Objective Assessment of Tip Projection and the Nasolabial Angle in Rhinoplasty Susanne Spörri; Daniel Simmen, MD; Hans Rudolf Briner, MD; Nick Jones, MD, FRCS 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 con- stant position of the cornea in lateral views and the di- ameter of the iris in frontal views were used to standard- ize and compare digitalized images of patients before and after surgery. We tested this objective assessment tech- nique using the digitized slides of patients with saddle nose deformities and measured changes in their nasal tip projection and nasolabial angle. We included 63 pa- tients who had undergone an open rhinoplasty with the I-beam technique by the same surgeon over a 7-year pe- riod. We tested the reproducibility of these measure- ments with 10 independent investigators. We also de- termined whether the measurements using this objective technique correlated with the surgeon’s or patients’ sub- jective assessments of the outcome. Results: We were able to use the objective measure- ment technique in 42 patients (67%). It was not pos- sible 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 assess- ment of the outcome correlated with the objective changes of nasal tip projection (P = .045) and the naso- labial 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 cor- related with the surgeon’s assessment of outcome. Arch Facial Plast Surg. 2004;6:295-298 A CCURATE PREOPERATIVE and postoperative analy- sis and evaluation of the anatomy and appearance of the nose are essential for assessing the efficacy of surgical tech- niques, as well as for modifying surgical procedures based on their long-term out- come.1-9 Photographs,3,4 cephalometric radiographs,1 and direct clinical mea- surements5,6 are the primary means by which the nasal tip has been assessed, but few studies have addressed quantita- tive changes in nasal tip projection7,8 and the nasolabial angle. A universally ac- cepted method of assessing nasal tip pro- jection and the nasolabial angle has not been described, to our knowledge. The measuring techniques described to date are laborious and often dependent on the patient’s compliance, and they do not make use of modern computer technol- ogy, eg, measurements from life-size pro- jections of slides,8,9 or tools such as the na- sal projectometer.5,9 Our aim was to establish an objec- tive, practical, easy-to-use, computer- assisted rhinoplasty assessment tech- nique for measuring the extent of nasal tip projection and the nasolabial angle based on an iris-dependent calibration of exist- ing profile photographs (if they fulfill mini- mal photographic conditions). METHODS The photographs of 63 patients with saddle nose deformities were used to study the rhi- noplasty assessment technique. All patients had changes in the degree of nasal tip pro- jection and the nasolabial angle after an open rhinoplasty with an I-beam transplan- tation performed by the same surgeon over a 7-year period. I-beam transplantation is a surgical technique that is used to increase nasal tip support and projection. There were 31 men (49%) and 32 women (51%), with a mean ± SD age of 40.1 ± 13.5 years (age range, 15-64 years). All patients were white. Follow-up ranged from 1 to 24 months. During the follow-up period, photographs of See also page 299 ORIGINAL ARTICLE From the Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital (Ms Spörri), and the Center for Otology, Skull Base Surgery, Rhinology, and Facial Plastic Surgery, Klinik Hirslanden (Drs Simmen and Briner), Zurich, Switzerland; and the Department of Otorhinolaryngology, University of Nottingham, Nottingham, England (Dr Jones). (REPRINTED) ARCH FACIAL PLAST SURG/ VOL 6, SEP/OCT 2004 WWW.ARCHFACIAL.COM 295 ©2004 American Medical Association. All rights reserved. the right and left profiles and a frontal view were taken 1 to 4 times. The measurements were performed on retrospectively digi- tized preoperative and postoperative right profile slides of nonsmiling patients. We used commercially available software (ImageAccess; PIC Systems AG, Glattbrugg, Switzerland). On preoperative and postoperative digitized slides, the degree of nasal tip projection and the nasolabial angle were analyzed ob- jectively using 4 defined lines superimposed on the face (Figure 1 and Figure 2). One line, which was drawn from the superior aspect of the tragus through the lateral canthus (Figure 1, point A), extending over the nasal root, was used to define the nasal frontal angle (Figure 1, point B), which is of- ten difficult to locate in a reproducible fashion. The measure- ment of the distance from A to B was used to define changes in the nasal frontal angle between the preoperative and postop- erative photographs. A second line was drawn from the nasal frontal angle (Figure 1, point B) to the vermillion cutaneous junction of the upper lip (Figure 1, point C). A third line, per- pendicular to the second, meets the most projecting part of the nasal tip (Figure 1, point E). The length of this third line (Fig- ure 1, D-E) in millimeters was used as a determinant of nasal tip projection. The angle between the second line (Figure 1, B-C) and the fourth line (Figure 1, F-G), following the colu- mella, was used to measure the nasolabial angle. The calibra- tion was performed using the mean ± SD diameter of the iris and cornea, which is consistently 11.5 ± 0.6 mm in adults. After cali- bration, the values were recalculated to life-size. The photographic conditions require a full-profile pho- tograph, with no rotation of a nonsmiling patient’s head. The patient’s eyes should be wide open, with a straight gaze, for ex- act calibration, and the superior aspect of the tragus, the lat- eral canthus, and the vermillion-cutaneous junction of the up- per lip should be visible. To evaluate investigator-dependent variability, 10 ran- domly chosen adult individuals were instructed regarding the aforementioned criteria and taught how to use the computer software to magnify or reduce the images, allowing them to stan- dardize the images before they did the measurements. Ques- tions were answered on demand. To compare objective measurements with subjective as- sessment, the patients and the surgeon were asked whether the outcome of the operation was successful. The 2 groups were classified as successful or unsuccessful, and each of the pa- tient’s and the surgeon’s results were compared using the Mann- Whitney rank-sum test. Statistical significance was defined by P�.05. RESULTS Changes in nasal tip projection and the nasolabial angle could be quantified in 42 patients (67%). Figure 2 shows a representative example of these measurements with pre- operative and postoperative measurements. An increase in nasal tip projection and nasolabial angle was noted in 31 (74%) and 33 (79%) patients, respectively, while a de- crease occurred in 11 (26%) and 9 (21%) patients. We were unable to use the rhinoplasty assessment technique in 21 patients (33%). The pictures of 12 pa- tients (19%) failed to show the ears; therefore, the nec- essary landmarks were lacking. Calibration was not pos- sible in 1 case because the patient’s closed eyes were closed and therefore his irises were hidden. The preoperative pictures of 5 patients (8%) and the preoperative and postoperative pictures of 2 patients (3%) were missing. In the preoperative picture of 1 patient, the profile was rotated. The measurement variability of 10 different inves- tigators is summarized in the Table. According to the surgeon’s assessment, the measurements in the group in which surgery was successful (n = 34) differed signifi- cantly from those in the group in which surgery was un- successful (n = 8) (P = .045 for both nasal tip projection and nasolabial angle). There were no significant differ- ences regarding nasal tip projection (P = .18) or nasola- bial angle (P = .08) between the 2 groups (38 successful outcomes vs 4 unsuccessful outcomes) when the mea- surements were assessed by the patients. COMMENT We have developed and tested an objective computer- assisted technique to assess nasal tip projection and the nasolabial angle with the use of an iris-dependent cali- bration, which is possible because the diameter of the iris in adults is 11.5 ± 0.6 mm, showing an extraordinary con- stancy, and any divergence from these measurements is pathological.10 With the use of this technique, differ- A B D E G F C Figure 1. Lateral view. Rhinoplasty assessment technique and photographic conditions illustrated by 4 lines superimposed on the face. A indicates the lateral canthus; B, the nasal frontal angle defined by a line from the superior aspect of the tragus through point A extended on to the nasal root; C, the vermillion cutaneous junction of the upper lip; D-E, the line that is perpendicular to B-C, extending to the most projecting part of the nasal tip; and F-G, the line that follows the columella. The length of D to E is used as a determinant for nasal tip projection. The angle between lines B to C and F to G determines the nasolabial angle. (REPRINTED) ARCH FACIAL PLAST SURG/ VOL 6, SEP/OCT 2004 WWW.ARCHFACIAL.COM 296 ©2004 American Medical Association. All rights reserved. ences in photograph size do not affect the measure- ments, as every distance is standardized. The technique is easy to use and can be applied to most existing pho- tographs that fulfill limited photographic criteria. Using computer technology is preferable to using manual mea- surements with callipers and rulers (eg, nasal tip projec- tometer5) or measurements taken from the life-size pro- jection of slides7 because the results are more reproducible. Given the current excellent image quality and ongoing refinements in digital photography, converting to digi- tal photography is fast and cost-effective,11 especially when the cost of digital photography is compared with the cost of serial cephalometric studies. Furthermore, cephalo- metric studies are laborious and are associated with ra- diation exposure.1 Instead of nasal tip projection being expressed as a ratio of midface length,4,12,13 the technique described herein expresses measurements in absolute values based on iris- dependent calibration, which allows a more accurate com- parison for future studies. We analyzed interinvestigator variability, and al- though the different investigators were only briefly in- troduced to the technique, the interinvestigator variabil- ity was less than 10%. We conclude that this method is easy to learn and provides reproducible results. The ob- jective values correlate with the subjective assessment of the experienced surgeon; therefore, the technique can also be used to rate the success of rhinoplasty. To our knowl- edge, this correlation has not been demonstrated with any Interinvestigator Variability of the Rhinoplasty Assessment Technique Investigator No.* Age, y† Profession Nasal Tip Projection, mm‡ Nasolabial Angle, Degrees§ 1 41 Physician 18.40 99.91 2 39 Photographer 19.06 99.29 3 25 Secretary 18.28 98.73 4 23 Secretary 17.12 97.26 5 39 Secretary 16.80 99.17 6 36 Nurse 17.95 101.40 7 28 Nurse 20.07 101.20 8 26 Nurse assistant 19.58 100.20 9 42 Nurse 20.47 100.45 10 33 Physician 17.55 101.18 *All 10 investigators were female. †Mean, 26. ‡Mean ± SD, 18.53 ± 1.24; SD%, 6.7. §Mean ± SD, 99.88 ± 1.30, SD%, 1.3. NTP = 9.3 mm NTP = 12.3 mm NLA = 105.8° NLA = 97.6° Figure 2. A, The right profile of a patient before rhinoplasty, with 4 lines and the resulting values of the preoperative nasal tip projection (NTP) (9.3 mm) and the nasolabial angle (NLA) (105.8°) superimposed. B, The same patient after rhinoplasty, with changes in the NTP (12.3 mm) and the NLA (97.6°). The computer-assisted calibration defines the radius of the iris as 5.75 mm in each picture, ensuring standardization of the patients’ photographs. (REPRINTED) ARCH FACIAL PLAST SURG/ VOL 6, SEP/OCT 2004 WWW.ARCHFACIAL.COM 297 ©2004 American Medical Association. All rights reserved. other measuring technique. The surgeon’s assessment did not correlate with the patients’ assessment probably because of the small number of patients involved and because patients are usually satisfied more easily than surgeons.2 Accepted for publication December 11, 2003. This study was presented in part at “The Nose 2000 . . . and Beyond”; September 20-23, 2000; Washing- ton, DC; and at the 89th Spring Meeting of the Swiss Soci- ety of Otorhinolaryngology; June 20-22, 2002; Pontresina, Switzerland. Correspondence: Daniel Simmen, MD, ORL-Zentrum, Klinik Hirslanden, Witellikerstrasse 40, CH-8029 Zurich, Swit- zerland (simmen@orl-zentrum.com). REFERENCES 1. Werther JR, Freeman JP. 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Kohout MP, Monasterio Aljaro L, Farkas LG, Mulliken JB. Photogrammetric com- parison of two methods for synchronous repair of bilateral cleft lip and nasal deformity. Plast Reconstr Surg. 1998;102:1339-1349. 9. Webster RC, Davidson TM, Rubin FF, Smith RC. Recording projection of nasal landmarks in rhinoplasty. Laryngoscope. 1977;87:1207-1211. 10. Rauber A, Kopsch F. Anatomie des Menschen, Band III, Nervensystem, Sinne- sorgane. Stuttgart, Germany: Georg Thieme Verlag; 1987:533-538. 11. Hollenbeak CS, Kokoska M, Stack BC. Cost considerations of converting to digi- tal photography. Arch Facial Plast Surg. 2000;2:122-123. 12. Crumley RL, Lanser M. Quantitative analysis of nasal tip projection. Laryngo- scope. 1988;98:202-208. 13. Bafaqeeh SA. Open rhinoplasty: effectiveness of different tipplasty techniques to increase nasal tip projection. Am J Otolaryngol. 2000;21:231-237. (REPRINTED) ARCH FACIAL PLAST SURG/ VOL 6, SEP/OCT 2004 WWW.ARCHFACIAL.COM 298 ©2004 American Medical Association. 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