Upper Extremity Prosthetics
Upper limb amputations tend to be less common than lower limb amputations, but can affect people of all ages. There are approximately 10,000 new upper extremity amputations in the United States every year.
The most common causes of upper limb amputations are
- Trauma such as motor vehicle accident, machinery accident, gunshot wound
- Infection or burns
- Tumors or disease
- Conditions present at birth
An upper extremity amputee has a variety of prosthetic options. Listed below are the different types available.
Passive Functional / Cosmetic
A Passive Functional or Cosmetic upper extremity prosthetic device is similar in appearance to the non-affected arm or hand and replaces what was lost. It provides simple aid in balancing and carrying. The advantages of this type of prosthesis is that they can be cosmetically appealing; lightweight; simple to use; there is little maintenance; they are great for partial hands and provides opposition.
Body Powered / Conventional
A Body Powered or Conventional upper extremity prosthetic systems use a harness with cables to move the prosthesis. By engaging larger muscles, the cables can open and close a hook or hand, as well as an elbow or shoulder joint. The harness system is controlled by specific body movements. The advantages of a conventional prosthesis is that the heavy duty construction of the device gives it a long life; it offers proprioception; it’s less expensive and lighter in weight than myoelectric devices; and there is a reduced cost and maintenance.
Myoelectric / External Power
With myoelectric systems, the prosthesis actually takes advantage of the natural signals that your muscles generate when they are used. Small sensors, known as electrodes, measure and amplify these muscle (or ‘myoelectric’) signals and are used to activate various functions of the prosthesis, such as opening or closing the hand. Batteries are used to power the motors that make these movements. Myoelectric prostheses typically do not involve elaborate harnesses or cables and rely on very subtle muscle movements. This frees the user to be able to perform more complicated fine motor skills while still operating the prosthesis. The user also has control of grip strength and speed. These systems offer functional cosmetic restoration. There are many different types of myoelectric prostheses and there are various manufacturers that produce these devices.
A Hybrid upper extremity prosthetic device combines the use of body power and external power. Hybrid systems take advantage of both systems. A hybrid system may have a myoelectrically controlled hand and wrist, with a body-powered elbow joint. The advantages of this system is that there is a greater functional envelope from the basic body powered device; it offers reduced weight from the myoelectric device; it offers the greater grip force like the myoelectric; the harness system is reduced; and the initial costs and maintenance costs are reduced.
Adaptive / Recreational
A Recreational or Adaptive upper extremity prosthetic device is customized for a specific function or recreational activity. There are various adaptive devices available for activities such as skiing, golf, fishing, construction work, shooting pool, playing guitar and so much more.
Upper Extremity Prosthetic Fitting
You’ll be fit with your new prosthesis once your residual limb has healed and has stabilized in its size. This usually takes from four to six weeks after the surgery.
During your first fitting visit with your prosthetic team, they will make a cast of your residual limb with plaster so that they have an exact replica of your limb. This will be used to make a test socket. The test socket is an interim socket that allows your team to customize the fit of your prosthesis and is generally made from a clear thermoplastic. The material is easily reformed to get an intimate fit, and, because it is transparent, shows where your skin is coming in contact with the socket.
Socket fit is very important. Once the socket has been customized for your unique anatomy, a definitive socket will be fabricated, from lightweight thermoplastic or carbon fiber. The prosthetic components are then attached to this socket.
Training to use your prosthesis
The goal of rehabilitation training with a physical therapist is to help you gain as much mobility and independence as possible.
Your therapist will help you learn how to use and care for your prosthesis properly, including how to put the prosthesis on and taking it off. Then you’ll begin controls training, repetitive drills, and finally, Activities of Daily Living (ADLs).
- Controls Training – Depending on the components used in your prosthesis, controls training will teach you how to open and close your terminal device or hand, rotate it internally and externally, and, in case of higher level amputations, how to flex or extend the elbow and shoulder.
- Repetitive Drills – You’ll practice making specific movement patterns. The more you practice the better you’ll get at remaining relaxed while performing the movements, and the more automated the movements will become. With enough repetition, you’ll be able to simply make a movement, instead of thinking about it. Suitable exercise accessories include cones, various peg board games or a pinch tree with individual pegs which are changed in their vertical or horizontal positions. This means you have to purposefully rotate and grip with your prosthetic hand.
- Activities of Daily Living (ADLs) and Everyday Training – After the repetitive drills, you’ll be ready for more complex movements that you’ll encounter in everyday life. Your therapist may tailor this training you your personal goals and needs, depending on your day-to-day life and occupation. You may begin with simpler activities such as folding a towel, and then work your way up to things such as preparing a complete meal and eating it with a knife and fork. ADL training may also include getting dressed and undressed; opening a bottle and pouring a drink; and using a computer and office tools.
Putting on and taking off your prosthesis
Correctly putting your prosthesis on (donning) and taking it off (doffing) by yourself is an important everyday task. Your family or friends may need to help you initially, but the goal is for you to ultimately be able to do this on your own. There are different ways to put your prosthesis depending on the type of prosthesis you have and the condition of your residual limb. Your therapist will show you which ones are suitable for you.
Caring for your prosthesis
Your prosthesis needs to be cleaned regularly. Wipe the inside of the socket with a moist cloth to remove sweat residue and skin particles. Keeping the contact surfaces with the skin clean helps to avoid skin irritation. If you wear a liner, please care for it daily according to the user manual. Finally, if you have a myoelectric system, you’ll likely have to charge the batteries daily.