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Amputation and Prosthetics


Amputation has been around since ancient times. It has evolved from the quick, speedy, and unhygienic surgical techniques they had then, to what we now know as a careful and delicate surgical dance, designed to give the patient their best quality of life. Prosthetics have also advanced, from peg legs, to synthetic socks and, lightweight carbon materials, to bioengineering technology that allows patients to control their prosthesis like a real limb. The standard amputation procedure gives patients a lesser quality of life, where they are in pain and have poor prosthetic control, the Ewing and Osseointegration surgeries are better for a patient's mental, physical and emotional state, improving phantom limb pain and other common issues amputees worry about.


Standard Above Knee Amputation

Trauma, infection, a tumor, or vascular compromise can be blamed for the need of amputation. With the standard Above the Knee Amputation (AKA), the surgeon cuts through the femoral bone and thigh muscle which is divided into three compartments, the anterior, posterior, and medial muscles. But is amputation always necessary? Studies have been performed in an attempt to create algorithms, which give doctors feedback on whether amputation or reconstruction is the best move, medicinally. If amputation is the best option, some patients are not fitted for a prosthesis right away as they do not have the money. These patients ultimately end up in a wheelchair; but wheelchairs are movement restrictive and mobility is severely affected. So where do you graw the line? This is obviously a no-win situation, but making it as easy to deal with as possible, is in the best interest of the patient and doctor.


The Ewing Procedure

When you flex your ankle, the muscles in the front of the leg contract, while the muscles in the back of the leg stretch, when the ankle extends the muscles switch roles. In these muscles, there are nerves that send signals to the brain so that we can use proprioception to determine the position of the limb without seeing it. The standard operating procedure breaks this relationship, therefore, making the brain unable to use proprioception in this limb. AMI (agonist-antagonist myoneural interface) translates proprioceptive information from the bionic limb. During the Ewing surgery AMI is performed, meaning that a synthetic device is connected to the nervous system, which provides proprioception after the limb is amputated. AMI is created with two muscles, an agonist and an antagonist, when surgically attached (in the residuum) these muscles work like normal muscles, in that they allow us to use proprioception. Agonist and antagonist pulleys are created over the bone to re-link the muscles and tendons, preserving the relationship between the muscle and the brain. This re-link allows next-generation prosthetics (in this case a socket prosthetic) capable of natural ankle movement to be connected to the residuum. When the patient wants to move the bionic limb, the AMI muscles that are associated with the joint motion intended, contract. Electrodes (in the tissue) next to the AMI send signals from the muscle to the prosthesis's computers, which use the signals from the muscle to control the movement of the prosthesis in a natural way. Due to the fact that the AMI muscles are connected within the residuum, when the agonist contracts the antagonist stretches (working like a pulley system) . This relationship allows the sensors in the muscles/tendons to send electric signals to the central nervous system, telling the brain the muscle’s length, speed, and force which tricks the brain into thinking the residuum has its original proprioception. Jim Ewing was the first patient to have the AMI implanted in his remaining limb (the procedure was later named after him). He stated that when blindfolded, he was able to locate his ankle-foot and sense its movement. Jim displays natural reflexes while walking up and down stairs. The way that Ewing moved and controlled the bionic limb as if it was a part of him, proves neurological embodiment. Their is also a lack of atrophy and phantom limb pain (PLP) in the AMI patients; this indicates that AMI provides life changing benefit.


Osseointegration Procedure

Osseointegration is recommended for patients who do not tolerate or want to use a socket prosthetic. This technique is commonly used in dental implants and joint placements. After the amputation, the surgeon will take the custom made titanium rod and permanently implant it into the bone, which will later grow into the growth plate. This procedure can be done with the femur (upper leg bone), tibia (shinbone), humerus (upper arm bone), radius (one of the two bones in the lower arm), and ulna (the other of the two bones in the lower arm). Patients who get this procedure have improved mobility, proprioception, reduced nerve pain, and are without common socket problems such as pinching, skin irritation, and lack of control. The implanted metal rod provides the amputee with greater physical control and more of an emotional connection with the prosthesis. The fact that the rod is implanted into the skeleton, provides the patient with more strength, energy, stability, and a smoother walking experience. With arm prosthetics, there is the option of myoelectric prosthetics which is an artificial limb controlled and moved by the electrical signals sent off by the amputee’s muscles. Compared to the normal socket prosthetic, osseointegration does not put pressure on the remaining limb. The pressure is known to worsen PLP and if pain is still present there are surgeries that can ease PLP; they are the Regenerative Peripheral Nerve Interface (RPNI) and Targeted muscle reinnervation (TMR) surgeries .

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With the standard amputation procedure, patients struggle with physical and mental pain; the Ewing and Osseointegration surgeries improve and in most cases completely remove this hardship. The advantages of these surgeries leave the patients feeling almost whole again. If not for today’s technological and engineering advancements we would still be using peg legs and hooks. It’s funny how things take time to advance and do it in a slow manner, but once it happens the possibilities for expanding are endless.

It IS Possible!

Jim Ewing after amputation

Jim Ewing after amputation

© 2020 Brooke Jolie

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