Rudolf Seemann

Risk factors for postoperative bleeding after thyroid surgery

Postoperative bleeding after thyroid surgery is a feared and life‐threatening complication. The aim of the study was to identify risk factors for postoperative bleeding, with special emphasis on the impact of the individual surgeon and the time to diagnosis of the complication.

TREATMENT RESULTS OF BISPHOSPHONATE-RELATED OSTEONECROSIS OF THE JAWS

Osteonecrosis of the jaws occurs after the administration of bisphosphonates. An unequivocal treatment strategy is yet to be devised. We assess the treatment of patients with bisphosphonate‐related osteonecrosis of the jaws (BRONJ).

Stability of miniature electromagnetic tracking systems

This study aims at a comparative evaluation of two recently introduced electromagnetic tracking systems under reproducible simulated operating-room (OR) conditions: the recently launched Medtronic StealthStation, Treon-EM and the NDI Aurora. We investigate if and to what extent these systems provide improved performance and stability in the presence of surgical instruments as possible sources of distortions compared with earlier reports on electromagnetic tracking technology. To investigate possible distortions under pseudo-realistic OR conditions, a large Langenbeck hook, a dental drill with its handle and an ultrasonic (US) scanhead are fixed on a special measurement rack at variable distances from the navigation sensor. The position measurements made by the Treon-EM were least affected by the presence of the instruments. The lengths of the mean deviation vectors were 0.21 mm for the Langenbeck hook, 0.23 mm for the drill with handle and 0.56 mm for the US scanhead. The Aurora was influenced by the three sources of distortion to a higher degree. A mean deviation vector of 1.44 mm length was observed in the vicinity of the Langenbeck hook, 0.53 mm length with the drill and 2.37 mm due to the US scanhead. The maximum of the root mean squared error (RMSE) for all coordinates in the presence of the Langenbeck hook was 0.3 mm for the Treon and 2.1 mm for the Aurora; the drill caused a maximum RMSE of 0.2 mm with the Treon and 1.2 mm with the Aurora. In the presence of the US scanhead, the maximum RMSE was 1.4 mm for the Treon and 5.1 mm for the Aurora. The new generation of electromagnetic tracking systems has significantly improved compared to common systems that were available in the middle of the 1990s and has reached a high level of technical development. We conclude that, in general, both systems are suitable for routine clinical application.

Wobbled splatting—a fast perspective volume rendering method for simulation of x-ray images from CT

3D/2D registration, the automatic assignment of a global rigid-body transformation matching the coordinate systems of patient and preoperative volume scan using projection images, is an important topic in image-guided therapy and radiation oncology. A crucial part of most 3D/2D registration algorithms is the fast computation of digitally rendered radiographs (DRRs) to be compared iteratively to radiographs or portal images. Since registration is an iterative process, fast generation of DRRs-which are perspective summed voxel renderings-is desired. In this note, we present a simple and rapid method for generation of DRRs based on splat rendering. As opposed to conventional splatting, antialiasing of the resulting images is not achieved by means of computing a discrete point spread function (a so-called footprint), but by stochastic distortion of either the voxel positions in the volume scan or by the simulation of a focal spot of the x-ray tube with non-zero diameter. Our method generates slightly blurred DRRs suitable for registration purposes at framerates of approximately 10 Hz when rendering volume images with a size of 30 MB.

Evaluation of immunohistochemical expression of p53, p21, p27, cyclin D1, and Ki67 in oral and oropharyngeal squamous cell carcinoma

BACKGROUND The purpose of this study was to evaluate whether the immunohistochemical expression of p53, p21, p27, cyclin D1, and Ki67 can predict therapy response and survival in patients with oral and oropharyngeal squamous cell carcinoma treated with preoperative chemoradiation. METHODS Biomarker expression was evaluated by immunohistochemistry in formalin-fixed, paraffin-embedded pretreatment biopsies of 111 homogenously treated patients. We assessed the association between clinicopathological variables including response to neoadjuvant chemoradiotherapy as well as the survival of the patients and the expression of the biomarkers as both dichotomized (positive vs. negative) and continuous variables. RESULTS Biomarker overexpression on the basis of pre-selected cutoff points was seen in 66 of 111 (59%) cases for p53, in 77 (69%) for p21, in 48 (43%) for p27, in 81 (73%) for cyclin D1, and in 54 (49%) cases for Ki67, respectively. None of the examined biomarkers was able to predict response to neoadjuvant chemoradiotherapy or was associated with survival outcome. Post-treatment pathologic TNM stage (P < 0.001), pathologic response (P < 0.001), and perineural invasion (P < 0.001) were the only factors having a significant effect on recurrence-free survival. Post-treatment pathologic N stage (P = 0.005), post-treatment pathologic TNM stage (P < 0.001), pathologic response (P < 0.001), and perineural invasion (P = 0.001) had a significant impact on overall survival. CONCLUSIONS Our results suggest that the biomarkers p53, p21, p27, cyclin D1, and Ki67 have no impact on treatment response and survival in patients with oral and oropharyngeal cancer treated with preoperative chemoradiation.

Antibiotic susceptibility and resistance of the odontogenic microbiological spectrum and its clinical impact on severe deep space head and neck infections

OBJECTIVE The purpose of this retrospective study was to identify the major pathogens responsible for deep space head and neck infections and their current resistance to routinely used antibiotics in a university hospital setting. STUDY DESIGN A total of 206 patients suffering from odontogenic deep space infections were treated at our department by means of surgical intervention and intravenous administration of antibiotics. RESULTS The predominant bacteria were viridans group streptococci (VGS), staphylococci, Prevotella, Peptostreptococcus, and Bacteroides. In the aerobic spectrum, resistance against clindamycin was found in 18%, against macrolides in 14%, and against penicillin G in 7%. The anaerobes were resistant to clindamycin in 11%, to metronidazole in 6%, and to penicillin G in 8%. CONCLUSION The high resistance rate for clindamycin and macrolides was especially striking and may necessitate an adaptation of our antibiotic regime in the future.

Factors influencing surgical treatment of bisphosphonate‐related osteonecrosis of the jaws

Bisphosphonates are known to be associated with osteonecrosis of the jaw. We assess factors underlying the success of surgical treatment in patients with bisphosphonate‐related osteonecrosis of the jaw (BRONJ).

Complication rates in the operative treatment of mandibular angle fractures: a 10-year retrospective.

PURPOSE Large-scale studies assessing complication rates and correlation of complications are still missing considering different fracture locations in the mandible. In the present retrospective study, complication rates of mandibular angle fractures treated by open reduction were assessed. MATERIALS AND METHODS Three hundred twenty-two patients (259 men, 63 women) with 335 surgically treated mandibular angle fractures were included in this study. RESULTS Fractures were caused by fights (46.6%), falls (19.2%), traffic accidents (14.6%), sports (11.9%), wisdom tooth removal (7.3%), and 0.9% other causes. Successful treatment occurred in 93.69% of fractures with 1 open reduction and in 6.31% with 2 open reductions. Of surgically treated patients, 71.47% (238) were completely free of complications. A detailed complication correlation matrix is given in the text. Ninety-five fractures treated with 1 miniplate, 170 with 2 miniplates, and 70 with other osteosynthesis concepts were compared regarding osteosynthesis failure and pseudarthrosis. CONCLUSION Similar osteosynthesis failure rates were shown for 1 miniplate and 2 miniplates.

Complications after free flap surgery: do we need a standardized classification of surgical complications?

Our main objective was to apply a standard classification to surgical complications after free flap surgery for reconstructions of the head and neck. We used the modified Clavien-Dindo classification in a cohort of 79 patients who were having reconstructions with jejunal free flaps simultaneously with resections of oral and oropharyngeal cancer. The most common minor complication was the need for a blood transfusion, and the most common major complication of a respiratory nature. The medical complications, and those at the recipient site and the donor site were 53/79 (67%), 44/79 (56%), and 9/79 (11%), respectively. The Clavien-Dindo classification is suitable and can easily be used to evaluate postoperative complications after free tissue transfer.

Application of platelet-rich plasma for enhanced bone regeneration in grafted sinus.

PURPOSE The present study was conducted to evaluate the effect of platelet-rich plasma (PRP) on new bone formation and remodeling after grafting of the maxillary sinus with an algae-derived hydroxyapatite AlgOss/C Graft/Algipore. MATERIALS AND METHODS Fourteen consecutive patients with severely atrophic maxillae underwent uni- or bilateral grafting of the maxillary sinus with a mixture of collected bone, algae-derived hydroxyapatite AlgOss/C Graft/Algipore (ratio 1:10), and a combined addition of PRP and thrombin (Tissucol Kit; Baxter, Vienna, Austria) to allow for fast clotting. After an average healing period of 7.1 months bone samples were retrieved. Patients from a former consecutive series treated without PRP served as control group. Statistical analysis was done by Welch 2-sample t test and mixed linear model testing. RESULTS In the coronal specimen portions, mean values for newly formed bone area, biomaterial area and marrow space of 32.2% ± 10.4%, 20.1% ± 13.0%, and 47.7% ± 8.5% were found with PRP, respectively. In the control group the corresponding values were 27.6% ± 13.4%, 20.3% ± 12.9%, and 52.1% ± 9.3%. In the apical specimen portions in the PRP group, the newly formed bone area, biomaterial area, and marrow space was 25.7% ± 15.0%, 23.4% ± 14.9%, and 50.9% ± 12.5%, respectively. The corresponding values in the control group were 17.0% ± 8.6%, 34.5% ± 11.2%, and 48.5% ± 8.5%. CONCLUSIONS Statistical evaluation of the samples proved significantly better overall resorption of algae-derived hydroxyapatite AlgOss/C Graft/Algipore and increased new bone formation when PRP was used, especially in the apical region.