Objective assessment of tip projection and the nasolabial angle in rhinoplasty.

摘要

OBJECTIVE: To provide an objective method to measure the extent of nasal tip projection and the nasolabial angle. DESIGN: We retrospectively studied preoperative and postoperative images using a novel approach. The constant position of the cornea in lateral views and the diameter of the iris in frontal views were used to standardize and compare digitalized images of patients before and after surgery. We tested this objective assessment technique using the digitized slides of patients with saddle nose deformities and measured changes in their nasal tip projection and nasolabial angle. We included 63 patients who had undergone an open rhinoplasty with the I-beam technique by the same surgeon over a 7-year period. We tested the reproducibility of these measurements with 10 independent investigators. We also determined whether the measurements using this objective technique correlated with the surgeon's or patients' subjective assessments of the outcome. RESULTS: We were able to use the objective measurement technique in 42 patients (67%). It was not possible to use the technique in 21 patients (33%) because the photographic conditions had not been fulfilled. The measurement variability of 10 different investigators expressed as standard deviations in percentage of the mean value was 6.7% for nasal tip projection and 1.3% for the nasolabial angle. The surgeon's subjective assessment of the outcome correlated with the objective changes of nasal tip projection (P =.045) and the nasolabial angle (P =.045). There was no correlation between the patients' assessments and the objective measurements. CONCLUSIONS: The objective measurements tested were easy to use and investigator independent. They also correlated with the surgeon's assessment of outcome.