Capacity Assessment of Prosthetic Performance for the Upper Limb (CAPPFUL): Characterization of Normative Kinematics and Performance.

BACKGROUND: Evaluation of maladaptive compensatory movement is important to objectively identify the impact of prosthetic rehabilitative intervention on body mechanics. The Capacity Assessment of Prosthetic Performance for the Upper Limb (CAPPFUL) scores this type of compensation by comparing movements of the prosthesis user to movements of individuals with intact, sound upper limbs (ULs). However, expected movements of individuals with sound, intact ULs have not been studied for the set of tasks performed in the CAPPFUL. OBJECTIVE: To enhance the scoring approach for the maladaptive compensatory movement domain of the CAPPFUL by defining normative kinematic movement and characterizing variability and repeatability. DESIGN: Clinical measurement. SETTING: Laboratories at the U.S. Food and Drug Administration (FDA) and University of Texas-Arlington. PARTICIPANTS: Convenience sample of 20 participants with no upper limb (UL) disability or impairment. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASUREMENTS: Kinematic trajectories, range of motion, maximum angle, and completion time were calculated. Repeatability and intersubject variability were assessed by calculating Pearson's correlation coefficient (R), adjusted coefficient of multiple correlation (CMCadj), and max SD (SDmax) for nine joint angles at the elbow, shoulder, neck, and torso. RESULTS: For most joints evaluated, repeatability was lower (R < 0.8) for CAPPFUL 3-Zip vest, CAPPFUL 7-Cut w/ knife, and CAPPFUL 8-Squeeze water, implying inconsistent approaches within a subject from trial to trial for a given task. For most tasks, the joint angle SDmax across all participants was <20°. The approach for completing CAPPFUL 1 - Weights in crate and CAPPFUL 4 - Pick up dice was generally similar across participants (CMCadj >0.4). For other tasks, however, different approaches across participants at the torso and shoulder joint can be seen. CONCLUSION(S): This work established the expected movements of individuals with sound, intact ULs for tasks performed in the CAPPFUL that can be used to inform consistent, standardized scoring of the maladaptive compensatory movement domain.

Outcomes and Perception of a Conventional and Alternative Myoelectric Control Strategy: A Study of Experienced and New Multiarticulating Hand Users.

Introduction: The development of multiarticulating hands holds the potential to restore lost function for upper-limb amputees. However, access to the full potential of commercialized devices is limited due to conventional control strategies for switching prosthesis modes, such as hand grips. For example, to switch grips in one conventional strategy, the prosthesis user must generate electromyogram (EMG) triggers (such as a cocontraction), which are cumbersome and nonintuitive. For this reason, alternative control strategies have emerged, which seek to facilitate grip switching. One specific application uses radio frequency identification (RFID) tags programmed with grip information. These tags can be placed on objects in the environment or carried on person. Upon approaching an RFID tag, the user's prosthesis reads the grip programmed on the tag and commands the hand into that grip. The purpose of this study was to compare the conventional strategy (using EMG triggers) with the alternative strategy (using RFID tags). Methods: The study evaluated three subjects: two users who actively use multiarticulating hands ("experienced" users) and one user who had never worn a multiarticulating hand ("new" user). Subjects were evaluated on two performance metrics: trigger completion time and the percentage of triggers that were successful on first attempt (first attempt success rate). Subjects also rated the difficulty, effort, and frustration with each strategy. Results: Results suggested faster trigger completion times with the EMG strategy for the experienced users and mixed results for the new user. Overall, the three subjects rated the RFID strategy as less difficult, tiring, and frustrating than the EMG strategy. Discussion and Conclusions: Continued studies with a larger subject pool are necessary to determine factors influencing performance and patient preference. This would allow identification of best strategies to access the full potential of new commercial devices. Still, the authors suggest that the synergistic use of both strategies can yield great benefits for both experienced and new multiarticulating hand users.