Quantifying nuanced differences in hand dexterity between the dominant and nondominant hands of healthy,...

When individuals present with hand injuries, clinicians often use the contralateral hand as an internal control. However, subtle differences in baseline dexterous abilities between the dominant and nondominant hands are poorly understood. To address this gap, here we quantified such differences, measured as independence (individuation) and smoothness of finger movements. A cohort of 47 right-hand-dominant healthy adults (22 males and 25 females) moved each finger independently 10 times, while joint angle data were tracked with a dataglove (CyberGlove III, CyberGlove Systems, San Jose, CA). Each finger's performance was compared with its counterpart on the opposite hand using Wilcoxon-signed rank tests. The right hand scored significantly higher than the left on both direct comparison and linear mixed-effect modeling for thumb individuation (P < 0.0001) and smoothness (P < 0.0001), index finger individuation (P = 0.012), and middle finger individuation (P = 0.009). Differences between the hands for index and middle finger individuation scores changed depending on the individuation scoring method used. Sex-based comparisons revealed females had greater asymmetry of thumb (P = 0.044) and ring finger (P = 0.020) individuation scores, as well as ring finger smoothness (P = 0.036) compared with males on both direct comparison and multiple linear regression. Cluster and principal components analysis were performed to detect whole hand differences. Dominant and nondominant hands were separated using smoothness metrics at a 74.5% sensitivity, 66% specificity, 68.6% positive predictive value, and 72.1% negative predictive value. In sum, this represents the largest study to date quantifying naturally occurring differences in hand dexterity between dominant and nondominant hands in healthy, right-handed young adults.NEW & NOTEWORTHY Here we present the largest study to date quantifying differences in finger dexterity between the dominant and nondominant hands in healthy, right-hand-dominant, young adults using finger individuation and smoothness. To our knowledge, we are the first to demonstrate differences between dominant and nondominant thumb, index, and middle finger dexterity metrics. Whole hand analyses indicate the dominant and nondominant hands can be separated based on smoothness with above-chance sensitivity and specificity.