Effectiveness of subspinal Le Fort I osteotomy in preventing postoperative nasal deformation

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Effectiveness of subspinal Le Fort I osteotomy in preventing postoperative nasal deformation Yosuke Yamashsita , Toshinori Iwai , Koji Honda , Koichi Fujita , Haruki Imai , Hikaru Takasu , Susumu Omura , Makoto Hirota , Kenji Mitsudo PII: DOI: Reference:

S1748-6815(20)30073-5 https://doi.org/10.1016/j.bjps.2020.02.014 PRAS 6438

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Journal of Plastic, Reconstructive & Aesthetic Surgery

Received date: Accepted date:

6 July 2019 9 February 2020

Please cite this article as: Yosuke Yamashsita , Toshinori Iwai , Koji Honda , Koichi Fujita , Haruki Imai , Hikaru Takasu , Susumu Omura , Makoto Hirota , Kenji Mitsudo , Effectiveness of subspinal Le Fort I osteotomy in preventing postoperative nasal deformation, Journal of Plastic, Reconstructive & Aesthetic Surgery (2020), doi: https://doi.org/10.1016/j.bjps.2020.02.014

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Effectiveness of subspinal Le Fort I osteotomy in preventing postoperative nasal deformation Yosuke Yamashsita a, Toshinori Iwai b,*, Koji Honda b, Koichi Fujita a, Haruki Imai a, Hikaru Takasu a, Susumu Omura a, Makoto Hirota a, Kenji Mitsudo b

a Department of Oral and Maxillofacial Surgery/Orthodontics, Yokohama City University Medical

Center, Yokohama, Kanagawa, Japan.

b Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of

Medicine, Yokohama, Kanagawa, Japan.

* Corresponding author: Toshinori Iwai

e-mail: [email protected]

Summary Purpose: This study sought to determine the effectiveness of subspinal Le Fort I osteotomy (SLFIO)

in preventing nasal deformation, by analyzing changes in nasal profile on three-dimensional

computed tomography (3D-CT) images.

Patients and methods: The participants were 39 Japanese patients with mandibular prognathism (6

men and 33 women) who underwent bilateral sagittal split ramus osteotomy and Le Fort I osteotomy

with maxillary advancement: SLFIO was performed in 20 patients and conventional Le Fort I

osteotomy (CLFIO) in 19 patients. All patients underwent modified alar base cinch suture, V-Y

closure, and reduction of the piriform aperture. CT data acquired before and 1 year after the surgery

were evaluated three-dimensionally with software to determine changes in nasal profile.

Results: Changes in alar width, alar base width, nasal length, and nasofrontal angle were

significantly smaller following SLFIO than following CLFIO, although there were no significant

differences in nasal projection, nasal tip angle, or nasolabial angle between two procedures.

Conclusion: SLFIO for anterior repositioning of the maxilla can prevent undesirable transverse soft

tissue changes of the nose.

Keywords: subspinal Le Fort I osteotomy, nasal deformation, computed tomography, maxillary advancement

Introduction Undesirable nasolabial changes following Le Fort I osteotomy for anterior and/or superior

repositioning of the maxilla may include increased alar base width, upturning of the nasal tip,

flattening and thinning of the upper lip, loss of normal lip pout, and downturning of the corners of the mouth.1,2 Many surgical techniques have been applied to control or minimize these changes in Le

Fort I osteotomy, such as alar base cinch sutures, V-Y closure, anterior nasal spine (ANS) reduction, and nasal floor reduction.1,2 Despite some success with these techniques, the outcome is still

unpredictable, especially for anterior and/or superior maxillary repositioning.

To address this, subspinal Le Fort I osteotomy (SLFIO) has been performed to preserve the perinasal musculature insertions and the pre-existing position of the ANS and nasal septum.3,4

However, the effectiveness of this technique remains to be clarified. The purpose of this

retrospective nonrandomized study was to evaluate the effectiveness of SLFIO in preventing nasal

deformation by analyzing changes in nasal profile using three-dimensional computed tomography

(3D-CT) images.

Materials and Methods

Patients Thirty-nine Japanese patients with mandibular prognathism (6 men and 33 women; mean age 23.8

years, age range 16-49 years) underwent bilateral sagittal split ramus osteotomy (BSSO) and Le Fort

I osteotomy with maxillary advancement and clockwise rotation between August 2012 and February

2014 at our hospital. They had no history of congenital facial deformity or midfacial surgery.

Surgical procedure All bimaxillary orthognathic surgeries were performed by one surgeon with same surgical team. All

patients underwent modified alar base cinch suture, V-Y closure, and reduction of the piriform

aperture. SLFIO was performed for 20 patients and conventional Le Fort I osteotomy (CLFIO) was

performed for 19 patients. Subspinal osteotomy to retain the nasolabial muscle origins was performed as V-shaped osteotomy at the base of the ANS via a circumvestibular incision (Fig. 1),3

and a hole for the alar base cinch suture was then drilled in the ANS. A 2/0 nonabsorbable suture was placed using a modification of Rauso et al.’s alar base cinch suture technique5, in which the suture

was passed through both nasalis muscles, fibrous connective tissue, the lesser alar cartilage, and the

hole in the ANS (Fig. 2). The actual nasal width was overcorrected by this procedure as much as

possible.

Image acquisition and analysis CT was performed with a 64-slice CT scanner (Aquilion 64; Toshiba Medical Systems, Tokyo,

Japan) a few weeks before and 1 year after the bimaxillary orthognathic surgery. The imaging

conditions were as follows: 120 kVp, 300 mA, 750 ms exposure time, and 0.5 mm thickness. CT

data were store in Digital Imaging and Communications in Medicine (DICOM) format. The DICOM

images were then entered into imaging software (Dolphin 3D, version 11.7 Premium; Dolphin

Imaging, Chatsworth, CA). Image segmentation was performed based on the Hounsfield units

assigned to each pixel in the DICOM image series. Superimposition was performed using automatic voxel-based registration with subvoxel accuracy by maximization of mutual information,6 with the anterior cranial base used as a stable registration area.7,8 This automatic Dolphin 3D voxel-based

superimposition, which avoids operator error, is reported to be fast, use-friendly, precise, and reliable.8

Assessment Preoperative and postoperative measurements were repeated twice by a single investigator using the

software at 2-week intervals, and the mean values of the measurements were recorded. Maxillary

movements at Point A (Pt A), the posterior nasal spine (PNS), the incision superius (Is) and ANS

following orthognathic surgery with CLFIO or SLFIO were evaluated in the X, Y, and Z coordinate

system (X-axis: transverse axis, Y-axis: sagittal axis and Z-axis: vertical axis). The following

measurement landmarks were used: alare (Al), alar curvature (Ac), soft tissue glabella (Gs), soft

tissue nasion (Ns), pronasale (Prn), columella (Cm), subnasale (Sn), and labrale superior (Ls). The

following distances and angles were evaluated three-dimensionally (Fig. 3):

1.

Nasal width: Al-Al

2.

Alar base width: Ac-Ac

3.

Nasal length: Ns-Prn

4.

Nasal tip projection (perpendicular distance): Ns-Prn

5.

Nasofrontal angle: Gs-Ns-Prn

6.

Nasal tip angle: Ns-Prn-Sn

7.

Nasolabial angle: Cm-Sn-Ls Furthermore, questionnaire (Table 1) was used to assess patients’ satisfaction 1 year after

bimaxillary surgery.

Statistical analysis Wilcoxon’s rank sum test was used to compare maxillary movements following orthognathic surgery

with CLFIO or SLFIO and to compare the preoperative and postoperative measurements between

the two procedures. Differences were considered significant at p < 0.05. Statistical analyses were

performed with JMP 12 (SAS Institute Inc., Cary, NC). Intraclass correlation analyses were

performed to evaluate the reliability of the preoperative and postoperative measurements, using

SPSS 22.0 for Windows (SPSS Inc., Chicago, IL).

Results Movements of Pt A, PNS and Is showed no significant differences between the two procedures

(Table 2). However, sagittal and vertical movements of ANS in SLFIO was significantly less than

their movements in CLFIO (Table 2). There were significantly smaller changes in nasal morphology

with respect to alar width, alar base width, nasal length, and nasofrontal angle following SLFIO than

following CLFIO (Table 3). However, there were no significant differences in nasal projection, nasal

tip angle, or nasolabial angle between the two procedures (table 3). Intraclass correlation analyses

showed the reliability of all preoperative and postoperative measurements (r = 0.897-0.997, p <

0.05).

In questionnaire, all patients answered good for facial aesthetics after surgery. For nasal

aesthetics after CLIFO, good and fair were 3 (15.8%) and 16 (84.2%), respectively. In contrast, for

nasal aesthetics in SLFIO group, good and fair were 8 (40.0%) and 12 (60.0%), respectively.

Discussion Nasal deformation after Le Fort I osteotomy can occur by advancement and/or impaction of the maxilla.3 In particular, nasal base widening can be caused by spatial change of the supportive bone, edema, and release of the periosteum and muscle attachments.9 Schendel and Williamson10 were the

first to suggest that transection without reapproximation of the perioral and perinasal musculature

was the major reason for unesthetic postoperative changes in the nasolabial region, and they

recommended alar base cinch suture and V-Y closure for lip advancement and muscle reorientation.

Many authors have subsequently reported modifications of alar base cinch suture, and

other effective techniques have also been devised to improve nasolabial changes after surgery. For example, Mommaerts et al.3 tried to avoid unfavorable changes by performing SLFIO (but with no

alar base cinch suture or V-Y closure) to preserve the nasolabial muscle origins to the ANS. They

compared the interalar rim width between SLFIO without alar base cinch suture and V-Y closure and

CLFIO with alar base cinch suture and V-Y closure. During the first 6 months after surgery, the

interalar rim width showed a significant difference between the two groups (mean 1.92 mm),

increasing 1.04 mm on average in the CLFIO group but decreasing 2.27 mm in the SLFIO group.

Although there was no significant difference in interalar rim measurement after more than 12

postoperative months (mean 1.31 mm), differences in the timing of postoperative measurement

(mean 20 months and 15 months, respectively), the small sample size, and no alar base cinch suture

or V-Y closure in the SLFIO group might have affected this outcome. In a subsequent study, Mommaerts et al.4 evaluated profile changes in the nasal tip and

columello-labial region about 7-8 months after maxillary advancement and impaction surgery with

CLFIO involving partial or total removal of the nasal spine, alar base cinch suture, and V-Y closure or SLFIO.3 They found that subspinal osteotomy was not superior to CLFIO in respect to

minimizing nasal tip changes or obtaining control over the columello-labial angle, and that the

increase in nasal tip projection was caused by the advancing piriform aperture pushing on the alae,

not the nasal spine. Similarly, in the present study, there was no significant difference in nasal

projection between the CLFIO and SLFIO groups with respect to reduction of the piriform aperture

and alar base cinch suture and V-Y closure. However, transverse changes in nasal width and alar base width were significantly different in both groups. In questionnaire about patients’ satisfaction

after bimaxillary surgery, patients with good satisfaction of nasal aesthetics was more in SLFIO

group than CLFIO group. Becelli et al.11 applied subnasal, rather than SLFIO to avoid nasal tip upturning, alar base

widening, and upper lip flattening in anterosuperior repositioning of the maxilla. Their study

involved 10 patients who underwent CLFIO with alar base cinch suture and ANS reduction and 10

patients who underwent subnasal Le Fort I osteotomy to preserve the natural insertions of the

myrtiformis, transverse nasalis, and depressor septi muscles of the nasolabial region. In their

subnasal Le Fort I osteotomy procedure, to prevent postoperative widening of the nasal base, they

avoided detaching the muscular insertions of the perirhinal muscles by making a V-shaped

full-thickness incision in the anterior portion of the circumvestibular approach to preserve the soft

tissues under the piriform aperture. An osteotomy of the base of the piriform aperture including the

ANS can be performed without undermining the anterior mucoperiosteal flap or detaching the

harvested flap from the nasal septum. After repositioning of the maxilla, the flap is usually fixed in

the correct position with nonabsorbable or metallic wire stiches to avoid postoperative displacement.

A comparison of their two groups at 12 months after surgery on average revealed that preserving the

proper musculature insertions in subnasal Le Fort I osteotomy significantly reduced alar base

widening and nasal tip upturning. The subnasal Le Fort I osteotomy group with 4.0 mm anterior

repositioning and a mean 3.2 mm superior repositioning of the maxilla had mean changes in the alar

base width and nasal tip upturning of 0.54 mm and 0.71 mm, respectively. These mean changes were

the same as in our SLFIO group (0.54 mm and 0.73 mm, respectively). Because our SLFIO

procedure involved reduction of the piriform aperture, alar base cinch suture, and V-Y closure, the

difference from subnasal Le Fort I osteotomy is whether undermining the anterior mucoperiosteal

flap is performed or not.

More recently, Fernández Sanromán et al.1 evaluated changes in nasal profile after

subnasal Le Fort I osteotomy with alar base cinch suture and V-Y closure. Fifteen patients underwent

subnasal Le Fort I osteotomy with anterior repositioning (mean 7.5 mm, range 4-14 mm) and

inferior repositioning (mean 0.8 mm, range -3.5-2.6 mm) of the maxilla. There were no significant

changes in nose/alar base width, nasal bridge length, nasal tip protrusion, or nasal tip angle at 12

months after surgery. Although the changes they reported in nasal width, alar base width, and nasal

projection were smaller than those in the present study (0.1-0.2 mm vs 0.54-0.81 mm, respectively),

the differences might be due to inferior maxillary repositioning in subnasal Le Fort I osteotomy,

which can increase the volume of the nasal cavity.

Conclusion SLFIO with reduction of the piriform aperture, alar base cinch suture, and V-Y closure can be

recommended to prevent undesirable transverse soft tissue changes of the nose following anterior

repositioning of the maxilla.

Funding None.

Conflicts of interest None.

Ethical approval This study was reviewed and approved by the Institutional Review Board of Yokohama City

University (No. B160900017).

References 1.

Fernández Sanromán J, Costas López A, Fernández Ferro M, Arenaz Bua J, López de Sánchez

A. Subnasal modified Le Fort I osteotomy: indications and results. J Craniomaxillofac Surg

2014;42: 347-50.

2.

Liu X, Zhu S, Hu J. Modified versus classic alar base sutures after LeFort I osteotomy: a

systematic review. Oral Surg Oral Med Oral Pathol Oral Radiol 2014;117: 37-44.

3.

Mommaerts MY, Abeloos JV, De Clercq CA, Neyt LF. The effect of the subspinal Le Fort

I-type osteotomy on interalar rim width. Int J Adult Orthodon Orthognath Surg 1997;12:

95-100.

4.

Mommaerts MY, Lippens F, Abeloos JV, Neyt LF. Nasal profile changes after maxillary

impaction and advancement surgery. J Oral Maxillofac Surg 2000;58:470-5.

5.

Rauso R, Freda N, Curinga G, Del Pero C, Tartaro G. An alternative alar cinch suture. Eplasty

2010;10:e69.

6.

Maes F, Collignon A, Vandermeulen D, Marchal G, Suetens P. Multimodality image registration

by maximization of mutual information. IEEE Trans Med Imaging 1997;16:187-98.

7.

Lee JY, Kim YI, Hwang DS, Park SB. Effect of setback Le Fort I osteotomy on midfacial

soft-tissue changes as evaluated by cone-beam computed tomography superimposition for cases

of skeletal Class III malocclusion. Int J Oral Maxillofac Surg 2013;42:790-5.

8.

Bazina M, Cevidanes L, Ruellas A, et al. Precision and reliability of Dolphin 3-dimensional

voxel-based superimposition. Am J Orthod Dentofacial Orthop 2018;153:599-606.

9.

Rosen HM. Lip-nasal aesthetics following Le Fort I osteotomy. Plast Reconstr Surg 1988;81:

180-2.

10. Schendel SA, Williamson LW. Muscle reorientation following superior repositioning of the

maxilla. J Oral Maxillofac Surg 1983;41:235-40.

11. Becelli R, De Ponte FS, Fadda MT, Govoni FA, Iannetti G. Subnasal modified Le Fort I for

nasolabial aesthetics improvement. J Craniofac Surg 1996;7:399-402.

Figure legends

Fig. 1 Subspinal osteotomy in Le Fort I osteotomy

Red lines in A and B denote subspinal osteotomy lines.

Fig. 2 Alar base cinch suture A: Rauso et al.’s original method in which the suture is placed through the fibrous connective tissue

only.

B: Modified method of Rauso et al. used in the present study, in which the suture is placed through

the fibrous connective tissue and lesser alar cartilage.

Fig. 3 Landmarks and measurement sites

A: Frontal landmarks and measurement sites.

B: Lateral landmarks and measurement sites.

Landmarks: alare (Al), alar curvature (Ac), soft tissue glabella (Gs), soft tissue nasion (Ns),

pronasale (Prn), columella (Cm), subnasale (Sn), and labrale superior (Ls). Measurement sites: ① nasal width (Al-Al), ② alar base width (Ac-Ac), ③ nasal length (N-Prn), ④ nasal projection (perpendicular distance), ⑤ nasofrontal angle (Gl-N-Prn), ⑥ nasal tip angle (N-Prn-Sn), and ⑦ nasolabial angle (Cm-Sn-Ls).

Table 1. Questionnaire about patients’ satisfaction after bimaxillary surgery

Questions

Assessment

1. How would you assess your facial aesthetics after surgery?

Good

Fair

Poor

2. How would you assess your nasal aesthetics after surgery?

Good

Fair

Poor

Table 2. Maxillary movements following orthognathic surgery with CLFIO or SLFIO CLFIO (mm)

Point Pt A

PNS

Is

ANS

SLFIO (mm)

p -value

Mean

SD

Mean

SD

x

-0.42

0.77

0.18

1.08

0.07

y

2.64

1.36

2.83

0.86

0.47

z

1.72

1.58

1.91

1.44

0.84

x

-0.27

0.61

-0.34

0.6

0.61

y

3.48

2.03

2.56

1.35

0.26

z

2.41

0.98

2.94

1.55

0.49

x

-0.47

0.70

0.26

1.45

0.07

y

2.61

1.80

1.49

2.31

0.10

z

0.96

1.86

0.87

1.93

0.76

x

-0.28

0.75

0.04

0.96

0.13

y

2.39

1.42

1.16

0.75

p < 0.01

z

1.27

1.67

0.26

0.85

p < 0.05

p-values determined using Wilcoxon’s rank sum test. Is, incision superius; PNS, posterior nasal spine; Pt A, point A; x, transverse axis; y, sagittal axis; z, vertical axis

Table 3. Changes in nasal morphology following orthognathic surgery with CLFIO or SLFIO

Measurement

CLFIO

SLFIO

p -value

Mean

SD

Mean

SD

Nasal width (mm)

1.46

1.08

0.81

0.64

p < 0.01

Alar base width (mm)

1.99

1.40

0.54

0.67

p < 0.01

Nasal length (mm)

-0.62

0.78

-0.07

0.42

p < 0.05

Nasal tip projection (mm)

0.70

0.85

0.73

0.49

0.99

Nasofrontal angle (°)

-1.35

2.89

-0.10

2.03

p < 0.05

Nasal tip angle (°)

1.25

3.09

-0.08

2.00

0.19

Nasolabial angle (°)

1.55

8.53

0.84

3.72

0.98

p-values determined using Wilcoxon’s rank sum test