Analysis of surgical management of calvarial tumours and first results of a newly designed robotic trepanation system.

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.

[Necrosis of the jaws under bisphosphonate therapy]. / Nekrosen der Kieferknochen unter Bisphosphonattherapie.

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. So far we have experience with 12 patients showing therapy-resistant osteonecrosis of the mandible under bisphosphonate medication, three of whom received oral bisphosphonates for osteoporosis treatment. Presentation of these three cases provides more information on this clinically important side effect of oral bisphosphonate medication, also in osteoporosis therapy.

[Rare entity of a macroscopically visible tumor cone of squamous cell carcinoma in the greater veins of the head and neck]. / Seltene Entität eines makroskopisch sichtbaren Tumorzapfens eines Plattenepithelkarzinoms in den grossen Kopf-Hals-Venen.

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.

Accidental dural tears occurring during supratentorial craniotomy -- a prospective analysis of predisposing factors in 100 patients.

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.

[Osteonecrosis of the jaws as a possible adverse effect of the use of bisphosphonates]. / Kieferknochennekrosen als mögliche unerwünschte Wirkung von Bisphosphonaten.

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.

Growth and transplantation of a custom vascularised bone graft in a man.

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.

The radial forearm flap as a carrier for the osteocutaneous fibula graft in mandibular reconstruction.

According to the concept of a free flap carrier we transferred an osteocutaneous fibula graft after microanastomosis to a pedicled radial forearm flap for reconstruction of the lower face in a patient with a total occlusion of the left and a subtotal occlusion of the right common carotid artery. The fibula was osteotomized in three segments to form the new mandible, and the skin paddle was placed extraorally. An external fixation device was connected to the radial bone, and a halo frame was fixed to the skull, and the forearm was thus stabilized rigidly in a suitable position. After 2 weeks, serial occlusion of the pedicle was begun twice daily. Blood flow and haemoglobin oxygenation of the skin paddle were measured by laser Doppler flowmetry and photometry. At the 14th day of ischaemic preconditioning, the flap could tolerate 3h of occlusion. Then the carrier vessels and the forearm flap were excised. The flap survived completely based on neovascularization from the recipient site.

Stability of bone grafting and placement of implants in the severely atrophic maxilla.

A severely atrophic maxilla can be restored by bone grafts to allow the insertion of implants. We present 30 consecutive patients treated with autogenous inlay and onlay bone grafts from the iliac crest to the floor of the maxillary sinus and the alveolar crest. A total of 200 implants were inserted 4-6 months after bone grafting. A mean vertical increase in bone thickness of 14mm was achieved. After a mean bone loss of 1.3mm during the first year after bone grafting only minimal resorption was observed during the second and third year. Seven implants failed to integrate and a further four implants were lost during follow-up.

[Indications for primary surgical therapy of vascular abnormalities in infancy]. / Indikationen zur primären operativen Therapie von Gefässanomalien im Säuglingsalter.

LASER THERAPY: Since the introduction of laser therapy for treatment of hemangiomas and vascular malformations, primary surgical therapy has gradually lost importance. Particularly hemangiomas, but also venous malformations and lymphangiomas, are nowadays primarily treated by different types of lasers. Especially the Nd:YAG laser with a percutaneous or transcutaneous application technique often leads to satisfying results. SURGICAL THERAPY: Surgical therapy is mostly used secondarily in late childhood or in adults after several laser applications for excision of residual scars or other corrective procedures. Despite these improvements in laser therapy, there is still an indication for primary surgical treatment in subcutaneous vascular malformations and in rapidly growing hemangiomas after unsuccessful laser therapy. Even in large vascular anomalies, safe excision with only a little blood loss is possible if the tumors are encapsulated. CASE REPORTS: In this paper we want to point out the necessity of primary surgery in three children in whom complications such as loss of sight, facial nerve palsy, and a lethal outcome due to massive hemorrhage in a cystic lymphangioma could be avoided.

[Osseous processes of the skull--analysis of requirements for robot-assisted surgery]. / Ossäre Prozesse des Schädels-Anforderungsanalyse für robotergestütztes Operieren.

To design a roboter-assisted trepanation setting of the cranium, an evaluation was done to classify patients with osseous lesions according to pathologies, dimensions and localisations. Emphasis was laid on dimensions and localisation of the pathology to gain information on future configurations of work spaces for robotics in the neurosurgical operation room. All patients with surgery of osseous lesions of the cranium in the years 1993-2001 were evaluated retrospectively. Localisations, dimensions of trepanation and histologic results were evaluated.

[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.

Computer-assisted prefabrication of individual craniofacial implants.

Historically, reconstruction of the skull with intraoperatively modeled implants has been restricted severely by limitations in implant material, unpredictable aesthetic results, prolonged OR time, and indirect techniques that cause decreased precision and increased expense. This article discusses modern computer-aided design and manufacturing systems that allow for direct preoperative fabrication of implants out of pure titanium with a variety of enhanced construction details. Between 1997 and 1999, 135 cranial and craniofacial reconstructions with defects measuring up to 22 cm were performed using this technique at 25 health care centers in Europe. The results obtained in these patients were predictable and constant and demonstrated dramatically reduced OR times.

[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.

[Individualized facial protection after fracture management of the nasal bone and zygomatic arch in professional soccer players]. / Individueller Gesichtsschutz nach Frakturversorgung am Nasenbein und Jochbogen bei Profifussballern.

BACKGROUND: The treatment of sport accidents in professional athletes requires special treatment modalities, especially concerning quick rehabilitation. CASE REPORT: As early as 5 days after treatment of a nasal bone fracture under local anesthesia on an outpatient basis, an individual nasal shield out of silicone and acrylate could be manufactured from a facial impression for a professional soccer player. This shield enabled unlimited participation in the ensuing premier league matches 7 and 14 days after the accident. The same treatment was performed for another team member after closed reposition of a zygomatic arch fracture. Treatment modalities and manufacturing of the facial protection masks in these two cases are presented as examples.

[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.

Purulent pansinusitis, orbital cellulitis and rhinogenic intracranial complications.

OBJECTIVES: Acute pansinusitis is rarely seen in the maxillofacial surgery field, but often occurs in combination with orbital and intracranial involvement. Clinically this entity is of great importance, since it represents a severe disease with possibly disastrous consequences. PATIENTS: Aetiology, diagnosis and therapy of acute pansinusitis and its complications were analysed in 36 patients treated surgically from 1987 to 1996. RESULTS: Eighteen patients were aged between 3 and 21-years-old. Only eight suffered from pure pansinusitis, and three of an isolated purulent orbital infection. Of these 25 patients 20 had (pan-)sinusitis with orbital, three with intracranial, and two with both orbital and intracranial complications. Intracranial involvement included meningitis, empyema and brain abscess. Aetiology was rhinogenic in 26, odontogenic in six patients, and traumatic in two cases. Radiological work-up included conventional radiographs and CT in most cases, MRI was only used with special indications. Microbiological examination detected single or multiple species of micro-organisms with equal frequency. If multiple species were found, infection was mostly aerobic/anaerobic in combination. CONCLUSION: These purulent processes, frequently seen in young patients, require immediate surgical intervention and drainage with elimination of the cause of the disease if possible. Cooperation with other specialities is essential depending on the spread of the disease. In spite of the threatening acute symptoms, severe courses of disease or permanent defects should be avoidable.

[Life threatening and fatal complications of radical neck dissection]. / Lebensbedrohliche und letale Komplikationen der Neck dissection.

BACKGROUND: Between 1990 and 1999, 395 neck dissections were performed in 357 patients: 195 left-sided (105 of these radical) and 200 right-sided (107 of these radical). Life-threatening complications occurred in four cases and two patients died. CASE REPORTS: After left-sided radical neck dissection with chylous fistula, a chylothorax resulted, which could not be controlled in spite of chest tube drainage and thoracotomy so that the 75-year-old female patient died 30 days postoperatively. A 66-year-old man died 35 days after a functional neck dissection of the left side because of extreme chylous flow of up to 7 l/day in spite of parenteral nutrition, local surgical revision, and intrathoracic ligation of the thoracic duct. Undetected cirrhosis of the liver was regarded to be the reason for this extremely increased lymph flow. In a 63-year-old man, a jugular foramen hemorrhage during radical neck dissection could only be managed after 3 h and approximately 6 l of blood loss. In a 66-year-old man, a discrete injury of the pleura led to cardiovascular failure due to a tension pneumothorax with mediastinal shift about 45 min later, which required immediate chest tube placement. DISCUSSION: In none of these unusual cases, which accounted for 1% of all evaluated interventions, had the patients been informed about the observed complication. However, no legal consequences resulted. Nevertheless, dramatic courses of chylous fistulas and rare complications should be considered both forensically when seeking informed consent and clinically.