The goal of this clinical trial is to systematically evaluate whether or not two commonly held fundamental assumptions for pattern recognition control translates to functional performance when tested on individuals aged 18 years or older with upper limb absence at the transradial level while wearing a physical prosthesis.
The specific aims of this study are:
1. To evaluate the effect of changing untargeted myoelectric channel count on the functional performance of transradial prosthesis users wearing a fully functional prosthesis via functional outcomes measures such as the Box and Blocks test. 2. To evaluate the effect of changing myoelectric channel targeting of a fixed number of myoelectric channels on the functional performance of transradial prosthesis users wearing a fully functional prosthesis via functional outcomes measures such as the Box and Blocks test.
Researchers will perform a randomized crossover study to compare system configurations with different number of sensor channels and with various strategies for sensor placement on the limb. Participants will be assigned to a random test sequence that includes the following four different EMG channel conditions:
Condition A: 4 untargeted channels Condition B: 8 untargeted channels Condition C: Up to 16 untargeted channels Condition D: 8 targeted channels
Researchers will evaluate the effects of changing myoelectric channel counts on the functional prosthesis performance of individuals with transradial limb loss via functional outcome measures.
Participants will:
* Attend up to 5 in-lab sessions that are expected to last 4 hours. * Conduct site visits every 1-2 weeks to complete functional and self reported outcome measures with each condition. * Play virtual games with the Coapt Cuff for 15 minutes a day, 3 days a week in between visits.
Unilateral transradial level limb absence
Current or past user of myo-electric controlled prostheses
Six months or more post-amputation
Have adequate limb length such that a wrist rotation device can fit in the check socket
Significant new injury that would prevent use of a prosthesis: The ability to consistently wear a prosthesis and perform activities of daily living and specific performance tasks is necessary to evaluate the relative benefits of the interventions.
Cognitive impairment sufficient to adversely affect understanding of or compliance with study requirements, ability to communicate experiences, or ability to give informed consent: The ability to understand and comply with requirements of the study is essential for the study to generate useable, reliable data. The ability to obtain relevant user feedback through questionnaires and informal discussion adds significant value to this study.
Crossover
Experimental socket with 4 untargeted channels active
DeviceParticipants will utilize the experimental socket made with untargeted EMG channels. Untargeted sites will ideally be located by creating a band of electrode pairs at the largest muscular circumference distal to the elbow. Only 4 channels will be active during this condition.
Experimental socket with 8 untargeted channels active
DeviceParticipants will utilize the experimental socket made with untargeted EMG channels. Untargeted sites will ideally be located by creating a band of electrode pairs at the largest muscular circumference distal to the elbow. Only 8 channels will be active during this condition.
Experimental socket with up to 16 untargeted channels active
DeviceParticipants will utilize the experimental socket made with untargeted EMG channels. Untargeted sites will ideally be located by creating a band of electrode pairs at the largest muscular circumference distal to the elbow. All16 channels (or the maximum number of channels based on limb size) will be active during this condition.
Experimental socket with 8 targeted channels active
DeviceParticipants will utilize the experimental socket made with targeted EMG channels. This socket will follow Coapt's clinical instructions for targeted site location to identify and mark locations for 8 targeted EMG channels.
Coapt EMG Cuff
DeviceThis device is the commercially available Coapt EMG Cuff. This armband cuff with electrodes can be strapped onto the user's arm to connect with the Coapt app and play virtual games with their EMG signals.
The Assessment of Capacity for Myoelectric Control (ACMC)
The ACMC is a performance-based assessment where trained raters observe the user performing a task and rate their ability to control specific hand movements. These movements are rated on a 4-point scale, ranging from "not capable" to "spontaneously capable". 0 = Not capable. 1 = Sometimes capable, capacity not established. 2 = Capable on request. 3 = Spontaneously capable. The items comprising the ACMC describe different levels of difficulty of control of the myoelectric hand. The items are grouped into 4 categories: gripping, holding, releasing, and coordinating between hands. The task that will be done for our study is packing a suitcase for a weekend trip. A higher score corresponds with a greater ability to control a myoelectric hand. This assessment will be done for each condition, each of which will be tested in visits 2-5.
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