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Reachable Workspace (RWS) Provides an Objective and Psychological State-Independent Measure of Upper Extremity Function
Saman Andalib, BS
1; Maya Hatch, PhD
1; Christopher Lee, BS
1; Luigi Porciuncula Gonzales, BS
2; Amanda Tedesco, BS
1; Tyler R Johnston, MD
2; David Wright, MD
3; Oswald Steward, PhD
2; Ranjan Gupta, MD
41University of California, Irvine, School of Medicine, Irvine, CA; 2University of California, Irvine, Irvine, CA; 3University of California, Irvine, Department of Orthopaedic Surgery, Orange, CA; 4University of California Irvine, Orange, CA
Introduction: There is a lack of broadly accepted objective functional outcome measurement tools of the upper extremity. Reachable Workspace (RWS) offers an objective, user-independent measure of upper extremity function, previously applied in neurology and neuromuscular research. This study evaluates RWS in assessing upper extremity function in healthy young adults in an orthopedic context and investigates the impact of psychological state on outcomes.
Materials and Methods: With IRB approval, we evaluated 53 healthy subjects (20 men, 33 women) aged 18-29 years using a a Microsoft Kinect 2.0™ camera. Data were acquired via a video-guided protocol involving 10 active range of motion tasks. The Relative Surface Area (RSA) was calculated and visually represented for 4 frontal (Q1 to Q4) and 1 posterior quadrant (Q5). RWS was performed twice for reliability assessment. Descriptive statistics and Intraclass Coefficients (ICC) were calculated. Welch's T-test evaluated RSA differences between sexes. Psychological profiles were collected using Generalized Anxiety Disorder-7 (GAD-7) and Patient Health Questionnaire-9 (PHQ-9) surveys. Spearman's rho correlation coefficients assessed correlations between GAD-7/PHQ-9 scores and RSA values.
Results: RWS took an average of 5 minutes per subject. The ICC was 0.90 (95% CI 0.83-0.94) for total RSA of the left arm and 0.84 (95% CI 0.72-0.90) for the right arm. No significant differences were found in RWS scores between sexes for total RSA in healthy controls (right arm P=0.39, left arm P=0.92). No significant correlations were observed between total RSA and GAD-7 scores (left arm r=-0.03, P=0.88; right arm r=-0.07, P=0.71) or PHQ-9 scores (left arm r=-0.06, P=0.77; right arm r=-0.16, P=0.42). Subgroup analyses comparing subjects with minor (GAD-7/PHQ-9 scores 0-4) and significant symptoms (scores >4) showed no significant differences in mean RSA values (GAD-7: P=0.57; PHQ-9: P=0.71).
Conclusions: RWS is a practical, reliable tool for assessing upper extremity function in an orthopedic clinic. This study provides a valuable characterization of RSA for bilateral upper extremities in healthy young adults, across sex and psychological profiles. No significant differences were found between sexes, nor was there a relationship with psychological state. This study validates the feasibility and reliability of RWS in an orthopedic setting, showing it to be readily deployable and valuable in clinical practice.
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