What Are Prosthetics and Orthotics?
According to the Amputee Coalition, approximately 185,000 amputations occur in the United States each year, and a staggering 3.6 million people will be living with limb loss by 2050 [1]. Given the loss of self esteem and distorted body image, about 30% of new amputees undergo severe depression [2]. In addition, many families lose their main source of income, given that amputees may no longer be able to work in their respective fields. This is why many families look into obtaining an artificial limb, or a prosthesis. But what exactly are prosthetics, and what type of patients would need it? Prosthetics is the practice of creating an artificial limb that helps a person with limb loss carry out their day-to-day activities [3]. According to Johns Hopkins University, around 54% of all amputations are surgical amputations that result from vascular diseases like diabetes and peripheral arterial disease. About 45% of all amputations are caused from industrial and occupational accidents, however, less than 2% are caused by cancer [4].
There are two types of prostheses: those replacing upper limbs and those replacing lower limbs. The upper limb prostheses deal with reaching and grasping, while lower limbs deal with standing, walking, shock absorption and much more. Prostheses are completely custom made for each patient depending on their needs. For example, if the patient is very active, they could look into getting a blade runner; if the patient likes to swim, they could look into getting a water prosthetic leg.
However, some patients do not need an artificial limb but rather a device that would correct or support the patient's body. These patients should look into orthosis. Orthotics is the branch of medicine that deals with support braces or splints to align, support, or prevent the function of movable parts of the body. Like prosthetics, diabetic patients are the most common for orthotics due to their high blood pressure. With high blood pressure, it damages the arteries making them less elastic and in turn does not allow proper blood flow to the rest of the body. Other instances where orthotics might be needed include arthritis, back pain, bunions, flat feet, and many more.
Many common products are orthotics, including shoe inserts. The purpose of custom shoe inserts is to correct abnormal walking or reduce blistering and inflammation by altering the angles at which the foot strikes the ground. Some other examples are HALOS, which immobilize and protect the bones in the neck, and custom cranial helmets for infants with positional plagiocephaly, a condition in which specific parts of an infant's head develop a flattened shape.
The Process of Creating Prosthetics?
I had the pleasure of working at the Beverly Orthopedic Laboratory and experienced the process of how patients are diagnosed and treated with prosthetics. The Beverly Orthopedic Laboratory is a full service company that fabricates and fits both prostheses and orthoses.
To actually make a prosthesis, the prosthetist first starts by taking measurements of the target area. Next, they begin to cast the area, which serves as the plaster filler to create the mold. Using the mold, they make a transparent test prostheses to check the fit and to see if there are any red marks or blisters forming on the stump. Using that model of the stump, the technician or prosthetist heats up a plastic sheet (PETG) and lays it over the mold in a vacuum chamber. While the air is getting sucked out, the plastic sheet begins to collapse over the mold taking the exact shape of the molding. After the test fit is completed, the practitioner will give it to the patient and will work with the patient to relieve some stress on certain areas of the prosthesis.
There are many methods for molding the permanent socket, the socket that a patient puts the limb in and is used for the patient's permanent prosthesis. For example, the Beverly Orthopedic Lab uses lamination, because it is the safest and best way compared to injection molding or forcing molten plastic into the mold, both of which have a high chance for error and can injure the technician. The technician wraps the molding with carbon fiber and allows resin to drip over it to make it hard. A pylon, usually made of titanium or aluminum, is attached to the socket for support. For the lower limbs, a locking system is required and will vary depending on what the patient wants and how the body will react to it. For example, a new patient will not use a suction or vacuum suspension, because their body mass will be constantly changing to adjust with the new lifestyle. The three locking systems are the lock and pin method, elevated vacuum and suction locking.
The lock and pin has a pin attached to a silicon liner that is put on the stump. The pin is inserted inside a pinhole which then locks the stump in place.
Elevated vacuum suspension uses an active pump to create negative pressure which means that it will be constantly pulling the limb in the socket [5].
The suction locking system is a sealed chamber in the socket. The suction suspension is created during the swing phase of the person's stride, which creates the negative pressure [5].
The other components are put on by using either adhesive or bolt-ons, the latter of which are more used for permanency. To make it appear human-like, the technician will cover the limb with foam to match the patient's skin tone.
The Future of Prosthetics and Orthotics
The field of prosthetics and orthotics is constantly growing, and each device is an improvement on the previous one. The prosthetic device is very complex, but scientists are working on making them simple. Many patients don’t wear their prosthesis or orthosis due to it causing too much pain. Since they do not wear it, many of their issues become worse and lead to more pain. The best course of action to solve these issues is to make prosthetics and orthotics more comfortable and discreet, thereby encouraging people to wear them for a longer period of time .
In the near future, bionic arms and legs will prevail. There are many companies researching to create an artificial limb that replicates the human arm. Many of them are using neurology to improve prosthesis through a field of study known as neuroprosthetics. For instance, Dr. Sliman Bensmaia of the University of Chicago has been researching bionic prosthetics that allows the user to actually touch and feel objects. By putting “electrodes in the motor cortex,” Bensmaia and other researchers have created a method so when [a tetraplegic patient] tries to move their arm, or imagines moving their arm, there is a characteristic pattern of activation in this motor part of the brain” [6]. Furthermore, Sweden has also been researching a new bionic prosthesis that can be controlled with the mind. This prosthesis is directly attached to the bone through a process called osseointegration, which completely eliminates the use of sockets and the discomfort that patients experience with a normal prosthesis. In this new creation, electrodes are attached, which will pick up the brain's signals and allow the user to move the limb in natural ways [7].
With new advances in the biomedical field, such as nanorobotics and tissue engineering, the prosthetic field continues to grow at a rapid pace. In the near future, it won’t be surprising to see a prosthesis that can replicate the movements of any limb.
[1] “Amputee Statistics You Ought to Know.” Advanced Amputees, 2012, advancedamputees.com/amputee-statistics-you-ought-know.
[2] Hashem, Mariam. “Emotional and Psychological Reactions to Amputation.” Physiopedia, www.physio-pedia.com/Emotional_and_Psychological_Reactions_to_Amputation.
[3] Davis, Charles Patrick. “Medical Definition of Prosthetic.” MedicineNet, MedicineNet, 29 March 2021, www.medicinenet.com/prosthetic/definition.html.
[4] Shores, Jaimie Troyal. “Amputation.” Johns Hopkins Medicine, www.hopkinsmedicine.org/health/treatment-tests-and-therapies/amputation.
[5] Amputee Store. “What Is the Difference between Vacuum and Suction Suspension Systems?” Amputee Store, amputeestore.com/pages/what-is-the-difference-between-vacuum-and-suction-suspension-systems.
[6] Wood, Matt. “UChicago Neuroscientists Expand Possibilities for Realistic Prosthetic Limbs.” University of Chicago News, 9 Sept. 2020, news.uchicago.edu/story/uchicago-neuroscientists-expand-possibilities-realistic-prosthetic-limb.
[7] “In the Media: The Future of Prosthetics Might Be in This Mind-Controlled Bionic Arm.” day.yale.edu/news/media-future-prosthetics-might-be-mind-controlled-bionic-arm.
