Kilian Kreutzer

Fluorescence-Guided Bone Resection in Bisphosphonate-Related Osteonecrosis of the Jaws: First Clinical Results of a Prospective Pilot Study

PURPOSE Surgical debridement is the therapy of choice in advanced stages of bisphosphonate-related osteonecrosis of the jaws (BRONJ). However, the therapy is currently only loosely standardized because no suitable imaging modalities exist. This study aims to redress this by exploring the suitability and reproducibility of applying a fluorescence-guided bone resection to patients with BRONJ. PATIENTS AND METHODS This prospective pilot study comprised 15 patients with 20 BRONJ lesions (only stages II and III) with a history of intravenous bisphosphonate treatment for metastatic bone diseases. Before surgical treatment, each patient received a 10-day administration of doxycycline. Fluorescence-guided resection of necrotic bone was performed by means of a certified fluorescence lamp. Success of the procedure was proclaimed if mucosal closure was observed and symptoms were absent 4 weeks postoperatively. RESULTS The 4-week postoperative follow-up identified a mucosal closure in 17 of 20 BRONJ lesions (85%). These patients were free of any symptoms. Failure as defined by mucosal dehiscence and exposed bone was observed in 3 of 20 BRONJ lesions (15%). CONCLUSION The success rate of this surgical regimen of BRONJ was respectable, and thus fluorescence-guided bone resection can be considered an effective treatment for stage II and stage III BRONJ. Furthermore, the reproducibility of the technique offers an opportunity to standardize the surgical therapy. Further studies are called for that compare the fluorescence-guided bone resection with conventional surgical approaches, as well as surgical versus conservative treatment in the early stages (stages 0 and I) of BRONJ.

Fluorescence-Guided Bone Resection in Bisphosphonate-Associated Osteonecrosis of the Jaws

PURPOSE To date, the therapy of bisphosphonate-associated osteonecrosis of the jaws (BONJ) has been hampered by the lack of imaging modalities that enable the extent of necrosis to be visualized. This study aims to demonstrate the feasibility of tetracycline fluorescence guided bone resection in the surgical management of BONJ. PATIENTS AND METHODS Following a 10-day preoperative administration of doxycycline in patients suffering from BONJ, sufficient doxycycline is incorporated into viable bone to be visualized with a certified medical lamp emitting exciting light at 400 to 460 nm. RESULTS Viable and necrotic bone can be discriminated intraoperatively in a routine and reproducible manner by doxycycline bone fluorescence. CONCLUSION In the therapy of BONJ, conservative concepts are to be favored. The fact that necrotic bone can now be selectively resected signifies an improvement of the conservative surgical therapy of BONJ.

Bisphosphonate related osteonecrosis of the jaw: A minipig large animal model☆

Bisphosphonate related osteonecrosis of the jaw (BRONJ) is rare but potentially severe, and the etiopathology and risk factors are poorly defined. To date, it has not been possible to induce BRONJ in a large animal model, a shortfall this study aims to redress. Ten two-year-old adult Göttingen minipigs were split into two groups. Five pigs (group 1) were administered intravenously a weekly dose of a bisphosphonate (zoledonate 0.05mg/kg body weight, approximating the oncologic dose in humans) and five pigs (group 2) served as controls. After 6 weeks, tooth extractions were performed in the upper and lower jaw (both groups) and the bisphosphonate administration continued for a further 10 weeks (group 1 only). Clinical and blood parameters were monitored throughout the entire experiment; thereafter, the jaw-bones were subjected to macroscopic, radiological (CT) and histological investigations. Whilst the extraction sites in the control group healed within two weeks, all animals in the bisphosphonate group exhibited exposed bone and impaired wound healing, indicators that are synonymous of macroscopically advanced osteonecrosis. Radiological and in particular histological investigations confirmed the presence of BRONJ in the animals from group 1. This paper demonstrates that the administration of bisphosphonates, in combination with tooth extractions, induces BRONJ in a minipig model. The ability to study BRONJ in miniature pigs, animals with a bone structure not dissimilar to humans, may improve our knowledgebase regarding the etiopathology, the prophylaxis and potentially uncover new therapies of BRONJ.

Tetracycline Bone Fluorescence: A Valuable Marker for Osteonecrosis Characterization and Therapy

PURPOSE Differential diagnosis of osteoradionecrosis and bisphosphonate-related osteonecrosis of the jaw is primarily based on medical history, rather than pathogenesis or histopathology. This report aims to redress this shortcoming by demonstrating the advantages of tetracycline bone fluorescence as an aid to characterize osteonecrosis entities according to differential histopathologies. Furthermore, this technique facilitates the means to determine extent of necrosis and to optimize surgical therapy. PATIENTS AND METHODS Two patients with extended osteonecrosis of the lower jaw (osteoradionecrosis or bisphosphonate-related osteonecrosis of the jaw) were treated with partial mandibulectomy. After preoperative administration of doxycycline for 10 days, bone fluorescence was monitored intraoperatively to determine the resection boundaries. RESULTS Fluorescence analysis correlated well with the specific histopathologic features of the 2 osteonecrosis entities. Bone fluorescence was predominantly observed in the cortical bone and cancellous bone regions in osteoradionecrosis and bisphosphonate-related osteonecrosis of the jaw, respectively. Margins of the osteonecrosis (and the resection) could be determined under fluorescence guidance; however, bone bleeding did not correlate with bone fluorescence in both osteonecrosis entities. CONCLUSIONS Given that viable but not necrotic bone displays tetracycline fluorescence, a notion that reflects the histopathology, more precise characterization of the 2 osteonecrosis types is enabled. Furthermore, even in extended cases of osteonecrosis requiring partial mandibulectomy, bone fluorescence helps to pinpoint the margins of resection and thus signifies an improvement of surgical therapy of extended osteonecrosis.

Characterization of eight different tetracyclines: advances in fluorescence bone labeling.

Polychrome sequential labeling with fluorochromes is a standard technique for the investigation of bone formation and regeneration processes in vivo. However, for human application, only tetracycline and its derivates are approved as fluorochromes. Therefore, the aim of this study was to determine the fluorescence characteristics of the different tetracycline derivates to assess the feasibility of sequential in vivo bone labeling using distinguishable fluorochromes. Eight different tetracycline derivates were injected subcutaneously into growing rats as a single dose or sequentially in different combinations. After preparation of resin‐embedded undecalcified bone sections, the fluorescence properties of the tetracycline derivates in bone were analyzed using conventional fluorescence microscopy, spectral image analysis and confocal laser scanning microscopy. Each tetracycline derivate exhibited a characteristic fluorescence spectrum, but the differences between them were small. Chlortetracycline could be discriminated reliably from all other derivates and could therefore be combined with any other tetracycline derivate for reliably distinguishable double labeling. Tetracycline itself exhibited the brightest fluorescence of all the investigated derivates. Interestingly, in conventional microscopy the same tetracycline derivative can appear in different colours to the human eye, even if spectral analysis confirmed identical emission peaks. In conclusion, the data suggest that fluorescence double labeling of bone is feasible using appropriate tetracycline derivates in combination with spectral imaging modalities.

Repair of oronasal fistulas with human amniotic membrane in minipigs

We evaluated the use of multilayer human amniotic membrane (HAM) as a grafting material for the repair of mid-palate oronasal fistulas in seven Berlin minipigs. After two weeks, three animals had the fistulas repaired with multilayered HAM grafts, three had them repaired with a collagen-based dermal substitute (INTEGRA((R)), Integra Life Sciences, Plainsboro, NJ, USA), and one fistula was left untreated to serve as a control. Grafts were interposed between the oral and nasal mucosa, traversing the fistulas. After healing for 40 days, the pigs were killed for clinical, histological, and immunohistochemical examination. Two of the three fistulas closed with HAM were successful, the diameter of the third was reduced in size, and there was no change in the diameter of the fistula in the control. This study shows successful closure of oronasal fistulas in minipigs using interposed grafts of cryopreserved HAM, and offers promise as a simple and effective technique for tension-free closure of such fistulas.

Current evidence regarding prophylactic antibiotics in head and neck and maxillofacial surgery.

Antibiotic prophylaxis is commonly used to decrease the rate of infections in head and neck surgery. The aim of this paper is to present the available evidence regarding the application of antibiotic prophylaxis in surgical procedures of the head and neck region in healthy patients. A systemic literature review based on Medline and Embase databases was performed. All reviews and meta-analyses based on RCTs in English from 2000 to 2013 were included. Eight out of 532 studies fulfilled all requirements. Within those, only seven different operative procedures were analyzed. Evidence exists for the beneficial use of prophylactic antibiotics for tympanostomy, orthognathic surgery, and operative tooth extractions. Unfortunately, little high-level evidence exists regarding the use of prophylactic antibiotics in head and neck surgery. In numerous cases, no clear benefit of antibiotic prophylaxis has been shown, particularly considering their potential adverse side effects. Antibiotics are often given unnecessarily and are administered too late and for too long. Furthermore, little research has been performed on the large number of routine cases in the above-mentioned areas of specialization within the last few years, although questions arising with respect to the treatment of high-risk patients or of specific infections are discussed on a broad base.

A novel non-viral gene delivery tool of BMP-2 for the reconstitution of critical-size bone defects in rats.

The osseointegration of bone implants, implant failure, and the bridging of critical-size bone defects are frequent clinical challenges. Deficiencies in endogenous bone healing can be resolved through the local administration of suitable recombinant growth factors (GFs). In preclinical models, gene-therapy-supported bone healing has proven promising for overcoming certain limitations of GFs. We report the dose-dependent bridging of critical-size mandibular bone defects (CSDs) in a rat model using a non-viral BMP-2-encoding copolymer-protected gene vector (pBMP-2) embedded in poly(d, l-lactide) (PDLLA) coatings on titanium discs that were used to cover drill holes in the mandibles of 53 male Sprague Dawley rats. After sacrificing, the mandibles were subjected to micro-computed tomography (µCT), micro-radiography, histology, and fluorescence analyses to evaluate bone regeneration. pBMP-2 in PDLLA-coated titanium implants promoted partial bridging of bone defects within 14 days and complete defect healing within 112 days when the DNA dose per implant did not exceed 2.5 µg. No bridging was observed in untreated control CSDs. Thus, the delivery of plasmid DNA coding for BMP-2 appears to be a potent method for controlled new-bone formation with an inverse dose dependency.

Sandwich flaps as a feasible solution for the management of huge mandibular composite tissue defects

In the current therapy of head and neck defects, surgical reconstruction with the aid of pedicle or free flaps is common practice. Suitable single flaps are available to solve most reconstructive challenges. However, reconstruction can become a problem in extensive mandibular defects, as they are often caused by large primary tumors or osteoradionecrosis. These composite defects often lead to large intraoral or extraoral fistulas due to the involvement of mucosa, skin, mandible and soft tissue. These issues call for a double flap approach in order to achieve adequate reconstruction. Therefore, we developed a surgical sandwich technique as presented in this study. The procedure features the acquisition and use of two vascular flaps which can be freely combined according to their desired features (for example being of high tissue volume or osteomyocutaneous). In our study we included 11 patients (ten male, one female) with a mean age of 57 years. Seven of the patients had defects due to osteoradionecrosis and four due to tumor resection. A sandwich technique was performed in a single operation in eight patients, whereas for three patients several operations were necessary. The flaps used included: fibula free flap (FFF); anterolateral thigh (ALT); radial forearm flap (RFF); deltopectoral flap (DPF) and tensor fascia lata (TFL). The following combinations were used: FFF and ALT (three cases), FFF and RFF (two), FFF and DPF (three), ALT and TFL (two), and two ALT flaps (one). The sandwich technique proved suitable for complex reconstructions and led to desirable esthetic and functional results. The flexibility in combining different free or pedicle flaps made it possible to address various defect situations and consequently offer satisfactory surgical reconstruction for complex cases.

Decreased cognitive functioning in patients with advanced oral squamous cell carcinoma

Cognitive impairment causes a delay in diagnosis and treatment of the various cancer entities, resulting in reduced surgical outcomes and patient survival. However, no investigations have been carried out as to whether an association exists between cognitive functioning and tumour size in patients with oral squamous cell carcinoma (OSCC). In this study, 46 patients with OSCC were evaluated by using a screening test for dementia, consisting of a combination of the mini-mental state examination and the clock test (81% sensitivity and 90% specificity). Test scores were correlated with tumour size according to the TNM staging system, which was categorized as being either limited (T1, T2; n=24) or advanced (T3, T4; n=22). No difference in age (P=0.172), sex (P=0.330), the percentage of drinkers (P=0.090) or the percentage of smokers (P=0.484) was evident between the groups. Patients with advanced tumour size scored significantly lower (median 5.5 of 9 possible points) when compared with those having tumours of a limited size (median 9 of 9 possible points; P=0.005). The median score of patients with T3/T4 tumours suggested the need for comprehensive neuropsychological evaluations for dementia. In conclusion, this study has demonstrated the correlation of reduced cognitive functioning in patients with advanced OSCC. As a consequence, instructions for the identification of early signs and of symptoms of oral cancer are strongly recommended for relatives and nursing staff of patients with cognitive impairment. Such patients might need immediate treatment for oral cancer but might not be able to understand the significance of their symptoms and therefore present late, often too late.