The Science Behind Fabricating Prosthetic Hands and Arms

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The Science Behind Fabricating Prosthetic Hands and Arms

The Science Behind Fabricating Prosthetic Hands and Arms

The process followed to make custom prosthetic limbs requires attention to detail and continuous patient communication. Learn how the prosthetists at Horton’s Orthotics & Prosthetics do it!

Prosthetic limbs may be artificial, but when custom-made, they become realistic appliances that replace arms or legs lost to serious disease, congenital disorders, or trauma. The American Board for Certification in Orthotics, Prosthetics and Pedorthics licenses those who measure, design, fabricate, fit, and service prosthetic limbs as a prosthetist. Working closely with a patient’s physicians, physical and occupational therapists, and surgeons, the prosthetists at Horton’s in Arkansas assist amputees and those with limb loss in regaining overall mobility, limb functionality, and quality of life by providing them with custom prosthetic legs, arms, or hands.

How Prosthetic Hands or Prosthetic Arms Are Made

If you lose an arm or hand due to amputation or abrupt trauma, you have to wait until the wound has fully healed before being measured and fitted for a prosthetic limb. The healing process should facilitate adequate blood flow to the area of amputation, making it strong again to support a new limb. Tests designed to measure blood flow, such as oxygen tension and a skin fluorescent study, are given at this stage to measure blood microcirculation in the residual limb.

When an amputation is pending, a prosthetist can begin measuring for a prosthetic hand or arm before surgery to expedite production of the prosthesis. Amputations caused by unexpected trauma will require the patient to wait until pain, bleeding, and swelling has subsided and scars have adequately healed.

Step 1

Your prosthetist will make a mold of your “residual” limb, or the area remaining from where the arm or hand was amputated. Similar to a dental mold used for fabricating dentures, this residual limb mold is the template necessary for creating a well-fitting, functional prosthetic arm or prosthetic hand. Your surgeon and/or physician will assist your prosthetist by providing information about the location of smaller bones, tendons, and muscles involved in helping the prosthesis be functional.

Step 2

You are then fitted for a prosthetic liner, which is typically made of medical grade silicone. Liners are protective coverings worn over the residual limb to help reduce chafing and excess movement between your prosthetic device and your skin. Ensuring a prosthetic liner fits well and comfortably is just as important as creating a personalized prosthetic limb.

Step 3

Testing how well the prosthesis fits is accomplished by using a thermoplastic sheet covering the model made to fit your residual limb. Sheet thermoplastics are composed of polyethylene and polypropylene. Supporting structures of prosthetic limbs are often made of rigid polypropylene, while the more flexible polyethylene is found in prosthetic interfaces.

Step 4

Following an amputation or trauma, most patients often experience significant fluctuations in muscle and skin volume surrounding the amputation site, along with phantom limb pain and nerve disturbances. If a prosthetic socket is fabricated too early, the resulting socket may loosen and cause you discomfort and instability.

Consequently, a “check socket” may be employed to improve the functional alignment and overall fit of a new socket. Adjustments are easily made with a heating device to optimize your mobility and comfort.

Customized sockets work to evenly distribute mechanical forces across the amputation site and the prosthetic limb’s interface. With laser-assisted methods of measuring sockets available today, you can enjoy an optimal fitting of prosthetic limbs and quick normalization of use.

Step 5

Fabrication of a prosthetic arm or prosthetic hand relies on two plastic manufacturing methods: injection molding and vacuum forming. Prosthetic limbs are made from plastic polymers, which bond fabric-based layers together to make a prosthesis that is strong yet lightweight. Polyester, epoxy, and acrylic are the most used types of laminates, allowing prosthetists complete control over the thickness, stiffness, and strength of a custom-made prosthetic.

Additionally, with the technology available today, your prosthetic hand or arm can also be powered by advanced electronics for greater functionality. Depending on your needs, the options are endless with a custom-made prosthetic limb.

If you need a prosthetic limb in Arkansas, contact Horton Orthotics & Prosthetics at 501-683-8889. We serve patients from our locations in Bryant, Fort Smith, Little Rock, North Little Rock, and Searcy. Schedule an appointment with one of our talented prosthetists today to get started on the path to mobility!

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