Kai-Hendrik Bormann

Prefabrication of vascularized bioartificial bone grafts in vivo for segmental mandibular reconstruction: experimental pilot study in sheep and first clinical application

The key elements for bioartificial bone formation in 3D matrices are large numbers of osteogenic cells and supplies of oxygen and nutrition. Vascularization becomes more important with the increasing size and complexity of seeded scaffolds required for clinical application in reconstructive craniomaxillofacial surgery. Prefabrication of vascularized bioartificial bone grafts in vivo might be an alternative to in vitro tissue engineering techniques. Two cylindrical beta-TCP-scaffolds (25 mm long) were intraoperatively filled with autogenous bone marrow from the iliac crest for cell loading and implanted into the latissimus dorsi muscle in 12 sheep. To determine the effect of axial perfusion, one scaffold in each sheep was surgically supplied with a central vascular bundle. Sheep were killed 3 months after surgery. Histomorphometric analysis showed autogenous bone marrow from the iliac crest was an effective source of osteogenic cells and growth factors, inducing considerable ectopic bone growth in all implanted scaffolds. Bone growth, ceramic resorption and angiogenesis increased significantly with axial perfusion. The results encourage the application of prefabricated bioartificial bone for segmental mandibular reconstruction in man. In clinical practice, vascularized bioartificial bone grafts could change the principles of bone transplantation with minimal donor site morbidity and no shape or volume limitations.

Inferior Alveolar Nerve Transposition—An In Vitro Comparison Between Piezosurgery and Conventional Bur Use

An in vitro comparison between a new ultrasound-based piezoelectric device and a conventional bur was performed for lateralization or transposition of the inferior alveolar nerve to evaluate the effects on soft and hard tissue. Transposition of the inferior alveolar nerve was performed in the cadaver mandibles of 10 sheep: the left nerve was uncovered with a saline-cooled diamond-coated spherical bur (2000 rpm), and the right nerve was uncovered with the piezoelectric device mounted with a spherical diamond tip. The surface, the zone of bone defect, and the nerve were examined by light microscopy and laser microscopy. Bone treated with the rotary bur showed significantly smoother surfaces and shallower defect zones (50 microm) in comparison with the piezoelectric device (150 microm). Lesions of the epineurium and an increased amount of bone particles were found in the lesions prepared with the piezoelectric device. In vitro preparation with the piezoelectric device was more invasive to the bone than was a conventional diamond bur. Touching the inferior alveolar nerve resulted in roughening of the epineurium without affecting deeper structures. The degree of injury was lower than when using the conventional rotary bur.

Five-year retrospective study of mandibular fractures in Freiburg, Germany: incidence, etiology, treatment, and complications

PURPOSE To evaluate current trends in maxillofacial trauma, a retrospective review of mandibular fractures at a German university hospital was carried out. PATIENTS AND METHODS In this retrospective study, records of 444 patients with mandibular fractures between 2000 and 2005 at the Department of Oral and Maxillofacial Surgery, University Hospital of Freiburg, Germany, were reviewed. A total of 444 patients presented with 696 mandibular fractures. RESULTS Three hundred twenty-nine (74%) of the fractures occurred in male and 115 (26%) in female patients (2.9:1). One hundred forty-two fractures (32%) resulted from road traffic accidents, 126 from fights (28%), and 116 from falls (26%). Forty-four fractures were caused by sport accidents (10%) and 16 by pathologic fractures (4%). The mandibular condyle area was the most common fracture site, with 291 fractures (42%), followed by 144 fractures of the symphyseal and parasymphyseal area (21%) and 141 angle fractures (20%). Combined fractures were found in nearly half of the cases. Five hundred seventy-nine (83%) of patients with mandibular fractures were treated by surgical intervention, 117 (17%) of patients conservatively. Regarding the surgical treatment, 561 (65%) miniplates, 247 (29%) locking plates, and 51 (6%) lag screws were used. Complications, such as postoperative infections, abscesses, and osteomyelitis appeared in 66 (9%) cases. CONCLUSION We concluded that osteosynthesis of mandibular fractures by miniplates and locking plates are both reliable.

Computer-assisted therapy in orbital and mid-facial reconstructions.

Management of orbital and mid‐facial fractures requires a thorough ophthalmic evaluation and precise imaging. A principle goal of therapy is to anatomically reduce fracture segments and to restore a normal orbital volume as soon as possible. Diagnostic advances such as new surgical and imaging techniques have dramatically improved both the functional and aesthetic outcome of reconstructions.

Computer-assisted navigation in craniomaxillofacial tumors.

Surgical procedures in the head and neck region require a detailed knowledge of this regions complex anatomy. Anatomic changes due to tumor growth present special challenges for the surgeon. In addition to the clinical examination, which is still of fundamental importance, imaging procedures such as computer-aided surgical navigation technology are currently being used in the preoperative, intraoperative, and postoperative assessments of anatomic changes. For purposes of analysis, we have analyzed the application of navigation technology into 2 categories: 1) minimally invasive procedure and biopsy; and 2) resection of extensive tumors and reconstruction after tumor surgery. Navigation can make tumor surgery more reliable by specifying correct safety margins, protecting vital structures, and facilitating the reconstruction process.

Consequences of seeded cell type on vascularization of tissue engineering constructs in vivo

Implantation of tissue engineering constructs is a promising technique to reconstruct injured tissue. However, after implantation the nutrition of the constructs is predominantly restricted to vascularization. Since cells possess distinct angiogenic potency, we herein assessed whether scaffold vitalization with different cell types improves scaffold vascularization. 32 male balb/c mice received a dorsal skinfold chamber. Angiogenesis, microhemodynamics, leukocyte-endothelial cell interaction and microvascular permeability induced in the host tissue after implantation of either collagen coated poly (L-lactide-co-glycolide) (PLGA) scaffolds (group 4), additionally seeded with osteoblast-like cells (OLCs, group 1), bone marrow mesenchymal stem cells (bmMSCs, group 2) or a combination of OLCs and bmMSCs (group 3) were analyzed repetitively over 14 days using intravital fluorescence microscopy. Apart from a weak inflammatory response in all groups, vascularization was found distinctly accelerated in vitalized scaffolds, indicated by a significantly increased microvascular density (day 6, group 1: 202+/-15 cm/cm(2), group 2: 202+/-12 cm/cm(2), group 3: 194+/-8 cm/cm(2)), when compared with controls (group 4: 72+/-5 cm/cm(2)). This acceleration was independent from the seeded cell type. Immunohistochemistry revealed in vivo VEGF expression in close vicinity to the seeded OLCs and bmMSCs. Therefore, the observed lack of cell type confined differences in the vascularization process suggests that the accelerated vascularization of vitalized scaffolds is VEGF-related rather than dependent on the potential of bmMSCs to differentiate into specific vascular cells.

Bone repair by cell-seeded 3D-bioplotted composite scaffolds made of collagen treated tricalciumphosphate or tricalciumphosphate-chitosan-collagen hydrogel or PLGA in ovine critical-sized calvarial defects

The aim of this study was to investigate the osteogenic effect of three different cell-seeded 3D-bioplotted scaffolds in a ovine calvarial critical-size defect model. The choice of scaffold-materials was based on their applicability for 3D-bioplotting and respective possibility to produce tailor-made scaffolds for the use in cranio-facial surgery for the replacement of complex shaped boneparts. Scaffold raw-materials are known to be osteoinductive when being cell-seeded [poly(L-lactide-co-glycolide) (PLGA)] or having components with osteoinductive properties as tricalciumphosphate (TCP) or collagen (Col) or chitosan. The scaffold-materials PLGA, TCP/Col, and HYDR (TCP/Col/chitosan) were cell-seeded with osteoblast-like cells whether gained from bone (OLB) or from periost (OLP). In a prospective and randomized design nine sheep underwent osteotomy to create four critical-sized calvarial defects. Three animals each were assigned to the HYDR-, the TCP/Col-, or the PLGA-group. In each animal, one defect was treated with a cell-free, an OLB- or OLP-seeded group-specific scaffold, respectively. The fourth defect remained untreated as control (UD). Fourteen weeks later, animals were euthanized for histo-morphometrical analysis of the defect healing. OLB- and OLP-seeded HYDR and OLB-seeded TCP/Col scaffolds significantly increased the amount of newly formed bone (NFB) at the defect bottom and OLP-seeded HYDR also within the scaffold area, whereas PLGA-scaffolds showed lower rates. The relative density of NFB was markedly higher in the HYDR/OLB group compared to the corresponding PLGA group. TCP/Col had good stiffness to prepare complex structures by bioplotting but HYDR and PLGA were very soft. HYDR showed appropriate biodegradation, TCP/Col and PLGA seemed to be nearly undegraded after 14 weeks. 3D-bioplotted, cell-seeded HYDR and TCP/Col scaffolds increased the amount of NFB within ovine critical-size calvarial defects, but stiffness, respectively, biodegradation of materials is not appropriate for the application in cranio-facial surgery and have to be improved further by modifications of the manufacturing process or their material composition.

Cone beam CT imaging of airgun injuries to the craniomaxillofacial region

In airgun injuries, the removal of the projectile is often recommended. The material properties of airgun projectiles make it difficult to determine their precise anatomical location using conventional radiological techniques. Conventional X-rays give only a two-dimensional representation of projectiles and do not allow a foreign object to be located precisely. Multi-slice computed tomography (CT) has become a standard tool in diagnosis. Metal objects can cause artefacts in CT scans and make it difficult to identify adjacent anatomical structures. By contrast, cone-beam CT (CBCT) provides three-dimensional images largely free from metal artefacts. The authors present three cases of airgun injuries and discuss the diagnostic and treatment approaches used. CBCT has proved to be a useful diagnostic tool in planning the treatment of craniofacial airgun injuries. It is superior to CT in detecting hard-tissue structural damage in the immediate vicinity of high-density metal projectiles.

Speech and Swallowing Impairment After Treatment for Oral and Oropharyngeal Cancer

OBJECTIVES To assess the prevalence of speech and swallowing impairment after radical surgery for oral and oropharyngeal cancer from the patients viewpoint and to examine the association of these functional alterations with selected clinical characteristics regarding patients, tumors, and oncologic treatment. DESIGN Cross-sectional, multicenter study using a self-administered questionnaire. SETTING Forty-three hospitals in Germany, Switzerland, and Austria. PATIENTS A total of 3894 questionnaires about rehabilitation problems after treatment for oral and oropharyngeal squamous cell carcinoma were sent to patients. Of these, 1652 were filled out and returned, and 1334 (80.8%) met the inclusion criteria. MAIN OUTCOME MEASURES Morbidity associated with treatment of oral and oropharyngeal cancer. RESULTS Speech problems were reported by 851 patients (63.8%), and swallowing problems were reported by 1006 patients (75.4%). The variables that presented a significant association with speech and swallowing impairment were sex, tumor location, pTNM stages, stage of tumor, treatment modality, and reconstruction type. CONCLUSIONS This survey, based on patient perception, suggests that those who undergo radiotherapy associated with the surgical removal of a tumor, have late-stage tumors (III-IV), or have tumors located in the floor of the mouth should be informed of the greater risk of persistent severe speech and swallowing problems.

Effects of VEGF loading on scaffold-confined vascularization

Adequate vascularization of tissue-engineered constructs remains a major challenge in bone grafting. In view of this, we loaded ß-tricalcium-phosphate (ß-TCP) and porous poly(L-lactide-co-glycolide) (PLGA) scaffolds via collagen coating with vascular endothelial growth factor (VEGF) and studied whether the VEGF loading improves scaffold angiogenesis and vascularization. Dorsal skinfold chambers were implanted into 48 balb/c mice, which were assigned to 6 groups (n = 8 each). Uncoated (controls), collagen-coated, and additionally VEGF-loaded PLGA and ß-TCP scaffolds were inserted into the chambers. Angiogenesis, neovascularization, and leukocyte-endothelial cell interaction were analyzed repeatedly during a 14-day observation period using intravital fluorescence microscopy. Furthermore, VEGF release from PLGA und ß-TCP scaffolds was studied by ELISA. Micromorphology was studied from histological specimens. Unloaded ß-TCP scaffolds showed an accelerated and increased angiogenic response when compared with unloaded PLGA scaffolds. In vitro, PLGA released significantly higher amounts of VEGF compared with ß-TCP at the first two days resulting in a rapid drop of the released amount at the following days up to day 7 where the VEGF release was negligible. Nonetheless, in vivo VEGF loading increased neovascularization, especially in ß-TCP scaffolds. This increased vascularization was associated with a temporary leukocytic response with pronounced leukocyte-endothelial cell interaction at days 3 and 6. Histology revealed adequate host tissue response and engraftment of both ß-TCP and PLGA scaffolds. Our study demonstrates that ß-TCP scaffolds offer more suitable conditions for vascularization than PLGA scaffolds, in particular if they are loaded with VEGF.