CLINICAL STUDY
Assessment of Orbital Volume in Frontofacial Advancements Rodrigo Badotti Antunes, MD, Anderson Aparecido Camilo, Eng,y Airton Moreira da Silva, Eng,y Jorge Vicente Lopes da Silva, Eng,y and Nivaldo Alonso, PhD Objectives: The objective of this study was to evaluate the variation of the orbital volume and the correlation with the magnitude of craniofacial advances as well as demonstrate its effectiveness through comparisons with normal levels of orbital volumes. Introduction: Syndromic craniofacial synostosis is characterized by cranial morphological alterations and hypoplasia of the midface that may result in obstructive sleep apnea and exorbitism; these effects are indications of surgical treatment. The gradual advancement of tissues is the surgical treatment to correct accentuated exorbitisms and jaw retrusions. Methods: This was a retrospective study by review of medical records and tomographic examinations of 20 patients submitted to distraction osteogenesis between 2001 and 2012, who were divided into 2 groups: groups MB and LF with 11 and 9 patients, who underwent frontofacial or Le Fort III osteotomy. The orbit volume was measured with the InVesalius and Magics software, and facial advancements with Rhinoceros software. Statistical analyses were conducted using Student t test and analysis of variance. Results: Patients’ ages ranged from 6 to 29 years. Group MB showed an increase of 8.94 and 9.84 mm3 in the right and left orbit volume variation, whereas group LF presented 5.70 and 5.77 mm3. The average advancements in the right and left orbits were 11.36 3.80 and 11.11 3.45 mm in group LF, respectively, and 14.22 4.12 and 14.48 4.49 mm in group MB. Conclusions: Exorbitism was satisfactorily treated. The correlation was proportional in group LF and group MB. There was normalization of orbital volume compared with normal levels of orbital volumes.
sutures leading to morphological changes that impose serious deficiencies in the growth of the midface or cranium.1– 7 In addition to aesthetic defects, patients with syndromic CS have shallow orbits and substantial reduction in the orbit volume, leading to ocular alterations such as exorbitism, lack of eye protection, divergent strabismus, ocular proptosis, optic atrophy, and even blindness. The presence of severe jaw hypoplasia in these patients is also responsible for respiratory symptoms (obstructive sleep apnea hypopnea syndrome).2,3,6–8 These clinical abnormalities and their adverse consequences are absolute indications for surgical treatment. Distraction osteogenesis has been used successfully in the correction of craniofacial deformities (congenital or acquired) allowing the elongation of both bones and soft tissues. The use of this surgical technique has been widespread in large centers and is currently considered the treatment of choice for patients with syndromic CS.2,3,9–14 The objectives of the present study were to evaluate patients with syndromic craniofaciosynostosis submitted to craniofacial osteotomies (Le Fort III and monobloc) using distractor devices, to the following parameters: (a) increase and variation of orbital volumes, (b) magnitude of craniofacial advances and its vectors, (c) correlation between the variation of the orbital volumes and craniofacial advances, and (d) effectiveness of craniofacial advances through comparisons between normal levels of orbital volumes.
METHODS This was a retrospective study conducted in the Craniomaxillofacial Surgery Section at the Department of Plastic Surgery and Burns of the Hospital das Clı´nicas, Medical School at Sa˜o Paulo University.
Key Words: Craniofaciosynostosis, exorbitism, monobloc, Le Fort III, orbital volume (J Craniofac Surg 2015;26: 843–848)
S
yndromic craniofacial synostosis (CS) is a congenital disorder associated with mutations of the FGFR1, FGFR2, and FGFR3 genes. It is characterized by the premature fusion of craniofacial From the Craniofacial Surgery Unit, Division of Plastic Surgery, University of Sa˜o Paulo Medical School, Sa˜o Paulo, and yCentre for Information Technology Renato Archer, Campinas, Sa˜o Paulo, Brazil. Received September 9, 2014. Accepted for publication January 15, 2015. Address correspondence and reprint requests to Nivaldo Alonso, PhD, Rua Afonso Bra´s, 473-cj. 65-Vila Nova Conceic¸a˜o, Sa˜o Paulo, Sa˜o Paulo, Brazil CEP 04511–011; E-mail: [email protected] No funding was received for this study. The authors report no conflicts of interest. Copyright # 2015 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000001576
The Journal of Craniofacial Surgery
FIGURE 1. Facial photograph showing exorbitism correction after monobloc osteotomy. Preoperative aspect (A, B) and Postoperative aspect (C, D).
Volume 26, Number 3, May 2015
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Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
Antunes et al
The Journal of Craniofacial Surgery
Volume 26, Number 3, May 2015
FIGURE 3. Segmentation orbital wall. A, Right orbit. B, Left orbit.
the three-dimensional model is generated and saved in STL (stereolithography) format (Figs. 3 and 4). The three-dimensional model is imported into Magics software, where the closure of all bone discontinuities is performed, including anterior and posterior opening of the orbital cavity, both the right and left orbit, preoperatively and postoperatively (Figs. 5 and 6). Thus, the model generates the orbital cavity whose volume is measured automatically by the software (Figs. 7 and 8). FIGURE 2. Images are imported into the software InVesalius in DICOM format.
Twenty patients with CS were selected between 2001 and 2012 for the evaluation of the orbit volume variation and quantitative facial advancements and their vectors, preoperatively and postoperatively. These patients were divided into 2 groups. Group MB consisted of 11 patients who underwent monobloc frontofacial osteotomy, and group LF consisted of 9 patients who underwent Le Fort III osteotomy (Fig. 1). The distractor used was the RED (Rigid External Device; KLS Martin, Tuttlingen, Germany) or internal distractor (KLS Martin). All patients presented exorbitism and premature closure of cranial sutures, including those at the base of the cranium. The Le Fort III osteotomy was performed in patients with exorbitism and accentuated jaw hypoplasia, whereas monobloc frontofacial osteotomy was performed in the patients with frontal retrusion associated with a small projection of the superior orbital margin. The protocol used to activate distraction was initiated after a latency period of 5 days, at a rate of 1 mm/d, and ending after obtaining the proper relationship between orbit content and continent and occlusal overcorrection. The restraining period lasted 6 to 8 weeks.
Measures of Orbital Volumes The measurement of the orbit volume was performed through the segmentation of medical images in the InVesalius software (CTI–Renato Archer Information Technology Center) and threedimensional modeling in the Magics software (Materialise, Leuven, Belgium). The images are imported into the software InVesalius in DICOM (digital imaging and communications in medicine) format (Fig. 2). For the segmentation of bony orbital walls, the HU scale (Hounsfield unit) was used, with a threshold of þ400 HU or more in the axial, coronal, and sagittal planes (Table 1). After the segmentation,
Measure of Craniofacial Advances The magnitude of craniofacial advancements and their vectorial analyses were carried out with the Rhinoceros software (Robert McNeel & Associates, Seattle, WA). We determine the craniometric points of interest to the study (right orbital, orbital left, nasion, subspinale) (Fig. 9). Reference planes originating in sella were created (axial, coronal, and sagittal) (Fig. 10). By superposition of these plans in the preoperative and postoperative period, we performed the steps between craniometric points by differential form (Fig. 11). All measurements were conducted by the authors of the study with the aid of 2 engineering professionals who participated in the research. Both preoperative and postoperative orbit volumes were compared with the normal orbit volume published by Bentley et al15,16 (Table 2).
Three-Dimensional Tomographic Evaluation Each patient underwent 2 tomographic examinations: one preoperatively and one postoperatively (when the restraining period was completed and up to 12 months after surgery). Objectively, three-dimensional evaluations were carried out to determine the following parameters: postoperative orbital volume, the variation of the orbital volume, postoperative orbital symmetry, the magnitude of craniofacial advancement and its vectors, and the comparison of orbital volumes obtained at normal rates of orbital volumes.
Statistical Analysis The Student t test was used to compare the average orbit volume variation increase between groups; the double-factor repeatedmeasures analysis of variance was used for comparisons between
TABLE 1. Scale Hounsfield Units (HU) Substance Air Fat Water Muscle Contrast Bone
844
HU 1000 120 0 þ40 þ130 þ400
FIGURE 4. Completion of the orbital wall segmentation—three-dimensional model is generated. A, Right orbit. B, Left orbit.
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2015 Mutaz B. Habal, MD
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The Journal of Craniofacial Surgery
Volume 26, Number 3, May 2015
Frontofacial Advancement Orbital Volume
FIGURE 5. Three-dimensional modeling—Magics software. A, Discontinuities in bony orbital walls. B, Selected and expanded bone discontinuity. C, Deleted expanded area. D, Bone discontinuity filled.
groups and between times of average volume and of craniofacial advancements. To verify whether the proportional increase between craniofacial advancements and the variation of the orbital volume was positive, the Pearson correlation was used. The probability error type I (a) of 0.05 was considered. Statistical analyses were performed using SPSS software version 21 (IBM, Armond, NY). Patient identity remained strictly confidential.
RESULTS In group MB, 6 patients were females, and 5 were males, who presented with Crouzon syndrome (n ¼ 7), Apert syndrome (n ¼ 2), and others (n ¼ 2). In group LF, 2 patients were males and 7 were females, who presented with Crouzon syndrome (n ¼ 4), Apert syndrome (n ¼ 4), and others (n ¼ 1). Two patients used external distractors (RED), and 9 used internal distractors in group MB, whereas in group LF, 8 patients used the RED distractor, and 1 used the internal distractor. The average age of patients who underwent the surgical procedure was 21 years in group LF (ranging between 12.82 and 26.15 years) and 10 years in group MB (ranging between 3.39 and 13.77 years). The volume variation was significantly higher in group MB (70.06% 26.04% and 82.22% 36.01% average variation for the
FIGURE 6. Three-dimensional modeling—Magics software. Separate orbits of the skull after the closure of all bone discontinuities.
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2015 Mutaz B. Habal, MD
FIGURE 7. Preoperative aspect; three-dimensional modeling—Magics software. A, Three-dimensional reconstructions of the cranium. B, Right orbital cavity. C, Left orbital cavity.
right and left orbits, respectively) compared with group LF (29.21% 16.39% and 29.20% 17.00% average variation for the right and left orbits, respectively), for both right and left orbits (Fig. 12). The preoperative average volume for the right and left orbits in group LF were 19.60 2.22 and 19.81 2.79 mm3 (P < 0.001), respectively, and postoperative average volumes were 25.30 3.86 and 25.58 4.66 mm3, respectively. The preoperative average volume for the right and left orbits in group MB were 13.10 2.90 and 12.61 2.69 mm3 (P < 0.001), respectively, and postoperative average volumes were 22.05 4.87 and 22.46 4.22 mm3, respectively (Figs. 13 and 14). The average horizontal advancement, in group LF, for the right and left orbits was 8.99 4.08 and 8.71 4.25 mm, respectively. The average horizontal advancement in group MB for the right and
FIGURE 8. Postoperative aspect; three-dimensional modeling—Magics software. A, Three-dimensional reconstructions of the cranium. B, Right orbital cavity. C, Left orbital cavity.
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FIGURE 9. Facial advancements—Rhinoceros software. Craniometric points (yellow dots) using the Rhinoceros software: nasion (N), right orbital (OD), left orbital (OE), and subspinale (A).
left orbits was 13.53 4.09 and 14.23 4.62 mm, respectively (Fig. 15). The average vertical advancement, in group LF, for the right and left orbits was 5.82 3.27 and 5.79 2.10 mm, respectively. The average vertical advancement, in group MB, for the right and left orbits was 3.22 2.72 and 1.61 1.51 mm, respectively (Fig. 16). The correlation between the resulting orbit advancement and the difference in orbit volume was significant in group LF and the left orbit in group MB (Figs. 17 and 18).
DISCUSSION Bone distraction of the midface is currently considered the surgical procedure of choice for the treatment of syndromic CS, and it is being widely used in global reference centers.12,14 The number of publications regarding measurements of orbit volume to evaluate surgical treatment of exorbitism in patients with syndromic CS is scarce.4,6,17– 19 In this study, when the volumetric measurements between groups were compared, a greater orbit volume (preoperatively and postoperatively) was observed in group LF for the left and right orbits. According to our protocol, patients who underwent surgery in group LF were older than those in group MB. At this age, craniofacial growth is more advanced and more mature, which could explain the higher preoperative and postoperative isolated volumetric measurements in group LF than in group MB. It is noteworthy that, in our results, we observe a lower orbit volume variation in group LF. As expected, in more dramatic clinical situations, with severe exorbitisms and jaw retrusions, a higher average value would be anticipated in group MB compared with group LF. This may have resulted from wider orbital osteotomies involving all walls (circumferential) associated with greater magnitude in horizontal advancements in the fronto-orbital segment promoted by the superior traction point during the period of distractor activation, in both right and left orbits. Our results showed not only an improvement in exorbitism, in both groups, but also a significant increase in the orbital cavity, as reported in other studies, where patients were submitted to Le Fort III6,18 or monobloc4 osteotomy.
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FIGURE 11. Facial advancements—Rhinoceros software. Superposition of three-dimensional images preoperative (orange) and postoperative (pink). Facial advancements and their vectorial analyses were carried out with the Rhinoceros software.
During the analyses of our results of exorbitism correction, the results of our group of patients taking as references the values of normal orbital volumes published by Bentley et al15,16 were compared, which may be used as reference for comparative studies of conditions that affect orbital growth. Evaluating our results with normal values, satisfactory postoperative results were evidenced, with normalization of the orbit volume for both group LF as for group MB. For the improvement of the symptoms related to exorbitism, more significant vertical component has been verified for the resulting craniofacial advance of group LF, whereas to increase the orbital cavity in group MB, the resulting movement presented in the horizontal component, the greatest magnitude of the average progress, obtained in our study by frontofacial in monobloc osteotomy. With these results, we found that the orbital volumes were completely restored, and consequently, their eye symptoms related to exorbitism were resolved. Thus, the protection of the eyeball was obtained with the technique used for both groups when compared with normal values of the orbital volumes, demonstrating the effectiveness of the surgical procedure. During this study, interesting results were found related to craniofacial linear advances, which served as the basis for the correlation with the variation of orbital volumes in each group of patients in order to evaluate the results and determine surgical parameters to gradual bone stretching with use of distractor devices. We observed in our study, group LF, an increase of 1 mm resulting in the advancement of the midface; the increase in orbital volume was 0.488 mm3 to right orbit and 0.576 mm3 to left orbit. As for group MB, for this relationship of proportionality we showed that, for an increase of 1 mm resulting in the advancement of the midface, the increase in orbital volume was 0.707 mm3 to right orbit and 0.731 mm3 to left orbit. TABLE 2. Normal Changes in Orbital Volume (Bentley et al15,16) Factor Left orbit Mean volume (cm3) Boys Girls P Right orbit Mean volume (cm3) Boys Girls P
FIGURE 10. Facial advancements—Rhinoceros software. Overview of the superposition of the sagittal (black with red outline), axial (black with green outline), and coronal (blue) planes, using the Rhinoceros software.
0–5 y
5–10 y
10–15 y
17.05 14.51 0.10
22.70 21.88 0.75
27.62 25.43 0.29
18.18 14.45 0.04
23,58 22.65 0.65
28.34 26.02 0.31
Comparison of left and right orbital volumes in boys and girls.
Probability values were determined using a t test.
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2015 Mutaz B. Habal, MD
Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery
Volume 26, Number 3, May 2015
FIGURE 12. Average volume variation in group LF and group MB. Above, Right orbit. Below, Left orbit.
Knowing that with the advance of the midface is obtained proportional to the increase in orbital volume in the above values, we can better evaluate patients in the preoperative period and thus better define the surgical planning, having an estimate of how much we shall proceed to the face with the use of distractor devices to obtain increase in the orbital volume compatible with indexes of normality. In the postoperative period, these parameters can also help us in situations that eventual surgical complications and/or
Frontofacial Advancement Orbital Volume
FIGURE 14. Comparing the volume obtained postoperatively in relation to Bentley et al.15,16 Above, Right orbit. Below, Left orbit.
exuberant edema in the postoperative period may hinder the clinical evaluation of the surgeon in determining the exact time of completion of the distractor activation period, helping prevent unwanted results, residual exorbitism, or postoperative enophthalmos, coming to characterize failure of treatment. Therefore, in order to establish a protocol for the advancement of the midface and determine the exact moment for the completion of the activation period, we infer that the gradual bone elongation with the use of distractor devices should be terminated when the normalization of the orbit volume occurs, for both group LF and group MB; however, group LF found that it is necessary to have small variations in orbital volume, whereas large variations (70%– 80%) in group MB are necessary for obtaining a normal volume.
CONCLUSIONS (a) There was significant increase in the orbital cavity for both group LF and group MB. The average variation of the orbital volume to reach indexes of normality was higher in group MB. (b) In the quantitative and vectorial evaluation of the craniofacial movements, the magnitude of the vertical component was greater in
FIGURE 13. Comparing the volume obtained preoperatively regarding Bentley et al.15,16 Above, Right orbit. Below, Left orbit.
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2015 Mutaz B. Habal, MD
FIGURE 15. Average horizontal advancement, in group LF and group MB, for the right and left orbits.
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FIGURE 16. Average vertical advancement, in group LF and group MB, for the right and left orbits.
FIGURE 17. Correlation of orbital volume variation and resulting advance orbits, right (A ¼ LF and B ¼ MB).
FIGURE 18. Correlation of orbital volume variation and resulting advance orbits, left (A ¼ LF and B ¼ MB).
group LF, whereas the magnitude of the horizontal component was greater in group MB. (c) The correlation between craniofacial advancements and the variation of orbital volumes showed proportional greater increase in group MB. (d) The surgical procedure was effective to both group LF as for group MB, because normalization of the orbit volume when compared with the index of normality was found.
REFERENCES 1. Shetye PR, Davidson EH, Sorkin M, et al. Evaluation of three surgical techniques for advancement of the midface in growing children with syndromic craniosynostosis. Plast Reconstr Surg 2010;126:982–993
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2. Cruz AAV, Akaishi PMS, Arnaud E, et al. Exorbitism correction of faciocraniosynostoses by monobloc frontofacial advancement with distraction osteogenesis. J Craniofac Surg 2007;18:355–360 3. Meling TR, Due-Tonnessen BJ, Hogevold HE, et al. Monobloc distraction osteogenesis in pediatric patients with severe syndromal craniosynostosis. J Craniofac Surg 2004;15:990–1000 4. Bender CA, Veneman W, Veenland JF, et al. Orbital aspects following monobloc advancement in syndromic craniosynostosis. J Craniomaxillofac Surg 2013;41:e146–e153 5. Oliveira NAJ. Estudo molecular das craniossinostoses sindroˆmicas: Crouzon, Pfeiffer e Saethre-Chotzen. Dissertac¸a˜o para a otenc¸a˜o do Tı´tulo de Mestre em Cieˆncias, apresentada ao Instituto de Biocieˆncias da Universidade de Sa˜o Paulo, na A´rea de Biologia/ Gene´tica 2006 6. Nout E, van Bezooijen JS, Koudstaal MJ, et al. Orbital change following Le Fort III advancement in syndromic craniosynostosis: quantitative evaluation of orbital volume, infra-orbital rim and globe position. J Craniomaxillofac Surg 2012;40:223–228 7. Alonso N, Matushita H, Goldenberg DC, et al. Idade e indicac¸o˜es de osteotomias para avanc¸o frontofacial em pacientes com craniossinostoses sindroˆmicas. Rev Bras Cir Plast 2012;27: 223–226 8. Alonso N, Munhoz AM, Fogac¸a W, et al. Midfacial advancement by bone distraction for treatment of craniofacial deformities. J Craniofac Surg 1998;9:114–118 discussion 119–122 9. Shetye PR, Kapadia H, Grayson BH, et al. A 10-year study of skeletal stability and growth of the midface following Le Fort III advancement in syndromic craniosynostosis. Plast Reconstr Surg 2010;126:973–981 10. Swennen G, Dempf R, Schliephake H. Cranio-facial distractioosteogenesis: a review of the literature. Part II: experimental studies. Int J Oral Maxillofac Surg 2002;31:123–135 11. Swennen G, Schliephake H, Dempf R, et al. Craniofacial distraction osteogenesis: a review of the literature. Part 1: clinical studies. Int J Oral Maxillofac Surg 2001;30:89–103 12. Satoh K, Mitsukawa N, Hosaka Y. Dual midfacial distraction osteogenesis: Le Fort III minus I and Le Fort I for syndromic craniosynostosis. Plast Reconstr Surg 2003;111:1019–1028 13. Witherow H, Dunaway D, Evans R, et al. Functional outcomes in monobloc advancement by distraction using the rigid external distractor device. Plast Reconstr Surg 2008;121:1311–1322 14. Lima DSC, Alonso N, Caˆmara PRP, et al. Evaluation of cephalometric points in midface bone lengthening with the use of a rigid external device in syndromic craniosynostosis patients. Braz J Otorhinolaryngol 2009;75:395–406 15. Bentley RP, Sgouros S, Natarajan K, et al. Normal changes in orbital volume during childhood. J Neurosurg 2002;96:742–746 16. Bentley RP, Sgouros S, Natarajan K, et al. Changes in orbital volume during childhood in cases of craniosynostosis. J Neurosurg 2002;96:746–747 17. Imai K, Fujimoto T, Takahashi M, et al. Preoperative and Postoperative Orbital Volume in Patients With Crouzon and Apert syndrome. J Craniofac Surg 2013;24:191–194 18. Festa F, Pagnoni M, Valerio R, et al. Orbital volume and surface after Le Fort III advancement in syndromic craniosynostosis. J Craniofac Surg 2012;23:789–792 19. Forbes G, Gehring DG, Gorman CA, et al. Volume measurements of normal orbital structures by computed tomographic analysis. AJR Am J Roentgenol 1985;145:149–154
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Assessment of Orbital Volume in Frontofacial Advancements Rodrigo Badotti Antunes, MD, Anderson Aparecido Camilo, Eng,y Airton Moreira da Silva, Eng,y Jorge Vicente Lopes da Silva, Eng,y and Nivaldo Alonso, PhD Objectives: The objective of this study was to evaluate the variation of the orbital volume and the correlation with the magnitude of craniofacial advances as well as demonstrate its effectiveness through comparisons with normal levels of orbital volumes. Introduction: Syndromic craniofacial synostosis is characterized by cranial morphological alterations and hypoplasia of the midface that may result in obstructive sleep apnea and exorbitism; these effects are indications of surgical treatment. The gradual advancement of tissues is the surgical treatment to correct accentuated exorbitisms and jaw retrusions. Methods: This was a retrospective study by review of medical records and tomographic examinations of 20 patients submitted to distraction osteogenesis between 2001 and 2012, who were divided into 2 groups: groups MB and LF with 11 and 9 patients, who underwent frontofacial or Le Fort III osteotomy. The orbit volume was measured with the InVesalius and Magics software, and facial advancements with Rhinoceros software. Statistical analyses were conducted using Student t test and analysis of variance. Results: Patients’ ages ranged from 6 to 29 years. Group MB showed an increase of 8.94 and 9.84 mm3 in the right and left orbit volume variation, whereas group LF presented 5.70 and 5.77 mm3. The average advancements in the right and left orbits were 11.36 3.80 and 11.11 3.45 mm in group LF, respectively, and 14.22 4.12 and 14.48 4.49 mm in group MB. Conclusions: Exorbitism was satisfactorily treated. The correlation was proportional in group LF and group MB. There was normalization of orbital volume compared with normal levels of orbital volumes.
sutures leading to morphological changes that impose serious deficiencies in the growth of the midface or cranium.1– 7 In addition to aesthetic defects, patients with syndromic CS have shallow orbits and substantial reduction in the orbit volume, leading to ocular alterations such as exorbitism, lack of eye protection, divergent strabismus, ocular proptosis, optic atrophy, and even blindness. The presence of severe jaw hypoplasia in these patients is also responsible for respiratory symptoms (obstructive sleep apnea hypopnea syndrome).2,3,6–8 These clinical abnormalities and their adverse consequences are absolute indications for surgical treatment. Distraction osteogenesis has been used successfully in the correction of craniofacial deformities (congenital or acquired) allowing the elongation of both bones and soft tissues. The use of this surgical technique has been widespread in large centers and is currently considered the treatment of choice for patients with syndromic CS.2,3,9–14 The objectives of the present study were to evaluate patients with syndromic craniofaciosynostosis submitted to craniofacial osteotomies (Le Fort III and monobloc) using distractor devices, to the following parameters: (a) increase and variation of orbital volumes, (b) magnitude of craniofacial advances and its vectors, (c) correlation between the variation of the orbital volumes and craniofacial advances, and (d) effectiveness of craniofacial advances through comparisons between normal levels of orbital volumes.
METHODS This was a retrospective study conducted in the Craniomaxillofacial Surgery Section at the Department of Plastic Surgery and Burns of the Hospital das Clı´nicas, Medical School at Sa˜o Paulo University.
Key Words: Craniofaciosynostosis, exorbitism, monobloc, Le Fort III, orbital volume (J Craniofac Surg 2015;26: 843–848)
S
yndromic craniofacial synostosis (CS) is a congenital disorder associated with mutations of the FGFR1, FGFR2, and FGFR3 genes. It is characterized by the premature fusion of craniofacial From the Craniofacial Surgery Unit, Division of Plastic Surgery, University of Sa˜o Paulo Medical School, Sa˜o Paulo, and yCentre for Information Technology Renato Archer, Campinas, Sa˜o Paulo, Brazil. Received September 9, 2014. Accepted for publication January 15, 2015. Address correspondence and reprint requests to Nivaldo Alonso, PhD, Rua Afonso Bra´s, 473-cj. 65-Vila Nova Conceic¸a˜o, Sa˜o Paulo, Sa˜o Paulo, Brazil CEP 04511–011; E-mail: [email protected] No funding was received for this study. The authors report no conflicts of interest. Copyright # 2015 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000001576
The Journal of Craniofacial Surgery
FIGURE 1. Facial photograph showing exorbitism correction after monobloc osteotomy. Preoperative aspect (A, B) and Postoperative aspect (C, D).
Volume 26, Number 3, May 2015
843
Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
Antunes et al
The Journal of Craniofacial Surgery
Volume 26, Number 3, May 2015
FIGURE 3. Segmentation orbital wall. A, Right orbit. B, Left orbit.
the three-dimensional model is generated and saved in STL (stereolithography) format (Figs. 3 and 4). The three-dimensional model is imported into Magics software, where the closure of all bone discontinuities is performed, including anterior and posterior opening of the orbital cavity, both the right and left orbit, preoperatively and postoperatively (Figs. 5 and 6). Thus, the model generates the orbital cavity whose volume is measured automatically by the software (Figs. 7 and 8). FIGURE 2. Images are imported into the software InVesalius in DICOM format.
Twenty patients with CS were selected between 2001 and 2012 for the evaluation of the orbit volume variation and quantitative facial advancements and their vectors, preoperatively and postoperatively. These patients were divided into 2 groups. Group MB consisted of 11 patients who underwent monobloc frontofacial osteotomy, and group LF consisted of 9 patients who underwent Le Fort III osteotomy (Fig. 1). The distractor used was the RED (Rigid External Device; KLS Martin, Tuttlingen, Germany) or internal distractor (KLS Martin). All patients presented exorbitism and premature closure of cranial sutures, including those at the base of the cranium. The Le Fort III osteotomy was performed in patients with exorbitism and accentuated jaw hypoplasia, whereas monobloc frontofacial osteotomy was performed in the patients with frontal retrusion associated with a small projection of the superior orbital margin. The protocol used to activate distraction was initiated after a latency period of 5 days, at a rate of 1 mm/d, and ending after obtaining the proper relationship between orbit content and continent and occlusal overcorrection. The restraining period lasted 6 to 8 weeks.
Measures of Orbital Volumes The measurement of the orbit volume was performed through the segmentation of medical images in the InVesalius software (CTI–Renato Archer Information Technology Center) and threedimensional modeling in the Magics software (Materialise, Leuven, Belgium). The images are imported into the software InVesalius in DICOM (digital imaging and communications in medicine) format (Fig. 2). For the segmentation of bony orbital walls, the HU scale (Hounsfield unit) was used, with a threshold of þ400 HU or more in the axial, coronal, and sagittal planes (Table 1). After the segmentation,
Measure of Craniofacial Advances The magnitude of craniofacial advancements and their vectorial analyses were carried out with the Rhinoceros software (Robert McNeel & Associates, Seattle, WA). We determine the craniometric points of interest to the study (right orbital, orbital left, nasion, subspinale) (Fig. 9). Reference planes originating in sella were created (axial, coronal, and sagittal) (Fig. 10). By superposition of these plans in the preoperative and postoperative period, we performed the steps between craniometric points by differential form (Fig. 11). All measurements were conducted by the authors of the study with the aid of 2 engineering professionals who participated in the research. Both preoperative and postoperative orbit volumes were compared with the normal orbit volume published by Bentley et al15,16 (Table 2).
Three-Dimensional Tomographic Evaluation Each patient underwent 2 tomographic examinations: one preoperatively and one postoperatively (when the restraining period was completed and up to 12 months after surgery). Objectively, three-dimensional evaluations were carried out to determine the following parameters: postoperative orbital volume, the variation of the orbital volume, postoperative orbital symmetry, the magnitude of craniofacial advancement and its vectors, and the comparison of orbital volumes obtained at normal rates of orbital volumes.
Statistical Analysis The Student t test was used to compare the average orbit volume variation increase between groups; the double-factor repeatedmeasures analysis of variance was used for comparisons between
TABLE 1. Scale Hounsfield Units (HU) Substance Air Fat Water Muscle Contrast Bone
844
HU 1000 120 0 þ40 þ130 þ400
FIGURE 4. Completion of the orbital wall segmentation—three-dimensional model is generated. A, Right orbit. B, Left orbit.
#
2015 Mutaz B. Habal, MD
Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery
Volume 26, Number 3, May 2015
Frontofacial Advancement Orbital Volume
FIGURE 5. Three-dimensional modeling—Magics software. A, Discontinuities in bony orbital walls. B, Selected and expanded bone discontinuity. C, Deleted expanded area. D, Bone discontinuity filled.
groups and between times of average volume and of craniofacial advancements. To verify whether the proportional increase between craniofacial advancements and the variation of the orbital volume was positive, the Pearson correlation was used. The probability error type I (a) of 0.05 was considered. Statistical analyses were performed using SPSS software version 21 (IBM, Armond, NY). Patient identity remained strictly confidential.
RESULTS In group MB, 6 patients were females, and 5 were males, who presented with Crouzon syndrome (n ¼ 7), Apert syndrome (n ¼ 2), and others (n ¼ 2). In group LF, 2 patients were males and 7 were females, who presented with Crouzon syndrome (n ¼ 4), Apert syndrome (n ¼ 4), and others (n ¼ 1). Two patients used external distractors (RED), and 9 used internal distractors in group MB, whereas in group LF, 8 patients used the RED distractor, and 1 used the internal distractor. The average age of patients who underwent the surgical procedure was 21 years in group LF (ranging between 12.82 and 26.15 years) and 10 years in group MB (ranging between 3.39 and 13.77 years). The volume variation was significantly higher in group MB (70.06% 26.04% and 82.22% 36.01% average variation for the
FIGURE 6. Three-dimensional modeling—Magics software. Separate orbits of the skull after the closure of all bone discontinuities.
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2015 Mutaz B. Habal, MD
FIGURE 7. Preoperative aspect; three-dimensional modeling—Magics software. A, Three-dimensional reconstructions of the cranium. B, Right orbital cavity. C, Left orbital cavity.
right and left orbits, respectively) compared with group LF (29.21% 16.39% and 29.20% 17.00% average variation for the right and left orbits, respectively), for both right and left orbits (Fig. 12). The preoperative average volume for the right and left orbits in group LF were 19.60 2.22 and 19.81 2.79 mm3 (P < 0.001), respectively, and postoperative average volumes were 25.30 3.86 and 25.58 4.66 mm3, respectively. The preoperative average volume for the right and left orbits in group MB were 13.10 2.90 and 12.61 2.69 mm3 (P < 0.001), respectively, and postoperative average volumes were 22.05 4.87 and 22.46 4.22 mm3, respectively (Figs. 13 and 14). The average horizontal advancement, in group LF, for the right and left orbits was 8.99 4.08 and 8.71 4.25 mm, respectively. The average horizontal advancement in group MB for the right and
FIGURE 8. Postoperative aspect; three-dimensional modeling—Magics software. A, Three-dimensional reconstructions of the cranium. B, Right orbital cavity. C, Left orbital cavity.
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FIGURE 9. Facial advancements—Rhinoceros software. Craniometric points (yellow dots) using the Rhinoceros software: nasion (N), right orbital (OD), left orbital (OE), and subspinale (A).
left orbits was 13.53 4.09 and 14.23 4.62 mm, respectively (Fig. 15). The average vertical advancement, in group LF, for the right and left orbits was 5.82 3.27 and 5.79 2.10 mm, respectively. The average vertical advancement, in group MB, for the right and left orbits was 3.22 2.72 and 1.61 1.51 mm, respectively (Fig. 16). The correlation between the resulting orbit advancement and the difference in orbit volume was significant in group LF and the left orbit in group MB (Figs. 17 and 18).
DISCUSSION Bone distraction of the midface is currently considered the surgical procedure of choice for the treatment of syndromic CS, and it is being widely used in global reference centers.12,14 The number of publications regarding measurements of orbit volume to evaluate surgical treatment of exorbitism in patients with syndromic CS is scarce.4,6,17– 19 In this study, when the volumetric measurements between groups were compared, a greater orbit volume (preoperatively and postoperatively) was observed in group LF for the left and right orbits. According to our protocol, patients who underwent surgery in group LF were older than those in group MB. At this age, craniofacial growth is more advanced and more mature, which could explain the higher preoperative and postoperative isolated volumetric measurements in group LF than in group MB. It is noteworthy that, in our results, we observe a lower orbit volume variation in group LF. As expected, in more dramatic clinical situations, with severe exorbitisms and jaw retrusions, a higher average value would be anticipated in group MB compared with group LF. This may have resulted from wider orbital osteotomies involving all walls (circumferential) associated with greater magnitude in horizontal advancements in the fronto-orbital segment promoted by the superior traction point during the period of distractor activation, in both right and left orbits. Our results showed not only an improvement in exorbitism, in both groups, but also a significant increase in the orbital cavity, as reported in other studies, where patients were submitted to Le Fort III6,18 or monobloc4 osteotomy.
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FIGURE 11. Facial advancements—Rhinoceros software. Superposition of three-dimensional images preoperative (orange) and postoperative (pink). Facial advancements and their vectorial analyses were carried out with the Rhinoceros software.
During the analyses of our results of exorbitism correction, the results of our group of patients taking as references the values of normal orbital volumes published by Bentley et al15,16 were compared, which may be used as reference for comparative studies of conditions that affect orbital growth. Evaluating our results with normal values, satisfactory postoperative results were evidenced, with normalization of the orbit volume for both group LF as for group MB. For the improvement of the symptoms related to exorbitism, more significant vertical component has been verified for the resulting craniofacial advance of group LF, whereas to increase the orbital cavity in group MB, the resulting movement presented in the horizontal component, the greatest magnitude of the average progress, obtained in our study by frontofacial in monobloc osteotomy. With these results, we found that the orbital volumes were completely restored, and consequently, their eye symptoms related to exorbitism were resolved. Thus, the protection of the eyeball was obtained with the technique used for both groups when compared with normal values of the orbital volumes, demonstrating the effectiveness of the surgical procedure. During this study, interesting results were found related to craniofacial linear advances, which served as the basis for the correlation with the variation of orbital volumes in each group of patients in order to evaluate the results and determine surgical parameters to gradual bone stretching with use of distractor devices. We observed in our study, group LF, an increase of 1 mm resulting in the advancement of the midface; the increase in orbital volume was 0.488 mm3 to right orbit and 0.576 mm3 to left orbit. As for group MB, for this relationship of proportionality we showed that, for an increase of 1 mm resulting in the advancement of the midface, the increase in orbital volume was 0.707 mm3 to right orbit and 0.731 mm3 to left orbit. TABLE 2. Normal Changes in Orbital Volume (Bentley et al15,16) Factor Left orbit Mean volume (cm3) Boys Girls P Right orbit Mean volume (cm3) Boys Girls P
FIGURE 10. Facial advancements—Rhinoceros software. Overview of the superposition of the sagittal (black with red outline), axial (black with green outline), and coronal (blue) planes, using the Rhinoceros software.
0–5 y
5–10 y
10–15 y
17.05 14.51 0.10
22.70 21.88 0.75
27.62 25.43 0.29
18.18 14.45 0.04
23,58 22.65 0.65
28.34 26.02 0.31
Comparison of left and right orbital volumes in boys and girls.
Probability values were determined using a t test.
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2015 Mutaz B. Habal, MD
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FIGURE 12. Average volume variation in group LF and group MB. Above, Right orbit. Below, Left orbit.
Knowing that with the advance of the midface is obtained proportional to the increase in orbital volume in the above values, we can better evaluate patients in the preoperative period and thus better define the surgical planning, having an estimate of how much we shall proceed to the face with the use of distractor devices to obtain increase in the orbital volume compatible with indexes of normality. In the postoperative period, these parameters can also help us in situations that eventual surgical complications and/or
Frontofacial Advancement Orbital Volume
FIGURE 14. Comparing the volume obtained postoperatively in relation to Bentley et al.15,16 Above, Right orbit. Below, Left orbit.
exuberant edema in the postoperative period may hinder the clinical evaluation of the surgeon in determining the exact time of completion of the distractor activation period, helping prevent unwanted results, residual exorbitism, or postoperative enophthalmos, coming to characterize failure of treatment. Therefore, in order to establish a protocol for the advancement of the midface and determine the exact moment for the completion of the activation period, we infer that the gradual bone elongation with the use of distractor devices should be terminated when the normalization of the orbit volume occurs, for both group LF and group MB; however, group LF found that it is necessary to have small variations in orbital volume, whereas large variations (70%– 80%) in group MB are necessary for obtaining a normal volume.
CONCLUSIONS (a) There was significant increase in the orbital cavity for both group LF and group MB. The average variation of the orbital volume to reach indexes of normality was higher in group MB. (b) In the quantitative and vectorial evaluation of the craniofacial movements, the magnitude of the vertical component was greater in
FIGURE 13. Comparing the volume obtained preoperatively regarding Bentley et al.15,16 Above, Right orbit. Below, Left orbit.
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2015 Mutaz B. Habal, MD
FIGURE 15. Average horizontal advancement, in group LF and group MB, for the right and left orbits.
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FIGURE 16. Average vertical advancement, in group LF and group MB, for the right and left orbits.
FIGURE 17. Correlation of orbital volume variation and resulting advance orbits, right (A ¼ LF and B ¼ MB).
FIGURE 18. Correlation of orbital volume variation and resulting advance orbits, left (A ¼ LF and B ¼ MB).
group LF, whereas the magnitude of the horizontal component was greater in group MB. (c) The correlation between craniofacial advancements and the variation of orbital volumes showed proportional greater increase in group MB. (d) The surgical procedure was effective to both group LF as for group MB, because normalization of the orbit volume when compared with the index of normality was found.
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2. Cruz AAV, Akaishi PMS, Arnaud E, et al. Exorbitism correction of faciocraniosynostoses by monobloc frontofacial advancement with distraction osteogenesis. J Craniofac Surg 2007;18:355–360 3. Meling TR, Due-Tonnessen BJ, Hogevold HE, et al. Monobloc distraction osteogenesis in pediatric patients with severe syndromal craniosynostosis. J Craniofac Surg 2004;15:990–1000 4. Bender CA, Veneman W, Veenland JF, et al. Orbital aspects following monobloc advancement in syndromic craniosynostosis. J Craniomaxillofac Surg 2013;41:e146–e153 5. Oliveira NAJ. Estudo molecular das craniossinostoses sindroˆmicas: Crouzon, Pfeiffer e Saethre-Chotzen. Dissertac¸a˜o para a otenc¸a˜o do Tı´tulo de Mestre em Cieˆncias, apresentada ao Instituto de Biocieˆncias da Universidade de Sa˜o Paulo, na A´rea de Biologia/ Gene´tica 2006 6. Nout E, van Bezooijen JS, Koudstaal MJ, et al. Orbital change following Le Fort III advancement in syndromic craniosynostosis: quantitative evaluation of orbital volume, infra-orbital rim and globe position. J Craniomaxillofac Surg 2012;40:223–228 7. Alonso N, Matushita H, Goldenberg DC, et al. Idade e indicac¸o˜es de osteotomias para avanc¸o frontofacial em pacientes com craniossinostoses sindroˆmicas. Rev Bras Cir Plast 2012;27: 223–226 8. Alonso N, Munhoz AM, Fogac¸a W, et al. Midfacial advancement by bone distraction for treatment of craniofacial deformities. J Craniofac Surg 1998;9:114–118 discussion 119–122 9. Shetye PR, Kapadia H, Grayson BH, et al. A 10-year study of skeletal stability and growth of the midface following Le Fort III advancement in syndromic craniosynostosis. Plast Reconstr Surg 2010;126:973–981 10. Swennen G, Dempf R, Schliephake H. Cranio-facial distractioosteogenesis: a review of the literature. Part II: experimental studies. Int J Oral Maxillofac Surg 2002;31:123–135 11. Swennen G, Schliephake H, Dempf R, et al. Craniofacial distraction osteogenesis: a review of the literature. Part 1: clinical studies. Int J Oral Maxillofac Surg 2001;30:89–103 12. Satoh K, Mitsukawa N, Hosaka Y. Dual midfacial distraction osteogenesis: Le Fort III minus I and Le Fort I for syndromic craniosynostosis. Plast Reconstr Surg 2003;111:1019–1028 13. Witherow H, Dunaway D, Evans R, et al. Functional outcomes in monobloc advancement by distraction using the rigid external distractor device. Plast Reconstr Surg 2008;121:1311–1322 14. Lima DSC, Alonso N, Caˆmara PRP, et al. Evaluation of cephalometric points in midface bone lengthening with the use of a rigid external device in syndromic craniosynostosis patients. Braz J Otorhinolaryngol 2009;75:395–406 15. Bentley RP, Sgouros S, Natarajan K, et al. Normal changes in orbital volume during childhood. J Neurosurg 2002;96:742–746 16. Bentley RP, Sgouros S, Natarajan K, et al. Changes in orbital volume during childhood in cases of craniosynostosis. J Neurosurg 2002;96:746–747 17. Imai K, Fujimoto T, Takahashi M, et al. Preoperative and Postoperative Orbital Volume in Patients With Crouzon and Apert syndrome. J Craniofac Surg 2013;24:191–194 18. Festa F, Pagnoni M, Valerio R, et al. Orbital volume and surface after Le Fort III advancement in syndromic craniosynostosis. J Craniofac Surg 2012;23:789–792 19. Forbes G, Gehring DG, Gorman CA, et al. Volume measurements of normal orbital structures by computed tomographic analysis. AJR Am J Roentgenol 1985;145:149–154
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