CLINICAL STUDY
Surgical Guide Assistant Mandibular Distraction Osteogenesis and Sagittal Split Osteotomy in the Treatment of Hemifacial Microsomia Lei Shi, MD, Wei Liu, MD, Lin Yin, MD, Shi Feng, MD, Shuo Xu, MD, and Zhi-Yong Zhang, MD Background: Hemifacial microsomia is the second most common congenital craniofacial malformation after cleft lip/palate with a wide variety of pathologic expression in jaws, skeletal components, ears, and soft tissues. Among the deformities, mandibular hypoplasia is the most common and is the main component that affects facial asymmetry. Mandibular distraction osteogenesis is the mainstay treatment; however, the vector of device and osteotomy lines need to be well designed. We utilized the sagittal split osteotomy for mandibular distraction with rapid prototyping surgical guide plate, making a successful outcome. Methods: Hemifacial microsomia with unilateral Pruzansky II mandibular hypoplasia were selected in this study. Three-dimensional CT reconstructive data was put into Proplan CFM for preoperative designing and then manufacturing the surgical guide plate. The mandibular osteotomy and implantation of the internal distractor were performed through an intraoral approach aided with the prefabricated guide plate. Distraction began 7 days postoperation with a frequency of 1 mm/d and the distractor was kept in place 6 to 10 months after the first operation, then the distractor was removed. Results: From July 2012 to March 2014, 6 cases of Pruzansky II hemifacial microsomia aged from 7 to 11 years were treated with the technique mentioned above. The range of distraction extends from 20 to 30 mm. The facial asymmetry deformities were improved obviously and without any complication. Conclusions: Mandibular distraction osteogenesis by sagittal split osteotomy through rapid prototyping surgical guide plate provides certain advantages in the treatment of hemifacial microsomia. Key Words: Hemifacial microsomia, distraction osteogenesis, sagittal split osteotomy, rapid prototyping technique (J Craniofac Surg 2015;26: 498–500)
From the Department of Maxillofacial Surgery, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. Received October 20, 2014. Accepted for publication December 23, 2014. Address correspondence and reprint requests to Zhi-Yong Zhang, MD, Department of Maxillofacial Surgery, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Shi-Jing-Shan District, Beijing 100144, China; E-mail: [email protected] The authors report no conflicts of interest. This project was supported by PUMC Youth Fund (grant no. 33320140099) and supported by the Foundation of Clinical Application of Capital Characteristic Features Research Project (grant no. Z121107001012112). Copyright © 2015 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000001529
498
H
emifacial microsomia (HFM) is well known as a relatively common congenital craniofacial deformity.1 It is characterized by an underdeveloped side of the face and aural deformity. Mandibular distraction osteogenesis has been a mainstay treatment for patients with hemifacial microsomia. Because the facial asymmetry is a progressive distortion and the deformity is complex in 3-dimensional space,2 a favorable surgical outcome is dependent on accurate preoperative planning and prediction.3 The purpose of this study was to demonstrate internal mandibular distraction osteogenesis combining the unilateral sagittal split osteotomy in the treatment of hemifacial microsomia.
PATIENTS AND METHODS Six cases of hemifacial microsomia patients aged from 7 to 11 years underwent mandibular distraction osteogenesis at the Maxillofacial Surgery Center, Plastic Surgery Hospital of the Chinese Academy of Medical Sciences between July 2012 and March 2014. The clinical data are illustrated in Table 1. All the patients and their families provided written consent before they took part in the study, which was approved by the ethics committee of the hospital. Radiologic images (cephalometric and panoramic views) and computed tomographic scans were taken before and after surgery.
Preoperative Designing The preoperative CT data were imported into the software Proplan CMF 1.4 (Materialise, Leuven, Belgium) for 3-dimensional reconstruction. Anatomical structures, such as the tooth germs and inferior alveolar nerve, were located. Planes and anatomical landmarks, such as the Frankfort horizontal plane, occlusal plane, the condylion, gonion, and menton, were marked on the 3-dimensional craniofacial skeleton. We measured the angles and lengths such as occlusal angle, height of the ramus, intercondylar distance, and other data to evaluate facial asymmetry. Distractors were selected and placed on the mandible in the 3D model. The direction and position of the distractor were adjusted repeatedly until the ideal status was realized. Osteotomy lines were similar to Obwegeser’s classic sagittal split ramus osteotomy and were designed to avoid damaging the tooth germs and inferior alveolar nerve, taking advantage of the bony stock as much as possible (Fig. 1A). The surgical plan was exported as STL format document into Geomagic studio 11.0 (3D Systems, USA) to make a surgical guide designed as a result. The surgical guide was manufactured by a 3D printer with rapid prototyping technique (Figs. 1B–3).
Surgical Techniques The operation was performed under general anesthesia with the patient in a supine position. In the first stage, mandibular osteotomy and implantation of the internal distractor were performed through an intraoral approach. An intraoral vestibular incision and mucoperiosteal flap were performed
The Journal of Craniofacial Surgery • Volume 26, Number 2, March 2015
Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 26, Number 2, March 2015
Mandibular Distraction Osteogenesis
TABLE 1. Distribution of HFM Patients Age Patient (yr) 1 2 3 4 5 6 Mean
7 7 8 9 8 11 8.3
Sex
Classification (Pruzansky)
Distraction Distance (mm)
Period of Consolidation (mo)
Period of Follow-up (mo)
Male Female Male Male Male Female —
IIA IIA IIB IIB IIB IIB —
20 20 20 20 20 30 21.7
10 6 6 6 6 8 7
12 7 8 6 6 6 7.5
in the region of the planned osteotomy in the affected lateral mandible to expose the lateral ramus and posterior body. As designed before as Figure 2 revealed in the computer software Geomagic studio, the prefabricated guide plate was fitted to match the mandible. On the surgical guide, the linear groove indicates the line of osteotomy and the dot grooves indicate the fixed position of screws. We marked the osteotomy line along the surgical guide linear groove on the media and lateral cortex with a fissure bur. The medial line was performed in the usual manner just above and ending posterior to the lingual. Different from the classic sagittal split osteotomy, the lateral horizontal cortical osteotomy line was parallel to the occlusal plane, to especially extend the mandibular ramus. The distractor was also reshaped with the guide plate. After osteotomy, the distractor was fixed in position (Fig. 4). Seven days after surgery, the distraction was started at 1 mm/d. After the distraction was completed, the stabilizing period was continued to 6 to 8 months. Then we did the second-stage operation to remove the distractor.
RESULTS All patients tolerated the distraction process well without complications. Successful distraction was achieved with radiographic evidence of new bone formation. The average mandibular distraction was
FIGURE 1. A, Photograph displaying the osteotomy line of sagittal split osteotomy and the position, vector, and length of distractor. B, The guide highly matched the 3D craniofacial skeleton.
FIGURE 2. Final design of the surgical guide plate.
FIGURE 3. Rapid prototyping surgical guide plate.
30 mm, with a range of 21.7 mm. Mandible ramus expanded in height significantly. All patients had significant improvements in chin position and facial symmetry after distraction (Figs. 5).
DISCUSSION Hemifacial microsomia is a common congenital craniofacial malformation that affects the structures mainly derived from the first and second brachial arches. The clinical features can be from mild to very severe; the correction of mandibular deviation is the most important step for the management of these congenital deformities. For mild deformities without obvious mandibular deviation (Pruzansky I), surgical management can wait until maturation of the facial skeleton, but for severe forms (Pruzansky II, III), it has been widely accepted that the intervention should start earlier to facilitate harmonious and balanced development of the facial skeleton. The advantage of hemifacial microsomia distraction osteogenesis has made treatment possible in very young children.4 For distraction osteogenesis, vector selection and osteotomy design are very important in unilateral mandibular distraction for the most severe hemifacial microsomia patients. The dysplasia mandible is mainly refined to the ramus; thus, elongating the mandible in a vertical direction can increase the posterior facial height and disocclude the posterior dentition.5 For all of our patients, we selected the vertical distraction as the main vector, which can effectively increase the vertical height of the affected mandible, rotate the pogonion toward the central sagittal plane, and avoid obvious mandibular protrusion.6 For the patients with relatively small bony stock, sagittal split osteotomy provides more contact surface for callus formation, and the osteotomy line can be designed in an irregular fashion to avoid injury to the tooth germs and the inferior alveolar nerve. Stretching
FIGURE 4. Intraoral distraction osteogenesis with unilateral sagittal split osteotomy. The photograph displays the distractor that was fixed in position.
© 2015 Mutaz B. Habal, MD
Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
499
Shi et al
The Journal of Craniofacial Surgery • Volume 26, Number 2, March 2015
CONCLUSIONS In summary, the combination of sagittal split osteotomy and rapid prototyping technique provides certain advantages for distraction of the mandible in the treatment of hemifacial microsomia.
REFERENCES
FIGURE 5. A, Photograph displaying 3D-CT reconstruction of the craniofacial skeleton preoperation. B, Photograph displaying 3D-CT reconstruction of the craniofacial skeleton 6 months after the first operation. The facial asymmetry deformities were improved obviously and the mandibular distraction osteogenesis was very good.
injury during distraction can be avoided if sagittal split osteotomy is performed because the nerve is completely protected within the distal segment. Because orthodontic treatment will be needed after all the operations, preservation of tooth germs is also very important. Thus, sagittal split osteotomy is a safer method and preserves the nerve and tooth germs more than conventional osteotomy when used for mandibular distraction.7,8 Because the orientation of the device during mandibular osteodistraction has important biomechanical effects on the lateral force, virtual 3D planning and guidance of mandibular distraction osteogenesis is very important and necessary. With the help of the prefabricated guide plate, the manipulation of the operation can be realized not only more easily and precisely but also entirely the same as virtual designing plan before operation and without a few errors.6,9
500
1. McCarthy JG, Grayson BH, Coccaro PH, et al. Craniofacial microsomia. In: McCarthy JG, ed. Plastic Surgery. Vol. 4. Philadelphia, PA: Saunders, 1990:3054–3100. 2. Kaban LB. Mandibular asymmetry and the fourth dimension. J Craniofac Surg. 2009;20(Suppl 1):622–631. 3. Dec W, Peltomaki T, Warren SM, et al. The importance of vector selection in preoperative planning of unilateral mandibular distraction. Plast Reconstr Surg. 2008;121:2084–2092; discussion 2093–4. 4. McCarthy JG, Schreiber J, Karp N, et al. Lengthening the human mandible by gradual distraction. Plast Reconstr Surg. 1992;89:1–8; discussion 9–10. 5. Vendittelli BL, Dec W, Warren SM, et al. The importance of vector selection in preoperative planning of bilateral mandibular distraction. Plast Reconstr Surg. 2008;122:1144–1153. 6. Lei Shi, Lin Yin, HongYu Yin, et al. Using three-dimensional computer tomography reconstruction and distraction osteogenesis techniques for personalized correction on hemifacial microsomia. J Tissue Eng. 2011;7:154–156. 7. Choi JY, Hwang KG, Baek SH, et al. Original sagittal split osteotomy revisited for mandibular distraction. J Craniomaxillofac Surg. 2001; 29:165–173. 8. Altuna G, Walker DA, Freeman E. Rapid orthopedic lengthening of the mandible in primates by sagittal split osteotomy distraction osteogenesis: a pilot study. Int J Adult Orthodon Orthognath Surg. 1995;10:59–64. 9. Sun H, Li B, Zhao Z, et al. Error analysis of a CAD/CAM method for unidirectional mandibular distraction osteogenesis in the treatment of hemifacial microsomia. Br J Oral Maxillofac Surg. 2013;51:892–897.
© 2015 Mutaz B. Habal, MD
Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
Surgical Guide Assistant Mandibular Distraction Osteogenesis and Sagittal Split Osteotomy in the Treatment of Hemifacial Microsomia Lei Shi, MD, Wei Liu, MD, Lin Yin, MD, Shi Feng, MD, Shuo Xu, MD, and Zhi-Yong Zhang, MD Background: Hemifacial microsomia is the second most common congenital craniofacial malformation after cleft lip/palate with a wide variety of pathologic expression in jaws, skeletal components, ears, and soft tissues. Among the deformities, mandibular hypoplasia is the most common and is the main component that affects facial asymmetry. Mandibular distraction osteogenesis is the mainstay treatment; however, the vector of device and osteotomy lines need to be well designed. We utilized the sagittal split osteotomy for mandibular distraction with rapid prototyping surgical guide plate, making a successful outcome. Methods: Hemifacial microsomia with unilateral Pruzansky II mandibular hypoplasia were selected in this study. Three-dimensional CT reconstructive data was put into Proplan CFM for preoperative designing and then manufacturing the surgical guide plate. The mandibular osteotomy and implantation of the internal distractor were performed through an intraoral approach aided with the prefabricated guide plate. Distraction began 7 days postoperation with a frequency of 1 mm/d and the distractor was kept in place 6 to 10 months after the first operation, then the distractor was removed. Results: From July 2012 to March 2014, 6 cases of Pruzansky II hemifacial microsomia aged from 7 to 11 years were treated with the technique mentioned above. The range of distraction extends from 20 to 30 mm. The facial asymmetry deformities were improved obviously and without any complication. Conclusions: Mandibular distraction osteogenesis by sagittal split osteotomy through rapid prototyping surgical guide plate provides certain advantages in the treatment of hemifacial microsomia. Key Words: Hemifacial microsomia, distraction osteogenesis, sagittal split osteotomy, rapid prototyping technique (J Craniofac Surg 2015;26: 498–500)
From the Department of Maxillofacial Surgery, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. Received October 20, 2014. Accepted for publication December 23, 2014. Address correspondence and reprint requests to Zhi-Yong Zhang, MD, Department of Maxillofacial Surgery, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Shi-Jing-Shan District, Beijing 100144, China; E-mail: [email protected] The authors report no conflicts of interest. This project was supported by PUMC Youth Fund (grant no. 33320140099) and supported by the Foundation of Clinical Application of Capital Characteristic Features Research Project (grant no. Z121107001012112). Copyright © 2015 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000001529
498
H
emifacial microsomia (HFM) is well known as a relatively common congenital craniofacial deformity.1 It is characterized by an underdeveloped side of the face and aural deformity. Mandibular distraction osteogenesis has been a mainstay treatment for patients with hemifacial microsomia. Because the facial asymmetry is a progressive distortion and the deformity is complex in 3-dimensional space,2 a favorable surgical outcome is dependent on accurate preoperative planning and prediction.3 The purpose of this study was to demonstrate internal mandibular distraction osteogenesis combining the unilateral sagittal split osteotomy in the treatment of hemifacial microsomia.
PATIENTS AND METHODS Six cases of hemifacial microsomia patients aged from 7 to 11 years underwent mandibular distraction osteogenesis at the Maxillofacial Surgery Center, Plastic Surgery Hospital of the Chinese Academy of Medical Sciences between July 2012 and March 2014. The clinical data are illustrated in Table 1. All the patients and their families provided written consent before they took part in the study, which was approved by the ethics committee of the hospital. Radiologic images (cephalometric and panoramic views) and computed tomographic scans were taken before and after surgery.
Preoperative Designing The preoperative CT data were imported into the software Proplan CMF 1.4 (Materialise, Leuven, Belgium) for 3-dimensional reconstruction. Anatomical structures, such as the tooth germs and inferior alveolar nerve, were located. Planes and anatomical landmarks, such as the Frankfort horizontal plane, occlusal plane, the condylion, gonion, and menton, were marked on the 3-dimensional craniofacial skeleton. We measured the angles and lengths such as occlusal angle, height of the ramus, intercondylar distance, and other data to evaluate facial asymmetry. Distractors were selected and placed on the mandible in the 3D model. The direction and position of the distractor were adjusted repeatedly until the ideal status was realized. Osteotomy lines were similar to Obwegeser’s classic sagittal split ramus osteotomy and were designed to avoid damaging the tooth germs and inferior alveolar nerve, taking advantage of the bony stock as much as possible (Fig. 1A). The surgical plan was exported as STL format document into Geomagic studio 11.0 (3D Systems, USA) to make a surgical guide designed as a result. The surgical guide was manufactured by a 3D printer with rapid prototyping technique (Figs. 1B–3).
Surgical Techniques The operation was performed under general anesthesia with the patient in a supine position. In the first stage, mandibular osteotomy and implantation of the internal distractor were performed through an intraoral approach. An intraoral vestibular incision and mucoperiosteal flap were performed
The Journal of Craniofacial Surgery • Volume 26, Number 2, March 2015
Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 26, Number 2, March 2015
Mandibular Distraction Osteogenesis
TABLE 1. Distribution of HFM Patients Age Patient (yr) 1 2 3 4 5 6 Mean
7 7 8 9 8 11 8.3
Sex
Classification (Pruzansky)
Distraction Distance (mm)
Period of Consolidation (mo)
Period of Follow-up (mo)
Male Female Male Male Male Female —
IIA IIA IIB IIB IIB IIB —
20 20 20 20 20 30 21.7
10 6 6 6 6 8 7
12 7 8 6 6 6 7.5
in the region of the planned osteotomy in the affected lateral mandible to expose the lateral ramus and posterior body. As designed before as Figure 2 revealed in the computer software Geomagic studio, the prefabricated guide plate was fitted to match the mandible. On the surgical guide, the linear groove indicates the line of osteotomy and the dot grooves indicate the fixed position of screws. We marked the osteotomy line along the surgical guide linear groove on the media and lateral cortex with a fissure bur. The medial line was performed in the usual manner just above and ending posterior to the lingual. Different from the classic sagittal split osteotomy, the lateral horizontal cortical osteotomy line was parallel to the occlusal plane, to especially extend the mandibular ramus. The distractor was also reshaped with the guide plate. After osteotomy, the distractor was fixed in position (Fig. 4). Seven days after surgery, the distraction was started at 1 mm/d. After the distraction was completed, the stabilizing period was continued to 6 to 8 months. Then we did the second-stage operation to remove the distractor.
RESULTS All patients tolerated the distraction process well without complications. Successful distraction was achieved with radiographic evidence of new bone formation. The average mandibular distraction was
FIGURE 1. A, Photograph displaying the osteotomy line of sagittal split osteotomy and the position, vector, and length of distractor. B, The guide highly matched the 3D craniofacial skeleton.
FIGURE 2. Final design of the surgical guide plate.
FIGURE 3. Rapid prototyping surgical guide plate.
30 mm, with a range of 21.7 mm. Mandible ramus expanded in height significantly. All patients had significant improvements in chin position and facial symmetry after distraction (Figs. 5).
DISCUSSION Hemifacial microsomia is a common congenital craniofacial malformation that affects the structures mainly derived from the first and second brachial arches. The clinical features can be from mild to very severe; the correction of mandibular deviation is the most important step for the management of these congenital deformities. For mild deformities without obvious mandibular deviation (Pruzansky I), surgical management can wait until maturation of the facial skeleton, but for severe forms (Pruzansky II, III), it has been widely accepted that the intervention should start earlier to facilitate harmonious and balanced development of the facial skeleton. The advantage of hemifacial microsomia distraction osteogenesis has made treatment possible in very young children.4 For distraction osteogenesis, vector selection and osteotomy design are very important in unilateral mandibular distraction for the most severe hemifacial microsomia patients. The dysplasia mandible is mainly refined to the ramus; thus, elongating the mandible in a vertical direction can increase the posterior facial height and disocclude the posterior dentition.5 For all of our patients, we selected the vertical distraction as the main vector, which can effectively increase the vertical height of the affected mandible, rotate the pogonion toward the central sagittal plane, and avoid obvious mandibular protrusion.6 For the patients with relatively small bony stock, sagittal split osteotomy provides more contact surface for callus formation, and the osteotomy line can be designed in an irregular fashion to avoid injury to the tooth germs and the inferior alveolar nerve. Stretching
FIGURE 4. Intraoral distraction osteogenesis with unilateral sagittal split osteotomy. The photograph displays the distractor that was fixed in position.
© 2015 Mutaz B. Habal, MD
Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
499
Shi et al
The Journal of Craniofacial Surgery • Volume 26, Number 2, March 2015
CONCLUSIONS In summary, the combination of sagittal split osteotomy and rapid prototyping technique provides certain advantages for distraction of the mandible in the treatment of hemifacial microsomia.
REFERENCES
FIGURE 5. A, Photograph displaying 3D-CT reconstruction of the craniofacial skeleton preoperation. B, Photograph displaying 3D-CT reconstruction of the craniofacial skeleton 6 months after the first operation. The facial asymmetry deformities were improved obviously and the mandibular distraction osteogenesis was very good.
injury during distraction can be avoided if sagittal split osteotomy is performed because the nerve is completely protected within the distal segment. Because orthodontic treatment will be needed after all the operations, preservation of tooth germs is also very important. Thus, sagittal split osteotomy is a safer method and preserves the nerve and tooth germs more than conventional osteotomy when used for mandibular distraction.7,8 Because the orientation of the device during mandibular osteodistraction has important biomechanical effects on the lateral force, virtual 3D planning and guidance of mandibular distraction osteogenesis is very important and necessary. With the help of the prefabricated guide plate, the manipulation of the operation can be realized not only more easily and precisely but also entirely the same as virtual designing plan before operation and without a few errors.6,9
500
1. McCarthy JG, Grayson BH, Coccaro PH, et al. Craniofacial microsomia. In: McCarthy JG, ed. Plastic Surgery. Vol. 4. Philadelphia, PA: Saunders, 1990:3054–3100. 2. Kaban LB. Mandibular asymmetry and the fourth dimension. J Craniofac Surg. 2009;20(Suppl 1):622–631. 3. Dec W, Peltomaki T, Warren SM, et al. The importance of vector selection in preoperative planning of unilateral mandibular distraction. Plast Reconstr Surg. 2008;121:2084–2092; discussion 2093–4. 4. McCarthy JG, Schreiber J, Karp N, et al. Lengthening the human mandible by gradual distraction. Plast Reconstr Surg. 1992;89:1–8; discussion 9–10. 5. Vendittelli BL, Dec W, Warren SM, et al. The importance of vector selection in preoperative planning of bilateral mandibular distraction. Plast Reconstr Surg. 2008;122:1144–1153. 6. Lei Shi, Lin Yin, HongYu Yin, et al. Using three-dimensional computer tomography reconstruction and distraction osteogenesis techniques for personalized correction on hemifacial microsomia. J Tissue Eng. 2011;7:154–156. 7. Choi JY, Hwang KG, Baek SH, et al. Original sagittal split osteotomy revisited for mandibular distraction. J Craniomaxillofac Surg. 2001; 29:165–173. 8. Altuna G, Walker DA, Freeman E. Rapid orthopedic lengthening of the mandible in primates by sagittal split osteotomy distraction osteogenesis: a pilot study. Int J Adult Orthodon Orthognath Surg. 1995;10:59–64. 9. Sun H, Li B, Zhao Z, et al. Error analysis of a CAD/CAM method for unidirectional mandibular distraction osteogenesis in the treatment of hemifacial microsomia. Br J Oral Maxillofac Surg. 2013;51:892–897.
© 2015 Mutaz B. Habal, MD
Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
