Background Information
A medical prosthetic, or prosthesis, is an artificial device meant to replace a body part that has been lost and is intended to restore the normal function of the missing body part. Prosthetics can be created by hand, or with Computer Aided Drafting software (CAD) to design and analyze the creation of the prosthetic with computer-generated 2-D and 3-D graphics alongside other optimization and customization tools.
Old Prosthetics VS New Prosthetics
One of the key differences between old prosthetics and new prosthetics is the use of new materials, such as plastics and carbon fiber composites. These new materials make modern prosthetic limbs lighter, stronger, and much more realistic. In addition, new advancements in electronics have made prosthetic limbs easier for their user to control and made them better at adapting to tasks like gripping or walking.
More recent advancements have even allowed the user to experience touch through the prosthetic by using an electronic skin that is layered over the appendage.
How are Prosthetics made?
While prosthetics are meant to help an amputee restore the function of a missing limb, each amputee is unique. Because of this, each prosthetic needs to be custom-made to fit a patient. Typically the process for making a prosthetic follows the following steps...
Meet with a Prosthetists
Because the reason for needing a prosthetic can vary from person to person, the prosthetic is tailored to that specific patient. In the same vein that dentures or perception glasses are prescribed, prosthetic limbs are prescribed by a medical doctor. This perception is normally given after the doctor meets with an involved physical therapist and a prosthetist.
Under ideal circumstances, this meeting would be done before the amputation occurs and should involve the acting surgeon so that the prosthetist has as much information as possible about the affected limb.
During this meeting, the following questions should be asked to understand what the patient's goals are the during recovery process.
- How active do you plan to be?
- What activities do you plan to do with the prosthetic?
- Do you care what the prosthetic looks like?
- What kind of dressing should be used for the limb? (Usually, this consists of a compression garment that promotes fluid evacuation and healing)
- Measure the Body Segment
Casting of the Stump
Once the measurements are taken, a plaster cast is taken of the patient's stump. This is done so that the prosthetists can have an exact template of the patient's stump for creating the prosthetic. This cast is then used to create a positive mold of the stump.
This is vital to the creation of the prosthetic, as it is important to the doctors that the prosthetic limb fits the patient as accurately, and as naturally, as possible. This step is normally done several weeks after the amputation, to ensure that the residual limb is no longer swollen, and the wound is fully healed.
Creating the Initial Test Socket
The socket is the part of the prosthetic that allows for the replacement limb to connect to the residual limb. The creation of the socket has the prosthetists heat a large sheet of thermoplastic, which is then placed over the positive mold. This is then placed into a vacuum chamber, which forces the thermoplastic to collapse around the mold and into the exact shape of the positive mold.
Check the Prototype Prosthetic's Fit
Before the final prosthetic can be manufactured, the prosthetists need to check the fit of the test socket. This fitting takes place between two to six months after the surgery, as this will allow the wound additional time to heal and reduce any residual swelling.
The prosthetists will place a liner on the stump to provide a layer of protection between the plastic of the prototype, and the skin of the stump. This liner provides an additional cushion for the stump and allows the prosthetic to have a snug fit. If the prototype socket does not fit, then the prosthetists can reheat the test socket and make adjustments.
A poorly fit socket can result in the patient experiencing blisters, pain, and sores to the stump so the patient needs to share how the initial socket feels.
Manufacture the Final Prosthetic
Once the socket is properly fitted to the patient, the final prosthetic can be manufactured. This is done by attaching aluminum or titanium pylons to the socket covering them with a foam cover and die-casting the metal.
The prosthetic is then assembled with a torque wrench and screwdriver to secure the pieces together. The prosthetist has the patient try the prosthetic again and make final adjustments. This prosthetic can last the patient anywhere from several months to several years depending on the patient.
Additional adjustments may need to be made to accommodate the growth and activity level of the patient, so the patient needs to make regular appointments with their prosthetists.