Eine 42-jährige Patientin wurde mit der Diagnose einer primär chronischen Osteomyelitis vorstellig. Seit der Erstmanifestation etwa 9 Monate zuvor waren zahlreiche antibiotische Therapieversuche und Gewebeentnahmen ohne eindeutigen Keimnachweis vorausgegangen. Die Computertomographie zeigte schwere sklerosierende Veränderungen im gesamten rechten horizontalen Unterkieferast mit teilweise osteolytischen Bezirken. Daraufhin erfolgte die Dekortikation mit Gewinnung einer Knochen- und Weichgewebeprobe. Die histologische Begutachtung zeigte gering sklerosierten Knochen mit reaktiver periostaler Knochenneubildung, wie bei einer abgelaufenen chronisch unspezifischen Osteomyelitis. Bei Progression der Beschwerden und Parästhesien im Bereich des N. alveolaris inferior erfolgte im Hinblick auf eine geplante Unterkieferkontinuitätsresektion eine 3-Phasen-Skelettszintigraphie. Neben einer Mehrbelegung im Bereich des Unterkiefers zeigten sich auch intensive Herde an der 1. Rippe rechts, dem Sternum und der Wirbelsäule. Die nachfolgende Magnetresonanztomographie bestätigte bei sämtlichen betroffenen Knochen deutliche Infiltrate, dem Bild einer Osteomyelitis entsprechend. Unter dem Verdacht einer chronisch rekurrierenden multifokalen Osteomyelitis (CRMO) im Erwachsenenalter wurde eine immunsuppressive Therapie mit Diclofenac und Prednisolon eingeleitet, worunter es anfangs zur Vollremission kam. Da es sich bei der CRMO um ein seltenes und in unserem Fachgebiet noch weitgehend unbekanntes Krankheitsbild handelt, ist zu vermuten, dass sie sich in einigen Fällen hinter primär chronischen therapieresistenten Osteomyelitiden verbirgt. Die Problematik liegt in der frühzeitigen Diagnosestellung, da sich der therapeutische Ansatz deutlich von der Therapie der wesentlich häufigeren bakteriellen Osteomyelitis unterscheidet. Im Hinblick darauf ist die skelettszintigraphische Diagnostik therapieresistenter Osteomyelitiden dringend anzuraten.

Article Kalibrierung von Volumendatensätzen aus Spiral-CT-Akquisitionen zur Konturfindung bei individueller Schädelimplantatfertigung was published on January 1, 1998 in the journal Biomedical Engineering / Biomedizinische Technik (volume 43, issue s1).

Article Das TICC-Verfahren (Tomography Imageprocessing CAD CAM) zur individuellen Implantatherstellung was published on January 1, 2000 in the journal Biomedical Engineering / Biomedizinische Technik (volume 45, issue s1).

Patient specific implants milled out of pure titanium showed a good outcome for more than 500 patients in the last decade. The vision of precise reconstruction and new bone generation is combined by the developments of the bioimplant-ruhr. A new animal model shows that the large defect of 4.5 by 5 cm(2) was bridged by new bone within 18 months.

Cones of malignant tumors are commonly known but only a few descriptions of cones in the head and neck area exist - as seen in a 91-year-old patient under our care. Cones of thymic and thyroid cancers are described in the literature. There are no descriptions of cones of head and neck squamous cell carcinomas. Metastases of squamous cell carcinoma in the head and neck area are very aggressive and have a high potential for vascular neogenesis. A vascular cone might be possible by vascular formation or by mechanical intrusion as described elsewhere.

This study was performed to evaluate the surgical strategy in patients with calvarial tumours, in order to design and modify a robot-assisted trepanation system. A total of 75 patients underwent craniectomy for the treatment of calvarial tumours during the 10-year period from 1993 to 2002. The patients' complaints, the size, location and histology of the tumour, and the various cranioplasty techniques used were analysed retrospectively. In a second procedure several craniectomies at typical locations according to the study's results were performed in a laboratory setting using a hexapod robotic tool, constructed at the Helmholtz-Institute, RWTH Aachen University, and plastic model heads. The workflow was documented and the reproducibility and the accuracy of the procedure were registered. A total of 83 surgical procedures were performed on 75 patients. The majority (87%) of lesions treated surgically were located in the frontal, temporal and anterior parts of the parietal region. Histological examination revealed benign lesions in 66% of the patients and dural involvement in 46%. According to these results craniectomies were performed using the robotic system. Mean positioning accuracy of the robotic system while milling was 0.24 mm, with a standard deviation of 0.04 mm, and maximum error under 1 mm. Craniectomies leaving a 1-mm layer of the tabula interna intact to ensure a healthy dura were performed in several regions successfully. The majority of calvarial tumours, requiring surgical treatment in our patients, were located in cosmetically relevant areas in which drilling can be carried out with the robotic trepanation system. Consequently, the surgical approach had to be planned carefully in order to achieve a good cosmetic outcome.

Tumorzapfen in abführenden Venen bei bösartigen Tumoren sind insbesondere von Nierenzellkarzinomen bekannt. Es finden sich jedoch nur wenige Beschreibungen von Tumorzapfen in Halsvenen, wie sie bei einer 91-jährigen Patientin auftraten, die in unserer Behandlung war. Die Ausbildung von Tumorzapfen ist für Thymus- und Schilddrüsenkarzinome beschrieben, doch finden sich keine entsprechenden Hinweise bei Plattenepithelkarzinomen im Kopf-Hals-Gebiet. Metastasen von Plattenepithelkarzinomen der Kopf- und Gesichtshaut weisen eine hohe Aggressivität und eine hohe Tumorangiogeneseneigung auf. Neben einem möglichen Gefäßeinbruch über mechanische Mechanismen, wäre auch ein Einwachsen über eine tumoröse Gefäßneubildung denkbar.

A functionally graded implant was developed to substitute the function of the skull for geometry and for protection of the brain. The implant consists of polylactide/amorphous calcium phosphate as mechanically stable external structure and of polylactide/calcium carbonate as porous internal structure for the ingrowth of bone. For the examination of this protective mechanical function implant fragments were compared with bone fragments of the corresponding calvarium with a 3-point bending test.

OBJECT:Accidental dural tears during craniotomy constitute a possible source of CSF leakage and wound infection. This can turn an elective procedure into a complicated and cost-intensive problem. Only a few studies have addressed the incidence of dural tears, but there have been many studies dealing with various techniques that can be employed to repair dural tears. The present study was carried out to analyze predisposing factors for dural tears during trepanation in order to optimize the design of a robot-assisted trepanation system.PATIENTS:100 patients were analyzed prospectively. An evaluation sheet was designed to document size and location of the lesion and the craniotomy, the geometry and number of burr holes, and the auxiliary tools used during bone flap removal. Furthermore, the suspected histology was noted and anatomical facts, including cranial vault thickness and the presence of hyperostosis frontalis interna, were documented.RESULTS:In 100 craniotomies performed, in the majority of cases (64 %), in order to gain access to intracerebral lesions, 30 dural tears were seen, involving both dural layers in 26 cases. There were 26 tears located under the margins of the craniotomy; the length was 0-3 cm in 18 patients (69 %). Significant predisposing factors were the thickness of the cranial vault and the presence of a hyperostosis frontalis. Furthermore, the location (frontal) and the diagnosis of an extracerebral pathology, including meningiomas, were significant factors for dural tears. Elderly patients and the use of the drill to complete the trepanation were also significant predisposing factors. Dural repair was done using suturing, in most of the cases combined with a free periostal flap. Central dural tears were integrated into the planned dural opening. A vascularized flap or muscle was used in the minority of cases. Postoperative cerebral fluid leakage was seen in two patients, wound infections in three.CONCLUSIONS:Dural tears occurring during craniotomy cannot be prevented, when predisposing factors are taken into account. The absence of brain damage may due to two factors: 1) in elderly patients with hyperostosis, an additional atrophy of the brain is present; 2) extracerebral tumors, with their space-occupying growth, shift the underlying brain away from the calvaria. Considering the design of a robot-assisted trepanation system, the following conclusions seem possible: dural tears cannot be avoided because predisposing factors are overriding. For improved safety, additional, specialized instrumentation is required.

This study of 169 consecutive individually prefabricated CAD/CAM titanium implants for cranioplasty between 1993 and 2000 yields comprehensive data of geometric, surgical, and medical aspects, and answers various questions of quality of life. The scheme for the classification of size and location of the defects is based on the precise CAD data of each implant. CAD/CAM-prefabricated titanium implants are of increased benefit in the neurocranium compared to the craniofacial area, including the forehead and the periorbital rims, which are more problematic with regard to primary fit and cosmetic result. Neurocranial protection and the consecutive improvement of the quality of life are more distinct in this group and come along with the highest benefit for patients with very large defects (>100 cm2 defect area). For the first time, the defect area could be determined so precisely with the CAD implant data and such a high number of extremely large consecutive cranioplasties could be evaluated.

BACKGROUND Bisphosphonates are widely used in the treatment of cancer patients with hypercalcemia and bone metastases or in osteoporosis therapy. Current reports have focused on therapy-resistant osteonecrosis of the jaws as a possible side effect of bisphosphonates. Official German drug committees have recently warned about the possibility of these side effects in the publication organs Deutsches Arzteblatt and Deutsche Apotheker Zeitung. CASE REPORTS So far we have had experience with seven patients showing therapy-resistant osteonecrosis of the mandible under bisphosphonate medication. The presentation of these cases is intended to call attention to this clinically important side effect of bisphosphonate medication.

In the past, rapid prototyping has been used for preoperative planning of surgical operations. Today biocompatible materials are used for soft- and hard-tissue replacement in surgery. This study shows a new application of a laser beam for rapid prototyping. The selective laser melting (SLM) process is used for production of detailed anatomic macro- and micro-structures in 100% dense steel and in titanium.

Introduction: A major goal of research in bone transplantation is the ability to avoid the creation of secondary bone defects. Experiments in minipigs have shown that it is possible to induce heterotopic bone with the aid of recombinant human bone morphogenetic protein-7 (rhBMP-7). We were able to grow an individually customized bone transplant inside the latissimus dorsi muscle of an adult male patient. This was then transplanted to repair an extended mandibular discontinuity defect.

SAMP6 mice exhibit features of skeletal aging including reduced bone mineral density (BMD), diminished rate of bone formation, fewer mesenchymal stem cell (MSC) progenitors of osteoblasts, decreased osteoblasts and increased marrow adipocytes. A decrease in the self-renewal capacity of MSCs may account for the reduced osteoblast number and bone formation. Increased activation, or overexpression, of the transcription factor PPARγ2 in SAMP6 mice may also contribute as features of the SAMP6 skeletal phenotype were reproduced by feeding the PPARγ2 ligand rosiglitazone to normal mice. Genetic mapping studies utilizing F2 progeny of SAMP6 mice mated with either SAMR1 or the related AKR/J strain identified quantitative trait loci (QTLs) for vertebral BMD on chromosomes 2, 7, 11, 13, 16, 18, and X. Transfer of the AKR allele of the chromosome 2 QTL into SAMP6 mice by backcrossing caused a 5.0–5.4% increase in BMD, accounting for ∼50% of the BMD difference between SAMP6 and AKR/J. Studies in Scottish postmenopausal women revealed an association of the X chromosome locus with BMD, thus demonstrating the applicability of QTL mapping information derived from mice to humans. Future genetic and functional studies of SAMP6 mice should therefore provide clues as to why the production of osteoblasts is reduced during aging in mice and humans.

AbstractTitan ist ein etabliertes Knochenersatzmaterial für die Versorgung komplexer Schädeldefekte mittels individuell geplanter CAD/CAM‐Implantate. Zur Verbesserung der durch Patientenkontrollstudien evaluierten thermischen und psychischen Belastungsfaktoren wurde in der vorliegenden Studie ein gradiertes Kompositmaterial aus Polymeren und Calciumphosphat bzw. Calciumcarbonat entwickelt. Biokompatibilitätsuntersuchungen auf Basis des ISO‐Standards 10993‐5 erlaubten zunächst die Auswahl geeigneter Materialien sowie nachfolgend die Feststellung der verbesserten pH‐Charakteristika der Kompositmaterialien gegenüber den reinen Polymeren. Für die geometrisch korrekte Herstellung der Implantate aus Kompositmaterialien wurden zwei unterschiedliche Verarbeitungsmethoden gewählt und kombiniert. Diese Implantate konnten bereits durch in‐vivo Versuche an einem eigens entwickelten Großtiermodell getestet werden und zeigten post mortem bei einem Nachbeobachtungszeitraum von zwei Monaten keine histologischen Reaktionen außerhalb der Norm und eine beginnende Knochenbildung. Klinisch ergaben sich bei den lebenden Schafen auch nach einem Zeitraum von bisher 11 Monaten keinerlei Komplikationen.

BACKGROUND:A major goal of research in bone transplantation is the ability to avoid creation of secondary bone defects. We aimed to repair an extended mandibular discontinuity defect by growth of a custom bone transplant inside the latissimus dorsi muscle of an adult male patient.METHODS:Three-dimensional computed tomography (CT) scanning and computer-aided design techniques were used to produce an ideal virtual replacement for the mandibular defect. These data were used to create a titanium mesh cage that was filled with bone mineral blocks and infiltrated with 7 mg recombinant human bone morphogenetic protein 7 and 20 mL of the patient's bone marrow. Thus prepared, the transplant was implanted into the latissimus dorsi muscle and 7 weeks later transplanted as a free bone-muscle flap to repair the mandibular defect.FINDINGS:In-vivo skeletal scintigraphy showed bone remodelling and mineralisation inside the mandibular transplant both before and after transplantation. CT provided radiological evidence of new bone formation. Postoperatively, the patient had an improved degree of mastication and was satisfied with the aesthetic outcome of the procedure.INTERPRETATION:Heterotopic bone induction to form a mandibular replacement inside the latissimus dorsi muscle in a human being is possible. This technique allows for a lower operative burden compared with conventional techniques by avoiding creation of a secondary bone defect. It also provides a good three-dimensional outcome.

According to the desire of single-step skull bone resection and reconstruction the acquired CT data were not only used for the design of the individual implant but also for a robot-guided bone resection in an animal cadaver model. The results of three robot skull bone resections during 4 years showed a perspicuously improved precision combined with a dramatically reduced set-up time. As the evaluation of 166 patients with titanium skull implants showed thermal and psychic stress factors, a biodegradable composite material from polyesters, calcium phosphate and calcium carbonate for guided bone regeneration was developed. Skull implants made of this new bone substitution material showed promising results in animal experiments over a follow-up period from 2 to 11 months so far.

The aim of this study was the development of a processing pathway for manufacturing of biodegradable skull implants with individual geometry. The implants on the basis of polylactide and calcium phosphate/calcium carbonate were prepared by a combination of hot pressing and gas foaming. On the inside, the implant consists of a macroporous and faster degradable material (poly(d,l-lactide)+CaCO3) to allow the ingrowth of bone cells. The pore size is in the range of 200–400 μm. On the outside, the implant consists of a compact and slower biodegradable material (poly(l-lactide) and calcium phosphate) to ensure mechanical stability and protection. To overcome problems like inflammatory reactions caused by acidic degradation products of polylactide, the polyester was combined with basic filling materials (calcium salts). The filler neutralises the lactic acid produced during polymer degradation and increases the bioactivity of the material. The stabilised pH was demonstrated by long-term in vitro pH studies. Over a time period of 250 d in demineralised water, the pH was in the physiological range. The in vitro biocompatibility was shown by cell cultures with human osteoblasts. A good proliferation of the cells was observed over the whole test period of 4 weeks.

“Bochum Skull Implants” have been used in more than 300 patients so far. They are designed using reconstructed computed tomography (CT) data and produced out of pure titanium in a milling process. This report describes the clinical experience with the patients treated between 1994 and 2000. The defect region and its size as well as the outcome of the patients are analyzed. Considering the negative selection of patients, the advantages of the described procedure are impressive. The high precision and the easy handling of these implants make them useful, especially in complicated applications with very large defects, multiple previous operations and sometimes additional irradiations.