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O.313 Finite elements analysis of the human facial skeleton
86
Journal of Cranio-Maxillofacial Surgery 34(2006) Suppl. S1
Methods: The same standardized pre-operative evaluation was generally used for all patients. All cases are thoroughly assessed and well documented by clinical, photographic and radiographic data. A coronal surgical approach allows a wide access to the orbits and furthermore to other aesthetic and maxillofacial procedures. The surgical technique is well illustrated. Calvarian split bone grafts are positioned intraorbitally under the periostium in order to correct enophthalmos. Results: Post-operative photographs show the aesthetic improvement and control CT-scans showed no bone resorption. Conclusion: Autologous calvarian split bone grafts are widely used for the treatment of post-traumatic unilateral or bilateral orbital defects with enophthalmos. Moreover, this technique can also be used successfully for the treatment of primary enophthalmos combined simultaneously with other aesthetic or maxillofacial procedures. O.311 Facial Aesthetics: Attractiveness of specific changes of the orbital region I.N. Springer1 , B. Wannicke2 , P.H. Warnke1 , O. Zernial1 , J. Wiltfang1 , H. Terheyden1 , S. Wolfart1 . 1 Department of Oral and Maxillofacial Surgery, University of Kiel, Germany; 2 Department of Conservative Dentistry and Periodontology, University of Kiel, Germany; 3 Department of Prosthodontics, Propaedeutics and Dental Materials, University of Kiel, Germany Introduction and Objectives: The tilt of the intercanthal axis (=canthal tilt) influences the attractiveness of the human face. Aim of the present study was to assess standardized unilateral asymmetrical and bilateral symmetrical changes of the canthal tilt. Materials/methods: Four sets of images showing the orbital region of four different people contained one computermanipulated symmetric image, and 24 further computermanipulated images with different standardized symmetrical and asymmetrical changes of the canthal tilt (4º, 6º and 9º to normal), the center of motion being located medially or laterally. Judges (n = 250), ranked each picture of one randomized set for attractiveness on a visual-analogue scale. Results: The pictures were grouped into 5 different levels of attractiveness which were highly significantly different (p < 0.001). Within the most attractive level were symmetrical reference pictures as well as slight (4) asymmetrical or symmetrical upward tilts of the lateral canthus. Movements of 6 or more laterally, and of 4 or more medially were significantly more attractive when symmetrical than asymmetrical (p < 0.001). Tilts of the lateral canthus were significantly better tolerated than tilts of the medial canthus (p < 0.001). Medial and lateral upward rotations were significantly better tolerated than downward rotations (p < 0.001). Findings were reproducible (rp = 0.814, p < 0.001). Conclusions: Negative impact of changes of the orbital region on facial attractiveness increases from lateral to medial and from cranial to caudal. Small asymmetrical or symmetrical variations of the lateral canthus do not influence facial attractiveness negatively.
Abstracts, EACFMS XVIII Congress Thursday, 14 September 2006, 8.30−8.50
Hall 6
Facial trauma: hardware O.312 Resorption of biodegradable plates – An in vivo study S. Jank1 , P. Obrist2 , H. Strobl1 , B. Norer1 . 1 Department of Oral and Craniomaxillofacial Surgery, Austria, Medical University of Innsbruck; 2 Wagner-Jauregg Hospital Linz, Austria Introduction and Objectives: Biodegradable materials are described in the literature as an alternative to titanium for trauma management in the oral and maxillofacial region. The aim of the study was to get histological specimen of the biodegradable material and the surrounding tissue during the process of resorption. Materials and Methods: During a period of 12 months 12 patients undergoing a Le-Fort-I Osteotomy received 2 titanium plates and 2 biodegradable plates (Stryker, Delta-System® ). The titanium plates were positioned posterior and the biodegradable plates were positioned anterior. One year after surgery the titanium plates were removed. Using the same approach for the removal of the titanium plates, a biopsy of the region of the position of the biodegradable plates was taken for histological investigation. The study was approved by the Ethical Commission of the University of Innsbruck. Results: In all patients the biodegradable plates were still in position and the resorption of the mass was only little after 1 year. The changes and tissue reaction patterns in general are very slight with a diffuse increase in fibrotic tissue near the foreign reaction. A significant correlation between the duration of implantation of the resorbable materials (cut: 14 months) and the histological diagnosis of a foreign body reaction and/or fibrosis was found. Conclusions: Resorbable plates cause a foreign body reaction with a big mass of material remaining in position one year after surgery. Further investigations have to be performed to get more information how long the resorbable material remains in its position until the resorption is complete.
O.313 Finite elements analysis of the human facial skeleton O. Richard, P. Olivi, C. Chossegros, L. Guyot. Sce Chir. Maxillo-Faciale et plastique de la face, Hopital Nord, Marseille, France Introduction and Objectives: In the field of numerical simulation, the finite element method provides a virtual tool to study human tolerance under crash situations. Because of the complexity of the facial skeleton, finite elements models of the head often focus on the skull and the brain. Objective of this study is to make a finite element model of the human facial bones to perform numerical simulation of stress dispersion on the facial bones in response to impact. Material and Methods: The three-dimensional (3-D) geometry of the facial skeleton was automaticly and manually extracted from TDM images. The resulting geometry was then turned into a segmented mechanical component (using the finite element method). Validation of this model is made with comparison of impact response of the numerical model to facial bones fractures found in the literature and impact studies on anatomical human models. Result: A finite element model of the skull made of 67667 2D elements (trias) representing the cortical bone and 342084 3D elements (tetras) representing spongious bone is presented. Geometry distortion of all elements is near 0%.
Oral Presentations
Facial trauma: miscellaneous
Conclusion: The result is a valuable tool to improve the knowledge of injury mechanism involved in facial impacts.
Thursday, 14 September 2006, 8.50−9.40
87
Conclusion: By precise reduction of NOE fractures anatomic reconstruction and good function of the nasofrontal drainage with adequate frontal sinus function were achieved. Due to reported late complications a long-term follow-up is recommended.
Hall 6
Facial trauma: miscellaneous O.314 Midfacial fractures: primary treatment and treatment of sequelae L. Clauser, R. Tieghi. Department of Maxillofacial Surgery, S. Anna Hospital, Ferrara, Italy Introduction and Objectives: In recent years many advances have been made in the treatment of midfacial fractures of the middle third of the face, both in surgical techniques and in materials for stabilization and fixation. Materials and Methods: The importance of clinical and radiological pre-operative assessment is stressed and also the choice of the most suitable therapeutic approach for the different type of fractures, considering recent tendencies towards minimally invasive procedures to achieve better aesthetic results. Results: The use of rigid fixation with mini and micro plates has greatly improved treatment strategies, due to their easy adaptability and greater stabilization of the fracture site, condition necessary for correct recovery of the facial skeleton dimensions, ensuring that good dental occlusion and correct three-dimensional (3D) facial projection are maintained. Conclusion: Aim of the present work is to analyse the different treatment strategies and recent developments in the management of midfacial fractures, focusing not only on the functional but also on the aesthetic results and in the treatment of sequelae. O.315 Functional reconstruction of the nasofrontal duct in nasoorbitoethmoid fractures R. Sch¨on, N. Weyer, M. Metzger, R. Schmelzeisen. Deptartment of Craniomaxillofacial Surgery, University Clinic Freiburg i.Br., Germany Purpose: Following the literature the indication for obliteration versus reconstruction in frontal sinus and nasoorbitoethmoid (NOE) injuries with involvement of the “so-called” nasofrontal duct remains controversial. Long-term results following functional reconstruction of NOE fractures with involvement of the nasofrontal duct are demonstrated. Material and Method: Twelve consecutive patients with NOE fractures were treated during January 2000 and February 2006. In all 12 NOE fractures involvement of the nasofrontal duct region was noted in the preoperative CT scans. Precise open reduction and osteosynthesis using 1.0 and 1.3 titanium microplates (Synthes, Paoli, USA) and titanium Mesh in case of defect fractures were performed via coronal approaches. Dislocated bone fragments and lacerated mucosa where removed from the nasofrontal duct area. In medial orbital wall and orbital roof defects larger than 1 cm2 titanium mesh and in one case calvarium bone grafts were used. Defects smaller than 1 cm2 were reconstructed using resorbable foils (Ethisorb, Ethicon, Germany). The mean follow up was 2 years. Results: Uneventful healing following fracture reduction occurred in all 12 patients. Post-operative follow up by CT scans and digital volume tomography (cone-bean scan) verified anatomic reduction and well-pneumatized paranasal sinus. Functional reconstruction of the nasofrontal duct area was achieved. No mucosal swelling or impaired drainage of the frontal sinus and ethmoid cells were noted in longterm follow up.
O.316 How to avoid bursting the balloon during tracheostomy J.K. Thiruchelvam, L.H.H. Cheng. Department of Oral & Maxillofacial Surgery, Barts and The London Hospital and Homerton Hospital, London, UK Introduction: During tracheostomy, there is an increased risk of aspiration, loss of positive pressure ventilation and therefore inadequate oxygenation and sometimes hypercarbia due to the rupture of the endotracheal (ET) tube cuff. The procedure of creating a tracheal window could be prolonged due to calcified cartilage and bleeding from the tracheal mucosa. This increases the urgency between making the tracheal window and placement of a tracheostomy tube. Haemostasis with diathermy can cause a tracheal fire. A technique is described to avoid this urgency. Various measurements were recorded to substantiate the value of the technique. Methodology: Twelve patients had a modified surgical tracheostomy technique by positioning the end of the ET tube at the level of the carina, which prevents the rupture of the cuff. This maintains definitive airway and avoids the potential risks. Length of the cuff and the distance between the carina and the tracheal window were measured to substantiate the above technique. Results: Length of the cuff was around 6.8 cm. Distance between the carina and the site of the tracheotomy was 9.7 cm (7.5– 12.5 cm). There was no period of desaturation. Time taken to place the tracheostomy tube following the withdrawal of ET tube was minimal (3–6 s). Conclusion: We therefore recommend that the modified technique is essential during a tracheostomy procedure, especially in difficult patients. Also prior to shortening the ET tube in ITU, the end of the tube should be positioned at the carina with endoscopic guidance. In this way, should these patients require tracheostomy, a more controlled procedure can be performed. O.317 Transcutaneous reduction and external fixation of isolated anterior wall frontal sinus fractures F.A. Govoni, V.M. Marcelli, R. Pistilli, A. Nisii. Department of Maxillofacial Surgery (Dir. Dr. A. Nisii) San Filippo Neri Hospital, Rome, Italy Introduction and Objectives: The treatment of isolated fractures of the anterior wall of the frontal sinus, in particular when the fracture does not affect the nasofrontal duct, is not universally accepted considering the traditional open surgical technique that requires a bicoronal approach. The authors propose and discuss a new minimally invasive closed technique based on percutaneous pin-screwing reduction and external fixation of the anterior wall fragments of the frontal sinus. Material and Methods: Three clinical cases are reported. MandX-Fix system, originally manufactured by Leibinger for condylar fractures, has been used for the transcutaneous closed reduction of the bone fragments and for their external fixation to the frontal bone. All fractures were isolated non-comminuted fractures of the anterior wall of the frontal sinus, without associated lesions at the CT scan analysis, to the nasofrontal duct. External fixators were removed after 15 days post-operative. Clinical and radiological follow-up has been performed at 6 and at 12 months. Results: No complications have been reported during the 12 months follow-up. All the patients demonstrate non-significant
Journal of Cranio-Maxillofacial Surgery 34(2006) Suppl. S1
Methods: The same standardized pre-operative evaluation was generally used for all patients. All cases are thoroughly assessed and well documented by clinical, photographic and radiographic data. A coronal surgical approach allows a wide access to the orbits and furthermore to other aesthetic and maxillofacial procedures. The surgical technique is well illustrated. Calvarian split bone grafts are positioned intraorbitally under the periostium in order to correct enophthalmos. Results: Post-operative photographs show the aesthetic improvement and control CT-scans showed no bone resorption. Conclusion: Autologous calvarian split bone grafts are widely used for the treatment of post-traumatic unilateral or bilateral orbital defects with enophthalmos. Moreover, this technique can also be used successfully for the treatment of primary enophthalmos combined simultaneously with other aesthetic or maxillofacial procedures. O.311 Facial Aesthetics: Attractiveness of specific changes of the orbital region I.N. Springer1 , B. Wannicke2 , P.H. Warnke1 , O. Zernial1 , J. Wiltfang1 , H. Terheyden1 , S. Wolfart1 . 1 Department of Oral and Maxillofacial Surgery, University of Kiel, Germany; 2 Department of Conservative Dentistry and Periodontology, University of Kiel, Germany; 3 Department of Prosthodontics, Propaedeutics and Dental Materials, University of Kiel, Germany Introduction and Objectives: The tilt of the intercanthal axis (=canthal tilt) influences the attractiveness of the human face. Aim of the present study was to assess standardized unilateral asymmetrical and bilateral symmetrical changes of the canthal tilt. Materials/methods: Four sets of images showing the orbital region of four different people contained one computermanipulated symmetric image, and 24 further computermanipulated images with different standardized symmetrical and asymmetrical changes of the canthal tilt (4º, 6º and 9º to normal), the center of motion being located medially or laterally. Judges (n = 250), ranked each picture of one randomized set for attractiveness on a visual-analogue scale. Results: The pictures were grouped into 5 different levels of attractiveness which were highly significantly different (p < 0.001). Within the most attractive level were symmetrical reference pictures as well as slight (4) asymmetrical or symmetrical upward tilts of the lateral canthus. Movements of 6 or more laterally, and of 4 or more medially were significantly more attractive when symmetrical than asymmetrical (p < 0.001). Tilts of the lateral canthus were significantly better tolerated than tilts of the medial canthus (p < 0.001). Medial and lateral upward rotations were significantly better tolerated than downward rotations (p < 0.001). Findings were reproducible (rp = 0.814, p < 0.001). Conclusions: Negative impact of changes of the orbital region on facial attractiveness increases from lateral to medial and from cranial to caudal. Small asymmetrical or symmetrical variations of the lateral canthus do not influence facial attractiveness negatively.
Abstracts, EACFMS XVIII Congress Thursday, 14 September 2006, 8.30−8.50
Hall 6
Facial trauma: hardware O.312 Resorption of biodegradable plates – An in vivo study S. Jank1 , P. Obrist2 , H. Strobl1 , B. Norer1 . 1 Department of Oral and Craniomaxillofacial Surgery, Austria, Medical University of Innsbruck; 2 Wagner-Jauregg Hospital Linz, Austria Introduction and Objectives: Biodegradable materials are described in the literature as an alternative to titanium for trauma management in the oral and maxillofacial region. The aim of the study was to get histological specimen of the biodegradable material and the surrounding tissue during the process of resorption. Materials and Methods: During a period of 12 months 12 patients undergoing a Le-Fort-I Osteotomy received 2 titanium plates and 2 biodegradable plates (Stryker, Delta-System® ). The titanium plates were positioned posterior and the biodegradable plates were positioned anterior. One year after surgery the titanium plates were removed. Using the same approach for the removal of the titanium plates, a biopsy of the region of the position of the biodegradable plates was taken for histological investigation. The study was approved by the Ethical Commission of the University of Innsbruck. Results: In all patients the biodegradable plates were still in position and the resorption of the mass was only little after 1 year. The changes and tissue reaction patterns in general are very slight with a diffuse increase in fibrotic tissue near the foreign reaction. A significant correlation between the duration of implantation of the resorbable materials (cut: 14 months) and the histological diagnosis of a foreign body reaction and/or fibrosis was found. Conclusions: Resorbable plates cause a foreign body reaction with a big mass of material remaining in position one year after surgery. Further investigations have to be performed to get more information how long the resorbable material remains in its position until the resorption is complete.
O.313 Finite elements analysis of the human facial skeleton O. Richard, P. Olivi, C. Chossegros, L. Guyot. Sce Chir. Maxillo-Faciale et plastique de la face, Hopital Nord, Marseille, France Introduction and Objectives: In the field of numerical simulation, the finite element method provides a virtual tool to study human tolerance under crash situations. Because of the complexity of the facial skeleton, finite elements models of the head often focus on the skull and the brain. Objective of this study is to make a finite element model of the human facial bones to perform numerical simulation of stress dispersion on the facial bones in response to impact. Material and Methods: The three-dimensional (3-D) geometry of the facial skeleton was automaticly and manually extracted from TDM images. The resulting geometry was then turned into a segmented mechanical component (using the finite element method). Validation of this model is made with comparison of impact response of the numerical model to facial bones fractures found in the literature and impact studies on anatomical human models. Result: A finite element model of the skull made of 67667 2D elements (trias) representing the cortical bone and 342084 3D elements (tetras) representing spongious bone is presented. Geometry distortion of all elements is near 0%.
Oral Presentations
Facial trauma: miscellaneous
Conclusion: The result is a valuable tool to improve the knowledge of injury mechanism involved in facial impacts.
Thursday, 14 September 2006, 8.50−9.40
87
Conclusion: By precise reduction of NOE fractures anatomic reconstruction and good function of the nasofrontal drainage with adequate frontal sinus function were achieved. Due to reported late complications a long-term follow-up is recommended.
Hall 6
Facial trauma: miscellaneous O.314 Midfacial fractures: primary treatment and treatment of sequelae L. Clauser, R. Tieghi. Department of Maxillofacial Surgery, S. Anna Hospital, Ferrara, Italy Introduction and Objectives: In recent years many advances have been made in the treatment of midfacial fractures of the middle third of the face, both in surgical techniques and in materials for stabilization and fixation. Materials and Methods: The importance of clinical and radiological pre-operative assessment is stressed and also the choice of the most suitable therapeutic approach for the different type of fractures, considering recent tendencies towards minimally invasive procedures to achieve better aesthetic results. Results: The use of rigid fixation with mini and micro plates has greatly improved treatment strategies, due to their easy adaptability and greater stabilization of the fracture site, condition necessary for correct recovery of the facial skeleton dimensions, ensuring that good dental occlusion and correct three-dimensional (3D) facial projection are maintained. Conclusion: Aim of the present work is to analyse the different treatment strategies and recent developments in the management of midfacial fractures, focusing not only on the functional but also on the aesthetic results and in the treatment of sequelae. O.315 Functional reconstruction of the nasofrontal duct in nasoorbitoethmoid fractures R. Sch¨on, N. Weyer, M. Metzger, R. Schmelzeisen. Deptartment of Craniomaxillofacial Surgery, University Clinic Freiburg i.Br., Germany Purpose: Following the literature the indication for obliteration versus reconstruction in frontal sinus and nasoorbitoethmoid (NOE) injuries with involvement of the “so-called” nasofrontal duct remains controversial. Long-term results following functional reconstruction of NOE fractures with involvement of the nasofrontal duct are demonstrated. Material and Method: Twelve consecutive patients with NOE fractures were treated during January 2000 and February 2006. In all 12 NOE fractures involvement of the nasofrontal duct region was noted in the preoperative CT scans. Precise open reduction and osteosynthesis using 1.0 and 1.3 titanium microplates (Synthes, Paoli, USA) and titanium Mesh in case of defect fractures were performed via coronal approaches. Dislocated bone fragments and lacerated mucosa where removed from the nasofrontal duct area. In medial orbital wall and orbital roof defects larger than 1 cm2 titanium mesh and in one case calvarium bone grafts were used. Defects smaller than 1 cm2 were reconstructed using resorbable foils (Ethisorb, Ethicon, Germany). The mean follow up was 2 years. Results: Uneventful healing following fracture reduction occurred in all 12 patients. Post-operative follow up by CT scans and digital volume tomography (cone-bean scan) verified anatomic reduction and well-pneumatized paranasal sinus. Functional reconstruction of the nasofrontal duct area was achieved. No mucosal swelling or impaired drainage of the frontal sinus and ethmoid cells were noted in longterm follow up.
O.316 How to avoid bursting the balloon during tracheostomy J.K. Thiruchelvam, L.H.H. Cheng. Department of Oral & Maxillofacial Surgery, Barts and The London Hospital and Homerton Hospital, London, UK Introduction: During tracheostomy, there is an increased risk of aspiration, loss of positive pressure ventilation and therefore inadequate oxygenation and sometimes hypercarbia due to the rupture of the endotracheal (ET) tube cuff. The procedure of creating a tracheal window could be prolonged due to calcified cartilage and bleeding from the tracheal mucosa. This increases the urgency between making the tracheal window and placement of a tracheostomy tube. Haemostasis with diathermy can cause a tracheal fire. A technique is described to avoid this urgency. Various measurements were recorded to substantiate the value of the technique. Methodology: Twelve patients had a modified surgical tracheostomy technique by positioning the end of the ET tube at the level of the carina, which prevents the rupture of the cuff. This maintains definitive airway and avoids the potential risks. Length of the cuff and the distance between the carina and the tracheal window were measured to substantiate the above technique. Results: Length of the cuff was around 6.8 cm. Distance between the carina and the site of the tracheotomy was 9.7 cm (7.5– 12.5 cm). There was no period of desaturation. Time taken to place the tracheostomy tube following the withdrawal of ET tube was minimal (3–6 s). Conclusion: We therefore recommend that the modified technique is essential during a tracheostomy procedure, especially in difficult patients. Also prior to shortening the ET tube in ITU, the end of the tube should be positioned at the carina with endoscopic guidance. In this way, should these patients require tracheostomy, a more controlled procedure can be performed. O.317 Transcutaneous reduction and external fixation of isolated anterior wall frontal sinus fractures F.A. Govoni, V.M. Marcelli, R. Pistilli, A. Nisii. Department of Maxillofacial Surgery (Dir. Dr. A. Nisii) San Filippo Neri Hospital, Rome, Italy Introduction and Objectives: The treatment of isolated fractures of the anterior wall of the frontal sinus, in particular when the fracture does not affect the nasofrontal duct, is not universally accepted considering the traditional open surgical technique that requires a bicoronal approach. The authors propose and discuss a new minimally invasive closed technique based on percutaneous pin-screwing reduction and external fixation of the anterior wall fragments of the frontal sinus. Material and Methods: Three clinical cases are reported. MandX-Fix system, originally manufactured by Leibinger for condylar fractures, has been used for the transcutaneous closed reduction of the bone fragments and for their external fixation to the frontal bone. All fractures were isolated non-comminuted fractures of the anterior wall of the frontal sinus, without associated lesions at the CT scan analysis, to the nasofrontal duct. External fixators were removed after 15 days post-operative. Clinical and radiological follow-up has been performed at 6 and at 12 months. Results: No complications have been reported during the 12 months follow-up. All the patients demonstrate non-significant