Correction of the craniofacial framework by computer-assisted surgery and distraction osteogenesis

Angeborene und erworbene Varianten des Gesichtsschädelaufbaus stellen unverändert eine Herausforderung für den rekonstruktiv tätigen MKG-Chirurgen dar. Im Rahmen eines modularen Aufbaus werden in der vorliegenden kumulativen Habilitationsschrift zum Erwerb der „venia legendi“ für das Fachgebiet Mund-, Kiefer- und Gesichtschirurgie eigene klinisch-wissenschaftliche Beiträge dargestellt, die moderne Verfahren zur Planung und Korrektur von Varianten des kraniomaxillofazialen Skelettsystems beschreiben. Vor dem Hintergrund wissenschaftlicher Publikationen werden zwei verschiedene Themenkomplexe diskutiert. Ihre Kombination erlaubt die Realisierung verbesserter individueller Therapiekonzepte bei ausgewählten Patienten. Einen Schwerpunkt der vorliegenden Schrift bildet die Einbindung und Weiterentwicklung computer- assistierter Planungs- und Umsetzungsverfahren in die klinische Versorgung von Patienten mit Varianten des Schädelaufbaus: Es konnte dabei gezeigt werden, dass 1\. Durch Verwendung von DVT-Datensätzen patientenspezifische 3D-Modelle generiert werden können, die für kraniomaxillofaziale chirurgische Planungen geeignet sind. Dieses Vorgehen erleichtert den präoperativen Arbeitsablauf, erhöht den Patientenkomfort und reduziert den korrespondierenden administrativen Aufwand. 2\. Durch computer-assistierte Verfahren Splints für die Umsetzung kieferverlagernder Eingriffe gefertigt werden können, die in Präzision dem bisherigen Goldstandard (Techniker-gefertigte Splints) bei reduziertem Planungsaufwand ebenbürtig sind. 3.Computer-assistierte virtuelle Planungs- und Transfermöglichkeiten zukünftig eine zunehmende Rolle bei komplexen kraniomaxillofazialen Verlagerungen spielen werden. Den zweiten Schwerpunkt der vorliegenden Arbeit bildet die klinisch-wissenschaftliche Evaluation der Distraktionsosteogenese im Bereich des kraniomaxillofazialen Skelettsystems. Diese chirurgische Technik zur autologen Gewebevermehrung am Ort des Defizits wurde vor dem Hintergrund der über 10-jährigen klinischen Anwendung beschrieben. Dabei fanden Erkenntnisse eigener vorhergehender experimenteller Untersuchungen Eingang in die klinische Anwendung, so dass seither über 100 Distraktionsosteogenesen erfolgreich durchgeführt werden konnten. Ihr Langzeitverlauf wurde systematisch dokumentiert, analysiert und evaluiert: Im Hinblick auf Fallzahlen im MKG-chirurgischen Behandlungsspektrum spielt die Distraktionsosteogenese zwar eine eher untergeordnete Rolle, im Rahmen individueller Therapieplanungen hat sie bei Varianten des Schädelaufbaus in Kombination mit anderen rekonstruktiven chirurgischen Techniken einen erheblichen Stellenwert. Als Hauptanwendung hat sich im eigenen Patientenspektrum die Transpalatinaldistraktion zur individuellen Korrektur des transversalen maxillären Defizits mit oder ohne nachfolgende Bisslagekorrektur etabliert. Die Anwendung moderner computer-assistierter Verfahren und ihre Kombination mit Distraktionstechniken verbessert die Korrekturmöglichkeiten von skelettalen Varianten des Schädelaufbaus im Hinblick auf Planungs-, Transfer-, Dokumentations- und Evaluationsmöglichkeiten und stellt somit einen therapeutischen Fortschritt für betroffene Patienten dar.In reconstructive surgery inborn or acquired craniofacial deformities are still a challenge for craniomaxillofacial surgeons. This cumulative thesis for postdoctoral lecture qualification (Phd) describes within a modular setting different clinical and scientific approaches and contributions which improve the surgical management of patients who are affected by variations of the physiologic craniofacial framework. Contemporary planning and transfer tools for corrective craniomaxillofacial surgery are described focussing on two special aspects which are highlighted by scientific publications. Computer- assisted surgery supports craniomaxillofacial corrections. It could be demonstrated that 1.Patient-specific 3-dimensional models based on Cone beam computed tomography (CB-CT) DICOM-datasets are appropriate for craniomaxillofacial surgical planning. It could be shown that time and effort for the manufacturing of these models was reduced when compared to the well established protocol using Multi slice computed tomography (MSCT). 2.Computer- assisted technology is able to provide splints for orthognathic surgery which are comparable to splints that are manufactured by dental technicians. 3 .Computer-assisted technology improves planning, transfer, documentation and evaluation of complex craniofacial corrections and is likely to have a more important role in future The second aspect of this thesis focuses on the significance of distraction osteogenesis (DO) for craniomaxillofacial corrective surgery. Based on experimental data this surgical technique has been applied successfully more than 100 times during the last 10 years by the author. Each distraction case has been documented prospectively and evaluated with regard to long-term results. According to these results distraction osteogenesis has only a minor significance when compared to the number of routine craniomaxillofacial procedures which have been performed within the same time. However in patients affected by craniofacial growth disorders distraction osteogenesis has a tremendous significance in combination with other reconstructive procedures within personalised treatment concepts. Transpalatal distraction with or without subsequent orthognathic surgery has proved to be the “working horse” within this group. The combination of computer-assisted surgery and distraction osteogenesis improves planning, surgical transfer, documentation and evaluation of corrective craniomaxillofacial surgery which represents a clear benefit for patients affected by deformities of the craniofacial framework

Contemporary Correction of Dentofacial Anomalies: A Clinical Assessment

Contemporary computer-assisted technologies can support the surgical team in the treatment of patients affected by dentofacial deformities. Based on own experiences of 350 patients that received orthognathic surgery by the same team from 2007 to 2015, this clinical review is intended to give an overview of the results and risks related to the surgical correction of dentofacial anomalies. Different clinical and technological innovations that can contribute to improve the planning and transfer of corrective dentofacial surgery are discussed as well. However, despite the presence of modern technologies, a patient-specific approach and solid craftsmanship remain the key factors in this elective surgery

Role of distraction osteogenesis in craniomaxillofacial surgery

In the field of orthopedic surgery, distraction osteogenesis (DO) is well known for limb lengthening procedures or secondary corrective surgery in the fracture treatment of the extremities. The principle of gradual expansion of bone and surrounding soft tissues as originally described by G.A. Ilizarov is also applicable to the craniofacial skeleton when growth deficiency is present, and the patients affected by craniofacial or dentofacial anomalies may require distraction procedures. The surgical management is comparable. After osteotomy and the mounting of a specific craniomaxillofacial distraction device, active distraction is started after a latency phase of several days, with a distraction rate of up to 1 mm/day until the desired amount of distraction has been achieved. Subsequently, distractors are locked to provide appropriate stability within the distraction zone for callus mineralization during the consolidation phase of 3–6 months, which is followed by a further remodeling of the bony regenerate. After 14 years of clinical application, the role and significance of craniomaxillofacial DO are discussed after reviewing the files of all patients who were treated by craniomaxillofacial distraction procedures

Contemporary Correction of Dentofacial Anomalies: A Clinical Assessment

Contemporary computer-assisted technologies can support the surgical team in the treatment of patients affected by dentofacial deformities. Based on own experiences of 350 patients that received orthognathic surgery by the same team from 2007 to 2015, this clinical review is intended to give an overview of the results and risks related to the surgical correction of dentofacial anomalies. Different clinical and technological innovations that can contribute to improve the planning and transfer of corrective dentofacial surgery are discussed as well. However, despite the presence of modern technologies, a patient-specific approach and solid craftsmanship remain the key factors in this elective surgery

Craniomaxillofacial surgery planning based on 3D models derived from Cone-Beam CT data

Introduction: Individual planning of complex maxillofacial corrections may require 3D models which can be manufactured based on DICOM datasets. The gold standard for image acquisition is still high-resolution multi-slice computed tomography (MSCT). However, appropriate datasets for model fabrication can be acquired by modern Cone-Beam CT (CBCT) devices that have been developed specifically for maxillofacial imaging. The clinical utility of individual models fabricated on the basis of CBCT datasets was assessed. Methods: In five patients affected by different deficiencies of the maxillofacial skeleton, preoperative imaging was performed with ILUMA CBCT. Segmentation of hard tissues was performed manually by thres holding. Corresponding STL datasets were created and exported to an industrial service provider (Alphaform, Munich, Germany) specializing in rapid prototyping, and 3D models were fabricated by the selective laser sintering (SLS) technique. For variance analysis, landmark measurements were performed on both virtual and 3D models. Subsequently, maxillofacial surgery was performed according to the model-based planning. Results: All CBCT-based DICOM datasets could be used for individual model fabrication. Detailed reproduction of individual anatomy was achieved and a topographic survey showed no relevant aberrance between the virtual and real models. The CBCT-based 3D models were therefore used for planning and transfer of different maxillofacial procedures. Conclusions: CBCT-based datasets can be used for the fabrication of surgical 3D models if the correct threshold is set. Preoperative workflow and patient comfort is improved in terms of the fast-track concept by using this in-house imaging technique

Clinical outcome after orbital floor fracture reduction with special regard to patient's satisfaction

Purpose: Primary reconstruction via transconjunctival approach is a standardized treatment option for orbital floor fractures. The aim of this study was to compare the findings of specific ophthalmologic assessment with the patient's complaints after fracture reduction. Methods: A retrospective medical chart analysis was performed on patients who had undergone transconjunctival orbital floor fracture reduction for fracture therapy with resorbable foil (ethisorb sheet or polydioxanone foil). A follow-up assessment including ophthalmological evaluation regarding visual acuity (eye chart projector), binocular visual field screening (Bagolini striated glasses test) and diplopia (cover test, Hess screen test) was conducted. Additionally, a questionnaire was performed to assess patients' satisfaction. Results: A total of 53 patients with a mean follow-up of 23 months (ranging from 11 to 72) after surgical therapy were included. Diplopia was present preoperatively in 23 (43.4%) and reduced in follow-up examination (n = 12, 22.6%). Limitations in ocular motility reduced from 37.7% to 7.5%. The questionnaire about the patient's satisfaction revealed excellent outcomes in relation to the functional and esthetical parameters. Conclusion: Transconjunctival approach is a safe approach for orbital fracture therapy. Postoperative diplopia is nearly never perceptible for the individual and differs to pathologic findings in the ophthalmic assessment. Keywords: Orbital floor fractures, Blow out fractures, Transconjunctival approach, Clinical outcom