Pre-School Myoelectric Fittings: A Thirty Year Perspective
Sheila Hubbard, P& OT, BSc (PT)
(An abbreviated version of the paper presented at the ACPOC Annual Meeting in Tempe AZ, 2009)
To review our 30 year experience with powered upper extremity prosthetics for pre-school aged children.
This paper will chronicle the development of a specialized, powered upper extremity practice at Bloorview Kids Rehab and then use the results of a literature review and the author's own experience to discuss some of the major issues of interest and controversy.
Our Powered Upper Extremity Prosthetics Program (PUEPP) had its origins back in the early 60's as a result of the thalidomide drug tragedy; a significant factor underlying the development of the prosthetics industry in Canada. The drug thalidomide, given to women in early pregnancy for morning sickness, damaged developing embryos and caused severe limb deficiencies. In response to the crisis, the government and medical profession moved quickly to establish specialized prosthetic research and training centers (PRTU's) in Winnipeg, Toronto and Montreal in 1963.
It was decided to locate the Toronto Unit at the new Ontario Crippled Children's Centre (OCCC) under the direction of Dr. John Hall as the Medical Director and engineer, Colin McLaurin as the Project Director. Bill Sauter became the Unit's research prosthetist in 1964.
This was a unique time in the history of children's prosthetics. Birth defects of this magnitude had not been encountered before and innovative approaches were required. Throughout the thirteen years of funded operation (1963-1975) the three new PTRU's, Professor Bob Scott and the Myoelectric Controls group in Fredericton and representatives of National Health amp; Welfare Canada all worked collaboratively to try to address the needs of these exceptional children. From the beginning, it was agreed that the projects would cover research and development to help all amputees, including those due to Thalidomide. The pioneering efforts of these groups facilitated the development of paediatric prosthetic practice worldwide.
Highlights of the Toronto Unit's upper extremity activity included the design and development of a variety of prosthetic components (e.g., a powered hook, elbow and wrist rotator, an electric coordinated arm and an infant passive hand), vacuum formed thermo plastic sockets, the first myoelectric fitting of a child amputee in 1965 (using a UNB myoelectric control system to operate an electric wrist rotator), the establishment of an Electro-Limb Shop by the Variety Club in 1969 to manufacture prosthetic components for children and collaboration in a project to develop and trial the use of the 1st child-sized switch-electric hand (designed by Lukas of Northern Electric).
Lower extremity projects included the development of a series of swivel walker designs, a hip disarticulation prosthesis, a Van Nes prosthesis, polycentric knees, paraplegic braces (e.g., the parapodium, a cord & pulley reciprocating gait brace) the Toronto Legg-Perthes Orthosis and a variety of motorized vehicles.
Finally, the project served as a foundation for the establishment of a Rehabilitation Engineering Department at the end of the grant period in 1975. By that time it had become evident that the thalidomide children had largely rejected their electrical upper limb prostheses, preferring instead to use their own phocomelic limbs.
The focus changed and work on myoelectric control, training and fabrication procedures continued on in collaboration with the research team at the University of New Brunswick (UNB) and a number of adolescent and adult fittings were carried out over the next few years. At that time, training and fitting procedures were considered too complex for application to young children and components were only available in adult sizes.
Body-powered devices were generally prescribed – a passive mitt at 5-6 months and an activated 12P hook at 12-18 months. The children attended out-patient therapy regularly for several months or were admitted for a few weeks of intensive training. Parents had little involvement in the training process. A few children were fitted with the switch-controlled Northern Electric hands but frequent break-down led to dissatisfaction.
In 1978, things began to change after a group of us had the opportunity to hear Dr. Rolf Sörbye speak about his experience in fitting myoelectric prostheses to young children in Sweden. Inspired by his reported success and knowledge that a trial evaluation was to be conducted in the United Kingdom to assess the effectiveness of the myoelectric hand prostheses as an acceptable device for young children, we started to experiment with younger-age fittings ourselves in 1978. Three children (2yr, 9mo to 2yr, 11mo) were subsequently fitted (1978-80) with the new Swedish child-sized electric hands controlled by U.N.B. three-state control systems. Supporting us in this venture was our new Director of Rehabilitation Engineering, Dr. Morris (Mickey) Milner, who had replaced Dr. McLaurin in this role.
In 1980, a formal two-year research study was implemented to develop effective strategies for training the pre-school child to operate a myoelectric prosthesis. 1 Eighteen families agreed to participate and two training protocols were developed: one, home based with the parent as primary trainer and the other, a Centre-based program with the therapist as trainer. Both training protocols proved to be equally effective. A three year follow-up review was carried out in the fall of 1984.
Based on the success of this study and the financial support of the Ontario Government and the War Amputations of Canada's CHAMP program, myoelectric prostheses then became a standard option for children aged 2 1/2 and older at our facility. For many years we enjoyed a unique model of care, as an integrated team of clinical, engineering and manufacturing personnel were able to work together to refine and enhance the process of myoelectric fitting, identify Ramp;D priorities and develop a variety of products to meet the specific needs of our children.
From 1984 to 1985 an effort was made to try to respond to the parental demand for powered fittings at an earlier age. However the results of an 'early-bird' pilot project, involving 6 children aged 15 to 27 months, proved to be disappointing. Remote battery pack wire breakage, weight/size of the electric hands and problems calibrating the control systems effectively eventually led to inconsistency of prosthetic wear and frustration for all involved.
Fortunately, within a short period of time, technology changed significantly and we were able to take advantage of several new developments. Smaller-sized electrodes and a new infant hand enabled us to produce a lighter and cosmetic, self-contained prosthesis. At the same time, we became aware that younger-aged children could easily master the new St. Anthony "cookie-crusher" control strategy advocated by Tom Haslam in Houston. Using simplified assessment/ fitting procedures, we started to proceed directly to fit a powered prosthesis when the infant had outgrown the passive device and to allow the child to gradually discover its potential through the use of a home-based, parent-assisted, training model. 2
For the majority of fittings, components have included a VASI 0-3 hand, controlled by an OB 13E125 electrode and powered by a four cell, 150 milliamp battery. A simple friction elbow has been added for the child with a higher level deficiency. In a few cases, push switches or force-sensing resistors (FSR's) have been used instead of EMG control for the children that required shoulder disarticulation level fittings.
Once the prosthesis has been manufactured and fitted, a therapist has worked closely with the family to provide guidance and suggestions for developmentally appropriate activities to stimulate the child's awareness and use of the prosthesis at home. Parents have been shown how to progressively change training expectations so that the child has eventually been able to grasp and hold objects, carry them about and release them at will. Frequent follow-up has been required to provide support and encouragement and assess the need for socket modifications or replacement due to growth. Spontaneous use for bimanual activity has commonly been observed between 18 and 24 months of age.
Around the age of 3-4 years, when the child has required socket refitting, we have taken the opportunity to assess their readiness to transfer to a more complex control strategy. At this stage, the child has usually developed the improved communication skills and longer attention span needed to employ the requisite evaluation/training strategies. If successful, the programmable electronics have then been easily converted to a two-site system allowing the child to have voluntary control of both opening and closing. The majority of children have been able to make the transition without difficulty. In a situation where it has not been possible to locate a second site, a one-site, two-function system has been selected as an alternative.
In the case of a child that has not had any previous experience with myoelectrics or has recently had an amputation, we have used a more traditional approach. 2 Procedures have included muscle site identification, control system selection, muscle control training, system calibration and functional use training. Evaluation and follow-up training have been provided on an ongoing basis to monitor and address any changes in the child's physical, developmental and psychosocial needs. There has also been an effort to try to have a system of standardized outcome measurement in place so that data could be collected and reviewed on a regular basis.
Our total pre-school fitting experience (1978-2009) now includes 224 children (10 months to 5 years of age at the time of their first powered fitting). The group includes 115 females and 109 males, 221 with congenital limb deficiencies and 3 with acquired amputations. 128 children were left-sided, 74 right-sided and 22 were affected bilaterally to varying degrees. Subject Prosthetic Fittings/Level
Shoulder Disarticulation –7
Trans Humeral –22
Trans radial –146
Wrist / partial hand –42
Our group has been fortunate to have had the visionary leadership of individuals like Colin McLaurin, Bill Sauter and Mickey Milner, the unconditional support of our in-house medical staff, consultants and clinic chiefs (John Hall, Robert Gillespie, Ivan Krajbich and William Cole) and an exceptionally talented and dedicated, multidisciplinary workforce. There have been a succession of name changes and we have grown from a small research lab in the basement of the OCCC to a state of the art facility and membership in a large, clinical technology group at the new Bloorview Kids Rehab.
What Have We Learned?
Instead of simply providing a series of personal reflections I decided to take a look at the literature for a broader perspective. In doing so, I wanted to compare our experience with that of others in our community, to identify the issues which have generated the greatest interest and/or controversy and to see how the various investigations have led to agreement or continued debate today. The results of the review indicate that for the most part, the authors' primary focus of interest tend to fall into five major categories: feasibility, optimal age for fitting, functional benefit, psychosocial benefit and acceptance/rejection factors.
The English language literature contains a number of articles written by practitioners describing their individual experiences, management policies and fitting/ training procedures. 2 to 20 While most authors suggest it is a specialized practice, there is general agreement that young children can be fitted successfully, that they have very little difficulty learning how to operate the hands particularly if the single-site, voluntary opening strategy is utilized and they can transition to a more complex control system at 4-6 years of age. There appears to be widespread agreement on the need for a multidisciplinary team approach, that there is value to occupational therapy intervention (parental guidance and training), that regular followup is essential and most important of all, that there is a need for strong committed partnership with the family. Although there is not a lot of evidence cited, there does seem to be consensus that the children most easy to fit and likely to benefit from myoelectric fitting are those with unilateral, transverse, partial forearm deficiencies. Fittings for limb deficiencies, at or above the elbow, are more complex but generally can be managed successfully as well. 4, 7, 13, 14, 15 Results for children with longer limbs (wrist level or partial hand) are more variable and far less predictable. 7, 13, 14, 15 Similarly, the added weight and complexity of higher level fittings has led to less long term use for children with limb deficiencies at or above the elbow.
Electric prostheses are generally accepted to offer advantages in appearance, increased grip strength, ease of operation and lack of a harness. In contrast, users can typically expect increased maintenance e.g., glove & battery replacement, in addition to higher cost and weight. 10, 17, 21 Early fears of frequent breakdown and costly repairs have proven to be largely unfounded as the components manufactured for children have been quite durable and families have generally taken good care of them. 10, 14
The question of optimal prosthetic fitting age for young children has been a subject of debate as far back as 1958. 22 Although there appears to be support for fitting some type of upper limb prosthesis before compensatory patterns are established, particularly before the age of 4, opinion continues to be mixed as to what timing is best. 2, 7, 10, 14, 16, 19, 20, 22 to 33 Practice varies from 3 months to walking age for a passive prosthesis and <1 yr to 4 yrs for an activated device. 2, 7, 10, 14, 16, 19, 28
A number of studies 14, 26, 30, 31 have validated our belief that the children find it much easier to learn to operate the cookie-crusher myoelectric system than they do the cable control of a body-powered device and therefore see no reason not to fit as young as possible. It has also been suggested that there may be neurological benefits in providing maximum opportunity for the child to have bilateral function in the early developmental years.
It has certainly been my experience that the children who have been fitted young and worn their prostheses consistently have developed a very different pattern of skill and use than the children fitted at older ages. They are more bimanual, incorporating the prosthetic hands spontaneously and naturally in activities much as they might a normal, subdominant hand.
We know that hand skill development is a gradual process. If the child is fitted early, there is increased opportunity for the prosthesis to be integrated with the use of the sound limb. The child will have had practice using the hand to grasp objects so that by the time two-handed tasks are required in pre-school or kindergarten, they will be ready to participate. This skill acquisition will allow the child to keep up with peers and to integrate more readily in the classroom. Like learning a language, the earlier one does it, the more successful they are likely to be.
Since the introduction of myoelectric fittings for young children in the 70's, clinic teams have sought ways to determine if the costlier myoelectric prosthesis provided any real functional advantage. 34 A number of studies reported the use of observational type tests to evaluate the functional abilities of the users. Some researchers used rating scales to assess the child's ability to perform a number of tasks while others took a timed approach and measured the time taken to complete a set of activities. A few combined both. Researchers developed their own, one-time use instruments. Measures were not validated, numbers were small and the studies were generally not replicated. Recognizing the need for a more scientific approach, individual groups then started to try to develop measures to evaluate functional outcome for the paediatric upper limb population. The UNB test was released in 1985, 35 the Pediatric Prehension Assessment in 1987 36 and the SIRS described by Hermansson in 1991. 37
In the 1990's researchers became more interested in the use of self-report functional measures. Pruitt developed a series of functional status inventory measures including the CAPP-FSI version for preschool children in 1998 38 and the CAPP-FSIT for toddlers in 1999. 39 Our group at Bloorview started work on the PUFI in 1995 and reported the results of a reliability study with Centre clients in 2001 40 and a multi-centre validity trial in 2003. 41
In recent years, there have been two new observational type measures developed. The ACMC, 42, 43 is a Rasch-built measure, designed specifically to assess an individual's ability to control a myoelectric hand in everyday functional activity. The UBET, 44 designed specifically for the Shriners multi-center outcomes study, is based on the UNB Test but redesigned to evaluate function in bimanual activities for both prosthetic wearers and non-wearers. A number of other measures e.g., the PUFI-Adult, CHEQ and the AHA are currently under development or being validated for prosthetic use. Despite all this effort, many instruments still require further validation work, outcome measures have generally not been adopted for use in routine clinical practice and few reported studies have used a standardized approach. As a result, although clinicians continue to believe that the children derive functional benefit, they are not collecting the necessary evidence to demonstrate it.
Fortunately, that may be starting to change. Recent comprehensive outcome measurement reviews by Buffart 45 , and Wright 46, 47 have identified a growing number of prosthetic-specific and generic measures worthy of consideration to measure the functional status of children with upper-limb deficiencies. These reports have helped to simplify the selection process and should now make it easier for clinicians to start to use appropriate tools in a consistent manner to collect the evidence required. Recent investigations by James et al 48 in the US and Buffart et al 49 in the Netherlands reflect a growing awareness of the need for a multidimensional measurement approach. Renewed interest has also led to the formulation of an international, special-interest upper limb outcome measurement group (ULPOM) 50 and an opportunity for information sharing and discussion via a dedicated, web-based Google Group.
In the meantime, the paediatric prosthetic community remains divided on the issue of functional benefit for young children. For example, in 2006, James reported that the test results of a comparison of users and non-users (using the UBET and a component of the PUFI), indicated that prostheses did not improve the children's ability to function and questioned whether children should even be fitted and encouraged to use prostheses. 48 The publication created considerable controversy within the prosthetic community and opponents were critical of the methodological approach particularly in regards to the population characteristics, the definition of wearer versus non-wearer, the use of the UBET (limited psychometric investigation) and the abbreviated use of the PUFI. However, whether one agrees or disagrees with their findings, the Shriners Hospitals Study has served a very useful purpose in stimulating interest, generating some provocative questions and highlighting the need for further investigation to resolve the controversy.
Although the prosthetic community is divided on other issues, there is general agreement that appearance is an important consideration and that it is reasonable to assume that there are benefits to wearing a cosmetically attractive prosthesis, particularly during the years of basic personality development. 6, 7, 51
The impact of parental feelings and perceptions on the child's long term adjustment and outcome has long been recognized. 5, 7, 31, 33, 52, 53, 54 If the parent(s) do not like the appearance of the prosthesis or they do not think it is needed, their feelings will eventually influence the child. Parents say they prefer the more normal appearance of the electric hand and find it easier for both themselves and others to adjust and accept the child's limb difference. One would therefore assume that the parent's enthusiasm for the myoelectric prosthesis would have a positive impact on the development of the child's self-esteem. Unfortunately, we know very little from the child's viewpoint as the psychological well-being of limb-deficient children has received relatively little study or attention in the literature. 55, 56
Psychologist James Varni has been one of the few to take an active interest. After conducting a series of studies from 1989-92, he encouraged clinical teams to be aware of the factors affecting self-esteem, suggested that some were modifiable and recommended that limb -deficient children be screened for potential risk and provided with professional intervention as needed. 57
Four graduate level studies 58 to 61 have examined psychosocial aspects specifically for children fitted with myoelectric prostheses. Based on self and parent reports, these studies suggest that children and adolescents wearing myoelectric prostheses experience the same range and frequency of psychological difficulties as the general population.
The Shriners group administered the PedsQL generic core scale and the PODCI, a generic musculoskeletal health questionnaire in their study and concluded that the use of a prosthesis was not associated with any clinically relevant difference in the scores. They did however report that the "PedsQL results showed a significantly higher average score on the School Functioning Scale in the Psychosocial Health Domain for prosthesis wearers compared with non-wearers (p < 0.001)". 48 The report did not indicate if the type of prosthesis had been considered to have had any influence.
Studies to date therefore suggest that children with unilateral, upper limb deficiencies are as well adjusted as their able-bodied peers. However, there are no amputee-specific assessment tools available for testing and it is questioned whether the generic ones in use are sensitive enough to be useful for this population. Children with higher levels of limb deficiency have not been studied.
The issue of acceptance/rejection has been and continues to be a major focus of interest. 7, 13, 16, 17, 19, 21, 24, 25, 27, 29, 32, 62 to 66 Individual results are variable and often unpredictable. Some children will become full-time users and report feeling incapacitated when their device is not available to them. A few will insist on having a prosthesis but only use it passively or for limited but specific purposes. Some will be very good users for many years and then suddenly discard it. How then do we decide if the myoelectric fitting has been of value, at what points in the child's development should this determination be made and whose perspectives do we need to be most concerned about?
Biddis and Chau published the results of an extensive review of the literature on upper limb prosthetic use and abandonment in 2007 21 and reported that mean rejection rates were 45% for body-powered and 35% for myoelectric in children and significantly lower for adults (26% and 23% respectively). A wide range of variance was noted. Rejection and subsequent non-use of any prosthesis was reported for approximately one out of five individuals.
The duration of follow-up was also identified as a critical factor. With increased experience in this practice many clinics, including our own, now report seeing a pattern of increased discontinuation of use associated with age. Our longitudinal results for 135 children fitted since 1989 (a period of uniform fitting approach/ technology) show that the prostheses were well accepted during the childhood years but then started to rapidly decline as the children reached adolescence. This particular cohort is just entering their twenties so it will be important to continue to follow them to see if any of the individuals who abandoned use return to prosthetic wear as they start to encounter new vocational needs or experience overuse problems of the sound limb. Biddis and Chau concluded that "prosthetic acceptance and rejection was a complex issue dependent on a number of personal, contextual and technological factors". 21 They suggested that the available literature was inadequate for comprehensive understanding of these factors, particularly in regards to long term acceptance, and recommended that future research needed to involve multivariate studies and the use of standardized outcome measures.
Is it worthwhile then?
It has become apparent that there is no simple way to judge and that opinion is likely to differ according to the varied perspective of the professional, child, parent or funding agency.
From the perspective of the professionals, not only do we not have consensus but we have no common criteria as to what are considered acceptable or successful outcomes. Some authors have focused on the hours a device is worn with greater wear time equating with greater success. As a result, an individual that wears the prosthesis full-time but only uses it passively might be considered a success by one clinic while an occasional, but specific-use wearer might be considered to have a poor outcome by another clinic. One might also question how many years an individual needs to have worn a device for it to have been considered of value to have fitted them?
Little is known from the child's perspective as to why some children become life long prosthetic users while others discontinue use. Qualitative research approaches, involving individuals that have had experience as prosthetic users, both as children and as adults, could further our understanding of the contributing factors and help us to develop better selection processes and interventions in the future. Parents generally express a preference, based on appearance, for the myoelectric prosthesis when given an option. Many also say that it is important to them, as parents, to know that they have tried to obtain the most up to date technology for their son or daughter. It is not surprising then that the majority of parents support the practice of myoelectric fitting. Finally, we should not underestimate the benefit that the myoelectric experience may provide in the childhood years. A prosthesis that was rejected could still have been of considerable value to the child during the time it was used. 27, 29 For example, it may have made it easier for a child to learn how to ride a bicycle or tie their shoelaces independently at school. The prosthesis may also have offered some social benefit – eased integration and enhanced self image.
A child's interests change over time and there is now growing support for the practice of offering a choice or use of multiple devices to help the child fully participate in all aspects of daily life. 8, 19, 21, 65, 67 Fortunately for our children, the CHAMP organization has always supported this philosophy and has provided the encouragement and funding to allow them to pursue a wide variety of interests. We also need to remember that there are a significant number of individuals who do choose to wear their prostheses long term. For them, the prosthesis is greatly valued as an integral part of their body image and function.
It is equally important to recognize that there are limitations to today's technology and that children may be discouraged from using a prosthesis if it limits their ability to participate in normal childhood activities. Problems such as weight, glove breakdown and sand and water restrictions have long been identified but gone unresolved and we can only hope that some of today's research activity will eventually lead to improvements in the technology and new promise for children in the future.
Does the literature or our collective experience provide sufficient evidence to justify or condemn the practice of myoelectric fitting? It would appear not! The variation in practice, population, expertise and lack of standardized evaluation make it almost impossible to draw any definitive conclusions. The problem with most of the literature is that we have all tended to look at our experiences retrospectively – collected some data as we have gone along and then tried to analyze it in the form of a program evaluation instead of doing it prospectively and designing a study to specifically address the issues. The Shriners' Study is a good start and it is hoped that others will follow their example in planning systematic, multidimensional evaluation for longer periods of time. We do require evidence from more than one study and clinical population. There is also a need for collective and collaborative investigation to obtain sufficient data to determine significance and to compare practices.
In the meantime, I believe that a myoelectric prosthesis, while far from perfect, does offer an acceptable combination of function and cosmesis for young children and that it may have an influence on the child's early physical and psychological development. Although individual outcome cannot be predicted with any certainty, it is possible to identify some of the factors that are likely to influence results. Cited indicators include family commitment, age of first fitting, degree of limb deficiency, experience/ expertise of the prosthetic team, consistency of prosthetic wear, product functionality and reliability and service accessibility. Successful outcome is most likely when all the influencing factors are positive. There is a great need for further study, continued research and development and solutions sought to reduce the costs of fitting.
I would like to express my appreciation to Jan Andrysek, PEng, PhD, Lisa Artero, BSc (OT), Shane Glasford, CP (c) , Greg Vanden Kroonenberg, Multimedia Specialist and Virgina Wright, PT, PhD for their assistance with this presentation and to extend a special note of thanks to the individuals and families who graciously gave me permission to use their photographic material.
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