Chapman’s Orthopaedic Surgery
3rd Edition

CHAPTER 122
PRINCIPLES OF AMPUTEE PROSTHETICS
Patricia G. Rossbach
Michael A. Joyce
Eric Schaffer
Joseph M. Lane
P. G. Rossbach, M. A. Joyce, and E. Schaffer: The Joyce Center for Prosthetics and Rehabilitation, Manhasset, New York 11030.
J. M. Lane: Department of Orthopaedic Surgery, Weill Medical College of Cornell University; Metabolic Bone Disease Service, Hospital for Special Surgery, New York, New York 10021.
A prosthesis cannot come close to replacing a missing limb from either a functional or a cosmetic viewpoint. In the last decade, however, modern technology and improved materials have closed the gap considerably (1,3,4,11). The result is that motivated individuals with no additional health problems can now expect to regain a degree of function that will allow them to pursue an active life style of their choice. Limitation of the maximum performance possible should not be a consequence of either an inadequate prosthesis or negative expectations of the health care providers. Patients’ cooperation and positive attitude are critical.
To regain an active life style, patients must be educated about the operative procedure, receive psychosocial support, be fitted with a comfortable prosthesis, and engage in aggressive rehabilitation. Good communication between members of the health care team and patients cannot be emphasized strongly enough. Encouragement and positive reinforcement go a long way toward helping patients achieve their goals (see Chapter 120 and Chapter 121 for discussion of the principles of lower- and upper-extremity amputations, respectively).
LOWER-EXTREMITY AMPUTATIONS
AMPUTATION SITE VERSUS FUNCTION
Some of the older rules for limb length no longer apply in determining the level of amputation for prosthetic fit (12,13,17). For instance, when a lower-limb prosthesis is fitted, adequate length of the residual limb plus modern
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components can often result in significantly better function than an amputation that results in a longer lever arm with the use of more basic and primitive components (16,18).
Partial Foot Amputation
The main advantage of a partial foot amputation is the ability to walk without a prosthesis. The disadvantages at this site include the difficulty in making a cosmetic prosthesis with “toe off” function, the uneven gait that results without toe-off function, the tendency to develop an equinovarus deformity in the residual foot stump, and the limited foot components available (Fig. 122.1).
Figure 122.1. A: Midfoot amputation with a shoe insert prosthesis. B: An ankle–foot prosthesis for amputations through the hindfoot other than a Syme’s amputation. (From Dee R, Mango E, Hurst LC. Principles of Orthopaedic Practice. New York: McGraw-Hill, 1989:365, with permission.)
Syme’s Amputation
Syme’s amputation retains the heel pad. The advantage of this technique is that limited ambulation is possible without a prosthesis. Its disadvantages include a less cosmetic prosthesis due to the thick ankle required to accommodate the stump, the limited foot components available, and the limited amount of energy storage within these components (Fig. 122.2).
Figure 122.2. Syme’s prosthesis with posterior cutout for donning the prosthesis. (Courtesy of the Joyce Center, Manhasset, NY.)
Transtibial Amputation
In elective surgery where the amputation site can be selected, it is preferable to have enough space distally to incorporate appropriate prosthetic components for best function and cosmesis, while maintaining adequate length of the residual limb. Ideally, the length of tibia from the mid-knee joint to the distal end should be no less than 4 in. (10 cm) and no more than 7 in. (17.75 cm). If the tibia is too long, the choice of components is limited and cosmesis may be compromised. The space from the floor to the end of the residual limb (after the incision is closed) should be at least 12 in. (30.5 cm), but not if it will leave the length of the tibia less than 4 in. (10 cm).
Through-the-knee Amputation
Through-the-knee amputation provides the potential of end bearing in the prosthesis, a long lever arm, and condylar suspension. A knee disarticulation is particularly good for patients with poor gait and neuromuscular control. It is important in children with growth potential who need their distal femoral epiphysis to retain stump length. The disadvantages of this technique include the limited knee components available (including a button rotator), the differences in the center of rotation of the two knees, poor cosmesis due to the large femoral condyles, and atrophy of the thigh that occurs with condylar suspension. High-performance function is better achieved with a long transfemoral
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amputation and a prosthesis with modern knee components.
Transfemoral Amputation
When there is a choice of amputation site, a space of 4 in. (10 cm) from the knee center to the distal end of the residual limb is optimum, as long as this is not greater than one-third the length of the femur. This space permits a greater choice of knee and other components, and function and cosmesis are improved (Fig. 122.3).
Figure 122.3. A transfemoral socket shows a valve hole and one-way valve for suction application. This is a transfemoral prosthesis with a button rotator, hydraulic swing-stance knee, and carbon-composite ankle–foot system with shock-absorbing pylon. (Courtesy of the Joyce Center, Manhasset, NY.)
Hip Disarticulation and Hemipelvectomy Amputation
Lightweight components and flexible buckets/sockets have improved comfort and reduced the workload of patients wearing these types of prostheses (Fig. 122.4).
Figure 122.4. Endoskeletal prosthesis with foam cover for a hip disarticulation. (Courtesy of the Joyce Center, Manhasset, NY.)
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PREPROSTHETIC CARE
The goals after surgery for lower-extremity amputations in which there is a residual limb are listed in Table 122.1. These can be achieved through one of several methods: an immediate postoperative prosthesis or serial wrapping of the residual limb with an elastic bandage or an elastic shrinker. The overall aim is to reduce postsurgical edema. This in turn reduces postsurgical pain, minimizes later phantom pain, increases circulation (therefore hastening healing), and prepares the operative site and residual limb for a preparatory prosthesis. Where possible, elevation of the affected limb can also help reduce edema, although this must be accompanied by immediate aggressive physical therapy to prevent contractures of the surrounding joints. When there is no residual limb, the postsurgical goals are fewer (Table 122.1). Methods to reduce postoperative edema and prevent breakdown of the incision in patients include turning the patient onto the sound side and early mobilization.
Table 122.1. Goals of Preprosthetic Care
IMMEDIATE POSTOPERATIVE PROSTHESIS
An immediate postoperative prosthesis (IPOP) is a specialized dressing covered by a plaster cast molded to provide
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weight-bearing areas to enable patients to ambulate as soon as it is practical. The IPOP incorporates an adapter into its distal end that has a removable pylon with a prosthetic foot attached.
An IPOP is intended to control edema, promote ambulation, and prevent flexion contractures, as well as to keep patients from “waking up without a leg.” The prosthetist applies a specially padded and molded cast in the operating room after the surgical dressings have been applied. The advantage of this technique is that the cast initially prevents postsurgical edema, promoting wound healing and reducing pain. The cast also protects the residual limb, prevents flexion contractures in the surrounding joints, and molds the residual limb while compression is maintained. The difficulties with this technique are that the cast loosens as soon as the edema subsides and the subsequent pistoning action can cause tissue breakdown. The cast must either be continually replaced or be removable so that additional socks or fillers can be used to maintain compression. Other difficulties involve the heaviness of the cast, which prevents movement of the contained joints, impedes walking, and leads to muscle atrophy. The cast must be removed to monitor wound healing, frequently needs to be reapplied to contain compression, and is not cosmetic. Auxiliary suspension may be required (Fig. 122.5).
Figure 122.5. IPOP after a below-knee amputation. Surgical dressings are applied first. The prosthetist then rolls a stump sock into place, pads the end of the stump and bony prominences with specially designed cushioning materials, and applies a well molded plaster cast that incorporates the knee, with a hole left for the patella, and extends up to the mid thigh. This is held in place by a suspension strap hooked to the stump sock and tied to a band around the waist. A connection for a pylon is incorporated into the end of the cast. The pylon is applied postoperatively when the patient is ready to be mobilized. (From Fulford GE, Hall MJ. Amputation and Prostheses. Philadelphia: Williams & Wilkins Co.: 14, with permission.)
The advantage of an elastic compression bandage is that it can be reapplied whenever it becomes loose and therefore compression can be kept constant. Patients can be taught to wrap the limb, and compression can be applied only in areas where it is needed (Fig. 122.6 and Fig. 122.7). The problem with a compression dressing is that it may be wrapped too tightly, causing pain or tissue breakdown, or too loosely to be effective. Patients may have difficulty wrapping it themselves, and it may cause window edema when applied incorrectly or unevenly.
Figure 122.6. Figure-eight wrap for a transfemoral amputation. The wrap is applied around the stump and subsequently around the waist, progressing from distal to proximal. The dressing is gently wrapped to avoid overconstriction, and more compression is applied distally than proximally.
Figure 122.7. Figure-eight elastic wrap for a below-knee amputation. The wrap is applied, progressing from distal to proximal, with the pressure graduated so that more compression is provided distally. The bandage should not be applied too tightly.
Elastic shrinkers, when applied correctly, provide overall compression and allow wound monitoring. They may be difficult to apply correctly in some individuals, however, and may not put direct pressure over areas where it is needed (Fig. 122.8).
Figure 122.8. Elastic shrinker for a transfemoral residual limb. (Courtesy of the Joyce Center, Manhasset, NY.)
The choice of these various techniques depends on the ability and cooperation of a patient, the length of the limb, and careful evaluation of the goals for the individual.
Secondary goals include the maintenance of range of
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motion in the surrounding joints (hip and knee), prevention of muscle atrophy, and elimination of pain. To achieve these, physical and occupational therapy consisting of range-of-motion, stretching, and strengthening exercises should be initiated as soon as possible. An early fit of the prosthesis will be beneficial.
RATIONALE FOR A PREPARATORY PROSTHESIS
A preparatory prosthesis is fitted to a patient while the amputated limb undergoes normal maturational shape changes after surgery. Fitting should be started after the sutures or staples have been removed and the incision has healed.
In the lower limb, the primary purposes of a preparatory lower-extremity prosthesis include controlling postsurgical edema, minimizing the loss of muscle mass and strength, preventing joint contractures, and allowing patients to ambulate. Historically, preparatory prostheses were made with the simplest components, worn with prosthetic socks, and suspended with straps and belts. To accommodate postsurgical shrinkage and muscle atrophy of the residual limb, the ply of the socks was increased until the size of the limb stabilized, at which time the definitive prosthesis would be fabricated. However, new socket materials and designs, along with modern components and more aggressive training, promote the use of remaining muscle so that after postsurgical edema has subsided, there is often little or no muscle atrophy. If appropriate for an individual, one of several types of suction suspension can often be used as soon as the incision is completely healed, replacing the socks and belts. With the use of more sophisticated components, correct gait can be taught immediately to avoid retraining once the definitive prosthesis has been fit.
After the socket is carefully fitted and fabricated and the components are aligned, patients should be taught how to use the prosthesis. Limit ambulation to partial weight bearing, and check the residual limb frequently; graduate to total weight bearing as tolerated. How long this takes will depend on the fit of the prosthesis, as well as the strength, coordination, ability, and determination of the patient.
Although the residual limb will continue to mature and change shape for the lifetime of individuals, the most dramatic changes occur during the first 3–6 months. Constantly monitor and modify the socket, or change the sock ply to accommodate these changes to maintain fit. Make patients aware that this is quite normal. The definitive prosthesis is fabricated once these changes have stabilized.
PROSTHETIC FITTING AND ALIGNMENT
When fitting a first prosthesis, the prosthetic team thoroughly examines a patient and evaluates the medical history. A detailed explanation of the process of prosthetic fitting, preferably accompanied by written materials, is given to the patient. A prescription recommendation is sent to the referring physician by the prosthetist with a request for a letter of medical necessity. The primary concerns are comfort, function, and cosmesis. The prescription recommendations depend on the patient’s age, previous activity level, hoped-for outcome, length of residual limb, medical history, and reimbursement limitations. The prescription should include type of prosthesis (endoskeletal versus exoskeletal), type of suspension, socket design, materials, choice of components, and cosmetic finish.
The comfort of the socket is always the primary concern and depends on the skill of the person taking the measurements or the impression of the residual limb, as well as on the materials used. Initially, measurements are taken, and a negative wrap of the residual limb (or digitized equivalent; see below) is made. A positive model is produced from the impression and modified, and a clear diagnostic socket is formed over that mold. The diagnostic socket is fitted to the residual limb, the fit is checked, and any indicated changes are made to the positive model, with refitting of the socket if necessary. A flexible, total-contact socket is formed within a rigid frame, and the chosen components are aligned so that the foot, knee joint, and so on are in a neutral alignment. The prosthesis is then fitted and dynamically aligned, and initial gait training is performed while the alignment is fine-tuned. After the prosthesis is delivered to the patient for trial use, a protective cosmetic cover is fabricated, and further alignment and fitting changes are made, as necessary, on the basis of continued functional examination.
Although the majority of prosthetists take a cast of the residual limb and manually modify the positive mold to fabricate a socket, an alternative method is the computer-aided design/computer-aided manufacturing (CAD/CAM) system. With this system, information on the residual limb is converted into numerical data, read into the computer by a digitizer (usually from a negative mold), and converted into a three-dimensional image by commercially available software. Modifications to this image are made by the prosthetist; the information is then relayed to the attached carver, which produces the positive model. Thereafter, the processes are similar regardless of whether the manual or the CAD/CAM method is used: A hard, clear diagnostic socket is formed over the model and then fitted on the residual limb. Weight-bearing surfaces and bony or sensitive areas are checked, and any necessary modifications are made to the diagnostic socket before the definitive one is fabricated.
Once the components have been assembled and bench-aligned, a dynamic alignment must be done with the patient wearing the prosthesis. There are two schools of thought concerning alignment: According to one school, the prosthesis is aligned to accommodate any abnormalities in posture, such as flexion contracture, whereas with
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the second gradual corrections in alignment are made simultaneously with aggressive rehabilitation of the patient, until a more correct alignment can be obtained.
Frequent follow-up visits are necessary after delivery of the prosthesis to make the corrections and adjustments that will inevitably be needed as a patient progresses. It is important that patients understand that this is a normal process and that a plateau will eventually be reached where it will only be necessary to have routine check-ups, unless a new prosthesis needs to be fabricated. They must be informed of the importance of maintaining a stable body weight and a regular exercise program. Excessive gain or loss of weight compromises fit and function of a prosthesis. Many of today’s components are designed for a weight range or activity level.
Endoskeletal versus Exoskeletal Prostheses
A endoskeletal prosthesis is made with an internal skeleton of components and a foam outer cosmesis (Fig. 122.9). It is modular in design, thus permitting greater interchangeability. The advantages of the endoskeletal are that changes in alignment can be made with ease at any time during the life of the prosthesis to accommodate changes in posture, gait, or growth. In the modular design, individual components can be changed without remaking the prosthesis. The problems with this technique are that it is more expensive and may require more maintenance.
Figure 122.9. Endoskeletal type of prosthesis, without socket. A Flex-Foot, Inc. prosthetic foot has a shank component composed of carbon fiber epoxy. This prosthesis stores energy during the stance phase and returns it to the amputee for push-off. A foam cover will be added for cosmesis.
The exoskeletal prosthesis is often made of wood or polyurethane with a laminated rigid outer shell (Fig. 122.10). Once fabricated, it has limited adjustability without being refabricated. It is less expensive and has a more durable cover than the endoskeletal type. Its disadvantages include no postdelivery accommodation–alignment changes, limited dynamic response capability, and limited component choices. In addition, it is frequently heavier than the endoskeletal prosthesis.
Figure 122.10. Exoskeletal type of below-knee prosthesis. This patellar tendon–bearing type of below-knee prosthesis has a Pelite liner and supracondylar suspension. (From D’Astous J, ed. Orthotics and Prosthetics Digest. Canada: Edahl Productions Ltd., 1981:113 with permission.)
Suspension can be achieved with suction or a sleeve, belt, or cuff strap. The suction technique aims to reduce pistoning in the socket, thus requiring less energy expenditure during ambulation (Fig. 122.11). It promotes venous return and gives patients the feeling that the prosthesis is lighter. In addition, it eliminates the need for uncomfortable belts and straps.
Figure 122.11. Types of suspension for transtibial amputees. A: Traditional patellar tendon–bearing (PTB) total-contact socket with a silicone socket suspension system in which the suction unit attaches to the socket by a shuttle-lock system. If this is not used, a supracondylar suspension strap can be added. B: PTB supracondylar prosthesis. C: PTB supracondylar/suprapatellar socket. D: PTB prosthesis incorporating side hinges and joints with a thigh corset.
In the transfemoral amputation suction application, the residual limb is drawn into the socket with an elastic bandage or a type of pull sock until the air is displaced through the distal valve hole; a one-way valve is placed in the valve hole to prevent air from reentering the socket (Fig. 122.3).
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Although it seems easier to lubricate the residual limb and push it into the socket, the result is hammocking (stretching) of tissues on the distal end and failure to get all the proximal tissue into the socket.
In transfemoral or transtibial amputations, one of several silicone or gel liners with a distal locking mechanism can be used. These are rolled up onto the residual limb, with the liner holding onto it; and the distal locking mechanism attaches mechanically to the prosthesis, creating an alternative suction fit.
The sleeve technique is used for transtibial application. The distal end of the sleeve fits over the proximal portion of the prosthesis. The proximal end of the sleeve is then pulled up over the knee onto the patient’s thigh. It can act as a suction device if it is made of nonporous material.
The belt suspension is used in transfemoral and transtibial applications when suction suspension is not an option. It can be used in conjunction with a socket interface, socks, or silicone gel liner that has no locking mechanism.
The supracondylar cuff strap in used for transtibial applications when suction is not an option. It is sometimes used in conjunction with a waist belt.
Socket Design
The shape and fit of the socket is the single most important factor in a successful outcome. Today’s sockets are designed to fit more anatomically and to provide total contact with the residual limb. Increased suction on the distal end of the residual limb, due to lack of contact, results in verrucous hyperplasia, if left uncorrected. Under extreme circumstances, this can lead to localized infection or cellulitis.
The sockets are usually made of flexible plastic and surrounded by a rigid frame to support the weight-bearing areas. The quadrilateral socket for the transfemoral amputee is being replaced by one of several versions of ischium-containing designs. Containment of the ischium within this type of socket provides pelvic stability and promotes more normal femoral alignment and better function of the remaining intact musculature. Proprioception is also increased.
It is now possible to make more comfortable sockets for higher transfemoral, hip-disarticulation, or hemipelvectomy amputations. The bucket socket is made of laminated silicone or flexible plastic supported by a rigid frame (Fig. 122.4). The new families of silicone or gel socket liners have improved the comfort of sockets.
Choice of Components
Components that improve the comfort and function of the prosthesis should be used. It is our opinion that the more debilitated a patient is, the greater is the need for help from the prosthesis. The question posed should be, “What can we provide to make walking easier and more efficient for a person?” rather than making the assumption that this person is not “a candidate for ambulation.” The components requiring consideration are the hips, the knees, and the feet.
The hip joints are limited to single-axis joints with an extension assist.
Several types of knee joints are available. The single-axis,
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constant-friction knee is the simplest design. The main drawback for this component is that ambulation is normal only at one speed for a set amount of friction. The safety knee with constant friction is designed so that the patient’s weight locks the knee in the standing position. The polycentric knee joint has hinges external to the prosthesis and was originally designed for through-the-knee prostheses. It provides better control during standing and the stance phase of gait. The swing phase may be controlled mechanically or with a hydraulic cylinder. Hydraulic knee joints, which are the most sophisticated on the market to date, control both swing and stance phase and are velocity-sensitive. Table 122.2 specifies the indications for use of the various types of prostheses, together with advantages and disadvantages.
Table 122.2. Knee Joints for Above-Knee Prosthesis
The prosthetic ankle–foot systems comprise several main groups: articulated ankle joints, dynamic-response and energy-storing foot, and nondynamic-response and/or energy-storing feet. The simplest and cheapest combination is the nonarticulated ankle and the nondynamic-response foot, called the solid ankle-cushion heel (SACH) foot; it is also the least efficient.
The combination of a solid ankle and a dynamic-response foot allows maximum loading of the toe section of the foot during “rollover.” Similar to the action of a coiled spring, when the pressure or loading is removed, the toe section springs back to provide push-off. The most extreme version of this is found in a foot–ankle and shank made of carbon fibers, in which the loading action or energy storage is also carried out in the shank. The method of loading the toe must be taught, or the benefits will not be experienced. In fact, users may complain that the toe is too stiff, and reject the foot.
An articulated ankle joint, useful for people who spend considerable time walking on uneven ground, is heavier than other prosthetic feet and requires more maintenance. An added disadvantage is that even if it is combined with a dynamic-response foot, the action of the ankle precludes loading the toe to provide push-off. The various options for lower-extremity prosthetic components are shown in Figure 122.12.
Figure 122.12. Choice of components for the transfemoral amputee. (From Braddon RL. Physical Medicine and Rehabilitation. Philadelphia: W.B. Saunders, 1996:307, with permission, University of Texas Health Science Center at San Antonio.)
REHABILITATION AND TRAINING
A successful outcome depends as much on rehabilitation and training as it does on the fabrication and fitting of a prosthesis. Studies show that energy expenditure during ambulation is higher for amputees than for nonamputees (2,6,7,9,10,14,15,19).
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Factors affecting energy expenditure include the length of the residual limb, unilateral or bilateral amputation, the reason for amputation, the choice of prosthetic components, the weight of the prosthesis and whether the weight is concentrated distally or proximally, the efficiency of the suspension aids for the prosthesis, the symmetry of the gait, the state of the cardiovascular system, the patient’s age, and the general state of physical fitness (5,11).
The net energy cost of ambulation, or the amount of oxygen required per kilogram of body weight per meter walked (ml O2/kg/m), is higher than normal in most untrained amputees and increases as the amputation level gets higher. In addition, the preferred speed of walking becomes slower (8). The weight of the prosthesis can contribute to this increased energy cost, particularly if the extra weight is distal. Suction suspension can make a prosthesis feel lighter, while pistoning between residual limb and socket creates a pendulum effect. Careful choice of components is therefore very important. A less symmetric gait also requires more energy. Elderly individuals who have an amputation for vascular reasons are less efficient partly because of the aging process but also as a result of arteriosclerotic heart disease, peripheral vascular disease, or diabetes, which all inhibit the efficient transfer of oxygen to the muscles.
Start balancing, stretching, and muscle-strengthening exercises as soon as possible after amputation to maintain flexibility, prevent flexion contractures, and preserve muscle strength and mass. In addition, make an aerobic conditioning program a part of the rehabilitation process whenever possible. This combination will have the dual effect
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of strengthening the cardiovascular system so that there is more efficient transfer of oxygen and building up muscles to use that oxygen (8). Once a prosthesis has been fitted, patients should do all physical therapy and exercise programs with the prosthesis on.
Correct-gait training starts with the first step taken in the prosthesis. Even if only partial weight bearing is allowed, encourage amputees to stand up straight and take even strides. It is easier to teach someone correctly from the beginning than to try to correct a bad habit later, just as it is easier to prevent a flexion contracture than to correct it. Although walking frames are frequently used, particularly by the elderly, they have the disadvantage of encouraging users to walk unevenly. Typically, a long step is taken with the sound side to the front of the frame, and the prosthetic side is then only brought even with the sound side. If a walker must be used for stability, it should be moved forward before each footstep to allow room for the feet to be placed sequentially one in front of the other.
Fear of losing balance and falling is the main concern of new amputees. Functional muscle-strengthening exercises—those that are carried out standing on the prosthetic side while exercising the sound side—are as important as exercises carried out on the affected side.
We have observed that, unless taught otherwise, many amputees will stand and walk with their affected-side hip behind their sound-side hip, even though the shoulders will remain straight. The result is that the stride length is uneven, with the stride taken with the prosthesis being longer than that with the sound side. Use of an energy-storing/dynamic-response foot will in effect prevent loading of the toe and the resulting toe push-off. It has therefore been our practice to gait-train our clients in the following way:
  • At heel strike on the affected side, contract the muscles on that side from the gluteals to the end of the residual limb and push down and back.
  • Move the affected hip forward until the foot is flat on the floor while rolling forward (not up) onto the toe of the sound side and starting the sound-side swing phase.
  • Move the affected hip farther forward, feeling the stretch in the hip flexors, compressing and loading the prosthetic toe while completing the swing phase of the sound side.
  • At heel strike on the sound side, relax the muscles on the affected side. The prosthetic toe will push off, initiating a knee bend and affected-side swing-through.
In this way, the patient’s own body weight is doing the work of loading the prosthetic toe. It is also important to maintain normal upper-body movement, that is, equal arm swing and torso rotation. Although it seems to be very difficult work initially, the result is a more even gait pattern and less work. Figure 122.13 and Figure 122.14 depict the appropriate activity of the muscles during gait for transtibial or transfemoral amputation.
Figure 122.13. Muscle activity in the flexors and extensors of the hip and knee during the gait cycle for a transtibial amputee.
Figure 122.14. Muscle activity flexors and extensors of the hip in a transfemoral amputee during the full-gait cycle.
Unless contraindicated, a supervised aerobic conditioning program will improve the endurance of all lower-extremity amputees—it is not only for athletes. In our experience, as long as a prosthesis fits well, a tailored exercise program can be undertaken by individuals with diabetes and circulatory insufficiency, and they will benefit. Stationary bicycles, rowing machines, or upper-body ergometers can all be used, although the treadmill is the piece of equipment of choice because it also improves walking. Ideally, in addition to stretching and muscle-strengthening exercises, these individuals should exercise for a minimum of 20 minutes at least three times per week at an elevated heart rate determined by their physicians.
GAIT ANALYSIS
After a patient has had some early experience in the prosthesis, members of the prosthetic team must observe the patient’s gait on a straight-level walkway to be certain that gait abnormalities are not due to inadequate rehabilitation or improper fitting or alignment of the prosthesis. Table 122.3 and Table 122.4 provide an outline of commonly observed gait abnormalities, a description of their characteristics, and common causes that require correction.
Table 122.3. Gait Analysis of the Transtibial Amputee
Table 122.4. Gait Analysis of the Transfemoral Amputee
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UPPER-EXTREMITY AMPUTATIONS
AMPUTATION SITE VERSUS FUNCTION
Upper-extremity amputations include wrist disarticulation, below-elbow amputation, elbow disarticulation, above-elbow amputation, shoulder disarticulation, and forequarter amputation. Wrist disarticulation has the greatest range of extremity motion: flexion, extension, pronation, and supination. It also has a long lever arm for strength and support of distal components, and increased proprioception and function. However, it is more difficult to fit with a myoelectric hand and wrist, and the resulting fit is often longer than the sound side. The choice of components is limited.
The below-elbow amputation provides anatomic ability to pronate and supinate, has a wider range of components available, and can achieve equal length with the sound side. The choice of a myoelectric or body-powered prosthesis is available. This amputation has less range of motion, a shorter lever arm, and less proprioception and function than the wrist disarticulation. Anatomic pronation and supination decrease as the length of the residual limb decreases.
The elbow disarticulation has a long lever arm and potential increased prosthetic range of motion, for the shoulder-to-elbow portion, when fitted with a prosthesis, will
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be longer than the opposite extremity than with the above-elbow amputation. The increased length at the elbow is due to the components, but casual observers do not detect the discrepancy. Choice of elbow components is limited to body-powered devices.
The above-elbow amputation has a better choice of elbow components, either myoelectric or body-powered. It has a short lever arm to support distal components and a limited potential range of motion.
Shoulder disarticulation and forequarter amputation leave patients with significant disability. The shoulder disarticulation has a very limited range of motion, and the prosthesis is cumbersome and heavy. It is frequently used primarily for cosmesis. The forequarter amputation also has a limited range of motion. The prosthesis is even more cumbersome and heavy, and suspension is particularly difficult. The more distal the amputation in the upper extremity is, the more functional the outcome and the better the cosmesis will be.
PREPROSTHETIC CARE
The goals of preprosthetic care for upper-extremity amputations are the same as those for lower-extremity amputations (Table 122.1).
IMMEDIATE POSTOPERATIVE PROSTHESES
An IPOP applied to the upper-extremity controls postsurgical pain and edema, improving circulation through reduced edema. Patients benefit psychologically by “waking up with a hand and arm.”
In amputations with a residual limb, a preparatory upper-extremity prosthesis can protect the residual limb from injury, prevent and treat contractures in the contained joints, and initially mold the residual limb. Patients maintain some two-handed function and receive training in the use of a prosthesis. It also allows assessment of a patient’s motivation. It can be removed for wound care and helps maintain body symmetry. The IPOP is usually worn only for 2–6 weeks after surgery. It is body-powered rather than myoelectric, and because of its weight, it uses a terminal hook device rather than a hand.
Nonetheless, the plaster cast of the IPOP is heavy and prevents movements of contained joints, resulting in muscle atrophy. If the cast becomes loose, it can cause tissue breakdown, particularly if it is resting on the transradial area or other proximal joint. The cast is also prone to fall off, particularly with transhumeral amputations, unless auxiliary suspension is used. Use of a cast also prevents monitoring of the incision. Another problem with this technique is that the terminal hook device is not cosmetic. An IPOP cannot be applied over extensive skin grafting and is not useful on very short residual limbs.
The rationale for upper-extremity preparatory prostheses is the same as that for lower-extremity preparatory prostheses.
PROSTHETIC FITTING
Rejection of upper-extremity prostheses is more common than for lower-extremity prostheses, with rejection rates increasing the more proximal the amputation site is. If prosthetic fitting is not done early, the client can become so adept at doing tasks with one hand that a prosthesis may seem cumbersome and heavy.
Length, condition, strength, and range of motion of the residual limb are the determining factors in the choice of a prosthetic system. Personal preference and motivation also play a role.
Preservation of length of the residual limb in upper-extremity amputations is critical for maximum function. This differs from the principles for the lower-extremity, where components can be more functional and a long residual limb length is not always beneficial.
Upper-extremity prostheses involve several choices:
  • Passive, in which the position of the terminal device or more proximal components is changed with a contralateral hand
  • Body-powered, in which gross body movements activate cables for function
  • Myoelectric, which is battery-powered and computer-driven
  • Hybrid system, which is a combination of body-powered and myoelectric
Table 122.5 delineates the advantages and disadvantages of these various options.
Table 122.5. Advantages and Disadvantages of Various Upper-limb Prostheses
Passive Prosthesis
A passive prosthesis can be used for individuals who want nearly life-like cosmesis or who have a high-level amputation and want a lightweight arm for cosmetic reasons. Passive prostheses are lightweight and nonfunctional. Cost depends largely on cosmetic finish. Off-the-shelf cosmetic covers are relatively inexpensive, while nearly life-like silicone covers are expensive.
Body-powered Prosthesis
In a body-powered prosthesis, the components are controlled by gross body movements through a system of straps and a harness that also doubles as a suspension aid. Stainless steel cables are attached to the straps proximally and to parts of the terminal device distally. If the amputation is proximal to the elbow joint, the cable will go through an elbow flexion attachment first. Body movements, such as a shoulder shrug or scapular abduction, put tension on a cable, causing a response. A series of movements initiates flexion, extension, and locking of the elbow, after which the terminal device can be activated (Table 122.6). If distal, the cables merely control the terminal
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device. The body-powered prosthesis does not depend on a battery for power, has a quicker component reaction time, and is less expensive than the myoelectric. There is feedback from the cable, and it is more durable and easier to maintain. Conversely, a body-powered prosthesis is at risk for repetitive injury of the activating muscles and joints, has limited pinch-force control for an involuntary terminal device, and can cause irritation to the skin of the contralateral side from the harness.
Table 122.6. Body Control Motions Typically Used for Prosthesis Activation
Myoelectric Prosthesis
Myolectric prosthetic components are controlled by voluntary muscle action via an electronic signal. The signal is picked up and amplified by electrodes placed over the muscle fibers and then downloaded to a computer to provide a specific function.
To determine whether a patient is a candidate for this type of prosthesis, myoelectric testing is done, before the components are chosen, to determine the maximum threshold available from the muscles. A myoelectric prosthesis provides good cosmesis and does not require a harness to be activated. It has increased range of motion and avoids repetitive-movement injury; it also has increased anatomic function and voluntary wrist rotation. To its disadvantage, a myoelectric device has a slower response time and increased weight distally, as well as higher maintenance. It is battery-dependent and less durable and has a longer down time for repairs. In addition, myoelectric devices are expensive, require longer training, and are less adaptive and not waterproof (Fig. 122.15).
Figure 122.15. Myoelectric prosthesis with a hand attachment shows a battery and electrodes (no socket). (Courtesy of Liberty Technology, Hopkinton, MA.)
Hybrid System
The hybrid system has a combination of body-powered and myoelectric components, such as a body-powered elbow and a myoelectric hand. This combination reduces the weight of the prosthesis and the expense.
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Choice of Components
Types of Suspension
The socket design depends on the type of suspension used—suction, bony lock, or harness—and the socket fit.
Full-suction suspension is used for wrist disarticulation and above- or below-elbow amputations. It is more secure, provides greater proprioception, reduces harnessing, and enables pronation and supination where anatomically possible. With full-suction suspension, the prosthesis feels lighter. However, it is more difficult to put on, especially for bilateral amputees, and difficult to fit for short above- or below-elbow limbs. In addition, it may be more expensive than other choices. A suction liner can be used for above- and below-elbow prostheses. It is easier to put on than full suction but may cause skin irritation. However, it is not as secure as full suction and is more expensive.
Bony-lock suspension can be used with or without socks for wrist disarticulation and below-elbow prostheses. It is easy to put on and remove. Its disadvantages are that it can cause muscle atrophy and prevents pronation and supination in below-elbow amputees (8).
Harness suspension can be used for all upper-extremity prostheses. It is less expensive and more reliable than other suspensions, and the only choice for a shoulder disarticulation or forequarter amputation. The problem is that it is irritating to wear and is less cosmetic.
Terminal Devices
Apart from appearance, weight is a main factor to be considered in the choice of a terminal device. Hooks are lighter, have less of a pendulum effect, and are less tiring to use. One option is to use a hook for daily activities and to attach a hand whenever cosmesis is more important. The passive device is nonfunctional and for cosmesis only. Both the body-powered hook and body-powered hand are voluntary- or involuntary-closing devices. The myoelectric hand is battery-powered and computer-driven. It has specific adaptive equipment, such as for sports, tools, and so forth.
The main groups of wrist units are body-powered and myoelectric. Myoelectric devices can pronate and supinate and are motor-driven. In elbow units, the main groups include passive, body-powered, and myoelectric devices. In shoulder units, there is only a manual unit.
Typical transhumeral and transradial body-powered prostheses are depicted in Figure 122.16 and Figure 122.17.
Figure 122.16. Typical body-powered prosthesis for a transhumeral amputee (harness not shown). (From D’Astous J, ed. Orthotics and Prosthetics Digest, Canada: Edahl Productions Ltd, 1981:153, with permission.)
Figure 122.17. Typical body-powered prosthesis for a transradial level amputee.
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REHABILITATION AND TRAINING
Institute occupational therapy as soon as possible to maintain body symmetry, prevent flexion contractures, reduce surgical edema, and prepare the residual limb for the prosthesis. Early fitting of a prosthesis and promotion of two-handed function reduce the rejection rate. Strengthening exercises help counteract the pendulum effect of the terminal device. In addition, if myoelectric components are used, patients may need exercises to improve their ability to contract and cocontract the muscles chosen for the electrode site. Computer programs are used to aid in training patients. Activities of daily living must be taught before a patient becomes adept at doing these tasks single-handedly; otherwise the prosthesis may feel cumbersome.
For both upper- and lower-limb amputees, the resources necessary for success are not always available. Reimbursement issues continue to present considerable problems for both prosthesis and rehabilitation costs. In addition, a patient old enough to receive Medicare cannot learn to walk in the limited physical therapy sessions allowed for gait training at either outpatient or private physical therapy facilities. The reimbursement allowed by some insurance companies for one prosthesis per lifetime is not sufficient when the patient is a child born with a limb deficiency. Often, less functional components are used, purely on the basis of cost. In addition, prosthetists have different levels of skills.
PITFALLS AND COMPLICATIONS
SKIN PROBLEMS
Proper prosthetic fitting and a good training program to gradually accommodate amputees to their prosthesis and teach them how to care for it and their skin will avoid most skin problems. The residual limb and socket must be washed daily. Areas of split-thickness skin graft do not tolerate pressure, particularly if over bony prominences. They may eventually require revision if modification of the socket is not successful in preventing problems. Painful bursas can usually be managed by modifications of the socket, but occasionally problematic bony prominences will require removal.
Fungal skin infections are best avoided by cleanliness, keeping the socket and skin as dry as possible, and, when necessary, application of typical fungicides. Folliculitis usually results from sweating, poor hygiene, and pistoning in the socket caused by a poor fit. These problems usually respond to good skin care. If folliculitis progresses to abscess, it may require incision and drainage, with limited prosthesis use until healing occurs.
CHOKE SYNDROME
Proximal restriction in the socket with lack of total contact can lead to edema in the stump, which can lead to hemosiderin deposition and the eventual development of verrucous hyperplasia. This problem is preventable through good prosthetic fitting that achieves total contact in the socket.
PAIN
Pain over surgical scars or bony prominences or from neuromas should initially be addressed with socket modifications. If modifications are unsuccessful, then surgical intervention may be required (see Chapter 120 and Chapter 121). Nearly all adult amputees have an image and sensation of the amputated part known as “phantom sensation,” which usually declines with time. On occasion, this will be accompanied by pain in the phantom. Rule out any prosthetic or surgical causes of pain, as these may aggravate phantom pain. Referral to a pain management center for medicinal therapy, transcutaneous electrical stimulation, lumbar sympathic blocks, and other such interventions may be useful. Strong psychosocial support for patients is important.
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CONTRACTURES
It is important to emphasize to patients the critical role of early rehabilitation and exercises to build strength and prevent flexion contractures. Minor contractures of up to 10° can usually be accommodated in the prosthesis and require no special treatment. Hip and knee flexion contractures greater than 25° interfere with prosthesis fitting and will result in an unfavorable posture and gait pattern. Surgical release is sometimes necessary if these do not respond to nonoperative treatment.
PSYCHOSOCIAL MALADJUSTMENT
Amputee support groups and peer counseling are very helpful for patients sustaining amputations in accepting their new body image and adjusting to their new situation. Open discussion of their problems and concerns in a group or mentor setting is helpful.
RESOURCES
The Amputee Coalition of America and National Limb Loss Information Center (toll-free: 1-888-AMP-KNOW) is a national organization that is helpful for new amputees. This center has an information hotline and can help find a local support group and peer visitor, as well as providing appropriate pamphlets, magazines, and videos and a list of certified prosthetists in their area.
To be certified by The American Board for Certification in Prosthetics and Orthotics, Inc., today’s prosthetists must meet certain educational and professional standards. These include a bachelor’s degree and supervised internship, as well as passing a national certification examination followed by mandatory continuing education. As a result of constantly changing technology, better outcomes can be realized when prosthetists have input into the prescription request based on the initial prosthetic evaluation.
REFERENCES
Each reference is categorized according to the following scheme: *, classic article; #, review article; !, basic research article; and +, clinical results/outcome study.
# 1. Braddon RL. Physical Medicine and Rehabilitation. Philadelphia: WB Saunders, 1996:284.
+ 2. Cammisa FP, Glasser DB, Otis JC, et al. The Van Nes Tibial Rotationplasty: A Functionally Viable Reconstructive Procedure in Children Who Have a Tumor of the Distal End of the Femur. J Bone Joint Surg Am 1990:72:541.
# 3. Dee R, Mango E, Hurst LC. Principles of Orthopaedic Practice. New York: McGraw-Hill, 1989.
# 4. DeLisa JA, Gans BM. Rehabilitation Medicine: Principles and Practice, 3rd ed. Philadelphia: Lippincott–Raven Publishers, 1998.
+ 5. English Rd, Hubbard WA, McElroy GK. Establishment of Consistent Gait after Fitting of New Components. J Rehabil Res Dev 1995;32:32.
+ 6. Harris IE, Leff AR, Gitelis S, Simona MA. Function after Amputation, Arthrodesis, or Arthroplasty for Tumors about the Knee. J Bone Joint Surg Am 1990;72:1477.
+ 7. Herbert LM, Engsberg JR, Tedford KG, Grimston SK. A Comparison of Oxygen Consumption during Walking between Children with and without Below-knee Amputations. Phys Ther 1994;74:943.
+ 8. Lane JM, Kroll MA, Rossbach PG. New Advances and Concepts in Amputee Management after Treatment for Bone and Soft Tissue Sarcomas. Clin Orthop 1990;256:22.
+ 9. McClenaghan BA, Krajbich JI, Pirone AM, et al. Comparative Assessment of Gain after Limb-salvage Procedures. J Bone Joint Surg Am 1989;71:1178.
+ 10. Otis JC, Lane JM, Kroll MA. Energy Cost during Gain in Osteosarcoma Patients after Resection and Knee Replacement and after Above-the-knee Amputation. J Bone Joint Surg Am 1985;67:606.
# 11. Pinzur MS. Current Concepts: Amputation Surgery in Peripheral Vascular Disease. Instr Course Lect 1997;46:501.
# 12. Rodriguez RP. Amputation Surgery and Prostheses. Orthop Clin North Am 1996;27:525.
+ 13. Steen Jensen J, Mandrup-Poulsen T. Success Rate of Prosthetic Fitting after Major Amputations of the Lower Limb. Prosthet Orthot Int 1983;7:119.
+ 14. Torburn L, Powers CM, Guiterrez R, Perry J. Energy Expenditure during Ambulation in Dysvascular and Traumatic Below-knee Amputation: A Comparison of Five Prosthetic Feet. J Rehabil Res Dev 1995;32:111.
+ 15. Traugh GH, Corcoran PJ, Reyes RL. Energy Expenditure of Ambulation in Patients with Above-knee Amputations. Arch Phys Med Rehabil 1975;56:67.
+ 16. van der Windt DA, Pieterson I, van der Eijken JW, et al. Energy Expenditure during Walking in Subjects with Tibial Rotationplasty, Above-knee Amputation, or Hip Disarticulation. Arch Phys Med Rehabil 1992;73:1174.
+ 17. Volpicelli LJ, Chambers RB, Wagner FW Jr. Amputation Levels of Bilateral Lower-extremity Amputees: Analysis of One Hundred and Three Cases. J Bone Joint Surg Am 1983;65:599.
! 18. Waters RL, Perry J, Antonelli D, Hislop H. Energy Cost of Walking of Amputees: The Influence of Level of Amputation. J Bone Joint Surg Am 1976;58:42.
+ 19. Zohman GL, Boardman DL, Eckardt JJ, Lane JM. Stride Analysis after Proximal Tibial Replacement. Clin Orthop 1997;339:180.