Clinical application of simulators when learning to use upper limb prostheses

People with an upper extremity amputation often choose to have fitted a
prosthesis to restore the functionality for as best as possible. About 30% of
upper extremity amputees do not use their prosthesis at all due to a low degree
of functional use (Biddiss & Chau, 2007; Dudkiewicz et al., 2004; Kyberd et
al., 1998; Plettenburg, 2002). The functional use of upper extremity prostheses
is not only determined by its function, the technical possibilities, but also
by its functionality, the way the amputee is able to handle the prosthesis. The
proposed innovation intends to enhance the functionality to improve the use of
prostheses and with that to make rehabilitation more successful.
It is found that it is of great importance to start to train in the first month
after the amputation to achieve maximum success in prosthetic use (Atkins,
1992; Dakpa & Heger, 1997; Gaine et al., 1997). But in this period often the
wounds are not healed yet and the prosthesis is not finished. To be able to
start to train within these weeks, a prosthetic simulator on the unaffected
limb could be used. With an upper limb prosthetic simulator training can start
with the unaffected hand. Because of a transfer of learning effect a higher
starting level can be reached at the time the prosthetic training is started on
the amputated side.
A prosthesis simulator is an upper limb prosthesis that can be applied to a
sound arm. With the prosthesis simulator the effects of a myo-electric
prosthesis can be mimicked. In myo-electric prostheses the hand is opened and
closed by a motor that is activated by electrical signals produced by the
muscles. The simulator can be used in the same way. It is applied over the arm,
where the prosthetic hand is placed in front of the sound hand (see figure 1 of
the research protocol). Therefore the training with the simulator is comparable.
In literature it is shown that motor skills learned with one arm are effecting
the execution of the same skills of the other arm. (Hicks et al., 1983; Karni
et al., 1998; Kumar & Mandal, 2005; Lee et al., 2010; Mier & Petersen, 2006;
Pereira et al., 2011). This transfer of learning effect can be used in the
rehabilitation after an amputation. After training the unaffected hand with the
simulator it is expected that the affected hand has a higher starting level and
that the skills are improving faster. In this way the sound arm can be used to
train the prosthesis simulator, while improvement of the other arm is expected
due to the transfer of learning effects.

The objective of this study is to determine the application of the prosthesis
simulators and the bimanual transfer effects in the existing rehabilitation
programs for patients who will obtain an upper limb prosthesis.

At first it needs to be revealed if transfer of learning effects are presented
in the use of a prosthetic simulator. Bimanual transfer effects are found in
several simple and some complex tasks ((Hicks et al., 1983; Karni et al., 1998;
Kumar & Mandal, 2005; Lee et al., 2010; Mier & Petersen, 2006; Pereira et al.,
2011; Weeks et al., 2003). Although it is has never been applied to a
myo-electric prosthetic simulator. Therefore, our first goal is to analyze the
transfer effects in healthy adults after training with the simulator.

The next step is to determine if the transfer effects are not only presented in
the usage of the prosthesis simulators, but also in the real prostheses. For
the rehabilitation it is of great importance to establish if the effects found
in prosthesis simulators are generalizable to the prostheses. Here for, first
it is analyzed if experienced prosthetic users are more skillful in using the
prosthesis simulator on their sound arm then the able-bodied participants.
This effect is expected because of the transfer effects from the well trained
amputated limb towards the prosthesis simulator on the sound arm. As far as we
know it is never described how prosthesis users execute activities with a tool
the unaffected arm.

Finally, it will be revealed if the transfer effects are presented in patients
who will obtain their first myo-electric prosthesis. We expect that patients
who will train with a prosthesis simulator develop skills to be able to perform
better using the prosthesis once it is finished. This means that patients can
start to train earlier in the rehabilitation process, what can lead to more
successful use of the prosthesis. If the transfer effects are determined, this
study results will have important consequences for the early rehabilitation
after an upper limb amputation.

Four experiments, each with their own design are presented (See table 1-4 from
the research protocol). In all experiments the same tests and training are
used.

The goal of the first experiment is to test if transfer of learning effects are
measurable in able-bodied adults using the simulator. The participants in the
experimental group learn to use the simulator on one hand (training hand) while
transfer effects are measured on the other (test hand). The control group only
performs the tests, to analyze the added effects of the training.
The learning is divided over five days to mimic a real learning process in
rehabilitation. It is found that the distribution of the training over more
days is important for the consolidation of learning (Park & Shea, 2003;
Penhune, 2004; Savion-Lemieux & Penhune, 2005; Siengsukon & Boyd, 2009). As
such, training on several days is also important for the transfer of learning.
Pereira (2011) found improvement in dexterity skills in the untrained limb
after practicing with low intensity (20 min a day) spread over 5 days.
We will use the Southampton Hand Assessment Procedure (SHAP) for training
(Metcalf, 2008). With the SHAP we can offer a standardized training procedure
with sufficient variation in tasks (26) in order to be able to promote strong
learning (Schmidt 1999). This variability will improve skill acquisition,
retention and transfer (Stokes 2008). Half of the patients will train their
dominant hand and half will train their non-dominant hand.
A pretest, posttest and retention test will be performed to determine if there
are learning effects and if these will remain. Only when there are significant
results we will continue with the other experiments.

In the third experiment experienced adult and paediatric prosthetic users will
perform the same tests as the able-bodied participants, with the simulator on
the sound arm. With the results of this experiment we will reveal general
principles of transfer of learning in real prosthetic use. It is expected that
while using the prosthesis there is a bimanual transfer effect. As such, we
expect it will be easier for experienced prosthesis users to execute the tasks
with the simulator. As far as we know it has never been reported before how a
prosthetic user performs activities with a tool on the sound hand.

The last part aimes to reveal generalization of the findings to the patients
who intend to wear a myo-electric prosthesis for the first time. The design is
the same as in experiment 1, except that the pretest will not be executed
because the prosthesis will not be available at that time.

See the research protocol.

Execution of the tests from the SHAP with the prosthesis simulator does not
have any risks.