Overview of Lower Extremity Amputation
More than 150,000 people in the United States have operations to remove part of their lower leg, like the foot, ankle, or even part of the thigh, every year. This happens more often in people with certain health conditions like peripheral artery disease (which affects the blood vessels in the legs), neuropathy (nerve damage often due to diabetes), and soft tissue infections.
One of the major reasons for this is the increasing number of people with diabetes – a staggering 82% of all leg amputations related to blood flow problems in the United States are in people with diabetes. In fact, individuals living with diabetes are 30 times more likely to undergo an amputation in their lifetime compared to those without diabetes. This staggering number accounts for an annual cost of over $4.3 billion to the U.S. healthcare system alone.
In addition to this, injuries to the lower leg, especially ones with a lot of infection and tissue damage, can also lead to having to remove part of the leg in over 20% of patients. War-related explosions often result in amputations, with 93% of these incidents leading to amputations and about 2% of soldiers in combat losing a limb.
This summary will focus on amputations that take place at the thigh (femur) level or below. This includes above the knee, through the knee, and below the knee amputations. Some foot amputations are also mentioned but for a detailed understanding of these procedures, you should refer to more specialized resources. While these amputations are usually done through surgery, in some rare cases and specific situations, a method called cryoamputation (freezing the tissue) might be used.
Anatomy and Physiology of Lower Extremity Amputation
The lower half of your body, from the waist down, is divided into three main sections: the thigh (the area between your hip and knee), the lower leg (the area between your knee and ankle), and the foot (starting from the heel and extending to your toes).
Your thigh contains the following components:
Front part:
Inner side:
Back part:
The lower leg has the following compartments:
Front part:
Outer side:
Deep back part:
Shallow back part:
The foot comprises 7 tarsal bones, 5 metatarsals, and 14 phalanges. The foot is subdivided into three parts: hindfoot (the back part of the foot that includes the ankle), midfoot (the arch of your foot), and forefoot (the balls of your foot and your toes). The muscles in the foot are either extrinsic (originating from your lower leg) or intrinsic (originating from within the foot).
Why do People Need Lower Extremity Amputation
Amputation is a surgical procedure that involves removing a body part that is causing problems. The decision to perform an amputation depends on many factors like the health of the patient, the condition of the tissue at the intended level of amputation, and the main aim of the procedure, which is usually to cut out any non-viable (dead) and infected tissue.
Generally, the decision to perform an amputation is guided by the quality of the soft tissue and its ability to cover the bone. For instance, if there is enough muscle tissue to cover the bone but there isn’t enough skin, a skin graft (skin taken from another part of the body) may be considered as an option.
People with diabetes or peripheral vascular disease often face considerations for amputation. For example, they might have a foot wound that won’t heal or infected tissue due to reduced blood flow, leading to sepsis (body’s extreme response to an infection) or ischemic necrosis (tissue death due to lack of blood supply). Before deciding on amputation, it’s vital for these patients to have their overall health optimized, such as achieving good blood sugar control and starting antibiotics early to reduce increased surgical site infection risks and preserve as much healthy tissue as possible.
Some people might arrive at the hospital due to a severe injury, such as a high-energy trauma that could lose a limb right away or render it beyond repair. In these situations, many factors like the patient’s overall health status and the potential for a successful reconstruction determine whether the limb should be removed or not. Ideally, the focus should be on life-saving measures first, as these injuries can be life-threatening. The ultimate decision depends on the state of the soft tissues that can cover the bone after amputation.
In some cases, a person may initially seem to have a salvageable limb but might still need an amputation due to complications like infection, the inability to cover bone or hardware, persistent high levels of pain, or a reluctance to proceed with a lengthy course of reconstruction with doubtful functional outcomes.
When a Person Should Avoid Lower Extremity Amputation
People who have advanced peripheral vascular disease, which is a condition where blood vessels outside of the heart and brain narrow or become blocked, often have other conditions such as diabetes, and are usually older with various health issues that can make their bodies weaker. This is why it is often best to ensure these patients’ overall health is improved as much as it can be before any major surgery. However, in some emergency situations, an amputation of the lower limb might be needed to improve the patient’s health condition, but the risks involved, including those from the anesthesia used during surgery, should be discussed with the patient and/or their family or representative.
Some patients might be in intensive care, requiring medications that help the heart and blood vessels, and heavy sedation – medicine that helps a person relax or sleep. These patients’ hearts and lungs might be in a weak state, and although an amputation might be needed, their critical health condition might not allow for a surgery. In these cases, it may be better to wait for the patient’s health to improve before performing an amputation.
A possible solution in these situations is cryoamputation, which involves cooling the limb that can’t be saved to improve the condition of critically ill patients. There are different ways to do this, such as using ice bags, immersing the limb in ice water, using a mechanical refrigeration device, or using dry ice. While this might be difficult to do, with proper training for medical professionals and the setting up of a procedure at the hospital, it can be successfully used. After the patient’s health has improved and the benefits of having an amputation outweigh the risks, a formal amputation procedure can then be performed.
Equipment used for Lower Extremity Amputation
The operation takes place in an operating room that’s completely clean and germ-free. A device called a tourniquet, suited to the patient’s size, is used. The patient lies flat on their back (this is known as the supine position) and they’re either put to sleep with general anesthesia or a regional blockade (a type of anesthesia) is used to numb a specific area only. It’s worth mentioning that in certain cases, some patients may not have blood flowing into a particular area, which means a tourniquet might not be needed. Still, special attention needs to be paid to the skin. To protect it, it’s covered with either a cotton roll or a type of cotton fabric known as a stockinette before the tourniquet is applied.
A ruler and marking pen are used to mark out where the skin and body tissue cut will be made. A large blade (either 15 or 20) is used to make the initial incision into the skin and body tissue. If not, a tool that uses heat to cut and stop bleeding (electrocautery) can be used for the underskin tissue and the entire separation process, but new blades are set aside for cutting nerves. A special saw (either a Gigli saw or power saw) is used to cut through the bones. The power saw can also be used to smooth out the bone ends after they’ve been cut. Otherwise, a bone rasper can be used – this provides a bit more control and might give the front surface of the bone a smoother curve.
If a myodesis (suturing or attaching muscles to bone) is being performed, a drill, a 2.0 mm drill bit and fiber wire sutures (stitches made from a special kind of thread) are used. The tissue is sewn together layer by layer. After the surgery, different kinds of dressings are used to cover the wound, such as petroleum gauzee (gauze soaked in petroleum jelly), soft rolls, battlefield bandages used by the army, and an elastic bandage for pressure.
Who is needed to perform Lower Extremity Amputation?
When a lower leg amputation is done, some key medical professionals are needed. This includes a surgeon, a nurse who works in the operation room, a professional who helps set up the surgical equipment, an assistant to the surgeon, and a doctor who helps you sleep before the operation (an anesthesiologist). There are also medical teams who take care of you just after the surgery. They are crucial in providing immediate care after the operation.
It’s essential for the surgical team to have a detailed talk with the team who will look after you post-operation. This transfer is a critical time to share key details about your health and the reasons for the operation. The doctor can share any difficulties they faced during the surgery, how much blood you lost and what they did to replace it, and what steps were taken during the operation that might impact your recovery.
This hand-off also includes discussing the type of hospital ward you’ll go to after the surgery and any blood tests that need to be done to help monitor your recovery. This ensures everyone involved in your care understands your condition and what next steps need to be taken for your well-being.
Preparing for Lower Extremity Amputation
Choosing the level at which a limb should be amputated is a critical step in planning for the procedure. A method doctors often use to help make this decision involves measuring the amount of oxygen in the skin’s local capillary blood flow, known as Transcutaneous Oxygen Tension (TcPO2). This measure gives an idea of how well blood is being delivered to different areas of the limb. Studies have shown that patients whose post-operation wounds healed well had higher levels of TcPO2.
However, TcPO2 is not the only factor to consider. The patient’s overall health, the condition of their soft tissues, presence of nerve disease (neuropathy), and patient’s daily functioning need to be considered when determining the best amputation level. In certain cases, if a patient’s thigh pulse can be felt, this suggests blood flow in their deep thigh artery is good, and a below-knee amputation can be considered. However, if their thigh pulse can’t be felt, doctors might need to consider amputating above the knee, but they must first check if it’s possible to improve the blood flow.
It’s also essential to discuss with the patient about their likelihood of being independent after the amputation. AMPREDICT is a tool that helps predict mobility outcomes in patients undergoing major lower limb amputations due to complications from diabetes or blood vessel diseases. By understanding their mobility prognosis, patients can better prepare for the considerable recovery period after the surgery. It’s important to note that walking outside the home becomes significantly more challenging as the length of the amputated part increases.
Often, the level of amputation is decided based on the severity of the tissue damage despite getting the best antibiotic treatment. When patients show signs of tissue death because of infection, saving their life is the prime focus. However, doctors also aim to save as much of the limb as possible to maintain the patient’s functionality after the operation.
How is Lower Extremity Amputation performed
The best kind of anesthesia to use for a major lower body amputation isn’t unanimously agreed upon. Some research suggests that there are advantages to regional anesthesia (numbing just a specific area of the body) over general anesthesia, which puts you completely to sleep. Benefits of regional anesthesia include less blood loss, less need for blood transfusion, less need for medication to relieve post-surgery pain, and a quicker return to eating and drinking. On the other hand, a separate study found no difference in heart attack rates or survival rates post-surgery between patients who received general or regional anesthesia. Other research focusing on older patients who were having a major lower body amputation found no difference between the outcomes of regional and general anesthesia in terms of complications like heart attacks, lung problems, strokes, urinary tract infections, and wound problems, irrespective of the duration of the anesthesia or surgery.
In preparing the patient for the operation, irrespective of the kind of amputation to be done, the patient should lie with their back flat. It’s been found that the use of a tourniquet significantly reduces blood loss during the procedure. The surgeon should also scrub the patient’s skin in a circular motion and all the way up to the groin area. The surgeon should cover any wounds on a diabetic or gangrenous foot with a dry dressing and isolate the affected foot using a sterile, waterproof sock. A sealable dressing will further isolate and seal off the incision site.
An important goal of any amputation is to make sure the remaining limb will fit a prosthesis. Skilled surgeons can do this by removing diseased tissue, tapering the bone ends, and creating a cone-shaped limb to suit a prosthesis. It’s also critical to prevent swelling and hematoma (a collection of clotted blood) formation, allow nerves to retract, preserve the length of the remaining limb, and manage post-operative pain effectively.
There are several steps to amputating above the knee, through the knee, or below the knee. These range from making the right shape and size for the incision, using a tourniquet, making further incisions through the muscles, cutting the bones, identifying and securing blood vessels and nerves, potentially ligating (closing off) veins and arteries, and closing the wound with stitches or other closures. The entire procedure should be done in close consultation between the patient, surgeon, and anesthesiologist.
Possible Complications of Lower Extremity Amputation
Leg amputations can lead to serious health complications and even death. Immediate, 30-day death rates following surgery can vary between 4% to
22%. Over a longer period of 1 to 5 years, the death rates can rise up to 15%, 38%, and 68%, respectively. Particularly, for patients with diabetes who undergo leg amputations, the 5-year death rate can reach as much as 77%. Certain factors affect the risk of dying during or after surgery. These include undergoing a type of amputation called ‘above-knee’ (AKA), suffering from heart problems after surgery, being age 74 or older, and experiencing a sudden kidney failure.
A study of 2879 amputees found that following surgery, common complications can include pneumonia in 22% of cases, kidney injury in 15% of cases, deep vein clots (deep venous thrombosis) in 15% of cases, lung injury or distress in 13% of cases, bone infection (osteomyelitis) in 3% of cases, and flap (skin covering wound) failure in 6% of cases.
Complications related to the wound, such as the wound splitting open (dehiscence), collection of fluid (seroma), and pool of clotted blood (hematoma) can happen in between 12% to 34% of ‘below-knee’ amputees (BKA) and 6% to 16% of above-knee amputees. Risk factors for these wound complications can include sepsis (body’s extreme response to infection), compartment syndrome (serious condition that involves increased pressure in a muscle compartment), final stage kidney disease, smoking, being overweight with a body mass index more than 30 kg/m2, and a below-knee amputation. Surprisingly, a study found the use of a special dressing, known as negative pressure wound therapy (NPWT), can reduce the chance of wound complications.
Some patients may also suffer from ‘phantom limb pain’. This is a type of pain that one continues to feel in the area where the limb was removed, even after the tissue has healed. It can feel like a burning, throbbing, stabbing, sharp sensation, or even like the removed limb is still there but in a strange position. This pain can still be present in 67% of patients at 6 months and in 50% of patients at 5 to 7 years after the amputation. Some risk factors for this pain include pain before the amputation, being a female, having an upper limb amputation, or amputations of both upper and lower limbs. Care for a patient who has had an amputation needs to involve a combination of approaches, including the surgical method, pain blockage, medications, physical therapy, and mental health support to reduce the chance of developing ‘phantom limb pain’.
Up to 42% of patients who had a below-knee amputation due to an injury might need revision surgery to adjust the initial amputation. A further 13% might even need to have the level of amputation raised. Risk factors for needing more surgery include being older, presence of a crushing injury, compartment syndrome, or experiencing a major complications after the first surgery.
Finally, psychological distress, such as depression and anxiety, is a significant concern for people who have lost a limb. According to a review, depression can occur in between 20.6% to 63% of patients which is 3 times higher than that in general population, and anxiety in 25% to 57%, which is about the same as in general public. Interestingly, 83% of these patients will need mental health support at some point after their surgery. Extra care needs to be given to the emotional well-being of patients undergoing an amputation, with support and encouragement playing a crucial role.
What Else Should I Know About Lower Extremity Amputation?
Having a limb amputated can make it harder to move around and significantly affect somebody’s quality of life. The loss of a limb means the body has to work harder, which uses more energy. This is particularly true for those who have had an amputation above the knee. For these individuals, research shows energy use increases by as much as 49%, and even more for those who’ve lost both legs above the knee – a staggering 280% more. This is even higher for people who’ve had to have an amputation due to poor blood flow to the limb compared to those who’ve had an accidental injury.
However, the right level of amputation can be decided based on the disease. A through-knee amputation, which falls between the knee and thigh, can be a good alternative to an above-knee amputation if the blood supply and condition of the soft tissues allow it. This type of amputation can lead to a similarly good outcome, but provide better balance and comfort when using a prosthesis, which is an artificial device that replaces the missing limb.
An above-knee prosthesis can rest on the pelvis and might need to be removed for certain everyday activities, like using the restroom. A through-knee amputation might be a better choice for younger patients or anyone who still has the potential to walk. An above-knee amputation might be better suited for those who are bed-bound or have severe vascular disease.
Technology has significantly improved the materials used in prostheses and how well the artificial limb attaches to the remaining part of the limb. Gel liners can protect the skin and help secure the prosthesis in place. There’s also the option for a mechanical pump that can be activated while walking. An ill-fitting prosthesis is the main reason why some people don’t use it because it can cause discomfort. It’s also worth noting that how the prosthesis looks can affect its use. Some patients might be self-conscious about how their limb looks, which can discourage them from using the prosthesis. Thankfully, a silicone cover or sleeve can be designed to look like the other limb, including tattoos and hair.
That’s why it’s essential to involve a prosthetist early in the post-surgery care process. These professionals can help fit a protective sock over the limb and advise on the best prosthesis to meet the patient’s needs.