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Survey of Upper-Extremity Prosthesis Users in Sweden and the United Kingdom

Kyberd, Peter J. PhD; Wartenberg, Constanze PhD; Sandsjö, Leif PhD; Jönsson, Stewe CPO; Gow, David BSc; Frid, Joakim MSc; Almström, Christian PhD; Sperling, Lena PhD

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JPO Journal of Prosthetics and Orthotics: April 2007 - Volume 19 - Issue 2 - p 55-62
doi: 10.1097/JPO.0b013e3180459df6
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Essential to all aspects of the supply of equipment and services is the monitoring of the end users’ satisfaction. This is especially true for health care, whether it is partly or wholly publicly funded. The survey reported here is part of a larger program funded by the European Union (EU) aimed at improving the quality of life and provision for the elderly (Technology for the Integration of the Disabled and Elderly, TIDE). Specifically, ToMPAW (Totally Modular Prosthetic Arm with high Workability, DE420) aimed to improve the design and application of upper-limb prostheses.1 This project builds on the experience and technology of three of the leading research programs in Western Europe conducted during the last 30 years.2–5

BACKGROUND

THE ToMPAW PROJECT

Developed in Sweden during the 1970s, the SVEN hand project aimed to produce a hand and wrist system controlled by a pattern recognition system that used the operators’ impressions of their phantom limbs to drive the device. This led to the clinical use of the hand in Sweden.2,6

The Edinburgh arm contributed to the development of the concept of extended physiological proprioception to control the arm in a manner with more appropriate feedback than any other system. Later work by Gow et al.3 led to the world’s first practical powered-shoulder system, which is currently the only one used in the field by leading research groups.7,8

The Southampton Hand embodied the concept of hierarchical control, where the controller uses the information from sensors within and outside the hand to decide on the most appropriate grip shape and force to maintain a stable grasp on a particular object.4,5,9,10 Versions of the hand have been used in the field for years, and the idea of hierarchical control—where the prosthesis responds to the environment of the device and the actions of the users—is now being adopted in upper- and lower-limb prostheses.

Specifically, this survey adds to the knowledge obtained during an earlier EU-funded project, the details of which are reported by Kyberd and colleagues.5,11

SURVEY

The survey was used in the process of creating the specification of the ToMPAW device. It could then be used as a point of reference for the progress of the arm development. It has a more general utility in supplying data concerning the interests and concerns of the population in two countries, adding to and updating previous work and allowing the context of different cultural backgrounds to be observed.

The study was designed to include a heterogeneous group of prosthesis users from three fitting centers in two European countries (Sweden and Great Britain). With a focus on the users’ viewpoints, the survey used both closed and open questions, enabling participants to name aspects of most concern. Results are categorized by the types of prostheses used. The closed questions were from an earlier survey,5 so some comparisons could be made with the earlier work.

Although a number of projects collect knowledge about the user population and its wishes, many are restricted to single sites or single countries.11–14 This study included three centers in two European countries, which allows for comparison of the different perspectives between the countries.

METHODS

The survey was conducted at three fitting centers (see Appendix). A questionnaire was mailed to the selected participants. If no response was forthcoming within 2 weeks, one reminder was sent.

QUESTIONNAIRE

The questionnaire consisted of four sections:

  1. An introductory letter outlining the background and main purpose of the survey
  2. Ten closed questions concerning the type(s) of prostheses used as well as the type and frequency of usage.5
  3. Questions pertaining to degree of satisfaction with qualities of the prosthesis used most frequently, including comfort, functionality, and daily usage. “Functionality” here is restricted to manipulative functionality. Other nonmanipulative aspects of functionality (i.e., holding and stabilizing objects) that are included in Fraser’s analysis of actions performed with a prosthesis13 are not included. Satisfaction was rated on a 10-point scale ranging from “very satisfied” (10) to “very dissatisfied” (1). Respondents were asked to nominate three improvements they would most like to see. Space was provided for inclusion of additional comments.
  4. Four questions on general demographic and epidemiological information about the participants.

Inclusion criteria:

  • Unilateral upper-extremity loss
  • User of an upper-extremity prosthesis
  • No additional impairments relevant for the use of the prosthesis
  • Older than 16 years of age
  • Attendee of one of the limb-fitting centers

The subjects were selected if they fit the criteria and were considered “active users” by their local centers (i.e., they had attended the center within the last 3 years11). Questionnaires were sent, the responses were collected, and participants were provided with a summary of the results of the study, ensuring feedback to the user group (while maintaining anonymity).

RESULTS

Of 156 users contacted, 117 (75%) responded. Some general information about the nonrespondents was available at the fitting centers in Göteborg and Edinburgh, showing no particular bias in age, gender, or prosthesis type in the nonrespondents.

Four respondents reported they do not wear their prostheses and thus were excluded from additional analysis. The distribution of the remaining 113 participants with respect to the level of loss, the principle type of prosthesis used, and subject gender and age is presented in Table 1.

Table 1
Table 1:
Distribution of the survey sample regarding type of limb loss, principle type of prosthesis, and subject gender and age

PROSTHESIS TYPE

Cosmetic prostheses are the most common type of artificial limb reported for all different levels of limb loss. Among the respondents, 28% use more than one type of prosthesis. The use of different types of prostheses is more common among users who wear electric prostheses more frequently (40%) than among users whose main prosthesis is a cosmetic device (20%).

USE

Most participants (76%) wore their prostheses more than 8 hours daily, with 46% reporting a wear time of more than 12 hours/day. This includes using the prosthesis during work (73%), sports (60%), and for driving (62%). A rather small group of 10 respondents (9%) use their prostheses only occasionally and for a shorter duration. Of these occasional users, four had a cosmetic prosthesis and four an electric prosthesis. This is in the upper end of previously reported ranges (58%–77%).11,15–17

SATISFACTION/DISSATISFACTION WITH PROSTHESES

To assess users’ views of their prostheses in detail, satisfaction was rated using 17 qualities of comfort, functionality, and daily use of the prosthesis. Ratings were expressed on a 10-point scale. Results from these questions are shown in Figure 1.

Figure 1.
Figure 1.:
Rating of the respondents’ satisfaction for 17 qualities using levels of comfort, functionality, and daily use of the prosthesis as a guide. Ratings were expressed on a 10-point scale, ranging from “very dissatisfied” (1) to “very satisfied” (10). Distribution is mean ± 25%.

To aid comparison of results, each respondent’s individual rating was standardized relative to the mean and standard deviation of all their scores. Thus, a standardized value of 0 corresponds to the personal mean rating, and a value of 1 corresponds to one standard deviation above the personal mean. In this way, each person has the same overall weight in the analysis. These results are shown in Figure 2.

Figure 2.
Figure 2.:
The areas of improvement identified by the respondents analyzed as a percentage of the number of respondents for electric and cosmetic prostheses.

COMPARISON OF USERS OF ELECTRIC AND COSMETIC PROSTHESES

This report concentrates on a comparison between cosmetic and electric prostheses because the choice of the hand prosthesis user is of primary concern to both users and providers.

Mean ratings of satisfaction/dissatisfaction between the two groups did not differ greatly. Taking all qualities into account, the mean overall satisfaction of users of cosmetic prostheses is 6.9, whereas the corresponding value for users of electric prostheses is 6.7. The difference is not statistically significant. However, the detailed profiles (Figure 2) show that the groups are concerned about different aspects of their prostheses.

LEVEL OF ABSENCE

If the standardized satisfaction ratings are broken down further into transhumeral and transradial categories, there are few discernible differences. Not surprisingly, there are few significant differences among the users of cosmetic arms, although the strength of a transradial fitting is seen as positive, and the public perception of the transhumeral device is more positively felt (t-test, p < 0.1).

Although there is less general agreement between the groups of transradial and transhumeral absences in the users of electrically powered arms, there was less variation in any particular category. The ability to generate force in the transhumeral systems was seen as positive (p < 0.1). Ease of donning and doffing was a notable consideration for the users of shorter prostheses (p < 0.2).

AREAS OF MOST CONCERN

To provide the users a place for an unstructured response, one question was left open: In what way would you like to improve your prosthesis? Participants could name as many as three aspects. For comparison, the three most frequently identified improvements were grouped into the same categories in the closed questions. The degree of correlation between the open and closed responses was high. There was just one new area identified in the closed questions: the range of movement of the hand/arm. In addition, one area (donning and doffing) was closely related to the fit of the socket, so these were combined in the analysis.

Table 2 summarizes central improvements participants named as relevant. The frequency of the identified areas of improvement was analyzed as a percentage of the number of respondents in the two categories of electric and cosmetic prostheses (Figure 3).

Table 2
Table 2:
Features identified as the primary areas for improvement
Figure 3.
Figure 3.:
Areas identified for improvement by users of electric and cosmetic prostheses. Values are expressed as percentages of the number of respondents in each group, electric (30) and cosmetic (68). Because each person could name as many as three different improvements, the percentages sum to greater than 100%.

RATINGS OF OCCASIONAL USERS

Of special interest are ratings of people who used their prosthesis only occasionally. The four users of electric prostheses who report only limited use expressed dissatisfaction with aspects of functionality. They also showed considerable dissatisfaction with the weight of the device and the fit of the socket.

The four participants who only occasionally used cosmetic prostheses gave especially low ratings to the fit of the socket and aspects of their prostheses’ functionality. This is consistent with the findings of other studies.11,17,18

DISCUSSION

The response rate of 75% is well above the range of typical values (10%–50%),19 confirming the choices made in the design of the questionnaire.

It is difficult to judge how representative the sample used in the study is because of a lack of detailed national statistics on the population of prosthesis users. Differentiated reports on representative samples are rarely made. Representative samples that are reported often do not give detailed descriptions of the type of prosthesis used. Fitting centers can differ considerably in the populations they treat; the information representative for a certain fitting center does not imply the same representation for the national or international population. The centers participating in this survey were selected for practical reasons rather than because they were known to be typical of that country. However, the main aim of this survey was to identify the opinions and experiences of a wide range of prosthesis users and the distribution of participants.

The question of why a considerable number of people with upper-limb losses choose not to use a prosthesis was not addressed in this survey. This question needs a different form of survey and questionnaire, similar to that presented in Kejlaa.16

POPULATION

In the entire survey population, the use of cosmetic prostheses is most common. Electric prostheses are used less, and their use is limited to specific forms of loss. In comparison with other studies,16 there was a low proportion of users of mechanical body-powered prostheses in this survey.

Currently, the use of purely electric prostheses presents an alternative in cases in which the loss is midradius or below. Although some studies have pointed out considerable advantages in the use of electric prostheses,18 these are still not used as commonly as cosmetic prostheses.

The population in Göteborg has a greater number of electric prostheses users than do centers in the United Kingdom. This bias may be attributable to early users in Scotland being sent to selected centers5 and the Swedish emphasis in fitting powered prostheses early, which leads to greater familiarity20 and may increase long-term acceptance.21

The mean and variance of the ratings of each individual in 17 qualities was analyzed. This showed individuals’ mean values ranged from 3.5 to 10 (the latter giving the same rating of 10 for all dimensions). The standard deviation of an individual’s ratings ranged from 0 (a person giving the same rating to all dimensions) to 3.3. In general, the profile in Figure 1 indicates that users are quite satisfied with the prostheses they use most (none of the mean values is below 5, which is the value corresponding to the neutral point on the scale). This is not surprising because the respondents are those who use their prostheses a great deal and thus are expected to be reasonably satisfied with them. In addition, other studies have shown that, in general, those who do their devices do so for many hours a day11,17,18; they are shown to be committed users (a possible result of the selection process).

The different responses can be attributable to real differences in satisfaction, but there is some risk that they may, in part, be caused by individual differences in the way scales and ratings are interpreted (e.g., because of different response sets and reference systems). Response sets imply that a person limits the usage of the rating scale to certain parts of the answer (e.g. the positive or neutral area).

The effect of different reference frames can be that one person judges a prosthesis in comparison with the natural hand, whereas another person refers to experiences with other prostheses. Thus, the results will be very different. Tversky22 presents the importance of context for quality ratings.

One aim of this survey was to identify the improvements seen as most important to the users; thus, the analysis of the aspects that are perceived as least satisfactory was key. Even users who expressed a generally high level of satisfaction usefully contributed information as to which aspects are less satisfactory.

Figure 2 presents profiles for the groups who mainly use electric or cosmetic prostheses. However, a considerable number of users of cosmetic prostheses included functionality in their responses. Fraser17 points out that even cosmetic prostheses often are actively used in daily life. One indication to the active use of “passive” cosmetic prostheses is the frequency of their need for repair and the failures that occur.

Some results are exactly as one might predict from circumstances: cosmetic limb users are least satisfied with the glove, whereas electric prosthesis users express most dissatisfaction with aspects of functionality. Both groups are least satisfied with aspects that can be seen as a central quality of the kind of prosthesis they use.

The ratings of cable hand users (a subgroup of 7 people subsumed in the group “other”) have profiles similar to those of electric prosthesis users. They are least satisfied with the glove and with aspects of functionality. Cable hand users express most satisfaction with maintenance, donning and doffing, fit of the socket, and the “prosthesis as part of oneself.”

The high degree of correlation between the open comments and the dimensions in the closed questions is encouraging and may be seen as an indicator for the relevance of the 17 dimensions identifying the topics of most concern. An alternative explanation is that the correlation may be attributable to the ranking of 17 aspects causing users to focus on those topics, biasing even the open questions.

Figure 3 shows that there are considerable differences between users of cosmetic and electric prostheses when asked to name the three improvements most important to them.

First, users of cosmetic prostheses could not name as many improvements as users of electric prostheses, having fewer categories on which to comment. The comments users of cosmetic prostheses most often made were concerned with aspects of appearance, but it should be noted that users of cosmetic prostheses also cite concern about improvements of movement and grip functionality.

Users of electric prostheses comment mostly on aspects of functionality and range of movement, but they also expressed concern about appearance and reliability. Other qualities, such as weight, fit of socket, and the prosthesis in daily use, are identified with similar frequency in both groups. The matter of prosthesis weight is most telling, being a concern even with the lighter prostheses.

SATISFACTION

Although the questions generally resulted in high satisfaction ratings for all active users, the high proportion of nonusers known from other studies suggests improvements in current prostheses are needed. In this context, it is important to identify the improvements of most concern. The empirical results of the current survey show that users of electric prostheses were most concerned about aspects of functionality. Users of electric prostheses and users of cosmetic prostheses expressed a need for improved appearance of their prostheses. Interviews with prosthetists carried out for the ToMPAW project show that these concerns of users are well known to people working in the field of upper-limb prosthetics.

An interesting observation in this survey is that different centers seem to favor the provision of one kind of prosthesis. It can be assumed that this is attributable not only to the specialization of a certain population treated at the limb fitting centers but also to the different philosophies held at the centers. This reflects a different attitude than the reasoning expressed by Stephens et al.23 that different people prefer different types of prostheses and that experiences with different prostheses are an important precondition for a user’s choice of a prosthesis optimal for his/her individual needs.

Considering these preferences and needs that inevitably will change with time, the development of a modular prosthesis that allows for the exchange of modules and the adjustment of control strategies within a more stable framework would assist in maintaining a consistent but reactive provision.1

CONTEXT

This survey is one of a number reported in the literature. It is only by comparison that there is a possibility of obtaining a better overall impression of the state of the field. One recent exception is the survey conducted by Atkins et al.12 The numbers involved are impressive (more than 2,000 respondents to the short questionnaire). The authors could tailor the survey and subdivide into different user groupings (body power, electric and bilateral users) without diluting the results. The conclusions from that survey are broadly the same as those from the current survey, indicating the interests and needs of the European users are similar to those of the Americans questioned.

The primary problem with the survey from a European perspective was that the questions concerned the perceived cost of the device. Because both the United Kingdom and Sweden have state funding of prostheses supply, the user’s perception is likely to be bound up with their perceived service from the state health system. As the requirements for the improvement of prosthetic technology, they identify the factors that have been incorporated into advanced prosthetics systems during the past decade, especially those embodied in the Southampton Hand and the Edinburgh arm systems.24,25

As with many surveys, the responding groups were self-selecting, and overwhelmingly they were frequent users of their devices. This cannot address reasons others do not use their prostheses, but it is the opinion of people who regularly wear their hands and arms. This opinion is that prostheses are sufficiently functional and that the users are sufficiently satisfied with the result to continue using them. These facts are important to stress at this time when providers and payers alike are questioning how best to spend money on this population.

CONCLUSIONS

The survey of users in centers in two different countries within the European Union shows common concerns and problems in both countries. The purpose of this survey was to assist in the design process of a new generation of a prosthetic arm system. The users of electric hands are concerned with function; cosmetic users are concerned with appearance. Individuals who do use their prostheses tend to do so all day.

RECOMMENDATIONS

Along with the understandable desires for lighter, more reliable, and more anthropomorphic arms, the qualities identified from the survey that particularly informed the design choices of the ToMPAW system were:

  • Quiet operation of joints without the sound of brakes being applied or removed.
  • A wide range of grip shapes and good control of the grip force (e.g., not too high an initial grip force).
  • Reliable operation, free from breakdowns and interference from electrical noise.
  • Intuitive control.

These recommendations were taken forward to the engineering phase of the ToMPAW project.1,25

ACKNOWLEDGMENTS

The authors thank the participants of the study for their time and the detailed answers to the questionnaire. The authors also thank the fitting centers for their contribution in organization and data collection. This survey was conducted as part of the ToMPAW project (DE 420), funded by the Telematics Applications Programme of the European Commission.

APPENDIX

CHARACTERIZATION OF FITTING CENTERS

The three centers involved in the survey were:

Edinburgh, Scotland. Participants at the fitting center in Edinburgh are younger and include a high proportion of women. In comparison, many users of cosmetic prostheses participated.

Göteborg, Sweden: Compared with the other centers, Göteborg has a high proportion of users of electrical prostheses. Participants at this center are slightly older and have worn prostheses for a longer time than respondents from the other centers.

Stockholm, Sweden: The participants at the Stockholm center include comparatively more patients with limb loss above the elbow (55.2%). The users of cosmetic prostheses predominate in this sample.

REFERENCES

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3. Gow DJ, Dick TD, Draper ERC, et al. The physiologically appropriate control of an electrically powered hand prosthesis. Presented at: International Society of Prosthetics and Orthotics 4th World Congress; September 5, 1983; London, United Kingdom, p. 43.
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21. Heger H, Millstein S, Hunter GA. Electrically powered prostheses for the adult with an upper limb amputation. J Bone Joint Surg Br 1985;67(2):278–281.
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Keywords:

artificial arms; control; design; myoelectric control; prosthetic limbs; survey

© 2007 American Academy of Orthotists & Prosthetists