Orthopaedics and trauma
amputations
INTRODUCTION
Appraise
1. The main indications for amputation are:
Vascular disease—arterial or venous
Diabetes (diabetes and vascular disease together account for about 85% of amputations)
Infection (now only responsible for 1.5% of amputations)
Neurological causes such as nerve injury and its secondary effects
2. Major upper limb amputations are rarely required (only 3% of the total).
GENERAL PRINCIPLES
Appraise
1. If you are in any doubt about the necessity for amputation, obtain a second opinion from a senior colleague.
KEY POINTS
Anticipate
2. Operate using general anaesthesia whenever possible.
3. The level of amputation and type of prosthesis are influenced by:
4. Energy conservation is an important consideration when planning lower-limb amputation and the chosen level is crucial. Energy expenditure following bilateral below-knee amputation is still less than that of a unilateral above-knee amputation. Plan to preserve every possible dynamic structure, including the knee joint and the epiphysis in children.
5. Appraise the blood supply of the limb clinically by looking for skin colour changes, shiny atrophic appearance and lack of hair growth. Feel for skin temperature changes. Be willing to order transcutaneous Doppler recordings and measurement of the ankle-brachial index, thermography, radioactive xenon clearance and transcutaneous PO2 measurements.
6. Assess the bone by taking plain radiographs in two planes, tomograms or a radioisotope bone scan. In the presence of bone or soft-tissue malignancy, ensure that the diagnosis has been confirmed with a biopsy. Computed tomography (CT) and magnetic resonance imaging (MRI) are essential in fully staging the lesion and assessing the necessity for amputation. Limb-sparing surgery has recently become more feasible, provided the correct indications are followed under guidance from expert tumour surgeons.
Prepare
1. As the surgeon performing the operation it is your personal responsibility to obtain consent and explain possible complications. Fully inform the patient of the proposed operation. Obtain consent to amputate, if necessary, more proximally than you intend.
2. Give prophylactic antibiotics: penicillin (or erythromycin) plus one other broad-spectrum antibiotic. Swab and culture any wounds preoperatively.
3. Clean the limb and seal off the infected or necrotic areas.
4. Arrange for the disposal of the limb after amputation to the pathology department or straight to the incinerator.
Action
General techniques
1. Use a tourniquet except in peripheral vascular disease. Exsanguinate the limb by elevation for 2–4 minutes rather than using an Esmarch bandage.
2. Prepare the skin and apply the drapes.
KEY POINTS
Skin flaps
Mark the proposed skin flaps preoperatively.
They should be approximately as long as the base is wide at the level of bone section.
Leave them too long rather than too short.
If amputation follows traumatic injury, preserve all viable skin to create an adequate stump.
In the presence of vascular disease do not undermine the edges of the flaps.
3. Wherever possible, include underlying muscles in the flap (myoplastic flap) since this greatly improves the skin blood supply and covers and protects the stump. Muscles provide power, stabilization and proprioception to the stump. In emergency cases remove all dead muscle (this avoids gas gangrene) and leave viable muscle (red, bleeding and contracting). In elective cases cut the muscle with a raked incision angled towards the level of bone section.
4. Double-ligate major vessels with strong silk or linen thread. Ligate other vessels with absorbable material such as polyglycolic acid (Dexon).
5. Gently pull down nerves, divide them cleanly and allow them to retract into soft tissue envelopes. Ligate major nerves with a fine suture prior to and just above the site of division. This stops bleeding from accompanying vessels and decreases neuroma formation.
6. Prepare to cut the bone at the appropriate level. Remember that the stump must be long enough to gain secure attachment to the prosthesis and to act as a useful lever but short enough to accommodate the prosthesis and its hinge or joint mechanism. Divide the periosteum and cut the bone with a Gigli or power saw. During bone section, cover the soft tissues with a moist pack and irrigate afterwards to remove bone dust and particles from the soft tissues. Round-off sharp bone edges with a rasp.
7. Check that the flaps will approximate easily.
8. Release the tourniquet and secure haemostasis.
10. Suture the flaps together without tension, starting with the muscle. Handle the skin carefully and close it with staples if available, or interrupted nylon sutures.
11. In the presence of infection or if you have any doubt about the viability of the flaps, approximate the muscles loosely over gauze soaked in saline or proflavine to prevent them from contracting. Do not close the skin. Plan delayed primary closure at 5–7 days.
Aftercare
1. Apply a well-padded compressible but not crushing dressing, using either cotton wool or latex foam. Hold this in place with crepe bandage taking care to avoid fixed flexion or other deformity of neighbouring joints.
2. Except in cases with infection or doubtful flap viability, apply a light shell, maximum four layers, of plaster of Paris over the dressing. This makes the patient more comfortable and able to be more mobile in bed. In specialist centres a prosthetist can apply a rigid dressing to which a temporary pylon can be attached, allowing early ambulation.
3. Leave the dressing undisturbed if possible for 10 days.
4. Order regular physiotherapy to prevent joint contractures.
5. Encourage mobilization and use of the stump as soon as the patient is comfortable.
6. When the wound has healed and sutures have been removed, apply regular stump bandaging to maintain the shape of the stump.
7. As soon as possible refer the patient to the local limb-fitting centre if you had not already done so before operation.
Special situations
Amputations in children
Children’s amputations present their own special problems:
Growing bones at the site of amputation will overgrow by apposition, not related to growth at the proximal growth plate. You may need to revise the bone to prevent skin problems.
If possible, always preserve epiphyseal growth plates.
Amputations of accessory digits in children:
Certain cultures discriminate against children with accessory toes of fingers while other cultures applaud them. Sensitivity is needed and the wishes of the child and parents must be respected.
Accessory digits, and if necessary the associated metacarpals or metacarpals, should be amputated according to the principles described below.
Amputations of lower limbs with congenital tibial and fibular dysplasia in children:
Congential tibial and fibular dysplasia is frequently bilateral and presents with shortened lower limbs and a child who is crawling on the ground.
The whole tibia may be missing, in which case the child is weight bearing through the distal femur.
Discuss the possibility of making a prosthesis immediately and during subsequent growth.
Discuss amputation with the parents.
Use the principles of lower limb amputation discussed below.
Decision making for amputations in major trauma
1. Objective criteria help predict amputation following lower extremity trauma. The Mangled Extremity Score (MESS) is one such system. It uses four significant criteria of skeletal/soft-tissue injury, limb ischaemia, shock and patient age.
2. Such systems help you to discriminate between salvageable limbs and those better managed by primary amputation.
Complications
Haematoma
1. Haematoma in the stump predisposes to infection and greatly delays prosthetic fitting.
2. Drain collections of blood by aspiration or a small incision. Perform this in the operating theatre under sterile conditions, not on the ward. Local anaesthesia is usually sufficient.
3. If there is clearly uncontrolled haemorrhage, apply firm compression and elevate the limb while you make arrangements to explore the stump under a general anaesthetic.
Infection
1. Amputation stumps are more at risk of infection than most other surgical wounds. The stump tissues are often poorly vascularized, there are often infected lesions in the distal extremity, and patients are often frail and elderly, with poor resistance to infection.
2. Give prophylactic antibiotics to all lower-limb amputees. Choose antibiotics that are active against Clostridia, Escherichia coli and staphylococci.
3. Handle all soft tissues with care and avoid leaving dead muscle and long sections of denuded cortical bone in the stump.
4. Treat wound infections promptly with antibiotics. Incise and drain any collection of pus.
5. If a chronic sinus fails to dry up with a course of antibiotics lasting up to 6 weeks, explore the stump under general anaesthesia. You will usually find a focus of infection such as a small bony sequestrum or a lump of infected suture material.
Flap necrosis
1. Prevent this complication by carefully assessing skin viability prior to amputation and by handling all skin edges and flaps with the utmost care. Use a myoplastic flap wherever possible as this always has a better blood supply.
2. Treat small areas of wound necrosis conservatively. The wound often granulates beneath the patch of blackened, sloughing skin, which eventually separates spontaneously.
3. Major flap necrosis requires either a wedge resection, down to and including bone, or re-amputation to a higher level.
Joint contractures
1. Treat or prevent mild contractures by early active and passive exercises, place the joints in a corrective posture, fit a prosthesis that retains the position, and encourage mobilization. For example, regularly lying the patient prone discourages hip contractures.
2. Severe contractures may require serial plasters or surgical release; otherwise, applying a prosthesis is likely to be impossible and useless.
