Improving the accuracy of mandibular reconstruction with vascularized iliac crest flap: Role of computer-assisted techniques

Evaluating the benefit of virtual surgical planning on bony union rates in head and neck reconstructive surgery

OBJECTIVES

Virtual surgical planning (VSP) has gained acceptance because of its benefits in obtaining adequate resection, achieving cephalometric accuracy, and reducing operative time. The aim of this study is to compare the rate of union between VSP and free-hand surgery (FHS), identify predictors of non-union and evaluate the difference in operative time.

METHODS

Post-operative CT were retrospectively reviewed for 123 patients who underwent maxillary or mandibular reconstruction between 2014 and 2021 using either VSP or FHS. Each apposition was graded as complete, partial or non-union. The rate of union, risk difference and inter-rater reliability were calculated. The difference in operative time was assessed. Predictors of non-union were identified using logistic regression.

RESULTS

A total of 326 appositions were graded (VSP n = 150; FHS n = 176). The rates of complete and partial union were higher with VSP than FHS (74.7% vs. 65.3%; 18% vs. 15.9%, respectively, p = 0.01). Non-union was found at a higher rate with FHS than with VSP (18.7% vs. 7.3%). The non-union risk difference was 11.4. FHS, major complications and apposition at the native bone were predictors of non-union (OR 2.9, p = 0.02; OR 3.4, p = 0.01; OR 2.5, p = 0.05, respectively). The mean surgical time was shorter with VSP than with FHS (265.3 vs. 381.5 min, p < 0.001). The inter-rater agreement was high (k = 0.85; ICC = 0.86).

CONCLUSION

VSP demonstrated significantly higher bony union rates and shorter operative time. FHS, development of major complications and apposition with native bone correlated with non-union.

Mixed Reality Combined with Surgical Navigation in Resection of Micro- and Mini-Tumors of the Parotid Gland: A Pilot Study

OBJECTIVE

This study aimed to evaluate the feasibility and outcomes of mixed reality combined with surgical navigation (MRSN) in the resection of parotid micro- and mini-tumors.

METHODS

Eighteen patients who underwent parotid tumor resection between December 2020 and November 2022 were included. Six patients were enrolled in MRSN group, and the surgeons performed the surgery with the help of MRSN technology. The surgical procedures include virtual planning, data transfer between mixed reality and surgical navigation, tumor localization and resection assisted by surgical navigation under mixed reality environment. Twelve patients were enrolled in control group, and intraoperative tumor localization and resection were performed according to the experience of the surgeon. Total surgery time and intraoperative bleeding were recorded. Perioperative complications were recorded during follow-up.

RESULTS

The mean surgery time of MRSN group (76.7 ± 14.0 min) and control group (65.4 ± 21.3 min) showed no significant difference (p = 0.220), so did the intraoperative bleeding of MRSN group (16.0 ± 8.0 mL) and control group (16.7 ± 6.6 mL) (p = 0.825). None of the patient in MRSN group underwent any complication, although one patient in control group suffered temporary facial paralysis. The mean deviation between the virtually marked and the intraoperative actual outermost point of tumor was 3.03 ± 0.83 mm.

CONCLUSION

MRSN technology can realize real-time three-dimensional visualization of the tumor, and it has the potential of enhancing the safety and accuracy of resection of micro- and mini-tumors of parotid gland.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:1670-1678, 2024.

Cutting guides in mandibular tumor ablation: Are we as accurate as we think?

Purpose

Tumor margin status is critical in local tumor recurrence and is a significant prognostic factor in head and neck cancer survival. With the introduction of computer-assisted surgical planning, one of the main challenges is the accurate positioning of the surgical cutting guide but there is limited evidence of the accuracy of the 3D cutting guides in mimicking virtually planned osteotomy. This study evaluates the accuracy of osteotomy lines produced by 3D-printed cutting guides and assesses the overall accuracy of mandibular reconstruction.

Material and Methods

The pre and postoperative 3D models were aligned using an automated surface registration feature based on the iterative closest point algorithm. The differences in osteotomy line deviation, linear and angle measurements, and 3D volume quantification of the pre and post models were measured.

Results

We included 14 patients (8 men and 6 women with ages ranging from 13 to 75 years) with a segmental mandibular resection who met all of the inclusion criteria. The smallest defect size was 4.4 cm, the largest defect was 12.2 cm, and the average was 7.30 cm +/- 2.80 cm. The average deviation between virtually planned osteotomy and actual surgical osteotomy was 1.52 +/-1.02 mm. No covariates were associated with increased inaccuracy of the 3D-printed cutting guides.

Conclusion

The finding of this study suggests that virtual surgical planning is an unambiguous paradigm shift in the predictability of the surgical plan and achievement of the reconstruction goals. The 3D-printed cutting guides are a very accurate and reliable tool in translating virtual ablation plans to an actual surgical resection margin.

Biomechanical behavior of the three-dimensionally printed surgical plates for mandibular defect reconstruction: a finite element analysis

The aim of the study was to investigate the biomechanical behavior of three-dimensionally (3D)-printed surgical plates used for mandibular defect reconstruction, compare them with conventional surgical plates, and provide experimental evidence for their clinical application. Three-dimensional models were created for the normal mandible and for mandibular body defects reconstructed using free fibula and deep circumflex iliac artery flaps. Three-dimensional finite element models of reconstructed mandibles fixed using 3D-printed and conventional surgical plates were established. Vertical occlusal forces were applied to the remaining teeth and the displacement and Von Mises stress distributions were studied using finite element analysis. The normal and reconstructed mandibles had similar biomechanical behaviors. The displacement distributions for the surgical plates were similar, and the maximum total deformation occurred at the screw hole of the anterior segment of the surgical plates. However, there were differences in the Von Mises stress distributions for the surgical plates. In reconstructed mandibles fixed using 3D-printed surgical plates, the maximum equivalent Von Mises stress occurred at the screw hole of the posterior segment, while in those fixed using conventional surgical plates, the maximum equivalent Von Mises stress was at the screw hole of the anterior segment. In the mandible models reconstructed with the same free flap but fixed with different surgical plates, the plates had similar biomechanical behaviors. The biomechanical behavior of 3D-printed surgical plates was similar to conventional surgical plates, suggesting that 3D-printed surgical plates used to reconstruct mandibular body defects with vascularized autogenous bone grafts could lead to secure and stable fixation.

Automated detection of cephalometric landmarks using deep neural patchworks

OBJECTIVES

This study evaluated the accuracy of deep neural patchworks (DNPs), a deep learning-based segmentation framework, for automated identification of 60 cephalometric landmarks (bone-, soft tissue- and tooth-landmarks) on CT scans. The aim was to determine whether DNP could be used for routine three-dimensional cephalometric analysis in diagnostics and treatment planning in orthognathic surgery and orthodontics.

METHODS

Full skull CT scans of 30 adult patients (18 female, 12 male, mean age 35.6 years) were randomly divided into a training and test data set (each n = 15). Clinician A annotated 60 landmarks in all 30 CT scans. Clinician B annotated 60 landmarks in the test data set only. The DNP was trained using spherical segmentations of the adjacent tissue for each landmark. Automated landmark predictions in the separate test data set were created by calculating the center of mass of the predictions. The accuracy of the method was evaluated by comparing these annotations to the manual annotations.

RESULTS

The DNP was successfully trained to identify all 60 landmarks. The mean error of our method was 1.94 mm (SD 1.45 mm) compared to a mean error of 1.32 mm (SD 1.08 mm) for manual annotations. The minimum error was found for landmarks ANS 1.11 mm, SN 1.2 mm, and CP_R 1.25 mm.

CONCLUSION

The DNP-algorithm was able to accurately identify cephalometric landmarks with mean errors <2 mm. This method could improve the workflow of cephalometric analysis in orthodontics and orthognathic surgery. Low training requirements while still accomplishing high precision make this method particularly promising for clinical use.

Three-Dimensional Digitalized Virtual Planning of Free Anterior Tibial Artery Perforator Flap for Repairing Soft Tissue Defects in Extremities

BACKGROUND

Traditional research methods have limited the application of anterior tibial artery perforator flap due to incomplete knowledge of the perforator. This study aimed to investigate the feasibility of three-dimensional digitalized virtual planning of free anterior tibial artery perforator flap for repairing soft tissue defects in extremities.

METHODS

A total of 11 patients with soft tissue defects in extremities were included. The patient underwent computed tomography angiography (CTA) of bilateral lower limbs, and then the three-dimensional models of bones, arteries, and skin were constructed. Septocutaneous perforators with appropriate length and diameter were selected to design anterior tibial artery perforator flaps in software, and the virtual flaps were superimposed onto the patient's donor site in a translucent state. During the operation, the flaps were dissected and anastomosed to the proximal blood vessel of the defects as designed.

RESULTS

Three-dimensional modeling showed clear anatomical relationships between bones, arteries, and skin. The origin, course, location, diameter, and length of the perforator obtained during the operation were consistent with those observed preoperatively. Eleven anterior tibial artery perforator flaps were successfully dissected and transplanted. Postoperative venous crisis occurred in one flap, partial epidermis necrosis occurred in another flap, while the remaining flaps completely survived. One flap was treated with debulking operation. The remaining flaps maintained aesthetic appearance, which did not affect the function of the affected limbs.

CONCLUSIONS

Three-dimensional digitalized technology can provide comprehensive information on anterior tibial artery perforators, thus assisting in planning and dissecting patient-specific flaps for repairing soft tissue defects in extremities.

Comparative evaluation of a patient-specific customised plate designs and screws for partial mandibular reconstruction

Mandibles with odontogenic tumors are often partially reconstructed with a metallic bone graft analogue with dental roots, crowns, along with a customized plate fixed with monocortical or bicortical screws, following resection of the tumor. In this study, two different designs of patient specific customized Ti reconstruction plates, solid and plate with holes, were considered. Fixation through both bicortical and monocortical screw types were investigated. FE models of the reconstructed mandibles were developed to analyse the influence of the plate-screw type combination on the load transfer across the mandibles under a mastication cycle. The effective homogenized orthotropic material properties of the lattice structures with 0.6 mm fibre diameter with 0.5 mm inter-fibre space were assigned to material properties for the bone graft analogue. The study shows that the combination of plate and screw types influences the state of stresses in the reconstructed mandible. Based on the results of this patient specific study, following resection of the tumor, either solid Ti plate with bicortical screws or Ti plate with holes along with monocortical screws may be used for partial mandibulectomy. It should also be noted that stresses in none of the plates or screws exceeded the yield limit for Ti under the mastication cycle indicating that the components are safe for mandibular reconstruction. However, the choice of this combination of reconstruction plates and screws is dependant on the condition and severity of the tumor in the diseased mandible.

Application of Augmented Reality to Maxillary Resections: A Three-Dimensional Approach to Maxillofacial Oncologic Surgery

In the relevant global context, although virtual reality, augmented reality, and mixed reality have been emerging methodologies for several years, only now have technological and scientific advances made them suitable for revolutionizing clinical care and medical settings through the provision of advanced features and improved healthcare services. Over the past fifteen years, tools and applications using augmented reality (AR) have been designed and tested in the context of various surgical and medical disciplines, including maxillofacial surgery. The purpose of this paper is to show how a marker-less AR guidance system using the Microsoft^® HoloLens 2 can be applied in mandible and maxillary demolition surgery to guide maxillary osteotomies. We describe three mandibular and maxillary oncologic resections performed during 2021 using AR support. In these three patients, we applied a marker-less tracking method based on recognition of the patient's facial profile. The surgeon, using HoloLens 2 smart glasses, could see the virtual surgical planning superimposed on the patient's anatomy. We showed that performing osteotomies under AR guidance is feasible and viable, as demonstrated by comparison with osteotomies performed using CAD-CAM cutting guides. This technology has advantages and disadvantages. However, further research is needed to improve the stability and robustness of the marker-less tracking method applied to patient face recognition.

Patient-centred outcomes and dental implant placement in computer-aided free flap mandibular reconstruction: a systematic review and meta-analysis

Computerised surgical planning (CSP) and computer-aided design and manufacturing (CAD/CAM) have been demonstrated to increase surgical accuracy and reduce operative time in free flap mandibular reconstruction, but evidence is lacking as to their impact on patient-centred outcomes. Implant-supported dental prostheses, however, have been associated with improved quality of life outcomes following free flap mandibular reconstruction. We aim to review reported patient-centred outcomes in mandibular reconstruction with CSP and CAD/CAM and determine whether use of these technologies is associated with higher rates of dental implant placement following free flap mandibular reconstruction. On December 20, 2020, a systematic review and meta-analysis were conducted according to PRISMA guidelines for studies reporting quality of life, functional outcomes, and rates of dental implant placement in computer-aided free flap mandibular reconstruction. A random-effects meta-analysis was performed to compare dental implant placement rates between surgeries using CSP and those using conventional freehand techniques. A total of 767 articles were screened. Nine articles reporting patient-centred outcomes and 16 articles reporting dental implant outcomes were reviewed. Of those reporting dental implant outcomes, five articles, representing a total of 302 cases, were included in the meta-analysis. Use of CSP was associated with a significant increase in the likelihood of dental implant placement, with an odds ratio of 2.70 (95% CI 1.52 to 4.79, p = 0.0007). Standardised reporting methods and controlled studies are needed to further investigate the impact of CSP and CAD/CAM technologies on functional outcomes and patient-reported quality of life in free flap mandibular reconstruction. Use of CSP and CAD/CAM technologies is associated with higher rates of dental implant placement in patients undergoing free flap mandibular reconstruction when compared to conventional freehand techniques.

Surgical Navigation in Mandibular Reconstruction: Accuracy Evaluation of an Innovative Protocol

Aim: the purpose of this work is to present an innovative protocol for virtual planning and surgical navigation in post-oncological mandibular reconstruction through fibula free flap. In order to analyze its applicability, an evaluation of accuracy for the surgical protocol has been performed. Methods: 21 patients surgically treated for mandibular neoplasm have been included in the analysis. The Brainlab Vector Vision 3.0^® software for surgical navigation has been used for preoperative surgical planning and intra-operative navigation. A post-operative accuracy evaluation has been performed matching the position of mandibular landmarks between pre-operative and post-operative CT scans. Results: the maximal discrepancy observed was included between −3.4 mm and +3.2 mm, assuming negative values for under correction and positive values for overcorrection. An average grade of accuracy included between 0.06 ± 0.58 mm and 0.43 ± 0.68 mm has been observed for every mandibular landmark examined, except for mandibular angles that showed a mean discrepancy value included between 1.36 ± 1.73 mm and 1.46 ± 1.02 mm when compared to preoperative measurements. Conclusion: a satisfying level of accuracy has been observed in the protocol presented, which appears to be more versatile if compared to closed custom-made systems. The technique described may represent a valid option for selected patients, but it cannot be considered for routine activity because of the complexity of the method, the mobility of the jaw, the necessity of surgical navigator and the long surgical learning curve that is required.

Comparing the use of conventional and three-dimensional printing (3DP) in mandibular reconstruction

Background

There are a number of clinical disorders that require mandibular reconstruction (MR). Novel three-dimensional (3D) printing technology enables reconstructions to be more accurate and beneficial to the patient. However, there is currently no evidence identifying which techniques are better suited for MR, based on the type of clinical disorder the patient has. In this study, we aim to compare 3D techniques with conventional techniques to identify how best to reconstruct the mandible based on the clinical cause that necessitates the reconstructive procedure: cancerous or benign tumours, clinical disorders, infection or disease and trauma or injury.

Methods

PubMed, Scopus, Embase and Medline were searched to identify relevant papers that outline the clinical differences between 3D and conventional techniques in MR. Data were evaluated to provide a clear outline of suitable techniques for surgery.

Results

20 of 2749 papers met inclusion criteria. These papers were grouped based on the clinical causes that required MR into four categories: malignant or benign tumour resection; mandibular trauma/injury and other clinical disorders.

Conclusions

The majority of researchers favoured 3D techniques in MR. However, due to a lack of standardised reporting in these studies it was not possible to determine which specific techniques were better for which clinical presentations.

Accuracy of Mixed Reality Combined With Surgical Navigation Assisted Oral and Maxillofacial Tumor Resection

OBJECTIVE

To evaluate the feasibility and accuracy of mixed reality combined with surgical navigation in oral and maxillofacial tumor surgery.

METHODS

Retrospective analysis of data of seven patients with oral and maxillofacial tumors who underwent surgery between January 2019 and January 2021 using a combination of mixed reality and surgical navigation. Virtual surgical planning and navigation plan were based on preoperative CT datasets. Through IGT-Link port, mixed reality workstation was synchronized with surgical navigation, and surgical planning data were transferred to the mixed reality workstation. Osteotomy lines were marked with the aid of both surgical navigation and mixed reality images visualized through HoloLens. Frozen section examination was used to ensure negative surgical margins. Postoperative CT datasets were obtained 1 week after the surgery, and chromatographic analysis of virtual osteotomies and actual osteotomies was carried out. Patients received standard oncological postoperative follow-up.

RESULTS

Of the seven patients, four had maxillary tumors and three had mandibular tumors. There were total of 13 osteotomy planes. Mean deviation between the planned osteotomy plane and the actual osteotomy plane was 1.68 ± 0.92 mm; the maximum deviation was 3.46 mm. Chromatographic analysis showed error of ≤3 mm for 80.16% of the points. Mean deviations of maxillary and mandibular osteotomy lines were approximate (1.60 ± 0.93 mm vs. 1.86 ± 0.93 mm). While five patients had benign tumors, two had malignant tumors. Mean deviations of osteotomy lines was comparable between patients with benign and malignant tumors (1.48 ± 0.74 mm vs. 2.18 ± 0.77 mm). Intraoperative frozen pathology confirmed negative resection margins in all cases. No tumor recurrence or complications occurred during mean follow-up of 15.7 months (range, 6-26 months).

CONCLUSION

The combination of mixed reality technology and surgical navigation appears to be feasible, safe, and effective for tumor resection in the oral and maxillofacial region.

Navigation-assisted maxillofacial reconstruction: accuracy and predictability

The aim of this study was to evaluate the accuracy of navigation-assisted maxillofacial reconstruction and to identify the predictors of the clinical outcomes. A total of 112 patients who underwent navigation-assisted maxillofacial reconstruction with free flaps between 2014 and 2019, performed by a single surgical team, were assessed. Accuracy was evaluated by superimposing the postoperative computed tomography data with the preoperative virtual surgical plan. Predictors of the clinical outcomes affecting the accuracy were identified and analysed. The mean deviation and root mean square (RMS) estimate of the orbital, maxillary, and mandibular reconstructions were 0.88 ± 3.25 mm and 3.38 ± 0.73 mm, 0.77 ± 3.44 mm and 3.69 ± 0.82 mm, and 1.07 ± 4.16 mm and 4.67 ± 3.95 mm, respectively (P < 0.05). There was no significant difference in orbital volume or projection between the preoperative, postoperative, and healthy orbits (P = 0.093 and P = 0.225, respectively). Multivariate linear regression analysis confirmed significant associations between the accuracy of navigation-assisted mandibular reconstruction and preservation of the condyle, type of reconstruction, type of osteosynthesis plate, and number of bony segments. Navigation-assisted midface reconstruction yielded a higher level of accuracy in the final surgical outcome when compared to mandibular reconstruction. Computer-assisted techniques and intraoperative navigation can be an alternative or adjunct to current surgical techniques to improve the final surgical outcome, especially in more complex maxillofacial reconstructions.

Digitally reconstructed severe trauma-induced oro-maxillofacial defects with free vascularised composite tissue flaps

The aim of this study was to outline the characteristics of severe trauma-induced oro-maxillofacial defects and explore the application of microsurgical reconstruction of these defects by selecting appropriate free vascularised composite tissue flaps. A retrospective analysis was performed in 11 cases with severe trauma-induced oro-maxillofacial defects from 2005 to 2018, All cases were reconstructed with free vascularised composite flaps using a supermicro-surgical/micro-surgical and digital technology. This study consisted of 11 patients (8 men, 3 women) with a median age (range) of 28 (6-64) years. Patients with long-standing trauma experienced severe scars and displacements. The trauma-induced oro-maxillofacial defects ranged in size from 4.0 × 5.0 cm² to 7 × 15 cm². Six radial forearm flaps, three fibular osteocutaneous flaps, a lateral thoracic flap, and an anterolateral thigh flap were harvested individually. All patients were treated effectively and followed up for over two years, with a 100% survival rate of these free vascularised composite tissue flaps. No uncontrollable complications occurred, and all patients were satisfied with the postoperative shape and function. The trauma-induced oro-maxillofacial defects display unique features, and microsurgical techniques play an important role in the reconstruction of shapes and function. In addition, some patients may need multi-stage surgeries to attain aesthetic refinement.

Automatic virtual reconstruction of maxillofacial bone defects assisted by ICP (iterative closest point) algorithm and normal people database

OBJECTIVES

The aim of this study was to propose and validate an automatic approach based on iterative closest point algorithm for virtual complement and reconstruction for maxillofacial bone defects.

MATERIALS AND METHODS

A 3D craniomaxillofacial database of normal Chinese people including 500 skull models was established. Modified iterative closest point (ICP) algorithm was developed to complete bone defects automatically. The performances were evaluated by two approaches: (1) model experiment, virtual bony defects were created on 30 intact normal skull models not included in the database. For each defect model, the algorithm was applied to select the reference skull model from the database. 3-Dimensional and 2-dimensional comparison were conducted to evaluate the error between reference skull model with original intact model. Root mean square error (RMSE) and processing time were calculated. (2) Clinical application, the algorithm was utilized to assist reconstruction of 5 patients with maxillofacial bone defects. The symmetry of post-operative skull model was evaluated by comparing with its mirrored model.

RESULTS

The algorithm was tested on an CPU with 1.80 GHz and average processing time was 493.5 s. (1) Model experiment, the average root-mean-square deviation of defect area was less than 2 mm. (2) Clinical application, the RMSE of post-operative skull and its mirrored model was 1.72 mm.

CONCLUSION

It is feasible using iterative closest point algorithm based on normal people database to automatically predict the reference data of missing maxillofacial bone.

CLINICAL RELEVANCE

An automated approach based on ICP algorithm and normal people database for maxillofacial bone defect reconstruction has been proposed and validated.

[Anatomy of the deep circumflex iliac artery perforators and reconstruction of complex mandibular defects with chimeric deep circumflex iliac artery perforator flap]

OBJECTIVE

To investigate the anatomy of the perforator vessels of the deep circumflex iliac artery (DCIA) and the techniques for repairing mandibular complex defect using chimeric deep circumflex iliac artery perforator flap (DCIAPF).

OBJECTIVE

We analyzed the origin, distribution, number and courses of the perforator vessels of the DCIA, and measured the outside diameters of the vessels at the origin in 6 adult cadaveric specimens (12 sides) with latex perfusion. From July, 2018 to September, 2019, based on the results of anatomical study and imaging findings and using the digital surgical guide plate, we harvested DCIAPF from 4 patients for repairing mandibular body or angle defects and oral soft tissue defects.

OBJECTIVE

The perforating vessels of the DCIA included abdominal muscular branches, osteomusculocutaneous branches and terminal musculocutaneous branches. The abdominal muscle branches originated from the DCIA inguinal segment in 4 and from both the inguinal and iliac segments in 2 of the specimens. The osteomusculocutaneous branches all originated from the internal iliac crest in 75% and from both the inguinal and internal iliac crest segments in 25% of cases; the inguinal segment gave rise to only one perforating branch. The number of the musculocutaneous perforating branches was 1 (58.3%) or 2 (41.7%). In the 4 patients undergoing mandibular reconstruction, the DCIAPF survived in all cases with good recovery of the donor site wound. Satisfactory facial appearance with good oral morphology and occlusal relationship was achieved at 1 month postoperatively in all the patients. None of the patients experienced obvious functional abnormalities at the donor site, and imaging examination confirmed successful reconstruction of the oromandibular defects in all the cases.

OBJECTIVE

A good understanding of the anatomic characteristics of the perforator vessels of the DCIA combined with imaging examinations and digital surgery technology facilitates the harvest of DCIAPF for repairing mandibular body or angle defects complicated by oral soft tissue defects.

Surgical benefit of mandibular morphometric analysis: A new tool to standardize mandibular reconstruction

PURPOSE

The gold-standard for reconstruction of large mandibular defects is the use of free flaps of vascularized autologous bone with the fibula as the preferred donor site. The use of "custom cutting guides" for this indication is becoming increasingly prevalent. But cost of the procedure averages around 2,500 dollars per patient excluding treatment and entails selection criteria. We think it is possible to standardize mandibular reconstructions from an anatomical mean. The objective of this study was to perform a mandibular morphometric analysis in order to obtain a set of "mean" measurements, which can be used by all surgeons interested in mandibular reconstruction.

METHODS

We performed a morphometric analysis consisting of three-dimensional mandibular reconstructions of 30 men and 30 women. Several reference points were set and defined to evaluate specific lengths and angles of interest. We conducted an intra and inter-sexual descriptive analysis of measurements obtained.

RESULTS

We did not identify any major intra-sexual differences within each group. The gonial angle is more open in women and the measurements characterizing the basilar contour are more prominent in men. We did not identify any differences in alveolar region parameters.

CONCLUSION

The results of this study constitute a morphological tool for surgeons, from bone graft to free flap. These results also confirm us that the use of «custom cutting guides» for mandibular reconstruction may be excessive. It is pertinent to examine the value of "custom made" mandibular reconstructions since the differences observed are of the order of millimeters.

Three-dimensional virtual surgical planning in the oncologic treatment of the mandible

OBJECTIVES

In case of surgical removal of oral squamous cell carcinomas, a resection of mandibular bone is frequently part of the treatment. Nowadays, such resections frequently include the application of 3D virtual surgical planning (VSP) and guided surgery techniques. In this paper, current methods for 3D VSP leads for optimisation of the workflow, and patient-specific application of guides and implants are reviewed.

RECENT FINDINGS

Current methods for 3D VSP enable multi-modality fusion of images. This fusion of images is not restricted to a specific software package or workflow. New strategies for 3D VSP in Oral and Maxillofacial Surgery include finite element analysis, deep learning and advanced augmented reality techniques. These strategies aim to improve the treatment in terms of accuracy, predictability and safety.

CONCLUSIONS

Application of the discussed novel technologies and strategies will improve the accuracy and safety of mandibular resection and reconstruction planning. Accurate, easy-to-use, safe and efficient three-dimensional VSP can be applied for every patient with malignancies needing resection of the mandible.

Post-traumatic maxillofacial reconstruction with vascularized flaps and digital techniques: 10-year experience

The aim of this study was to present a treatment protocol for the individual repair of post-traumatic maxillofacial bone defects with vascularized flaps assisted by digital techniques. This study reviewed 20 patients with post-traumatic maxillofacial bone defects who underwent reconstruction with composite vascularized bone flaps assisted by digital techniques between April 2009 and July 2019. Preoperative computed tomography (CT) data were imported into ProPlan CMF software to complete virtual fracture reduction and reconstruction. Surgical navigation, three-dimensionally (3D) printed surgical plates, and prefabricated titanium mesh/plates were used to guide the actual surgery. All patients underwent open reduction and internal fixation and reconstruction surgery in one stage. CT data obtained at 1 week postoperative were imported into Geomagic Control software to evaluate the accuracy of the virtual surgical plan. The mean follow-up interval was 24 months (range 6-96 months). Donor and recipient site morbidity and second-stage procedures to rehabilitate the dentition and cosmetic organs were recorded. The flap success rate was 100%. Nine patients had deep circumflex iliac artery flaps and eleven patients had fibula flaps. The accuracy of computer-assisted surgery was 4.4±0.8mm. There were no postoperative complications. This study is novel in presenting a treatment protocol for individual computer-assisted reconstruction for post-traumatic maxillofacial bone defects with vascularized flaps.

Recent advance in patient-specific 3D printing templates in mandibular reconstruction

Patient-specific 3D printing template is used in mandibular defect reconstruction with multiple deficiencies. During the operation, the template can accurately transfer the preoperative design, assisting surgeons to complete the surgery with high efficiency and accuracy. The template design has been continuously improved to obtain good application for miscellaneous classification and description. This review attempted to preliminarily analyse and summarise recent advancements in personalized 3D printing templates in mandibular reconstruction from the aspects of functional classification, existing problems, improved strategies and post-surgery evaluation by reviewing studies and through our combined clinical work and experience on hundreds of reconstruction surgeries.

Intraoperative Image-Guided Navigation in Craniofacial Surgery: Review and Grading of the Current Literature

INTRODUCTION

Image-guided navigation has existed for nearly 3 decades, but its adoption to craniofacial surgery has been slow. A systematic review of the literature was performed to assess the current status of navigation in craniofacial surgery.

METHODS

A Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) systematic review of the Medline and Web of Science databases was performed using a series of search terms related to Image-Guided Navigation and Craniofacial Surgery. Titles were then filtered for relevance and abstracts were reviewed for content. Single case reports were excluded as were animal, cadaver, and virtual data. Studies were categorized based on the type of study performed and graded using the Jadad scale and the Newcastle-Ottawa scales, when appropriate.

RESULTS

A total of 2030 titles were returned by our search criteria. Of these, 518 abstracts were reviewed, 208 full papers were evaluated, and 104 manuscripts were ultimately included in the study. A single randomized controlled trial was identified (Jadad score 3), and 12 studies were identified as being case control or case cohort studies (Average Newcastle-Ottawa score 6.8) The most common application of intraoperative surgical navigation cited was orbital surgery (n = 36), followed by maxillary surgery (n = 19). Higher quality studies more commonly pertained to the orbit (6/13), and consistently show improved results.

CONCLUSION

Image guided surgical navigation improves outcomes in orbital reconstruction. Although image guided navigation has promise in many aspects of craniofacial surgery, current literature is lacking and future studies addressing this paucity of data are needed before universal adoption can be recommended.

Accuracy of computer-assisted surgery in mandibular reconstruction: A systematic review

Computer-assisted surgery (CAS) for mandibular reconstruction was developed to improve conventional treatment methods. In the past years, many different software programs have entered the market, offering numerous approaches for preoperative planning and postoperative evaluation of the CAS process of mandibular reconstruction. In this systematic review, we reviewed planning and evaluation methods in studies that quantitatively assessed accuracy of mandibular reconstruction performed with CAS. We included 42 studies describing 413 mandibular reconstructions planned and evaluated using CAS. The commonest software was Proplan/Surgicase CMF (55%). In most cases, the postoperative virtual 3-dimensional model was compared to the preoperative 3-dimensional model, revised to the virtual plan (64%). The commonest landmark for accuracy measurements was the condyle (54%). Accuracy deviations ranged between 0 mm and 12.5 mm and between 0.9° and 17.5°. Because of a lack of uniformity in planning (e.g., image acquisition, mandibular resection size) and evaluation methodologies, the ability to compare postoperative outcomes was limited; meta-analysis was not performed. A practical and simple guideline for standardizing planning and evaluation methods needs to be considered to allow valid comparisons of postoperative results and facilitate meta-analysis in the future.

Three-dimensional accuracy of mandibular reconstruction by patient-specific pre-bent reconstruction plates using an "in-house" 3D-printer

PURPOSE

The purpose of this study was to compare the three-dimensional accuracy of mandibular reconstruction following mandible continuity resection in patients treated with patient-specific, pre-bent reconstruction plates, using an 'in-house' 3D printer, with that in patients treated with conventional, intraoperatively bent plates.

PATIENTS AND METHODS

We retrospectively analyzed 42 alloplastic mandibular reconstructions following continuity resection. 21 patients received patient-specific, pre-bent reconstruction plates using an in-house 3D printer. The control group consisted of 21 patients provided with intraoperatively bent reconstruction plates. Distances between corresponding anatomical landmarks on the mandibular angle and condyle (A-A', BB', CC', BC'), as well as the intercondylar angle (ICA), were measured and compared on the pre- and postoperative CT scans.

RESULTS

Multivariate analysis of variance (MANOVA) showed significant multivariate main effect of group (F_{(5, 36)} = 5.58, p = 0.001; Wilks lambda 0.564; partial η² = 0.436), indicating more accurate postoperative results for the pre-bent group. Post-hoc comparison revealed significantly larger postoperative deviation in the distances between the mandibular angle and the intercondylar angle (ICA) for the intraoperatively bent group in comparison with the pre-bent group. However, there was no significant effect on the distance between the condyles.

CONCLUSIONS

Mandibular reconstructions employing patient-specific, pre-bent reconstruction plates made using an in-house 3D printer show significantly better three-dimensional accuracy compared with intraoperatively bent plates. The described method prevents rotational error of the mandibular angle and improves restoration of the physiological intercondylar angle in mandible reconstruction after continuity resection.