Martin Ruecker

Pre-operative planning for mandibular reconstruction - A full digital planning workflow resulting in a patient specific reconstruction

ObjectivesReconstruction of large mandiblular defects following ablative oncologic surgery could be done by using vascularized bone transfer or, more often, primarily with simultaneous or delayed bone grafting, using load bearing reconstruction plates. Bending of these reconstruction plates is typically directed along the outer contour of the original mandible. Simultaneously or in a second operation vascularized or non-vascularized bone is fixed to the reconstruction plate. However, the prosthodontic-driven backward planning to ease bony reconstruction of the mandible in terms of dental rehabilitation using implant-retained overdentures might be an eligible solution. The purpose of this work was to develop, establish and clinically evaluate a novel 3D planning procedure for mandibular reconstruction.Materials and methodsThree patients with tumors involving the mandible, which included squamous cell carcinoma in the floor of the mouth and keratocystic odontogenic tumor, were treated surgically by hemimandibulectomy.ResultsIn primary alloplastic mandible reconstruction, shape and size of the reconstruction plate could be predefined and prebent prior to surgery.Clinical relevanceThis study provides modern treatment strategies for mandibular reconstruction.

Advances and innovations in computer-assisted head and neck oncologic surgery.

Abstract Over the past years, computer-assisted surgery has gained more importance in craniomaxillofacial surgery, especially in primary and secondary treatment of head and neck malignancies. The basis for oncologic treatment of the head and neck region requires detailed planning using computed tomography, cone-beam computed tomography, or magnetic resonance imaging in combination with computer-assisted, infrared-based navigation system. These techniques allow a preplanned image-guided path to the tumor region for taking biopsies, resection, or reconstruction. The aim of this work was to show the advances and technical benefits for tumor surgery in a daily clinical routine from the view of the craniomaxillofacial surgeon. The target of our working group was to develop and clinically evaluate a novel three-dimensional planning and navigation software solution for treatment of craniofacial tumors. This work was carried out on 5 categories for oncologic surgical procedures in which computer-assisted surgery was applied from 2005 to 2011: preplanned trajectorial-guided tumor biopsy, intraoperative image–controlled tumor resection, tumor mapping, reconstruction after tumor surgery (true to original), and oral rehabilitation (backward planning). Successful preoperative planning, import of image data suitable for navigation, and intraoperative precise infrared-based navigation were obtained for all 5 categories without any complications. Image-guided navigation technique for head and neck oncologic surgery provides a precise, safe surgical method with real-time excellent anatomic orientation. Regarding the advantages of computer-assisted surgery, this technique will play a major part in craniofacial reconstructive surgery and will address widespread general methodologic solutions that are of great interest in multidisciplinary oncologic treatment.

Complex Midfacial Reconstruction: A Combined Technique of Computer-Assisted Surgery and Microvascular Tissue Transfer

The human midface is a complex anatomic region. The maxilla is the structural support between the skull base and the occlusal plane, resisting the forces of mastication, anchoring the dentition, separating the oral and nasal cavities, supporting the globe, and supporting the face and its mimetic musculature. 1 The midface region dominates our outward appearance, which is unique to each individual, and its esthetic restoration after loss of the maxilla is of major importance for quality of life. Destruction of the midface may result from trauma, infectious or malignant

The Hannover experience: Surgical treatment of tongue cancer - A clinical retrospective evaluation over a 30 years period

ObjectivesIn this retrospective study, we present a clinical review of our experience with tongue cancer in order to obtain valid criteria for therapeutic decision-making.Materials and methodsBetween 1980 and 2009, a total of 341 patients with squamous cell carcinoma of the tongue were treated at our Department. The average follow-up was 5.2 years. 309 patients received surgical treatment, which was combined in nearly 10% with neoadjuvant and in nearly 20% with postoperative radio(chemo)therapy. 32 patients were excluded from surgery and received primary radiation.ResultsLocal and regional failure occurred in 23.9% and 20.4%, leading to a total failure rate of 37.2% after an average duration of 1,6 years. N-Status, extracapsular spread and clear margins were identified as the dominant factors for survival, which was calculated with 54.5% after 5 years.ConclusionsWe recommend categorical bilateral neck dissection in order to reliably remove occult lymph node metastases. Adjuvant treatment modalities should be applied more frequently in controlled clinical trials and should generally be implemented in cases with unclear margins and lymphatic spread.Clinical relevanceThis study provides new treatment strategies for primary tumour disease and for tumour recurrence.

Forty Sandwich Osteotomies in Atrophic Mandibles: A Retrospective Study

PURPOSE The aim of the present retrospective study was to assess the suitability of segmental mandibular sandwich osteotomy combined with an interpositional autograft to meet the dimensional requirements of preimplant bone augmentation in cases of a severely atrophic mandible. PATIENTS AND METHODS A total of 27 consecutive patients (6 men and 21 women) were included in the present study. The amount of bone gain was calculated using digital volume tomography before surgery and 3 months after bone augmentation. RESULTS The postoperative course was uneventful for 18 patients. Temporary sensory disturbances were observed in 6 patients, with complete recovery after 3 to 12 weeks. Dehiscence of soft tissue closure occurred in 3 patients. The mean vertical gain was 3.41 mm (range 0.3 to 12). The mean horizontal gain was 3.08 mm (range 0.2 to 8.5). A total of 88 implants were placed in 40 surgical sites at 12 weeks after bone reconstruction. CONCLUSION Segmental mandibular sandwich osteotomy is a suitable augmentation procedure in the mandible for the atrophic alveolar ridge and provides adequate height and transversal bone augmentation.

Modern surgical management of tongue carcinoma - A clinical retrospective research over a 12 years period

ObjectivesIn this retrospective study, we present a clinical review of our experience with tongue cancer in order to obtain valid criteria for therapeutic decision-making.Materials and methodsBetween August 1999 and June 2011, a total of 398 patients with squamous cell carcinoma of the tongue were treated at the Department of Oral and Maxillofacial Surgery, King Edward Medical University Lahore Pakistan. Data concerning patient characteristics, clinical and pathologic tumour characteristics and treatment strategies and their results were obtained from a retrospective review of medical records. The average follow-up was 4.6 years. Statistical analysis for survival was calculated by the method of Kaplan and Meier.ResultsThere were 398 total patients. The mean age at diagnosis was 49.5 years,. 224 (56.3%) were male and 174 (43.7%) female (male/female ratio = 1.3:1).332/398 patients received surgical treatment, whereas 66 patients were excluded from surgical treatment and received primary radio (chemo) therapy after biopsy. Tongue carcinoma patients treated by non surgical treatment modalities had 5 years survival rate of 45.5% and patients with surgical intervention had survival rate of 96.1%.ConclusionsWe recommend categorical bilateral neck dissection in order to reliably remove occult lymph node metastases. Adjuvant treatment modalities should be applied more frequently in controlled clinical trials and should generally be implemented in cases with unclear margins and lymphatic spread.Clinical relevanceThis study provides modern treatment strategies for the tongue carcinoma.

Virtual 3D tumor marking-exact intraoperative coordinate mapping improve post-operative radiotherapy

The quality of the interdisciplinary interface in oncological treatment between surgery, pathology and radiotherapy is mainly dependent on reliable anatomical three-dimensional (3D) allocation of specimen and their context sensitive interpretation which defines further treatment protocols. Computer-assisted preoperative planning (CAPP) allows for outlining macroscopical tumor size and margins. A new technique facilitates the 3D virtual marking and mapping of frozen sections and resection margins or important surgical intraoperative information. These data could be stored in DICOM format (Digital Imaging and Communication in Medicine) in terms of augmented reality and transferred to communicate patients specific tumor information (invasion to vessels and nerves, non-resectable tumor) to oncologists, radiotherapists and pathologists.

Referencing of markerless CT data sets with cone beam subvolume including registration markers to ease computer-assisted surgery - a clinical and technical research.

As a prerequisite in navigation‐assisted surgery, a three‐dimensional image data set with registration marker is necessary. Often patients are presented, not being aware of facing a computer‐assisted surgical intervention (CAS), with an already performed computed tomography (CT) data set without marker. The aim of this study was to evaluate the accuracy of a new method which allows performing CAS by enhancing the initial markerless data set with a marked subvolume gained by cone beam (CBCT) scan.

Development and Demonstration of a Novel Computer Planning Solution for Predefined Correction of Enophthalmos in Anophthalmic Patients Using Prebended 3D Titanium-Meshes—A Technical Note

Ablative surgery of the orbit is often associated with dramatic changes in facial geometry. Surgical intervention is often necessary to correct the functional and esthetic appearance in those patients who are anophthalmic, having an intact eyelid appearance and an orbital prosthesis. The outcome of the surgical correction depends on the shape of the orbital implants and their adequate placement. In the case of comparatively small rearrangements, the effect of implants on soft tissues can be estimated by surgeons on the basis of their experience. However, large deformities in complex cases (including large deformation of soft tissue or asymmetry) can be hardly predicted on the basis of simple empirical considerations. The purpose of the present technical note was to describe a new procedure of inverse design of customized orbital titanium meshes. To demonstrate this procedure, an anophthalmic patient with superior sulcus deformity and enophthalmos was enrolled. The volume and structure of the extraocular muscles, soft tissue, and bony structure of the orbital walls were examined using high-resolution multislice computed tomography. Next, a geometric model of the patients anatomy was generated from the tomography data. Afterward, the orbital prosthesis was virtually relocated to a new position. Then, the desired correction of the particular soft tissue regions was performed using virtual sculpturing tools. Next, the deformation of the soft tissues and initial prosthesis boundaries were computed from the predefined displacements of the relocated tissue regions with the help of the Finite Element Method. The differential volume between the initial and designated position of the orbital prosthesis yielded the preferred implant shape required to effect the desired correction of soft tissue. During surgery, the preplanned position of the customized titanium meshes was guided using a navigation system. Although the inverse design of custom-tailored titanium meshes for precision treatment of severe enophthalmos in anophthalmic patients appears to be a promising approach, it has rarely been applied in the past because of the technological complexity and additional time required. With the present study, we have launched a series of clinical evaluations of this novel method. To date, scientific evidence and trials showing a predictable simulation using an inverse finite element approach in the correction of severe enophthalmos in anophthalmic patients with computer-assisted fabricated individual titanium meshes for reconstruction of orbital walls have been rare.

Designing the ideal model for assessment of wound contamination after gunshot injuries: a comparative experimental study

BackgroundModern high-velocity projectiles produce temporary cavities and can thus cause extensive tissue destruction along the bullet path. It is still unclear whether gelatin blocks, which are used as a well-accepted tissue simulant, allow the effects of projectiles to be adequately investigated and how these effects are influenced by caliber size.MethodBarium titanate particles were distributed throughout a test chamber for an assessment of wound contamination. We fired .22-caliber Magnum bullets first into gelatin blocks and then into porcine hind limbs placed behind the chamber. Two other types of bullets (.222-caliber bullets and 6.5 × 57 mm cartridges) were then shot into porcine hind limbs. Permanent and temporary wound cavities as well as the spatial distribution of barium titanate particles in relation to the bullet path were evaluated radiologically.ResultsA comparison of the gelatin blocks and hind limbs showed significant differences (p < 0.05) in the mean results for all parameters. There were significant differences between the bullets of different calibers in the depth to which barium titanate particles penetrated the porcine hind limbs. Almost no particles, however, were found at a penetration depth of 10 cm or more. By contrast, gas cavities were detected along the entire bullet path.ConclusionGelatin is only of limited value for evaluating the path of high-velocity projectiles and the contamination of wounds by exogenous particles. There is a direct relationship between the presence of gas cavities in the tissue along the bullet path and caliber size. These cavities, however, are only mildly contaminated by exogenous particles.