Regular prosthesis use by an individual with upper limb loss can help improve general well-being. Individuals who do not use their prosthesis report more significant functional disability and lower health-related quality of life. A significant proportion of individuals with upper limb loss report high levels of disuse or discontinued use of their prosthesis because of physical pain or psychological distress, perceptions that the device provides no functional benefit, undesirable aesthetics, and issues with fit, comfort, weight, or design of their prosthetic device. Being able to exert intuitive control over a device would theoretically pose a lower cognitive burden to the user, concomitantly increasing functional performance. This effect could bolster device use and satisfaction.
Pattern recognition controller (PRC) systems for upper limb prostheses are a replacement to conventional direct controller (DC) systems. For decades, two-site DC has been the primary method for controlling upper limb myoelectric prosthetic devices. The DC method involves recording surface electromyography (EMG) at two 'control sites', ideally an antagonistic muscle pair in the residual limb. Alternatively, PRC is an emerging approach to myoelectric control that can potentially address the key limitations of DC. PRC uses pattern classifiers to discern intended motions based on EMG signals recorded from multiple sites on the residual limb. PRC combines EMG signals captured from multiple electromyography sensors on the residual limb to determine control intent and subsequently translate that intent to the wrist and hand/terminal device unit, while DC relies on signal level from two sensors, with the dominant signal being translated into a movement intention to control the prosthesis. The PRC technique avoids the need to isolate muscle activations and non-intuitive triggers. PRC offers a potentially more natural and intuitive way to operate along a greater range of motion, as well as perform a larger number of hand grasps when compared to DC - particularly during tasks that are complex and require rapid switching between actions of the wrist and/or terminal device. PRC also allows the user to recalibrate control at any time, better accommodating day-to-day variations in socket fit and positioning of the electrodes over the targeted muscle sites. While both systems have been commercially available for more than a decade or more, there is lack of comparative evidence to inform clinical decisions and guide policy. The current trial will investigate potential functional advantages and disadvantages of PRC compared to DC.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
32
All participants will receive in-person training with an onsite study prosthetist for the assigned controller strategy. The purpose of the training will be to instruct users on the care of the device formally and to achieve a basic level of functional performance. Training will be individualized according to clinical discretion consistent with clinical practice. Training will consist of up to four sessions to facilitate participants' use of the assigned controller system. The number of sessions will be competency-based (i.e., determined by the ability of each participant to explain or perform specified tasks). A standardized protocol and training checklist have been developed by clinical subject matter experts (i.e., upper limb prosthetists and occupational therapists).
All participants will receive in-person training with an onsite study prosthetist for the assigned controller strategy. The purpose of the training will be to instruct users on the care of the device formally and to achieve a basic level of functional performance. Training will be individualized according to clinical discretion consistent with clinical practice. Training will consist of up to four sessions to facilitate participants' use of the assigned controller system. The number of sessions will be competency-based (i.e., determined by the ability of each participant to explain or perform specified tasks). A standardized protocol and training checklist have been developed by clinical subject matter experts (i.e., upper limb prosthetists and occupational therapists).
After the training sessions, all subjects will use the PRC device in their homes, just in a different order.
After the training sessions, all subjects will use the DC device in their homes, just in a different order
Virginia Commonwealth University
Richmond, Virginia, United States
Clothespin Relocation Test (CRT)
The CRT measures upper limb prosthesis performance. The test requires participants to rotate each clothespin 90° before placing it onto the vertical bar, which necessitates use of more than one joint motion. Faster completion times are indicative of superior prosthesis control and dexterity. This will be completed under single-task and dual-task conditions.
Time frame: 6 months (During the course of the study procedures/participation)
Brief Activity Measure for Upper Limb Amputees (BAM-ULA)
The BAM-ULA measures an upper limb prosthesis user's ability to perform daily functional activities, including both unimanual and bimanual tasks. This outcome measure requires the participant to tuck their shirt into the back of their pants, place a 20-pound bag on a shelf, open a sealed water bottle and drink from it, remove a wallet from their back pocket, put wallet into their back pocket, take a gallon jug out of the refrigerator, open and pour with the jug, brush their hair, use a fork, and open a door with a doorknob. This outcome measure is scored based on task completion. A higher composite score is indicative of superior prosthesis control.
Time frame: 6 months (During the course of the study procedures/participation)
Jebsen-Taylor Hand Function Test (JTHF)
The JTHF is a standardized measure that tests an individual's unimanual hand function for completing activities of daily living. This test requires the participant to write, turn cards over, pick up and manipulate small objects, simulate feeding, stack checkers, and pick up lighter and heavier larger objects. Faster completion times are indicative of superior prosthesis control and hand function.
Time frame: 6 months (During the course of the study procedures/participation)
Orthotic and Prosthetic Users Survey (UEFS-P)
The UEFS-P measures functional status, quality of life, and satisfaction with devices and services among those receiving orthotic and prosthetic care. Participants will respond to 29 items. Higher scores reflect greater perceived function.
Time frame: 6 months (During the course of the study procedures/participation)
Patient Experience Measure (PEM)
The PEM measures social interaction, self-efficacy, embodiment, intuitiveness, wellbeing, and self-consciousness of upper limb prosthesis users. Higher scores reflect increased ability.
Time frame: 6 months (During the course of the study procedures/participation)
Prosthesis Task Load Index (PROS-TLX)
The PROS-TLX assesses the mental, physical, and emotional demands of using a prosthesis. The PROS-TLX is designed to rate the demand after a specified task is immediately finished. Participants will complete the measure after finishing the performance tests. Higher ratings are indicative of lower mental, physical, or emotional demands.
Time frame: 6 months (During the course of the study procedures/participation)
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