancy which it may spread.
CAUTION ! Don't rely on digital pressure over the main vessels to control bleeding.
CUTTING FISH MOUTH FLAPS FOR AN AMPUTATI0N
Decide where you are going to saw the bone (the point of section) and plan the flaps in relation to that point. Place the angle of the fish mouth at the site of bone section. Mark them out carefully with methylene blue or scratch marks. If the flaps are equal, make the length of each of them equal to 3/4 of the diameter of the limb as in A, Fig. 56-4. If the flaps are unequal, make the longer flap equal to the diameter of the limb, and the shorter one equal to half its diameter, as in B. Cut through the skin down to the deep fascia, and reflect this up with the skin as part of the flap. The shin of the stump will need to slide over the deep fascia, so keep them together. If you are amputating for ischaemia ’’minimize trauma to the /laps’’. Handle them with stay sutures rather than with forceps.
CAUTION ! (1) Start by making fish mouth flaps long. You can always trim them if they are too long later, but you cannot lengthen them if they are too short. (2) Cut them round not pointed. (3) Their combined length should be equal one and a half times the diameter of the limb at the site of bone section. (4) If you are amputating a severely lacerated limb, try to preserve all viable skin.
CONTROLLING BLEEDING DURING AN AMPUTATION
Early in the operation, find the major arteries and veins. Tie them separately with double transfixion ligatures (3.2) preferably linen. Then cut them between these ligatures. Later, after you have removed the limb, release the tourniquet slowly and tie the remaining smaller vessels. If the cut ends of the muscles bleed furiously, apply packs for five minutes. If the amputation is very high you may have to expose the main artery higher up at one of the classical sites described i n Sections 3.4 to 3.7. CAUTION ! (1) If you don't use a tourniquet, find and tie the major vessels ’’before’’ you cut them. (2) Don't clamp them, cut
them and then try to tie them. If a clamp slips there will be massive bleeding. (3) Careful haemostatsis of the stump is essential. If a clot forms, it is easily infected.
CUTTING MUSCLES DURING AN AMPUTATION
Muscles always contract, after you have cut them. So cut them transversely about 5 cm distal the site of bone section. Leave them a little longer if you are using delayed primary closure, because they will have more time to shrink.
Use a long sharp amputation knife or carving knife to cut the muscles straight down to the bone. Don't use a scalpel which makes many small cuts, and leaves shreds of injured muscle.
Sew the cut ends of the muscle securely together over the cut end of the bone, so that they cushion it, and are better able to move over the stump. Cut them long enough for this but don't leave so much muscle that the stump becomes bulbous.
CUTTING NERVES DURING AN AMPUTATION
Don't tie nerves. A painful neuroma will result, especially in the fingers. Instead, gently pull each nerve into the wound, cut it cleanly with a knife, then let it retract above the amputation site.
SAWING BONES DURING AN AMPUTATION
Clear the muscle from the site of section, and incise the periosteum all round it. Reflect this distally for one or two centimetres with the muscles, so as to leave bare bone for the saw.
Use a saw with well set teeth. Start by steadying it with your thumb. Draw it towards you across the bone a few times. When it has made a good slot in the bone, start sawing hard. Ask an assistant to hold the patient's limb to steady it, and pull gently to prevent the saw locking in the bone and splitting it. Finally, remove any spikes with bone forceps, and bevel any protruding edges with a coarse rasp.
CAUTION! (1) Don't reflect the periosteum proximally, because the bone under it will die, and a ring sequestrum will form. (2) Don't damage the surrounding muscle with the saw. Cut the muscle first, or retract it well out of the way with a towel wrapped round the limb, as in Fig. 56-5, then saw. (3) Bone dust from the saw acts as a foreign body, so wash it away with saline.
DEALING WITH FAT DURING AN AMPUTATION
If a patient's limb is very fat, cautiously remove as much subcutaneous fat as is necessary. Don't remove too much, especially near the edges of the flap, or it may necrose. Learn to design flaps so that they come together accurately without dog ears' If they form, leave them, they will soon disappear.
CLOSING THE WOUND AFTER AN AMPUTATION
SUTURES As indicated above, delayed primary suture will be safer. Suture the skin and deep fascia separately. Close the flaps without tension, without leaving gaping areas between the sutures, and without tying them too tight.
DRAINS If you use delayed primary suture, no drains are necessary. If you close a stump by immediate suture, insert a drain under the muscle flap (if there is one) over the end of the bone. If possible, use a suction drain. If you don't have one, insert a 2 cm corrugated rubber drain. Bring both its ends
out loosely through the two ends of the incision as shown in F, Fig. 56-4.
If no blood is oozing from the drains, remove them at 48 hours, if blood continues to flow, leave them for a further 24 hours.
DRESSINGS Dress the stump firmly, but not too tightly. A plaster covering will make it more comfortable. Change the dressings at 48 hours.
POSTOPERATIVE CARE FOR AN AMPUTATION
As soon as the skin has healed, bandage the stump. For the leg, sew two 15 cm crepe bandages end-to-end. For the arm, use one 10 cm bandage. Roll the bandage tightly, then wind it round the stump. Apply more tension to the end of the stump, than to its base, or it will become bulbous. Reapply the bandage several times a day until the prosthesis is fitted. Don't use adhesive strapping, or you may tear the skin of the stump.
THE FURTHER MANAGEMENT OF AN AMPUTATION
Read on for: guillotine amputations (56.2), amputating for gangrene (56.3), amputating through the upper arm and elbow (56.4), the lower arm and wrist (56.5), above the knee (56.6), through the knee (56.7), below the knee (56.8), Syme's amputation (56.9), and amputating through the foot and toes (56.10).
DIFFICULTIES WITH AMPUTATIONS
If a patient's LIMB IS TRAPPED in a falling building, you may have to amputate it on the spot. Give him ketamine or intravenous morphine (8.6), or infiltrate his tissues with a local anaesthetic. Control bleeding by pressing on the pressure point, or with a tourniquet and then tie the vessels. Cut through his trapped limb with an amputation knife and a saw, as far distally as you can, and apply a firm pressure dressing to the stump. Transfer him to hospital for a formal amputation at the next most suitable site higher up his limb, either immediately, or later.
If a patient is SEVERELY SHOCKED, you can do a quick provisional amputation distal to the site of election. Later, when his wound has healed, you can do a definitive amputation with immediate primary closure. He will no longer be shocked, his skin will be normal, and there will be less danger of infection.
If you amputate in an emergency for shock, or sepsis, or to remove a grossly crushed limb, don't do the final amputation until the stump is healing well.
If his STUMP BLEEDS SOME HOURS AFTER THE OPERATION (reactionary haemorrhage), take him back to the theatre, explore his wound, tie the vessels, leave his wound open and sew it up secondarily. To prevent this happening: (1) tie the major vessels carefully, (2) release the tourniquet slowly, (3) control the vessels thoroughly, and (4), apply a pressure dressing.
If his STUMP BLEEDS SOME DAYS LATER (secondary haemorrhage), it is likely to be serious. Explore the wound. In desperation, open it, pack it with dry gauze, and remove the gauze 48 hours later.
If his STUMP BECOMES INFECTED, this may have been your fault. Did you: (1) Close the wound by immediate primary suture, when delayed primary suture would have been wiser? (2) Fail to control bleeding, before closing the flaps, so that the blood clot beneath them has become infected? (3) Strip up the periosteum from the stump so that a ring sequestrum has formed and become infected?
If a PERSISTENT SINUS develops in the stump, explore it; you may find a piece of necrotic tendon, or an area of osteomyelitis. Another possibility is a stitch sinus. If the offending stitch might be securing a vessel, don't remove it until you have tied the vessel higher up. Explore the stump, remove all dead and dying tissue, and pack it ready for secondary closure.
If the FLAPS BREAK DOWN, you probably cut them too short and closed them too tight. Wait until the granulation tissue is fit for grafting and then graft it. The final quality of the skin over the stump will be worse than it would have been if the flaps had survived, and it may break down later. Alternatively, you may have to amputate higher up.
If a PATCH OF GANGRENE forms in a flap, be careful, it may hide a larger area of necrosis underneath. You may be able to trim it away, or you may have to amputate again higher up, especially if a patient's limb is ischaemic. If it is not ischaemic, you may be able to excise the gangrenous area, allow granulations to develop, and apply a split skin graft.
If he has GAS GANGRENE, amputate high up, through his shoulder if need be, and leave the wound open.
If a PROSTHESIS CANNOT BE FITTED, you probably designed the stump wrong. The reasons include: (1) bone adherent to the scar, (2) a spicule of bone sticking out through the skin, (3) a flexion contracture in a below knee or above knee amputation, (4) too short a stump.
CUT FLAPS LONG
REFLECT THE DEEP FASCIA WITH THE SKIN
DELAYED PRIMARY CLOSURE IS SAFER
56.2 Guillotine amputations
If you amputate a severely infected limb, the infection may be spread to the stump, especially if you are amputating for gas gangrene. It will be less likely to do so if you: (1) Cut straight down to the bone all round the limb, and then saw the bone through at the same level, (2) leave the surface unsutured, and (3) revise the amputation later if necessary. A guillotine amputation is quick, and the flaps are less likely to necrose if the blood supply is poor. Some surgeons never use them.
GUILLOTINE AMPUTATIONS Apply a tourniquet. Cut the flaps as far distally as you can, so that you can refashion them later. Cut the patient's skin down to his deep fascia all round his limb 2 cm distal to the site of bone section. Let it retract. Then cut the muscle all round his limb down to the same site.
Tie and cut all the large vessels you meet. Cut all major nerves at least 2 cm proximal to the end of the stump. Dress the patient's stump with vaseline gauze and plenty of dry gauze. Bandage it, and let it granulate. When it has healed, or there is no further risk of infection, either: (1) revise the amputation higher up, or (2) graft it, or (3) refer him.
56.3 Amputating for ischaemic gangrene
Deciding where to amputate can be difficult. The lower you amputate, the greater the chance that the patient will walk again afterwards. But there is also more chance that the tissue through which you amputate will not be viable, so that his stump will become infected or gangrenous. Feel his pulses carefully, if you cannot feel his popliteal pulse, do an above knee amputation.
If his muscles do not look healthy when you cut them, abandon the operation at that site, and amputate higher up. Healthy muscle is a nice bright red, and has a good capillary ooze. Ischaemic muscle is a dusky bluish red, and bleeds little or not at all. The tissues of a diabetic are at particular risk, including those of his other limb. So handle the flaps with your fingers, not with forceps. Protect his other limb during the operation so as to make sure that pressure sores do not form. Control his diabetes as in A 17.7.
When you amputate for ischaemia, always close the wound by delayed primary closure (54.4).
56.4 Amputating through the upper arm and elbow
Save as much of the length of the patient's arm as you can, because he will probably have no prosthesis. If possible, disarticulate his elbow. If you amputate higher up, a convenient place is 18 to 20 cm below his acromion. If you can leave him with a reasonable length of humerus, he can use it to hold things by gripping them against his chest. If you have to amputate very high up, even a very short stump will preserve the outline of his shoulder. If he is to have a prosthesis, don't amputate through the lower 4 cm of his humerus, because it will be difficult to fit.
Remember that his brachial artery lies quite superficially, and is overlapped medially by his biceps.
AMPUTATING THROUGH THE UPPER ARM
For the general method see Section 56.1. Prepare the operation site, and abduct the patient's arm to about 80° on an arm board. Place a block under his arm just proximal to the amputation site. Apply a tourniquet as high as you can.
THE MID UPPER ARM AS AN AMPUTATION SITE
Start proximally at the site of bone section, and mark out equal anterior and posterior skin flaps. Make the length of each flap 3/ of the diameter of his arm at the site of section.
Find, doubly ligate, and cut his brachial artery and vein just above the site of section. Find, gently pull and cut the major nerves so that their ends retract well above the stump.
Cut the anterior muscles 1.5 cm distal to the site of section. Cut the triceps 4 cm distal to the site of section. Cut the periosteum all round the patient's humerus and saw it through. Rasp the end of his humerus smooth. Bevel his triceps to make a thin flap, reflect it anteriorly over the end
of his humerus, and sew it to the anterior muscle and fascia. Release the tourniquet, control bleeding, drain and close the stump as usual (56.1).
THE SUPRACONDYLAR REGION AS AN AMPUTATION SITE
Starting proximally at the site of bone section, mark out equal anterior and posterior skin flaps, each as long as 3/4 of the diameter of the patient's arm at the site of section, as in Fig. 56-8. Find, clamp, tie, and cut his brachial artery and vein just proximal to the site of section. Cut his median, ulnar, and radial nerves at a higher level so their ends retract well above the stump.
Cut the muscles in the anterior compartment of his arm 1.5 cm distal to the site of section. Free the insertion of his triceps tendon from his olecranon. Preserve his triceps fascia and muscle as a long flap.
If he has any hope of an elbow prosthesis, reflect this flap proximally and cut the periosteum all round his humerus at least 4 cm above his elbow joint to allow room for the elbow mechanisms of the prosthesis.
If he has no hope of an elbow prosthesis, leave as much bone as you can. Saw across his humerus at the level you choose, and rasp its end smooth. Trim his triceps tendon to make a long flap, carry it across the end of the bone, and sew it to the fascia over the anterior muscles.
Release the tourniquet, control bleeding, drain and close the stump as usual (56.1).
DISARTICULATING THE ELBOW
Make equal anterior and posterior skin flaps. Start at the level of the patient's epicondyles and curve the posterior flap 2.5 cm distal to the tip of his olecranon. Bring the anterior flap just distal to the insertion of his biceps tendon. If necessary make any suitable flap.
Reflect the flaps to the level of his epicondyles. Start on the medial side. Find and divide the lacertus fibrosus. Free the origin of his flexor muscles from his medial epicondyle and reflect it distally to expose the neurovascular bundle on the medial side of his biceps tendon. Tie and cut his brachial artery just above the joint. Gently pull his median nerve and cut it proximally. Find his ulnar nerve in its groove behind his medial epicondyle and cut it proximally in the same way.
Free his biceps tendon from his radius, and his brachialis tendon from the coronoid process of his ulna. Find his radial nerve in the groove between brachialis and brachioradialis, pull it, and cut it proximally.
On the lateral side of his elbow, cut his extensor muscles 6.5 cm distal to the joint, and reflect their origin proximally.
Cut the patient's triceps tendon near the tip of his olecranon. Cut the capsule on the front of the joint, complete the disarticulation, and remove his forearm.
Leave the articular surface of his humerus intact. Reflect his triceps tendon anteriorly and sew it to the tendons of his brachialis and biceps.
Make a thin flap from his extensor muscles, reflect it medially and sew it to the remains of his flexor muscles on his medial epicondyle. Suture the muscle mass to cover the bony prominences and exposed tendons at the end of his humerus. Put sutures through the periosteum when necessary. Close the flaps without tension.
Release the tourniquet, control bleeding, drain and close the stump as usual (56.1).
56.5 Amputating through the lower arm and wrist
Losing a hand is a tragedy. Minimize it by trying to preserve as much of the length of a patient's forearm as you can. An elbow with even a short length of forearm is better than none. If possible, amputate through his metacarpus or wrist, rather than higher up. Ischaemia is an exception. The circulation in the distal forearm; like that of the distal lower leg, is not good. So if his arm is ischaemic, an amputation higher up his forearm may be better than one lower down.
If you have to amputate through his wrist, a plastic surgeon may later be able to make an `alligator mouth' out of his two forearm bones, so that he has something to grip with (Krukenberg's operation). Anteroposterior flaps are better than lateral ones, because the scar cannot retract between the bones.
AMPUTATING THROUGH THE FOREARM
For the general method see Section 56.1.
AMPUTATING THROUGH THE PROXIMAL FOREARM
Abduct the patient's arm on an arm board or side table, and place it supine. If you cut the flaps with his arm prone, they will later be twisted.
If there is enough good skin, make equal anterior and posterior flaps. If skin is scarce, make the best flaps you can.
Reflect the skin flaps with the deep fascia to the site of section. Tie, and cut his radial and ulnar arteries just above this site. Find his median, ulnar, and radial nerves, pull them gently, and cut them proximally. Cut his muscles transversely distal to the site of section, so that they retract above it. Trim away all excess muscle. Saw his radius and ulna and smooth their cut edges.
Release the tourniquet, control bleeding, drain and close the stump as usual.
Start elbow and shoulder movements as soon as possible.
AMPUTATING THROUGH THE DISTAL FOREARM
Start at the site of section and cut equal anterior and posterior flaps, as in Fig. 56-9. Make them as long as about one half the diameter of the forearm at the amputation site. Reflect the flaps proximally to the site of bone section.
Clamp, tie, and cut his radial and ulnar arteries just proximal to the site of section. Find his radial, ulnar, and median nerves, pull them gently and cut them high up so that they retract above the end of the stump. Saw both bones.
Release the tourniquet, control bleeding, drain and close his stump as usual (56.1).
DISARTICULATING THE WRIST
Make a long palmar and a short dorsal flap. Start the incision 1.5 cm distal to the patient's radial styloid, extend it distally
towards the base of his first metacarpal. Carry it distally across his palm, and then proximally to end 1.5 cm distal to his ulnar styloid. Make a short dorsal flap by joining the two ends of the palmar incision over the dorsum of his hand. Bring the dorsal flap distally level with the base of his middle metacarpal. If skin is scarce, vary the design of the flaps.
Reflect the flaps proximally with the underlying fascia to his wrist joint. Tie and cut his radial and ulnar arteries just proximal to the joint. Gently draw his median, ulnar, and radial nerves distally into the wound, and cut them short. Cut all tendons just above his wrist and let them to retract into his forearm. Cut round the capsule of his wrist joint and remove his hand.
Saw or nibble off his radial and ulnar styloids. Rasp the raw ends of the bones smooth and round.
CAUTION ! Don't injure his radioulnar joint or its triangular ligament. If you injure them, he will be unable to rotate his forearm, and the joint will be painful. Release the tourniquet, control bleeding, drain and close the stump as usual (56-1).
AMPUTATING THROUGH THE CARPUS
Make a short dorsal flap and a palmar one twice as long. Reflect the flaps proximally to the site of bone section, and expose the soft tissues under them.
Pull the flexor and extensor tendons, of his wrist distally, cut them, and allow them to retract into his forearm. Find the
four tendons which flex and extend his wrist (flexor and extensor carpi radial is and ulnaris), free their insertions, and reflect them proximally to the site of bone section.
Find his median and ulnar nerves and the fine filaments of his radial nerve. Pull them distally and cut them well proximal to the site of section. Tie and cut his radial and ulnar arteries proximal to the site of section.
Cut the remaining soft tissues down to bone. Saw across his carpal bones, and rasp all rough edges smooth. Anchor the tendons of his wrist flexors and extensors to his remaining carpal bones in line with their normal insertions.
Release the tourniquet, control bleeding, drain and close the stump as usual (56.1).
AMPUTATING THROUGH THE METACARPUS
Do this as for amputation through the carpus, but preserve what you can of the patient's metacarpals, and especially his thumb.
56.6 Amputating above the knee
Many above knee amputations for severe injuries could have been avoided, if only a below knee amputation had been done early enough, and not delayed. Provided the stump avoids the condyles of a patient's femur, the longer it is the better.
Be sure to exercise the stump immediately after the amputation, so as to strengthen: (1) the patient's remaining adductor muscles, and prevent the prosthesis moving outwards when he walks, and (2) his extensors, because they will have to extend both his hip and the prosthesis which is to form his knee. He will also have to learn to balance with his hip instead of his foot muscles.
Study the anatomy of his leg carefully, so that you can find his subsartorial canal fast, and tie his femoral artery. The canal and its vessels are described in Section 3.6.
AMPUTATING ABOVE THE KNEE
For the general method see Section 56.1. If the amputation is low enough, apply a tourniquet (3.8). Place a sandbag under the patient's buttock on the side to be operated on. Bandage his leg as far as his knee, so as to isolate it from the field of operation.
Prepare his thigh. Raise his leg so that you can prepare his upper thigh and groin. Put a drape behind it and another one in front.
Plan to leave 25 cm of his femur from the tip of his greater trochanter. If possible, make equal anterior and posterior flaps. If necessary, adapt them rather than amputating higher up. Start the anterior flap on the medial side of his thigh just proximal to the site of bone section. Curve it distally over the front of his thigh, to end on the lateral side opposite your starting point as in B, Fig. 56-11. Cut the posterior flap in a similar way. The combined length of the two flaps should be one and a half times the diameter of his thigh at the site of bone section.
Reflect the flaps to the site of section. Deepen the medial end of the anterior flap so as to expose his femoral artery underneath sartorius. Tie and divide his femoral artery and vein (3.6). Use two transfixion sutures for the artery. Begin the incision in his quadriceps along the line of the anterior flap, and bevel it proximally to the site of section, so as to make a muscle flap not more than 1.5 cm thick.
CAUTION ! If you are operating for arterial disease and the muscles do not seem viable (56.3), be prepared to amputate higher up.
Ask your assistant to raise the patient's leg while you cut across and bevel his posterior muscles distal to the site of section, in the same way as his anterior ones, so they retract to it. Trim away any excessively bulky muscle masses.
Find, clamp, and tie his profunda femoris artery on the posterior aspect of his femur adjacent to the linea aspera.
Find his sciatic nerve under his hamstring muscles, separate it from its bed without tension, pull it down, tie and cut it about 5 cm proximal to the end of his femur. Tie the artery that accompanies the sciatic nerve, but not the nerve itself.
CAUTION ! The collateral vessels which accompany his sciatic nerve can bleed profusely.
Cut the periosteum all round his femur and saw it across immediately distal to this cut. Rasp away the prominence of the linea aspera and smooth the end of the bone.
Slowly release the tourniquet, and tie bleeding vessels as they appear.
Sew the anterior muscle flap over the end of the bone. Sew its fascia to the posterior fascia of his thigh. Trim away any excess muscle or fascia. Insert drains deep to this flap.
Cover the stump with a crepe bandage and then apply a plaster cap. This will relieve pain, and its weight will help to prevent a flexion contracture developing.
CAUTION ! Don't let a flexion contracture develop.
PROSTHESES FOR AN ABOVE KNEE AMPUTATION
If the patient is a long time waiting for his prothesis, pad his stump well, make a cast round it and fit it into a sawn off thinned down crutch. Keep it in place with more plaster bandages. This will enable him to walk until his permanent prothesis is ready.
If you have to amputate both a patient's legs above his knees, consider the possibility of getting him short 'stumpy' protheses for both his legs. He may prefer them to a wheel chair, and they will be easier to balance with than prostheses of the standard length. He will however walk closer to the ground, and need two short sticks. 'Stumpy' prostheses are much easier to make, because they don't have jointed knees, and need only be sockets with simple boots on. Keep them in place with cords over his shoulder.
IF THERE IS A DANGER OF SEPSIS, USE DELAYED PRIMARY CLOSURE
56.7 Disarticulating the knee
Disarticulating the knee: (1) Is one of the easier amputations. (2) Preserves the distal femoral epiphysis of a child, and so allows his stump to grow. (3) Cuts little muscle and no bone, so it is quick, there is little bleeding, and infection is unlikely. (4) Allows the normal weight bearing end of the bone to bear weight in the prosthesis. Although long flaps are necessary to bring the scar posteriorly, there are such excellent anastomoses round the knee that they seldom become gangrenous, so it is a good amputation for ischaemic patients. If you have a choice, disarticulating the knee is better than amputating above it. Good prostheses are now available for disarticulated knees.
DISARTICULATING THE KNEE For the general method see Section 56.1.
ANAESTHESIA If possible, anaesthetize the patient, and then turn him onto his face, as in 'Primary Anaesthesia' Section 16.12.
METHOD Apply a tourniquet. Cut a long, broad anterior flap, and a shorter posterior one, as in A, Fig. 56-12. Mark these out with his knee flexed.
Start the anterior incision on the posteromedial side of his knee just proximal to the joint line. Extend it 10 cm below his tibial plateau, and then curve it proximally to end at a point
just proximal to the joint line on the posterolateral side of his knee.
Start the posterior incision at the origin of the anterior one. Extend it 5 cm distal to the popliteal flexor crease. Then curve it proximally to meet the anterior incision.
CAUTION ! The anterior flap must have an adequate blood supply. If it might not, cut two equal medial and lateral flaps beginning just above the insertion of the patellar tendon.
Dissect the deep structures on the medial side of the patient's knee. Expose the tendons of his medial hamstrings and cut them as far distally as you can.
Find, tie and cut the main trunk of his popliteal artery just distal to its superior genicular branches. These arise high in the popliteal fossa. Tie his popliteal vein. Reflect the posterior flap, cut the fascia, and dissect downwards in the midline between his medial hamstrings on one side and his lateral ones on the other.
Cut the deep fascia along the border of the anterior skin flap. Cut his patellar tendon as close to its insertion into his tibia as you can. Reflect his skin, his fascia, his patellar tendon, and the synovial membranes as a single flap (B).
On the lateral aspect of his knee, expose and divide his biceps tendon and his iliotibial tract.
Find his common peroneal nerve below his biceps tendon, as it goes towards the head of his fibula. Cut it proximally so it retracts above the level of the amputation.
Reflect the short posterior flap and cut his collateral and cruciate ligaments near their attachments to his femur (C). Find his tibial nerve, draw it gently into the wound, and cut it proximally (D).
Dissect the posterior joint capsule from his tibia. Strip the heads of his gastrocnemius from his femur, and remove his leg.
CAUTION ! (1) The popliteal vessels lie very close to the posterior surface of the knee joint. If you have already tied them high up, they should not be in danger. (2) There is no need to disturb the articular cartilage of his femur, or to remove his patella.
Draw his patellar tendon posteriorly through the intercondylar notch of his femur, and sew it to the ends of his hamstring tendons with several interrupted sutures (E).
Stitch his sartorius and his iliotibial tract to the fascial part of his extensor mechanism. Remove the medial and lateral tubercles of the lower end of his femur. Remove the tourni quet, control bleeding, drain and close the stump as usual.
Prepare to fit a permanent prosthesis in 6 to 8 weeks.
56.8 Amputating below the knee
This is the most common amputation. If a patient has a good prothesis, he can do almost anything with it. The method described below, that of Perssen, as modified by Anderssen, uses two short equal medial and lateral flaps, and is especially suitable for leprosy and ischaemia. You can use it, for all purposes, except when a guillotine incision would be wiser (56.2).
The best length of stump for a modern prosthesis is 12 to 18 cm below the patient's tibial tuberosity. If he is to have the traditional type of peg leg he needs a shorter 10 cm stump. A stump of only 5 cm too easily slips out of a prothesis, so that he will be better with an amputation higher up. Don't amputate below the muscle area of his calf, because the tissue here has a poor blood supply.
AMPUTATING BELOW THE KNEE For the general method, see Section 56.1.
ANAESTHESIA It is a great help to be able to turn the patient onto his face, so a low subarachnoid anaesthetic (A 7.6) is suitable. If you cannot anaesthetize him lying on his face, bend his knee over the end of the table.
PREPARATION Wash, shave, and paint the operation site. Apply a tourniquet. As soon as he is anaesthetized, raise his leg steeply for a few minutes to drain the blood from it. Then bow up the tourniquet. Wrap his foot securely in a sterile towel.
Mark out the flaps.
Line 'A' is the site of bone section 8 to 14 cm distal to his tibial tubercle, 12 cm is optimal. This is about the length of your index finger, with the base of your second metacarpal on his tibial tubercle.
Line 'B' is 2 cm distal to 'A', and marks the point where the flaps divide anteriorly.
Line 'C' marks the distal extent of the flaps.
If you are not certain of the geometry of the flaps, cut them too long rather than too short.
Cut through the patient's skin, his subcutaneous tissue, and his deep fascia. Cut through the periosteum on the anterior surface of his tibia.
Raise two medial and lateral semicircular flaps to include the skin, subcutaneous tissue, deep fascia and the periosteum on the front of his tibia. Reflect them proximally for 2 cm only.
Divide the underlying muscle at this level, and tie the major vessels as you meet them.
Cut an oblique notch in the front of the tibia, then saw through it at line 'A: The notch will be easier to make, if you saw it before you saw through the tibia.
Saw through the fibula obliquely 1 to 3 cm higher up.
Raise his leg, remove the tourniquet, find and tie the remaining vessels. Suture the fascia with interrupted monofilament sutures.
Don't try to suture the muscles. They are still attached to the deep fascia, and should fall neatly into place under the sutured layer of deep fascia.
CAUTION ! If there are any of the indications for delayed primary suture, as listed Section 56.1, this would probably be wiser. Otherwise, close his skin with interrupted monofilament sutures. Leave any dog ears.
If you have done a neat job, there should be no dead spaces in which a haematoma can collect. If you are not confident that you have eliminated any dead spaces, insert a drain.
Cover the stump, including the patient's knee, with generous gauze pads, and apply a firm pressure dressing. Mould a thin plaster shell round the stump, including the distal part of his thigh, with his knee fully extended, or apply a backslab. This is an effective way of preventing a flexion contracture.
Day 3. Keep the stump elevated. Start quadriceps exercises.
Day 14. Remove the plaster shell and the sutures. Bind the stump with a tight bandage. Start' active knee exercises against resistance.
Day 28. Fit him with his first prosthesis.
CAUTION ! Watch for and prevent a flexion contracture, because it will prevent a prosthesis being fitted. If you are too late to prevent it, the best treatment may be to cut the stump even shorter, to allow the contacture to become even more severe, and then to fit a peg leg.
56.9 Syme's amputation
This is a disarticulation of a patient's ankle, adapted so that the stump can bear his weight. All the bones of his foot are removed, and his malleoli are sawn off, so that the end of his tibia is flat. A large full thickness heel flap is removed subperiosteally from his calcaneus, and brought forward to make a solid covering for the end of his tibia. He can walk about his house on it without a prosthesis or crutches, even though his leg is about 5 cm short. He can also wear a simple and durable elephant boot. His distal tibial epiphysis is preserved, so it is good amputation if he is a child.
This is an excellent amputation if it is well done, but it is also the most difficult of the amputations described here. If you
are not skilled, amputating below his knee would be wiser. However, if a Syme's amputation fails, a below knee amputation is always possible.
A patient's posterior tibial vessels run into his foot just behind his medial malleolus. If you cut them too high, they cannot supply his heel flap. So: (1) Shell out his calcaneus from under the periosteum when you dissect the flap. If you can preserve the periosteum a useful piece of new bone will form in it. (2) Cut the vessels as far distally as you can. (3) Be sure to keep the heel flap correctly aligned postoperatively, so that the patient can walk on it.
SYME'S AMPUTATION
INDICATIONS Lesions confined to the forefoot only, when the operator is fairly skilled.
CONTRAINDICATIONS (1) Arterial disease, unless this is strictly confined to the distal part of the foot. One and preferably both ankle pulses should be present. (2) The need for an elegant prosthesis. A woman is likely to prefer a below knee amputation. (3) Infection. Syme's amputation has a special posterior flap and is not suitable for delayed primary closure. (4) A very inexperienced operator. (5) This is not a good amputation for leprosy.
METHOD For the general method, see Section 56.1. Apply a tourniquet to the patient's thigh (3.8), and let his ankle hang over the end of the table. Stand at the end of it facing his foot.
Mark out the flaps with methylene blue. Hold his ankle at 90°. Start the incision at the distal tip of his lateral malleolus. Bring it over the front of his ankle, level with the distal end of his tibia to a point one finger's breadth inferior to the tip of his medial malleolus. Then, bring the incision under the sole of his foot to the tip of his medial malleobus. Cut all structures down to the bone.
Forcibly plantar flex his foot and cut all anterior structures down to the bone. Put a knife into his ankle joint between his medial malleolus and his talus and cut his deltoid ligament. Do the same on the lateral side and cut his calcaneofibular ligaments.
Put a bone hook posteriorly in his talus to plantar flex his foot even more.
Using a new, sharp scalpel blade, dissect the tissues away from the medial and lateral sides of his talus and calcaneus, keeping as close to the bone as you can, f possible within the periosteum. Then cut his calcaneus out of his heel. Work at it from all sides keeping very close to the bones. When you get tired of one approach, start from another. This is the most difficult and the most critical part of the operation.
Pull his talus and calcaneus forward with a bone hook. Dissect posteriorly, and cut the posterior capsule of his ankle and his Achilles tendon. Then dissect subperiosteally round the ball of his heel, so as to free his calcaneus and reach the first incision on his sole. As you do so, steadily dislocate his foot downwards more and more, until you reach the distal end of the plantar skin flap and finally free it from his ankle.
CAUTION ! (1) Keep within the periosteum very close to the bone: as you dissect his calcaneus out of his heel flap, or you will cut his posterior tibial and peroneal arteries which are very close to the back of the joint capsule. If necessary, remove his calcaneus piece by piece. (2) Don't trim away any muscle or fat in the heel pad, because he needs it to walk on. (3) Keep close to the bone, and don't button hole the heel flap.
Remove his whole foot except for the heel flap.
Dissect the heel flap from his malleoli, and reflect it posteriorly. Saw off his malleoli and the articular cartilage of his tibia in a single cut. Make sure that the ends of his tibia and fibula are accurately horizontal, so that he can bear weight squarely on the stump.
CAUTION ! (1) The cut surfaces of his bones must parallel to the ground when he stands. (2) If you are amputating in a child, don't destroy his distal tibial epiphysis.
Round and smooth all the sharp corners of his tibia and fibula. Cut his medial and lateral plantar nerves proximally.
Pull on any tendons you can see, cut them and let them retract proximally into his leg.
Tie and cut his posterior tibial artery and vein just proximal to the cut distal edge of the heel flap. Tie his anterior tibial artery in the anterior flap.
Using a step incision cut his Achilles tendon about 10 cm proximal to the heel flap. This will prevent the heel stump displacing. If you don't do this, his Achilles tendon is apt to pull up the back of the stump. Cut it high up, or you may injure his posterior tibial vessels.
Release the tourniquet, and control bleeding. Bring his heel flap forward to cover the ends of the bones.
CAUTION ! (1) Don't remove the dog ears, however big. They carry an important share of the flap's blood supply and will disappear later. (2) Prevent the heel pad from tilting out of alignment with the patient's tibia-this is a real disaster! Apply two long U-shaped strips of strapping as in C, Fig. 56-14. Put the first piece on starting below his knee posteriorly, bring it round the flap, and then anteriorly, so as to flex the flap over the stump. Apply the second strip from one side to the other. Keep these strips in place for at least three weeks, and replace them as necessary.
POSTOPERATIVE CARE FOR A SYME'S S AMPUTATION
Check the strapping daily, to make sure that the patient's heel pad is centred over his tibia. Adjust it if necessary.
At 2 weeks reapply the strapping, and put on a well moulded cast round the stump. He should not bear weight yet.
At 6 weeks take the mould for the prosthesis. By now the stump has usually stuck firmly enough to the tibia to bear weight inside a cast, so apply a new one and let him bear weight on it.
At 10 to 12 weeks he is ready for his definitive prosthesis, either an elephant boot, or a more sophisticated one.
56.10 Amputating through the foot and toes
This is one of the less useful amputations, its main use is in crush injuries of a patient's toes. Its advantage is that if he fills the front of his shoe with cotton wool, he can walk reasonably well without a prosthesis. Try to preserve as much of his metatarsals as you can. If you cannot preserve them, do a Syme's amputation, or amputate below his knee. If necessary, you can amputate as far back as their bases. Don't try to amputate through his tarsus, because the stump will tilt. If you can preserve his dorsiflexors, he will have a reasonable stump, if you lose them, his foot may go into plantar flexion.
Amputating through the metatarsals is sometimes indicated in leprosy with very distal ulcers under the heads of the metatarsals. It is a poor amputation for arterial gangrene, which usually needs an amputation below the knee, or even above it.
Amputate toes in the same way as the fingers (75.24). Preserve a patient's big toe, if you can, because it has considerable functional value, particularly in the 'take off' of normal walking. Its most important part is the head of the first metatarsal, so preserve this if you can, even if it does mean cobbling up the remains of an injured foot. The distal phalanx of the big toe matters much less.
Amputating a patient's second toe soon causes severe hallux valgus, but amputating his third, fourth and fifth will cause him little disability.
AMPUTATING THROUGH THE FOOT AND TOES
METATARSAL AMPUTATION
INDICATIONS (1) Crush injuries of the patient's toes. (2) Occasionally, in leprosy when there are large and persistent ulcers due to osteitis. (3) Gross infections presenting late with osteitis.
CONTRAINDICATIONS The risk of failure is considerable if his toes are gangrenous, particularly if he is diabetic.
METHODS For the general method see Section 56.1. Make a long plantar and a short dorsal flap, as in Fig. 56-15. This will bring the suture line dorsally.
Start the dorsal incision at the site of bone section on the anteromedial aspect of the patient's foot. Curve it distally a little to reach the midpoint of the lateral side of his foot. Take the plantar incision distally beyond his metatarsal heads 1 cm proximal to the crease of his toes. The foot is thicker medially, so make the flap slightly longer on the medial than on the lateral side.
Cut the plantar flap to include his subcutaneous fat and a thin bevelled layer of his plantar muscles. Reflect the plantar flap proximally to the site of bone section and then use large bone cutters to divide his metatarsals. Find the nerves and cut them well proximally. Pull the tendons and cut them so that they retract into the stump of his foot.
Release the tourniquet, control bleeding, drain and close the stump as usual (56.1).
AMPUTATING AT THE BASE OF A PROXIMAL PHALANX
The big toe: Make a long posteromedial flap. Start the incision at the base of the patient's big toe in the midline dorsally. Curve it distally over the medial side of his toe for a
distance slightly greater than its dorsoplantar diameter. Then bring it proximally across the plantar surface. Section his flexor and extensor tendons and suture them together over the end of the bone to maintain the position of the sesamoids under the head of his first metatarsal.
Alternatively, some surgeons make a `V' or a `Y' on the medial side of the foot.
Second toe Avoid amputating this.
The remaining toes Make a short dorsal racquet incision, proceed as in the corresponding amputation in the hand.
PLAN FLAPS LONG, YOU CAN ALWAYS SHORTEN THEM LATER
