To Evaluate the Clinical Impact of the Point Powered System

Assessment of Capacity for Myoelectric Control (ACMC)

The proctor for the measure chooses an everyday activity, such as setting up a table for snacks or replanting a flower, that is relevant to the study population. As the participants perform the chosen task, a trained rater will assess their capacity for control of their myoelectric prosthesis as represented by 30 items reflecting 6 aspects of quality of myoelectric control. These 6 aspects are "the need for external support," "grip force and opening width," "coordination of both hands, "in different positions and in motion (timing)," "repetitive grip and release," and "the need for visual feedback." Each item is scored on a 4-point scale and converted into linear measures of myoelectric control using Rasch analysis methods on the ACMC website. ACMC is the only measure that has been validated for individuals with upper limb (UL) loss who use myoelectric control and has been shown to demonstrate good test-retest reliability.

The Southampton Hand Assessment Procedure (SHAP)

The SHAP is a time based test of a standardized protocol of 26 timed activities of daily living (ADL) tasks. The SHAP has a set of "common objects" representative of everyday items for the user to pick up. The results of the SHAP is a score which directly compares the abilities of the subject with those of intact able-bodied individuals as well as more refined scores for six prehensile patterns. A SHAP score of 100 is what an intact person is expected to achieve. This test has been validated for normative data.

PROMIS Social Isolation

PROMIS Social Isolation is a self-reported person-centered measure that focuses on perceptions of being avoided, excluded, detached, disconnected from, or unknown by, others. Responses are scored on a scale of 1 to 5. Individual response scores are summed to get a raw score, which can be converted to a standardized T-score with a mean of 50 and standard deviation of 10.

PROMIS Ability to Participate

PROMIS Ability to Participate is a self-reported person-centered measure that focuses on perceived ability to perform one's usual social roles and activities. Responses are scored on a scale of 1 to 5. Individual response scores are summed to get a raw score, which can be converted to a standardized T-score with a mean of 50 and standard deviation of 10.

Mean Prosthesis Wear Duration (MPWD)

We will measure the mean duration of daily prosthesis wear as a proxy for improved prosthesis acceptance. Prosthesis wear time is defined as the time from when participants don their prostheses to the time they doff their prostheses. The time points are both recorded by participants and through analysis of the activity monitors. We believe the mean prosthesis wear duration is an important metric as it is possible that participants who have higher levels of satisfaction with their prosthesis will wear their prosthesis for long periods of time. It is also possible that wear time may not necessarily be correlated with corresponding usage of the prosthetic limb. Measuring this variable will be important in its assessment in comparison with other variables.

Bilateral magnitude (BM)

Participants will be asked to wear accelerometers on each wrist throughout the study. From accelerometry data, we will calculate the bilateral magnitude (BM), which quantifies the intensity of activity across both arms for a given duration. A BM of 0 indicates that no activity occurs and increasing BMs indicate that more bilateral activity occurs.

Magnitude ratio (MR)

Participants will be asked to wear accelerometers on each wrist throughout the study. From accelerometry data, we will calculate magnitude ratio (MR), which is the ratio of acceleration between the two arms for a given duration. A MR of 0 indicates equivalent contribution of activity from both arms; positive values of MR indicate that more prosthesis-side activity occurs and negative values of MR indicate that more sound-side activity occurs.

Secondary activity duration variables

In addition to BM and MR, we will also calculate durations of non-injured UL activity, amputated UL activity, simultaneous UL activity, and total UL activity averaged across each day. Measurements of activity durations by UL side can provide additional insight into how much one side is used over another and with respect to bilateral use. This measure is complimentary to BM and MR measures and will help us determine if the Point Powered promotes more use of the prosthesis side relative to the standard-of-care.