Amputation and Stump Management

Norman S. Turner

Thomas C. Shives

Indications/Contradictions

Amputation is one of the oldest surgical procedures. Early amputations consisted of severing the extremity, and hemostasis was obtained by dipping the stump in hot oil. Techniques have dramatically improved and most of the advances have occurred during war time. Prosthetic technology now allows for amputees to run, jump, ski, swim, and be involved in competitive sports.

The indications for above and below knee amputation include life-threatening infections, malignant tumors, burns, extensive frost bite, congenital anomalies, ischemic pain, osteomyelitis, extensive trauma (including a tibial nerve ilaceration or unreconstructable vascular injury) and chronic pain. The most common indications for a below knee or above knee amputation are complications of diabetes. Functionally, the patients with below knee amputation are able to walk with prosthesis, with most patients walking within 3 months after surgery. Amputation should not be viewed as a limb salvage failure, but as a reconstructive procedure to improve function.

There are few contraindications to amputations; however, a contraindication to a below knee amputation is a non-ambulatory patient. A non-ambulating patient with a below knee amputation is at high risk for developing a flexion contracture, which can result in increased pressure on the stump and cause ulceration. Therefore, when a patient is wheelchair bound and is not a candidate for prosthetic fitting, an above knee amputation should be considered.

Preoperative Planning

It is imperative that these patients be evaluated preoperatively to determine the vascular status of the limb. The majority of patients undergoing a below knee amputation or above the knee amputation have diabetes and have some component of peripheral vascular disease. Preoperative noninvasive vascular studies, including ankle brachial indexes, are important to determine the level of amputation. An ankle brachial index is determined by measuring the ankle systolic pressure and dividing it by the brachial systolic pressure using Doppler detection of the pulses. The severity of the arterial disease is related to decreased value of the ankle/brachial index (ABI), and a value of less than .5 is considered abnormal in people with diabetes. Also, noninvasive vascular studies using transcutaneous oxygen tension measurement (TcPo2) are useful in assisting with amputation levels. Amputations are likely to heal if the TcPo2 measurements are greater then 40 mm Hg. Patients with TcPo2 values less than 20 mm Hg are at higher risk for not healing and should be evaluated with further vascular testing and possibly an angiogram before surgical intervention. A vascular surgery consult is almost always indicated before performing an amputation. With the advances in distal bypass surgery and invasive radiologic procedures, certain patients can be successfully treated with limb salvage after vascular reconstruction.

Imaging studies are important in determining the underlying pathology. Imaging of the tibia or femur is important if there is a question regarding extension of tumor or infection into the tissues or
bone adjacent to the intended level of amputation or if there is a prosthetic device such as a total knee arthroplasty or internal fixation device in place, which may alter the surgical procedure.

If amputation is contemplated, optimizing the patient’s medical condition before surgery is recommended. Literature has shown that patients with a serum albumin less than 3.5 g/dL or true lymphocyte count less than 1,500 cells per mL are at high risk for wound-healing difficulties.

Determination of the amputation level is important for both healing and function. The more distal the amputation level, the less energy required to ambulate. In elderly patients, a more proximal amputation may not allow for ambulation secondary to energy requirements. If a patient has good cognitive function, balance, and strength, then the most distal level with a realistic chance of healing should be attempted.

Surgery

In order for the below knee amputation to be performed correctly, proper attention to detail is important to improve the quality of the result. Gentle handling of the soft tissues, especially in diabetic patients, is important to minimize wound complications. The level of the amputation is determined by the extent of the infection, tumor, or the level that would provide optimal function with prosthesis. In general, the patient is positioned in the supine position for above or below knee amputations.

Full-thickness flaps should be used to minimize skin edge necrosis. Meticulous hemostasis and use of a drain is imperative to decrease the risk of a hematoma. The nerves should be divided sharply under tension to minimize the risk of a symptomatic neuroma. Also the bone ends are rasped until smooth to prevent bony prominences.

An open amputation is performed in patients with grossly contaminated wounds or in patients with extensive infection. These patients will require further surgeries to optimize the soft tissues around the stump, and then a definitive closure can be performed once this is accomplished.

Technique

Below Knee Amputation

Below knee amputation is the most commonly performed lower extremity amputation. A long posterior flap is used and brought anteriorly to cover the distal stump of the tibia, which should be 8.5 to 12.5 cm in length (Fig. 31-1). The flaps, if planned properly, will have minimal redundant skin in the corners, or “dog ears.” This will provide a good prosthetic fit.

The patient is placed supine on the operating room table. A nonsterile tourniquet is used and the leg is prepared and draped in the usual fashion. A skin marker is used to plan the flaps (see Fig. 30-1), and the flaps are drawn so that the posterior flap begins two-thirds of the way posterior to the anterior aspect of the tibia and then extends distally and posteriorly so that the distance will be long enough to cover the tibia (Fig. 31-2). A tourniquet can be used at the discretion of the surgeon. The incision is then made through the skin and subcutaneous tissues down to the fascia. The subcutaneous nerves including the saphenous and sural nerve can be identified and divided under tension. The fascia is then incised. The anterior compartment musculature is cut with a cautery (Fig. 31-3) down to the deep peroneal nerve, which is identified and cut under tension (Fig. 31-4), and the anterior tibial artery is identified and tied with silk suture (Fig. 31-5). The superficial peroneal nerve is identified and cut under tension. The periosteum is reflected off the tibia (Fig. 31-6), and the tibia is cut 1 cm proximal from the skin incision (Fig. 31-7). A segment of the fibula is then resected 1 cm proximal to the tibial bone cut (Figs. 31-8 through 31-10). Traction is applied, and an amputation knife is used to perform the remaining portion of the amputation (Fig. 31-11). Dissection is carried deep until blood from the posterior tibial artery and vein is identified, and then the cut is beveled distally until the fascia is cut (Fig. 31-12). The anterior aspect of the tibia is beveled (Fig. 31-13). The remaining edges are rasped until smooth. The tibial nerve is identified and transected under traction (Fig. 31-14

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