Comparison of condylar position after free fibular flap mandibular reconstruction using computer-assisted and traditional techniques.

OBJECTIVES: To compare the changes in condylar position after mandibular reconstruction with free fibular flap(FFF) and the differences between computer-assisted techniques and traditional methods on CT images. METHODS: Thirty-four patients who underwent mandibular reconstruction with free fibular flap were selected according to the inclusion and exclusion criteria. In the 3D group, virtual surgical planning (VSP) with osteotomy cutting plate and placement guiding plate were used, while the traditional group underwent freehand reconstruction. The CT data of 68 temporomandibular joints (TMJs) were recorded before and immediately after surgery. The condylar position was evaluated by measuring the anterior space (AS), posterior space (PS) and superior space (SS), and the ln (PS/AS) was calculated according to the method proposed by Pullinger and Hollender. RESULTS: In the patients included in the 3D group, the condyle on the ipsilateral side moved slightly backward; however, in the patients in the traditional group, the ipsilateral side moved considerably anteroinferior. No obvious changes on the contralateral side were noted. In the 3D group, 33% of ipsilateral condyles were in the posterior position postoperatively when compared with the preoperative position (13%). In the traditional group, the number of ipsilateral condyles in the anterior position increased from 4 to 10, accounting for 53% postoperatively. Contrary to the traditional group, the 3D group presented less condylar displacement on the ipsilateral side postoperatively. CONCLUSIONS: This study showed a decreased percentage of change in condylar position postoperatively when VSP was used. Virtual surgical planning improved the accuracy of FFF mandibular reconstruction and made the condylar position more stable.

Technical refinements of the scapular tip-free flap for mandibular reconstruction.

BACKGROUND: The use of scapular tip chimeric free flaps (STFFs) for reconstructing mandibular defects has recently become popular, but its utility relative to other bone-containing free flaps remains debatable. The aim of the report is to describe how technical modification of STFF impacted in its use for mandibular reconstruction also commenting results obtained in a unicentric series of patients. PATIENTS AND METHODS: Patients undergoing mandibular reconstruction using an STFF from January 1, 2014 to June 1, 2022 were retrospectively enrolled in this report. We collected data on chimeric flap type, bone management, vascular pedicles, and the final outcomes. In total, 31 patients (13 men and 18 women) with a mean age of 68 years were enrolled. According to the classification system of Urken, 15 patients had body defects, while 7 had ramus defects, another 7 had symphysis defects, and 2 had both ramus and bodily defects. STFF was always harvested working in two equips simultaneously, in supine position. Dissection included preparation of chimeric components of the flap as latissimus dorsi, serratus and scapular tip. After pedicle dissection scapular bone was cut basing on reconstructive needing with a rectangular (stick) shape including the border of the scapula. In cases of longer bone harvesting, circumflex pedicle was also included to perfuse the upper portion of the scapular border. In five cases, the STFF was harvested with only the scapular angle component, and was thus a composite osteomuscular flap; for the remaining 26 cases, a chimeric STFF was used. Circumflex pedicle was included for eight patients. Six of the seven patients with symphyseal defects underwent a single osteotomy. RESULTS: The average length of the harvested was 69.92 mm (maximum length = 104 mm). The average height of transplanted bone was 26.78 mm (maximum height = 44.2 mm). Mouth-opening was normal in 25 patients, limited in 6 patients, and severely impaired in no patients. The cosmetic results were rated as excellent by 20 patients, good by 8 patients, and poor by 3 patients. CONCLUSION: The STFF is an excellent option for mandibular reconstruction when other flaps are not available and for patients in poor general condition. Technical innovations here presented made possible to harvest long bone segments with accurate shape thanks to osteotomies if needed and with adequate soft tissues components of the chimeric flap, ensuring satisfactory functional and cosmetic results.

Functional and esthetic outcomes of virtual surgical planning versus the conventional technique in mandibular reconstruction with a free fibula flap: A retrospective study of 24 cases.

This study aimed to compare the functional and esthetic results in patients following mandibular reconstruction with a free fibula flap (FFF) by virtual surgical planning (VSP) versus the conventional technique. Patients who had undergone mandibular reconstruction with a FFF by VSP or the conventional technique were retrospectively assessed. The two groups were compared regarding functional and esthetic variables with appropriate scales preoperatively, intraoperatively, and postoperatively. Twenty-four patients were evaluated in two groups: conventional (n = 8) and VSP (n = 16). The mean amount of mandibular asymmetry was 2.62 mm (SD = 1.59) in the conventional group and 1.19 mm (SD = 1.32) in the VSP group. Of the patients who underwent conventional surgery, 12.5% had mandibular asymmetry of <2 mm and 87.5% had asymmetry of 2-5 mm. Of the VSP patients, 61.5% had mandibular asymmetry of <2 mm and 38.5% had mandibular asymmetry of 2-5 mm (p = 0.03). The mean difference in size of mandibular angle on the surgical and control sides was not significantly different between the two groups (p = 0.62). The difference in mean length of the mandibular body on the surgical side relative to the control side was not significant between the two groups (p = 0.75). Differences in functional variables between the two groups were not significant. Within the limitation of the study, it seems that the VSP technique resulted in better facial symmetry and superior esthetic outcomes compared with the conventional technique.

Streamlining complex mandibular fracture treatment: Integration of virtual surgical planning and short-segment drilling guides.

This study aimed to evaluate the feasibility and accuracy of a combined virtual surgical planning (VPS) and short-segment drilling guides (SSDGs) workflow for the treatment of complex mandibular fractures. Consecutive patients with complex mandibular fractures underwent treatment using the VPS and SSDGs workflow from August 2020 to April 2022. Various mandibular landmarks were compared between the preoperative virtual surgical plan and postoperative data, including condylar distance (CoD), mandibular angle width (GoL-GoR), GoMeGo angle (∠GoL-Me-GoR), the difference in mandibular angles between the left and right sides (Δ∠Co-Go-Me), and the difference in length between the left and right mandibular body (ΔGo-Me). Additionally, preoperative preparation time and surgical duration were retrospectively analyzed and compared to conventional surgery. All 14 consecutive patients with complex mandibular fractures achieved successful reduction using the VPS and SSDGs workflow. Three-dimensional comparison revealed a mean deviation distance of 0.91 ± 0.50 mm and a root-mean-square deviation of 1.75 ± 0.47 mm between the preoperative designed mandible model and the postoperative mandible model. The percentage of points with deviation distances less than 2 mm, 1 mm, and 0.5 mm between preoperative and postoperative models were 78.47 ± 8.87 %, 60.02 ± 14.28 %, and 38.64 ± 15.48 %, respectively. There were no significant differences observed in CoD, GoL-GoR, ∠GoL-Me-GoR, Δ∠Co-Go-Me, and ΔGo-Me between preoperative virtual surgical planning and postoperative measurements. Furthermore, no significant differences were found in the injury-to-surgery interval, admission-to-surgery interval, and surgical duration between the workflow and conventional surgery. The combined VPS and SSDGs workflow proved to be an accurate and feasible method for treating complex mandibular fractures. It offers advantages such as minimal preoperative preparation time and the ability to precise transfer screw positions of the pre-bent reconstruction plate during surgery. This approach is particularly suitable for managing complex mandibular fractures.

Impact of virtual surgical planning and three-dimensional modeling on time to surgery in mandibular reconstruction by free fibula flap.

PURPOSE: Mandible reconstruction using a free fibula flap (FFF) is preferably performed with virtual surgical planning (VSP) to potentially improve functional and aesthetic outcomes. However, VSP is time-consuming. This study aims to assess the impact of VSP on time to surgery (TS). MATERIALS AND METHODS: All patients who underwent FFF for oral cavity cancer between 2007 and 2020 were included. Time to surgery (from the date of the first consultation to the surgery date) was compared between patients without VSP and with VSP. In our department, VSP and 3D modeling were performed by an external engineering laboratory. RESULTS: One hundred sixty-five patients were included retrospectively. VSP was utilized for 90 patients (55%). The mean time to surgery was 31 ± 16 days for patients undergoing conventional surgery without VSP and 44 ± 19 days for patients with VSP (p < 0.001). No clinical or tumoral characteristic were associated with a TS extended, except for the utilization of VSP (p < 0.001). By constituting groups of 25 consecutive patients, there is no difference in TS between the groups. CONCLUSION: The use of VSP significantly increased the time to surgery in our study, unrelated to clinical differences or year of surgery. This delay may have an impact on oncologic outcomes, so it should be considered in the care organization for each patient. Implementing new procedures to reduce this difference is warranted.

The comparison between various methods of mandibular reconstruction based on finite element analysis.

The Mandible can be damaged by pathological factors, tumors, trauma, infection, and needs a surgical operation for reconstruction and restoring function. There are different methods for the reconstruction of mandible. Based on the surgical approach, primary reconstruction of mandible by reconstruction plate after resection is necessary for maintaining mandibular symmetric and esthetic of the lower third of the face. A finite element model of mandible and masticatory muscles was produced from a normal person (male with 35-year-old). The normal model was resected from the left sixth tooth to the second tooth. The pathological model was reconstructed in different conditions by macro plate. Different conditions were analyzed and compared based on bite force on right fifth tooth, stress developed on screws and macro plate. The finite element analysis results showed that maximum bite force and lower stress on screws were seen in the pathological model (condition 5) when one macro plate and six screws were inserted in the mid-body. The findings showed that the use of two macro plates causes lower stress on it than when we use one. Use of one macro plate and six screws is the best choice in mandibular immobilization which decrease the stress applied on bone and increase the bite force. Because of less stress developed on macro plates and screws, use of two macro plates or one macro plate in mid-body area are also preferred.

Early outcomes of osteofascial versus osteocutaneous fibula free flap mandibular reconstruction.

BACKGROUND: This study compares early outcomes of osteofascial fibula free flap (OF-FFF) with donor-site primary closure and osteocutaneous (OC) FFF with donor-site skin grafting in segmental mandibular reconstruction. METHODS: A retrospective chart review of FFF mandibular reconstruction patients (2006-2022) divided into OF-FFF and OC-FFF groups. Clinical data, operative parameters, and early postoperative outcomes (≤ 90 days) were analyzed. RESULTS: The study included 67 patients (39 OF-FFF, 28 OC-FFF). OF-FFF had significantly lower donor-site complications (12.8% vs. 53.6%, p < 0.001) and revision surgeries (7.7% vs. 35.7%, p = 0.004) compared to OC-FFF. Recipient-site (28.2% vs. 25%, p = 0.77) and flap (15.4% vs. 17.9%, p > 0.99) complications were comparable. CONCLUSIONS: OF-FFF mandibular reconstruction with donor-site primary closure is a safe and reliable technique associated with superior donor-site and comparable flap and recipient-site outcomes to OC-FFF, thus may be considered as a viable alternative to OC-FFF for selected patients.

Efficacy of personalized 3D-printed osteotomy guide in maximizing fibular utilization and minimizing graft length for reconstruction of large mandibular defect.

OBJECTIVE: The study addresses the long-standing challenge of insufficient length in vascularized fibular flaps when reconstructing large mandibular defects that require dual-barrel grafts. Employing personalized 3D-printed osteotomy guides, the study aims to optimize fibular utilization and minimize the required graft length. MATERIAL AND METHODS: Two reconstruction methods for distal bone defects were compared: a fold-down (FD) group that employed a specialized osteotomy guide for folding down a triangular bone segment, and a traditional double-barrel (DB) group. Metrics for comparison included defect and graft lengths, as well as the graft-to-defect length ratio. Postoperative quality of life was assessed using the University of Washington Quality of Life questionnaire (UW-QoL). RESULT: Both FD and DB groups achieved successful mandibular reconstruction. Despite larger defects in the FD group (117 ± 31.35 mm vs 84 ± 35.34 mm, p = 0.028), the used fibula length was not statistically longer in the FD group. The median ratio of graft-to-defect length was also lower in the FD group (1.327 vs 1.629, p = 0.024), suggesting that FD required only 82.47% of the graft length needed in the DB approach. Quality of life scores post-surgery were comparable between the groups. CONCLUSION: Personalized 3D-printed osteotomy guides enhance fibula graft efficacy for reconstructing larger mandibular defects, necessitating shorter graft lengths while preserving postoperative quality of life. CLINICAL RELEVANCE: This study confirms the utility of 3D printing technology as an effective and precise tool in orthopedic surgery, particularly for complex reconstructions like large mandibular defects. It suggests a viable alternative that could potentially revolutionize current practices in bone grafting.

Computer-aided designed 3D-printed polymeric scaffolds for personalized reconstruction of maxillary and mandibular defects: a proof-of-concept study.

PURPOSE: To investigate the potential reconstruction of complex maxillofacial defects using computer-aided design 3D-printed polymeric scaffolds by defining the production process, simulating the surgical procedure, and explore the feasibility and reproducibility of the whole algorithm. METHODS: This a preclinical study to investigate feasibility, reproducibility and efficacy of the reconstruction algorithm proposed. It encompassed 3 phases: (1) scaffold production (CAD and 3D-printing in polylactic acid); (2) surgical simulation on cadaver heads (navigation-guided osteotomies and scaffold fixation); (3) assessment of reconstruction (bone and occlusal morphological conformance, symmetry, and mechanical stress tests). RESULTS: Six cadaver heads were dissected. Six types of defects (3 mandibular and 3 maxillary) with different degree of complexity were tested. In all case the reconstruction algorithm could be successfully completed. Bone morphological conformance was optimal while the occlusal one was slightly higher. Mechanical stress tests were good (mean value, 318.6 and 286.4 N for maxillary and mandibular defects, respectively). CONCLUSIONS: Our reconstructive algorithm was feasible and reproducible in a preclinical setting. Functional and aesthetic outcomes were satisfactory independently of the complexity of the defect.

In-house virtual surgical planning and guided mandibular reconstruction is less precise, but more economical and time-efficient than commercial procedures.

BACKGROUND: To compare an in-house and a commercially available surgical planning solution for mandibular reconstruction in terms of postoperative reconstruction accuracy and economic benefit. METHODS: Twenty-nine consecutive patients with advanced oral squamous cell carcinoma (OSCC) requiring segmental mandibular reconstruction were enrolled. Fifteen patients underwent in-house surgical planning and 14 patients underwent a commercially available planning solution. A morphometric comparison of preoperative and postoperative computed tomography (CT) data sets and a cost-benefit comparison were performed. RESULTS: Volumes of planned and reconstructed bone segments differed significantly for both in-house planning (p = 0.0431) and commercial planning (p < 0.0001). Significant differences in osteotomy angles were demonstrated for in-house planning (p = 0.0391). Commercial planning was superior to in-house planning for total mandibular deviation (p = 0.0217), intersegmental space volumes (p = 0.0035), and lengths (p = 0.0007). No significant difference was found between the two planning solutions in terms of intersegmental ossification and the incidence of wound healing disorders. In-house planning took less time than commercial planning (p < 0.0001). Component manufacturing costs (p < 0.0001) and total cumulative costs (p < 0.0001) were significantly lower for in-house planning. CONCLUSIONS: In-house surgical planning is less accurate but has a cost advantage and could be performed in less time.

Miniplate Versus Reconstruction Bar Fixation for Oncologic Mandibular Reconstruction with Free Fibula Flaps.

BACKGROUND: Fibula free flaps (FFF) are the gold standard tissue for the reconstruction of segmental mandibular defects. A comparison of miniplate (MP) and reconstruction bar (RB)-based fixation of FFFs has been previously described in a systematic review; however, long-term, single-center studies comparing the two plating methods are lacking. The authors aim to examine the complication profile between MPs and RBs at a single tertiary cancer center. We hypothesized that increased components and a lack of rigid fixation inherent to MPs would lead to higher rates of hardware exposure/failure. METHODS: A retrospective review was performed from a prospectively maintained database at Memorial Sloan Kettering Cancer Center. All patients who underwent FFF-based reconstruction of mandibular defects between 2015 and 2021 were included. Data on patient demographics, medical risk factors, operative indications, and chemoradiation were collected. The primary outcomes of interest were perioperative flap-related complications, long-term union rates, osteoradionecrosis (ORN), return to the operating room (OR), and hardware exposure/failure. Recipient site complications were further stratified into two groups: early (<90 days) and late (>90 days). RESULTS: In total, 96 patients met the inclusion criteria (RB = 63, MP = 33). Patients in both groups were similar with respect to age, presence of comorbidities, smoking history, and operative characteristics. The mean follow-up period was 17.24 months. In total, 60.6 and 54.0% of patients in the MP and RB cohorts received adjuvant radiation, respectively. There were no differences in rates of hardware failure overall; however, in patients with an initial complication after 90 days, MPs had significantly higher rates of hardware exposure (3 vs. 0, p = 0.046). CONCLUSION: MPs were found to have a higher risk of exposed hardware in patients with a late initial recipient site complication. It is possible that improved fixation with highly adaptive RBs designed by computer-aided design/manufacturing technology explains these results. Future studies are needed to assess the effects of rigid mandibular fixation on patient-reported outcome measures in this unique population.

Long-Term Outcomes after Pediatric Mandibular Reconstruction Using Vascularized Free Fibula Flap.

BACKGROUND: The purpose of this study was to evaluate the long-term outcomes of mandibular reconstruction with vascularized free fibula flap in pediatric patients. METHODS: Consecutive cases of mandibular reconstruction with vascularized free fibula flaps in pediatric patients at Peking University School and Hospital of Stomatology between 1999 and 2019 were reviewed. Postoperative computed tomography (CT) data of all patients were collected at each postoperative follow-up point, and after the age of 18 years. The length and height of the grafted fibula and the length of the remaining mandible were evaluated by measuring the three-dimensional CT data using ProPlan CMF 3.0 software. Lower limb function was evaluated using the Enneking evaluation scale. Facial symmetry was self-evaluated and scored. Statistical analysis was performed on the data obtained. RESULTS: Fourteen patients were included in this study. All flaps were successful. The CT measurement results showed growth in the length of the grafted fibula that reconstructed the mandibular ramus and the residual mandible ( P < 0.05). The height of the grafted fibula remained stable ( P > 0.05). Eight patients were followed up until they were older than 18 years, and the CT measurement results after 18 years showed an essentially symmetric mandible profile ( P > 0.05). All patients were satisfied with their postoperative facial symmetry. Enneking evaluation scores showed good recovery of lower limb functions. CONCLUSIONS: The vascularized free fibula flap for mandibular reconstruction in pediatric patients is safe and reliable. It also provides good cosmetic and functional outcomes, as it demonstrated positive growth. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Development and validation of a novel craniofacial statistical shape model for the virtual reconstruction of bilateral maxillary defects.

Bilateral maxillary defects are a challenge for fibula free flap reconstruction (FFFR) surgery due to limitations in virtual surgical planning (VSP) workflows. While meshes of unilateral defects can be mirrored to virtually reconstruct missing anatomy, Brown class c and d defects lack a contralateral reference and associated anatomical landmarks. This often results in poor placement of osteotomized fibula segments. This study was performed to improve the VSP workflow for FFFR using statistical shape modeling (SSM) - a form of unsupervised machine learning - to virtually reconstruct premorbid anatomy in an automated, reproducible, and patient-specific manner. A training set of 112 computed tomography scans was sourced from an imaging database by stratified random sampling. The craniofacial skeletons were segmented, aligned, and processed via principal component analysis. Reconstruction performance was validated on a set of 45 unseen skulls containing various digitally generated defects (Brown class IIa-d). Validation metrics demonstrated promising accuracy: mean 95th percentile Hausdorff distance of 5.47 ± 2.39 mm, mean volumetric Dice coefficient of 48.8 ± 14.5%, compactness of 7.28 × 105 mm2, specificity of 1.18 mm, and generality of 8.12 × 10-6 mm. SSM-guided VSP will allow surgeons to create patient-centric treatment plans, increasing FFFR accuracy, reducing complications, and improving postoperative outcomes.

Geometric Cuts by an Autonomous Laser Osteotome Increase Stability in Mandibular Reconstruction With Free Fibula Grafts: A Cadaver Study.

BACKGROUND: Nonunion and plate exposure represent a major complication after mandibular reconstruction with free fibula flaps. These drawbacks may be resolved by geometric osteotomies increasing intersegmental bone contact area and stability. PURPOSE: The aim of this study was to compare intersegmental bone contact and stability of geometric osteotomies to straight osteotomies in mandibular reconstructions with free fibula grafts performed by robot-guided erbium-doped yttrium aluminum garnet laser osteotomy. STUDY DESIGN, SETTING, SAMPLE: This cadaveric in-vitro study was performed on fresh frozen human skull and fibula specimens. Computed tomography (CT) scans of all specimens were performed for virtual planning of mandibular resections and three-segment fibula reconstructions. The virtual planning was implemented in a Cold Ablation Robot-guided Laser Osteotome. PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE: For predictor variables, straight and geometric puzzle-shaped osteotomies were designed at resection of the mandible and corresponding fibula reconstruction. MAIN OUTCOME VARIABLES: The primary outcome variable was the stability of the reconstructed mandible investigated by shearing tests. Moreover, secondary outcome variables were the duration of the laser osteotomies, the contact surface area, and the accuracy of the reconstruction, both evaluated on postsurgical CT scans. COVARIATES: Covariables were not applicable. ANALYSES: Data were reported as mean values (± standard deviation) and were statistically analyzed using an independent-sample t-test at a significance level of α = 0.05. Root mean square deviation was tested for accuracy. RESULTS: Eight skulls and 16 fibula specimens were used for the study. One hundred twelve successful laser osteotomies (96 straight and 16 geometrical) could be performed. Geometric osteotomies increased stability (110.2 ± 36.2 N vs 37.9 ± 20.1 N, P < .001) compared to straight osteotomies. Geometric osteotomy of the fibula took longer than straight osteotomies (10.9 ± 5.1 min vs 5.9 ± 2.2 min, P = .028) but could provide larger contact surface (431.2 ± 148.5 mm2 vs 226.1 ± 50.8 mm2, P = .04). Heat map analysis revealed a mean deviation between preoperational planning and postreconstructive CT scan of -0.8 ± 2.4 mm and a root mean square deviation of 2.51 mm. CONCLUSION AND RELEVANCE: Mandibular resection and reconstruction by fibula grafts can be accurately performed by a Cold Ablation Robot-guided Laser Osteotome without need for cutting guides. Osteotomy planning with geometric cuts offers higher stability and an increased bone contact area, which may enhance healing of the reconstructed mandible.

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.

Robot-assisted augmented reality surgical navigation based on optical tracking for mandibular reconstruction surgery.

PURPOSE: This work proposes a robot-assisted augmented reality (AR) surgical navigation system for mandibular reconstruction. The system accurately superimposes the preoperative osteotomy plan of the mandible and fibula into a real scene. It assists the doctor in osteotomy quickly and safely under the guidance of the robotic arm. METHODS: The proposed system mainly consists of two modules: the AR guidance module of the mandible and fibula and the robot navigation module. In the AR guidance module, we propose an AR calibration method based on the spatial registration of the image tracking marker to superimpose the virtual models of the mandible and fibula into the real scene. In the robot navigation module, the posture of the robotic arm is first calibrated under the tracking of the optical tracking system. The robotic arm can then be positioned at the planned osteotomy after the registration of the computed tomography image and the patient position. The combined guidance of AR and robotic arm can enhance the safety and precision of the surgery. RESULTS: The effectiveness of the proposed system was quantitatively assessed on cadavers. In the AR guidance module, osteotomies of the mandible and fibula achieved mean errors of 1.61 ± 0.62 and 1.08 ± 0.28 mm, respectively. The mean reconstruction error of the mandible was 1.36 ± 0.22 mm. In the AR-robot guidance module, the mean osteotomy errors of the mandible and fibula were 1.47 ± 0.46 and 0.98 ± 0.24 mm, respectively. The mean reconstruction error of the mandible was 1.20 ± 0.36 mm. CONCLUSIONS: The cadaveric experiments of 12 fibulas and six mandibles demonstrate the proposed system's effectiveness and potential clinical value in reconstructing the mandibular defect with a free fibular flap.

How Is a Cutting Guide With Additional Anatomical References Better in Fibular-Free Flap Mandibular Reconstruction? A Technical Strategy.

BACKGROUND: Computer-assisted surgery is used to design and manufacture cutting guides in mandibular reconstructions with fibula-free flaps. To improve the outcomes of the procedure, the aim of this research was to investigate and compare the accuracy of mandibular reconstruction following the use of 2 versus 3 anatomical reference cutting guides. METHODS: Eighteen sets of prototype bone models retrieved from an ameloblastoma patient were used for mock operations. The mandibular segmental osteotomies and fibular reconstructions were performed using 2 and 3 anatomical reference cutting guides in vivo surgeries. After reconstruction, the accuracy of the placed reference points was measured by superimposition of computed tomography images. RESULTS: The error in cutting guides when using 2 or 3 anatomical references showed no significant difference. The fibular and condylar errors of the cutting guide between 2 and 3 anatomical references showed no significant difference in every plate type. The difference in screw hole position errors between 2 and 3 anatomical reference cutting guides was not statistically significant. CONCLUSIONS: Two anatomical reference cutting guides are sufficient and reasonable enough for mandible resection. However, there were some limitations and errors in our study.

Influence of microvascular mandibular bony reconstruction on the posterior airway space: A retrospective cohort study.

INTRODUCTION: The posterior airway space (PAS) is a common site of passive obstructions with high morbidity. Surgical changes to the craniomandibular system may affect the PAS. Data regarding the effects of mandibular reconstruction using vascularized bone flaps on PAS are insufficient. This retrospective cohort study aimed to investigate changes in PAS after mandibular reconstruction. MATERIALS AND METHODS: Pre- and post-reconstructive computed tomography scans of 40 patients undergoing segmental mandibulectomy and mandibular reconstruction with deep circumflex iliac artery or fibula flaps were analyzed. Absolute differences in PAS geometry and relative trends of PAS volume changes were compared within the study population and between subgroups formed according to the extent of resection, timing and type of reconstruction, and presence of pre-reconstructive radiotherapy. RESULTS: Irradiated patients were characterized by an increase in PAS volume after reconstruction. Absolute differences in total PAS volume after reconstruction were significantly different (p = 0.024) compared to non-irradiated patients. Reconstruction of central mandible segments resulted in decrease of the cross-sectional PAS areas. Absolute differences in middle cross-sectional PAS area after reconstruction were significantly different (p = 0.039) compared to non-central reconstructions. Patients who received radiotherapy were less likely to show a total PAS volume reduction after reconstruction (OR: 0.147; p = 0.007), with values adjusted for gender, age, body mass index, timing and type of reconstruction, and transplant length. CONCLUSIONS: Mandibular reconstruction causes changes in PAS geometry. Specifically, reconstructions of central mandibular segments can lead to a reduction in the cross-sectional areas of PAS, and mandibular reconstructions in irradiated sites may cause an increase in PAS volume.

Biomechanical evaluation of CAD/CAM magnesium miniplates as a fixation strategy for the treatment of segmental mandibular reconstruction with a fibula free flap.

Titanium patient-specific (CAD/CAM) plates are frequently used in mandibular reconstruction. However, titanium is a very stiff, non-degradable material which also induces artifacts in the imaging. Although magnesium has been proposed as a potential material alternative, the biomechanical conditions in the reconstructed mandible under magnesium CAD/CAM plate fixation are unknown. This study aimed to evaluate the primary fixation stability and potential of magnesium CAD/CAM miniplates. The biomechanical environment in a one segmental mandibular reconstruction with fibula free flap induced by a combination of a short posterior titanium CAD/CAM reconstruction plate and two anterior CAD/CAM miniplates of titanium and/or magnesium was evaluated, using computer modeling approaches. Output parameters were the strains in the healing regions and the stresses in the plates. Mechanical strains increased locally under magnesium fixation. Two plate-protective constellations for magnesium plates were identified: (1) pairing one magnesium miniplate with a parallel titanium miniplate and (2) pairing anterior magnesium miniplates with a posterior titanium reconstruction plate. Due to their degradability and reduced stiffness in comparison to titanium, magnesium plates could be beneficial for bone healing. Magnesium miniplates can be paired with titanium plates to ensure a non-occurrence of plate failure.