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Rapid prototyping in craniofacial surgery: Using a positioning guide after zygomatic osteotomy – A case report
Journal of Cranio-Maxillo-Facial Surgery 39 (2011) 376e379
Contents lists available at ScienceDirect
Journal of Cranio-Maxillo-Facial Surgery journal homepage: www.jcmfs.com
Case report
Rapid prototyping in craniofacial surgery: Using a positioning guide after zygomatic osteotomy e A case reportq Christian Herlin a, b, *, Matthieu Koppe a, Jean-Luc Béziat a, Arnaud Gleizal a a b
Oral and Maxillo-Facial Surgery (Head: Jean-Luc Béziat), Hôpital de la Croix-Rousse, 103 Grand-Rue de la Croix-Rousse, 69317 Lyon, France Plastic and Cranio-Facial Unit, Hôpital Lapeyronie, 371 avenue du doyen Gaston Giraud, 34295 Montpellier, France
a r t i c l e i n f o
a b s t r a c t
Article history: Paper received 25 January 2010 Accepted 20 July 2010
Introduction: The management of post-traumatic deformity in the midface region poses challenges for the maxillofacial surgeon. Ensuring symmetry after zygomatic osteotomy can be difficult and precise positioning of the osteotomised bony fragments requires careful treatment planning. It may be necessary to use a coronal flap to allow the surgeon to compare the contralateral zygomatic bone to allow symmetrical reduction. The authors present a new technique for the positioning of osteotomised zygomatic bones using a combination of computer assisted surgical simulation and rapid prototyping. Method: A patient presented to our unit with a post-traumatic zygomatic deformity. Using surgical simulation software the displaced zygomatic bone was osteotomised and placed in the idéal position on a three-dimensional computed tomography scan (3D CT). The position was determined by reference to the contralateral zygoma. In addition the repositioning of the soft tissues was simulated. A surgical guide which allowed intraoperative positioning of the osteotomised zygoma was manufactured by a rapid prototyping process. Use of the guide allowed a minimally invasive approach to the affected zygoma. The post-operative results were compared to the predicted outcome. Results: The post-operative appearance was satisfactory and corresponded well with the predicted result. There was a significant reduction in operative time compared to the previous management of similar cases. Ó 2010 European Association for Cranio-Maxillo-Facial Surgery.
Keywords: Rapid prototyping Three-dimensional virtual planning Zygomatic osteotomy Soft tissue prediction
1. Introduction In craniofacial surgery involving the treatment of facial asymmetry, accurate positioning of the osteotomised bone fragments can be a technical challenge. In maxillo/mandibular orthognathic surgery dental splints provide accurate spatial positioning of the osteotomised maxilla and mandible. This is not possible in the mid and upper face and the surgeon often uses visual comparison between the osteotomised and normal side for positioning. The ability to transform CT data into three-dimensional models using stereolithography models (Kernan and Wimsatt, 2000; Murray et al., 2008) and more recently the use of simulation software (Murray et al., 2008; Marmulla and Niederdellmann, q This study has not been supported in the form of grants. * Corresponding author. 8, rue du cannau, Montpellier, France. Tel.: þ33 467338779. E-mail address: [email protected] (C. Herlin).
1999), have enabled surgeons to plan osteotomies and distraction osteogenesis in three dimensions and to adapt osteosynthesis plates prior to surgery. Using different scanning techniques allowed to predict soft tissue changes (Pektas et al., 2007; Donatsky et al., 2009). Using these relatively new scanning techniques to plan surgery it is now possible to design flaps and place implants in a predetermined position (Rohner et al., 2000; Rohner et al., 2002). It is now also possible to create a virtual model from a CT scan, and using rapid prototyping, go directly to manufacturing an implant or plate without the need for a physical model (Wagner et al., 2004; Petzold et al., 1999; Eufinger and Wehmoller, 1998). This technique can also be used to manufacture a template for outlining osteotomy cuts or resection margins (Leiggener et al., 2009). An alternative approach to the problem of accurate positioning of osteotomised bony segments has been the application of intraoperative navigation techniques. These were originally developed in neurosurgery (Watzinger et al., 1997; Marmulla and Niederdellmann, 1998; Klug et al., 2006; Lauer et al., 2006).
1010-5182/$ e see front matter Ó 2010 European Association for Cranio-Maxillo-Facial Surgery. doi:10.1016/j.jcms.2010.07.003
C. Herlin et al. / Journal of Cranio-Maxillo-Facial Surgery 39 (2011) 376e379
377
Fig. 1. Repositioning of the osteotomised zygoma using soft tissues as a reference.
Fig. 2. Initial position (yellow) and final position (red).
This paper describes a simple and reliable technique for positioning the osteotomised zygomatic bone in the treatment of posttraumatic deformity using computer assisted surgical simulation and a positioning template manufactured using rapid prototyping (RP) technology. 2. Case report A 63-year-old patient with pericarditis fell and sustained a displaced right zygomatic fracture. Because of her medical condition she was not fit for surgery for some months. She presented to the
unit of the Croix-Rousse hospital in Lyon with a post-traumatic deformity 6 months after the initial injury. It was felt that she would benefit from a repositioning osteotomy. Prior to this she underwent treatment planning to enable a positioning template to be constructed. A high resolution multislice 3D CT scan (helix with 0.6 mm slice thickness, 0.4 mm distance between slices, Phillips Brillance) was performed. CT data were stored using the DICOM medical image file format. Post-processing of the images was performed using Surgicase CMF software (MATERIALISEÒ, NV Leuven, Belgium). The initial step was to separate the skull into regions of interest (ROI). This automatic or semi-automatic separation is very accurate. In this case we isolated the zygomas from the rest of the skull. Once they had been segmented, the reconstructed ROI were extracted and converted into a 3D surface model in the .stl format using a 3D modelling program. The software then enabled us to reposition the right zygoma by mirroring the left zygoma, using the soft tissues as a reference (Fig. 1). The ROI of the affected zygoma were then osteotomized virtually, positioned with reference to the model and adjusted in the three dimensions using the changes in the soft tissues. Once the desired position was obtained, a guide was created to position the right zygoma during surgery with reference to a fixed position on the facial skeleton, which in this case was the inferior part of the fronto-nasal process (Fig. 2). A positioning guide was designed with OBL’s teamÒ, using the method described by Leiggener et al., (2009) for the manufacture of surgical templates for mandibular reconstruction. This produces a virtual 3D model in .stl format. The guide was designed with a 3D modelling program on a 1:1 scale using the anatomical features of the hard tissues after the simulation of the osteotomy. It was designed to be inserted through a standard sub-cilliary incision, although a transconjunctival approach could also have been used. Once the design was completed the guide was manufactured using selective laser sintering (SLS). This process uses a carbon dioxide laser beam to solidify a polyamide powder and build up the model in layers, using a slice thickness of 0.1 mm. Once completed, the
378
C. Herlin et al. / Journal of Cranio-Maxillo-Facial Surgery 39 (2011) 376e379
Fig. 3. Implementation guide by subciliary approach. Fig. 4. Control CT scan at 6 weeks. Overlapping bones and soft tissues.
guide was cleaned ultrasonically to remove all loose powder particles and sterilised using standard steam sterilisation. Exposure of the zygoma was achieved by subciliary, intra-oral and external canthal incisions (Fig. 3). The first step consisted of the initial positioning of the guide by its proximal part using two notches (in yellow) (Fig. 2). Once this position was located the guide was fixed with two screws then removed to allow the osteotomy to be performed using the technique described by Kawamoto (1982). This involved division of the zygoma on the fronto-zygomatic pillar, the maxillo-zygomatic suture and the zygomatic arch. The osteotomy was performed with piezosurgery (dental 3, MECTRONÒ, Sestri Levante GE, Italy) in order to obtain the thinnest and most precise cut lines. Once the zygoma was mobilized, the guide was repositioned and the zygoma placed in its final location (in red) with the help of the two other notches (Fig. 2). Osteosynthesis was then performed using three titanium miniplates. 3. Results The operation was straightforward and quick, with no intraoperative complications. A CT scan was performed 6 weeks after surgery. The position of the osteotomized zygoma was compared to that of the opposite side. We used the multiplanar reconstruction (MPR) mode to compare the projection of the two zygomas relative to the median plan and then we performed three-dimensional reconstruction. This reconstrcution was split in two, mirrored and superposed to compare the position of the two zygomas. We also compared the projection of soft tissues using the same technique. The position of the osteotomized zygoma corresponded to the pre-operative surgical simulation and gave very good projection of the soft tissues with restoration of a harmonious orbital contour (Fig. 4). 4. Discussion The treatment of post-traumatic deformity of the zygomatic region has two main objectives, to restore the projection of the zygomatic prominence and the symmetrical appearance of the face. This can be achieved in one of two ways. Firstly, by onlay grafting with either autologous osseous grafts (iliac crest, rib, calvaria or mandible) or synthetic grafts (Carboni et al., 2002) or, alternatively,
with a repositioning osteotomy (Freihofer and Borstlap, 1989). Grating techniques are unpredictable and many of the materials used are difficult to contour accurately. This can result in secondary deformity that may require further surgery. When using grafting techniques bone remains the gold standard, but this does require a donor site and its accompanying morbidities. A repositioning osteotomy is thought to give superior results by several authors (Carboni et al., 2002; Freihofer and Borstlap, 1989; Becelli et al., 2002). Osteotomies of the lower and midface can make use of the dental occlusion as reference points for accurate positioning of maxillary and mandibular osteotomies. When carrying out repositioning surgery on the lateral midface there are no such reference points for positioning the osteotomised segments. In addition accurate location of these segments can be difficult because of scarring and distortion of the surrounding and overlying tissues. As a result the surgeon may not achieve a satisfactory aesthetic or functional outcome (Murray et al., 2008; Marmulla and Niederdellmann, 1999; Watzinger et al., 1997; Marmulla and Niederdellmann, 1998; Klug et al., 2006; Becelli et al., 2002). In order to achieve as good an outcome as possible prior to the availability of repositioning guides such as we have described it has been necessary to use a coronal flap to expose the contralateral (normal) side for direct comparison and enable symmetrical reduction by direct view. Alternatively intraoperative navigation with a minimally invasive approach has been advocated by some authors, but this is a very expensive technique requiring extended theatre time and an experienced surgical team. The technique we have described employs advances in virtual modelling and rapid prototyping. Eliminating the need for a stereolithographic model reduces the time and costs of treatment planning. The positioning guide is simple to design and manufacture and the material is rigid enough to obtain a precise and reproducible position for the osteotomised segment prior to osteosynthesis. The surgical technique required is straightforward and the operating time was relatively short. Although the technique we have used has been published previously we believe this is the first time it has been described in a repositioning osteotomy of the zygoma. We believe it has applications in other post-traumatic surgical procedures, in oncological surgery and the correction of malformations.
C. Herlin et al. / Journal of Cranio-Maxillo-Facial Surgery 39 (2011) 376e379
5. Conclusion The technique we have described, using surgical simulation and rapid prototyping, is a simple and accurate method for positioning and rigidly fixing an osteotomised zygomatic bone segment. It avoids the need for a coronal approach or the need to harvest bone for a graft. It reduces operating time and costs without compromising an excellent outcome. References Becelli R, Carboni A, Cerulli G, Perugini M, Iannetti G: Delayed and inadequately treated malar fractures: evolution in the treatment, presentation of 77 cases, and review of the literature. Aesthetic Plast Surg 26: 134e138, 2002 Carboni A, Gasparini G, Perugini M, Renzi G, Matteini C, Becelli R: Evaluation of homologous bone graft versus biomaterials in the aesthetic restoration of the middle third of the face. Minerva Chir 57: 283e287, 2002 Donatsky O, Bjorn-Jorgensen J, Hermund NU, Nielsen H, Holmqvist-Larsen M, Nerder PH: Accuracy of combined maxillary and mandibular repositioning and of soft tissue prediction in relation to maxillary antero-superior repositioning combined with mandibular set back. A computerized cephalometric evaluation of the immediate postsurgical outcome using the TIOPS planning system. J Craniomaxillofac Surg 37: 279e284, 2009 Eufinger H, Wehmoller M: Individual prefabricated titanium implants in reconstructive craniofacial surgery: clinical and technical aspects of the first 22 cases. Plast Reconstr Surg 102: 300e308, 1998 Freihofer PM, Borstlap WA: Reconstruction of the zygomatic area. A comparison between osteotomy and onlay techniques. J Craniomaxillofac Surg 17: 243e248, 1989 Kawamoto Jr HK: Late posttraumatic enophthalmos: a correctable deformity? Plast Reconstr Surg 69: 423e432, 1982 Kernan BT, Wimsatt 3rd JA: Use of a stereolithography model for accurate, preoperative adaptation of a reconstruction plate. J Oral Maxillofac Surg 58: 349e351, 2000
379
Klug C, Schicho K, Ploder O, Yerit K, Watzinger F, Ewers R, et al: Point-to-point computer-assisted navigation for precise transfer of planned zygoma osteotomies from the stereolithographic model into reality. J Oral Maxillofac Surg 64: 550e559, 2006 Lauer G, Pradel W, Schneider M, Eckelt U: Efficacy of computer-assisted surgery in secondary orbital reconstruction. J Craniomaxillofac Surg 34: 299e305, 2006 Leiggener C, Messo E, Thor A, Zeilhofer HF, Hirsch JM: A selective laser sintering guide for transferring a virtual plan to real time surgery in composite mandibular reconstruction with free fibula osseous flaps. Int J Oral Maxillofac Surg 38: 187e192, 2009 Marmulla R, Niederdellmann H: Computer-aided navigation in secondary reconstruction of post-traumatic deformities of the zygoma. J Craniomaxillofac Surg 26: 68e69, 1998 Marmulla R, Niederdellmann H: Surgical planning of computer-assisted repositioning osteotomies. Plast Reconstr Surg 104: 938e944, 1999 Murray DJ, Edwards G, Mainprize JG, Antonyshyn O: Optimizing craniofacial osteotomies: applications of haptic and rapid prototyping technology. J Oral Maxillofac Surg 66: 1766e1772, 2008 Pektas ZO, Kircelli BH, Cilasun U, Uckan S: The accuracy of computer-assisted surgical planning in soft tissue prediction following orthognathic surgery. Int J Med Robot 3: 64e71, 2007 Petzold R, Zeilhofer HF, Kalender WA: Rapid protyping technology in medicine e basics and applications. Comput Med Imaging Graph 23: 277e284, 1999 Rohner D, Bucher P, Kunz C, Hammer B, Schenk RK, Prein J: Treatment of severe atrophy of the maxilla with the prefabricated free vascularized fibula flap. Clin Oral Implants Res 13: 44e52, 2002 Rohner D, Kunz C, Bucher P, Hammer B, Prein J: New possibilities for reconstructing extensive jaw defects with prefabricated microvascular fibula transplants and ITI implants. Mund Kiefer Gesichtschir 4: 365e372, 2000 Wagner JD, Baack B, Brown GA, Kelly J: Rapid 3-dimensional prototyping for surgical repair of maxillofacial fractures: a technical note. J Oral Maxillofac Surg 62: 898e901, 2004 Watzinger F, Wanschitz F, Wagner A, Enislidis G, Millesi W, Baumann A, et al: Computer-aided navigation in secondary reconstruction of post-traumatic deformities of the zygoma. J Craniomaxillofac Surg 25: 198e202, 1997
Contents lists available at ScienceDirect
Journal of Cranio-Maxillo-Facial Surgery journal homepage: www.jcmfs.com
Case report
Rapid prototyping in craniofacial surgery: Using a positioning guide after zygomatic osteotomy e A case reportq Christian Herlin a, b, *, Matthieu Koppe a, Jean-Luc Béziat a, Arnaud Gleizal a a b
Oral and Maxillo-Facial Surgery (Head: Jean-Luc Béziat), Hôpital de la Croix-Rousse, 103 Grand-Rue de la Croix-Rousse, 69317 Lyon, France Plastic and Cranio-Facial Unit, Hôpital Lapeyronie, 371 avenue du doyen Gaston Giraud, 34295 Montpellier, France
a r t i c l e i n f o
a b s t r a c t
Article history: Paper received 25 January 2010 Accepted 20 July 2010
Introduction: The management of post-traumatic deformity in the midface region poses challenges for the maxillofacial surgeon. Ensuring symmetry after zygomatic osteotomy can be difficult and precise positioning of the osteotomised bony fragments requires careful treatment planning. It may be necessary to use a coronal flap to allow the surgeon to compare the contralateral zygomatic bone to allow symmetrical reduction. The authors present a new technique for the positioning of osteotomised zygomatic bones using a combination of computer assisted surgical simulation and rapid prototyping. Method: A patient presented to our unit with a post-traumatic zygomatic deformity. Using surgical simulation software the displaced zygomatic bone was osteotomised and placed in the idéal position on a three-dimensional computed tomography scan (3D CT). The position was determined by reference to the contralateral zygoma. In addition the repositioning of the soft tissues was simulated. A surgical guide which allowed intraoperative positioning of the osteotomised zygoma was manufactured by a rapid prototyping process. Use of the guide allowed a minimally invasive approach to the affected zygoma. The post-operative results were compared to the predicted outcome. Results: The post-operative appearance was satisfactory and corresponded well with the predicted result. There was a significant reduction in operative time compared to the previous management of similar cases. Ó 2010 European Association for Cranio-Maxillo-Facial Surgery.
Keywords: Rapid prototyping Three-dimensional virtual planning Zygomatic osteotomy Soft tissue prediction
1. Introduction In craniofacial surgery involving the treatment of facial asymmetry, accurate positioning of the osteotomised bone fragments can be a technical challenge. In maxillo/mandibular orthognathic surgery dental splints provide accurate spatial positioning of the osteotomised maxilla and mandible. This is not possible in the mid and upper face and the surgeon often uses visual comparison between the osteotomised and normal side for positioning. The ability to transform CT data into three-dimensional models using stereolithography models (Kernan and Wimsatt, 2000; Murray et al., 2008) and more recently the use of simulation software (Murray et al., 2008; Marmulla and Niederdellmann, q This study has not been supported in the form of grants. * Corresponding author. 8, rue du cannau, Montpellier, France. Tel.: þ33 467338779. E-mail address: [email protected] (C. Herlin).
1999), have enabled surgeons to plan osteotomies and distraction osteogenesis in three dimensions and to adapt osteosynthesis plates prior to surgery. Using different scanning techniques allowed to predict soft tissue changes (Pektas et al., 2007; Donatsky et al., 2009). Using these relatively new scanning techniques to plan surgery it is now possible to design flaps and place implants in a predetermined position (Rohner et al., 2000; Rohner et al., 2002). It is now also possible to create a virtual model from a CT scan, and using rapid prototyping, go directly to manufacturing an implant or plate without the need for a physical model (Wagner et al., 2004; Petzold et al., 1999; Eufinger and Wehmoller, 1998). This technique can also be used to manufacture a template for outlining osteotomy cuts or resection margins (Leiggener et al., 2009). An alternative approach to the problem of accurate positioning of osteotomised bony segments has been the application of intraoperative navigation techniques. These were originally developed in neurosurgery (Watzinger et al., 1997; Marmulla and Niederdellmann, 1998; Klug et al., 2006; Lauer et al., 2006).
1010-5182/$ e see front matter Ó 2010 European Association for Cranio-Maxillo-Facial Surgery. doi:10.1016/j.jcms.2010.07.003
C. Herlin et al. / Journal of Cranio-Maxillo-Facial Surgery 39 (2011) 376e379
377
Fig. 1. Repositioning of the osteotomised zygoma using soft tissues as a reference.
Fig. 2. Initial position (yellow) and final position (red).
This paper describes a simple and reliable technique for positioning the osteotomised zygomatic bone in the treatment of posttraumatic deformity using computer assisted surgical simulation and a positioning template manufactured using rapid prototyping (RP) technology. 2. Case report A 63-year-old patient with pericarditis fell and sustained a displaced right zygomatic fracture. Because of her medical condition she was not fit for surgery for some months. She presented to the
unit of the Croix-Rousse hospital in Lyon with a post-traumatic deformity 6 months after the initial injury. It was felt that she would benefit from a repositioning osteotomy. Prior to this she underwent treatment planning to enable a positioning template to be constructed. A high resolution multislice 3D CT scan (helix with 0.6 mm slice thickness, 0.4 mm distance between slices, Phillips Brillance) was performed. CT data were stored using the DICOM medical image file format. Post-processing of the images was performed using Surgicase CMF software (MATERIALISEÒ, NV Leuven, Belgium). The initial step was to separate the skull into regions of interest (ROI). This automatic or semi-automatic separation is very accurate. In this case we isolated the zygomas from the rest of the skull. Once they had been segmented, the reconstructed ROI were extracted and converted into a 3D surface model in the .stl format using a 3D modelling program. The software then enabled us to reposition the right zygoma by mirroring the left zygoma, using the soft tissues as a reference (Fig. 1). The ROI of the affected zygoma were then osteotomized virtually, positioned with reference to the model and adjusted in the three dimensions using the changes in the soft tissues. Once the desired position was obtained, a guide was created to position the right zygoma during surgery with reference to a fixed position on the facial skeleton, which in this case was the inferior part of the fronto-nasal process (Fig. 2). A positioning guide was designed with OBL’s teamÒ, using the method described by Leiggener et al., (2009) for the manufacture of surgical templates for mandibular reconstruction. This produces a virtual 3D model in .stl format. The guide was designed with a 3D modelling program on a 1:1 scale using the anatomical features of the hard tissues after the simulation of the osteotomy. It was designed to be inserted through a standard sub-cilliary incision, although a transconjunctival approach could also have been used. Once the design was completed the guide was manufactured using selective laser sintering (SLS). This process uses a carbon dioxide laser beam to solidify a polyamide powder and build up the model in layers, using a slice thickness of 0.1 mm. Once completed, the
378
C. Herlin et al. / Journal of Cranio-Maxillo-Facial Surgery 39 (2011) 376e379
Fig. 3. Implementation guide by subciliary approach. Fig. 4. Control CT scan at 6 weeks. Overlapping bones and soft tissues.
guide was cleaned ultrasonically to remove all loose powder particles and sterilised using standard steam sterilisation. Exposure of the zygoma was achieved by subciliary, intra-oral and external canthal incisions (Fig. 3). The first step consisted of the initial positioning of the guide by its proximal part using two notches (in yellow) (Fig. 2). Once this position was located the guide was fixed with two screws then removed to allow the osteotomy to be performed using the technique described by Kawamoto (1982). This involved division of the zygoma on the fronto-zygomatic pillar, the maxillo-zygomatic suture and the zygomatic arch. The osteotomy was performed with piezosurgery (dental 3, MECTRONÒ, Sestri Levante GE, Italy) in order to obtain the thinnest and most precise cut lines. Once the zygoma was mobilized, the guide was repositioned and the zygoma placed in its final location (in red) with the help of the two other notches (Fig. 2). Osteosynthesis was then performed using three titanium miniplates. 3. Results The operation was straightforward and quick, with no intraoperative complications. A CT scan was performed 6 weeks after surgery. The position of the osteotomized zygoma was compared to that of the opposite side. We used the multiplanar reconstruction (MPR) mode to compare the projection of the two zygomas relative to the median plan and then we performed three-dimensional reconstruction. This reconstrcution was split in two, mirrored and superposed to compare the position of the two zygomas. We also compared the projection of soft tissues using the same technique. The position of the osteotomized zygoma corresponded to the pre-operative surgical simulation and gave very good projection of the soft tissues with restoration of a harmonious orbital contour (Fig. 4). 4. Discussion The treatment of post-traumatic deformity of the zygomatic region has two main objectives, to restore the projection of the zygomatic prominence and the symmetrical appearance of the face. This can be achieved in one of two ways. Firstly, by onlay grafting with either autologous osseous grafts (iliac crest, rib, calvaria or mandible) or synthetic grafts (Carboni et al., 2002) or, alternatively,
with a repositioning osteotomy (Freihofer and Borstlap, 1989). Grating techniques are unpredictable and many of the materials used are difficult to contour accurately. This can result in secondary deformity that may require further surgery. When using grafting techniques bone remains the gold standard, but this does require a donor site and its accompanying morbidities. A repositioning osteotomy is thought to give superior results by several authors (Carboni et al., 2002; Freihofer and Borstlap, 1989; Becelli et al., 2002). Osteotomies of the lower and midface can make use of the dental occlusion as reference points for accurate positioning of maxillary and mandibular osteotomies. When carrying out repositioning surgery on the lateral midface there are no such reference points for positioning the osteotomised segments. In addition accurate location of these segments can be difficult because of scarring and distortion of the surrounding and overlying tissues. As a result the surgeon may not achieve a satisfactory aesthetic or functional outcome (Murray et al., 2008; Marmulla and Niederdellmann, 1999; Watzinger et al., 1997; Marmulla and Niederdellmann, 1998; Klug et al., 2006; Becelli et al., 2002). In order to achieve as good an outcome as possible prior to the availability of repositioning guides such as we have described it has been necessary to use a coronal flap to expose the contralateral (normal) side for direct comparison and enable symmetrical reduction by direct view. Alternatively intraoperative navigation with a minimally invasive approach has been advocated by some authors, but this is a very expensive technique requiring extended theatre time and an experienced surgical team. The technique we have described employs advances in virtual modelling and rapid prototyping. Eliminating the need for a stereolithographic model reduces the time and costs of treatment planning. The positioning guide is simple to design and manufacture and the material is rigid enough to obtain a precise and reproducible position for the osteotomised segment prior to osteosynthesis. The surgical technique required is straightforward and the operating time was relatively short. Although the technique we have used has been published previously we believe this is the first time it has been described in a repositioning osteotomy of the zygoma. We believe it has applications in other post-traumatic surgical procedures, in oncological surgery and the correction of malformations.
C. Herlin et al. / Journal of Cranio-Maxillo-Facial Surgery 39 (2011) 376e379
5. Conclusion The technique we have described, using surgical simulation and rapid prototyping, is a simple and accurate method for positioning and rigidly fixing an osteotomised zygomatic bone segment. It avoids the need for a coronal approach or the need to harvest bone for a graft. It reduces operating time and costs without compromising an excellent outcome. References Becelli R, Carboni A, Cerulli G, Perugini M, Iannetti G: Delayed and inadequately treated malar fractures: evolution in the treatment, presentation of 77 cases, and review of the literature. Aesthetic Plast Surg 26: 134e138, 2002 Carboni A, Gasparini G, Perugini M, Renzi G, Matteini C, Becelli R: Evaluation of homologous bone graft versus biomaterials in the aesthetic restoration of the middle third of the face. Minerva Chir 57: 283e287, 2002 Donatsky O, Bjorn-Jorgensen J, Hermund NU, Nielsen H, Holmqvist-Larsen M, Nerder PH: Accuracy of combined maxillary and mandibular repositioning and of soft tissue prediction in relation to maxillary antero-superior repositioning combined with mandibular set back. A computerized cephalometric evaluation of the immediate postsurgical outcome using the TIOPS planning system. J Craniomaxillofac Surg 37: 279e284, 2009 Eufinger H, Wehmoller M: Individual prefabricated titanium implants in reconstructive craniofacial surgery: clinical and technical aspects of the first 22 cases. Plast Reconstr Surg 102: 300e308, 1998 Freihofer PM, Borstlap WA: Reconstruction of the zygomatic area. A comparison between osteotomy and onlay techniques. J Craniomaxillofac Surg 17: 243e248, 1989 Kawamoto Jr HK: Late posttraumatic enophthalmos: a correctable deformity? Plast Reconstr Surg 69: 423e432, 1982 Kernan BT, Wimsatt 3rd JA: Use of a stereolithography model for accurate, preoperative adaptation of a reconstruction plate. J Oral Maxillofac Surg 58: 349e351, 2000
379
Klug C, Schicho K, Ploder O, Yerit K, Watzinger F, Ewers R, et al: Point-to-point computer-assisted navigation for precise transfer of planned zygoma osteotomies from the stereolithographic model into reality. J Oral Maxillofac Surg 64: 550e559, 2006 Lauer G, Pradel W, Schneider M, Eckelt U: Efficacy of computer-assisted surgery in secondary orbital reconstruction. J Craniomaxillofac Surg 34: 299e305, 2006 Leiggener C, Messo E, Thor A, Zeilhofer HF, Hirsch JM: A selective laser sintering guide for transferring a virtual plan to real time surgery in composite mandibular reconstruction with free fibula osseous flaps. Int J Oral Maxillofac Surg 38: 187e192, 2009 Marmulla R, Niederdellmann H: Computer-aided navigation in secondary reconstruction of post-traumatic deformities of the zygoma. J Craniomaxillofac Surg 26: 68e69, 1998 Marmulla R, Niederdellmann H: Surgical planning of computer-assisted repositioning osteotomies. Plast Reconstr Surg 104: 938e944, 1999 Murray DJ, Edwards G, Mainprize JG, Antonyshyn O: Optimizing craniofacial osteotomies: applications of haptic and rapid prototyping technology. J Oral Maxillofac Surg 66: 1766e1772, 2008 Pektas ZO, Kircelli BH, Cilasun U, Uckan S: The accuracy of computer-assisted surgical planning in soft tissue prediction following orthognathic surgery. Int J Med Robot 3: 64e71, 2007 Petzold R, Zeilhofer HF, Kalender WA: Rapid protyping technology in medicine e basics and applications. Comput Med Imaging Graph 23: 277e284, 1999 Rohner D, Bucher P, Kunz C, Hammer B, Schenk RK, Prein J: Treatment of severe atrophy of the maxilla with the prefabricated free vascularized fibula flap. Clin Oral Implants Res 13: 44e52, 2002 Rohner D, Kunz C, Bucher P, Hammer B, Prein J: New possibilities for reconstructing extensive jaw defects with prefabricated microvascular fibula transplants and ITI implants. Mund Kiefer Gesichtschir 4: 365e372, 2000 Wagner JD, Baack B, Brown GA, Kelly J: Rapid 3-dimensional prototyping for surgical repair of maxillofacial fractures: a technical note. J Oral Maxillofac Surg 62: 898e901, 2004 Watzinger F, Wanschitz F, Wagner A, Enislidis G, Millesi W, Baumann A, et al: Computer-aided navigation in secondary reconstruction of post-traumatic deformities of the zygoma. J Craniomaxillofac Surg 25: 198e202, 1997