Hitomi Sano1, Kaori Shionoya, Rei Ogawa. 1. Department of Surgical Science, Graduate School of Medicine, University of Tokyo, Tokyo, Japan; Department of Plastic, Reconstructive and Aesthetic Surgery, Nippon Medical School, Tokyo, Japan.
Abstract
BACKGROUND: We studied the relationship between mechanical force and nail curvature. METHODS: The effect of different frequencies and strengths of mechanical force on nail curvature was assessed. In Study 1, 63 carpenters and 63 office workers were enrolled, and the configurations of their thumb nails were assessed by measuring the curve index (defined as nail height/width) and pinch strength. In Study 2, nail curvature and pinch strength of jazz bassists, who characteristically do not use the right fourth and fifth fingers but use the left fifth finger a lot, were compared. In Study 3, the thumb nail curvature and pinch strength of the dominant and nondominant sides of the 126 participants from Study 1 were compared. RESULTS: Study 1: Carpenters had a significantly lower mean thumb nail curve index and higher mean pinch strength. Study 2: The nails of the unused right fourth and fifth fingers were much more curved than the nails of the frequently used left fourth and fifth fingers. The pinch strength of the right fifth finger was much weaker than the pinch strength of the left fifth finger. Study 3: The dominant side had a significantly lower nail curve index and higher pinch strength. CONCLUSION: The frequency and strength of mechanical forces on finger nails significantly affect nail appearance.
BACKGROUND: We studied the relationship between mechanical force and nail curvature. METHODS: The effect of different frequencies and strengths of mechanical force on nail curvature was assessed. In Study 1, 63 carpenters and 63 office workers were enrolled, and the configurations of their thumb nails were assessed by measuring the curve index (defined as nail height/width) and pinch strength. In Study 2, nail curvature and pinch strength of jazz bassists, who characteristically do not use the right fourth and fifth fingers but use the left fifth finger a lot, were compared. In Study 3, the thumb nail curvature and pinch strength of the dominant and nondominant sides of the 126 participants from Study 1 were compared. RESULTS: Study 1: Carpenters had a significantly lower mean thumb nail curve index and higher mean pinch strength. Study 2: The nails of the unused right fourth and fifth fingers were much more curved than the nails of the frequently used left fourth and fifth fingers. The pinch strength of the right fifth finger was much weaker than the pinch strength of the left fifth finger. Study 3: The dominant side had a significantly lower nail curve index and higher pinch strength. CONCLUSION: The frequency and strength of mechanical forces on finger nails significantly affect nail appearance.