What is a limb amputation surgery?

Limb amputation surgery involves the removal of most or all of either a front or hind limb. The front limb may be amputated at the mid-humerus (upper arm) level, at the level of the shoulder joint, or at the level of the shoulder blade (including removal of the scapula). The hind limb may be amputated at the mid-femoral (thigh) level, at the hip joint, or at the level of the pelvis (including removal of part of the pelvis). The optimal level to perform a limb amputation depends on the underlying condition necessitating the amputation. 

Prior to undergoing a limb amputation, the patient is placed under general anesthesia, and the affected limb is clipped and cleansed with a surgical antiseptic. A nerve block or epidural is performed to reduce the amount of general anesthetic required and to ensure the patient is comfortable as they wake up. Once the patient is ready, the surgeon first makes a skin incision around the limb at the appropriate level. Muscles and tendons are carefully transected, and veins and arteries are identified and ligated to prevent blood loss prior to transection. Depending on the level of the amputation, the bone is cut with a saw or the joint capsule and associated ligaments are transected to separate the two bones. The transected ends of the muscles are attached to one another, covering the end of the bone or joint. The subcutaneous tissue and skin are then sutured closed over the site. In some cases, a surgical drain may be placed prior to closing the incision. This will typically be removed within a few days. 

When is a limb amputation surgery indicated?

A number of different injuries or illnesses may necessitate a limb amputation. These fall into two major categories: trauma and tumors. Any major limb trauma for which a functional outcome is deemed very unlikely or impossible is a candidate for an amputation. Examples of this include non-reconstructible joint fractures and irreversible nerve damage (such as the severing of an essential nerve.) 

Tumors (neoplasms) are abnormal proliferations of cells which can be either benign or malignant (cancerous). Some tumors can be removed from a limb without affecting limb function; these are usually small and involve only the skin and/or underlying soft tissues or the bone of a toe. Sometimes a benign tumor that is too large to remove can be left in place as long as it is not affecting limb use. Even though a benign tumor does not have the risk of spreading to other parts of the body, it can eventually interfere with comfort and/or limb function; in these cases, amputation can restore a patient’s comfort, and can actually improve their mobility by removing the weight of the non-functional limb. A malignant (cancerous) tumor of a limb may originate within bone, joint tissues, or soft tissues such as muscle, connective tissue, and skin. These tumors must be treated aggressively, as they often spread to other parts of the body, where they can cause terminal organ dysfunction. Wider surgical margins are required to remove these tumors, and often in order to achieve wide enough margins, removal of the limb is necessary. 

What is the post-operative recovery for a limb amputation?

Following a limb amputation, most patients remain hospitalized for 24-48 hours to provide injectable pain medication until they resume eating and to ensure they are comfortable on oral pain medications before going home. Most patients will not go home with a bandage over their surgical incision, although if a surgical drain is present, this will typically be covered by a light dressing. If a drain is present, you will be instructed on any necessary drain care and a time will be scheduled within the next few days to bring the patient in for drain removal, which is a quick procedure that does not require anesthesia. 

During the immediate post-operative period, you will be instructed on how to support your pet with a sling or towel as they learn to ambulate on three legs. Most patients undergoing an amputation have not been using their limb for some period of time, and are already fairly accustomed to walking on three legs; in fact, many patients appear to get around easier within several days of surgery than they did before, most likely because they no longer have to contend with the weight of the unused limb. You will also be given pain medications to ensure your pet remains comfortable until they are fully healed. Until the stitches are removed, it is important for your pet to rest and avoid vigorous activity like running, jumping, and playing with other pets. A follow-up appointment about two weeks after surgery will allow the surgeon to assess healing and remove the stitches. Usually by this point the patient no longer requires any assistance getting up and moving around, and can resume full activity.

What are the potential risks and complications with a limb amputation?

Amputation is generally associated with a low level of complications. There is a small risk of hemorrhage during surgery, but careful ligation of each vein and artery generally prevents significant blood loss. Following surgery, a fluid pocket called seroma may occasionally form beneath the incision, which can slow healing. Infection of the surgical site is also possible, though uncommon. 

What is the prognosis following a limb amputation?

The prognosis following a limb amputation depends on the underlying condition necessitating the surgery as well as the presence of other concurrent health issues. When an amputation is performed due to severe trauma in an otherwise healthy patient with no other orthopedic or neurologic problems, the prognosis is excellent for long-term comfort and mobility. 

In the presence of orthopedic or neurologic problems affecting one or more of the other limbs, such as arthritis, joint dysplasia, or a compressed nerve, a patient will experience varying degrees of difficulty getting around as they rely more heavily on their remaining limbs; in such cases the surgeon and pet owner must carefully weigh their options before deciding to go forward with an amputation. In some cases, treatment of the other limbs with medications and physical rehabilitation therapy is sufficient to maintain comfort and mobility, while in other cases, the use of a cart may be considered following surgery to take the load off the opposite limb. 

When an amputation is performed for tumor removal, the long-term prognosis depends on the type of tumor. Typically a surgical biopsy is performed prior to going forward with an amputation to determine the identity of the tumor. If it is benign, the amputation will most likely be curative, and the prognosis is very good. If it is malignant, additional diagnostic tests are performed to determine if the cancer has spread to other parts of the body. This will aid in determining the prognosis following surgery. Depending on the type of tumor, chemotherapy may be recommended after the surgical site has healed.

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