title: Morphologic study of normal, ingrown, and pincer nails.
abstract: BACKGROUND
  Pincer nail has been confused with ingrown nail for decades.
  
  
  OBJECTIVE
  The objectives were to analyze the circumferential length of pincer nail and the relationship between nail deformity and the underlying distal phalangeal shape.
  
  
  METHODS
  The circumferential length of 53 pincer nails was determined at successive 5-mm intervals of the nail plate. Sixty great toes, including normal (n=20), ingrown (n=20), and pincer nails (n=20), were assessed with respect to body height, body weight, body mass index, nail height, nail width index, and nail height index. Nail angle and height of osteophyte were measured.
  
  
  RESULTS
  Despite the presence or absence of overcurvature, the circumferential length displayed nearly identical values across the proximal to distal range of the nail. In the pincer nail group, only the correlation between the width and height indices was statistically significant; 50%, 80%, and 100% of cases were confirmed based on osteophyte presence in normal, ingrown, and pincer nails.
  
  
  CONCLUSIONS
  The findings suggest that the mechanical cause may be associated with the over curved nail, which is affected by nail bed contraction. Results may support the hypothesis that an osteophyte of the distal phalanx may not be a cause of, but rather a result of, an overcurving deformity.
authors.affiliation: Department of Plastic and Reconstructive Surgery, Kinki University School of Medicine, Osakasayama City, Osaka, Japan. kosaka@kouhoukai.or.jp
authors.forename: Masaaki
authors.initials: M
authors.lastname: Kosaka
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Kusuhara
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Mochizuki
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Mori
authors.forename: Noritaka
authors.initials: N
authors.lastname: Isogai
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009260:Nail Diseases / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D009262:Nails / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D011859:Radiography; D055815:Young Adult