Surgical navigation-assisted mandibular reconstruction with fibula flaps

Robot-guided osteotomy in fibula free flap mandibular reconstruction: a preclinical study

Various methods currently exist to guide fibular osteotomy positioning in fibula free flap mandibular reconstruction, but patient-specific navigation methods and cutting guides require experience, and may be time-consuming and/or expensive. This study describes a robot-guided osteotomy technique for mandible reconstruction using a fibula free flap according to virtual preoperative planning. The method was assessed on five 3D-printed models and a cadaveric model. The precision of the robot-guided osteotomy was evaluated by measuring the deviations between the lengths and angles of the fragments obtained and those of the virtual planning. The average deviation of the anterior and posterior crest lengths was 0.42 ± 0.29 mm for the 3D-printed models and 1.00 ± 0.53 mm for the cadaveric model. The average angle deviation was 1.90 ± 1.22° and 1.94 ± 0.69° for the 3D-printed and cadaveric models, respectively. The results of this preclinical study revealed that fibular osteotomy positioning guidance using a robot-positioned cutting guide may be a precise, easy-to-use technique that could be tailored for fibula free flap mandibular reconstruction.

Application of a modified osteotomy and positioning integrative template system (MOPITS) based on a truncatable reconstruction model in the precise mandibular reconstruction with fibula free flap: a pilot clinical study

BACKGROUND

Mandibular defects can greatly affect patients' appearance and functionality. The preferred method to address this issue is reconstructive surgery using a fibular flap. The current personalized guide plate can improve the accuracy of osteotomy and reconstruction, but there are still some problems such as complex design process and time-consuming. Therefore, we modified the conventional template to serve the dual purpose of guiding the mandible and fibula osteotomy and facilitating the placement of the pre-bent titanium.

METHODS

The surgery was simulated preoperatively using Computer-Aided Design (CAD) technology. The template and truncatable reconstruction model were produced in the laboratory using 3D printing. After pre-bending the titanium plate according to the contour, the reconstruction model was truncated and the screw trajectory was transferred to form a modified osteotomy and positioning integrative template system (MOPITS). Next, the patient underwent a composite template-guided vascularized fibula flap reconstruction of the mandible. All cases were reviewed for the total operative time and accuracy of surgery.

RESULTS

The procedures involved 2-4 fibular segments in 15 patients, averaging 3 fibular segments per procedure. The osteotomy error is 1.01 ± 1.02 mm, while the reconstruction angular error is 1.85 ± 1.69°. The preoperative and postoperative data were compared, and both p > 0.05. During the same operation, implant placement was performed on four patients, with an average operative time of 487.25 ± 60.84 min. The remaining malignant tumor patients had an average operative time of 397.18 ± 73.09 min. The average postoperative hospital stay was 12.95 ± 3.29 days.

CONCLUSIONS

This study demonstrates the effectiveness of MOPITS in facilitating precise preoperative planning and intraoperative execution of fibula flap reconstruction. MOPITS represents a promising and reliable tool for reconstructive surgery, particularly for inexperienced surgeons navigating the challenges of mandible defect reconstruction.

Contactless surface registration of featureless anatomy using structured light camera: application to fibula navigation in mandible reconstruction

PURPOSE

Mandibular reconstruction using fibula free flap is a challenging surgical procedure. To assist osteotomies, computer-assisted surgery (CAS) can be used. Nevertheless, precise registration is required and often necessitates anchored markers that disturb the patient and clinical flow. This work proposes a new contactless surface-based method adapted to featureless anatomies such as fibula to achieve a fast, precise, and reproducible registration.

METHODS

Preoperatively, a CT-scan of the patient is realized and osteotomies are virtually planned. During surgery, a structured light camera digitizes the fibula. The obtained intraoperative point cloud is coarsely registered with the preoperative model using 3 points defined in the CT-scan and located on the patient's bone with a laser beam. Then, a fine registration is performed using an ICP algorithm. The registration accuracy was evaluated comparing the position of points engraved in a 3D-printed fibula with their position in the registered model and evaluating resulting osteotomies. Accuracy and execution time were compared to a conventional stylus-based registration method. The work was validated in vivo.

RESULTS

The experiment performed on a 3D-printed model showed that execution time is equivalent to surface-based registration using a stylus, with a better accuracy (mean TRE of 0.9 mm vs 1.3 mm using stylus) and guarantee good osteotomies. The preliminary in vivo study proved the feasibility of the method.

CONCLUSION

The proposed contactless surface-based registration method using structured light camera gave promising results in terms of accuracy and execution speed and should be useful to implement CAS for mandibular reconstruction.

Cutting-edge patient-specific surgical plates for computer-assisted mandibular reconstruction: The art of matching structures and holes in precise surgery

Objectives

Cutting-edge patient-specific surgical plates (PSSPs) are supposed to improve the efficiency, precision, and functional outcomes of mandibular reconstruction. This study characterized the premium role of PSSPs in precise surgery and explored their working principles in computer-assisted mandibular reconstruction (CAMR).

Methods

The PSSPs-enhanced surgical precision was investigated through the model surgery and representative cases. Spatial deviations of reconstruction were characterized by comparing the reconstructed mandible with the virtually designed mandible. Working principles of PSSPs were distinguished by a review of evolving surgical techniques in CAMR.

Results

In the model surgery, spatial deviations between the virtually planned mandible and the reconstructed mandible were 1.03 ± 0.43 mm in absolute distance deviation, 1.70 ± 1.26 mm in intercondylar length, and 1.86 ± 0.91 mm in intergonial length in the study group of PSSPs, significantly smaller than in the control group of conventional prebent surgical plates. Meanwhile, in the study group, distance deviations were 0.51 ± 0.19 mm in bone-plate distance and 0.56 ± 0.28 mm in drilled screw holes, indicating the art of matching structures and holes. The PSSPs-enhanced CAMR was further demonstrated in three representative cases of mandibular reconstruction. Finally, four primary techniques of CAMR were summarized based on a review of 8,672 articles. The premium role of PSSPs was distinguished by the benefits of matching structures and holes.

Conclusions

The PSSPs-enhanced surgical precision was verified through the model surgery and demonstrated in human surgery. Compared to other surgical techniques of CAMR, PSSPs contributed to the precise surgery by the art of matching structures and holes.

Vascularized Free Fibular Flap in Oral and Maxillofacial Reconstruction: A 20-year Experience at a Single Institution Using 2640 Flaps

BACKGROUND

This retrospective study reviewed all patients who underwent oral and maxillofacial reconstruction with fibular flaps in the last 2 decades at a single hospital.

MATERIALS AND METHODS

We reviewed all patients with fibular flaps from 1999 to 2018. The following data were collected: sex; age; reconstruction region; diagnosis; the number of days spent in the hospital after surgery; time spent using a tourniquet for harvesting a fibula flap; vessels at the recipient site; the prevalence of unplanned reoperations; the prevalence of flap failure; history of preoperative radiotherapy; virtual surgical planning; segments of the fibula.

RESULTS

In total, 2640 patients were included. The mean age was 45.5 years. The most prevalent region of reconstruction was the mandible (n=2347, 88.9%). The most common diagnosis was squamous cell carcinoma (n=1057, 40.0%). The mean number of days spent in the hospital after surgery decreased year-by-year from 18.3 days to 10.4 days. The first choice of recipient artery was the facial artery (n=1643, 62.2%) and that of the recipient vein was the external jugular vein (n=1196, 45.3%). The prevalence of surgical success was 97.6%. Prevalence of unplanned reoperations was 7.5%.

CONCLUSIONS

The fibular flap was a good choice for oral and maxillofacial bony reconstruction in most cases.

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.

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.

Virtual Surgical Planning of Deep Circumflex Iliac Artery Flap for Midface Reconstruction

Objective

Midface reconstruction is challenging for functional and esthetic reasons. The present study analyzed the effect of virtual surgical planning (VSP) of the deep circumflex iliac artery (DCIA) flap for midface reconstruction.

Patients and Methods

Thirty-four patients who underwent midface reconstruction with the DCIA flap were included in this retrospective study. Of the 34 patients, 16 underwent preoperative VSP, which used a three-dimensionally printed surgical guide, computer-assisted navigation system, and pre-bent titanium implants to transfer VSP into real-world surgery. The other 18 patients underwent traditional midface reconstruction. The following were compared between the two groups: bony contact rate in the buttress region (BCR), dental arch reconstruction rate (DAR), surgical approach, position of vascular anastomosis, and dental implantation rate. The independent-samples t-test and Fisher's exact test were used for analysis. P < 0.05 was considered statistically significant.

Results

In total, 12 males and 22 females were included in this study. All patients underwent midface reconstruction using the DCIA flap at the same institution. The median age of patients was 33 years (range: 16-68 years). The average BCR and DAR values in the VSP group were 59.4% ± 27.9% and 87.5% ± 18.9%, respectively, which were significantly higher compared with the non-VSP group (P = 0.049 and P = 0.004, respectively). The dental implantation rate in the VSP group (50.0%) was significantly higher compared with the non-VSP group (11.1%; P = 0.023). The intraoral approach for tumor ablation and vascular anastomosis was the most frequent choice in both groups. There was no significant difference between the two groups. All patients were satisfied with facial symmetry postoperatively.

Conclusions

VSP could effectively augment the effect of midface reconstruction with the DCIA flap. Stronger bone contact in the buttress region and higher DAR provide more opportunity for dental implantation, which might be the best solution to improve masticatory function in patients with midface defects.

Salvage mandibular reconstruction: multi-institutional analysis of 17 patients

Unsuccessful mandibular reconstruction occasionally occurs, leaving the patient with undesirable function and contours. In such cases, second- or third-time corrective operations are challenging. However, published studies on the complicated retreatment of such patients are scarce. A retrospective analysis covering the years 2015-2019 was conducted in three centers. All 17 patients included had undergone prior failed mandibular reconstructions in other institutions. Salvage secondary or tertiary reconstructive surgeries were attempted and the results are presented. Major factors for these failed reconstructions included exposed non-vascularized bone grafts (n = 7, 41.2%), flap loss (n = 4, 23.5%), exposed artificial joint (n = 3, 17.6%), skewed occlusion with deformity (n = 1, 5.9%), non-union (n = 1, 5.9%), and recurrence (n = 1, 5.9%). Fibula flaps were transferred in 15 patients, while iliac flaps were used in two patients for mandibular re-do reconstructions. Virtual surgical designs were conducted in nine (52.9%) patients, with navigation-guided approaches performed in three cases. Postoperative functions were relatively favorable in these complicated mandibular re-do reconstruction cases. Mandibular symmetry (mandibular length and height; P = 0.002) and condylar position (P < 0.001) were regained after these re-do attempts. Secondary or tertiary mandibular re-do reconstruction can still achieve good functional outcomes with appropriate preoperative selection and well-conceived designs, especially with the aid of virtual surgery and navigation.

Mandibular Reconstruction With the Iliac Flap Under the Guidance of A Series of Digital Surgical Guides

ABSTRACT

The authors aimed to evaluate the accuracy of mandibular reconstruction with the iliac flap under the guidance of a series of digital surgical guides. Seven patients were enrolled to evaluate the accuracy of reconstruction immediately after surgery. Patients underwent mandibular reconstruction with a vascularized iliac flap guided by a series of digital surgical guides at the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, from September 2017 to June 2018.All flaps survived. Chromatographic analysis showed that the area with a chromatographic difference of ≤1 mm between preoperative virtual surgical planning model and postoperative mandible accounted for 73.97% ± 3.89% of mandible surface, the area ≤2 mm accounted for 87.21% ± 2.65%, and the area ≤3 mm accounted for 94.09% ± 2.50%. In all of the 7 cases, the mean of maximum deviation was 6.25 ± 1.00 mm, and the mean of average deviation was 0.95 ± 0.13 mm. The authors conclude that mandibular reconstruction with the iliac flap under the guidance of a series of digital surgical guides is accurate and effective.

Formulating an Easy, Affordable, and Reproducible Method for Virtual Planning and 3D Reconstruction: A State Institution's Approach for Mandibular Reconstruction

INTRODUCTION

Free fibula flap is now regarded as the criterion standard for mandibular reconstruction after oncological resection. However, the results are often confounded due to inappropriate estimate of defect or inappropriate angulation of osteotomy. Three-dimensional (3D) printing and virtual planning can be an effective tool to help in planning osteotomies, therefore simplifying the process. Unfortunately, in developing countries, it is considered to be an expensive and a time-consuming affair, refraining the surgeons to use this technology. We have devised a cheap (less than $35), rapid, and reproducible method for this process that can be performed by residents with the help of the operating surgeon using a freely available software.

MATERIALS AND METHODS

The study was conducted over a span of 5 years from 2016 to 2020. Forty patients were randomly categorized into 2 groups of 20 each, one of which underwent conventional free fibula flap and the other group consisted of those for whom 3D printing and virtual planning were used. Aesthetic outcome was measured by preoperative and postoperative CT scans with 3D reconstruction. Furthermore, the reconstruction time and total operative time were also measured in both these groups.

RESULTS

Comparative study clearly demonstrated a significantly better aesthetic outcome in the 3D printing and virtual planning group. The use of this modality significantly reduced the reconstruction time, which was 83.9 minutes in the cases group and 124 minutes in the control group.

CONCLUSIONS

Three-dimensional printing and virtual planning help to improve the quality of mandibular reconstruction giving a better aesthetic outcome. Besides, it also reduces the operative time and gives us a chance to use prebent implants used for reconstruction. Our methodology is simple, quick, and cost-effective; therefore, we believe that this tool can be incorporated often in free fibula flaps for mandibular reconstruction in developing countries such as ours.

Electromagnetic surgical navigation in patients undergoing mandibular surgery

The purpose of this study was to evaluate the feasibility of electromagnetic (EM) navigation for guidance on osteotomies in patients undergoing oncologic mandibular surgery. Preoperatively, a 3D rendered model of the mandible was constructed from diagnostic computed tomography (CT) images. Cutting guides and patient specific reconstruction plates were designed and printed for intraoperative use. Intraoperative patient registration was performed using a cone beam CT scan (CBCT). The location of the mandible was tracked with an EM sensor fixated to the mandible. The real-time location of both the mandible and a pointer were displayed on the navigation system. Accuracy measurements were performed by pinpointing four anatomical landmarks and four landmarks on the cutting guide using the pointer on the patient and comparing these locations to the corresponding locations on the CBCT. Differences between actual and virtual locations were expressed as target registration error (TRE). The procedure was performed in eleven patients. TREs were 3.2 ± 1.1 mm and 2.6 ± 1.5 mm using anatomical landmarks and landmarks on the cutting guide, respectively. The navigation procedure added on average half an hour to the duration of the surgery. This is the first study that reports on the accuracy of EM navigation in patients undergoing mandibular surgery.

Feasibility of the application of mixed reality in mandible reconstruction with fibula flap: A cadaveric specimen study

BACKGROUND

In recent years, a new technology, mixed reality (MR), has emerged and surpassed the limitations of augmented reality (AR) with its inability to interact with hologram. This study aimed to investigate the feasibility of the application of MR in mandible reconstruction with fibula flap.

METHODS

Computed tomography (CT) examination was performed for one cadaveric mandible and ten fibula bones. Using professional software Proplan CMF 3.0 (Materialize, Leuven, Belgium), we created a defected mandibular model and simulated the reconstruction design with these 10 fibula bones. The surgical plans were transferred to the HoloLens. We used HoloLens to guide the osteotomy and shaping of the fibular bone. After fixing the fibular segments using the Ti template, all segments underwent a CT examination. Before and after objects were compared for measurements of the location of fibular osteotomies, angular deviation of fibular segments, and intergonial angle distances.

RESULTS

The mean location of the fibular osteotomies, angular deviation of the fibular segments, and intergonial angle distances were 2.11 ± 1.31 mm, 2.85°± 1.97°, and 7.24 ± 3.42 mm, respectively.

CONCLUSION

The experimental results revealed that slight deviations remained in the accuracy of fibular osteotomy. With the further development of technology, it has the potential to improve the efficiency and precision of the reconstructive surgery.

Facial Reconstruction: A Systematic Review of Current Image Acquisition and Processing Techniques

Introduction: Plastic and reconstructive surgery is based on a culmination of technological advances, diverse techniques, creative adaptations and strategic planning. 3D imaging is a modality that encompasses several of these criteria while encouraging the others. Imaging techniques used in facial imaging come in many different modalities and sub-modalities which is imperative for such a complex area of the body; there is a clear clinical need for hyper-specialized practice. However, with this complexity comes variability and thus there will always be an element of bias in the choices made for imaging techniques. Aims and Objectives: The aim of this review is to systematically analyse the imaging techniques used in facial reconstruction and produce a comprehensive summary and comparison of imaging techniques currently available, including both traditional and novel methods. Methods: The systematic search was performed on EMBASE, PubMed, Scopus, Web of Science and Cochrane reviews using keywords such as "image technique/acquisition/processing," "3-Dimensional," "Facial," and "Reconstruction." The PRISMA guidelines were used to carry out the systematic review. Studies were then subsequently collected and collated; followed by a screening and exclusion process with a final full-text review for further clarification in regard to the selection criteria. A risk of bias assessment was also carried out on each study systematically using the respective tool in relation to the study in question. Results: From the initial 6,147 studies, 75 were deemed to fulfill all selection criteria and selected for meta-analysis. The majority of papers involved the use of computer tomography, though the use of magnetic resonance and handheld scanners using sonography have become more common in the field. The studies ranged in patient population, clinical indication. Seminal papers were highlighted within the group of papers for further analysis. Conclusions: There are clearly many factors that affect the choice of image acquisition techniques and their potential at being ideal for a given role. Ultimately the surgical team's choice will guide much of the decision, but it is crucial to be aware of not just the diagnostic ability of such modalities, but their treatment possibilities as well.

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.

Virtual Planning and 3D printing modeling for mandibular reconstruction with fibula free flap

Background

This study was to evaluate the use of virtual planning and 3D printing modeling in mandibular reconstruction and compare the operation time and surgical outcome of this technique with conventional method.

Material and Methods

Between 2014 and 2017, 15 patients underwent vascularized fibula flap mandibular reconstruction using virtual planning and 3D printing modeling. Titanium plates were pre-bent using the models and cutting guides were used for osteotomies. 15 patients who underwent mandibular reconstruction using fibula flap without aid of virtual planning and 3D printing models were selected as control group. The operation time was recorded and compared in two groups. Accuracy of reconstruction was measured by superimposing the preoperative image onto the postoperative image of mandible. The selected bony landmark, distance and angle were measured.

Results

The mean total operation time and reconstruction time were 1.60±0.37 and 5.54±0.50 hours in computer-assisted group, respectively; These were 2.58±0.45 and 6.54±0.70 hours in conventional group, respectively. Both operation time and reconstruction time were shorter in computer-assisted group. The difference between the preoperative and postoperative intercondylar distances, intergonial angle distances, anteroposterior distances and gonial angles were 2.92±1.15 and 4.48±1.41mm, 2.93±1.19 and 4.79±1.48mm, 4.31±1.24 and 5.61±1.41mm, 3.85±1.68° and 5.88±2.12° in the computer-assisted and conventional group, respectively. The differences between the preoperative and postoperative mandible is smaller in the computer-assisted group.

Conclusions

Virtual planning and 3D printing modeling have the potential to increase mandibular reconstruction accuracy and reduce operation time. we believe that this technology for mandibular reconstruction in selected patients will become a used method and improve the quality of reconstruction.

Key words:Mandibular reconstruction, fibula flap, virtual planning, computer-assisted design, 3D printing.

Translating Computer-Aided Design and Surgical Planning Into Successful Mandibular Reconstruction Using a Vascularized Iliac-Crest Flap

PURPOSE

This study evaluated the computer-aided approach to the reconstruction of mandibular defects using a vascularized iliac-crest flap.

MATERIALS AND METHODS

From December 2015 to October 2016, 14 patients (8 men and 6 women) 18 to 64 years old (median age, 29 yr) were treated at the Peking University School and Stomatology Hospital (Beijing, China). Biopsy specimens from all patients were subjected to histologic examination before segmental mandibulectomy. Computer-based surgical techniques, including virtual surgical planning, computer-aided design and manufacturing, rapid prototyping, and intraoperative navigation, were used to restore the anatomic continuity and configuration of the mandible using a vascularized iliac-crest flap. Two transverse dimensions and 1 anteroposterior (A-P) dimension were evaluated based on the virtual plan and postoperative computed tomogram. Lines from condylar head to condylar head and from gonial angle to gonial angle were defined as the transverse dimensions. A perpendicular line drawn from the mandibular midline to the center point on the condylar head to condylar head measurement was defined as the A-P dimension. Complications were evaluated during follow-up.

RESULTS

The flap success rate was 92.9% (13 of 14), with 1 flap failure. After the operation, there were no other serious complications in 13 of the 14 patients, who exhibited a good mandibular configuration with good occlusion. Furthermore, the height of bone graft was sufficient for implants. Healing of the recipient and donor sites with no serious complication was uneventful. The average surgical errors in the A-P dimension and transverse dimensions were 1.8 ± 1.0 mm (range, 0.2 to 3.7 mm), 2.2 ± 1.1 mm (range, 0.9 to 5.0 mm), and 2.6 ± 1.6 mm (range, 0.3 to 7.2 mm), respectively.

CONCLUSIONS

The use of these digital techniques was found to be a viable option for reconstruction of mandibular defects, but the results should be interpreted cautiously because of the small number of patients and the relatively short follow-up.

Navigation Guidance During Free Flap Mandibular Reconstruction: A Cadaveric Trial

Importance

Segmental mandibulectomy for tumors that distort the buccal surface of the mandible present a reconstructive challenge.

Objective

To determine whether mandible alignment after navigation-guided mandible reconstruction is better than alignment after non-template-assisted freehand reconstruction and as good as template-assisted reconstruction in a cadaveric trial.

Design, Setting, and Participants

A cadaveric trial using 10 specimens was conducted at a tertiary academic center. Fiducials were created on the ramus to compare alignment with each intervention. Segmental mandibulectomy was performed on each cadaver. Each cadaver underwent navigation-guided reconstruction, template-assisted reconstruction using a manually shaped plate, and non-template-assisted freehand reconstruction with plate contouring performed after mandibulectomy. The study was conducted from October 1, 2015, to January 1, 2016; data analysis was performed from February 1, 2016, to March 1, 2016.

Interventions

Segmental mandibulectomy, navigation-guided reconstruction, template-assisted reconstruction using a manually shaped plate, and non-template-assisted freehand reconstruction.

Main Outcomes and Measures

Ramus fiducial coordinates were recorded at baseline and after each intervention. Mandible dimensions were measured using cephalometric landmarks. Postintervention and baseline differences in ramus and mandible position were calculated.

Results

Ramus alignment was not significantly different between navigation-guided and template-assisted reconstruction, differing by 0.54 mm (98.3% CI, -0.38 to 1.47 mm). Non-template-assisted freehand reconstruction was associated with a 3.14-mm difference in alignment compared with template-assisted reconstruction (98.3% CI, 1.09 to 5.19 mm). Navigation-guided alignment resulted in a 3.69-mm improvement in alignment compared with non-template-assisted freehand reconstruction (98.3% CI, 1.79 to 5.58 mm). There was some improvement in the gonion-gonion and lingula mandibulae-lingula mandibulae (Lm-Lm) alignment for navigation-assisted compared with non-template-assisted freehand reconstruction by 1.97 mm (98.3% CI, -0.65 to 4.58 mm) and 1.39 mm (98.3% CI, -0.17 to 2.95 mm), respectively. There was marginal evidence of better Lm-Lm alignment for navigation-guided than template-assisted reconstruction (0.44 mm; 98.3% CI, -0.06 to 0.95 mm).

Conclusions and Relevance

Mandible alignment following navigation-guided reconstruction is similar to template-assisted reconstruction. Navigation-guided alignment is likely better than non-template-assisted freehand reconstruction, and navigation guidance offers a reliable technique for real-time adjustment when reconstructing complex surgical defects, such as tumors effacing the buccal cortex of the mandible.