There are few events more traumatic than experiencing the amputation of a limb or appendage. It is impossible to realize just how much you rely on your lost body part until you no longer have it. Fortunately, advancing technology in prosthetics has made the process of replacing missing limbs or appendages easier and more comfortable than ever. This was not always the case.
What is Prosthetics?
Prosthetics refers to the science and art of creating and fitting artificial body parts. The parts themselves are referred to as prostheses or a prosthesis as a singular part. A prosthesis is designed to enhance a person’s life by helping them regain the function they lost alongside of their limb. While it is tempting to think of these parts as simple reconstructions of an actual limb, a prosthesis must combine materials, alignment, design, construction, and function in order to mimic the actual limb’s movement, weight bearing capabilities and appearance.
Why Would Someone Need a Prosthesis?
Amputations, the surgical removal of a limb or appendage, occur for a variety of reasons. Most commonly, an amputation happens as a result of disease that limits the blood supply to a part of the body. Diseases such as diabetes and cardiovascular disease account for the majority of amputations that happen as a result of disease. Only 25 percent of amputations happen as the result of an accident. Regardless of the cause, anyone who seeks to regain mobility or function they have lost as a result of an amputation may be eligible to receive a prosthesis. These are generally divided into two descriptive categories based on where they are used in the body. Lower-limb prostheses can be used to give a person stability when they stand and walk and require a certain amount of shock absorption when walking or even running, jumping or weight lifting. Upper-limb prostheses refer to those placed on the upper body and may give a patient the ability to reach, hammer, paint, lift, or perform normal daily activities like eating, drinking, dressing, or writing.
What sets Advantage Prosthetics & Orthotics Apart From Other Prosthetic Providers?
Advantage Prosthetics & Orthotics’s highly trained, expert clinical staff treats patients with a variety of diagnoses. Not only are our providers sensitive to each individual’s needs, we believe a prosthesis should fit well, perform well and change as your body and fitness levels change. Once your limb or appendage has healed from amputation, the design and fabrication process can begin. The first replacement body part, known as an early-fitting or temporary prosthesis, is simply a starting point for a long and customized experience. Many modifications will be made to address fit, comfort and function as well as your current health and fitness goals. As your limb continues to heal, your definitive prosthesis will be made that will be functional, lighter and cosmetically finished for a more natural appearance.
Our clinical staff understands that the prosthetic process can be painful and frustrating. You have lost a part of your body. You will experience stages of grief as well as varying levels of anger and resentment about the experience. Fortunately, our caring practitioners can help you work through these feelings as you begin the process of replacing your lost limb. For more information or to schedule a consultation, contact us today.
A (Brief) History of Prosthetic Limbs
Amazingly enough, prosthetic limbs date back to Ancient Egypt where amputees wore them, not necessarily for function, but to maintain a sense of wholeness. However, scientists recently discovered a mummy with a functional, prosthetic toe that appears to beat the assumption that all early prosthetic limbs and appendages were decorative. That trend continued into the Dark Ages where most prosthetic limbs were made from iron or wood and served mostly as a filler body part. Romans were fitted with prosthetic arms that would hold shields in battle. Knights would wear prosthetic legs to appear normal in stirrups. Only the most wealthy would be fitted with iron or wood prosthetic limbs (mostly peg legs and hook hands).
It was not until the Renaissance, and the early 1500’s that doctors and inventors began to pay attention to the function of prosthetic limbs. Springs and straps were introduced to upper extremity prostheses making it possible for a person to do everyday things like remove their hat or sign their name. In 1529, Ambroise Paré, the man commonly revered as the father of modern amputation surgery and prostheses, introduced an above-the-knee prosthesis with a locking, bending knee that allowed someone with a prosthetic lower limb to walk more normally. From there, war and inquisitiveness led inventors, aviators, and engineers to discover new ways that prosthetic limbs could mimic the movement of human body parts.
Prosthetic Limbs Today
Today’s prosthetic limbs are far cries from early wood or iron versions. They are designed to enhance a person’s life by helping them regain lost function as well as restore the appearance of the limb. While it is tempting to think of these parts as simple reconstructions of an actual limb, a prosthesis must combine materials, alignment, design, construction, and function in order to mimic the actual limb’s movement, weight bearing capabilities and appearance. Today’s much lighter and more versatile prosthetic limbs are typically made from plastic, aluminum or composite materials that make them easier to remove, easier to wear and more functional than their early counterparts. Most include silicone covers that give them a more natural looking appearance. Custom molds are created for every residual limb in order to properly fit a prosthetic limb to the person wearing it with silicone inserts making using the device more comfortable than ever.
What a prosthetic limb is made of is not the only advance in prosthetics in recent history. The ever-advancing world of biomechanical engineering has also made strides in how these limbs react to muscle movement and neurological signals of the wearer. Researchers are using robotics and microprocessors in prosthetic limbs to allow the wearer to control them with muscle movements of the remaining limb or even their “thoughts”. Engineers at Johns Hopkins University are creating Modular Prosthetic Limbs that rely in mapping of the remaining nerves in the arms or legs to control the new limb. Many wearers even report being able to “feel” through the skin on the limbs because of information being sent back to the brain through one of more than 100 sensors on the prosthesis. Not only are people able to regain gross motor skills, they are able to control fine motor movement and regain “sensation” in the prosthesis. While we are still several years off from this being the norm, advances in robotics mean more functional prosthetic limbs are on the horizon for all who need them.
What are Prosthetic Limbs Made of?
Most prostheses consist of five different parts – a custom fitted socket, a pylon or the internal structure of the prosthesis, a way of attaching it to the body, a means of cushioning the point of contact and (when requested) some form of realistic looking silicone skin. Generally, the socket is made of some form of plastic for its ability to be molded and shaped based on casts of a person’s remaining limb or tissue. Polyethylene, polypropylene, acrylics and polyurethane are the most common plastics used for this task for their durability and ease of use. Titanium and aluminum have replaces steel that was used in early days of pylon construction. More recently, carbon fiber has become common in the creation of pylons for its lightweight construction. While early prosthetic socks that cushioned the remaining limb were made from wool, today’s advances in plastics have made it possible to create lightweight, moisture wicking, silicone cushioned socks for more comfortable wear and better care of the skin on the remaining limb. Finally, in an effort to make the prosthesis appear more lifelike, most are covered with a soft polyurethane coating designed to match the shape of the patient’s remaining limb. It is then covered with artificial silicone “skin” painted to match the patient’s skin color or a sock that covers the prosthesis completely.
How are Prosthetic Limbs Made?
Unlike many medical devices, prosthetic limbs are not mass-produced for purchase at a local pharmacy. Once a prosthesis is prescribed by a doctor, the patient visits a prosthetist to be fitted with a limb. First, the patient must be measured and have the remaining part of the limb cast or digitally measured. Since the ultimate goal is to have a prosthesis that matches the patient’s appearance, lifestyle and comfort level, this step is one of the most vital parts of the fitting process. The prosthetist will determine where the bones and tendons are in the residual limb and measure the lengths of different body segments in the remaining limb to create a prosthetic that will complement the user’s existing body parts.
Once the impression of the residual limb is made, the process of creating a socket can begin. A positive version of the residual limb is created from the plaster or silicone mold. A heated sheet of thermoplastic is laid on top of the perfectly cast mold in a vacuum chamber. The air is then sucked out of the chamber, forcing the sheet of plastic to collapse around the mold into its exact shape. Once it is cooled, this plastic is now the test socket for the patient’s prosthesis.
The patient returns to the prosthetist where the test socket is fitted on the patient’s residual limb. The patient is encouraged to be completely honest about how the socket feels. Since it is made from thermoplastic, there are limitless micro adjustments that can be made in order to create a socket that is comfortable and functional. In many cases, these test sockets are made for limbs that are still healing from amputation. The idea is that once the limb shrinks and adding prosthetic socks can no longer hold the limb on, a new socket will be made that fits properly to the new size of the residual limb.
Once the patient and prosthetist are satisfied with the fit of the test socket, the permanent socket is formed from polypropylene. Using the same method as the test socket, polypropylene plastic is vacuum heated over a mold of the residual limb, and then minor adjustments are made once the socket is affixed to the intended wearer
Once the socket is made, there are many ways to create a prosthesis. Plastic pieces are either molded, extruded or vacuum-formed the same way sockets are created. Pylons that are made from titanium or aluminum are typically die-cast when liquid metal is forced into a steel die. Wood pieces that are still often used for feet or hands in basic prostheses are shaped the same way most wood projects are created – with drills, saws and smoothing tools. These pieces are then put together using bolts, adhesives, laminating materials, or even more secure joints and locking mechanisms that allow for greater security and better movement. Once assembled, the prosthesis will be fitted to the patient and any adjustments can then be made.
What Do Prostheses Cost?
Depending on the level of amputation and functionality you need in your prosthetic limb, costs can range from $3,500 for the most basic model to $50,000 for more advanced prostheses with myoelectric functions that react to the patient’s muscle signals. Many insurance companies will cover prostheses after amputation, offsetting some of the cost. Yet being fitted for a prosthetic limb is not a one-time event. Most prostheses are only meant for three to five years of wear and tear. If the patient is a child that is still growing, prostheses will need to be replaced at a minimum of every two years to keep up with the growth of the child’s remaining limb. Imagine having a child with an above-the-knee amputation hit a growth spurt where they grow several inches in a year. Their prosthetic leg would no longer be functional within a few months time.
There is also a dramatic difference in the cost of a prosthetic leg than there is in the cost of producing an arm. While dexterity is often the goal in an upper extremity, the load asked of our lower extremities day in and day out requires them to be durable in construction and reactive to a patient’s body weight. The differences between prosthetic legs and prosthetic arms do not stop there.
Prosthetic legs typically cost more to create than prosthetic arms. Not only are they larger, necessitating more materials, the weight-bearing nature of the knee means that the mechanism that replaces it must be sophisticated enough to move while walking but lightweight enough to be carried by the residual limb. The most basic prosthetic leg will cost around $5,000 while myoelectric limbs that react to a patient’s muscle movement can cost as much as $50,000.
Fun Facts about Prosthetic Legs
- It is estimated that one in every 200 people has some form of limb loss.
- The average prosthetic leg lasts three to five years when working consistently.
- Below-knee amputation is the most common type of surgery that requires a prosthetic leg.
- Most prosthetics are made from carbon fiber, aluminum, and titanium parts. With the advent of myoelectric limbs, prosthetic legs are closer than ever to becoming “bionic body parts.”
- Prosthetic legs are custom fitted to each patient and can be designed to match a person’s lifestyle, weight, age, and health status.
- Most patients wear a compression sock that prevents their residual limb from swelling when their prosthetic is not on their body.
- There are multiple ways to hold a prosthetic leg on the body. Locking sockets, elevated vacuum, and suction are the most popular.
- Most prosthetic legs require the patient to wear a silicone gel liner that cushions the limb when they walk.
- Patients can commonly be fitted for a prosthetic leg two to six months after amputation surgery, depending on how quickly a person heals.
- Many patients report a phantom limb sensation, meaning they still feel like the missing limb is attached to their body.
Types of Prosthetic Legs
Prosthetic legs not only vary in where they are placed on the body, but they also vary by form and function. From basic legs to running blades, prosthetic legs are as varied as the people who wear them. However, prosthetic legs are often defined where the amputation has happened relative to the knee. Why?
Of all of the components in a prosthetic leg, the knee is the most complex. This is largely due to the knee being the most complex joint in the human body. Not only do we require it to help us bend, lift, stretch, run, walk, stand, sit, balance, and ride a bicycle, they do it with a series of tendons, bones, ligaments, soft tissues, and muscles. To mimic this in mechanical form is not as easy as configuring a series of hinges. Prosthetic knees must be able to lock when the wearer stands and move when they walk without any interference. Even though there are more than 100 mechanical knees available, they can be divided into two categories – mechanical and computerized.
- Mechanical knees can be further divided into single axis, poly-centric or multi-axis knees. Single axis knees are by far the simplest and least expensive option, but require the patient to use their body weight to hold them stable when standing. To compensate for this, most single axis knees have a locking mechanism that keeps them from swinging forward too quickly with every step. Polycentric knees (also known as four-bar knees) have multiple axes of rotation that better mimic the movement of the human knee. While they are heavier than their single axis counterparts, they can effectively shorten the leg during walking to prevent stumbling and are ideal for bilateral amputations.
- Computerized knees are relatively new in the advancement of prosthetic legs. Sensors detect movement and timing then adjust fluid inside of the knee according to the demand. With less physical effort required to walk, computerized knees offer a more natural gait to the patient with an above-the-knee amputation. However, they are not widely available, and their expense is often a deterrent to patients.
Prosthetic knees also need some form of motion control for a patient to walk while using them. Constant friction knee systems are simple and lightweight, but they only provide the wearer with a single walking speed. Variable friction knees allow for more variability in the cadence a person walks, but their moving parts tend to wear quickly, and they must constantly be adjusted for the patient’s needs.
Prosthetic knees also need some form of swing to maintain a normal gait. Some prefer a knee joint that locks in place and can be unlocked voluntarily. This stable knee makes it possible to walk without the lock engaged and is ideal for patients who are unstable or active patients who regularly hike or walk on variable terrain. Others prefer stance-control knees that are stable while standing but move when weight is displaced. These knees are great for older, less active amputees or as a first prosthesis.
That being said, it is easy to see why the knee is the most difficult joint to replace in the body and why prosthetic legs are commonly defined by their location relative to the knee.
Above the Knee Prostheses
Amputation to any level above the knee requires an above the knee (AK) prosthesis. Depending on where the amputation occurs, an AK prosthesis will include a socket, some form of prosthetic knee, a pylon, and foot. Some may even include a harness or suspension sleeve if the amputation occurs closer to the hip. These prostheses are fitted the same as any other, except most require adjustments both in the way the leg fits and the way the knee works. Over time, patients may discover that their activity level requires a different AK prosthesis for different activities (like running, hiking or biking).
Below Knee Prostheses
When possible, surgeons prefer to remove diseased or damaged legs below the knee to preserve leg function. In some cases, those with diseased or damaged lower legs function better with a below knee prosthesis than they do with damaged limbs. Without the complication of a mechanical knee, below knee prostheses are easier to fit a patient and perform a similar function to human legs. Below knee prostheses include a socket, pylon and foot and are fitted similarly to other prostheses.
Prosthetic legs for running
While most prosthetists specialize in human patients, prosthetic legs are not just for humans. Pets who have been through amputations are regaining their quality of life through prosthetic limbs. Even animals who would normally have died in the wild are getting a second chance at living with prosthetics.
Picture Perfect Prosthetics
Viktoria Modesta began modeling at the age of 15. Within a short time she became known for her striking beauty. But Viktoria spent the majority of her childhood in and out of hospitals. In 2007, at the age of 20, she chose to have her left leg amputated below the knee in order to safeguard her health and regain her mobility. With a background in performing arts, Viktoria turned her attention to the music world collaborating with some of the UK’s biggest producers. It wasn’t until she was branded as the “world’s first bionic pop artist” that her career began to gain traction. In 2015 she was signed with one of the largest modeling agencies in the world and became known for pictures where her prosthetic leg is featured prominently in unusual ways.
You never know how much you rely on your arms and hands until you lose one. Imagine not being able to pick up a child, brush your hair or teeth, hold a loved one’s hand or even make your bed. How do you control a smartphone, drive a car, cook a meal or type on the computer without the use of your arms? Fortunately, advances in prosthetic arms are improving the quality of life of millions of people worldwide.
Prosthetic Arm Facts
- 77 percent of all amputations are performed on males.
- It is estimated that 60 percent of all amputations (both of the arms and legs) are preventable.
- It takes about 20 hours to create a prosthetic limb.
- While prosthetic legs require prosthetic knees, the most complex joint in the human body, prosthetic arms require not only articulating elbows but the fine motor control that wrists and hands provide. As a result, arms are often more expensive to produce with the latest technology costing as much as $80,000.
- There are a variety of resources available to patients with prosthetic arms that help them care for themselves and their prosthesis.
While above-knee prosthetic legs are complicated due to the requirements we place on artificial knees to sit, stand, walk and run, above-elbow prosthetic arms are even more complicated to produce. Not only must the arm conform to the residual limb using custom fitted sockets, most require a harness for maximum stability and functionality. Then, the elbow and wrist don’t just move back and forth the way a knee does, they rotate as well for a full range of motion. Even then, only certain prosthetic elbows are equipped to carry weight. The most effective above-elbow prosthetics are myoelectrical prostheses. Designed to react to the muscles in the remaining limb, these arms are more than just cosmetic, they function the way anatomical arms do. Muscle signals can cause elbows to flex and extend. Hands can hold an egg without cracking it or drag a suitcase, wrists that can rotate to bring a book or paper into view are all possible with ME prostheses.
Advances in Prosthetic Arms
While myoelectrical prostheses are more readily available, scientists are continuously working toward an effective way to use the neurological function in residual arms to give patients prosthetic limbs with even more control. A series of sensors in the prosthetic, when mapped to the nerves in the arm, can move, not because of muscle movement, but because of thought. This allows a person more fine motor control than even myoelectrical prostheses can provide. But control is not the only advance in the way prosthetic arms are produced. What was once an expensive process is becoming more accessible through the evolution of 3D printing. Using images of a person’s residual limb, engineers can print custom-made plastic components for prostheses at a fraction of the price of their traditional counterparts. Combine advances in “reading” electrical signals from a patient’s residual limb and mapping capabilities of the nerves in the arm, and an inexpensive, bionic arm may be on the horizon.
That was exactly what one University of Central Florida engineering student set out to do when he saw the story of a young boy, born without an arm.