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Early Upper Limb Prosthesis Fitting: When and What Do We Fit

Julie Shaperman, MSPH, OTR
Samuel E. Landsberger, ScD
Yoshio, Setoguchi, MD

ABSTRACT A survey of child amputee clinics in North America explored early fitting of children with unilateral below-elbow limb absence. Responses from 45 of 80 (56%) clinics revealed that most clinics prefer to fit at 6 months and add an active control system by 18 months. These are earlier ages than had been reported in the literature. Myoelectric hands with single site controls are often applied before 1 year. Responders indicated that child development guides the timing for initial fitting and the change to an active terminal device. Independent sitting is the most-used indicator for first fitting; awareness of cause and effect indicates readiness for activation. Passive hands are most often fitted initially. Approximately equal numbers of clinics prefer to use voluntary opening and voluntary closing terminal devices in the active fitting. Myoelectric hands are increasingly used. No significant differences were found between timing and terminal device preferences among clinics in various regions of the US and Canada and between Shriners and non-Shriners Hospitals. Financial considerations were not important in selecting the terminal device except in one-third of clinics at the time of activation. Parents are doing more of the training than was reported in the past, and few clinics use objective tests to measure outcomes of fitting. Responders identified many features they would like to include in a child's new terminal device.

Keywords: arm prostheses, amputee, artificial limbs, disabled children, child development.

When do children with unilateral below-elbow limb absence receive a first prosthesis? When do these children learn to operate an active control system for the terminal device? What terminal devices and control systems are fitted most often? Do we look mostly at chronological age or developmental factors as the main determiners of when and what to fit? Practitioners with experience in this field have varying opinions on these issues. Although a considerable body of literature describes fitting preferences in individual clinics, no recent large-scale survey has reported current preferences in upper limb prosthesis fitting for young children.

A survey was conducted to determine fitting practices for children with upper limb, below-elbow limb absence in child amputee clinics throughout North America. The survey was conducted to meet several objectives. First, results of the survey will give clinicians information that they can use to explain to parents how and why their recommendations coincide with, or differ from, those of other clinics throughout North America. Second, data on fitting practices could provide the basis for future studies to compare efficacy of different fitting protocols. Third, data on current clinical practice patterns can guide designers of new components to focus their efforts on components most relevant to actual use. Fourth, findings of this survey may serve as a baseline for comparison with future surveys to identify changes in patterns of patient care as new technology and experience alter clinical practices.

REVIEW OF THE LITERATURE

Recommendations for early fitting of the upper limb range from ages 2 months¹ to 2 years.² A 1972 review of literature on early fitting and training³ found that most clinics at that time fit children with body-powered upper-limb prostheses when the children could sit independently. Developmentally, this usually occurs between ages 6 and 10 months. Two studies report that fitting before age 2 years is less likely to result in prosthesis rejection than fitting after age 2.^2,4

Several publications attempt to define the developmental indicators that tell clinicians that a child is ready to learn to operate the terminal device. Studies conducted at the UCLA Child Amputee Prosthetics Project defined developmental factors involved in early learning to operate body-powered terminal devices. Wendt⁵ found that only four of 17 children provided with voluntary-opening, body-powered terminal devices during the first year of life, but given no training, learned on their own to operate them. All of the children later needed some training. Those who did discover how to operate the terminal device needed to build habits of incorporating the terminal device in bi-manual tasks. An earlier study of the sequence of learning to operate a body-powered terminal device used motion-picture time samples taken daily as 10 2-year-old children were shown how to perform the control motion.⁶ At first, the children tended to open the terminal device manually and hold it open by taking up cable slack. Then, they learned to relax cable tension to allow the terminal device to close. The children first learned to open the terminal device to grasp an object, but did not generalize this skill to perform the same control motion to release an object unless instructed. In another study, Trefler⁷ reported that seven children with voluntary opening terminal devices could learn to drop objects before learning to pick them up; this pattern developed at 15 months of age. This study was replicated with long-term follow up of nine children.⁸ The objective of these studies was to observe and document the children's developmental pattern of learning terminal device operation. The goal was to find a method of introducing active terminal device operation that fit naturally with the child's normal development and that resulted in skillful, spontaneous use of the terminal device. While all of the children became good prosthesis users, the children who were introduced to active operation during the first year of life, those who were taught active operation at age 15 months, and those who learned to operate the terminal device at age 2 years demonstrated equal skill in performance and equal acceptance at age 3 years. This led to the practice of waiting for developmental cues that suggested the child could learn terminal device operation easily without making excessive demands on the family and child.

The studies also identified developmental readiness criteria for starting training in terminal device operation.⁹ Developmental readiness usually appeared at age 2 to 2 years. Publications show that other clinics have adopted these developmental indicators and techniques of instruction.^3,4,10,11

Often the timing of fitting and training is dependent on the technology available. In the past, several authors^12-15 advocated initial fitting and training with myoelectric hands in the pre-school period (2 to 4 years) until a new, single-site "cookie crusher" infant hand was developed. More recently, Stocker¹⁶ recommended fitting myoelectric hands with a single site control at age 4 to 6 months. The sensitivity of the "cookie crusher" system is adjusted so the child only needs to "wiggle" or move the arm to activate the terminal device. Associations between the "wiggle" and opening the hand are developed with conditioning regimens used by parents, or they evolve with the child's own awareness of cause and effect. This technology makes much earlier fitting with myoelectric hands more feasible. With earlier fitting, Stocker¹⁶ claimed that children develop earlier purposeful use of the hand. Hubbard¹⁵ noted that children are able to participate in meaningful training with a two-state (more controllable) myoelectric system when they reach age 2 years. In contrast, Ballance¹⁷ found no relationship between skilled use of a myoelectric hand and age of fitting.

One concern with the reports cited is the authors' definitions of "success." It is reasonable to assume that if the clinic recommends fitting at a particular time, it must be related to some successful outcome. Most of the authors implied that regular prosthesis wearing, skillful use, and acceptance indicate success, but most did not define it or objectively measure it. One scale to measure prosthesis wear, operating skill, use, and acceptance has been developed,⁴ but it has had limited use.¹³ The recently developed Prosthetic Upper-extremity Functional Status Index should offer clinics an opportunity for more consistent measures of acceptance and performance in prosthesis use.¹⁸ A clinic in Ankara, Turkey¹⁹ described success in terms of the person's overall habilitation. That is, can the person function well in adult society? While this is clearly the most meaningful outcome measure, it is impractical to apply in most clinic settings that must make day-to-day treatment decisions for young children.

The consensus of published reports to date is that most children receive a first prosthesis during their first year of life and receive some type of instruction in active terminal device operation during the second or third year of life. Within this general plan, there is considerable variation, and many clinics have never reported their fitting protocols for young children. Results of this survey may better define the current state of this area of clinical practice.

METHODOLOGY

Child Amputee Clinics throughout North America were identified from two sources: The Association of Children's Prosthetic-Orthotic Clinics and the Amputee Coalition of America. After eliminating overlaps (clinics listed by both organizations), 80 clinics were found. A 15-question survey instrument was developed. The survey was carried out following published procedures.²⁰ Three clinics provided data on test-re-test reliability (78%) and two other clinics responded to content validity assessments, which proved excellent. The final survey form, cover letter, and addressed, stamped return envelope were mailed to the 80 identified clinics. Those who did not respond within 2 weeks (3 weeks after mailing) received a second mailing. A third mailing was sent after another month. Most surveys were mailed to named individuals working in the clinics rather than sending them impersonally to "director" or "therapist."

Fifty clinics (62.5%) responded to the survey. Of these, 45 (56%) were usable for data analysis. Five returns were too incomplete or illegible for use. Data were coded and entered into an Excel spreadsheet. Analysis used means and standard deviations, medians and quartile measures, and frequency distributions as appropriate for each question. Some data comparing responses of clinics by facility type and area were further scrutinized using t-tests or chi-square analysis. Results are compared with reports in the literature.

RESULTS

Responses came from 24 states in all sections of the US and from eight Canadian Provinces. Response regions are shown in Table 1 and indicate that responders are relatively representative of the group as a whole. Responders were primarily occupational therapists (N = 33) and some responses came from prosthetists (N = 4), physicians (N = 4), and physical therapists (N =4). Those who responded had an average of 13 years experience working with children with limb absence. The range was 3 to 45 years. The responders also estimated the number of children in their clinic with unilateral limb absence below the elbow. The average number was 21, range was 15 to 87 children.

Responses to each survey question are given here. Additional comments are in the discussion section that follows.

1. What developmental signs tell you that a child is ready for a first fitting? Responses are listed in Table 2 . Independent sitting continues to be the most frequently cited indicator for first fitting. Clinicians also look for children to explore their sound hand and try to hold things using substitute holds in the elbow fold or against the body. Five of the reported developmental indicators related to gross motor factors, two related to hand use or prehensile function, while other indicators related to parental request and cognitive factors (e.g., follows instructions). Two clinics report that only chronological age, not development, is important in determining when to fit.
2. At what chronological age are children with unilateral below-elbow limb absence usually ready to receive a first prosthesis?The median age for first fitting was 6 months, with a range of 3 to 48 months. Two-thirds of the clinics prefer the first fitting at 5 to 7 months of age. All but two clinics prefer the first fitting by 18 months of age; these two clinics reported fitting at 4 years of age. If these two clinics were included in calculating the mean age for first fitting, the result would be 9 months, but the median age of 6 months is more representative of the preference in most clinics today.
3. What terminal device and control system are usually fitted with the first prosthesis? Terminal device preferences are listed in Table 3 . All but four clinics fit a passive terminal device with the first prosthesis. The other four reported using body-powered systems (three voluntary opening, one voluntary closing).
4. What is the position title of the person in your clinic who has most influence on selection of the terminal device? Fifteen clinics reported that it is a team decision. The prosthetist is the key decision maker in 13 clinics, and the physician makes the decision in nine clinics. Five clinics reported that the occupational therapist recommends the best terminal device, and three clinics indicated that the parents select the terminal device.
5. What is your role in terminal device selection? Thirty six responders indicated that they evaluate the child's developmental readiness for fitting, show families the terminal device(s), and report findings to the prescription team. Nine therapists reported that they have no role in the pre-fitting evaluation or prescription process.
6. To what extent does financing influence the choice of the first terminal device? Eight responders reported that finances influence the choice a great deal or somewhat. Thirty-seven others report that finances have no or little influence on choice of the first terminal device.
7. What is the responder's personal preference in a terminal device for first fitting, assuming no financial constraints? Forty-three responders reported that they would choose the same terminal device that their clinic usually fits. Two therapists would prefer a myoelectric hand rather than the passive hand usually applied in their clinic.
8. What developmental signs do you use to determine that a child is ready for a more advanced terminal device/control system than the one first fitted? Results are listed in Table 4 . Most responses refer to increased developmental maturity indicating that the child could be taught to operate an active control system. Developmental signs guiding the change are of three types: (1) cognitive (e.g., awareness of cause and effect); (2) predictors of use of the prehensile function of the terminal device (e.g., attempts to hold objects, to open the terminal device manually, and to insert objects); and (3) predictors of ability to participate in a training program (e.g., willing to follow directions). Other developmental signs mentioned by therapists have a less clear relationship to the change of terminal device (e.g., rolling over, pulling to stand). A confounding variable was that it is often practical to add the new terminal device and control system at the time the child has outgrown the first prosthesis; even if preferred age and other developmental indicators are absent.
9. At what chronological age do you usually recommend a change to a more advanced terminal device and control system (activation)? The median age for activation is 18 months, with a range of 12 to 60 months. Again, two clinics fit children at a later age, so the mean, including those two clinics, is 23 months. All but those two clinics report that the terminal device is activated by age 3 years. The results were further examined to find out whether statistically significant relationships existed between clinics in various parts of North America and between Shriners Hospitals and other facilities. No significant differences were found when comparing age of first fitting and age at change to an active terminal device for (1) different regions of the country; (2) clinics in the US compared with clinics in Canada; and (3) Shriners Hospitals and non-Shriners Hospitals.
10. What terminal device and control system do you usually fit on a child who needs to learn to operate an active control system? Twelve clinics report that they routinely fit the myoelectric hand. The CAPP Terminal Device and TRS Adept are each preferred in seven clinics. The TRS Life Touch Hand and Dorrance Hook are each preferred in six other clinics. Seven clinics report no preferred fitting.
    
    Reports of control system preferences indicate that 12 clinics fit myoelectric controls and two others briefly fit voluntary closing body-powered systems but soon change to myoelectric controls. Nine other clinics fit voluntary closing control systems and 15 fit voluntary opening systems with the first active terminal device. Others fit a variety of voluntary closing and voluntary opening body-powered systems with the first active terminal device.
    
    The results were further examined to determine whether statistically significant relationships existed between clinics in various parts of North America and between Shriners Hospitals and other facilities in preferences for myoelectric or body-powered terminal devices. No significant differences were found when comparing clinics in the US with clinics in Canada and comparing Shriners Hospitals with non-Shriners Hospitals. The comparison did not consider clinic size and thus, the number of children fitted. Results may have been different if those data were available.
11. To what extent does financing influence the choice of the active terminal device? Fifteen clinics reported that financing affects the choice a great deal or somewhat. The other 30 clinics reported that financing has little or no effect on choice of the terminal device and control system in the first active fitting.
12. What is the responder's personal preference in a terminal device and control system for the first active prosthesis? Again, responders primarily followed their clinic's choice. Only one responder would choose a myoelectric hand instead of the body-powered terminal device that the clinic usually fits.
13. What treatment approach and schedule do you prefer for teaching a child to operate the active control system? Responders indicated their first, second, etc. choices among options. Only first and second choices are reported here. The first choice of 23 responders was to have the therapist teach the child in their center; whereas 10 responders prefer to teach the parent to carry out a home program. As second choice, 11 responders would teach the parent to carry out the training program at home, 11 would let the child learn by trial and error, and 11 would transfer the training to a therapist in a facility near the child's home. Some report that no training is given at all.
    
    Preferred duration and frequency of training sessions in the majority of reporting clinics were for a few brief, intensive sessions. Thirteen therapists reported that they carry out an extended series of training sessions in the clinic. Thirty-two therapists reported that they conduct a few brief orientation sessions to show parents a few techniques for use at home.
14. Do you use any objective tests to measure skill and use of the terminal device? Ten clinics reported using the University of New Brunswick test, four have designed their own test, and 31 do not use any objective tests.
15. What features would you like to see in a new first or second terminal device for young children? Results are listed in Table 5 . Increased grip strength and improved appearance were requested most often. Easier operation, simpler mechanisms, better hold on objects related to size of terminal device opening, and ease of object positioning were also important. Lighter weight, wrist motion, and harness comfort were also cited.

DISCUSSION

Clinicians continue to favor early fitting with a passive hand terminal device but they prefer to fit earlier than previously reported. Currently, clinicians favor fitting at age 6 months; whereas previously, fitting was most often reported at age 9 months. As anticipated, developmental signs guide the time of fitting. Survey responses indicated a variety of signs that are important to clinicians. Besides independent sitting, clinicians look for children to explore their sound hand and try to hold things using substitute holds in the elbow fold or against the chest wall. Developmentally, infants explore their body parts, such as their hands, and they hold objects against their body much earlier than they attain independent sitting. Developmentally, children can sit at age 6 months, but still need to use their arms to support their body. The rationale for fitting when the child sits independently is that the child's arms are no longer needed for body support and may be used for manipulative tasks. Thus, it appears that fitting at 6 months occurs while the child's arms are still occupied with body support. This suggests that chronological age may actually be a more important guide to first fitting than the child's development in many centers.

Some therapists postulate that earlier fitting results in better incorporation of the prosthesis into the child's body image, and some believe that early fitting may be essential for normal neuromuscular development. While intuitively appealing, neither of these ideas is supported by published documentation. These beliefs may give added impetus to earlier fitting.

The change to a more advanced (active) terminal device also occurs earlier than was reported previously. Now, the median age preference is 18 months with a range of 12 to 60 months, while reports in the literature suggest activation at 24 months. Some clinics fit with an active terminal device at 10 to 12 months even if developmental signs are not present. These clinics tend to provide the first prosthesis at 3 to 5 months, so the device is likely to be outgrown by the time the child reaches age 1 year; thus, a new prosthesis is required. It would be too costly to fit another passive prosthesis and soon change to a myoelectric, or even a cable system, so the new prosthesis is made with the active control even though the child's age and development do not indicate otherwise. This practical consideration is a confounding variable in the survey results, because neither age nor developmental indicators are considered. At the other extreme, two clinics reported that they prefer to wait until the child is 4-years-old before they fit a prosthesis; they start with an active terminal device at that time. They also indicate that they may fit earlier if parents want the earlier fitting and will fully support the wearing and training program. Otherwise, these clinics find no advantage to early fitting. A recent assessment in one of these clinics found that fitting by age 3 years was effective, but they found no advantage to fitting before the child can walk.²¹

More than twice as many clinics preferred body-powered terminal devices for the first active terminal device compared with the myoelectric hand. The report by Atkins²² suggests that use of electric hands increased by nine percent in the 6 years prior to that report. The findings of this survey are consistent with the findings of the Atkins survey and suggest a continued increase in use of myoelectric hands. The Atkins survey also notes that children are the primary users of electric hands.

The body-powered terminal devices preferred by clinics included both voluntary opening and voluntary closing terminal devices in almost equal numbers. Several responders indicated that they start with voluntary opening terminal devices because they are easier for early learners, but they soon switch to voluntary closing terminal devices. Others indicated that they start with body-powered terminal devices and change to myoelectric hands after they are sure that the child accepts wearing a prosthesis. These comments were inserted by responders. Possibly other clinics also follow these practices, but did not so indicate on the questionnaire.

Professional roles in multidisciplinary clinics did not vary greatly among clinics. In most clinics, the prescription was written by the physician based on a team decision. Prosthetists made the choice in most other clinics while therapists and parents played only minor roles. Therapists typically conducted developmental evaluations and discussed ways in which a child might perform tasks using various types of terminal devices, but in nine clinics therapists did not participate in pre-fitting evaluations or have any voice in selection of the terminal device.

Compared with reports in earlier literature, therapists reported shorter periods of training and more involvement of parents in teaching children to operate a terminal device and encourage its use. In the past, therapists conducted sessions over a period of several weeks, but today, few parents can arrange to be away from home and/or work for such extended periods. Ten responders use the University of New Brunswick test and four have devised their own test. As health care agencies demand greater accountability and documentation to justify provider services, objective measures of wearing, acceptance, skill, and use of the terminal device will become increasingly important. Additional user-friendly, validated evaluation instruments are needed.

Two-thirds of the features desired in a newly designed terminal device for young children related to function (increased grip strength, easier operation, better hold on objects) and the other third related to appearance and durability. Clinicians' responses did not differ greatly from those of a group of parents who responded to the consumer survey of 1996.²¹ The parents selected features from a prepared list of options. Although their primary choices refer to wrist motion and action between components, the choices that refer to terminal devices are (in rank order): (1) require less visual attention to perform functions; (2) hold small objects better; (3) hold large objects better; (4) can be used in vigorous activities; (5) lighter weight; and (6) look more like a human hand.

CONCLUSIONS

Children with unilateral below-elbow limb absence are fitted with a first prosthesis when they can sit and most often by age 6 months. Passive hands are the most frequently used terminal device in the first fitting. The first actively operated terminal device is fitted when the child demonstrates awareness of cause and effect and tries to hold objects. Myoelectric hands are often fitted at 10 months and body-powered terminal devices by 18 months. Chronological age appears to be a more consistent indicator of when and what to fit than developmental signs, although both are important. Among body-powered terminal devices, there is an almost equal preference for voluntary opening and voluntary closing terminal devices. No significant differences in these patterns were found between different regions of North America nor in Shriners versus non-Shriners hospitals. Cost was an important consideration in active terminal device selection in one-third of clinics. Recently, therapists decreased the amount of training given in their clinics and rely more on parents who teach children at home. Objective measures of prosthesis skill, use, and acceptance among children are still not widely used. Additional studies are needed to objectively compare outcomes with initial fitting and activation at different ages and with various types of terminal devices.

The survey form was developed with assistance of Eve Fielder, DrPH, Director, Survey Research Center, Institute for Social Science Research, University of California, Los Angeles. Consultation on data analysis was performed with the assistance of Edward Ebramzadeh, PhD, Biomechanics Laboratory, J. Vernon Luck Orthopedic Research Center, Los Angeles Orthopedic Hospital.

JULIE SHAPERMAN, MSPH, OTR, is a Research Occupational Therapist in the Rehabilitation Engineering Program, Rancho Los Amigos National Rehabilitation Center, Downey, California.

SAMUEL E. LANDSBERGER, SCD, is Director of the Rehabilitation Engineering Program at the Rancho Los Amigos National Rehabilitation Center, Downey, California.

YOSHIO SETOGUCHI, MD, is the Medical Director of the Child Amputee Prosthetics Project at the Shriners Hospital for Children, Los Angeles, California.

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