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Above Knee Amputation

Your leg has been amputated above your knee and below your hip joint. More energy will now be required to mobilise than a below knee amputee, however the functioning hip joint and femur will help drive the prosthesis. The longer the femur that still allows for the fitting of a suitable knee component is better in this case, as it serves as a longer lever to assist with propulsion. There are a few more components needed than a below knee prosthesis so your main components that will be required are a comfortable socket, a suitable prosthetic knee and a prosthetic foot. 

The need for above knee amputation may be as result of one of the following conditions:

  • Peripheral vascular disease (poor circulation)
  • Diabetes
  • Infection
  • Foot ulcers
  • Trauma causing the lower leg to be crushed or severed
  • Tumours

What is an Above-Knee Amputation?

An Above Knee amputation, also known as a Trans Femoral amputation, is a surgical procedure performed to remove the lower limb above the knee joint when a limb has been severely damaged or is diseased. Most transfemoral amputations are performed due to peripheral vascular disease (a complication of diabetes), or severe circulatory diseases in the lower limb. Poor circulation limits healing and immune responses to injury. Ulcers on the foot or leg may develop, which they may not heal and become infected. As a result, the infection may spread to the bone and become severe enough to be life-threatening.  

The amputation is then performed to remove the diseased tissue and prevent further spread of infection. Transfemoral amputations are performed when the blood flow is inadequate in the lower leg or infection is so severe it prohibits a lower-level (below the knee) amputation. Other reasons for amputation may be as a result of trauma, disease, or congenital defect 

When an Above Knee amputation is necessary, it is usually performed by a vascular or orthopaedic surgeon. The diseased or severely injured part of the limb will be removed, keeping as much of the healthy tissue and bone as possible. The surgeon shapes the remaining limb to allow the best use of a prosthetic leg after recovery. The correct length of the residuum, that includes healthy tissue and bone is retained to provide a good length lever to help propel the prosthesis and this is better for stability and energy usage. A shorter residuum requires more energy to control and propel the prosthesis. 

Above Knee Amputation – the positives

While an amputation is never ideal, there are some positives when it comes to an above knee amputee: 

  • An Above Knee prosthesis usually easier to use than an amputation at a higher level, such as through hip. The higher the level of the amputation the more energy is required to ambulate. 
  • Depending on your physical condition and with proper training on the prosthesis, independence from assistive devices such as crutches can be achieved after 4 to 12 weeks from the date of receiving the prosthesis. 
  • Swimming, running, returning to sports are all possible depending on your physical condition and your prosthetic components. 

Discussing what you would like to achieve in the future with your prosthesis is an extremely important conversation to have with your prosthetist. Knowing the limitations and understanding what is possible and what isn’t possible with a prosthesis will help set your expectations as the prosthetic user. 

The Socket

As with all prosthetic sockets, the fit is extremely important. An Above Knee socket is custom made according to the shape and size of the residual limb. The prosthetists expertise come into play with the socket design and understanding of your unique needs. The prosthesis is suspended by various methods that will be discussed during your assessment. The socket design is unique to you, we generally use a method where we use the skeletal ischium (sitting bone) and hydrostatic pressure (total contact) on the residual limb. It is quite important that you discuss with your prosthetist any concerns you have or explain as best as you can where you are feeling pain or discomfort in your socket. You are the one wearing it and you need to be comfortable in it. 

The prosthesis is suspended by various methods, these methods will be discussed during your assessment. The main suspension methods are vacuum (active or passive) or via pin lock. Both methods have pros and cons, your prosthetist will advise you on the method they recommend based on your specific needs. For suspension we generally make use of a liner, either made from  a silicone, gel or polyurethane liner. The liner is soft “sock” that is rolled on to your residual limb to forma soft and protective layer between your residual limb and the socket. 

The Prosthetic Knee

The prosthetic knee joint allows both flexion (bending) and extension (straightening) and varies in function depending on your needs, weight and activity levelThey vary in function as a result of these factors, from basic locking knees that stay straight when you are walking to high functioning hydraulic knees that are controlled by built in microprocessors. Your prosthetist will assist in selecting the knee that is right for you based on your needs.  

Our prosthetists are experienced in using a wide range of knee joints and we are manufacturer certified to fit high end components including the X3, Genium, C-leg and Rheo XC Knee joints. 

The Prosthetic Foot

The prosthetic foot chosen will be based on your weight, activity level and specific needs. There are a wide variety of feet available and options will be discussed with you in detail ensuring we match your foot to your needs. Prosthetic feet vary in their capabilities depending on the level of activity they are selected for. Some are activity specific such as running blades, they are designed specifically for running and not for day to day walking due to their energy return capabilities. They are designed for you to put a lot of weight/energy into the foot for it to release energy to propel you forward, as you can imagine, not ideal for day to day walking. The same could be said for an entry level foot, its purpose is to facilitate a smooth roll over while walking and provide a broad base of stability. Trying to run with this type of foot will lead to it failing and can cause pain or discomfort to your residual limb. 

The Look of the Prosthesis

This is determined by the shape and size of your residual limb as well as the intended use of the prosthesis. Some prosthetic users like to have the components of their prosthesis exposed, others a High Definition silicone cover to match their sound limb. The decision is yours and again this is something that needs to be discussed with your prosthesis so they can advise on what is possible and what isn’t. Setting expectations in this regard is extremely important. 

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