Computer-Assisted Navigation in Craniomaxillofacial Tumors

Virtual tumor mapping and margin control with 3-D planning and navigation

Computer technology-based treatment approaches like intraoperative navigation and intensity-modulated radiation therapy have become important components of state of the art head and neck cancer treatment. Multidirectional exchange of virtual three-dimensional patient data via an interdisciplinary platform allows all medical specialists involved in the patients treatment to take full advantage of these technologies. This review article gives an overview of current technologies and future directions regarding treatment approaches that are based on a virtual, three-dimensional patient specific dataset: storage and exchange of spatial information acquired via intraoperative navigation allow for a highly precise frozen section procedure. In the postoperative setting, virtual reconstruction of the tumor resection surface provides the basis for improved radiation therapy planning and virtual reconstruction of the tumor with integration of molecular findings creates a valuable tool for postoperative treatment and follow-up. These refinements of established treatment components and novel approaches have the potential to make a major contribution to improving the outcome in head and neck cancer patients.

Exploring Deep Cervical Compartments in Head and Neck Surgical Oncology through Augmented Reality Vision: A Proof of Concept

BACKGROUND

Virtual surgical planning allows surgeons to meticulously define surgical procedures by creating a digital replica of patients' anatomy. This enables precise preoperative assessment, facilitating the selection of optimal surgical approaches and the customization of treatment plans. In neck surgery, virtual planning has been significantly underreported compared to craniofacial surgery, due to a multitude of factors, including the predominance of soft tissues, the unavailability of intraoperative navigation and the complexity of segmenting such areas. Augmented reality represents the most innovative approach to translate virtual planning for real patients, as it merges the digital world with the surgical field in real time. Surgeons can access patient-specific data directly within their field of view, through dedicated visors. In head and neck surgical oncology, augmented reality systems overlay critical anatomical information onto the surgeon's visual field. This aids in locating and preserving vital structures, such as nerves and blood vessels, during complex procedures. In this paper, the authors examine a series of patients undergoing complex neck surgical oncology procedures with prior virtual surgical planning analysis. For each patient, the surgical plan was imported in Hololens headset to allow for intraoperative augmented reality visualization. The authors discuss the results of this preliminary investigation, tracing the conceptual framework for an increasing AR implementation in complex head and neck surgical oncology procedures.

Navigation-guided resection of locally advanced midface malignancies. Does it improve the safety of oncologic resection?

INTRODUCTION

Treatment of malignant midface tumors is a surgical challenge with an increased difficulty to obtain free surgical margins. The computer assisted surgery (CAS) and intraoperative navigation (ION) can be very helpful in complex midface resections. The main objective of this paper is to evaluate if the ION could improve the rate of free surgical margins in locally advanced midface malignancies.

MATERIALS AND METHODS

A retrospective cohort study was performed including 40 patients with a locally advanced malignant midface tumor (T4a/b) surgically treated from September 2016 to September 2022. Patients were divided in two groups, a control group included 20 patients operated on without ION and the study group included 20 patients treated with Navigation assisted surgery. A systematic analysis was performed comparing surgical margins in both groups.

RESULTS

Squamous cell carcinoma was the most common histological type. Oral cavity was the most common primary location. Overall, considering each specimen as an hexahedrium, 240 surgical margins were analyzed. 15 out of 120 margins analyzed in the navigation group (12.5 %) were positive while 30 out of 120 margins analyzed in control group (25 %) were affected (p 0.013). Concerning margin location, the ION group showed less involvement of the upper surface of specimen than in control group (p 0.048).

CONCLUSION

Navigation Assisted Surgery seems to improve the rate of free surgical margins in patients with locally advanced midface malignancies, specially concerning involvement of the superior margin. Further studies are recommended to corroborate these results and its potential influence in survival rates.

Skull-Base Surgery—A Narrative Review on Current Approaches and Future Developments in Surgical Navigation

Surgical navigation technology combines patient imaging studies with intraoperative real-time data to improve surgical precision and patient outcomes. The navigation workflow can also include preoperative planning, which can reliably simulate the intended resection and reconstruction. The advantage of this approach in skull-base surgery is that it guides access into a complex three-dimensional area and orients tumors intraoperatively with regard to critical structures, such as the orbit, carotid artery and brain. This enhances a surgeon’s capabilities to preserve normal anatomy while resecting tumors with adequate margins. The aim of this narrative review is to outline the state of the art and the future directions of surgical navigation in the skull base, focusing on the advantages and pitfalls of this technique. We will also present our group experience in this field, within the frame of the current research trends.

A novel motionless calibration method for augmented reality surgery navigation system based on optical tracker

Augmented reality (AR) surgery navigation systems display the pre-operation planned virtual model at the accurate position in the real surgical scene to assist the operation. Accurate calibration of the mapping relationship between the virtual coordinate and the real world is the key to the virtual-real fusion effect. Former calibration methods require the doctor user to conduct complex manual procedures before usage. This paper introduces a novel motionless virtual-real calibration method. The method only requires to take a mixed reality image containing both virtual and real marker balls using the built-in forward camera of the AR glasses. The mapping relationship between the virtual and real spaces is calculated by using the camera coordinate system as a transformation medium. The composition and working process of the AR navigation system is introduced, and then the mathematical principle of the calibration is designed. The feasibility of the proposed calibration scheme is verified with a verification experiment, and the average registration accuracy of the scheme is around 5.80mm, which is of same level of formerly reported methods. The proposed method is convenient and rapid to implement, and the calibration accuracy is not dependent on the user experience. Further, it can potentially realize the real-time update of the registration transformation matrix, which can improve the AR fusion accuracy when the AR glasses moves. This motionless calibration method has great potential to be applied in future clinical navigation research.

[Current Therapy Standards for Soft Tissue Sarcomas in the Head and Neck Area - Part 2]

In September 2021, the first version of the German S3 guideline on adult soft tissue sarcomas, version 1.0 (AWMF register number 032/044OL) was presented as part of the oncology guideline program of the DKG, German Cancer Aid and the AWMF. After the basic features of soft tissue sarcomas were presented in Part 1, Part 2 describes the specific options for surgical therapy depending on the location in the head and neck area.

Primary Orbital Reconstruction with Selective Laser Melting (SLM) of Patient-Specific Implants (PSIs): An Overview of 96 Surgically Treated Patients

Contemporary advances in technology have allowed the transfer of knowledge from industrial laser melting systems to surgery; such an approach could increase the degree of accuracy in orbital restoration. The aim of this study was to examine the accuracy of selective laser melted PSIs (patient-specific implants) and navigation in primary orbital reconstruction. Ninety-six patients with orbital fractures were included in this study. Planned vs. achieved orbital volumes (a) and angles (b) were compared to the unaffected side (n = 96). The analysis included the overlay of post-treatment on planned images (iPlan 3.0.5, Brainlab®, Feldkirchen, Germany). The mean difference in orbital volume between the digitally planned orbit and the postoperative orbit was 29.16 cm3 (SD 3.54, presurgical) to 28.33 cm3 (SD 3.64, postsurgical, t = 5.00, df = 95.00; p < 0.001), resulting in a mean volume difference (planned vs. postop) of less than 1 cm3. A 3D analysis of the color mapping showed minor deviations compared to the mirrored unaffected side. The results suggested that primary reconstruction in complex orbital wall fractures can be routinely achieved with a high degree of accuracy by using selective laser melted orbital PSIs.

Computer‐assisted and navigated piezoelectric surgery: A new technology to improve precision and surgical safety in craniomaxillofacial surgery

Background

Computer‐assisted navigated piezoelectric surgery (CANPS) is a surgical technique that combines the surgical navigation with a piezoelectric device. This association multiplies the advantages of both technologies, taking the best of each one providing a synergistic association.

Objective

To describe and assess the indications, advantages, disadvantages, and complications of this association of surgical techniques.

Methods

CANPS was used in 32 patients. The clinical diagnosis was facial trauma, tumors, orthognathic surgeries, temporomandibular joint ankylosis, pathology of the frontal sinus, and alveolar distraction. Nineteen patients were men and 13 were women. Planning software iPlan 3.05 of Brainlab, and Elements of Brainlab were used for planning and the Kolibri and Kurve of Brainlab for surgical navigation. The piezoelectric device used was a “Vercelotti” type in all patients.

Results

CAPNS could be performed successfully in all cases without complications and reduced the surgeon's uncertainty during the osteotomies. There is continuous control of the position of the surgical instrument. The use of the navigated piezoelectric device allowed the surgeon's uncertainty to be reduced during the performance of the osteotomies in depth, in poorly visible areas, with little access or reduced visibility. It also increases the safety of bone resections near important anatomical structures.

Conclusions

CANPS combines the advantages of piezoelectric surgery and navigation. CANPS affords real‐time control of the position of the cutting tip and allows semiburied approaches. CANPS allows surgery to be precise, safer, and minimally invasive.

Navigation-Guided Transnasal Endoscopic Delineation of the Posterior Margin for Maxillary Sinus Cancers: A Preclinical Study

Background

The resection of advanced maxillary sinus cancers can be challenging due to the anatomical proximity to surrounding critical anatomical structures. Transnasal endoscopy can effectively aid the delineation of the posterior margin of resection. Implementation with 3D-rendered surgical navigation with virtual endoscopy (3D-SNVE) may represent a step forward. This study aimed to demonstrate and quantify the benefits of this technology.

Material and Method

Four maxillary tumor models with critical posterior extension were created in four artificial skulls (Sawbones^®). Images were acquired with cone-beam computed tomography and the tumor and carotid were contoured. Eight head and neck surgeons were recruited for the simulations. Surgeons delineated the posterior margin of resection through a transnasal approach and avoided the carotid while establishing an adequate resection margin with respect to tumor extirpation. Three simulations were performed: 1) unguided: based on a pre-simulation study of cross-sectional imaging; 2) tumor-guided: guided by real-time tool tracking with 3D tumor and carotid rendering; 3) carotid-guided: tumor-guided with a 2-mm alert cloud surrounding the carotid. Distances of the planes from the carotid and tumor were classified as follows and the points of the plane were classified accordingly: “red”: through the carotid artery; “orange”: <2 mm from the carotid; “yellow”: >2 mm from the carotid and within the tumor or <5 mm from the tumor; “green”: >2 mm from the carotid and 5–10 mm from the tumor; and “blue”: >2 mm from the carotid and >10 mm from the tumor. The three techniques (unguided, tumor-guided, and carotid-guided) were compared.

Results

3D-SNVE for the transnasal delineation of the posterior margin in maxillary tumor models significantly improved the rate of margin-negative clearance around the tumor and reduced damage to the carotid artery. “Green” cuts occurred in 52.4% in the unguided setting versus 62.1% and 64.9% in the tumor- and carotid-guided settings, respectively (p < 0.0001). “Red” cuts occurred 6.7% of the time in the unguided setting versus 0.9% and 1.0% in the tumor- and carotid-guided settings, respectively (p < 0.0001).

Conclusions

This preclinical study has demonstrated that 3D-SNVE provides a substantial improvement of the posterior margin delineation in terms of safety and oncological adequacy. Translation into the clinical setting, with a meticulous assessment of the oncological outcomes, will be the proposed next step.

Advances in the Resection and Reconstruction of Midfacial Tumors Through Computer Assisted Surgery

Curatively intended oncologic surgery is based on a residual-free tumor excision. Since decades, the surgeon’s goal of R0-resection has led to radical resections in the anatomical region of the midface because of the three-dimensionally complex anatomy where aesthetically and functionally crucial structures are in close relation. In some cases, this implied aggressive overtreatment with loss of the eye globe. In contrast, undertreatment followed by repeated re-resections can also not be an option. Therefore, the evaluation of the true three-dimensional tumor extent and the intraoperative availability of this information seem critical for a precise, yet substance-sparing tumor removal. Computer assisted surgery (CAS) can provide the framework in this context. The present study evaluated the beneficial use of CAS in the treatment of midfacial tumors with special regard to tumor resection and reconstruction. Therefore, 60 patients diagnosed with a malignancy of the upper jaw has been treated, 31 with the use of CAS and 29 conventionally. Comparison of the two groups showed a higher rate of residual-free resections in cases of CAS application. Furthermore, we demonstrate the use of navigated specimen taking called tumor mapping. This procedure enables the transparent, yet precise documentation of three-dimensional tumor borders which paves the way to a more feasible interdisciplinary exchange leading e.g. to a much more focused radiation therapy. Moreover, we evaluated the possibilities of primary midface reconstructions seizing CAS, especially in cases of infiltrated orbital floors. These cases needed reduction of intra-orbital volume due to the tissue loss after resection which could be precisely achieved by CAS. These benefits of CAS in midface reconstruction found expression in positive changes in quality of life. The present work was able to demonstrate that the area of oncological surgery of the midface is a prime example of interface optimization based on the sensible use of computer assistance. The fact that the system makes the patient transparent for the surgeon and the procedure controllable facilitates a more precise and safer treatment oriented to a better outcome.

Interdisciplinary management of skull base surgery

Skull base surgery remains one of the challenging areas in the field of cranio-maxillofacial surgery, otolaryngology and neurosurgery. Subsequent reconstruction of bone and soft tissue are an essential component to restore function and appearance after ablative surgery. Establishment of interdisciplinary tumor boards with presentation of the individual patient cases have become standard. Multiplanar reconstruction using MRI or CT imaging techniques combined with virtual 3D planning allow precise planning of the procedures. Intraoperative navigation helps for complete resection of malignant findings with safety margins; surgical approaches provide a good overview of the surgical site. Reconstruction using local flaps have a low complication rate with equally reliable results in reconstruction of small tissue defects. Free flap surgery makes reconstruction of large tissue defects possible. Alloplastic materials are alternatively used for reconstruction of bone defects. Based on selected patients, treatment algorithms and standard surgical procedures in extracerebral skull base surgery will be illustrated. Current techniques and new approaches will be discussed with emphasize on hard and soft tissue reconstruction.

Role of Navigation in Oral and Maxillofacial Surgery: A Surgeon's Perspectives

Surgeries related to the maxillofacial area deal with an intricate network of anatomical structures. With the complexity of the vital structures, it necessitates a surgical team to respect each anatomical boundary. In the past, there was an exceptionally high number of cases with surgical errors. These errors were not because of flaws in the surgeon’s skills or techniques but owing to lack of resources. Visualisation is one of the key factors that determines the precision of any surgical outcome. Advances in surgical planning have led to the introduction of a “Navigation” system that helps surgeons to see more, know more and ultimately do more for their patients. The usefulness of the navigation system in oral surgeries has been indicated by its surgical applications in craniomaxillofacial trauma, orthognathic surgeries, head and neck pathological resections, complex skull base surgeries and surgery involving temporomandibular joint. A vast majority of research literature has suggested remarkable improvement in surgical outcomes under the guidance of 3d planning and navigation. However, with such an inordinate advancement, financial expenses and a gradual learning curve are always a constraining factor in surgical navigation. This article overviews indication of navigation in craniofacial surgeries with a focus on applied aspect, planning and solution to the future problem.

The Wearable VOSTARS System for Augmented Reality-Guided Surgery: Preclinical Phantom Evaluation for High-Precision Maxillofacial Tasks

BACKGROUND

In the context of guided surgery, augmented reality (AR) represents a groundbreaking improvement. The Video and Optical See-Through Augmented Reality Surgical System (VOSTARS) is a new AR wearable head-mounted display (HMD), recently developed as an advanced navigation tool for maxillofacial and plastic surgery and other non-endoscopic surgeries. In this study, we report results of phantom tests with VOSTARS aimed to evaluate its feasibility and accuracy in performing maxillofacial surgical tasks.

METHODS

An early prototype of VOSTARS was used. Le Fort 1 osteotomy was selected as the experimental task to be performed under VOSTARS guidance. A dedicated set-up was prepared, including the design of a maxillofacial phantom, an ad hoc tracker anchored to the occlusal splint, and cutting templates for accuracy assessment. Both qualitative and quantitative assessments were carried out.

RESULTS

VOSTARS, used in combination with the designed maxilla tracker, showed excellent tracking robustness under operating room lighting. Accuracy tests showed that 100% of Le Fort 1 trajectories were traced with an accuracy of ±1.0 mm, and on average, 88% of the trajectory's length was within ±0.5 mm accuracy.

CONCLUSIONS

Our preliminary results suggest that the VOSTARS system can be a feasible and accurate solution for guiding maxillofacial surgical tasks, paving the way to its validation in clinical trials and for a wide spectrum of maxillofacial applications.

Navigation-guided osteotomies improve margin delineation in tumors involving the sinonasal area: A preclinical study

OBJECTIVES

To demonstrate and quantify, in a preclinical setting, the benefit of three-dimensional (3D) navigation guidance for margin delineation during ablative open surgery for advanced sinonasal cancer.

MATERIALS AND METHODS

Seven tumor models were created. 3D images were acquired with cone beam computed tomography, and 3D tumor segmentations were contoured. Eight surgeons with variable experience were recruited for the simulation of osteotomies. Three simulations were performed: 1) Unguided, 2) Guided using real-time tool tracking with 3D tumor segmentation (tumor-guided), and 3) Guided by 3D visualization of both the tumor and 1-cm margin segmentations (margin-guided). Analysis of cutting planes was performed and distance from the tumor surface was classified as follows: "intratumoral" when 0 mm or negative, "close" when greater than 0 mm and less than or equal to 5 mm, "adequate" when greater than 5 mm and less than or equal to 15 mm, and "excessive" over 15 mm. The three techniques (unguided, tumor-guided, margin-guided) were statistically compared.

RESULTS

The use of 3D navigation for margin delineation significantly improved control of margins: unguided cuts had 18.1% intratumoral cuts compared to 0% intratumoral cuts with 3D navigation (p < 0.0001).

CONCLUSION

This preclinical study has demonstrated the significant benefit of navigation-guided osteotomies for sinonasal tumors. Translation into the clinical setting - with rigorous assessment of oncological outcomes - would be the proposed next step.

Supporting fibula free flap harvest with augmented reality: A proof-of-concept study

OBJECTIVE

To analyze a novel navigation system utilizing augmented reality (AR) as a supporting method for fibula free flap (FFF) harvest and fabrication.

METHODS

A total of 126 simulated osteotomies supported with a cutting guide or one of two AR-based intraoperative navigation modules-simple AR (sAR) or navigated AR (nAR)-were carried out on 18 identical models of the fibula (42 osteotomies per method). After fusing postoperative computed tomography scans of the operated fibulas with the virtual surgical plan based on preoperative images, the objective outcomes-angular deviations from the planned osteotomy trajectory (^o ) and deviations of control points marked on the trajectory (mm)-were determined.

RESULTS

All analyzed methods provided similar accuracy of assisted osteotomies. The only significant difference referred to angular deviation in the sagittal plane, which was smaller after the cutting guide-assisted procedures than after the application of sAR and nAR (4.1 ± 2.29 vs. 5.08 ± 3.64 degrees, P = 0.031 and 4.1 ± 2.29 vs. 4.97 ± 2.91, P = 0.002, respectively). Mean deviation of control points after the cutting guide-assisted procedures was 2.76 ± 1.06 mm, as compared with 2.67 ± 1.09 mm for sAR and 2.95 ± 1.11 mm for nAR.

CONCLUSION

Our study demonstrated that both novel AR-based methods provided similar accuracy of assisted harvesting and contouring of the FFF as the cutting guides. This fact, as well as the acceptability of the concept by clinicians, justify their further development and evaluation in preclinical settings.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:1173-1179, 2020.

Navigation-guided resection of maxillary tumors: Can a new volumetric virtual planning method improve outcomes in terms of control of resection margins?

INTRODUCTION

In the present study, our aim was to confirm the role of navigation-guided surgery in reducing the percentage of positive margins in advanced malignant pathologies of the mid-face, by introducing a new volumetric virtual planning method for resection.

MATERIALS AND METHODS

Twenty-eight patients were included in this study. Eighteen patients requiring surgery to treat malignant midface tumors were prospectively selected and stratified into two different study groups. Patients enrolled in the Reference Points Resection group (RPR - 10 patients) underwent resection planning using the anatomical landmarks on CT scan; patients enrolled in the Volume Resection group (VR - 8 patients) underwent resection using the new volumetric virtual planning method. The remaining 10 patients (Control group) were treated without the use of a navigation system.

RESULTS

In total, 127 margins were pathologically assessed in the RPR group, 75 in the VR group, and 85 in the control group. In the control group, 16% of the margins were positive, while in the RPR group the value was 9%, and in the VR group 1%.

CONCLUSIONS

The volumetric tumor resection planning associated to the navigation-guide resection appeared to be an improvement in terms of control of surgical margins in advanced tumors involving the mid-face.

A novel approach to skull-base and orbital osteotomies through virtual planning and navigation

OBJECTIVE

Computer-assisted planning of osteotomy lines, coupled with navigation-guided performance of planned osteotomies, is a highly innovative approach to skull-base and orbital surgery. The aim of this pilot study is to provide an assessment of the accuracy of this novel approach in guiding the correct positioning of osteotomy lines in frontal, temporal, and orbital regions, defining the agreement between the spatial position of the planned and performed osteotomies.

METHODS

Fifteen patients with orbital, frontal sinus, and lateral skull-base diseases underwent virtual surgical planning. Osteotomies to access the orbit, frontal sinus, and lateral skull base were planned on computer tomography-based three-dimensional models. The planned osteotomies were reproduced on the operating field using a navigation system. The positions of the performed and planned osteotomies were compared. The results were described as the mean positional difference between planned and performed osteotomies and as Lin's concordance coefficient, and Bland-Altman limits of agreement were also defined.

RESULTS

The overall mean difference was 0.719 mm (95% confidence interval [CI]: 0.472 to 0.965 mm). Overall, Lin's concordance coefficient was 0.997 (95% CI: 0.996 to 0.998), and overall Bland-Altman limits of agreement ranged from -1.407 to 2.844 mm. The smallest mean difference (0.587 mm, 95% CI: 0.244 to 0.931 mm) was calculated in the orbit group, whereas the highest mean difference (0.904 mm, 95% CI: 0.428 to 1.379 mm) was described in the lateral skull-base group.

CONCLUSION

This study's results support the use of this novel planning and navigation protocol for guiding osteotomy in anterior and lateral skull-base surgery, providing a clinical validation of this technique.

LEVEL OF EVIDENCE

4 Laryngoscope, 00:1-9, 2018 Laryngoscope, 129:823-831, 2019.

Use of Technological Aids in the Resection of a Rare Maxillofacial Tumor of Infancy

Melanotic neuroectodermal tumor of infancy is a rare maxillofacial tumor, usually presenting within the first year of life, often a benign locally aggressive lesion, with wide local excision providing the best opportunity of cure. In past reports, direct tissue visualization guided resection, with occasional need for reoperation to clear margins. In this case report, a method is presented to achieve clear margins in surgery using virtual surgical planning and surgical stealth navigation.

Navigation-guided resection of maxillary tumours: The accuracy of computer-assisted surgery in terms of control of resection margins - A feasibility study

INTRODUCTION

Surgical treatment of maxillary tumours is often highly complex. The three-dimensional anatomy of the mid-face renders both correct intraoperative orientation and adequate oncological safety difficult to obtain. Recently, computer-assisted techniques and intraoperative navigation have been applied to oncological surgery treating head and neck cancer. However, only a few studies have explored whether preoperative virtual resection planning and intraoperative control of resection margins allow assessment of the surgical margins of the tumour. In our present feasibility study, we developed a protocol for preoperative mapping of tumour margins using computed tomography and/or magnetic resonance imaging, virtual planning of the surgical resection, and intraoperative navigation during actual resection of advanced maxillary tumours.

MATERIALS AND METHODS

Twenty patients were included in this feasibility study. We prospectively selected ten patients requiring surgery to treat malignant maxillary tumours. A control group of ten patients was retrospectively selected. The simulation protocol featured the following steps: 1. "Contouring" of the tumour: identification of the tumour and the borders thereof on the axial, sagittal, and coronal planes; 2. Definition of the resection margins by positioning "landmarks" at least 1 cm from the tumour edges on the axial, sagittal, and coronal planes; 3. Simulation of osteotomy lines passing through the landmarks, and evaluation of the bony defects to be reconstructed. Tumour margins were controlled by using a pointer to identify mobilised regions and then checking the overlap between the planned resection (shown on the LCD screen of the navigation system) and the real anatomical situation.

RESULTS

A total of 127 margins were pathologically assessed in the test group, and 85 were assessed in the control group. Overall, 9% of surgical margins were positive in the test group, and 16% were positive in the control group (p = 0.0047). A significant difference was apparent in terms of deep margin evaluation: in test patients, 87% of margins were clear; this figure was 75% for the control group (p = 0.0038). No significant difference in either mucosal or bone margin clearance was evident. The preoperative planning errors were <5 mm for 91% of all planned resection margins.

CONCLUSION

The navigation-guided resection protocol seems to improve tumour-free margin status in patients with advanced maxillary tumours. Further confirmatory trial, enrolling a larger cohort of patients, is needed to strengthen these preliminary results and advantages of this procedure.

Surgical Navigation: A Systematic Review of Indications, Treatments, and Outcomes in Oral and Maxillofacial Surgery

PURPOSE

This systematic review investigates the most common indications, treatments, and outcomes of surgical navigation (SN) published from 2010 to 2015. The evolution of SN and its application in oral and maxillofacial surgery have rapidly developed over recent years, and therapeutic indications are discussed.

MATERIALS AND METHODS

A systematic search in relevant electronic databases, journals, and bibliographies of the included articles was carried out. Clinical studies with 5 or more patients published between 2010 and 2015 were included. Traumatology, orthognathic surgery, cancer and reconstruction surgery, skull-base surgery, and foreign body removal were the areas of interests.

RESULTS

The search generated 13 articles dealing with traumatology; 5, 6, 2, and 0 studies were found that dealt with the topics of orthognathic surgery, cancer and reconstruction surgery, skull-base surgery, and foreign body removal, respectively. The average technical system accuracy and intraoperative precision reported were less than 1 mm and 1 to 2 mm, respectively. In general, SN is reported to be a useful tool for surgical planning, execution, evaluation, and research. The largest numbers of studies and patients were identified in the field of traumatology. Treatment of complex orbital fractures was considerably improved by the use of SN compared with traditionally treated control groups.

CONCLUSIONS

SN seems to be a very promising addition to the surgical toolkit. Planning details of the surgical procedure in a 3-dimensional virtual environment and execution with real-time guidance can significantly improve precision. Among factors to be considered are the financial investments necessary and the learning curve.

Intraoperative navigation in complex head and neck resections: indications and limits

PURPOSE

The surgical removal of head and neck tumors often represents a highly complex surgery. The three-dimensionality and the anatomy of the head and neck area make sometimes difficult a correct intraoperative orientation and the obtaining of an adequate oncological safety. In the present pilot study, the authors propose a protocol of application of intraoperative navigation in the resection of head and neck tumors. The purpose is to develop a methodology that can be helpful to ensure oncologic free margins of resection and to facilitate the orientation of the specimen by pathologists.

MATERIALS AND METHODS

A sample of 16 patients with head and neck tumors was selected, and they were differentiated into two groups: a "study group" treated with CT computer-assisted surgery and a "control group" surgically treated without the use of technology. The following data were analyzed: operative and pre-surgical planning times, issues related to the use of the technologies, respect of the planned landmarks, description and orientation of the surgical specimen and distance of the tumor from the margins of resection.

RESULTS

In the "study group" were noticed a reduced rate of errors in the specimen orientation and an increased distance of the tumor from the margins of resection. Similar operative times were observed in both groups.

CONCLUSIONS

Intraoperative navigation resulted to be a reliable method to improve oncological safety in a selected group of patients.

Piezoelectric surgery and navigation: a safe approach for complex cases of Eagle syndrome

Eagle syndrome was first described by Eagle in 1937. It is associated with an elongated styloid process and/or calcification of the stylohyoid ligament, mainly resulting in pain in the orofacial region. The treatment of Eagle syndrome includes conservative treatment with physical therapy supported by medication, or surgical removal of the styloid process. Two different surgical approaches are described in the literature: the transoral and transcervical approaches. Both have their limitations and specific intraoperative risks. A modification of the transcervical approach that adds an extra security measure to the treatment of complex cases of Eagle syndrome is presented herein. The styloid process was removed by combining piezoelectric surgery, preoperative digital planning, and surgical navigation. No complication was noted, and the patient recovered quickly after surgery. A follow-up visit 2 months later showed no remaining symptoms of Eagle syndrome on the treated side. Therefore, digital planning and surgical navigation could add valuable safety measures to the treatment of complex cases of Eagle syndrome.

A Revised Approach for Mandibular Reconstruction With the Vascularized Iliac Crest Flap Using Virtual Surgical Planning and Surgical Navigation

PURPOSE

The purpose of this study was to describe a revised approach for mandibular reconstruction with vascularized iliac crest flap using virtual surgical planning and surgical navigation.

PATIENTS AND METHODS

Preoperative maxillofacial and iliac non-contrast-enhanced computed tomography (CT) scans were acquired, and CT data were imported into ProPlan CMF software (Materialise, Leuven, Belgium). We performed virtual mandibulectomy and superimposed the 3-dimensional iliac image on the mandibular defect. The surgeon shaped the iliac flap according to virtual parameters and the stereomodel. Surgical navigation was used to check and correct the shaped segments. The position of the osteotomy lines and relevant parameters regarding the shape of the iliac flap also were provided to the surgeon. After computer simulation, a reconstructed mandibular stereomodel was manufactured. A reconstruction plate was prebent and fixed on this model using titanium screws. The model was scanned, data were imported into ProPlan CMF, the mandible was segmented, and data were imported into the intraoperative navigation system. Then, the model was registered with the original CT data, and the reconstruction plate was eliminated. Navigation data were exported into a universal serial bus drive, which was connected to the terminal working station during surgery. Intraoperative navigation was used to implement the virtual plan for patients. The sagittal, coronal, axial, and 3-dimensional reconstruction images displayed by the navigation system were used to accurately determine the osteotomy sites and osteotomy trajectory during surgery. Surgical probe guidance was used to mark the osteotomy line and transfer the virtual procedure to real-time surgery.

RESULTS

Using our method, we precisely recovered the original configuration of the mandible. The shift in the reconstructed mandible and plate was less than 5 mm.

CONCLUSIONS

We provided a new method for mandibular reconstruction with vascularized iliac crest flap and an individual reconstruction plate using computer-assisted techniques involving surgical navigation, which have the potential to improve the clinical outcomes of this procedure.

Image-guided bone resection as a prospective alternative to cutting templates—A preliminary study

OBJECTIVE

To evaluate the accuracy of craniomaxillofacial resections performed with an image-guided surgical sagittal saw.

MATERIAL AND METHODS

Twenty-four craniomaxillofacial resections were performed using an image-guided sagittal saw. Surgical outcomes were compared with a preoperative virtual plan in terms of the resected bone volume, control point position and osteotomy trajectory angle. Each measurement was performed twice by two independent observers.

RESULTS

The best convergence between the planned and actual bone resection was observed for the orbital region (6.33 ± 4.04%). The smallest mean difference between the preoperative and postoperative control point positions (2.00 ± 0.66 mm) and the lowest mean angular deviation between the virtual and actual osteotomy (5.49 ± 3.17 degrees) were documented for the maxillary region. When all the performed procedures were analyzed together, mean difference between the planned and actual bone resection volumes was 9.48 ± 4.91%, mean difference between the preoperative and postoperative control point positions amounted to 2.59 ± 1.41 mm, and mean angular deviation between the planned and actual osteotomy trajectory equaled 8.21 ± 5.69 degrees.

CONCLUSION

The results of this study are encouraging but not fully satisfactory. If further improved, the hereby presented navigation technique may become a valuable supporting method for craniomaxillofacial resections.

Optimization of the interface between radiology, surgery, radiotherapy, and pathology in head and neck tumor surgery: a navigation-assisted multidisciplinary network

A navigation-assisted multidisciplinary network to improve the interface between radiology, surgery, radiotherapy, and pathology in the field of head and neck cancer is described. All implicated fields are integrated by a common server platform and have remote data access in a ready-to-use format. The margins of resection and exact locations of biopsies are mapped intraoperatively. The pathologist uses the numerical coordinates of these samples to precisely trace each specimen in the anatomical field. Subsequently, map-guided radiotherapy is planned. In addition to the benefits of image-guided resection, this model enables radiotherapy planning according to the specific coordinates of the resection defect plus any residually affected sites identified by the pathologist. Irradiation of adjacent healthy structures is thereby minimized. In summary, the navigation-assisted network described grants timely multidisciplinary feedback between all fields involved, attains meticulous pathological definition, and permits optimized coordinate-directed radiotherapy.

Virtual 3D tumor marking-exact intraoperative coordinate mapping improve post-operative radiotherapy

The quality of the interdisciplinary interface in oncological treatment between surgery, pathology and radiotherapy is mainly dependent on reliable anatomical three-dimensional (3D) allocation of specimen and their context sensitive interpretation which defines further treatment protocols. Computer-assisted preoperative planning (CAPP) allows for outlining macroscopical tumor size and margins. A new technique facilitates the 3D virtual marking and mapping of frozen sections and resection margins or important surgical intraoperative information. These data could be stored in DICOM format (Digital Imaging and Communication in Medicine) in terms of augmented reality and transferred to communicate patient's specific tumor information (invasion to vessels and nerves, non-resectable tumor) to oncologists, radiotherapists and pathologists.

Reconstruction of defects of maxillary sinus wall after removal of a huge odontogenic lesion using prebended 3D titanium-mesh and CAD/CAM technique

A 63 year-old male with a huge odontogenic lesion of sinus maxillaris was treated with computer-assisted surgery. After resection of the odontogenic lesion, the sinus wall was reconstructed with a prebended 3D titanium-mesh using CAD/CAM technique. This work provides a new treatment device for maxillary reconstruction via rapid prototyping procedures.