Development of a brain simulator for intracranial targeting: Technical note.

Learning and enhancing of manual skills in the field of neurosurgery requires an intensive training which can be maintained by using virtual reality (VR)-based or physical model (PM)-based simulators. However, both simulator types are limited to one specific intracranial procedure, e.g. the application of an external ventricular drainage (EVD), and they do not provide any accuracy verification. We present a brain simulator which consists of a 3D human skull model having five electroconductive balls in its interior. The installed balls represent intracranial target points providing various accuracy problems in neuronavigation. They are electrically contacted to lamps getting an optical signal by touching them with a current-carrying target tool. The simulator fulfills two requirements: First, it can prove the accuracy of navigation systems and algorithms. Second, it allows becoming familiar with a navigation system's application in an ex vivo setting. It could be a helpful device in neurosurgical skills labs.

One-step CAD/CAM titanium cranioplasty after drilling template-assisted resection of intraosseous skull base meningioma: technical note.

INTRODUCTION: Cranial defects following intra-osseous tumor removal may be large and require adequate reconstruction. CAD/CAM implants have been used for years to achieve an optimal cosmetic result. The disadvantage is that such implants require a second surgery. A preoperative virtual planning of resection margins and the simultaneously fabrication of the cranioplasty could be a possibility to subsume the steps tumor resection and cosmetic restoration to a single procedure. METHODS: We present two cases of patients with complex intra-osseous spheno-orbital meningioma. Tumor resection was performed with the help of a drilling template in form of a frame. The template also served as a negative for the computer-designed cranioplasty. The devices were manufactured by DMD GmbH - Digital Medical Design/DDI-Group, Dortmund, Germany. DISCUSSION: The usage of the template was highly practicable. Small adjustments in bone removal were necessary to achieve an optimal fitting of the implant. The 6-month follow-up showed for one patient a good and for one a satisfactory cosmetic result. No second surgery was necessary. CONCLUSIONS: Drilling template application could contribute to challenging cases of large fronto-basal meningiomas with the aim of minimizing operation time and achieving a good esthetic outcome.

[Cadaver study: robot-assisted cranial resection and implantation of titanium plates]. / Kadaverstudie: roboterunterstützte Schädelresektion und Versorgung mit Titanimplantaten.

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.

[A graded composite material for use in the area of the cranial and facial skull]. / Ein gradierter Kompositwerkstoff für den Einsatz im Bereich des Hirn- und Gesichtsschädels.

For the reconstruction of complex skull defects with individual prefabricated CAD/CAM-implants titanium is well established as bone substitution material. The aim of our studies was to optimize a composite material from polyesters and calcium phosphate. Therefore two different operating procedures (hot pressing and gas-flushing) were combined. As a result the graded composition and porosity of the implants allow a spatial guided degradation progress and cell ingrowth. First biocompatibility tests in vitro with primary human osteoblasts showed a much better pH-characteristic and a better biocompatibility of the composites in comparison with the pure polymers. Degradation experiments in vitro confirmed the different expected degradation rates of the composite materials. As a next step in vivo experiments in ovine skulls are in progress.

[Reconstruction of the frontal bone with individual titanium implants after surgical therapy of osteomyelitis of the frontal bone]. / Rekonstruktion des Os frontale mit individuellen Titanimplantaten nach chirurgischer Therapie der Stirnbeinosteomyelitis.

Individually prefabricated titanium implants enable the reconstruction of the frontal bone after surgical therapy of osteomyelitis without compromising mechanical stability or aesthetic results. Primarily the infected bone tissue is removed. Helical computed tomographic systems are used for the aquisition of patient data. After being transmitted to a computer aided design system (CAD-system) this data is used for construction of the implant geometry using freeform-surfaces. The outer surface contour is derived from the contours of the bone defect. The completed computer-based implant design is finally transformed into control data to run the milling machine which produces the implant from a block of titanium. Modern industrial CAD/CAM-technology allows standardized prefabrication using data from CT-scans. The precision of all implants was predictable and duration of the reconstructive procedure could be reduced. During postoperative follow-up (5-24 months) no loss of implant or recurrence of the osteomyelitis could be observed.

[Alternative bone replacement substances for preoperative design of individual CAD/CAM skull implants]. / Alternative Knochenersatzmaterialien zur präoperativen Fertigung individueller CAD/CAM-Schädelimplantate.

BACKGROUND: The preoperative manufacturing of individual skull implants using computer aided design (CAD) and computer aided manufacturing (CAM) is based on the use of titanium, although the use of other materials is also potentially possible. THE USE OF OTHER MATERIALS: The use of poly-(D,L-lactide) (PDLLA) as an implant material was investigated using an adult, formalin fixed sheep's head with a complex frontolateral defect. A standard individual titanium implant as well as a resection template made of aluminium were milled in order to allow bone resection and reconstruction within one operation. A mould was made of Teflon for the fabrication of the PDLLA implant using carbon dioxide at high pressure. This procedure allowed a critical comparison to be made of both implant materials and showed that the production of a biodegradable PDLLA implant is possible. At present the titanium implant is superior to the PDLLA implant, as PDLLA settled with slightly larger dimensions than the mould, although the structure itself was exact. DISCUSSION: The goal of the present research is the fabrication of a functionally graded material made of polylactide, polyglycolide, calcium phosphate and osteoinductive proteins using existing technology, which will meet all of the requirements for stability, resorption kinetics, biocompatibility, radiotranslucence and osteogenic potency of an ideal implant material.

[Combined interventions in primary management of patients with lip-jaw-palatal clefts]. / Kombinationseingriffe in der primären Versorgung von Patienten mit Lippen-Kiefer-Gaumen-Spalten.

BACKGROUND: The continuing improvement in the care and treatment of cleft lip and palate in infants raises the question of whether the total number of surgical steps in primary cleft repair could be reduced without additional risk to the patients. A total of 108 patients, born between 1985 and 1997 with complete cleft lip and palate, were evaluated in this study. The patients were treated at the Department of Oral and Maxillofacial Surgery of the Ruhr-University Bochum with 106 "combined" (group A, n = 54) and 141 "separated" (group B, n = 54) operations. The newer "combined" strategy, with several surgical steps conducted in one operation, was compared with the older "separated" procedures by analysis of various peri- and postoperative parameters. RESULTS: Patient groups A and B were differentiated by the following operation related data: 1st primary operation: age: 5.8 vs 4.6 months (P < 0.01), weight: 6.8 vs 6.5 kg (P = 0.2); 2nd primary operation: age: 13.9 vs 9.6 months (P < 0.01), weight: 9.2 vs 8.5 kg (P = 0.16); total intraoperative blood loss: 122 vs 147 ml, (P = 0.16); total time during which the patient was operated: 4.9 vs 5.4 h (P = 0.17); peri- and postoperative rate of complications: 14 vs 15% (P = 0.87) for the first primary and .27 vs 28% (P = 0.96) for the second primary operation; rate of wound dehiscence: 18 vs 13% (P = 0.66); total time hospitalized: 27 vs 34 days (P = 0.01). DISCUSSION: The "combined" surgical procedures reduced the number of surgical interventions under general anaesthesia and led to a significant reduction of the overall blood loss and hospitalisation. A slightly higher age at the first intervention made the minor increase in blood loss tolerable. The rate of perioperative complications showed no increase.

[Management of craniofacial bone defects with individually prefabricated titanium implants. Follow-up and evaluation of 78 patients with 78 titanium implants 1994-1998]. / Versorgung kraniofazialer Knochendefekte mit individuell vorgefertigten Titanimplantaten. Nachuntersuchung und Auswertung von 76 Patienten mit 78 Titanimplantaten der Jahre 1994-1998.

STUDY: From 1994 to 1998, 78 prefabricated titanium implants were used for the reconstruction of large and complex cranial and craniofacial defects in 76 patients at 19 European centres. After a mean follow-up of 8 months, a clinical and radiological examination was used to determine the results of the reconstruction and the patients' satisfaction. Using a standardized questionnaire patients were also able to comment, subjectively, on improvements or alterations after the insertion of the implant. RESULTS: Two implants were removed after an early infectious complication and in a another two cases the implants were removed in order to obtain a tissue sample for histological examination. All other patients showed constant good to excellent clinical and radiological findings with high patient satisfaction. DISCUSSION: The use of titanium fulfils the highest demands of biocompatibility while at the same time allowing the possibility of an oncological examination using suitable turbo-spinecho-sequences in MRI.

Synthesis of CAD/CAM, robotics and biomaterial implant fabrication: single-step reconstruction in computer-aided frontotemporal bone resection.

The preoperative manufacturing of individual skull implants, developed by an interdisciplinary research group at Ruhr-University Bochum, is based on the use of titanium as the most common material for implants at present. Using the existing technology for materials that can be milled or moulded, customized implants may be manufactured as well. The goal of the study was to examine biodegradable materials and to evaluate the practicability of intraoperative instrument navigation and robotics. Data acquisition of an adult sheep's head was performed with helical computer tomography (CT). The data were transferred onto a computer aided design/computer aided manufacturing system (CAD/CAM system), and two complex defects in the frontotemporal skull were designed. Standard individual titanium implants were milled for both of the defects. Additionally, for one of the defects a resection template, as well as a mould for the biodegradable poly(D,L-lactide) (PDLLA) implant, were fabricated by the CAD/CAM system. A surgeon carried out the first bone resection (#1) for the prefabricated titanium implant using the resection template and an oscillating saw. The robot system Stäubli RX90CR, modified for clinical use, carried out the other resection (#2). Both titanium implants and the PDLLA implant were inserted in their respective defects to compare the precision of their fit. A critical comparison of both implant materials and both resection types shows that fabrication of a PDLLA implant and robot resection are already possible. At present, the titanium implant and resection using a template are more convincing due to the higher precision and practicability.

[Mandibular involvement in chronic recurrent multifocal osteomyelitis (CRMO) in adulthood]. / Mandibulabeteiligung bei der chronisch rekurrierenden multifokalen Osteomyelitis (CRMO) im Erwachsenenalter.

A 42-year-old patient was admitted to our clinic with the diagnosis of primary chronic osteomyelitis of the mandible. Since the initial manifestation, approximately 9 months earlier, the patient had undergone numerous antibiotic treatment trials. Various tissue specimens exhibited no microbial growth. Computer tomography demonstrated severe sclerotic changes with partly osteolytic areas in the complete right horizontal ramus of the mandible. Decortication was carried out and both soft and hard tissue specimens were taken. Histological assessment revealed slightly sclerotic bone with reactive periosteal bone production, as in chronic non-specific osteomyelitis. Because of progressive pain and paresthesia, a 3-phase skeletal scanning was performed before the planned resection. In addition to an intensive labeling in the right mandible, further intensive lesions were found at the first right rib, the sternum, and the vertebral column. The subsequent magnetic resonance tomography confirmed the infiltration, as seen in osteomyelitis, in all these areas. Under the assumption of chronic recurrent multifocal osteomyelitis (CRMO), an immunosuppressive therapy with diclofenac and prednisolone was started, which at first brought about complete remission. As CRMO is very rare in our specialty, it might be suspected that it is the cause of some cases of primary therapy-resistant osteomyelitis. The importance of early diagnosis must be underlined, because therapy differs fundamentally from that of the more common bacterial osteomyelitis. A bone scan is therefore of great value in the diagnostic scheme of therapy-resistant osteomyelitis.