Individual finger strength: are the ulnar digits "powerful"?

This study determined the test-retest reliability of a grip device that measures the contribution of individual fingers to grip strength and described the pattern of contribution in subjects without hand pathology. Subjects repeated a set of three maximal grip efforts on two occasions separated by two to seven days. Intraclass correlation reliability coefficients were high (>0.75) for eight out of ten strength measures. The percentage contributions of the index, middle, ring, and small fingers to grip were approximately 25%, 35%, 25%, and 14%, respectively. Grip and finger strengths were highly correlated. Anthropometric measures of body size or finger length were moderately correlated with strength measures. These data suggest that there is a predictable pattern by which individual fingers contribute to overall grip strength, which is partially related to body size. The ulnar side of the hand contributes to the smaller proportion of overall grip (approximately 60% radial, 40% ulnar). The clinical utility of finger strength measures should be explored.