Chapter 34D - Atlas of Limb Prosthetics: Surgical, Prosthetic, and Rehabilitation Principles
Upper-Limb Deficiencies: Developmental Approach to Pediatric Upper-Limb Prosthetic Training
Joanna Grace Patton, B.S., O.T.R.
*This chapter is adapted from material presented in Comprehensive Management of the Upper Limb Amputee, published by Springer-Verlag. Chapters in that book by Joanna Grace Patton entitled "Developmental Approach to Pediatric Prosthetic Evaluation and Training" and "Upper-Limb Prosthetic Components for Children and Teenagers" are used as a basis for this format. The author wishes to express appreciation to Springer-Verlag for permission to use the selected content.
THE CHILD WITH A UNILATERAL TRANSVERSE FOREARM DEFICIENCY
Child Development-Foundation For Early Prosthetic Fitting and Treatment
Principles of child development are important as a foundation for evaluating, prescribing prostheses, and training children who have limb deficiencies or acquired amputations. The staff at the Child Amputee Prosthetics Project (CAPP) at both the University of California at Los Angeles and Shriners Hospital for Crippled Children, Los Angeles Unit, adhere to this philosophy of care. They feel that pediatric prosthetic treatment is not and should not be a duplication of adult treatment.
Sypniewski reviewed the literature in 1972 and reported on the various rationales for early upper-limb prosthetic fitting for children. Early fitting is clearly cited as an important concept. However, there is and always has been a difference of opinion about which developmental milestones are most appropriate as a basis for planning treatment. Clinicians still debate what is meant by "early fit." In a 1976 article by Fisher, she discussed both the definition and practice of early fitting. She cited research that supports the belief that the development of visually guided reaching is dependent on the opportunity to see the limb moving in space. She questioned whether fitting the baby before 3 or 4 months of age would aid visually guided reaching and thus influence future prosthetic wearing and use patterns.
These same questions concerning when to fit, what to fit, and how to do training will continue to have an impact on both health professionals and the general public in the 1990s. For example, the development of myoelectrically operated components for children in the 1970s and the manufacture of lightweight electric hands and miniature circuits are changing the prescription and training process. In selected centers that have well-established myoelectric programs, babies between 4 and 15 months of age are receiving their first myoelectric prosthesis. The approach has gained media attention and generated much interest and controversy among professionals and families who have limb-deficient children.
At CAPP, the first prosthesis with no active control is fit when the baby achieves independent sitting balance. Since the baby has progressed beyond the stage of rolling, the prosthesis is less likely to hamper movement. The practice at CAPP is based on clinical experience as well as a study by Brooks and Shaperman that identifies the developmental period prior to 2 years of age as a good time to fit the first prosthesis. In fact, children who received the prosthesis before the age of 2 years develop better wearing patterns and skills than do those children who received one between 2 and 5 years of age. Most clinicians agree that fitting the first prosthesis when the child is entering the "terrible twos" can be a very negative experience for everyone and should be avoided when possible.
Family's Introduction to the Prosthetic Program
Early intervention and support are most important for families. They are encouraged to see the clinic team as soon after the baby's birth as possible. Some parents are totally overwhelmed by the birth of their child with a limb deficiency, while others seem more able to cope with the birth crisis. The early opportunity to discuss feelings and concerns is most valuable to the family. They also need to receive appropriate information about the baby's limb deficiency and future treatment. Parents are asked to bring siblings and extended family members so that the CAPP staff may provide the following types of information:
- Reassure the family that the baby with a transverse forearm deficiency has the potential to develop normally unless there are other medical or neurologic problems unrelated to the limb deficiency.
- Explain that the child will be able to perform most activities of daily living, including self-help, school, recreational, vocational, avocational, and household tasks with or without a prosthesis. Skills will develop because of the child's natural abilities and interests.
- Reassure the family that the child should be treated the same as other siblings or children in terms of performing daily tasks, receiving discipline, and enrolling in regular school.
- Provide accurate information about prostheses, and clarify misconceptions about state-of-the-art technology. Explain how the child performs activities with and without a prosthesis.
Parents frequently ask whether a prosthesis has a real value. Certainly a child can use substitute grasp patterns like clasping an object under the arm or against the body with the residual limb. With the prosthesis, the child can hold the object away from the chest and at the midline of the body. Then he is able to complete the more complex part of the task with the sound hand.
Families need time to assimilate the information provided by the team because they are the ones who must make informed decisions concerning the prosthesis for the child. When parents have the opportunity to select the type of terminal device they want, they may be more committed to the total program. Even though the team provides information, support, and training, the parents must follow through on a day-to-day basis. They help the child develop both a consistent wearing and use pattern when performing daily activities.
Infant Prosthesis/No Active Controls
At CAPP, the prosthesis for the infant is a lightweight endoskeletal or exoskeletal transradial (below-elbow) prosthesis with a nonactive terminal device. An infant chest harness is used instead of the traditional figure-of-8 harness (Fig 34D-1.). A polyvinylchloride (PVC) gauntlet covers the socket to provide a friction surface. It prevents the baby from sliding when the prosthesis is used for support on a hard surface. Parents are given the choice of a CAPP Terminal Device No. 1 (CAPP TD), a Dorrance 12 P hook, a Steeper foam-filled infant hand, or a Centri infant hand. The advantage provided by the CAPP TD and hook is that they are both able to hold an object. In addition, the CAPP TD with its large grasping surface and good friction cover provides a secure hold on objects. Even though the little passive hands provide no grasp function, families do request them because of appearance.
Evaluation of and Training With the New Prosthesis
The prosthesis should be evaluated when it is delivered to the patient to make sure that it conforms to the prescription and standards of the clinic. The occupational therapist observes fit, comfort, and function of the prosthesis during normal use. By watching the baby move and play, the therapist evaluates the stability of the socket and harness. Any signs of restriction or discomfort are reported to the prosthetist so that the necessary changes and adjustments can be made.
The therapist sees the baby and family two or three times during the first month to provide both information and support as well as tell parents how to do the following tasks:
- Correctly apply and remove the prosthesis.
- Maintain the prosthesis in good condition by washing the harness, clean the inside of the socket, and use clean stump socks each day.
- Encourage the baby to use the prosthesis in normal play activities.
- Learn to recognize when the socket and harness are tight. Take the child to see the prosthetist for necessary adjustments.
Grandparents, siblings, baby-sitters, and other extended family members are encouraged to attend one or more sessions. Their role is vital in cooperating with parents to establish the development of a consistent wearing pattern. It is reasonable and desirable for the prosthesis to be worn the entire time the baby is awake. It may be removed when the baby sleeps, takes a bath, or swims. "However, wearing patterns may vary with climate changes and individual parental needs."
When the baby receives the first prosthesis, his body and arm movements may be awkward for a few weeks or so. The family need not be overprotective, but should provide assistance if the prosthesis becomes pinned under the baby's body or caught in furniture. The baby is encouraged to include the prosthesis to stabilize body weight when creeping on all fours (Fig 34D-2.) or when pulling to stand. Large balls or stuffed animals are presented so that the child learns to clasp between the sound arm and the prosthesis (Fig 34D-3.). Parents are also asked to place a toy or cookie in the terminal device. The 8- to 12-month-old may try to remove the item or totally ignore it. Over time, as the parents continue to place objects in the terminal device, the toddler will become aware of the holding function and mimic this behavior. Gesell and Ilg describe a similar developmental activity in which babies learn to place cubes in and out of a cup. This adaptive behavior becomes more meaningful and engrossing as the baby gets closer to 18 months of age. To make it easy for the toddler to open the terminal device, the CAPP TD should have a soft spring. Since the manufacturer issues the terminal device with a regular spring, the prosthetist should be reminded to make the change.
Readiness to Activate the Terminal Device-The CAPP Approach
At CAPP the control line or cable is added to the transradial prosthesis when the child demonstrates certain developmental behaviors that indicate the ability to learn how to use an active terminal device. The readiness criteria are as follows:
- The child is able to follow simple directions that have no more than two steps.
- The child demonstrates an attention span of at least 10 minutes.
- The child demonstrates an awareness that the terminal device can hold an object and attempts to open it with the sound hand.
- The child shows an interest in activities that require the use of two hands.
- The child shows some willingness to be handled by the parent or therapist.
Some of these behaviors become apparent near the child's second birthday and are based on principles of development. Pulaski says "the child at two makes a transition from sensory motor experience to mental activity." The mental activity is demonstrated by the child's ability to follow simple directions and to understand cause and effect. According to Gesell et al., the 2- to 2½-year-old has the beginning of interest in constructive activity such as building with blocks and fitting simple toys together. He also has an elementary interest in imaginative play. It is therefore appropriate to capitalize on this period of cognitive and motor development by introducing the active control line or cable. The child integrates the opening of the terminal device with fine motor bimanual activities and then relates it to everyday play. However, these cognitive and motor skill changes do take place during the middle of the "terrible twos" when the child may resist being handled. Sometimes after the control line is added and everyone gears up for the training, the child is no longer cooperative. No harm is done if the therapist and family remain flexible. They may postpone the training time or pursue alternative nonstruc-tured training methods.
Evaluation of the Prosthesis With the Active Terminal Device
The control line and figure-of-8 harness are added to the current prosthesis, or a new prosthesis may be fabricated. The terminal device may be a CAPP TD No. 1, a 10X Dorrance hook, or a child's size mechanical hand.
The size and contour of the child's anatomy as well as the range of motion and strength of the shoulder girdle are certainly not the same as the adult's. Therefore the following components and adjustments should be standard for a child's prosthesis to maximize efficiency and ease of operation.
- The cross point of the harness is stitched in the center of the back a little lower than C7 rather than toward the sound side.
- The control attachment strap and lower axilla loop strap should pass over the lower third of the scapulae.
- The CAPP TD needs a soft spring, the 10X hook should have a quarter to half of a rubber band, and both should open and close smoothly.
- The cable housing should be lined with Teflon to increase the efficiency of the cable system.
Whenever a new prosthesis is issued, the following care and maintenance procedures are reviewed and reinforced with the family.
- Clean the inside of the socket each night. Wash the harness at least once a week.
- Brush dirt or sand from the pulley system of the CAPP TD. Use an air hose at the gas station if necessary. Immerse the ball bearing of the hook in alcohol to clean.
- Change the CAPP TD covers when they wear out. Remove all rubber bands from the hook when the elastic deteriorates. Replace with new ones.
- Retread the neoprene lining of the hook when it wears out to maintain complete closure of the hook fingers.
- Clean the glove of a mechanical hand with alcohol, a manufacture's glove cleaner, or a special detergent such as "Simple Green."
- Adjust the wrist friction so that the terminal device does not inadvertently move during use.
- Go to the prosthetic shop every 4 months. Have the harness adjusted as the child grows.
Control Motion Training
Controls training or initial training is conducted by the occupational therapist to teach the child to open the terminal device. The therapist sits behind the child or next to the arm with the prosthesis. The child holds a toy in the sound hand while the therapist moves the shoulder on the side of the prosthesis into humeral flexion (Fig 34D-4.). Pressure is exerted by the harness under the axilla on the sound side. The child usually moves the shoulder or upper part of the body to avoid the pull of the axilla loop. The result is slack in the control system, which prevents ease of operation of the terminal device. To counteract the problem and minimize frustration, the therapist stabilizes the shoulder on the sound side and encourages the child to reach forward to place a toy in the terminal device. The therapist helps with the secure and correct placement of the toy and extends the child's shoulder to relax tension on the control line to close the terminal device. Once the child has completed the activity, he may remove the item with the sound hand.
If the child is less inclined to sit at a table to learn the controls, the control attachment strap may be tightened. When the child bends over or reaches forward toward a toy, the terminal device opens. The therapist or parent then calls attention to the open terminal device.
The therapist definitely provides "hands-on" assistance during this period. Two or three short training sessions a week for 2 to 3 months are reasonable to reinforce learning the control motion and to provide a successful experience for the child. The parents must be included in the therapy sessions in order to assist the child at home.
Although the focus is on learning the control motion, the child does not respond well to "drills." It is best to use developmentally appropriate bimanual toys and games in order for the child to relate the control motion to purposeful play. At CAPP we do not ask the child who has a unilateral limb loss to use the prosthesis to perform dominant hand skills, but rather to assist the sound hand in two-handed tasks. Appropriate activities that provide repetitive opening and closing of the terminal device may be used for this phase of training.
- Use threaded nesting barrels such a "Kitty in the Kegs" or small jars and bottles with toys or treats inside. (Hold the barrel or the jar in the terminal device. Remove and replace the top with the sound hand).
- String large wooden or plastic beads with a strong cord or leather lace. (Hold the bead in the terminal device and hold the string with the sound hand).
- Use fat felt-tipped pens with loose caps. Hold the marker in the terminal device, and remove the cap with the sound hand to scribble on paper.
To master the basic control motion the child must learn to independently perform the following skills:
- Open the terminal device, and place an object securely inside.
- Extend the shoulder to relax tension on the control line to close the terminal device. Time the closing to prevent the object from falling out.
- Release an object from the terminal device. Either pull it out with the sound hand, or actively release it by using the same control motion.
To open the terminal device at the midline of the body the child must use biscapular motion. Some children learn automatically. Others may need assistance.
During use training the child acquires prosthetic skills that facilitate use of the prosthesis as he works to develop a natural and spontaneous use pattern. While functional use of the prosthesis cannot be compartmentalized, young children do not assimilate all facets of training at once. Stages of prosthetic training overlap with each other, and learning takes place over a period of time along with the acquisition of other developmental skills.
The focus during this period is on the prehensile use of the terminal device. However, the child should continue to use the prosthesis as a unit to stabilize or support objects (Fig 34D-5.).
Skills that relate to prehensile function are introduced as the child is ready to learn them. Initially the therapist focuses on the following skills:
- Place an object securely and accurately in the terminal device. Reposition the object as needed.
- Refine the size of terminal device opening, especially for small or thin items (Fig 34D-6.).
- Reposition or change the position of the terminal device as required for different activities.
- Actively release an object from the terminal device by using the control motion. (Learn to drop the object on the table or floor. Actively toss the object from the terminal device into space.)
To assist the child to learn specific skills the therapist demonstrates the activity and provides verbal instruction. In time only verbal cues may be necessary. As new, fine-motor, manipulative tasks are presented, the child is encouraged to motor-plan and problem-solve for the new activity without assistance. If the child has difficulty, the therapist asks how the task may be done another way. This opportunity allows for a trial-and-er-ror approach before the therapist intervenes. Performance will vary depending on the child's natural abilities and motivation. The therapist may need to do part of a more complex task and then allow the child to complete the activity.
There are many ways to approach an activity. If the child appears awkward when doing the task, the therapist should correct the method of prosthetic performance. For example, many children either avoid prepositioning the terminal device or repositioning an object in the terminal device. They frequently substitute shoulder motion to place the terminal device in a position of function and need reminders to perform the task more efficiently. A helpful hint about the CAPP TD No. 1 is to position it so that it mimics the sound hand.
Although it will always be appropriate to place an object in the terminal device with the sound hand, the child must learn to actively grasp an item from a surface with the terminal device, especially if the sound hand is occupied. Likewise, to achieve a fluid movement pattern with the prosthesis, the child may practice reaching forward with both the terminal device and sound hand to grasp a stationary object in space. It is best to avoid "one-handed drills" and use a more spontaneous two-handed approach with toys such as, tike bike, tricycle, rocking horse, see-saw-swing, shopping cart, doll carriage, wheel barrow, rolling pin, and Play-Doh(Fig 34D-7.).
Since the child's work is play, toys, games, crafts, and other purposeful bimanual tasks are used to integrate these skills into the child's use pattern (Fig 34D-8.). In fact the preschool youngster does well with activities that encompass imaginary play such as a tea party, washing dishes (Fig 34D-9.), washing doll clothes and hanging them on a line, planting flowers or seeds in a pot (Fig 34D-10.), grocery shopping, and dress-up play with costumes and makeup. Playing baseball with a plastic bat and a large ball as well as outdoor fun on playground equipment is also highly recommended.
Before the child goes to kindergarten, the therapist introduces or reviews specific prosthetic and self-help skills. Practice in the following type of activities may help the child to function more independently in the classroom (Fig 34D-11.).
- Hold paper to cut with scissors.
- Open and close glue bottles and jars.
- Open a milk carton and package of cookies.
- Stabilize clothing to zip a jacket or button a shirt.
- Don and doff the prosthesis independently.
- Begin to learn to tie shoelaces.
The school-age child learns additional skills that are a refinement of prosthetic use. In order to hold a soft or fragile object in the terminal device, the child controls the pressure grip by maintaining a slight amount of tension on the control line. This skill is important in order to hold a sandwich or crack an egg without a mishap. To keep the terminal device closed when bending over or extending the shoulder, the child must pinch the scapulae together or shrug the harness high up on the back. These maneuvers will help to relax tension on the control line to keep the terminal device closed to tie shoelaces or shoot a toy bow and arrow' (Fig 34D-12.).
When the child acquires some degree of skill with the prosthesis, the focus in training shifts to developing more spontaneity. Although some children become more spontaneous than others, there is no magic to the training process. Practice and repetition are a definite part of building a habit pattern. While the 2-year-old delights in repetitive bimanual tasks, the therapist does much to enhance training by being creative. Parents must be present during training sessions because their involvement and cooperation are essential for ongoing success. By the time the child enters kindergarten, formal therapy is no longer necessary. However, at different developmental periods the child may need assistance with specific self-help, recreational, athletic, and avocational activities. Therefore the youngster should always have access to the prosthetist, therapist, or other appropriate team member.
Functional Need and Prosthetic Options
As the child grows and develops, function, cosmesis, interests, and skill levels change. The therapist is usually aware of these needs and may be in a position to introduce different prosthetic components or recommend changes to existing ones. Early in the use-training period, the therapist or child will identify a need for more prehension force. The child may become repeatedly more frustrated when he is not able to hold an object securely in the terminal device as resistance is applied by the sound hand. The child who has the CAPP TD No. 1 will need to replace the soft spring (Hosmer 71622) with the regular spring (Hosmer 71623). This exchange is made as soon as the child has enough operating force to pull against the increased resistance. A third and much harder spring is available for the older school-aged child.
The CAPP TD No. 2 with its automatic thumb-locking mechanism and heavy-duty closing spring provides excellent grip force and function. This component is appropriate for the teenager and adult and will soon be commercially available.
The Hosmer-Dorrance voluntary-opening hook uses rubber bands to provide grip strength. For the young child, a quarter to half of a band may be added at a given time according to the youngster's available excursion and operating force. Some preteen and teenage boys may actually switch to a hook from some other device because they like the configuration, the fine tip prehension, and the option of adding rubber bands to increase grip strength. The hook is especially versatile for grasping the handle bars of a bike, for tool use, and for heavy-duty work.
Voluntary-closing Adept terminal devices from Therapeutic Recreation Systems (TRS) also provide a variety of benefits. Crandall and Hansen report a study in which 16 amputees out of 20 with transverse forearm deficiencies who originally used voluntary-opening hooks switched to the Adept devices. The children cite specific advantages for themselves.
- The voluntary-closing device provides increased prehension force as well as greater control over the amount of force exerted to do an activity.
- The voluntary-closing device makes it easier to lift heavy objects and to grasp cylindrical shapes such as a bicycle handlebar and a baseball bat.
Electric hands that are myoelectrically controlled provide excellent grip force, ease of operation, elimination of the cable and harness system, as well as good cosmesis. Use of this type of transradial prosthesis usually depends on available funding resources. Because myoelectrically-operated prostheses are more expensive than the cable-operated ones, state agencies and some insurance companies may not routinely pay for them. CAPP does not have a myoelectric program for infants. However, when funding is available, we use the Otto Bock, two-state, two-site control system and the appropriate electric hand to fit children as young as 3 years of age.
An increasing number of parents will not accept any other terminal device except a hand. Therefore the child's-size mechanical hands from Steeper, Ltd., may be pleasing in appearance and may be acceptable as an alternative to other devices (Fig 34D-13.). Unfortunately, the hands do not have the same power pinch as the electric hands and do not provide the same potential for function as the CAPP TD No. 1 and the Dorrance hook. The child must use excessive operating force to achieve only minimal opening. Depending on the spring setting, the Steeper 2-in. hand may not close completely. For the 2-year-old who is just learning active operation of the cable-controlled terminal device and for the therapist doing the training, this hand may provide more frustration than function.
Older youngsters who are involved in school or community-based athletic programs are usually required to remove the prosthesis for body-contact sports. For certain activities, the youngster may wear the socket, but the terminal device is perceived to be a problem. The TRS Super Sport Hand can be used as an alternative. "This device is made of soft, flexible polymer and is shaped like a "cupped hand."
The type of prostheses and components that are offered in a particular amputee center may depend on the following:
- The center's history and experience with certain components and control systems.
- Research components developed in a particular center.
- Available financial resources and subsidized funding for prostheses and components.
Nonetheless, patients and their families have an ongoing need for up-to-date information about new and available components and should have some say in the prescription process. Over time, if the patient and/or family decides not to pursue prosthetic fitting, the clinic team should accept that decision and keep the "door open" for future assistance.
THE CHILD WITH BILATERAL UPPER-LIMB AMELIA
Support and Guidelines for the Family
When a child is born with bilateral upper-limb ame-lia or other severe limb deficiencies, the family needs emotional support, guidance, and information.As one CAPP mother so poignantly said, "We were in so much shock we did not know how to act or what to do." An experienced, sensitive team can share the family's fears and concerns and, over time, help them to refocus on the child's abilities.
The occupational therapist evaluates the infant's development and explains what to expect as the baby matures. Guidelines for handling the baby's special needs are also presented. For example, babies with severe limb loss have less skin surface from which to disperse body heat. They are frequently very hot and perspire excessively around the head and neck. Parents are instructed to use lightweight clothing and allow the baby's lower limbs to be exposed. The benefits are twofold. The baby remains cooler, and the feet are free to touch and explore the environment.
The Baby's Ability to Adapt
It is important to understand that a baby with no arms has a structural deficit and not a neurologic impairment. Unless there is a secondary problem, development should follow a specific sequence according to the maturation of the neuromuscular system.However there are variations in the establishment of specific fine and gross motor milestones. Obviously, babies with no arms or with short transverse deficiencies above the elbow will not be able to creep on all fours. However, these children do come to a sitting position, scoot on their bottoms, and push to a standing position to walk. Some babies experience delays, while others perform developmental skills within the normal time frame. Although no special therapy is needed, the parents need to know when and how to assist the baby through various stages of neuromuscular development.
Gesell describes adaptive behavior "as the child's ability to make adjustments in perception, orientation, as well as manual and verbal skills, which then allows him to initiate new experiences."
With neuromuscular maturation and voluntary control over body movements, the baby explores ways to move in space and to manipulate objects in the environment. With encouragement, the baby may learn to use the parent's leg as support to push to an upright position. Later the child may come to standing from a prone position by pushing up with head and legs or use the body as a lever against a stationary object (Fig 34D-14.).
Children with high-level upper-limb loss learn very early to substitute foot use for missing arms.Schmid says "that the foot skills of these children develop in a sequential pattern which imitates that of the upper extremity. Even grasp between the great and second toe occurs within the same time frame as the grasp between the thumb and finger." In addition to using the feet, children also hold and carry objects in the mouth or between the chin and shoulder.
Rationale for Prosthetic Fitting
For the child with bilateral upper-limb amelia, use of prostheses is presented as an option or an alternative way to perform selected activities. The team provides the family with information on appropriate components and discusses the real function of prostheses. Before a prosthesis is prescribed, the following questions must be addressed:
- Does the child have a functional need for a prosthesis? Will the prosthesis interfere with the child's development?
- Is the child able to use the components and control systems currently available?
- Do the parents want a prosthesis for the child? Are they ready to commit to the training process?
If at all possible, the baby should receive the first prosthesis before the developmental period of the "terrible twos." It may be prescribed when the baby achieves independent sitting balance as long as it does not interfere with the ability to move freely. At CAPP we sometimes wait until the child is walking. When the feet are used for ambulation, the child may be more enthusiastic about wearing the prosthesis.
One or two shoulder disarticulation prostheses may be suggested for the first fitting. One socket covers less of the chest area and may keep the weight, bulk, and heat to a minimum. However, it may be easier to suspend two sockets on the body and give the child a greater sense of balance. These options depend on the child's size as well as the contour and muscle mass of the chest and trunk. Essentially, the clinic team must determine which fitting will provide the best comfort and meet the child's functional needs.
The First Infant Prosthesis With No Active Controls
At CAPP the prosthetic fitting of choice for the child with no arms is an endoskeletal shoulder disarticulation prosthesis. It may include an aluminum frame or vented laminated socket and a 10X hook or CAPP TD with no control cable. The elbow joint is usually assembled from CAPP components, but a new push-button elbow joint is commercially available from the U.S. Manufacturing Company. The forearm and humeral segment lengths are made of pieces of PVC tubing (Fig 34D-15.). These segments must be the appropriate length to allow for the following functions:
- The terminal device must reach the mouth at the midline of the body when the elbow is fully flexed.
- The forearm must clear the table top when the elbow is flexed at 90 degrees.
The Training Period
After the prosthesis is evaluated for fit, comfort, and function, the parent must learn how to encourage the child to use it. The daily wearing pattern may be full-or part-time, but the prosthesis should not interfere with foot use or the development of other gross motor skills. The key, however, is a consistent wearing pattern. As the parents repeatedly place toys and finger food in the terminal device, the child will learn about the holding function. Parents will need to assist the child with many of the activities such as unlocking the elbow to bring food to the mouth.
Since children without arms do not have active shoulder motion, they cannot reach out and clasp large or small objects between the segment lengths. It is possible, however, to carry a large lightweight toy that is wedged between the forearms. Likewise, the child must use body motion to push or move an object with the prosthetic forearm or terminal device. Because the toddler can perform most age-level play activities with the feet, it takes creativity and perseverance on the part of the therapist and parent to encourage use of the prosthesis. When the child wears shoes so that his feet are not accessible, the following types of activities may be used in the training process (Fig 34D-16.):
- Scribble with a crayon that is secured in the hook.
- Push or maneuver cars, trains, or other toys on a table surface.
- Pull a toy with a string that is secured in the hook.
- Paint in a "Paint with Water Book." Secure a brush in the hook.
- Hit a drum or xylophone with a mallet secured in the hook.
Rubber band loading on the hook is minimal during this phase of training, and objects may easily fall out during use. An extra band placed over the hook tip will secure most thin items and prevent them from slipping.
At 15 to 20 months of age the toddler begins to feed himself with a spoon. Children without arms may also show signs of readiness to perform this task with the feet. It is difficult to learn to eat with a spoon in the terminal device, but if there is interest and motivation, the activity may be introduced during this developmental time period. A swivel spoon is placed in the hook and secured by a rubber band. The push-button elbow is unlocked and placed in the free-swing mode. The child uses trunk motion to place the spoon in the dish. Soft food will stick easily. With practice the youngster will learn to scoop food by pushing the spoon against the high rim of a special dish. To bring the spoon to the mouth, the child leans the forearm on the table and forces the elbow to flex. This method of eating is very complex and requires not only practice but assistance from the parent (Fig 34D-17.). The child will not gain independence in this skill for several years. The method of bringing the spoon to the mouth depends on the control system that is used to power the elbow unit. The older child who uses either an electric elbow or one with a dual-control cable system will be able to lift the forearm to the mouth with much less effort.
Activating the Terminal Device and Learning the Control Motion
The passive prosthesis provides only minimal function for the child without arms. The need to do selected dominant-hand activities with the prosthesis prompts the activation of the terminal device as soon as the youngster has the cognitive ability to learn the controls. The terminal device of choice for the active prosthesis is a Dor-rance 10X hook because it provides fine tip prehension, nonprehensile hooking action, and a clear view of the objects to be grasped.
The terminal device may be activated with either a Michigan External Power System (electric hook) with a push-switch control or a body-powered single control cable and a thigh strap. Each system has its advantages and disadvantages. The team must decide which one will meet the individual patient's needs and abilities. The Michigan External Power System can be used with the endoskeletal type of prosthesis and retain the manual elbow unit. The push-button control is placed inside the top of the socket, and the child hits the button to open the hook. When the child relaxes away from the switch, the hook closes by rubber band action. This method allows the terminal device to open and close in a stationary position. Unfortunately, this system provides limited pinch force because the motor tolerates only about three fourths of a rubber band. If more bands are applied, the motor usually malfunctions. While the hook is easy to operate, the lack of pinch force soon becomes a problem when toys and other items are easily dislodged.
The other alternative is to use an exoskeletal prosthesis with a single control cable to close the hook.This type of prosthesis has a nudge control on the socket to lock and unlock the positive-locking internal elbow unit. Even with a half of a rubber band on the hook, the child does not have sufficient chest expansion to move the cable. Therefore a thigh strap control is necessary to open the hook. The potential excursion provided by the thigh strap allows for the following results:
- Full or at least functional opening of the terminal device without undo exertion on the part of the child.
- Potential to add rubber bands to increase grip strength.
- "Feedback" through the cable system.
In the beginning it may be more time-consuming and a little more frustrating for the child to learn the control motion with this system. First, the therapist stabilizes the child's pelvis and assists the child to bend the trunk to open the hook. The youngster then assumes an upright position. Because the terminal device cannot open and close in the same position, manipulation of objects on a table surface is impossible. The therapist must place the toy in the hook instead of asking the child to actively grasp it. With practice the child learns to use shoulder elevation and trunk rotation to open the hook. This refinement allows the youngster to perform tabletop activities at the midline of the body.
Once the control motion is refined, specific skills are integrated into the use pattern. Initially the child learns to grasp, lift, and carry toys from place to place. Later he will learn to push an object into the desired position with the unopened hook before attempting to grasp it(Fig 34D-18.). Sometimes an item will slide across the table when the child tries to grasp it with the hook. To minimize this problem, it is necessary to place the stationary hook finger against the object before closing the terminal device. Rubber tubing applied to the stationary finger will also provide a better friction surface. The child works best when motivated with toys such as wooden puzzles with large knobs, simple card games with cards in a rack, play food and dishes, as well as small trucks, cars, and trains. The Fisher Price barn, garage, zoo, schoolhouse, etc., provide imaginary play opportunities that encourage fine prehension and manipulation of objects with the hook terminal device.
Initially, the therapist prepositions all the friction components to place the terminal device in the desired position of function. The child must master this skill as soon as possible to lessen dependence on adult intervention. The shoulder, elbow turntable, and wrist must be tight enough to maintain friction and not move unnecessarily when the child walks, plays, or uses the prosthesis for function. However, these components must be loose enough for the child to reposition them when necessary. The child pushes either the humeral or forearm segment of the prosthesis against a stationary object in the environment to move the shoulder or elbow turntable. To preposition the hook or to secure an object like an eating or writing utensil in the terminal device, the child frequently uses the foot(Fig 34D-19.).
The child may use the shoulder disarticulation prosthesis to eat, write, and carry objects. Without active shoulder motion this type of limb provides limited function. In fact, it requires extensive practice to achieve a degree of skill, speed, and proficiency with this type of prosthesis. Over time, wearing patterns vary. Some children will always use prostheses to perform selected activities, while other individuals will wear and use them for only a specific developmental time period.
Activities of Daily Living and Alternative Methods of Performance
The concept of adapted performance is essential to the child with severe upper-limb loss. The prostheses never provide total independence and were never meant to replace foot skills (Fig 34D-20.) and other problem-solving methods. Celikyol describes adapted performance "as encouraging the patient to approach and solve tasks by using the entire body adaptively and to look beyond conventional methods of arm and hand use to stabilize, grasp, and move objects in space." The occupational therapist helps the child to participate in activities of daily living by demonstrating adapted techniques and experimenting with adapted equipment (Fig 34D-21.). An activity may be introduced during the same time frame in which an able-bodied child attempts the task. The limb-deficient child may accomplish part or all of a task quite easily. Because dressing and toileting skills require considerable practice, coordination, and effort, the individual may not achieve independence until the teen years. For some activities, assistance may always be needed.In addition to experimentation and practice, these children need to maintain slim, flexible bodies. Any excessive weight gain or limitation or loss of range of motion may compromise adapted performance and independent function.
Most children with upper-limb loss have the potential to live full and productive lives whether they wear a prosthesis or not. These youngsters go to regular school, participate in neighborhood and community activities, and develop skills based on their natural abilities and interests. They respond positively to a treatment program that provides the following:
- A developmental approach.
- An understanding and experienced clinic team.
- A treatment program that considers the psychosocial, functional, and prosthetic needs of the child and family.
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- Clinical experience, long-term observation, exchange of information with other health professionals, and accumulated lecture material from the Child Amputee Prosthetics Project, University of California at Los Angeles, 1972- 1992.
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Chapter 34D - Atlas of Limb Prosthetics: Surgical, Prosthetic, and Rehabilitation Principles