title: Metrics of nasal tip rotation: a comparative analysis.
abstract: OBJECTIVE
  We introduce a new metric for measuring nasal tip rotation, the "columellar facial angle." The present study aimed to determine the degree of correlation of the nasolabial angle, the nostril axis, and the columellar-facial angle as metrics of nasal tip rotation in healthy volunteers. The study also aimed to identify any nasal or facial features unrelated to tip position, which consistently altered these values.
  
  
  METHODS
  Lateral photographs in the Frankfort horizontal plane were taken of 100 volunteers. Measurements of tip rotation were then calculated for each model using three different methods: nasolabial angle, nostril axis, and columellar-facial angle. Data were analyzed for degree of correlation of the three values for all models. Facial features in those subjects with low correlation between measurement methods were analyzed.
  
  
  RESULTS
  For all grouped data, both the nasolabial angle and the nostril axis showed moderate correlations with columellar facial angle but no correlation with each other. Individual subjects whose measurements did not correlate tended to display certain anatomic features: premaxillary deficiency, premaxillary excess, sloped upper lips, or vertical malposition of the nostrils.
  
  
  CONCLUSIONS
  No one method of measurement of nasal tip rotation is reliable for all patients. Certain nasal and facial features are likely to alter these values. Of the three measurement methods presented, the columellar-facial angle is most likely to yield consistent measurements of nasal tip rotation.
authors.affiliation: Department of Otolaryngology, University of California San Francisco, San Francisco, California 94115, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Kim
authors.forename: Kristin K
authors.initials: KK
authors.lastname: Egan
mesh_terms: D005145:Face / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008046:Lip / Q000033:anatomy & histology; D008297:Male; D009666:Nose / Q000033:anatomy & histology*; D010781:Photography; D012399:Rotation; D014894:Weights and Measures