Resection Template Research Articles

Evaluation of the accuracy of the resection template and restorations of the bone structures in the mandible area manufactured using the additive technique

The article presents the current possibilities in the field of modeling and manufacturing models of anatomical structures, surgical templates, and implants in terms of planning surgical procedures in the area of ​​the mandible. In the first stage, the 3D reconstruction of the mandible geometry using the 3D-Slicer software was presented. The next step of the process consisted in modeling resection templates and supplementing the loss of the bone structure of the mandible. The last stage consisted of manufacturing models using the additive FDM method from PC-ISO material and performing an accuracy assessment. The models' accuracy using the additive FDM technique is within the tolerance range of +/- 0.2 mm. It is sufficient to use models when planning a procedure.

Лечение сочетанного огнестрельного ранения с дефектом плечевой кости и лучевого нерва (клиническое наблюдение)

Treatment of patients with gunshot bone and soft tissue defects of the extremities requires non-standard approaches and the participation of doctors of various specialties. The application of additive and microsurgical technologies allows one-stage restoration of bone defects and functionally important soft tissue formations. Objective: To demonstrate the possibilities of modern reconstructive-plastic surgery in combination with additive 3D-technology in the treatment of patients with severe gunshot wounds of the extremities. Clinical case: a patient with a combined wound of the chest and upper limb with a primary defect of the humerus and radial nerve. Treatment was based on damage control surgery (DCS) and damage control orthopedic (DCO) tactics. X-ray, computed tomography, and angiography were used for diagnostics and preoperative planning. Based on the CT data, a 3D model of the autograft, resection templates, and a metal structure for osteosynthesis were made. After stabilization of the general condition of the wounded man and elimination of the risk of infectious complications, a one-stage replacement of the radial nerve defect at the level of the middle third of the shoulder with a gastrocnemius nerve autograft was performed; the upper and middle third humeral bone defect was replaced with a free blood-supplied fibula autograft with osteosynthesis using an individual 3D plate with bacteriostatic hydroxyapatite spraying in combination with zinc. А positive anatomical and functional outcome was achieved in the treatment of a patient with a gunshot defect of the humerus and radial nerve. An individual complex approach combined with innovative technologies makes it possible to achieve good anatomical and functional results in the treatment of patients with primary combined limb gunshot defects.

Digital Mapping of a Massive Skull-Base Ameloblastoma with Intracranial Extension, Resection, and Reconstruction Using 3D Templates and Molds: Descriptive Case Report and Review

Radical surgery is the mainstay for the treatment of recurrent ameloblastomas; however, it leads to large, complex defects. In this case report, we present an innovative technique of digitally aided resection and reconstruction. A massive histologically confirmed acanthomatous ameloblastoma of the skull-base was digitally mapped with the help of three-dimensional (3D) computed tomography and a custom resection template was fabricated. Digital resection of the skull-base tumor with intracranial extension was done virtually and the resultant defect was reconstructed to create an anatomical replica of the contralateral unaffected side. The tumor was successfully resected with adequate margins guided by the resection template to avoid injury to adjacent vital structures. Subsequent reconstruction was performed by first adapting polymethyl methacrylate bone cement into a series of custom-made 3D molds. Once set, this bone cement served as a reconstructive implant to bridge the ablative defect. The implant offered a precise fit and was secured to healthy adjacent bone using titanium microplates. We present a 6-month follow-up of the case with satisfactory aesthetic results. 3D printing technology has the potential to revolutionize the arena of craniofacial resection with excellent cosmesis and no donor site morbidity if applied appropriately as described here.

The use of cranial resection templates with 3D virtual planning and PEEK patient-specific implants: A 3 year follow-up

PurposeThe aim of this study was to evaluate the accuracy of resection templates in cranioplasties in order to facilitate a one-stage resection and cranial reconstruction. Patients and methods: In three cases, cranial resections were combined with direct reconstructions using the principles of computer-aided design, manufacturing, and surgery. The precision of the resection template was evaluated through a distance map, comparing the planned and final result. ResultsThe mean absolute difference between the planned and actual reconstructed contour was less than 1.0 mm. After 3 years, no clinical signs of infection or rejection of the implants were present. The computed tomography scans showed no irregularities, and the aesthetic results remained satisfactory. ConclusionOne-stage resection and cranial reconstruction using a resection template, control template, and a prefabricated patient-specific implant of poly(ether-ether-ketone) (PEEK) proved to be a viable and safe method.

EXPERIENCE OF HEAD AND NECK FREE FLAP RECONSTRUCTION IN CHILDREN

From 2015 to 2017, 14 surgical intervention for benign and malignant tumors of mandibular and maxillary regions, soft tissues in the temporal areas and extra organ soft tissue tumors of the head have been performed in the Department of Oncology and Pediatric Surgery of Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology (Moscow). Simultaneous or delayed reconstructions were performed with a bone-muscle flap taken from the crista iliaca, with a fibular flap or a soft tissue radial flap. In all cases, the anastomoses were well-fixed and the flaps viable. The paper presents a clinical case of a 6-year old girl with a central gigantic cell granuloma of the mandibular body. The tumor was resected with a simultaneous reconstruction with a free fibular flap based on stereolythographic resection templates. By the time this paper was written, the duration of the follow-up exceeded 1.5 years. There is no relapse, the free flap is well-fixed and functional, and the child is socially adapted. Based on the radical resection of the primary tumor, preserved innervations of the chin soft tissues, full facial mimics and rapid social adaptation of the child, as well as functional preservation of the jaw and the possibility of oral nutrition, together with the possibility of prosthodontics in the post-operative period, we consider this treatment approach to be optimal for this case. The use of free flaps was highly optimal in all other cases as well, due to their advantages, such as highly radical resection, good functional and esthetic results, rapid social adaptation of children. We believe that wider indications for reconstruction with free flaps are very promising in pediatric practice.

Systematic regional lymph node dissection for upper tract urothelial carcinoma improves patient survival.

Unlike for bladder cancer, the impact of regional lymph node dissection for upper tract urothelial carcinoma is unclear. We explored whether patient survival was influenced by systematic regional lymph node dissection, using resection templates according to the main tumor location, during radical nephroureterectomy for upper tract urothelial carcinoma. The systematic regional lymph node dissection group was defined as cases in which the dissection of nodes and surrounding tissues followed the established template, and the non-systematic regional lymph node dissection group as cases undergoing limited or no lymph node dissection. We performed radical nephroureterectomy on 98 consecutive patients with various stages of upper tract urothelial carcinoma from May 1994 to September 2014 at our institution. Of these, 77 patients with cTanyN0M0 of upper tract urothelial carcinoma undergoing radical nephroureterectomy were grouped into systematic regional lymph node dissection or non-systematic regional lymph node dissection cohorts according to the extent of dissection, and their outcomes compared. Forty-four patients were categorized as systematic regional lymph node dissection and 33 as non-systematic regional lymph node dissection, including 17 with more limited nodal dissection and 16 with no nodal dissection. Five-year recurrence-free survival and cancer-specific survival were significantly higher in the systematic regional lymph node dissection (93% and 94%, respectively) than in the non-systematic regional lymph node dissection group (75% and 77% recurrence-free survival and cancer-specific survival, respectively). Further, 5-year recurrence-free survival and cancer-specific survival of muscle-invasive upper tract urothelial carcinoma (pT2-4) were significantly higher in the systematic regional lymph node dissection (87% and 91%, respectively) than in the non-systematic regional lymph node dissection group (59% and 62%, respectively) (P = 0.0237 and P = 0.0224). Neither recurrence-free survival nor cancer-specific survival was significantly prolonged by systematic dissection in patients with pTis-1 histology. Systematic regional lymph node dissection during radical nephroureterectomy for cTanyN0M0 upper tract urothelial carcinoma patients has a significantly beneficial impact on survival compared with patients undergoing more limited dissection, especially in the cases involving muscle invasion.

Accuracy of virtually 3D planned resection templates in mandibular reconstruction.

Since reconstruction of composite defects in the head and neck region is a challenging and demanding problem for head and neck surgeons, surgical aids have been sought for decades. The purpose of this study was to evaluate the accuracy of prefabricated surgical resection templates used in mandibular segmental resections in comparison to the virtual surgical plan. A prospective study was performed in 11 consecutive patients, with a primary T4 oral squamous cell carcinoma or osteoradionecrosis of the mandible. Preoperatively, a CBCT scan was acquired to delineate the size and extension of tumor invasion; a virtual patient-specific resection template was designed based on this information. Intraoperatively, the resection template was positioned on the mandible and secured using four fixation screws. Postoperatively, a CBCT scan was acquired. This scan was superimposed on the preoperative scan. Positioning of the resection template and inclination of the resection planes were evaluated on the virtual head model. In order to test the interobserver reliability of these new measurement methods, two different observers executed all measurements. The mean shift of the proximal resection templates was 3.76mm (standard deviation [SD] 3.10mm). For the distal resection templates, the mean shift was 3.06mm (SD 1.57mm) with no significant interobserver difference (ICC=0.99). An absolute mean deviation of 8.5° (SD 5.3°) was found for the proximal resection angle and 10.4° (SD 5.0°) for the distal resection angle. Again, no significant interobserver differences were found (ICC=0.98). The resection templates used in this study proved reasonably accurate. Although the concept of virtual surgical planning aids significantly in mandibular reconstruction with microvascular free flaps, further improvement of resection accuracy is necessary for further improvement of reconstruction accuracy.

Post-chemotherapy retroperitoneal lymph node dissection in the management of metastatic testis cancer: the 16-year experience in an Irish setting.

Post-chemotherapy retroperitoneal lymph node dissection (PC-RPLND) is an important tool in the management of advanced germ cell testis cancer, particularly non-seminoma. We present the 16-year experience with PC-RPLND in a single Irish tertiary referral centre, and compare our results to the major speciality centres worldwide. All 78 patients undergoing PC-RPLND for the treatment of metastatic testis cancer between January 1996 and December 2011 were included. Medical records were reviewed and up to date follow-up obtained from primary referral centres, patient's GPs and individual patient interview. The mean age at diagnosis was 28.5±7years. Initial pathology included non-seminoma 62.8%, seminoma 6.4% and combined 19.2%. All patients underwent pre-operative chemotherapy. The resection template utilised was bilateral infra-hilar in 29.5%, unilateralinfra-hilar in 46.2% and supra-hilar in 20.5%. Complete abdominal remission was achieved in all but one patient. Additional procedures were required in 38.5% of patients (n=30). Clavien Dindo grade three or four complications were seen in 8.9%, including five patients who required early reoperation. Histology of RPLND specimen showed mature teratoma (41%) and active cancer (11.5%). Follow-up data were available for 66 patients (85%). Median follow-up was 101 (11-207) months. Nine patients relapsed with median time to relapse 15 (8-60) months. Overall 5-year survival rate was 95.2% (four deaths). In this relatively small series due to small population and low disease incidence, we have shown acceptable peri-operative course, morbidity and oncological outcomes with PC-RPLND compared to major international centres.

External validation of the Heidenreich criteria for patient selection for unilateral or bilateral retroperitoneal lymph node dissection for post-chemotherapy residual masses of testicular cancer

To validate the Heidenreich criteria for patient selection for unilateral retroperitoneal lymph node dissection (RPLND) for residual masses after chemotherapy for nonseminomatous germ cell tumor (NSGCT). For validation, the data of 59 patients who underwent RPLND for residual masses of NSGCT were used. Of these patients, 23 (39 %) qualified for a modified RPLND, the others had an indication for a bilateral dissection. Results from histopathology after RPLND and follow-up data for relapse inside or outside the zone of the resection template were considered for validation. In the study cohort, median age at time of RPLND was 31 years. The 2-year disease-free survival was 90 and 96 % for the bilateral and the unilateral RPLND patients, respectively. Overall, 8 (14 %) relapses were observed after a median follow-up of 54 month. Of these, 6 were outside of the resection field and 2 were in-field. Of the 23 patients with indication for a modified RPLND, 1 patient relapsed in the contralateral testis and 1 inside the modified RPLND template. No relapse was observed outside the modified RPLND field and inside the untouched contralateral RPLND field. The Heidenreich criteria did therefore not misclassify a single patient. The Heidenreich criteria for the selection of candidates for unilateral RPLND for residual masses after chemotherapy allow a highly reliable selection of patients. The application of the Heidenreich criteria can help to reduce comorbidity and invasiveness of RPLND.

Computer-aided resection and endoprosthesis design for the management of malignant bone tumors around the knee: outcomes of 12 cases

BackgroundTo report the outcomes of computer-aided resection and endoprosthesis design for the management of malignant bone tumors around the knee.MethodsComputed tomography (CT) and magnetic resonance imaging (MRI) data were input into computer software to produce three-dimensional (3D) models of the tumor extent. Imaging data was then used to create a template for surgical resection, and development of an individualized combined allogeneic bone/endoprosthesis. Surgical simulations were performed prior to the actual surgery.ResultsThis study included 9 males and 3 females with a mean age of 25.3 years (range, 13 to 40 years). There were 9 tumors in the distal femur and 3 in the proximal tibia. There were no surgical complications. In all cases pathologically confirmed clear surgical margins were obtained. Postoperative radiographs showed the range of tumor resection was in accordance with the preoperative design, and the morphological reconstruction of the bone defect was satisfactory with complete bilateral symmetry. The mean follow-up time was 26.5 months. Two patients died of their disease and the remaining are alive and well without evidence of recurrence. All patients are able to ambulate freely without restrictions. At the last follow-up, the average International Society of Limb Salvage score was 25.8 (range, 18 to 27), and was excellent in 8 cases and good in 4 cases.ConclusionsComputer-aided design and modeling for the surgical management of bone tumors and subsequent limb reconstruction provides accurate tumor removal with the salvage of a maximal amount of unaffected bone and precise endoprosthesis reconstruction.

OP038: Microsurgical reconstruction of maxilla defects after maxillectomy

Background Maxillary defects caused by tumor ablative surgery might lead to deformity of the face and malfunction of mastication, swallowing, phonation and respiration. Microsurgical reconstruction of maxilla is technical challenging and time consuming. The study aims at reporting our experience of maxilla reconstruction using free flaps. Methods We evaluated bony reconstruction after maxillectomy with deep circumflex iliac artery free flap (DCIA) and fibular flap. For fibular flap, preoperative surgical simulation was performed based on CT scans of maxillofacial region and low extremity. Resection template, segmentation template and transfer template were designed and fabricated via rapid prototyping technique. Tumor resection, fibula segmentation and bone graft transfer were performed according to the templates. Results The surgical procedures were all performed successfully. No major post-operative complications were observed. Dental implants were done in selected cases, with satisfactory functional outcome. Conclusion With preoperative surgical simulation, microsurgical reconstruction of maxilla defects with free flap can be accurately performed.

706 EXTERNAL VALIDATION OF THE HEIDENREICH CRITERIA FOR THE SELECTION OF PATIENTS FOR UNILATERAL OR BILATERAL POST CHEMOTHERAPY RETROPERITONEAL LYMPH NODE DISSECTION FOR RESIDUAL MASSES OF TESTICULAR CANCER

You have accessJournal of UrologyPenis/Testis/Urethra: Benign & Malignant Disaese (I)1 Apr 2013706 EXTERNAL VALIDATION OF THE HEIDENREICH CRITERIA FOR THE SELECTION OF PATIENTS FOR UNILATERAL OR BILATERAL POST CHEMOTHERAPY RETROPERITONEAL LYMPH NODE DISSECTION FOR RESIDUAL MASSES OF TESTICULAR CANCER Cedric Vallier, Pierre-Henri Savoie, Jean Robert Delpero, Franck Bladou, Gwenaelle Gravis, Naji Salem, and Jochen Walz Cedric VallierCedric Vallier Marseille, France More articles by this author , Pierre-Henri SavoiePierre-Henri Savoie Marseille, France More articles by this author , Jean Robert DelperoJean Robert Delpero Marseille, France More articles by this author , Franck BladouFranck Bladou Montreal, Canada More articles by this author , Gwenaelle GravisGwenaelle Gravis Marseille, France More articles by this author , Naji SalemNaji Salem Marseille, France More articles by this author , and Jochen WalzJochen Walz Marseille, France, Metropolitan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.264AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The retroperitoneal lymph node dissection (RPLND) for residual masses after chemotherapy for metastatic non seminomatous germ cell tumor (NSGCT) is an invasive procedure. In selected cases, its invasiveness can be reduced by limiting the dissection to a unilateral, modified dissection field instead of a systematic full bilateral dissection. However, the selection of appropriate candidates for a modified RPLND is difficult. Heidenreich et al. proposed 2008 a modified RPLND in cases where the residual mass was in the primary landing zone of testis cancer and the residual mass measured <=5cm in diameter. The aim of our study was to validate these selection criteria. METHODS For validation, 59 patients that underwent retroperitoneal lymph node dissection for residual masses of NSGCT were used. Of these patients, 23 (39%) qualified for a modified RPLND, the others had an indication for a bilateral dissection. Results from histopathology after RPLND and follow-up data for relapse inside or outside the zone of the resection template were considered for validation. RESULTS In the study cohort, median age at time of RPLND was 31 years. The histopathological results showed necrosis in 24 (41%), teratoma in 29 (47%) and vital cancer in 7 (11%) patients. Overall, 8 (14%) relapses were observed after a median follow-up of 54 month. Of these, 6 were outside of the resection field and 2 were in-field. Of the 23 patients with indication for a modified RPLND, 1 patient relapsed in the contralateral testis and 1 inside the modified RPLND template. No relapse was observed outside the modified RPLND field and inside the untouched contralateral PRLND field. The Heidenreich criteria did therefore not misclassify a single patient. The 2 year disease free survival was 90% and 96% for the bilateral and the modified RPLND patients, respectively. Main limitation of the study is the low number of patients and its retrospective nature, a limitation shared with many testicular cancer series. CONCLUSIONS The Heidenreich criteria for the selection of candidates for a modified RPLND for residual masses after chemotherapy for NSGCT allows a highly reliable selection of patients. No patient with a modified RPLND relapsed in the contralateral RPLND field that was left untouched. The application of the Heidenreich criteria can help to significantly reduce comorbidity and invasiveness of RPLND. Ideally validation in larger multicenter series should be performed. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e290 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Cedric Vallier Marseille, France More articles by this author Pierre-Henri Savoie Marseille, France More articles by this author Jean Robert Delpero Marseille, France More articles by this author Franck Bladou Montreal, Canada More articles by this author Gwenaelle Gravis Marseille, France More articles by this author Naji Salem Marseille, France More articles by this author Jochen Walz Marseille, France, Metropolitan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Preformed titanium cranioplasty after resection of skull base meningiomas – A technical note

IntroductionMeningiomas of the fronto-basal skull are difficult to manage as the treatment usually includes extensive resection of the lesion, consecutive reconstruction of the meninges and of the skull. Especially after removal of spheno-orbital and sphenoid-wing meningiomas, the cosmetic result is of utmost importance. In this technical note, we present our institutional approach in the treatment of skull base meningiomas, focussing on the reconstruction of the neurocranium with individually preformed titanium cranioplasty (CRANIOTOP®, CL Instruments, Germany). Case reportTwo female patients (40 years, 64 years) are presented. Both patients presented with skull base lesions suggestive of meningiomas. The preoperative thin-sliced CT scan was processed to generate a 3D-model of the skull. On it, the resection was mapped and following a simulated resection, the cranioplasty was manufactured. Intra-operatively, the titanium plate served as a template for the skull resection and was implanted after microsurgical tumour removal, consecutively. The cosmetic result was excellent. Immediate postoperative CT scan revealed accurate fitting and complete tumour removal. Control Magnetic Resonance Imaging (MRI) within 12 weeks was possible without any artifacts. DiscussionThe comprehensive approach described indicates only one surgical procedure for tumour removal and for reconstruction of the skull. The titanium plate served as an exact template for complete resection of the osseous parts of the tumour. Cosmetic outcome was excellent and control MRI was possible post operatively. ConclusionCRANIOTOP® cranioplasty is a safe and practical tool for reconstruction of the skull after meningioma surgery.

Influence of the distal femoral resection angle on the principal stresses in ceramic total knee components

PurposeA certain failure mode using a newly developed cemented ceramic femoral component in total knee replacement was observed in clinical application, i.e. fracture of the femoral component during intraoperative impaction. This may be caused by unintentional deflection of the saw blades during cutting with consecutive higher resection angle of the distal femur than desired, leading to bending of the femoral component during implantation. A finite-element-analysis was carried out to simulate implantation of the femoral component and to evaluate the influence of distal femur preparation on implant stress. ScopeWe developed and validated a numerical model of the ceramic femoral component including a contact formulation which allowed calculating the principal stresses of the implant during implantation onto the resected femur. The analysis considered different anterior and posterior resection angles with a total of 17 variations. By increasing the femoral resection angle in the finite-element-model it could be shown that a deviation of three degrees from the intended resection angle can cause critical stress amounts during implantation. ConclusionsWhen implanting the ceramic component in total knee arthroplasty, the femoral resection angles should be prepared very precisely, in particular anterior saw blade deflection has to be avoided. The implant manufacturer increased implant safety through an additional resection template. Moreover, the impaction of the ceramic femoral component during cementing was not further recommended by using a hammer.

CT data visualization and simulation— mimics

Computed tomography is unavoidable in OMFS for diagnosis and treatment planning. Cad based medical softwares now are able to reconstruct, visualize, simulate surgical procedures and prepare prosthesis from CT data mimics is a powerful CT data manipulation medical software which also can be used to produce 3D physical models of any part of the human anatomy it can be used for accurate measurement of the defects and template preparation, we have used mimics to visualize bone and soft tissue defects, intra bony lesion and accurate measurement of the extension of the lesion, template for resection, accurate plate adaptation and intra operative guidance and surgical procedure simulation this paper presents our clinical results of surgical cases based on 3D physical models and CT data manipulation with mimics.

Performance of functionally graded implants of polylactides and calcium phosphate/calcium carbonate in an ovine model for computer assisted craniectomy and cranioplasty

Biodegradable functionally graded skull implants on the basis of polylactides and calcium phosphate/calcium carbonate were prepared in an individual mould using a combination of different processing techniques. A geometrically corresponding resection template was designed to enable a craniectomy and cranioplasty with the prepared implant in the same operation. After various preliminary experiments concerning degradation kinetics, pH evolution during degradation, micromorphology, biocompatibility tests in human osteoblast cell cultures and surgery of cadaver heads, a new large-animal model was developed for long-term in vivo studies. In eight 12-months-old sheep, the surgical templates were used to create 4.5 x 5 cm(2) calvarial defects which were then filled with the corresponding degradable implants in the same operation. The animals were sacrificed after 2, 9, 12 and 18 months, and the implants and the surrounding tissues were analysed by computer tomography (CT), macroscopic examination and microscopy. The new animal model proved to be reliable and very suitable for large individual craniectomies and cranioplasties. The formation of new bone from the dural layer of the meninges corresponded well to the degradation of the porous inner layer of the implants whereas the skull contour was stabilised by the compact outer layer over the follow-up period.

Cadaver study: robot-assisted cranial resection and implantation of titanium plates

A processing chain for the prefabrication of individual titanium implants for cranioplasty was developed at the Ruhr-University Bochum. In patients with tumours a simultaneous resection of cranial bone and insertion of the individual implant is desirable. At first resection templates were used for this. New developments aim at a preoperative definition of resection trajectories for surgical robots corresponding to both the planning of the resection and the implant. This study used ovine cadaver skulls for robot resection experiments. The results demonstrate possible applications, limitations and necessary prerequisites in robot assisted cranial surgery.

Resection of skull bone supported by navigation and robotics

From 1993 till 2000, more than 200 individual CAD/CAM (computer-aided design/computer-aided manufacturing) implants have been fabricated for mandibular, midfacial or cranial bony reconstruction based on helical CT-data. Therefore, the TICC-processing-chain (tomography-image processing CAD–CAM) serves as support in reconstruction of skull defects with qualified experiences and surgical knowledge. In a variety of these experimental and clinical applications, modern techniques of computer-assisted surgery, e.g. surgical navigation and robotics, have been used. While using CAD technologies, the planning is already done in virtual reality. Information to support the surgeon in positioning individual resection templates, individual implants and osteotomised bone segments is already produced. To make this information available, the following developments, enumerated below, are the subjects of our actual project. The first step to transfer CT-data into a virtual environment is already solved by the TICC-processing chain. Now, the second step will be performed: the transfer of virtual operation planning data between CAD systems and the real operating room environment. Therefore, interfaces for planning, registration, navigation and robotics are necessary. This includes planning conceptions, software developments and marker systems. Although the single-step resection is possible by producing individual templates corresponding to individual implants, the applications have to be adapted to navigation techniques. First tests with available robotic and navigation systems show the necessity of various setups for different operations, depending on the planned osteotomy and the operation steps. The precision and power transmission depend on the kinematic configuration. Because the planned resection lines depend on the used tools, the technological data of resection tools have to be analysed.

The use of individual surgical templates in computer-assisted surgery

The combination of individual craniofacial CAD/CAM implants and corresponding resection templates makes single-step bone resection and reconstruction possible. The geometric design of these templates should be defined experimentally concerning their precise and stable positioning. Three types of templates with a diameter of approximately 10×8 cm were used in the temporoparietal area of plastic skull models which were scanned by helical CT. The templates' contact to the skull surface differed from a planar circular contact to three defined contact points and a circular linear template-to-bone-contact. Precise and stable positioning of these templates was evaluated, and the resulting resection defects were again scanned by helical CT and were compared to the geometry of the planned defects within the CAD system. In clinical practice the use of the different types of templates was evaluated retrospectively in five patients and by intraoperative verification with a navigation system in another. Resection could be performed as planned in all experimental and clinical applications and the prepared corresponding implants did fit well. The experimental studies demonstrated that templates with a circular linear template-to-bone-contact should be preferred as they can be handled precisely both considering their positioning and their stability.

Craniofacial growth disturbances after frontobasal trauma and craniotomy at the age of 4 years—implications for the timing of CAD/CAM-cranioplasties

The combination of individual craniofacial CAD/CAM implants and corresponding resection templates makes single-step bone resection and reconstruction possible. The geometric design of these templates should be defined experimentally concerning their precise and stable positioning. Three types of templates with a diameter of approximately 10×8 cm were used in the temporoparietal area of plastic skull models which were scanned by helical CT. The templates' contact to the skull surface differed from a planar circular contact to three defined contact points and a circular linear template-to-bone-contact. Precise and stable positioning of these templates was evaluated, and the resulting resection defects were again scanned by helical CT and were compared to the geometry of the planned defects within the CAD system. In clinical practice the use of the different types of templates was evaluated retrospectively in five patients and by intraoperative verification with a navigation system in another. Resection could be performed as planned in all experimental and clinical applications and the prepared corresponding implants did fit well. The experimental studies demonstrated that templates with a circular linear template-to-bone-contact should be preferred as they can be handled precisely both considering their positioning and their stability.