Vergleich der präoperativen Planung mit dem postoperativen Ergebnis bei computergestützt geplanten posttraumatischen Rekonstruktionen des Mittelgesichts

Das Ziel der Arbeit ist die postoperative Implantat- und Knochensegmentposition mit der präoperativ geplanten virtuellen Position bei sekundären Rekonstruktionen des Mittelgesichtsskeletts und primären Rekonstruktionen der Orbitawände ohne Verwendung von Navigationssystemen zu vergleichen. Die erste Studie wertet die Implementierung der VSP zur sekundären Korrektur von posttraumatischen Deformitäten im Bereich des lateralen und zentralen Mittelgesichts (des Jochbeines, Jochbogens und Oberkiefers) aus. Die zweite Studie untersucht die Implementierung der VSP zur primären Rekonstruktion der inferioren und medialen Orbitawände. Die Patientenkohorte in der ersten Studie besteht aus Patienten, die von 2013 bis 2019 in der Klinik für Mund-, Kiefer- und Gesichtschirurgie der LMU München wegen zuvor nicht adäquat versorgter Frakturen im zentralen und lateralen Mittelgesichtsbereich operativ behandelt wurden. Patienten mit isolierten Orbitawand- oder Le Fort I-Frakturen wurden von der Studie ausgeschlossen. In der zweiten Studie wurden Patienten retrospektiv eingeschlossen, die von 2015 bis 2019 in der Klinik für Mund-, Kiefer- und Gesichtschirurgie der LMU München aufgrund von isolierten Orbitawandfrakturen operiert wurden. 8 Patienten wurden in die erste Studie und 27 Patienten in die zweite Studie aufgenommen. Die mediane Abweichung zwischen geplanter und definitiver Position für die PSI und die Knochensegmente wurde erstens zwischen den gesamten Modelloberflächen mittels einem geeigneten Algorithmus der Software 3-Matic und zweitens an anatomisch korrespondierenden Referenzpunkten ausgemessen, analysiert und ausgewertet. In der ersten Studie betrugen die medianen Abstände zwischen der virtuell geplanten und der postoperativen Position der PSI 2,01 mm (n = 18) gegenüber einem medianen Abstand bezüglich der Knochensegmente von 3,05 mm (n = 12). Bei Patienten, bei denen PSI verwendet wurden, war die mediane Verschiebung der Knochensegmente geringer als in der Gruppe mit vorgebogenen Platten. Darüber hinaus konnte der Jochbeinbereich mit geringerer Abweichung als der Oberkieferbereich positioniert werden. Ferner zeigte sich die Zahnbogenregion im Vergleich zur kranialen Oberkieferregion eine höhere Positionierungsgenauigkeit. In der zweiten Studie zeigten die Medianwerte für die Referenzpunktabmessungen eine größere Abweichung bei den Implantaten zur Versorgung der medialen Orbitawand, nämlich 0,79 mm. Der Wert für die Gruppe der Orbitabodenimplantate lag bei 0,45 mm. Es konnte keine Korrelation zwischen der postoperativen Diplopie und der Passgenauigkeit der Implantatposition nachgewiesen werden. Die vorliegende Arbeit zeigt erstens die Machbarkeit der Übertragung der VSP durch CAD/CAM Werkzeuge für die sekundäre Rekonstruktion komplexer posttraumatischer Restdeformitäten im Mittelgesicht, jedoch mit relativ erhöhter Ungenauigkeit, und zweitens die Möglichkeit einer genauen Umsetzung der Planungsposition bei der Rekonstruktion der inferioren und/oder medialen Orbitawand. Die in der ersten Studie beobachteten höheren Abweichungen lassen sich durch Unterschiede in der Bewertungsmethode sowie durch die Komplexität der Deformitäten, Osteotomien und chirurgischen Verfahren erklären, so dass der Einsatz von Navigationssystemen die Genauigkeit der Repositionierung weiter verbessern könnte

Miniplatten aus Titan zur Fixation von Gelenkfortsatzfrakturen des Unterkiefers: Evaluation des biomechanischen Verhaltens mittels der Finite-Elemente-Analyse

The current publications aimed first to determine which plating technique provides the most rigid fixation and the best biomechanical behavior and second, to examine how the positioning of the lambda plate affects the rigidity of fixation. To assess the rigidity of the osteosynthesis, the displacements of the condylar fragments were measured. The von Mises stresses in the osteosynthesis material were calculated to predict possible material failure in the plates and screws. In addition, the maximum principal strain in the bone was used to indicate potential bone areas that might be susceptible to bone resorption. All four plate designs (alpha, kappa, rhomboid, and trapezoidal) were tested under the same conditions: a load of 500 N simulating the maximum masticatory force of a healthy adult and a load of 135 N corresponding to the reduced masticatory force within the six postoperative weeks. According to our findings, all four plates showed adequate fixation of neck fractures at a load of 135 N with a risk for delayed screw loosening only when the trapezoidal and rhomboid plates were used. On the other hand, the plates showed significant differences when a load of 500 N was applied. Larger plates requiring more screws for fixation, such as the alpha and kappa plates, performed better than the rhomboid and trapezoidal plates, which have half the volume of the former. The alpha and kappa plates showed higher rigidity and better stress distribution in the bone. The trapezoidal plate resulted in less rigid fixation because the micromovements could lead to pseudoarthrosis. The above results may differ if the course of the fracture line or the position of the plate changes. These parameters were examined in the current study for the relatively new lambda plate, for which there is insufficient data to make any conclusions about its application. The rigidity of osteosynthesis using the lambda plate was studied for a load of 500N. According to the results of the present study, the lambda plate provided adequate rigidity only for neck fractures. In contrast, the stability of osteosynthesis was unsatisfactory for basal fractures. Furthermore, in condylar neck fractures, a more cranial placement of the plate should be pursued. Finally, if the Lambda plate is used for basal fractures, it should be combined with an additional plate under the sigmoid notch. The finite element analysis is a computational method, and results apply only to fracture patterns and osteosynthesis materials simulated with current models. The results should be validated by experimental or clinical studies

Nodal Disease and Survival in Oral Cancer: Is Occult Metastasis a Burden Factor Compared to Preoperatively Nodal Positive Neck?

Simple Summary Occult metastasis in oral squamous cell carcinoma patients is a feared complication. However, there are barely any existing data on survival of patients suffering from occult metastasis. This study aims to compare patients with oral squamous cell carcinoma, considering survival in occult metastases and different treatment approaches. The impact of neck involvement and occult metastasis (OM) in patients with oral squamous cell carcinoma (OSCC) favors an elective neck dissection. However, there are barely any existing data on survival for patients with OM compared with patients with positive lymph nodes detected preoperatively. This study aims to compare survival curves of patients suffering from lymph nodal metastases in a preoperatively N+ neck with those suffering from OM. In addition, clinical characteristics of the primary tumor were analyzed to predict occult nodal disease. This retrospective cohort study includes patients with an OSCC treated surgically with R0 resection with or without adjuvant chemoradiotherapy between 2010 and 2016. Minimum follow-up was 60 months. Kaplan-Meier analysis was used to compare the survival between patients with and without occult metastases and patients with N+ neck to those with occult metastases. Logistic regression was used to detect potential risk factors for occult metastases. The patient cohort consisted of 226 patients. Occult metastases occurred in 16 of 226 patients. In 53 of 226 patients, neck lymph nodes were described as suspect on CT imaging but had a pN0 neck. Higher tumor grading increased the chance of occurrence of occult metastasis 2.7-fold (OR = 2.68, 95% CI: 1.07-6.7). After 12, 24, 48 and 60 months, 82.3%, 73.8%, 69% and 67% of the N0 patients, respectively, were progression free. In the group with OM occurrence, for the same periods 66.6%, 50%, 33.3% and 33.3% of the patients, respectively, were free of disease. For the same periods, respectively, 81%, 63%, 47% and 43% of the patients in the N+ group but without OM remained disease free. The predictors for progression-free survival were a positive N status (HR = 1.44, 95% CI: 1.08-1.93) and the occurrence of OM (HR = 2.33, 95% CI: 1.17-4.64). The presence of occult metastasis could lead to decreased survival and could be a burdening factor requiring treatment escalation and a more aggressive follow-up than nodal disease detected in the preoperative diagnostic imaging

Digital planning and individual implants for secondary reconstruction of midfacial deformities: A pilot study

Objective To evaluate the feasibility and accuracy of implementing three-dimensional virtual surgical planning (VSP) and subsequent transfer by additive manufactured tools in the secondary reconstruction of residual post-traumatic deformities in the midface. Methods Patients after secondary reconstruction of post-traumatic midfacial deformities were included in this case series. The metrical deviation between the virtually planned and postoperative position of patient-specific implants (PSI) and bone segments was measured at corresponding reference points. Further information collected included demographic data, post-traumatic symptoms, and type of transfer tools. Results Eight consecutive patients were enrolled in the study. In five patients, VSP with subsequent manufacturing of combined predrilling/osteotomy guides and PSI was performed. In three patients, osteotomy guides, repositioning guides, and individually prebent plates were used following VSP. The median distances between the virtually planned and the postoperative position of the PSI were 2.01 mm (n = 18) compared to a median distance concerning the bone segments of 3.05 mm (n = 12). In patients where PSI were used, the median displacement of the bone segments was lower (n = 7, median 2.77 mm) than in the group with prebent plates (n = 5, 3.28 mm). Conclusion This study demonstrated the feasibility of VSP and transfer by additive manufactured tools for the secondary reconstruction of complex residual post-traumatic deformities in the midface. However, the median deviations observed in this case series were unexpectedly high. The use of navigational systems may further improve the level of accuracy

Postoperative Delirium in Patients with Oral Cancer: Is Intraoperative Fluid Administration a Neglected Risk Factor?

Squamous cell carcinoma (SCC) is a malignant tumor derived from squamous cells and can be found in different localizations. In the oral cavity especially, it represents the most common type of malignant tumor. First-line therapy for oral squamous cell carcinoma (OSCC) is surgery, including tumor resection, neck dissection, and maybe reconstruction. Although perioperative mortality is low, complications such as delirium are very common, and may have long-lasting consequences on the patient’s quality of life. This study examines if excessive fluid administration, among other parameters, is an aggravating factor for the development of postoperative delirium. A total of 198 patients were divided into groups concerning the reconstruction technique used: group A for primary wound closure or reconstruction with a local flap, and group B for microsurgical reconstruction. The patients with and without delirium in both groups were compared regarding intraoperative fluid administration, fluid balance, and other parameters, such as blood loss, duration of surgery and overall ventilation, alcohol consumption, and creatinine, albumin, natrium, and hematocrit levels. The logistic regression for group A shows that fluid intake (p = 0.02, OR = 5.27, 95% CI 1.27–21.8) and albumin levels (p = 0.036, OR = 0.22, CI 0.054–0.908) are independent predictors for the development of delirium. For group B, gender (p = 0.026, OR = 0.34, CI 0.133–0.879) with a protective effect for females, fluid intake (p = 0.003, OR = 3.975, CI 1.606–9.839), and duration of ventilation (p = 0.025, OR = 1.178, CI 1.021–1.359) are also independent predictors for delirium. An intake of more than 3000 mL for group A, and 4150 mL for group B, increases the risk of delirium by approximately five and four times, respectively. Fluid management should be considered carefully in patients with OSCC, in order to reduce the occurrence of postoperative delirium. Different factors may become significant for the development of delirium regarding different surgical procedures

Cancer testis antigen (PRAME) as an independent marker for survival in oral squamous cell carcinoma (OSCC)

Background The objective was to assess the expression patterns of the cancer testis antigen PRAME, NY-ESO1, and SSX2 in oral squamous cell carcinoma (OSSC) and to correlate the expression with clinical and histopathological parameters including progression-free survival analysis. Methods The study variables of this retrospective cohort study (n = 83) included demographic data, histopathological data, and information on progression-free survival. PRAME expression patterns were rated based on immunohistochemistry on tissue microarrays (TMA). The survival rate was assessed by Kaplan-Meier method and Cox regression model. The primary predictor variable was defined as the expression of PRAME and the outcome variable was progression-free survival. Results Analysis of progression-free survival using Kaplan-Meier method showed that patients with positive expression of PRAME had lower probabilities of progression-free survival (p < 0.001). According to the Cox regression model, the level of PRAME expression had a considerable and significant independent influence on progression-free survival (positive PRAME expression increasing the hazards for a negative outcome by 285% in our sample;HR = 3.85, 95% CI: 1.45-10.2, p = 0.007). The expression of SSX2 (n = 1) and NY-ESO-1 (n = 5) in our samples was rare. Conclusion PRAME is expressed in OSCC and appears to be a suitable marker of progression-free survival, correlates with severe course, and may allow identification of high-risk patients with aggressive progression