Comparison of Adept Terminal Device to Mechanical Hand Terminal Device for Bimanual Activities in Children

MARY LOCAST OTR/L, SHARON SHAPIRO OTR/L JEFFREY ACKMAN, MD


Shriners Hospital in Chicago follows approximately 30 children each week in its prosthetic clinic with an equal distribution of upper and lower extremity amputees. This study was conducted from 11/90 to 12/91 and presented at the ACPOC conference in St. Louis in June, 1992.

Due to the increasing knowledge and technology in the field of prosthetics, the number of options available to children and adults with below-elbow amputations continue to increase, both in terms of prosthetic componentry and terminal device (TD) selection. The need for ongoing research in the comparison of these options has therefore become evident.

Previous studies have been conducted comparing the effectiveness of the myoelectric prosthesis with the body powered prosthesis using the hook TD and comparing the hook TD to the Adept.

The mechanical hand has also been compared to the myoelectric prosthesis and found to perform equally well for most functional tasks. In our clinic we were finding that many of our children were opting for the mechanical hand over the hook or Adept because of its added cosmetic features. While we were fairly confident about the functions and benefits of the Adept, we were unsure as to whether the mechanical hand was offering the children a functional alternative.

This study was undertaken to determine if there is a significant difference in the use of the Adept and the mechanical hand for functional bimanual activities performed by children using conventional below elbow prostheses.

Subjects

Six children were chosen to participate in this study. We chose only those who had the Adept and mechanical hand to use interchangeably. All subjects had to have both TDs for at least 6 months prior to participation in the study. Four of the subjects used Boch mechanical hands and two had Steeper hands. Four of the subjects had the standard TRS Adept terminal device and two had the TRS Grip II terminal device. The subjects had to be old enough so that they were able to perform the majority of tasks on the evaluation.

Specific breakdown was as follows:

  • Age range: 3 + 11 years to 15 + 6 years.
  • 5/6 subjects actually wore TDs interchangeably.
  • 4 subjects wore Adept more often than mechanical hand.
  • 2 subjects wore mechanical hand more often than Adept.

Research Design

Each subject was given a subjective questionnaire regarding their overall preference for a TD. On this questionnaire they were also asked to choose between the Adept and mechanical hand based on ten performance factors discussed later in the article. Those children under the age of seven were assisted with filling out the questionnaires by a parent. The subjects were then timed and videotaped performing 10 standardized bimanual activities using each TD. For the purpose of this study, time was used as a measure of functional skill.

To eliminate the practice effect, the subjects were randomly selected to begin the testing with either the Adept or the mechanical hand. The activities were standardized as to the materials used, set-up, and instructions provided in order to insure consistency of the evaluation (see Appendix A.).

Subjective Findings

Based on the results of the questionnaires, we found that four subjects stated a preference for the Adept and two subjects stated a preference for the mechanical hand. When the subjects were asked to explain their preference, those who chose the Adept stated that it is useful for more things, easy to use, more powerful and easier to keep clean. The only reason cited by those preferring the mechanical hand was that it looked better.

Specific activities listed as being easier with the Adept were: bike riding, climbing and tying shoes. Activities found to be easier with the mechanical hand were: holding sheets of paper, lifting books, locking on objects and wearing gloves.

The subjects were also asked to choose between the Adept and the mechanical hand on ten performance factors. These factors are:

  1. Appearance
  2. Other peoples' perceptions of the TDs
  3. Weight of the prostheses
  4. Ease of opening
  5. Ease of closing
  6. Power of grip
  7. Ability to maintain grip on objects
  8. Ability to grasp a variety of objects
  9. Ability to see objects while grasping
  10. Need for repair or part replacement.

All subjects preferred the mechanical hand for its appearance and for what they felt were other people's perception of the TD. The majority of subjects chose the Adept for all other performance factors (see Table 1 ). When asked about need for repair, the subjects either had no preference or preferred the mechanical hand. They stated that the Adept required more frequent repairs whereas the most common complaint on the mechanical hand was the frequent need for new gloves.

Objective Findings

The objective performance evaluation included:

  • putting on glove
  • zipping a coat playing cards transferring pegs cutting a circle
  • taking money out of a wallet
  • putting toothpaste on a toothbrush
  • putting a bandaid on a doll
  • unscrewing a bottle top
  • opening a candy wrapper

All of these activities were timed and data were analyzed using chi-square and student T-test. When the data were broken down by subject performance, we found that four of the six subjects performed faster on the majority of the activities when they used the Adept. Two of the six subjects performed faster on the majority of activities when using the mechanical hand. Two of the six subjects could not complete all of the tasks because of their young age (see Table 2 ). When analyzing these results, the only commonality we found was that the two subjects who performed better with the mechanical hand were very active teenage boys. The other four subjects were all under 10 years of age. When the data was broken down by activity (see Table 3 ), we found that six activities were done faster by the majority of subjects using the Adept. They are:

  1. putting on gloves
  2. taking money out of a wallet
  3. pegboard activity
  4. putting a bandaid on a doll
  5. unscrewing a bottle
  6. playing cards

The two activities that were done faster with the mechanical hand are:

  1. cutting a circle and
  2. opening a candy wrapper.

Subjective Findings Vs. Objective Findings

When comparing the subjective preference of the children with their actual performance, we found it interesting that four of the six subjects stated a preference for one TD, but did functionally better or faster using the opposite TD. We noted that the two subjects who stated a preference for the Adept, but performed faster using the mechanical hand were boys over the age of 13. The two subjects who stated a preference for the mechanical hand, but who did better with the Adept were young girls under the age of seven. From this information we could speculate that for these young girls, appearance was a more important factor than was function. Conversely, the older boys may have felt that the Adept was the more appropriate TD for their active lifestyles.

Conclusion

In summary, we found that four of the six subjects performed better on the majority of the ten bimanual activities using the Adept. Because of our small sample size, however, we were unable to demonstrate statistically that the Adept is the more functional TD. We also found that subjective preference and actual performance are not necessarily related to each other. It should not be assumed that a child will prefer a TD that is most efficient for him or her.

Our data analysis suggests that the strength and age of a child plays a large part in the child's ability to operate TDs. The older boys seemed to have less of a discrepancy in their performances using the Adept versus the mechanical hand. The amount of effort involved in operating the mechanical hand for the very young child continues to be a problem. Finally, our data suggests that function itself is not always the most important factor for the child. We as clinicians, have to be aware of the needs and priorities of each child and their families before we recommend a specific terminal device.

Shriners Hospitals for Crippled Children 2211 N. Oakpark Ave. Chicago, Il. 60635-3392