June 20, 2024

Amputation is the surgical removal of a limb or part of the limb through a bone or multiple bones. It is the removal of all or part of a limb or extremity such as an arm, leg, foot, hand, toe, or finger.

See also: Limb Salvage Surgery: Principles

Amputation

Definition

Amputation

Surgical removal of limb or part of the limb through a bone or multiple bones

Disarticulation

Surgical removal of hole limb or part of the limb through a joint

Indications

Indications

  1. Peripheral vascular disease with/without diabetes (the most common cause of amputations in age between 50-75). Approx. half are patients with diabetes.

2. Trauma: most common cause in young

Blood supply of limb irreparably damaged

Limb severely damage

Indications

3. Burns or electrical injury

4.Frostbites

5. Infection: acute or chronic infection, if not amenable to medical or surgical treatment. Fulminating gas gangrenes

Indications

6. Malignant  tumours

7. Nerve injuries: trophic ulcers in anaesthetic limbs

8. Congenital anomalies: e.g. tibial and fibular hemimelia

Metabolic cost of Amputee Gait

“The energy required for walking is inversely proportionate to the length of the remaining limb and number of functional joints preserved”.

The higher the level of lower-limb amputation, the greater the energy expenditure that is required for walking

As the level of the amputation moves proximally, the walking speed of the individual decreases, and the oxygen consumption increases

In transtibial amputations, the energy cost for walking is not much greater than that required for persons who have not undergone amputations.

For those who have undergone transfemoral amputations, the energy required is 50-65% greater than that required for those who have not undergone amputations.

Load Transfer:

Indirect load transfer:

Occurs in transosseous amputation through long bone occurs in transfemoral and transtibial

(the end of the stump does not take all the weight and the load is transferred all the weight by contact method  so an intimate fit of the prosthesis is necessary)

Direct load transfer:

Terminal weight bearing occurs in Knee and ankle disarticulations

(intimacy of prosthetic socket is necessary only for suspension)

Amputation Wound Healing

Depends upon several factors including nutrition, adequate immune status, and vascular supply.

TcPO2 ( Transcutaneous partial pressure of oxygen) is the factor most predictive of successful wound healing.

Nutrition and immune status:

Malnourished:

Albumin < 3.5 g/dl

Absolute lymphocyte count < 1500/mm3

Vascular Supply:

Haemoglobin > 10 g/dl

Absolute Doppler pressure < 70 mm Hg was described as a minimum inflow pressure to support wound healing.

Ischemic Index: 0.5

ABPI >0.45 suggest adequate blood flow

Trans cutaneous partial pressure of oxygen

>40 mm Hg (Ideally 45 mm Hg) are correlated with an acceptable uneventful wound healing rate

<20 mm Hg are predictive of poor wound healing

Surgical principles

  1. Tourniquet desirable except in ischaemic limbs

2. Level of amputation

Traditionally the levels of amputation are:

Transfemoral:10-12 cm from the knee joint and at least 18 cm from the tip of greater trochanter

Transtibial:14-17 cm from knee joint

Transradial: 18 cm from elbow

Transhumeral: 20 cm from shoulder joint

Level of amputation

Surgical principles

3. Skin and flaps

Generally equal anteroposterior flaps

For transtibial amputation for an ischaemic limb, a long posterior flap used

4. Muscles

Myoplasty: muscles divided distal to the level of the intended bone section and sutured to the opposing group of muscles and fascia.

Myodesis: the opposing group of muscles are sutured to each other through drill holes in the bone ends and periosteum.

Surgical principles

5. Nerves

6. Blood vessels

7. Bone

Excessive periosteal stripping avoided

Bony prominences resected and rasped to form a smooth contour.

Bevelling is done where required

8. Drain: haemostasis maintained before closure and drain removed after 48-72 hours

Complications

  1. Haematoma

2. Infection

3. Wound necrosis

4. Contractures of joints

5. Neuromas

6. Phantom sensation/phantom limb pain