The Basics of Amputation Surgery

Amputation involves the loss of one of the four extremities at various levels. This can greatly interfere with functioning and quality of life. The person who sustains an amputation often feels like less of a person because they do not have full capabilities of all their limbs. Amputations involve the loss of skin, other connective tissues, muscle and bones in the affected extremity. The surgeon doing an amputation procedure for whatever cause must recognize that these different body parts heal at different rates and that it is only when all areas have healed that an amputee begins to work with a prosthetic device.

There are two types of amputation surgery. They include:

• Getting rid of whatever crushed or diseased tissue that will not be able to heal and be salvaged. This perhaps the easiest part of the surgeon’s job, with the hardest part related to identifying exactly how much needs to be removed for the viability and survival of the stump.
• Reconstruction surgery.   This type of surgery occurs after the initial amputation has been performed and is designed to put the extremity in the best possible way to receive a prosthesis.

A successful amputation surgeon knows how to carefully balance the loss of nonviable tissue with the gain of a prosthesis. The surgeon must also be prepared to work as one part of a team of internal medicine doctors, physical therapy specialists, occupational therapy,  psychiatry, and prosthetists. It takes all these people working together to properly help the amputee. There is a big difference between upper extremity and lower extremity function. The upper extremities are not load-bearing, so the effort is put into devising a prosthetic device that can mimic small motor skills lost when the patient sustained the amputation. Lower extremities, on the other hand, are load-bearing so the focus will naturally shift to prosthetics that can withstand the rigors of standing and walking.

One of the golden rules in amputation care is to remove only that tissue that is diseased and just keeping that tissue which is the most likely to heal without difficulty. In past years, it was more difficult to separate the foot at the level of the ankle or to separate the knee at the level of the knee joint; however, recent prosthetic techniques have been developed which allow for these kinds of amputations. Sometimes the surgeon makes an error and fails to cut off enough of the diseased tissue so that another amputation further up is required. When planning an amputation level, it is important to choose a level that will yield the best ability for the remainder of the limb to function along with a prosthesis.

The surgeon must do an amputation that involves the salvage of skin to cover the amputated area. This usually yields a scar that is better able to handle the prosthetic device because it is non-tender when it heals. The doctor must choose the right area to have the scar so that the area can heal well and work with a prosthetic device. Fasciocutaneous flaps are flaps of muscle, connective tissue, and skin that can be harvested from nearby tissue to cover the exposed bone. A Fasciocutaneous flap can be brought down and can cover the bony prominence, providing padding for the bony prominence left over after the limb has been amputated.

Sometimes skin grafts are necessary to cover the open areas left by the amputation. These grafts cannot be directly covering bone but should be laid down over areas where the muscle can cushion the space between the skin graft and the bone. The skin grafts heal better when they are cushioned.  It takes time for the skin grafted area to accept a prosthesis because they heal more slowly than, say, a fasciocutaneous flap.  Over a period of months, however, even skin grafted areas at the end of a stump can be toughened up so that it can handle the prosthetic device without breaking down the tissue. There are long-term situations regarding the skin. Besides the breaking down of the skin, there can be callus formation, wart-like growths on the stump and skin rashes which are best handled on the advice of a dermatologist who understands how skin heals after an amputation.

An ideal amputation includes leaving behind muscle that can cover the bony end of the amputation. These provide for strong padding and less pain when dealing with the prosthesis. The muscle must be attached to something at the end of the limb so that, when activated, the muscle has some force upon which to act and can regain its strength. If the muscle is not attached to a firm object, such as a tendon or bone, it will simply waste away, leaving a thin and nonfunctioning muscle. There are several types of muscle stabilization:

• Myofascial closure. The outer fascial layer of the muscle is attached to deeper muscle, providing a covering over the bone. It really only stabilizes the surface muscles and does not allow for a good functioning of the involved muscle. It is best used for people who have poor circulation or poor healing.
• Myoplasty. The muscles on one side of the amputation are attached to muscles on the other side of the amputated limb so that the muscles can benefit from the push-pull of opposing muscles as well as providing good cushioning for the bone. Unfortunately, myoplasty alone may cause the sliding back and forth of muscle tissue across the end of the bone and can be very painful.
• Myodesis. This involves attaching the muscle and available tendons to the bone itself at the end of the stump. The deeper muscles of the stump have usually handled this way while the superficial muscle groups are attached to opposing muscles overlying the deeper ones.
• Tenodesis. This is the preferred method of attaching bone to muscle.  It salvages the tendon of the muscle and directly attaches the tendon to the bone. This is the way it is normally done in nature, and best allows for the functioning of the muscle.

The trick to attaching muscle properly is to make sure it is not done under a great deal of tension applied to the muscle. It is best to err on the side of letting the muscle be too lax than it is to have the muscle much too tight, which can lead to contracture of the muscle.

The major blood vessels must be tied off and cut at the most distal part allowable for proper healing.  The smaller blood vessels should remain intact with their supply, which is the superficial muscles, tendons, and skin. There must be adequate blood supply to the stump so it can heal properly. Doctors often put in drains at the time of surgery to soak up blood before the blood vessels completely close off and to prevent blood clots from forming at the end of the stump.  Eventually, the drains can be removed.

Bone cannot simply be cut off from the end of the stump. To minimize pain, the bone must be smoothly rounded off without irregularities or sharp edges. If the amputation is done by disarticulating the joint at the end of a bone, sometimes the part of the bone that is to be made into the stump must be made narrower so that there isn’t a bulbous end to the bone. The end of the bone should be covered with periosteal tissue. If this is not possible, the raw ends of the bone will form a smooth callus, which may be satisfactory if there is no periosteal tissue left over to form a bony cap over the end of the stump. Some amputations must be done in stages. This means that the worst of the distal infection and gangrenous material is cut off first with better chances for healing.  In the second or subsequent phases, more bone and tissue is removed, shortening the stump but allowing for better healing of the tissues. When a leg is injured, there is often an area where the doctor cannot tell exactly whether or not the remaining tissue will heal. He must wait to see if there is additional dead and damaged tissue to be removed at a later date.

Revisions involve the subsequent surgical procedures that must be done if the initial amputation does not heal correctly or if there are painful aspects to the first amputation once it has healed.  The same principals in place for a primary amputation are used during revision surgery. After the surgery, the surgeon must manage issues such as postoperative infection, the formation of blood clots and poor healing of the tissue.  In such cases, revisions may be necessary so that the skin properly heals.

The end of the extremity must be covered with a soft, yet compressive dressing that minimizes the degree of swelling at the site of the surgery. Drains are placed to allow serious and bloody liquid to drain out in the days following the amputation. The dressings must be sterile so that the wound is less exposed to bacteria that can lead to infection. Some doctors use a more rigid dressing that allows for faster placement of a prosthesis. Good post-operative care of the amputated limb involves resting the extremity as it heals, using dressings to prevent infection and changing the dressings infrequently as long as they remain dry. Rigid dressings are a lot like casts and can be made from several different types of materials. They should be changed so the wound can be inspected after 5-14 days. 

Sometimes a prosthesis is put on right at the time of surgery. This allows for better post-operative functioning of the prosthesis and reduces the psychological impact on the patient who is dealing with the loss of an extremity.  Because of issues of swelling and maturing of the scar, the prosthesis worn by the person right after surgery may need to be modified for up to a year after the initial amputation. Technologically-advanced prostheses are the ideal endpoint of amputee care; however, more simple prosthetics work the best in the initial year, when the tissue is going through the healing process. In the video below, Dr. Terrence Sheehan explains what amputees can expect during the first six months of post-surgery.