- Email: [email protected]
Three-dimensional position changes of the midface following Le Fort III advancement in syndromic craniosynostosis
Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 820e824
Contents lists available at ScienceDirect
Journal of Cranio-Maxillo-Facial Surgery journal homepage: www.jcmfs.com
Three-dimensional position changes of the midface following Le Fort III advancement in syndromic craniosynostosis Frederik P. Bouw a, *, Erik Nout a, b, e, Jine S. van Bezooijen a, Maarten J. Koudstaal a, Jifke F. Veenland c, d, Eppo B. Wolvius a a
Department of Oral and Maxillofacial Surgery, Erasmus MC University Medical Center Rotterdam, The Netherlands Department of Oral and Maxillofacial Surgery, St Elisabeth Hospital Tilburg, The Netherlands Department of Medical Informatics, Faculty of Medicine, Erasmus MC University Medical Center Rotterdam, The Netherlands d Department of Radiology, Erasmus MC University Medical Center Rotterdam, The Netherlands e Department of Oral and Maxillofacial Surgery, University Hospital Brussels, Belgium b c
a r t i c l e i n f o
a b s t r a c t
Article history: Paper received 30 September 2014 Accepted 2 April 2015 Available online 29 April 2015
Little is known about the positional change of the Le Fort III segment following advancement. To study this, pre- and postoperative computed tomography scans of 18 craniosynosthosis patients were analyzed. The Le Fort III segment movement was measured by creating a reference coordinate system and by superpositioning the postoperative over the preoperative scan. On both the pre- and postoperative scans, four anatomical landmarks were marked: the most anterior point of the left and right foramen infraorbitale, the nasion, and the anterior nasal spine. A significant anterior movement of the four reference points was observed. No significant transversal differences were found. A significant difference between the anterior movement of the nasion and anterior nasal spine was found. In vertical dimension, there was a significant cranial movement of nasion in the study group. In addition, from all patients standardized lateral X-rays were viewed to determine the location and direction of force application that were linked to the outcomes of the three-dimensional movement of the nasion and anterior nasal spine (ANS) and the surgical technique. Conclusively, a significant advancement of the midface can be achieved with Le Fort III distraction osteogenesis in this specific patient group. Counterclockwise movement seemed to be the most dominant movement despite different modes of anchorage. © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
Keywords: Le Fort III Distraction osteogenesis Syndromic craniosynosthosis Positional changes Three-dimensional
1. Introduction Due to premature fusion of the calvarial sutures, patients with syndromic craniosynosthosis (SCS) often suffer from severe underdevelopment of the midface. The Le Fort (LF) III advancement is frequently performed to correct associated problems such as obstructive sleep apnea (OSA), severe exorbitism, distorted facial appearance, and class III malocclusion. The conventional LF III osteotomy constitutes a one-step technique in which the midfacial segment is osteotomized, advanced, and fixed in the desired position. Due to the substantial advancement of the midface including some degree of overcorrection, interposition of bone grafts is often
* Corresponding author. Erasmus Medical Center, Department of Oral and Maxillofacial Surgery, Room D-230, Dr Molewaterplein 40, 3000 CA, Rotterdam, The Netherlands. Tel.: þ31 10 703 39 55; fax: þ31 10 463 30 98. E-mail address: [email protected] (F.P. Bouw).
necessary to ensure postsurgical stability and to reduce relapse. However, bone grafting is associated with donor-site morbidity. Several authors have reported substantial (pseudo-) relapse following conventional LF III advancement due to continuing growth of the mandible together with absence of maxillary growth (Bachmayer et al., 1986; Kaban et al., 1986; McCarthy et al., 1990). Advancement using this technique is limited, and nowadays many surgeons use distraction osteogenesis (DO) in case a considerable advancement of the midface is indicated. With LF III DO, less relapse and less co-morbidity is reported (Fearon, 2005). Other advantages are the stimulation of histogenesis with gradual distraction and the adjustment of vectors of force during the activation period of DO in case of extraoral distraction devices. Using LF III DO with extraoral distractors requires fixation of the LF III segment to the distractor. Dental anchorage via an oral splint combined with paranasal and/or zygomatic bony anchorage is frequently used. Ideally, an anterior translation of the LF III segment should occur to correct the midface hypoplasia. Unfortunately,
http://dx.doi.org/10.1016/j.jcms.2015.04.003 1010-5182/© 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
F.P. Bouw et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 820e824
various authors report a counterclockwise rotation of the LF III segment, which can cause an anterior open bite and which reduces the advancement of the orbitozygomatico complex (Denny et al., 2003; Fearon, 2005; Nout et al., 2008; Shetye et al., 2009). Additional orthognathic surgery is frequently indicated to correct the anterior open bite (Nout et al., 2011). Little is known about the positional change of the LF III segment following advancement. n et al. described a controlled advancement of the LF However Rolda III segment in 1 SCS patient (Rold an et al., 2011). Shetye et al. described the importance of the location and direction of force application and the change of position of the LF III segment in a cephalometric study with 18 SCS patients (Shetye et al., 2009). In the present study, the change in position of the LF III segment, based on analysis of three-dimensional (3D) movements of the LF III segment using pre- and postoperative computed tomography (CT) data of patients with SCS, is reported. In this way, we hope to gain more insight into the complex directional changes observed in the midface postoperatively and to predict end-position more accurately. 2. Material and methods 2.1. Study patients All SCS patients who underwent LF III osteotomy in the Erasmus University Medical Center between 2003 and 2009 were evaluated. Patients were included when a pre- and postoperative CT scan and lateral X-rays were available for analysis. 2.2. CT scans All CT scans were made in a supine position using the same scanner (Emotion 6, Siemens, Munich, Germany) and had a slice thickness of 1.25 mm. Sedation was used when indicated. 2.3. Surgical procedure All patients were orally intubated. Using a coronal approach, the frontotemporal skull, lateral orbital region, nasal region, zygomatic arch and body were exposed. Osteotomies, following the LF IIIeTessier III design, were made through the frontozygomatic suture, floor of the orbit, and the nasal bone, using a reciprocating saw and osteotomes. A cephalo-osteotome was used to separate the vomer and ethmoid from the cranial base in the midline. The pterygomaxillary junction was separated either from the coronal approach or through a gingivobuccal access. Rowe's forceps were used to mobilize the LF III segment. In the case of a conventional LF III osteotomy, the midface segment is advanced as much as needed, and fixated using osteosynthesis plates and screws. In case of LF III DO, the internal (Marchac devices, Martin Medizin, Tuttlingen, Germany) or external distractors (RED device, Martin Medizin, Tuttlingen, Germany or External Midface Distractor, Synthes, Zurich, Switzerland) were positioned and fixed to the LF III segment after closing of the wounds. 2.4. LF III distraction protocol All patients were hospitalized for 7 days regardless of age. The first 24 h after the surgery, the patients were admitted to the intensive care unit. DO was initiated after 1 week. The rate of distraction was 1 mm (mm) per day in two daily activations. The duration of DO depended on the desired advancement. During the distraction period, vector modifications took place when necessary. A consolidation period of 3 months was observed.
821
2.5. Data analysis 2.5.1. LF III segment movement The software program MevisLab Version 2.0 (Mevis Medical Solutions AG, Bremen) was used to import and analyze the CT scans by means of a custom-designed tool (Nout et al., 2012). Similar to the method that our group previously described, a coordinate system was created that allowed us to quantify the movement of structures independent of the position of the patient in the CT scan (Fig. 1). In this way, the movement of the LF III segment could be analyzed in three dimensions. Skeletal landmarks were identified to compare the movement of LF III segment pre- and posttreatment: the most anterior point of the left and right foramen infraorbitale, the nasion (N), and the anterior nasal spine (ANS). 2.5.2. Mode of anchorage From all patients, standardized lateral X-rays were viewed to determine the location and direction of force application that were linked to the outcomes of the 3D movement of N and ANS and the surgical technique (Fig. 2). An arbitrary cut-off point of 2.5-mm difference was chosen to categorize the type of movement of the LF III segment. In case of a difference between N and ANS of 2.5 to 2.5 mm, the movement of the LF III segment was classified as a translation. When the difference between N and ANS was more than 2.5 mm, the movement was considered a clockwise movement; an outcome more than 2.5 mm was considered a counterclockwise movement. 2.5.3. Statistical analysis SPSS for Windows XP Version 15.0 (SPSS Inc., Chicago, IL, USA) was used to analyze all data. To outline the interobserver variability, a second observer performed all measurements in five randomly selected patients of the study group, independent of the first person. With the intraclass correlation coefficient (ICC), the interobserver reliability was calculated. The pre- and postoperative CT data were analyzed by means of the paired sample t-test. A p-value of less than 0.05 (two-tailed) was considered to be statistically significant. 3. Results 3.1. Reliability The interobserver agreements with respect to the LF III segment 3D measurements were evident; the ICC ranged from 0.86 to 0.99. 3.2. Patients Of a total of 27 patients with LF III advancement operation between 2003 and 2009, nine patients were excluded because of insufficient data. Eighteen SCS patients were included (nine female and nine male) with Crouzon (four female and five male), Apert (five female and two male), and Pfeiffer syndrome (two male). The indications for LF III advancement in this study group were pressing OSA, as confirmed with polysomnography (four patients) and symptomatic exorbitism (four patients). Ten patients underwent operation because of a relative indication. All patients had severe midfacial hypoplasia and associated class III malocclusion. Seventeen patients underwent LF III DO with external (15 patients) or internal (two patients) devices. One patient underwent a conventional LF III osteotomy. The average age at time of LF III advancement was 14.7 years (standard deviation [SD] 4.7 years). The average time interval between LF III advancement and the preoperative CT scan was 7.8 months (SD 7.7 months). Postoperatively, this time interval was 7.2 months (SD 4.6 months).
822
F.P. Bouw et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 820e824
Fig. 1. Horizontal plane depicted in red, created by means of the three reference points; using the most lateral points of the left and right lateral semicircular canal (LSCC) and the most anterior point of the right LSCC.
Fig. 2. Example of a combined dental/paranasal fixation (left) and combined paranasal/zygomatic fixation (right).
3.3. LF III segment movement
3.4. Clinical outcomes
In Table 1 the movement of the four points of LF III segment are presented. The LF III segment showed a significant anterior movement of the left foramen infraorbitale (mean 12.2 mm, SD 4.1), right foramen infraorbitale (mean 12.8 mm, SD 5.3), N (mean 5.6 mm, SD 2.9), and ANS (mean 12.6 mm, SD 5.1) (for all four reference points, p < 0.001). There was no significant difference between the right and the left infraorbital foramen (p > 0.707 in all three dimensions). There was a significant difference between the anterior movement of the N and ANS (p < 0.001) and a significant cranial movement of the N (p ¼ 0.014). The ANS showed more anterior movement compared to the N, which resulted in an overall counterclockwise movement of the LF III segment.
The LF III DO procedure was shown to effectively advance the infraorbital rim in all patients, which was clinically reflected as a normalization of the exorbitism. With regard to the OSA, the results were less obvious. These results were published in two separate articles from our group (Nout et al., 2012). Because of the development of an anterior open bite during DO, a malocclusion was observed in most patients (Fig. 3). Table 2 presents the difference in anterior movement between N and ANS and the resulting vector. In 13 patients, a counterclockwise movement was observed, and in one patient a clockwise movement was apparent. In the other four patients, a pure anterior translation was observed. In the counterclockwise group, all patients
Table 1 Le Fort III segment movement in the study group.
Left foramen Right foramen Nasion ANS
Mean SD Mean SD Mean SD Mean SD
Anterior movement (mm)
Vertical movement (mm)
Lateral movement (mm)
12.2 4.1* 12.8 5.3* 5.6 2.9* 12.6 5.1*
0.5 4.4 0.4 4.1 2.9 4.4* 1.0 5.8
0.9 3.2 0.0 3.0 0.1 2.7 1.5 2.8
Significant (p < 0.05) movements are marked with an asterisk (*).
F.P. Bouw et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 820e824
Fig. 3. A patient with an open bite resulting from a counter clockwise (CCW) rotation of the LF III segment.
underwent LF III DO with external distractors. One patient with a clockwise movement underwent LF III DO with an internal distractor. In the translation group, two patients underwent LF III DO with an external distractor. One patient underwent a LF III DO osteotomy with an internal distractor, and in one patient a conventional LF III osteotomy was performed. With both bony (paranasal) and dental fixation of the external distractor, 10 patients showed a counterclockwise movement and two patients showed translation of the LF III segment. All three patients with the fixation located both paranasally and at the level of the zygoma showed counterclockwise movement. In the two patients with internal distractor devices, anterior translation and clockwise rotation was found, and in the patient with a conventional LF III osteotomy, anterior translation of the LF III segment was observed. 4. Discussion The purpose of LF III advancement is to correct midface hypoplasia that could lead to OSA, exorbitism, distorted facial appearance, and class III malocclusion. In most patients, a linear antero-caudal translation of the LF III segment should be achieved. However, in a significant number of cases, counterclockwise movement is
823
observed, which can lead to an unfavorable anterior open bite. Shetye et al. have performed a retrospective study in 18 patients with LF external DO to determine the response of the bony LF III segment to variations in vector location and direction (Shetye et al., 2009). In relation to the location and direction of force application, four different movements were observed: anterior translation, clockwise movement, counterclockwise movement, and anterocaudal translation. In this study, we observed counterclockwise movement, clockwise movement, and anterior translation of the LF III segment. The center of resistance is the key element to controlling the n et al. demonstrated movement of an object (Nanda, 1978). Rolda that the skeletal fixation on the level of the nasion produced the desired clockwise rotation. In their case, a three-point skeletal fixation with traction onto the nasal dorsum allowed a controlled n et al., 2011). Figueroa central advancement of the midface (Rolda et al. showed, in an in vitro study, that the center of resistance of the LF III segment is situated at a point nearby the ANS (in the frontal view) and close to the anterior base of the maxillary buttress/ anterior maxillary-malar suture (in the sagittal view) (Figueroa et al., 2010). Although analysis of cephalograms showed that force after LF III advancement was applied close to this center of resistance, Figueroa et al. observed a counterclockwise movement in more than half of their patients. To prevent this movement, Figueroa et al. recommended an action of forces both above and below the center of mass to control the vector of force and to create rotational control. Shetye et al. analyzed the effects of different force directions on the movement of the LF III segment. They also found that counterclockwise rotation is the most common movement in patients after LF III advancement. Hypothetically, it is possible that the vector of force application was still oriented too far cranially in these patients. Another explanation could be that the location of the center of resistance in patients has no fixed location and differs considerably between patients. Although plausible, we think that another factor is responsible for the counterclockwise rotation. Similar to the findings of these two aforementioned studies, we also showed that counterclockwise rotation of the LF III segment was the dominant movement. Hypothetically we think that there is a difference in soft tissue resistance between the upper part of the midface and the lower part of the midface. Soft tissue resistance might be more difficult to overcome on the cranial side of the LF III segment when compared to the soft tissue resistance on the caudal site of the LF III segment. Possibly because of the high soft tissue resistance on the cranial side of the LF III segment, there
Table 2 Differences in anterior movements of the segments anterior nasal spine (ANS) and nasion compared to the location of force application. Patient no.
Anterior movement N (mm)
Anterior movement ANS (mm)
Nasion minus ANS (mm)
Segmental movement
Location of force application
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
9.3 8.4 5.4 8.7 0.4 2.1 4.1 6.0 0.7 7.2 7.6 4.2 5.7 7.6 4.4 1.6 7.8 9.1
11.1 13.0 14.2 6.9 13.8 11.6 7.6 5.1 18.1 14.6 16.4 16.2 16.2 16.3 3.6 21.8 4.7 15.9
1.8 4.6 8.8 1.8 13.4 9.5 3.5 0.9 17.4 7.4 8.8 12.0 10.5 8.7 0.8 20.2 3.1 6.8
T CCW CCW T CCW CCW CCW T CCW CCW CCW CCW CCW CCW T CCW CW CCW
PD PD PD INT PD PD PD PD PD PD PZ PD PD PZ d PZ INT PD
CCW, counterclockwise; CW, clockwise; D, dental; INT, internal distraction; P, paranasal; T, translation; Z, zygoma. Patient 15 underwent a conventional Le Fort III osteotomy.
824
F.P. Bouw et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 820e824
is a natural preference for counterclockwise movement, and distraction forces after LF III osteotomies should be oriented extremely caudally to prevent a counterclockwise rotation. In cases in which counterclockwise rotation occurred, an anterior open bite is often observed after the distraction period. To correct this anterior open bite, additional orthognathic surgery may be indicated. In a recently published article from our group, we showed that, on one hand, satisfactory results can be obtained after additional surgery (Nout et al., 2011). On the other hand, however, many patients with a postoperative malocclusion did not receive additional orthognathic surgery because of patient factors of which syndromicrelated mental retardation is the most important. Coping abilities and compliance in these patients is severely diminished. The protocol of the craniofacial team is as follows: in urgent need, for example, in case of severe obstructive sleep apnea or symptomatic exorbitism, age plays no role, and distraction is planned whenever needed. In case of a relative indication (malocclusion, aesthetics/ psychosocial concerns), the distraction is carried out between 8 and 12 years, or at the age of 18 years or more when skeletal maturity has been reached. The distraction is preferably not performed between 12 and 18 years, mainly because of puberty. In the case of additional orthognatic surgery, we prefer surgery after skeletal maturity has been reached. Unfortunately, most of the patients with an indication for additional surgery did not undergo this operation because of the lack of functional complaints or patient factors. Nowadays, more and more studies analyze the movement of the LF III segment in three dimensions. In contrast to other studies that used two-dimensional (2D) methods (Fearon, 2005; Meazzini et al., 2005), a 3D analysis has no interference with overlapping bony structures. Landmarks can be more accurately identified, which makes 3D analysis superior to a 2D analysis (Chien et al., 2009). The interobserver reliability was shown to be very good, which makes the reported method using the software program MevisLab reproducible. On the other hand, this method is laborious. Mathematical analysis of the length of the vector between both infraorbital foramens showed no significant different of the length of the vector pre- and postoperatively. Deformation of the LF III segment is unlikely in the study group. It seems that 2D analysis might be sufficient to predict segmental movements. In the past, fixation after LF III DO was achieved by means of wire attachment to the intraoral dental splint. Besides skeletal movement, dental movements including periodontal tissue loss with front teeth at risk were also observed. To exclude these dental problems and to enhance vector control, bony anchorage increasingly was used in craniofacial surgery. In this study, we showed that despite the combination of skeletal and dental anchorage of the fixation threads, unwanted counterclockwise movements still occur. Recent articles have shown that by using more rigid anchorage, improved vector control is possible even when solely dental anchorage is applied (Shetye et al., 2010; Lim et al., 2012). Fearon et al. demonstrated a more rigid anchorage between the dental splint with an additional midline superior point of traction n et al. reported at the base of the nasal bone (Fearon, 2005). Rolda better directional control of the segment by using self-cutting n screws through the nasal bone and piriform aperture (Rolda et al., 2011). According to Shetye et al., more rigid anchorage between the bar and the dental and/or skeletal anchorage points is preferable (Shetye et al., 2010). In taking into account literature findings with our data, it seems that more rigid anchorage as well as knowledge and understanding of the center of mass and other variables such as age, gender, previous surgery, etc. is necessary. Together these factors will improve prediction of the outcome of LF III DO and perhaps will reduce the number of additional orthognathic surgeries necessary because of unfavorable movement of the LF III segment.
5. Conclusion With LF III DO, a significant advancement is achievable, although the control of the vector of force was difficult in our study group and led to unwanted counterclockwise movements in a significant number of cases. By analyzing the movement of the LF III segment in three dimensions and relating it to the mode of fixation, no firm conclusions can be drawn about the ideal location and the number of anchorage points. Rigid fixation between the dental or skeletal fixation points and the external frame seems necessary and may lead to a more predictable result. Moreover, variables such as soft tissue envelope, age, mode of anchorage, and center of mass should be included in the design of force movement.
Sources of support No sources of support have been used.
Financial interest None of the authors has a financial interest in this study.
Competing interests None declared.
References Bachmayer DI, Ross RB, Munro IR: Maxillary growth following LeFort III advancement surgery in Crouzon, Apert, and Pfeiffer syndromes. Am J Orthod Dentofacial Orthop 90: 420e430, 1986 Chien PC, Parks ET, Eraso F, Hartsfield JK, Roberts WE, Ofner S: Comparison of reliability in anatomical landmark identification using two-dimensional digital cephalometrics and three-dimensional cone beam computed tomography in vivo. Dentomaxillofac Radiol 38: 262e273, 2009 Denny AD, Kalantarian B, Hanson PR: Rotation advancement of the midface by distraction osteogenesis. Plast Reconstr Surg 111: 1789e1799, 2003 discussion 1800 1803 Fearon JA: Halo distraction of the Le Fort III in syndromic craniosynostosis: a longterm assessment. Plast Reconstr Surg 115: 1524e1536, 2005 Figueroa AA, Polley JW, Figueroa AD: Biomechanical considerations for distraction of the monobloc, Le Fort III, and Le Fort I segments. Plast Reconstr Surg 126: 1005e1013, 2010 Kaban LB, Conover M, Mulliken JB: Midface position after Le Fort III advancement: a long-term follow-up study. Cleft Palate J 23(Suppl. 1): 75e77, 1986 Lim H, Ko EW, Lo LJ: Le Fort III distraction osteogenesis: modification of the intraoral splint in the rigid external distraction. J Craniofac Surg 23: 856e858, 2012 McCarthy JG, La Trenta GS, Breitbart AS, Grayson BH, Bookstein FL: The Le Fort III advancement osteotomy in the child under 7 years of age. Plast Reconstr Surg 86: 633e646, 1990 discussion 647 649 Meazzini MC, Mazzoleni F, Caronni E, Bozzetti A: Le Fort III advancement osteotomy in the growing child affected by Crouzon's and Apert's syndromes: presurgical and postsurgical growth. J Craniofac Surg 16: 369e377, 2005 Nanda R: Protraction of maxilla in rhesus monkeys by controlled extraoral forces. Am J Orthod 74: 121e141, 1978 Nout E, Cesteleyn LL, van der Wal KG, van Adrichem LN, Mathijssen IM, Wolvius EB: Advancement of the midface, from conventional Le Fort III osteotomy to Le Fort III distraction: review of the literature. Int J Oral Maxillofac Surg 37: 781e789, 2008 Nout E, Koudstaal MJ, Wolvius EB, Van der Wal KG: Additional orthognathic surgery following Le Fort III and monobloc advancement. Int J Oral Maxillofac Surg 40: 679e684, 2011 Nout E, van Bezooijen JS, Koudstaal MJ, Veenland JF, Hop WC, Wolvius EB, 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 40: 223e228, 2012 n JC, Moralis A, Dendorfer S, Witte J, Reicheneder C: Controlled central Rolda advancement of the midface after Le Fort III osteotomy by a 3-point skeletal anchorage. J Craniofac Surg 22: 2384e2386, 2011 Shetye PR, Giannoutsos E, Grayson BH, McCarthy JG: Le Fort III distraction: part I. Controlling position and vectors of the midface segment. Plast Reconstr Surg 124: 871e878, 2009 Shetye PR, Grayson BH, McCarthy JG: Le Fort III distraction: controlling position and path of the osteotomized midface segment on a rigid platform. J Craniofac Surg 21: 1118e1121, 2010
Contents lists available at ScienceDirect
Journal of Cranio-Maxillo-Facial Surgery journal homepage: www.jcmfs.com
Three-dimensional position changes of the midface following Le Fort III advancement in syndromic craniosynostosis Frederik P. Bouw a, *, Erik Nout a, b, e, Jine S. van Bezooijen a, Maarten J. Koudstaal a, Jifke F. Veenland c, d, Eppo B. Wolvius a a
Department of Oral and Maxillofacial Surgery, Erasmus MC University Medical Center Rotterdam, The Netherlands Department of Oral and Maxillofacial Surgery, St Elisabeth Hospital Tilburg, The Netherlands Department of Medical Informatics, Faculty of Medicine, Erasmus MC University Medical Center Rotterdam, The Netherlands d Department of Radiology, Erasmus MC University Medical Center Rotterdam, The Netherlands e Department of Oral and Maxillofacial Surgery, University Hospital Brussels, Belgium b c
a r t i c l e i n f o
a b s t r a c t
Article history: Paper received 30 September 2014 Accepted 2 April 2015 Available online 29 April 2015
Little is known about the positional change of the Le Fort III segment following advancement. To study this, pre- and postoperative computed tomography scans of 18 craniosynosthosis patients were analyzed. The Le Fort III segment movement was measured by creating a reference coordinate system and by superpositioning the postoperative over the preoperative scan. On both the pre- and postoperative scans, four anatomical landmarks were marked: the most anterior point of the left and right foramen infraorbitale, the nasion, and the anterior nasal spine. A significant anterior movement of the four reference points was observed. No significant transversal differences were found. A significant difference between the anterior movement of the nasion and anterior nasal spine was found. In vertical dimension, there was a significant cranial movement of nasion in the study group. In addition, from all patients standardized lateral X-rays were viewed to determine the location and direction of force application that were linked to the outcomes of the three-dimensional movement of the nasion and anterior nasal spine (ANS) and the surgical technique. Conclusively, a significant advancement of the midface can be achieved with Le Fort III distraction osteogenesis in this specific patient group. Counterclockwise movement seemed to be the most dominant movement despite different modes of anchorage. © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
Keywords: Le Fort III Distraction osteogenesis Syndromic craniosynosthosis Positional changes Three-dimensional
1. Introduction Due to premature fusion of the calvarial sutures, patients with syndromic craniosynosthosis (SCS) often suffer from severe underdevelopment of the midface. The Le Fort (LF) III advancement is frequently performed to correct associated problems such as obstructive sleep apnea (OSA), severe exorbitism, distorted facial appearance, and class III malocclusion. The conventional LF III osteotomy constitutes a one-step technique in which the midfacial segment is osteotomized, advanced, and fixed in the desired position. Due to the substantial advancement of the midface including some degree of overcorrection, interposition of bone grafts is often
* Corresponding author. Erasmus Medical Center, Department of Oral and Maxillofacial Surgery, Room D-230, Dr Molewaterplein 40, 3000 CA, Rotterdam, The Netherlands. Tel.: þ31 10 703 39 55; fax: þ31 10 463 30 98. E-mail address: [email protected] (F.P. Bouw).
necessary to ensure postsurgical stability and to reduce relapse. However, bone grafting is associated with donor-site morbidity. Several authors have reported substantial (pseudo-) relapse following conventional LF III advancement due to continuing growth of the mandible together with absence of maxillary growth (Bachmayer et al., 1986; Kaban et al., 1986; McCarthy et al., 1990). Advancement using this technique is limited, and nowadays many surgeons use distraction osteogenesis (DO) in case a considerable advancement of the midface is indicated. With LF III DO, less relapse and less co-morbidity is reported (Fearon, 2005). Other advantages are the stimulation of histogenesis with gradual distraction and the adjustment of vectors of force during the activation period of DO in case of extraoral distraction devices. Using LF III DO with extraoral distractors requires fixation of the LF III segment to the distractor. Dental anchorage via an oral splint combined with paranasal and/or zygomatic bony anchorage is frequently used. Ideally, an anterior translation of the LF III segment should occur to correct the midface hypoplasia. Unfortunately,
http://dx.doi.org/10.1016/j.jcms.2015.04.003 1010-5182/© 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
F.P. Bouw et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 820e824
various authors report a counterclockwise rotation of the LF III segment, which can cause an anterior open bite and which reduces the advancement of the orbitozygomatico complex (Denny et al., 2003; Fearon, 2005; Nout et al., 2008; Shetye et al., 2009). Additional orthognathic surgery is frequently indicated to correct the anterior open bite (Nout et al., 2011). Little is known about the positional change of the LF III segment following advancement. n et al. described a controlled advancement of the LF However Rolda III segment in 1 SCS patient (Rold an et al., 2011). Shetye et al. described the importance of the location and direction of force application and the change of position of the LF III segment in a cephalometric study with 18 SCS patients (Shetye et al., 2009). In the present study, the change in position of the LF III segment, based on analysis of three-dimensional (3D) movements of the LF III segment using pre- and postoperative computed tomography (CT) data of patients with SCS, is reported. In this way, we hope to gain more insight into the complex directional changes observed in the midface postoperatively and to predict end-position more accurately. 2. Material and methods 2.1. Study patients All SCS patients who underwent LF III osteotomy in the Erasmus University Medical Center between 2003 and 2009 were evaluated. Patients were included when a pre- and postoperative CT scan and lateral X-rays were available for analysis. 2.2. CT scans All CT scans were made in a supine position using the same scanner (Emotion 6, Siemens, Munich, Germany) and had a slice thickness of 1.25 mm. Sedation was used when indicated. 2.3. Surgical procedure All patients were orally intubated. Using a coronal approach, the frontotemporal skull, lateral orbital region, nasal region, zygomatic arch and body were exposed. Osteotomies, following the LF IIIeTessier III design, were made through the frontozygomatic suture, floor of the orbit, and the nasal bone, using a reciprocating saw and osteotomes. A cephalo-osteotome was used to separate the vomer and ethmoid from the cranial base in the midline. The pterygomaxillary junction was separated either from the coronal approach or through a gingivobuccal access. Rowe's forceps were used to mobilize the LF III segment. In the case of a conventional LF III osteotomy, the midface segment is advanced as much as needed, and fixated using osteosynthesis plates and screws. In case of LF III DO, the internal (Marchac devices, Martin Medizin, Tuttlingen, Germany) or external distractors (RED device, Martin Medizin, Tuttlingen, Germany or External Midface Distractor, Synthes, Zurich, Switzerland) were positioned and fixed to the LF III segment after closing of the wounds. 2.4. LF III distraction protocol All patients were hospitalized for 7 days regardless of age. The first 24 h after the surgery, the patients were admitted to the intensive care unit. DO was initiated after 1 week. The rate of distraction was 1 mm (mm) per day in two daily activations. The duration of DO depended on the desired advancement. During the distraction period, vector modifications took place when necessary. A consolidation period of 3 months was observed.
821
2.5. Data analysis 2.5.1. LF III segment movement The software program MevisLab Version 2.0 (Mevis Medical Solutions AG, Bremen) was used to import and analyze the CT scans by means of a custom-designed tool (Nout et al., 2012). Similar to the method that our group previously described, a coordinate system was created that allowed us to quantify the movement of structures independent of the position of the patient in the CT scan (Fig. 1). In this way, the movement of the LF III segment could be analyzed in three dimensions. Skeletal landmarks were identified to compare the movement of LF III segment pre- and posttreatment: the most anterior point of the left and right foramen infraorbitale, the nasion (N), and the anterior nasal spine (ANS). 2.5.2. Mode of anchorage From all patients, standardized lateral X-rays were viewed to determine the location and direction of force application that were linked to the outcomes of the 3D movement of N and ANS and the surgical technique (Fig. 2). An arbitrary cut-off point of 2.5-mm difference was chosen to categorize the type of movement of the LF III segment. In case of a difference between N and ANS of 2.5 to 2.5 mm, the movement of the LF III segment was classified as a translation. When the difference between N and ANS was more than 2.5 mm, the movement was considered a clockwise movement; an outcome more than 2.5 mm was considered a counterclockwise movement. 2.5.3. Statistical analysis SPSS for Windows XP Version 15.0 (SPSS Inc., Chicago, IL, USA) was used to analyze all data. To outline the interobserver variability, a second observer performed all measurements in five randomly selected patients of the study group, independent of the first person. With the intraclass correlation coefficient (ICC), the interobserver reliability was calculated. The pre- and postoperative CT data were analyzed by means of the paired sample t-test. A p-value of less than 0.05 (two-tailed) was considered to be statistically significant. 3. Results 3.1. Reliability The interobserver agreements with respect to the LF III segment 3D measurements were evident; the ICC ranged from 0.86 to 0.99. 3.2. Patients Of a total of 27 patients with LF III advancement operation between 2003 and 2009, nine patients were excluded because of insufficient data. Eighteen SCS patients were included (nine female and nine male) with Crouzon (four female and five male), Apert (five female and two male), and Pfeiffer syndrome (two male). The indications for LF III advancement in this study group were pressing OSA, as confirmed with polysomnography (four patients) and symptomatic exorbitism (four patients). Ten patients underwent operation because of a relative indication. All patients had severe midfacial hypoplasia and associated class III malocclusion. Seventeen patients underwent LF III DO with external (15 patients) or internal (two patients) devices. One patient underwent a conventional LF III osteotomy. The average age at time of LF III advancement was 14.7 years (standard deviation [SD] 4.7 years). The average time interval between LF III advancement and the preoperative CT scan was 7.8 months (SD 7.7 months). Postoperatively, this time interval was 7.2 months (SD 4.6 months).
822
F.P. Bouw et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 820e824
Fig. 1. Horizontal plane depicted in red, created by means of the three reference points; using the most lateral points of the left and right lateral semicircular canal (LSCC) and the most anterior point of the right LSCC.
Fig. 2. Example of a combined dental/paranasal fixation (left) and combined paranasal/zygomatic fixation (right).
3.3. LF III segment movement
3.4. Clinical outcomes
In Table 1 the movement of the four points of LF III segment are presented. The LF III segment showed a significant anterior movement of the left foramen infraorbitale (mean 12.2 mm, SD 4.1), right foramen infraorbitale (mean 12.8 mm, SD 5.3), N (mean 5.6 mm, SD 2.9), and ANS (mean 12.6 mm, SD 5.1) (for all four reference points, p < 0.001). There was no significant difference between the right and the left infraorbital foramen (p > 0.707 in all three dimensions). There was a significant difference between the anterior movement of the N and ANS (p < 0.001) and a significant cranial movement of the N (p ¼ 0.014). The ANS showed more anterior movement compared to the N, which resulted in an overall counterclockwise movement of the LF III segment.
The LF III DO procedure was shown to effectively advance the infraorbital rim in all patients, which was clinically reflected as a normalization of the exorbitism. With regard to the OSA, the results were less obvious. These results were published in two separate articles from our group (Nout et al., 2012). Because of the development of an anterior open bite during DO, a malocclusion was observed in most patients (Fig. 3). Table 2 presents the difference in anterior movement between N and ANS and the resulting vector. In 13 patients, a counterclockwise movement was observed, and in one patient a clockwise movement was apparent. In the other four patients, a pure anterior translation was observed. In the counterclockwise group, all patients
Table 1 Le Fort III segment movement in the study group.
Left foramen Right foramen Nasion ANS
Mean SD Mean SD Mean SD Mean SD
Anterior movement (mm)
Vertical movement (mm)
Lateral movement (mm)
12.2 4.1* 12.8 5.3* 5.6 2.9* 12.6 5.1*
0.5 4.4 0.4 4.1 2.9 4.4* 1.0 5.8
0.9 3.2 0.0 3.0 0.1 2.7 1.5 2.8
Significant (p < 0.05) movements are marked with an asterisk (*).
F.P. Bouw et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 820e824
Fig. 3. A patient with an open bite resulting from a counter clockwise (CCW) rotation of the LF III segment.
underwent LF III DO with external distractors. One patient with a clockwise movement underwent LF III DO with an internal distractor. In the translation group, two patients underwent LF III DO with an external distractor. One patient underwent a LF III DO osteotomy with an internal distractor, and in one patient a conventional LF III osteotomy was performed. With both bony (paranasal) and dental fixation of the external distractor, 10 patients showed a counterclockwise movement and two patients showed translation of the LF III segment. All three patients with the fixation located both paranasally and at the level of the zygoma showed counterclockwise movement. In the two patients with internal distractor devices, anterior translation and clockwise rotation was found, and in the patient with a conventional LF III osteotomy, anterior translation of the LF III segment was observed. 4. Discussion The purpose of LF III advancement is to correct midface hypoplasia that could lead to OSA, exorbitism, distorted facial appearance, and class III malocclusion. In most patients, a linear antero-caudal translation of the LF III segment should be achieved. However, in a significant number of cases, counterclockwise movement is
823
observed, which can lead to an unfavorable anterior open bite. Shetye et al. have performed a retrospective study in 18 patients with LF external DO to determine the response of the bony LF III segment to variations in vector location and direction (Shetye et al., 2009). In relation to the location and direction of force application, four different movements were observed: anterior translation, clockwise movement, counterclockwise movement, and anterocaudal translation. In this study, we observed counterclockwise movement, clockwise movement, and anterior translation of the LF III segment. The center of resistance is the key element to controlling the n et al. demonstrated movement of an object (Nanda, 1978). Rolda that the skeletal fixation on the level of the nasion produced the desired clockwise rotation. In their case, a three-point skeletal fixation with traction onto the nasal dorsum allowed a controlled n et al., 2011). Figueroa central advancement of the midface (Rolda et al. showed, in an in vitro study, that the center of resistance of the LF III segment is situated at a point nearby the ANS (in the frontal view) and close to the anterior base of the maxillary buttress/ anterior maxillary-malar suture (in the sagittal view) (Figueroa et al., 2010). Although analysis of cephalograms showed that force after LF III advancement was applied close to this center of resistance, Figueroa et al. observed a counterclockwise movement in more than half of their patients. To prevent this movement, Figueroa et al. recommended an action of forces both above and below the center of mass to control the vector of force and to create rotational control. Shetye et al. analyzed the effects of different force directions on the movement of the LF III segment. They also found that counterclockwise rotation is the most common movement in patients after LF III advancement. Hypothetically, it is possible that the vector of force application was still oriented too far cranially in these patients. Another explanation could be that the location of the center of resistance in patients has no fixed location and differs considerably between patients. Although plausible, we think that another factor is responsible for the counterclockwise rotation. Similar to the findings of these two aforementioned studies, we also showed that counterclockwise rotation of the LF III segment was the dominant movement. Hypothetically we think that there is a difference in soft tissue resistance between the upper part of the midface and the lower part of the midface. Soft tissue resistance might be more difficult to overcome on the cranial side of the LF III segment when compared to the soft tissue resistance on the caudal site of the LF III segment. Possibly because of the high soft tissue resistance on the cranial side of the LF III segment, there
Table 2 Differences in anterior movements of the segments anterior nasal spine (ANS) and nasion compared to the location of force application. Patient no.
Anterior movement N (mm)
Anterior movement ANS (mm)
Nasion minus ANS (mm)
Segmental movement
Location of force application
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
9.3 8.4 5.4 8.7 0.4 2.1 4.1 6.0 0.7 7.2 7.6 4.2 5.7 7.6 4.4 1.6 7.8 9.1
11.1 13.0 14.2 6.9 13.8 11.6 7.6 5.1 18.1 14.6 16.4 16.2 16.2 16.3 3.6 21.8 4.7 15.9
1.8 4.6 8.8 1.8 13.4 9.5 3.5 0.9 17.4 7.4 8.8 12.0 10.5 8.7 0.8 20.2 3.1 6.8
T CCW CCW T CCW CCW CCW T CCW CCW CCW CCW CCW CCW T CCW CW CCW
PD PD PD INT PD PD PD PD PD PD PZ PD PD PZ d PZ INT PD
CCW, counterclockwise; CW, clockwise; D, dental; INT, internal distraction; P, paranasal; T, translation; Z, zygoma. Patient 15 underwent a conventional Le Fort III osteotomy.
824
F.P. Bouw et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 820e824
is a natural preference for counterclockwise movement, and distraction forces after LF III osteotomies should be oriented extremely caudally to prevent a counterclockwise rotation. In cases in which counterclockwise rotation occurred, an anterior open bite is often observed after the distraction period. To correct this anterior open bite, additional orthognathic surgery may be indicated. In a recently published article from our group, we showed that, on one hand, satisfactory results can be obtained after additional surgery (Nout et al., 2011). On the other hand, however, many patients with a postoperative malocclusion did not receive additional orthognathic surgery because of patient factors of which syndromicrelated mental retardation is the most important. Coping abilities and compliance in these patients is severely diminished. The protocol of the craniofacial team is as follows: in urgent need, for example, in case of severe obstructive sleep apnea or symptomatic exorbitism, age plays no role, and distraction is planned whenever needed. In case of a relative indication (malocclusion, aesthetics/ psychosocial concerns), the distraction is carried out between 8 and 12 years, or at the age of 18 years or more when skeletal maturity has been reached. The distraction is preferably not performed between 12 and 18 years, mainly because of puberty. In the case of additional orthognatic surgery, we prefer surgery after skeletal maturity has been reached. Unfortunately, most of the patients with an indication for additional surgery did not undergo this operation because of the lack of functional complaints or patient factors. Nowadays, more and more studies analyze the movement of the LF III segment in three dimensions. In contrast to other studies that used two-dimensional (2D) methods (Fearon, 2005; Meazzini et al., 2005), a 3D analysis has no interference with overlapping bony structures. Landmarks can be more accurately identified, which makes 3D analysis superior to a 2D analysis (Chien et al., 2009). The interobserver reliability was shown to be very good, which makes the reported method using the software program MevisLab reproducible. On the other hand, this method is laborious. Mathematical analysis of the length of the vector between both infraorbital foramens showed no significant different of the length of the vector pre- and postoperatively. Deformation of the LF III segment is unlikely in the study group. It seems that 2D analysis might be sufficient to predict segmental movements. In the past, fixation after LF III DO was achieved by means of wire attachment to the intraoral dental splint. Besides skeletal movement, dental movements including periodontal tissue loss with front teeth at risk were also observed. To exclude these dental problems and to enhance vector control, bony anchorage increasingly was used in craniofacial surgery. In this study, we showed that despite the combination of skeletal and dental anchorage of the fixation threads, unwanted counterclockwise movements still occur. Recent articles have shown that by using more rigid anchorage, improved vector control is possible even when solely dental anchorage is applied (Shetye et al., 2010; Lim et al., 2012). Fearon et al. demonstrated a more rigid anchorage between the dental splint with an additional midline superior point of traction n et al. reported at the base of the nasal bone (Fearon, 2005). Rolda better directional control of the segment by using self-cutting n screws through the nasal bone and piriform aperture (Rolda et al., 2011). According to Shetye et al., more rigid anchorage between the bar and the dental and/or skeletal anchorage points is preferable (Shetye et al., 2010). In taking into account literature findings with our data, it seems that more rigid anchorage as well as knowledge and understanding of the center of mass and other variables such as age, gender, previous surgery, etc. is necessary. Together these factors will improve prediction of the outcome of LF III DO and perhaps will reduce the number of additional orthognathic surgeries necessary because of unfavorable movement of the LF III segment.
5. Conclusion With LF III DO, a significant advancement is achievable, although the control of the vector of force was difficult in our study group and led to unwanted counterclockwise movements in a significant number of cases. By analyzing the movement of the LF III segment in three dimensions and relating it to the mode of fixation, no firm conclusions can be drawn about the ideal location and the number of anchorage points. Rigid fixation between the dental or skeletal fixation points and the external frame seems necessary and may lead to a more predictable result. Moreover, variables such as soft tissue envelope, age, mode of anchorage, and center of mass should be included in the design of force movement.
Sources of support No sources of support have been used.
Financial interest None of the authors has a financial interest in this study.
Competing interests None declared.
References Bachmayer DI, Ross RB, Munro IR: Maxillary growth following LeFort III advancement surgery in Crouzon, Apert, and Pfeiffer syndromes. Am J Orthod Dentofacial Orthop 90: 420e430, 1986 Chien PC, Parks ET, Eraso F, Hartsfield JK, Roberts WE, Ofner S: Comparison of reliability in anatomical landmark identification using two-dimensional digital cephalometrics and three-dimensional cone beam computed tomography in vivo. Dentomaxillofac Radiol 38: 262e273, 2009 Denny AD, Kalantarian B, Hanson PR: Rotation advancement of the midface by distraction osteogenesis. Plast Reconstr Surg 111: 1789e1799, 2003 discussion 1800 1803 Fearon JA: Halo distraction of the Le Fort III in syndromic craniosynostosis: a longterm assessment. Plast Reconstr Surg 115: 1524e1536, 2005 Figueroa AA, Polley JW, Figueroa AD: Biomechanical considerations for distraction of the monobloc, Le Fort III, and Le Fort I segments. Plast Reconstr Surg 126: 1005e1013, 2010 Kaban LB, Conover M, Mulliken JB: Midface position after Le Fort III advancement: a long-term follow-up study. Cleft Palate J 23(Suppl. 1): 75e77, 1986 Lim H, Ko EW, Lo LJ: Le Fort III distraction osteogenesis: modification of the intraoral splint in the rigid external distraction. J Craniofac Surg 23: 856e858, 2012 McCarthy JG, La Trenta GS, Breitbart AS, Grayson BH, Bookstein FL: The Le Fort III advancement osteotomy in the child under 7 years of age. Plast Reconstr Surg 86: 633e646, 1990 discussion 647 649 Meazzini MC, Mazzoleni F, Caronni E, Bozzetti A: Le Fort III advancement osteotomy in the growing child affected by Crouzon's and Apert's syndromes: presurgical and postsurgical growth. J Craniofac Surg 16: 369e377, 2005 Nanda R: Protraction of maxilla in rhesus monkeys by controlled extraoral forces. Am J Orthod 74: 121e141, 1978 Nout E, Cesteleyn LL, van der Wal KG, van Adrichem LN, Mathijssen IM, Wolvius EB: Advancement of the midface, from conventional Le Fort III osteotomy to Le Fort III distraction: review of the literature. Int J Oral Maxillofac Surg 37: 781e789, 2008 Nout E, Koudstaal MJ, Wolvius EB, Van der Wal KG: Additional orthognathic surgery following Le Fort III and monobloc advancement. Int J Oral Maxillofac Surg 40: 679e684, 2011 Nout E, van Bezooijen JS, Koudstaal MJ, Veenland JF, Hop WC, Wolvius EB, 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 40: 223e228, 2012 n JC, Moralis A, Dendorfer S, Witte J, Reicheneder C: Controlled central Rolda advancement of the midface after Le Fort III osteotomy by a 3-point skeletal anchorage. J Craniofac Surg 22: 2384e2386, 2011 Shetye PR, Giannoutsos E, Grayson BH, McCarthy JG: Le Fort III distraction: part I. Controlling position and vectors of the midface segment. Plast Reconstr Surg 124: 871e878, 2009 Shetye PR, Grayson BH, McCarthy JG: Le Fort III distraction: controlling position and path of the osteotomized midface segment on a rigid platform. J Craniofac Surg 21: 1118e1121, 2010