Stephan Rupprecht

Hydroxyapatite cement (BoneSourceTM) for repair of critical sized calvarian defects—an experimental study

AIM In an experimental study the hydroxyapatite cement BoneSource was tested for the ability in relation to the defect size and for its resorption properties. MATERIAL AND METHODS In an animal study, BoneSource was applied to repair bicortical defects of different sizes in frontal bones of six Goettingen minipigs. The area was evaluated radiographically and histologically 12, 18 and 40 weeks postoperatively. RESULTS After 40 weeks approximately 90% of the hydroxyapatite cement had been resorbed and replaced with bone. After 12 weeks, approximately 30% had been degraded, and 40% after 18 weeks. In small bone defects, the mucosa of the frontal sinus lined the bone substitute (BoneSource). In the reconstruction of large areas, a membrane was used to stabilize the material. Despite this membranous support, BoneSource material prolapsed into the frontal sinus. DISCUSSION Hydroxyapatite cement is for the repair of bone defects. It can be moulded to shape the reconstruction. Its use is limited by the defect size and the need for a dry bed. CONCLUSION BoneSource is well suited to repair small defects with proven high biocompatibility. However, in large defects, the material is not sufficiently stable.

Sensor-based laser ablation for tissue specific cutting: an experimental study

The interaction of laser light and tissue causes measurable phenomenons. These phenomenons can be quantified and used to control the laser drilling within a feedback system. Ten halves of dissected minipig jaws were treated with an Er:YAG laser system controlled via a feedback system. Sensor outputs were recorded and analyzed while osteotomy was done. The relative depth of laser ablation was calculated by 3D computed tomography and evaluated histologically. The detected signals caused by the laser–tissue interaction changed their character in a dramatic way after passing the cortical bone layer. The radiological evaluation of 98 laser-ablated holes in the ten halves showed no deeper ablation beyond the cortical layer (mean values: 97.8%). Histologically, no physical damage to the alveolar nerve bundle was proved. The feedback system to control the laser drilling was working exactly for cortical ablation of the bone based on the evaluation of detected and quantified phenomenon related to the laser–tissue interaction.

Preclinical animal model for de novo bone formation in human maxillary sinus

OBJECTIVES Up to now the effect of bone-substitute materials on de novo bone formation has been tested in a variety of preclinical animal models. We hypothesized that there is no significant difference in bone regeneration after application of autogenous bone (AB) and bone substitutes in a porcine calvarial monocortical defect model and in human maxillary sinus. STUDY DESIGN Twenty-four weeks after application of ss-tricalcium phosphate (betaTCP), hydroxyapatite (HA), and AB in each of 3 defects on the sculls of 6 adult pigs (N = 54) and the application in 44 sinus floor elevations (11x betaTCP, 6x HA and 24x AB) in 41 patients, bone regeneration rates where compared microradiographically. Wilcoxon rank-sum test was used for statistical analysis. RESULTS Comparing the human with the animal specimens microradiographically, no significant difference of the mineralization rate could be found. CONCLUSION The chosen porcine model is a valuable method for preclinical testing of bone-substitute materials in maxillofacial surgery.

In Vivo Evaluation of ß-TCP Containing 3D Laser Sintered Poly(ether ether ketone) Composites in Pigs

The aim of this study was to produce an individually shaped medical implant from a 3D database and to evaluate the biological behavior of a laser sintered poly(ether ether ketone) (PEEK) implant with incorporated osteoconductive bone materials in porcine bone defects. Laser sintered PEEK samples containing ß-tricalciumphosphate (ß-TCP) were implanted into critical size defects in the frontal skull of ten pigs. Compression moulded pure PEEK was used as a reference material. The bone-implant interface was histomorphometrically analysed after 6, 12, and 24 weeks. Histomorphometrical evaluations after 24 weeks revealed that the superficially located ß-TCP was in contact with the surrounding bone, whereas the other groups were fibrous encapsulated. Interfacial shear strength was significantly higher for the ß-TCP containing group in comparison to the compression moulded PEEK group (p = 0.004) and the laser sintered PEEK group. The laser sintered PEEK implants seem to be attractive as bone substitutes for reconstructive surgery due to their individually constructed 3D shape and biocompatibility.

Riesenzellgranulom und Osteitis fibrosa cystica bei Hyperparathyreoidismus

Zu ossären Läsionen des Kiefers mit ähnlichem histologischen Bild gehören das zentrale Riesenzellgranulom und braune Tumoren bei Hyperparathyreoidismus. Da auch der radiologische Befund dieser Erkrankungen nahezu identische Merkmale aufweist, ist die differenzialdiagnostische Abgrenzung schwierig. Liegen zusätzlich maligne Grunderkrankungen vor, ist die Abgrenzung von ossären Metastasen ein zusätzliches Problem. Es wird über zwei Patienten mit osteolytischen Läsionen der Maxilla berichtet. In beiden Fällen lag eine maligne Grunderkrankung (Prostatakarzinom, Mammakarzinom) vor, die Zuweisung erfolgte jeweils wegen des Verdachts auf ossäre Metastasierung. Klinisch fanden sich identische Befunde. Die Biopsie zeigte riesenzellhaltige Läsionen des Knochens, wodurch die zunächst vermutete Metastasierung ausgeschlossen werden konnte. Bei einem der Patienten war im Labor der massiv erhöhte Parathormonspiegel auffällig. Aufgrund der raschen Größenprogression wurde initial eine chirurgische Therapie durchgeführt. Im Rahmen der weitergehenden Diagnostik konnte bei diesem Patienten ein Adenom der Nebenschilddrüsen festgestellt werden. Eine kausale Therapie wurde eingeleitet. Die beiden geschilderte Fälle demonstrieren die Schwierigkeiten bei der Differenzialdiagnostik der Riesenzellläsionen des Kiefers. Eine exakte Diagnostik ist für die Einleitung einer adäquaten Therapie jedoch unumgänglich. Die einzelnen Krankheitsbilder werden hier im Zusammenhang mit den notwendigen diagnostischen und therapeutischen Maßnahmen gegenübergestellt. Giant cell lesions of the bone present similar histological features. The differential diagnosis comprises central giant cell granuloma, giant cell tumor of bone, and osteitis fibrosa cystica (brown tumor) in combination with hyperparathyroidism. Since these lesions may mimic metastatic bone disease in patients with a history of cancer, a malignant process has to be considered. Since the treatment and prognosis of these entities—benign versus malignant osteolytic bone processes—differ greatly, definitive differential diagnosis is of utmost importance. Two patients presenting with osteolytic lesions of the maxilla are reported here. In both cases a history of cancer (breast and prostate) suggested bone spreading of these malignant tumors. The clinical and histological findings were similar in both patients. One lesion was diagnosed as central giant cell granuloma, the other was found to be brown tumour in osteitis fibrosa cystica as an initial manifestation of hyperparathyroidism. The presented cases demonstrate the difficulties in establishing the correct diagnosis of patients found to have osteolytic lesions of the jawbones which is critical for the appropriate management of these patients. The article discusses the different entities of osteolytic lesions of the jawbones and the necessary diagnostic and therapeutic approach.

Experimentelle Untersuchung zur Oberflächenaktivierung von Implantaten durch liposomale Vektoren—eine Pilotstudie

BACKGROUND Surface coating with mitogenic or morphogenic proteins can improve the healing of bone adjacent to implants and increase the bone-implant interface. Clinical surveys have shown liposome-mediated gene transfer to be a promising and safe new therapeutic method. The aim of our study was to evaluate an experimental model of new approaches for topical treatment of the implant surface and of periimplant defects by using DNA liposomes encoding for BMP-2 (bone morphogenetic protein). MATERIAL AND METHODS A total of 27 implants (3.5 x 14 mm) were placed in critically sized defects of the frontal skull bone of adult pigs (n=3). The bottom of the implant was placed in the base of the defect which guaranteed primary stability, whereas the superior part of the implant (10 mm) represented an implant in a defect area. Liposomes containing DNA encoding for BMP-2 and GFP (green fluorescence protein) were used. In a first trial GFP-DNA liposomes on a collagen matrix were directly applied to the periimplant defect. In a second stage, the surface of the implants was encoded with BMP-2 DNA liposomes. Subsequently, these implants were inserted in the manner described. The resulting bone samples were prepared for immunohistochemical staining. Staining for GFP was performed in the area of the defect and for BMP-2 on the bone-implant interface. RESULTS Immunohistochemical staining on day 3 postoperatively revealed an increased GFP expression in the periimplant defect. Therefore, the effectiveness of the liposomal vector was verified for the chosen animal model. On the surface of the implants encoded with BMP-2 DNA liposomes an increased BMP-2 expression was found. Thus, the liposomal vector system was validated also for BMP-2 DNA transfer in the chosen animal model. Further, the established system allows a sustainable and delayed release of BMP-2 in the area of the bone-implant interface. CONCLUSIONS As a result of the study we were able to collect data concerning the influence of implant surface conditioning on the bone-implant interface and on therapeutically relevant options for the treatment of periimplant defects. These approaches are currently being evaluated in a long-term study.

W.L. Mang (ed.) Manual of Aesthetic Surgery 2

Springer, Berlin Heidelberg New York, 2005 (ISBN 3-540-66553-6), EUR 219,– Das Manual of Aesthetic Surgery ist als zweibändiges Werk angelegt, das plastisch-chirurgische Eingriffe im Sinne einer „Gebrauchsanweisung“ strukturiert beschreibt. Der erste Band beschäftigt sich vorwiegend mit der plastischen Gesichtschirurgie, wohingegen sich der zweite Band der Technik der Brustaugmentation, des Liftings der Oberarm-, Oberschenkel-, Bauchund Gesäßhaut, der Liposuktion und Haartransplantation sowie der adjuvanten Therapiemöglichkeiten, wie z. B. des nach dem Autor benannten „space lift“, widmet. Die insgesamt sechs Autoren der Bodenseeklinik Lindau beschreiben sehr anschaulich auf insgesamt 272 Seiten nach sehr ausführlichen 43 Seiten verschiedenster Vorworte die aufgezählten Techniken. Die sieben Kapitel enthalten 120 medizinische Zeichnungen, 20 Abbildungen der Instrumentarien und 66 Fotografien. Die einzelnen Kapitel sind nach einer kurzen Einführung konstant gegliedert. Einer anatomischen Übersicht folgt die Beschreibung des chirurgischen Instrumentariums, das der Übersichtlichkeit halber jeweils auf einer Doppelseite fotografisch dargestellt ist, nebst erforderlicher präoperativer Patienteninformation und -aufklärung. Die anschließende Ausführung der Operationstechnik ist sehr anschaulich bebildert und zusätzlich durch die beiliegende DVD mit nach operativen Schritten geordneten Videoclips illustriert. Die entsprechenden „Kurzfilme“ sind gemäß der im Buch vorgegebenen Reihenfolge gegliedert. In der Zusammenschau der Informationen wird dem in der entsprechenden Technik operativen Neuling eine nahtlose Übertragung auf den operativen Situs sehr erleichtert, da das Buch entsprechend der im Titel genannten Intention immer eine strukturierte „Gebrauchsanleitung“ bietet. Am Ende eines jeden Kapitels wird eine knappe Literaturübersicht gewährt. Im letzten Abschnitt „adjuvant therapies“ werden Techniken der Lokalanästhesie (insbesondere Leitungsanästhesie im Gesichtsbereich), biologische Implantate wie Kollagen und Hyaluronsäure, die Anwendung von Botulinumtoxin,„Mang’s space lift“,Dermabrasion, chemischem Peeling und letztendlich auch des Er:YAG-Lasers für die ästhetische Chirurgie abgehandelt. Herauszuheben ist auch hier die gute Bebilderung anhand ausgewählter Patientenfälle im präund postoperativen Vergleich. Das Manual 2 ist die Fortsetzung des 1. Bandes (Rhinoplastik, „face lift“, Augenlidchirurgie,Otoplastik,„adjuvant therapies“, Laserchirurgie) in englischer Sprache und wird vom Springer-Verlag herausgegeben. Der Preis in Höhe von 219 EUR ist durchaus angemessen. Insgesamt ist das Buch empfehlenswert; für die mund-kiefer-gesichts-chirurgische Leserschaft mag der erste Band aufgrund der rein auf die Gesicht-KopfRegion fokussierten Eingriffe von höherem Interesse sein.

Experimentelle Untersuchung zur Oberflchenaktivierung von Implantaten durch liposomale Vektoren?eine Pilotstudie@@@Experimental pilot study on surface activation of implants with liposomal vectors

BACKGROUND Surface coating with mitogenic or morphogenic proteins can improve the healing of bone adjacent to implants and increase the bone-implant interface. Clinical surveys have shown liposome-mediated gene transfer to be a promising and safe new therapeutic method. The aim of our study was to evaluate an experimental model of new approaches for topical treatment of the implant surface and of periimplant defects by using DNA liposomes encoding for BMP-2 (bone morphogenetic protein). MATERIAL AND METHODS A total of 27 implants (3.5 x 14 mm) were placed in critically sized defects of the frontal skull bone of adult pigs (n=3). The bottom of the implant was placed in the base of the defect which guaranteed primary stability, whereas the superior part of the implant (10 mm) represented an implant in a defect area. Liposomes containing DNA encoding for BMP-2 and GFP (green fluorescence protein) were used. In a first trial GFP-DNA liposomes on a collagen matrix were directly applied to the periimplant defect. In a second stage, the surface of the implants was encoded with BMP-2 DNA liposomes. Subsequently, these implants were inserted in the manner described. The resulting bone samples were prepared for immunohistochemical staining. Staining for GFP was performed in the area of the defect and for BMP-2 on the bone-implant interface. RESULTS Immunohistochemical staining on day 3 postoperatively revealed an increased GFP expression in the periimplant defect. Therefore, the effectiveness of the liposomal vector was verified for the chosen animal model. On the surface of the implants encoded with BMP-2 DNA liposomes an increased BMP-2 expression was found. Thus, the liposomal vector system was validated also for BMP-2 DNA transfer in the chosen animal model. Further, the established system allows a sustainable and delayed release of BMP-2 in the area of the bone-implant interface. CONCLUSIONS As a result of the study we were able to collect data concerning the influence of implant surface conditioning on the bone-implant interface and on therapeutically relevant options for the treatment of periimplant defects. These approaches are currently being evaluated in a long-term study.