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Front. Neurol. | doi: 10.3389/fneur.2019.00857

A taxonomy of functional upper extremity motion

  • 1Department of Neurology, School of Medicine, New York University, United States
  • 2Department of Medicine, School of Medicine, New York University, United States
  • 3Department of Neurology, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, United States
  • 4Department of Rehabilitation Medicine, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, United States

Background: Functional upper extremity (UE) motion enables humans to execute activities of daily living (ADLs). There currently exists no universal language to systematically characterize this type of motion or its fundamental building blocks, called primitives. Without a standardized classification approach, pooling mechanistic knowledge and unpacking rehabilitation content will remain challenging.
Methods: We created a taxonomy to characterize functional UE motions occurring during ADLs, classifying them by motion presence, temporal cyclicity, upper body effector, and contact type. We identified five functional primitives by their phenotype and purpose: reach, reposition, transport, stabilize, and idle. The taxonomy was assessed for its validity and interrater reliability in right-paretic chronic stroke patients performing a selection of ADL tasks. We applied the taxonomy to identify the primitive content and motion characteristics of these tasks, and to evaluate the influence of impairment level on these outcomes.
Results: The taxonomy could account for all motions in the sampled activities. Interrater reliability was high for primitive identification (Cohen’s kappa = 0.95-0.99). Using the taxonomy, the ADL tasks were found to be composed primarily of transport and stabilize primitives mainly executed with discrete, proximal motions. Compared to mildly impaired patients, moderately impaired patients used more repeated reaches and axial-proximal UE motion to execute the tasks.
Conclusions: The proposed taxonomy yields objective, quantitative data on human functional UE motion. This new method could facilitate the decomposition and quantification of UE rehabilitation, the characterization of functional abnormality after stroke, and the mechanistic examination of shared behavior in motor studies.

Keywords: primitive, Rehabilitation, Dose, Upper Extremity, function, Stroke

Received: 10 Apr 2019; Accepted: 24 Jul 2019.

Edited by:

Thomas Platz, University of Greifswald, Germany

Reviewed by:

George Wittenberg, University of Maryland SoM
Joachim Hermsdörfer, Technical University of Munich, Germany  

Copyright: © 2019 Schambra, Parnandi, Pandit, Uddin, Wirtanen and Nilsen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Heidi M. Schambra, Department of Neurology, School of Medicine, New York University, New York, 10017, New York, United States,