Above-the-Knee Amputation

By Meg Marinis, Director of Medical Research Nov 29, 2012
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Wasn't it awesome to hear Arizona laugh again? And see her in those navy blue surgical scrubs? I know I'm not the only one who has missed seeing Dr. Robbins in the hospital. And let's be honest… Arizona's come a long way. Over these past several months, Arizona has been put through a physical and emotional gauntlet. Let's take a look back at her journey, and see where Arizona might be headed in her continuing recovery. 

When the plane crashed, Arizona suffered a severe open fracture to her thighbone.

By the time they were rescued, her wound had already become extensively contaminated, and she had started to develop an infection. Her doctors desperately tried to treat it with multiple antibiotics, but the infection continued to ravage Arizona's body, causing her to become septic. The bacteria quickly spread through her bloodstream and would have killed her if they had not eliminated the source of the infection: Her leg.

Alex performed an above-the-knee (AK) amputation on Arizona. Internationally, this type is also known as a transfemoral amputation because it occurs in the thigh, through the femoral bone. According to the Amputee Coalition of America, almost one of every five people living with limb loss in this country has a transfemoral amputation. Besides severe infection, other indications for an AK amputation include:

• Trauma or injury.
• Poor blood flow that cannot be corrected, resulting in tissue loss or pain.
• Tumor.
• Congenital disorder.
After her surgery, while recovering at home, Arizona needed to undergo extensive physical therapy before being fitted with a prosthesis.

Depending on how fast the residual limb heals, most patients have their stitches removed within three to four weeks after surgery. However, doctors instruct lower-limb amputees to begin pre-prosthetic physical therapy as soon as possible. Unlike below-the-knee (BK) prostheses, AK devices do not sufficiently help with transfers or in rising from a sitting to a standing position because they no longer have knee strength. Therefore, these patients need to strengthen their other limb, torso, pelvis, and arms in order to ensure that they will be able to use a prosthetic device safely. Before a prosthesis may be fitted, amputees should be able to do the following:

• Transfer independently, both in and out of bed and on and off the toilet.
• Go from a sitting to a standing position independently.
• Walk in parallel bars or with a walker for at least 25 feet.

Along with physical therapy, in order to prepare for a prosthesis fitting, amputees often begin "desensitizing" their residual limb. By rubbing it and manually moving around the tissue, the amputee can help to loosen any scar tissue that may develop.

After her incision healed, Arizona met with her prosthetist to be fitted for her postoperative socket.

First, what is the socket? The socket is the part of the prosthesis that attaches it to the body and basically determines whether it will comfortably fit. Most amputees believe the socket is the most important aspect of a prosthesis. The other three aspects of the prosthesis include: the suspension, the components, and the alignment.

But in this initial fitting, the amputee needs to be measured and "cast" – As we saw in the episode, this process can be done either manually with plaster wrapping or by scanning to create a digital image of the limb. Either way, the prosthetist needs a model for the limb in order to create the socket. Once made, the socket will then be connected to a simple knee, which is then connected to a prosthetic foot. The prosthetist will examine and question the amputee in how the socket fits, making adjustments as needed. Once a level of comfort has been established for the socket, the remaining components will be added, and the amputee has their first prosthetic leg. However, the amputee will still need to attend physical therapy two to three times a week in order to train and become more accustomed to the prosthesis.

Arizona's residual limb will continue to change as she uses her prosthesis more.

Due to volume loss, Arizona's residual limb will continue to shrink for possibly up to nine months. Most AK amputees end up visiting their prosthetist on a monthly basis and even need socket replacements because they have become too large. Many amputees voice frustration at this stage because every socket feels differently and takes time to adjust to its fit. However, once the residual limb stabilizes in volume size and matures, the amputee will be able to consider a more definitive option for their prosthesis. Arizona's prosthetist will choose an appropriate permanent option by taking into account her job and potential level of activity.

For more information on tonight's Public Service Announcement and for resources on living with limb loss, please visit:

http://www.amputee-coalition.org/