Health

How much is a prosthesis and who pays for it?

The cost of a prosthesis can be significant. Some above-knee amputee prostheses can be a few thousand to more than $20,000. Parts of the prosthesis, such as a high performance foot or knee alone, can cost several thousand dollars.

For those covered by the program, Medicare usually pays for 80 percent of the prosthesis while the individual may be responsible for the other 20 percent. Ideally, the new amputee will have a secondary insurance that will pick up the rest of the cost. Some insurance companies may require pre-approval before a person can get his prosthesis made. Unfortunately, some insurance companies will only pay for one prosthesis over the course of a person’s lifetime. This can be a problem since a prosthesis can wear out in 3-5 years and need to be replaced. For these reasons, it is important that the amputee have a discussion with a prosthetist to determine which would be the most appropriate, practical prosthesis for his own needs.

How does one learn to use the initial temporary prosthesis

During the rehabilitation process, education regarding the proper donning and doffing of the prosthesis should be performed. Additionally, the amputee as well as the caregivers must be made aware of the limitations, challenges and safety risks that wearing a prosthesis can bring. If the amputee has other disabilities, adaptive equipment or other modifications to the prosthesis may need to be used. The skin should be checked every two hours when the amputee first starts to wear a new prosthesis as well as doing a careful skin check each time it is taken off. The skin at the end of the residual limb should not have any redness that lasts for more than five minutes. If there is no redness present, then the prosthesis can be worn an additional two hours each day. These are generalizations and the wear time is determined by the rehabilitation team and the overall health of the amputee.

The amputee first tries to use the initial temporary prosthesis while trying to walk between parallel bars. Parallel bars help with balance and allow the amputee to put most of his weight on upper limbs, alleviating pressure off the amputated limb. As the amputee walks, the prosthetist can make the necessary adjustments that make the prosthesis more comfortable and more efficient for walking. Meanwhile, a physical therapist can show the new amputee how to shift his weight appropriately while advancing the prosthetic limb.

Patients with any type of above-knee amputations usually require more training compared to below-knee amputees, because they usually need to become accustomed to using a knee that has been built into the prosthesis. Higher-limb amputees also have a more difficult time with balance and the amount of effort required to use a prosthetic limb.

Other training goals during the early rehabilitation phase with an initial prosthesis may consist of learning to negotiate steps (Figure 38 and 38a), ramps (Figure 39) and uneven terrain. Important safety techniques, such as how to rise off of the floor after a fall, should be practiced so that an amputee feels confident in his ability to do this (Figure 40).

Figure 38, 38a

Figure 40 - How to get up from the floor after a fall
 

When can an amputee try his first prosthesis?

In many cases, a person with a typical lower limb amputation may try an IPOP as described above. If this type of prosthesis is not available or recommended, the first temporary prosthesis can be fitted within the first few weeks following surgery but this is extremely variable. Proper fitting is done when the sutures or staples are removed from the surgical wound and the person’s health is stable enough to try to use it. Swelling in the residual limb should be controlled before a prosthesis is fitted. If the residual limb continues to change in size then it makes it difficult for the residual limb to fit into the socket. Medical problems such as heart and kidney failure cause the limb to fluctuate in volume.

Individuals with below the knee deficiencies may benefit from a suspension device known as a supracondylar cuff. This device is sometimes referred to as a Patellar Tendon Bearing Supracondylar Cuff since most of the weight bearing of the residual limb occurs through the patellar tendon as well as through the inner knee. The patellar tendon is a soft tissue structure that runs from the knee cap or patella and inserts onto the upper shin and is able to withstand a significant amount of weight. This prosthesis is held onto the lower limb via cuffs that extend above the knee. There are two bony prominences above the knee joint called condyles which project out. The cuff of this socket hangs onto these condyles keeping the prosthesis suspended onto the lower limb, hence its name. Occasionally, added suspension is provided by using a Silesian or TES belt as described above.

Some amputees may also use a liner over their residual limb to help improve the contact between the limb and the prosthesis. Though the liner may also help control limb edema, this should not be its primary function. Occasionally, the liner may also have a pin placed into the end which then locks into an opening in the prosthesis, improving suspension from the deficient limb. When the prosthesis needs to be removed, a button near the locking mechanism is pushed releasing the pin from inside and freeing the limb from the prosthesis. This type of suspension device is referred to as a shuttle lock/pin suspension system and is well accepted because of its comfort, stability, ease of application and overall performance. The other advantage of using a liner is that they can often be doubled up to accommodate a smaller limb that is not quite ready to accommodate a prosthesis. Later, one of the liners can be removed enabling the prosthesis to fit as the residual limb matures. The shuttle pin system can be used for both upper and lower limb amputees.

How do age, mental capacity and other factors affect one’s ability to use a prosthesis?

Other medical problems such as dementia will also impact upon the amputee’s ability to use a prosthesis successfully. A person’s mental capacity is very important, because training involves remembering how to do things with the prosthesis. This becomes very difficult to do if the person is unable to remember what they were told at previous therapy sessions. Additionally, safety becomes an issue if the person believes he can use a prosthesis but really doesn’t remember key safety features that prevent falls. This may be a problem when the individual tries to go down stairs or get out of a chair without assistance.

People who are older and have amputations that are higher up on their leg may be less likely to be able to walk with prostheses. Unfortunately, with age the ability to use a prosthesis declines. For example, only about one-third of amputees use a prosthesis over the age of 65 and this number drops as the person ages. Reasons that may inhibit the use of a prosthesis include poor balance, poor residual limb skin integrity and limb contractures.

What is the skeleton part of the prosthesis?

Another component of a prosthesis is referred to as the skeleton. The skeleton is the actual material that the prosthesis is composed of wood, plastic or metal. The skeleton can either have an exoskeleton or endoskeleton (metal) design. An exoskeleton design usually has a hard outer cover that appears similar in color to the other sound limb. It is generally very durable and resistant to stains. It can be used to improve the cosmetic appearance of a prosthesis. In contrast, an endoskeleton design, also referred to as a modular design, has a different appearance. It usually has a plastic socket attached to a metallic pylon attached to a prosthetic knee and/or foot. This type of skeleton may be used as a trial or temporary prosthesis. A soft synthetic covering may be placed over the modular components or endoskeleton once permanent adjustments have been made. This serves to improve the appearance. Unfortunately, this covering may become easily stained by an active adult and may not be suitable for an amputee who has bowel and bladder issues. In many cases the synthetic cosmetic covering may hinder the functioning of the underlying components such as the knee joint. Therefore, some active amputees elect not to use any covering at all over the endoskeleton.

What are the types of knees available for an above-knee amputee?

There are various types of prosthetic knees available for individuals with above knee amputations. However, the knee used in the prosthesis depends on the activity level of the individual. One of the first knees used in a prosthesis is what is known as a manual locking knee . This simple type of knee is usually appropriate for the less active adult who may only use their prosthesis for a few steps or to do a simple pivot transfer.

The manual locking knee is a hinge type knee joint that remains locked while the new amputee learns how to stand and walk, but the knee can be unlocked by pushing a button or pulling a lever. This allows the knee to bend so that the amputee can sit down without having the prosthetic limb sticking out in front of them.

If the amputee is more of an active person, then a true mobile knee joint can be used. Typically, this knee is either a constant friction (single axis) knee or a stance control (weight-activated friction) knee. The constant friction knee works like a hinge and has a built in mechanism that slows the swinging of the prosthesis as the person walks. The stance control knee is typically used for amputees with very short residual limbs who may need more stability when they walk. This type of knee has a braking mechanism that prevents the knee joint from buckling when it bends too far. In this way the amputee has a built in anti-stumble mechanism. The disadvantage of both of these knees is that they do not allow the person to increase their walking speed so a different knee component will be needed if one wants to walk more quickly or run.

Another type of knee joint is a polycentric knee. The most common type of this knee has four bars that simulate the knee joint as it rotates during the normal walking motion and more closely mimics a true knee joint’s motion. This type of knee joint is often used in people with knee disarticulations or with very long residual limbs so that the axis of rotation more closely simulates that of a normal knee.

If a person walks quickly or runs, then a hydraulic or pneumatic knee joint may be used. This knee uses either pressurized fluid or air allowing the prosthetic limb to change speeds depending on the walking speed. These units are referred to as cadence or speed responsive. Occasionally, a polycentric knee joint can be combined with a cadence responsive knee, to make the prosthetic knee function as close to a real knee as possible. These pneumatic knees are unaffected by changes in temperature but faster walking amputees can occasionally overpower the pneumatic pressure control making them unacceptable. In contrast, hydraulic units can be affected by extreme changes in temperature. However, they allow for a greater range of walking and running speeds and are therefore more commonly prescribed. Although the hydraulic knee has a higher cost and is possibly heavier than other knees, newer technologies are improving both of these concerns.

What are basic components of a prosthesis that a below-knee amputee would use?

Individuals with below the knee deficiencies may benefit from a suspension device known as a supracondylar cuff. This device is sometimes referred to as a Patellar Tendon Bearing Supracondylar Cuff since most of the weight bearing of the residual limb occurs through the patellar tendon as well as through the inner knee. The patellar tendon is a soft tissue structure that runs from the knee cap or patella and inserts onto the upper shin and is able to withstand a significant amount of weight. This prosthesis is held onto the lower limb via cuffs that extend above the knee. There are two bony prominences above the knee joint called condyles which project out. The cuff of this socket hangs onto these condyles keeping the prosthesis suspended onto the lower limb, hence its name. Occasionally, added suspension is provided by using a Silesian or TES belt as described above.

Some amputees may also use a liner over their residual limb to help improve the contact between the limb and the prosthesis. Though the liner may also help control limb edema, this should not be its primary function. Occasionally, the liner may also have a pin placed into the end which then locks into an opening in the prosthesis, improving suspension from the deficient limb. When the prosthesis needs to be removed, a button near the locking mechanism is pushed releasing the pin from inside and freeing the limb from the prosthesis. This type of suspension device is referred to as a shuttle lock/pin suspension system and is well accepted because of its comfort, stability, ease of application and overall performance. The other advantage of using a liner is that they can often be doubled up to accommodate a smaller limb that is not quite ready to accommodate a prosthesis. Later, one of the liners can be removed enabling the prosthesis to fit as the residual limb matures. The shuttle pin system can be used for both upper and lower limb amputees.

What are the types of feet available for amputees?

There is a vast array of feet and ankles available for a lower limb amputee. Adults who are only missing a few toes may only require a soft toe filler in their shoes for comfort. However, those with a partially amputated foot may develop an abnormal posture to the foot called equinus. The term equinus foot means that the foot is pointed down and the amputee may develop problems when they start to try to walk on it. As one tries to push off on an equinus foot, the end of the foot may become sensitive and may even develop skin breakdown. For this reason, the rehabilitation team should show the amputee appropriate stretching exercises and splints to prevent this deformity from occurring. To assist in preventing this deformity, an appropriate prosthesis may incorporate an Ankle Foot Orthosis or AFO combined with some type of modified shoe. This type of partial foot prosthesis seems to be better tolerated than using a large amount of filler in the shoe.

A person with a Syme’s amputation or other lower limb amputee just at or above the ankle may be able to bear some weight through the residual limb but will obviously have a difference in the leg lengths. To accommodate for this difference, a Syme’s prosthesis may be tried. With this type of prosthesis, the residual limb slides into the back part of the prosthesis being held onto the knee with a supracondylar cuff. The drawback of this type of prosthesis is its appearance since the end of the prosthesis near the foot needs to bulge out in order to accommodate the ankle bones. This does not make the prosthesis appear like a normal leg. In addition, if the Syme’s prosthesis does not fit well, the bones of the ankle can get sensitive, making the prosthesis intolerable.

The type of foot used in a prosthesis can be quite variable. The foot is a vital component of the prosthesis, as its structure, composition and position can aid in knee stability as well as ease of walking. The optimal type of foot is really contingent on the activity level of the individual and the type of prosthesis being fit on the residual limb.

One of the most basic types of prosthetic feet available is known as a Solid Ankle Cushioned Heel or SACH foot. This foot does not have a mobile ankle joint but has a heel that comes in different degrees of firmness. Surprisingly, the firmness of the heel can affect the stability of the amputee’s knee joint as well as how fast weight is transferred onto the foot during walking. For example, a softer heel leads to the knee being more stable and is used more commonly in lighter individuals, whereas a firmer heel is used in heavier patients to slow the amount of weight transferred onto the foot. Unfortunately, the SACH foot is not a very dynamic foot in that it doesn’t have much resiliency. It doesn’t provide much push off or “spring” into the prosthetic leg when the limb is leaving the ground during the walking cycle. Other types of basic prosthetic feet include the single axis foot, multiple axis foot, Stationary Attachment Flexible Endoskeleton (SAFE) foot and Stored Energy (STEN) foot. Each of these feet have advantages and disadvantages, but in general are somewhat heavy and are used for adults with a lower activity level. However, they can accommodate different types of uneven ground and do not need a lot of maintenance.

In contrast to these types of feet, a dynamic or energy-storing foot stores and releases energy while the patient is walking. As the prosthetic limb accepts the weight of the individual the prosthetic foot compresses slightly. When the limb is advanced to take the next step, energy is released like a spring helping to propel the prosthetic limb forward. These types of feet may look real such as the SEATTLE LIGHT foot or CARBON COPY II FOOT or may appear somewhat unusual. Although these feet are lighter, more expensive and require more maintenance than some other prosthetic feet, they are best used in very active or athletic amputees. Once again the type of prosthetic foot used in a prosthesis varies depending on the individual case.