title: Influence of mechanical forces as a part of nail configuration.
abstract: BACKGROUND
  Clinicians encounter pincer nails at a high incidence among bedridden cases who are free from weight bearing. The mechanical force transmitted by walking and loading may affect the nail configuration. This study was aimed at evaluating the influence of mechanical forces on the nail configuration.
  
  
  METHODS
  Study 1 was conducted on a sample size of 318 great toenails, with the subjects classified into the following 3 groups: healthy volunteers, participants who were bedridden for less than 3 months, and participants who were bedridden for more than 3 months. Study 2 was conducted in 12 subjects with unilateral loading.
  
  
  METHODS
  The configuration of the great toenails, in terms of the curve index (defined as the nail height/nail width), was compared.
  
  
  RESULTS
  In study 1, the curve index increased significantly as the duration of the bedridden state became longer (17.5 ± 4.75, 28.9 ± 11.0, 36.4 ± 9.58, respectively). In study 2, the curve index on the nonloaded side was significantly higher than that on the loaded side (40.0 ± 8.63 vs. 27.0 ± 8.39).
  
  
  CONCLUSIONS
  Our results suggest that mechanical forces may affect the nail configuration and be involved in the pathophysiology of nail deformities.
authors.affiliation: Department of Surgical Science, Graduate School of Medicine, University of Tokyo, Tokyo, Japan. sasasa116sasasa@hotmail.com
authors.forename: Hitomi
authors.initials: H
authors.lastname: Sano
authors.forename: Shigeru
authors.initials: S
authors.lastname: Ichioka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009260:Nail Diseases / Q000503:physiopathology*; D009262:Nails / Q000254:growth & development*; D009264:Nails, Malformed / Q000503:physiopathology*; D014034:Toes; D016474:Weight-Bearing / Q000502:physiology