Scope and limitations of methods of mandibular reconstruction: a long-term follow-up

Supraorbital Rim and Roof Reconstruction with Vascularized Fascia Lata and Autogenous Rib Graft

OBJECTIVE

Describe a novel technique for reconstruction of complex defects involving supraorbital rim and orbital roof.

METHODS

Retrospective chart review and description of surgical technique.

RESULTS

Four patients underwent tumor resection with neurosurgery (2 intraosseous hemangioma, 1 meningioma, and 1 ossifying fibroma), with mean tumor size of 42.6 cubic centimeters on preoperative imaging. All defects involved supraorbital rim and orbital roof. Patients were reconstructed with autogenous osseous rib graft for structure and contour and anterolateral thigh fascia lata (ALTFL) free flap to provide robust vascularity to rib bone and as a barrier between skull base dura and the orbit and/or sinonasal cavities. Two patients underwent resection and reconstruction using minimal access incisions, and two underwent major cranial and skull base resections. All flaps are vascularized via superficial temporal vessels. On postoperative follow-up (mean 33.5 months, range 8-48), all patients report no vision change or diplopia, with excellent contour symmetry to contralateral orbit. Follow-up imaging (mean 29.5 months, range 3-48) demonstrated maintained orbital volume and retention of rib bone graft compared to immediate postoperative imaging. There were no complications related to graft use. Minor complications include 1 patient with cerebrospinal fluid leak managed with lumbar drain placement and 1 patient with mild enophthalmos at 7-month follow-up.

CONCLUSION

We describe a series of patients who underwent a novel technique for reconstruction of complex defects involving supraorbital rim and orbital roof with autogenous osseous rib and vascularized ALTFL-free flap with excellent functional and cosmetic outcomes. This can be accomplished using minimal access techniques to minimize patient morbidity.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:654-658, 2024.

From bench to bedside - current clinical and translational challenges in fibula free flap reconstruction

Fibula free flaps (FFF) represent a working horse for different reconstructive scenarios in facial surgery. While FFF were initially established for mandible reconstruction, advancements in planning for microsurgical techniques have paved the way toward a broader spectrum of indications, including maxillary defects. Essential factors to improve patient outcomes following FFF include minimal donor site morbidity, adequate bone length, and dual blood supply. Yet, persisting clinical and translational challenges hamper the effectiveness of FFF. In the preoperative phase, virtual surgical planning and artificial intelligence tools carry untapped potential, while the intraoperative role of individualized surgical templates and bioprinted prostheses remains to be summarized. Further, the integration of novel flap monitoring technologies into postoperative patient management has been subject to translational and clinical research efforts. Overall, there is a paucity of studies condensing the body of knowledge on emerging technologies and techniques in FFF surgery. Herein, we aim to review current challenges and solution possibilities in FFF. This line of research may serve as a pocket guide on cutting-edge developments and facilitate future targeted research in FFF.

Bone reconstruction of extensive maxillomandibular defects in adults

Reconstruction of significant maxillomandibular defects is a challenge that has been much discussed over the last few decades. Fundamental principles were developed decades ago (bone bed viability, graft immobilization). Clinical decision-making criteria are highly relevant, including local/systemic factors and incision designs, the choice of material, grafting technique, and donor site morbidity. Stabilizing particulated grafts for defined defects-that is, via meshes or shells-might allow significant horizontal and vertical augmentation; the alternatives are onlay and inlay techniques. More significant defects might require extra orally harvested autologous bone blocks. The anterior iliac crest is often used for nonvascularized augmentation, whereas more extensive defects often require microvascular reconstruction. In those cases, the free fibula flap has become the standard of care. The development of alternatives is still ongoing (i.e., alloplastic reconstruction, zygomatic implants, obturators, distraction osteogenesis). Especially for these complex procedures, three-dimensional planning tools enable facilitated planning and a surgical workflow.

Alloplastic reconstruction of the mandible after subtotal mandibulectomy for medication-related osteonecrosis of the jaw: An update of the method

BACKGROUND

Reconstruction of continuity defects following osteonecrosis in multimorbid patients is challenging. In all cases of the predescribed palliative treatment method for alloplastic mandible reconstruction, plate fractures were detected in follow-up. We hypothesized that a modification could avoid these fractures, leading to stable long-term results.

METHODS

This retrospective study compares the original method with a modification using single, laser-sintered CAD-CAM plates instead of manually bent miniplates. The predescribed shuttering technique was used to reconstruct the mandible in its original shape with bone cement.

RESULTS

Uneventful wound healing was observed in 86% of the cases after modification of the method. No implant or plate fracture occurred.

CONCLUSIONS

The presented method should be considered as a treatment option for mandible reconstruction in elderly, multimorbid patients in palliative situations. The results of this study suggest that the modification of the method leads to significantly improved long-term stability. Donor site morbidity is avoided with this method of palliative surgery.

A novel alloplastic grid reconstruction plate for the mandible - Retrospective comparative clinical analysis of failure rates and specific complications

PURPOSE

This study aimed to investigate the effect of three different osteosynthesis plate systems on failure rates and complications after continuity-interrupting mandibular resections with alloplastic reconstructions.

MATERIALS AND METHODS

Records of respective patients from 2010 to 2020 were analyzed retrospectively. The analyses included the osteosynthesis plate type (2.4 MANDIBULAR (RP1: MANDIBULAR [Medicon®, Tuttlingen, Germany]; RP2: Modus® Reco 2.5 [Medartis®, Basel, Switzerland]; and RP3: Modus 2 Mandible [Medartis®, Basel, Switzerland]), extent & location of the defect, age, sex, radiotherapy, and nicotine abuse. In case of failure, timepoint, and the problem, namely oral/extraoral dehiscence, screw loosening, and plate fractures that led to removal, were analyzed. Complications were classified according to Clavien-Dindo system.

RESULTS

A total of 136 patients were included. The mean follow-up time was 18 ± 26 months. Survival rates after 1, 2, and 5 years were 69.9%, 66.9%, and 64.7%, respectively. Although survival was not significantly associated with the reconstruction system, the most frequent complications were seen in cases of RP1 & RP2 when compared to RP3 (p = 0.033). In brief, dehiscences were seen significantly less often in cases of RP3 (12.5%) when compared to RP1 (44.7%) and RP2 (26.9%; p = 0.024). Fractures of the osteosynthesis systems occurred in 3 of 4 cases (75%) with RP1, in 1 of 4 cases (25%) using RP2, and in no single case using the RP3 system (p = 0.03). Most of the observed complications occurred up to 12 months postoperatively. A total plate survival rate of 64.7% and a total plate complication rate of 47.8% were seen.

CONCLUSION

In conclusion, it seems that RP3 should be preferred over RP1 and RP2 regarding failure rates and complications.

Application of anatomy unit resection surgery for lateral basicranial surgical approach in oral squamous carcinoma

BACKGROUND

The basicranial region lacks definite boundaries and includes various anatomical units. We developed a novel concept of the posterior oral anatomical complex (POAC) to identify these anatomical units in the basicranial region. OSCC with POAC involvement is termed posterior oral squamous cell carcinoma (POSCC) with poor prognosis. The principal aim of this study was to evaluate the effect of anatomy unit resection surgery (AUSR) on patients with POSCC.

METHODS

A total of 120 POSCC patients who underwent radical surgical treatment were recruited for this study. These POSCC patients were treated with conventional surgery or AUSR. According to the extent of primary tumor resection in the AUSR group, the lateral basicranial surgical approach can be subdivided into four types: face-lateral approach I, face-lateral approach II, face-median approach or face-median and face-lateral combined approach. Facial nerve function was evaluated according to the House-Brackmann Facial Nerve Grading System.

RESULTS

The overall survival rate was 62.5% and 37.5% in the AURS group and conventional group (hazard ratio: 0.59; p < 0.0001), respectively. The disease-free survival rate was 62.5% and 34.3% in the AURS group and conventional group (hazard ratio: 0.43; p = 0.0008), respectively. The local disease control rate in the AURS group (71.4%) was significantly better than that in the conventional group (34.4%) in present study (p < 0.0001). Compared to the conventional group, all the patients undergoing AURS were classified as T4 stage and presented with more lymph node metastasis (71.4%). A total of 20 patients (face-lateral approach I and face-lateral combined approach) were temporarily disconnected from the temporofacial branch of the facial nerve. Fifteen patients exhibited slight paresis, and five patients presented with moderate or severe paresis. The survival rate of zygomatic arch disconnection was 94.6% (54 of 56 patients).

CONCLUSION

This lateral basicranial surgical approach based on AUSR improves the survival rate and enhances the local control rate while also preserving a good prognosis without damaging the nerve and zygomatic bone. This surgical approach based on AUSR provides a novel and effective surgical treatment to address POSCC with better prognosis, especially for patients without metastatic lymph nodes.

Osseous Union after Jaw Reconstruction with Fibula-Free Flap: Conventional vs. CAD/CAM Patient-Specific Implants

This is a monocentric, retrospective study of patients who underwent successful immediate or delayed maxilla or mandible reconstructions with FFF from January 2005 to December 2021. Panoramic radiograph, computed tomography scans, and cone-beam CTs were analyzed concerning the osseous union of the intersegmental junctions between maxillary or mandibular native jaw and fibular bone. The primary parameter was to estimate the status of osseous union according to osteosynthesis type. A total number of 133 patients (PSI: n = 64, non-PSI: n = 69) were included in the present study. The mean age was 56.7 ± 14.0 (Range: 14.7−82.7); the primary diagnosis was in 105 patients a malignant (78.9%) and in 20 patients a benign (15.0%) tumor. Mandible reconstruction was performed on 103 patients (77.4%), and on 30 patients (22.6%), maxilla reconstruction was performed. The radiographic images provided a rate of incomplete osseous union (IOU) of about 90% in both groups in the first 6 months. Imaging between 6 and 12 months reveals an IOU rate in the non-PSI group of 46.3% vs. 52.5% in the PSI group, between 12 and 24 months, an IOU rate of 19.6% vs. 26.1%, between 24 and 36 months 8.9% vs. 21.7%, and after 36 months the IOU rate decreases to 4.2% vs. 18.2%. Multivariate logistic regression shows that only osteosynthesis type (OR = 3.518 [95%-CI = 1.223−10.124], p = 0.02) and adjuvant radiotherapy (OR = 4.804 [95%-CI = 1.602−14.409], p = 0.005) are independent risk factors for incomplete osseous union. Cox regression revealed that the variables plate-system (Hazard ratio, HR = 5.014; 95 %-CI: 1.826−3.769; p = 0.002) and adjuvant radiotherapy (HR = 5.710; 95 %-CI: 2.066−15.787; p < 0.001) are predictors for incomplete osseous union. In our study, the rate of incomplete bony fusion was significantly higher in the PSI group. Jaw-to-fibula apposition zones were significantly more affected than intersegmental zones. In multivariate analysis, a combination of osteosynthesis with PSI and adjuvant radiotherapy could be identified as a risk constellation for incomplete ossification.

A review on the classification of mandibulectomy defects and suggested criteria for a universal description

STATEMENT OF PROBLEM

Several mandibular defect classifications after oncological resection have been proposed with no universal acceptance among surgeons and prosthodontists. Established criteria for describing these mandibulectomy defects are lacking.

PURPOSE

The purpose of this systematic review was to analyze the classification systems of mandibular defects available in the scientific literature, provide a critical appraisal, and identify the criteria necessary for a universal description of mandibular discontinuity defects.

MATERIAL AND METHODS

An electronic search of the English language literature between 1971 and 2020 was performed on 2 electronic databases (PubMed and Cochrane Library). The search was conducted using MeSH terms and free text words: Mandible neoplasm AND Mandibular reconstruction OR Mandible resection OR Mandible defect AND classification, followed by the application of inclusion and exclusion criteria. Studies describing the classification of osteoradionecrosis of the mandible, mandibular fracture, impacted mandibular third molar, and mandibular endodontic or periodontal treatment were not included. The full texts of selected articles were reviewed in depth to provide a critical appraisal. The various descriptive factors of each classification system were tabulated to identify criteria suitable for the universal description of mandibular discontinuity defects.

RESULTS

The electronic search yielded a total of 239 titles and abstracts. Of these, 52 titles relevant to the review were identified by the 2 reviewers independently. Those studies that did not match the predetermined inclusion criteria and duplicates were excluded. By reviewing the 21 selected studies and applying exclusion criteria, 12 studies were selected for full-text reading. A manual search in the references of the selected publications was performed, which yielded 1 additional article that satisfied the inclusion criteria. Thus, a total of 13 full-text articles were included in the final review. After further qualitative analysis and tabulation of relevant information from selected classification systems, the 8 descriptive criteria and a pyramidal hierarchical chart were proposed that included the extent of bony defect, soft tissue defect, dental status, mandibular function, neurological status, condyle status, type of reconstruction, and combined resection.

CONCLUSIONS

The spectrum of patients with mandibulectomy defects following resection varies greatly. The question of the most ideal classification system remains unresolved. Eight different criteria for the description of mandibular discontinuity defects and the pyramidal hierarchical chart proposed will allow surgeons and prosthodontists to better communicate and conceptualize an individualized surgical and prosthetic treatment plan.

The Use of Customized Three-Dimensionally Printed Mandible Prostheses with a Pressure-Reducing Device: A Finite Element Analysis in Different Chewing Positions, Biomechanical Testing, and In Vivo Animal Study Using Lanyu Pigs

Segmental bony defects of the mandible constitute a complete loss of the regional part of the mandible. Although several types of customized three-dimension-printed mandible prostheses (CMPs) have been developed, this technique has yet to be widely used. We used CMP with a pressure-reducing device (PRD) to investigate its clinical applicability. First, we used the finite element analysis (FEA). We designed four models of CMP (P1 to P4), and the result showed that CMP with posterior PRD deployment (P4 group) had the maximum total deformation in the protrusion and right excursion positions, and in clenching and left excursion positions, posterior screws had the minimum von Mises stress. Second, the P4 CMP-PRD was produced using LaserCUSING from titanium alloy (Ti-6Al-4V). The fracture test result revealed that the maximum static pressure that could be withstood was 189 N, and a fatigue test was conducted for 5,000,000 cycles. Third, animal study was conducted on five male 4-month-old Lanyu pigs. Four animals completed the experiment. Two animals had CMP exposure in the oral cavity, but there was no significant inflammation, and one animal had a rear wing fracture. According to a CT scan, the lingual cortex of the mandible crawled along the CMP surface, and a bony front-to-back connection was noted in one animal. A histological examination indicated that CMP was significantly less reactive than control materials (p = 0.0170). Adequate PRD deployment in CMP may solve a challenge associated with CMP, thus promoting its use in clinical practice.

Utilization of non-vascularized bone graft with regional flap as an alternative for facial reconstruction

Mandibular resections decision is one of the most important steps in oral cavity malignant or nonmalignant lesions associated with the mandible. The role of mandibular reconstruction is not only for cosmesis, but it is also indicated for functional rehabilitation such as swallowing, phonetics, and for facial symmetrical. Even though the free tissue transfer is considered a gold standard for mandibular reconstruction, the importance of nonvascularized bone grafts (NVBGs) such as fibula, calvarium, rib, sternum, and iliac are still persisting in mandibulectomies condition like patient who have not taken radiotherapy or not willing to undergo radiotherapy or not fit for free tissue transfer and provides a good contour of mandibular replacement. The success rate of NVBG depends upon patient selection, preoperative planning, and meticulous nursing care. Addition to NVBG, regional flaps such as pectoralis major myocutaneous (PMMC) flap will help in soft-tissue replacement of the defect as well as it will help in the situation where primary closure and airtight closure is not possible. This case report will discuss in detail about the management of anterior segmental mandibulectomy due to oncological resection and reconstruction with NVBG with fibula and PMMC.

Biomechanical Evaluation and Factorial Analysis of the 3-Dimensional Printing Self-Designed Metallic Reconstruction Plate for Mandibular Segmental Defect

PURPOSE

Reconstruction plates are frequently used to treat mandibular segmental defects. The aim of this study is to compare the biomechanical performance of a 3-dimensional-printed self-designed titanium alloy reconstruction plate with that of the traditional reconstruction plate in mandible reconstruction. The analyzed parameters of the self-designed reconstruction plate, including plate length (100 mm and 125 mm), plate thickness (2.1, 2.4, and 2.7 mm), and bone mass (100, 75, and 50%), were also evaluated.

METHODS

An artificial mandible with anatomical geometry was used to develop the self-designed reconstructed plate. Both in vitro experiments and finite element simulations were performed for the biomechanical comparison of the self-designed and traditional reconstruction plates. In finite element analysis, 3 major muscle forces of mandible movement were set as the loading condition, and the displacement of the condyle was fixed in all directions as the boundary condition.

RESULTS

The biomechanical performances (stresses in the plate and strains in bone) of the self-designed reconstruction plate were superior to those of the traditional plate. Factorial analysis indicated that plate length and thickness had significant effects on decreasing stresses of the plate and mandibular bone.

CONCLUSIONS

The self-designed reconstruction plate might have a benefit to reduce the stresses/strains in plate itself and surrounding bone.

Procedure Increasing the Accuracy of Modelling and the Manufacturing of Surgical Templates with the Use of 3D Printing Techniques, Applied in Planning the Procedures of Reconstruction of the Mandible

The application of anatomical models and surgical templates in maxillofacial surgery allows, among other benefits, the increase of precision and the shortening of the operation time. Insufficiently precise anastomosis of the broken parts of the mandible may adversely affect the functioning of this organ. Applying the modern mechanical engineering methods, including computer-aided design methods (CAD), reverse engineering (RE), and rapid prototyping (RP), a procedure used to shorten the data processing time and increase the accuracy of modelling anatomical structures and the surgical templates with the use of 3D printing techniques was developed. The basis for developing and testing this procedure was the medical imaging data DICOM of patients treated at the Maxillofacial Surgery Clinic of the Fryderyk Chopin Provincial Clinical Hospital in Rzeszów. The patients were operated on because of malignant tumours of the floor of the oral cavity and the necrosis of the mandibular corpus, requiring an extensive resection of the soft tissues and resection of the mandible. Familiarity with and the implementation of the developed procedure allowed doctors to plan the operation precisely and prepare the surgical templates and tools in terms of the expected accuracy of the procedures. The models obtained based on this procedure shortened the operation time and increased the accuracy of performance, which accelerated the patient’s rehabilitation in the further course of events.

Use of anterior ramus bone graft for mandibular reconstruction in elderly patients

In this study, we investigated the feasibility of using a geometrically designed anterior ramus graft to reconstruct lateral mandibular defects. This was achieved by assessing the anatomical dimensions of the mandibular ramus on computed-tomographies. The design sequence and application of the graft was also demonstrated using one of our cases. The following dimensions were measured; a and b - horizontal length from mid-ramus to the posterior and anterior ramus border respectively, c - longest length of the graft, Mp - width at the centre of the ramus, h - vertical length of the angle at its cross-section, w - horizontal length of the angle at its cross-section, x - cross-sectional area along the mandible angle. A total of 80 mandibular rami were examined. The mean length of a, b, c were 17.3 ± 1.8 mm, 15.9 ± 1.2 mm, 54.6 ± 3.8 mm, respectively. The mean width of Mp was 9.8 ± 1.1 mm. The mean cross section area of Eo-Md (x) was 326.7 ± 67.8 mm². The average length of h and w were 26.5 ± 3.2 and 15.6 ± 2.1 mm, respectively. The use of virtual surgical planning (VSP) to geometrically design the graft was also described. Together with VSP, the anterior ramus bone graft will allow for reconstruction of the mandible with greater surgical efficiency, reduced complexity and without the need for extra-oral bone harvest. This may be an useful alternative in situations where simpler reconstructive procedures are preferred.

Intraoperative Stromal Vascular Fraction Therapy Improves Histomorphometric and Vascular Outcomes in Irradiated Mandibular Fracture Repair

BACKGROUND

Cell-based treatments have demonstrated the capacity to enhance reconstructive outcomes in recent decades but are hindered in clinical utility by regulatory hurdles surrounding cell culture. This investigation examines the ability of a noncultured stromal vascular fraction derived from lipoaspirate to enhance bone healing during fracture repair to further the development of translatable cell therapies that may improve outcomes in irradiated reconstruction.

METHODS

Isogenic male Lewis rats were divided into three groups: fracture, irradiated fracture, and irradiated fracture with stromal vascular fraction treatment. Irradiated groups received a fractioned dose of 35 Gy before mandibular osteotomy. Stromal vascular fraction was harvested from the inguinal fat of isogenic donors, centrifuged, and placed intraoperatively into the osteotomy site. All mandibles were evaluated for bony union and vascularity using micro-computed tomography before histologic analysis.

RESULTS

Union rates were significantly improved in the irradiated fracture with stromal vascular fraction treatment group (82 percent) compared to the irradiated fracture group (25 percent) and were not statistically different from the fracture group (100 percent). Stromal vascular fraction therapy significantly improved all metrics of bone vascularization compared to the irradiated fracture group and was not statistically different from fracture. Osteocyte proliferation and mature bone formation were significantly reduced in the irradiated fracture group. Bone cellularity and maturity were restored to nonirradiated levels in the irradiated fracture with stromal vascular fraction treatment group despite preoperative irradiation.

CONCLUSIONS

Vascular and cellular depletion represent principal obstacles in the reconstruction of irradiated bone. This study demonstrates the efficacy of stromal vascular fraction therapy in remediating these damaging effects and provides a promising foundation for future studies aimed at developing noncultured, cell-based therapies for clinical implementation.

Pre-contoured reconstruction plate fabricated via three-dimensional printed bending support

A mandibular continuity defect can be repaired using either a prosthetic device or autogenous bone. A titanium reconstruction plate can be used with a localized or vascularized flap over the defect of the mandible. Unfortunately, the plate may fail due to plate exposure, screw loosening, fracture, or infection, and will need to be removed. Plate exposure though the skin or mucosa is one of the main reasons for failure. In the present work, the authors introduced a lingually positioned reconstruction plate fabricated via three-dimensional printed bending support. This custom reconstruction plate can avoid plate re-exposure as well as reduce surgical errors and operation time.

Association of Plate Contouring With Hardware Complications Following Mandibular Reconstruction

OBJECTIVES/HYPOTHESIS

Despite considerable effort being dedicated to contouring reconstruction plates, there remains limited evidence demonstrating an association between contour and reconstructive outcomes. We sought to evaluate whether optimizing mandibular reconstruction plate contouring is associated with reduced postoperative hardware complications.

STUDY DESIGN

Retrospective cohort study.

METHODS

A cohort study was performed with adult patients (age ≥18 years) who underwent mandibulectomy and osseous free flap reconstruction following oncologic ablation at the University Health Network in Toronto, Canada, between January 1, 2003 and December 31, 2014. Patients with computed tomography scans performed within 1 year of reconstruction were included. Computer-based three-dimensional models were generated and used to calculate the mean plate-to-bone gap (mm). The primary outcome was plate exposure. Secondary outcome included a composite of plate exposure or intraoral dehiscence. Logistic regression models were fitted for each outcome accounting for other patient and surgical characteristics associated with the primary outcome.

RESULTS

Ninety-four patients met inclusion criteria, with a mean age of 60.4 (standard deviation [SD] 14.9). The mean follow-up time was 31.4 months (range 3-94). Reconstruction was performed with fibular (57%) and scapular free flaps (43%). In the multivariable model, small mean plate-to-bone gap (<1 mm) was independently associated with 86% reduced odds of plate exposure (odds ratio [OR] 0.12; 95% confidence interval [CI] 0.02-0.55). Mean plate-to-bone gap less than 1 mm was also independently associated with reduced odds of developing a composite of plate exposure or intraoral dehiscence (OR, 0.29; 95%CI, 0.11-0.75).

CONCLUSION

Optimizing plate contouring during mandibular reconstruction may decrease the development of postoperative hardware complications.

LEVEL OF EVIDENCE

IV Laryngoscope, 2021.

Improving mandibular reconstruction by using topology optimization, patient specific design and additive manufacturing?-A biomechanical comparison against miniplates on human specimen

In this study, topology optimized, patient specific osteosynthesis plates (TOPOS-implants) are evaluated for the mandibular reconstruction using fibula segments. These shape optimized implants are compared to a standard treatment with miniplates (thickness: 1.0 mm, titanium grade 4) in biomechanical testing using human cadaveric specimen. Mandible and fibula of 21 body donors were used. Geometrical models were created based on automated segmentation of CT-scans of all specimens. All reconstructions, including cutting guides for osteotomy as well as TOPOS-implants, were planned using a custom-made software tool. The TOPOS-implants were produced by electron beam melting (thickness: 1.0 mm, titanium grade 5). The fibula-reconstructed mandibles were tested in static and dynamic testing in a multi-axial test system, which can adapt to the donor anatomy and apply side-specific loads. Static testing was used to confirm mechanical similarity between the reconstruction groups. Force-controlled dynamic testing was performed with a sinusoidal loading between 60 and 240 N (reconstructed side: 30% reduction to consider resected muscles) at 5 Hz for up to 5 · 10⁵ cycles. There was a significant difference between the groups for dynamic testing: All TOPOS-implants stayed intact during all cycles, while miniplate failure occurred after 26.4% of the planned loading (1.32 · 10⁵ ± 1.46 · 10⁵ cycles). Bone fracture occurred in both groups (miniplates: n = 3, TOPOS-implants: n = 2). A correlation between bone failure and cortical bone thickness in mandible angle as well as the number of bicortical screws used was demonstrated. For both groups no screw failure was detected. In conclusion, the topology optimized, patient specific implants showed superior fatigue properties compared to miniplates in mandibular reconstruction. Additionally, the patient specific shape comes with intrinsic guiding properties to support the reconstruction process during surgery. This demonstrates that the combination of additive manufacturing and topology optimization can be beneficial for future maxillofacial surgery.

Objective evaluation of orbito-zygomatic reconstruction with scapular tip free flaps to restore facial projection and orbital volume

BACKGROUND

Restoring anatomical contour and position of the malar eminence and orbital rim following ablative mid-face procedures is critical in maintaining facial contour and orbit position.

OBJECTIVE

To report our reconstructive approach using the scapular tip free-flap (STFF) for orbito-zygomatic defects, evaluating contour and overall shape restoration.

METHODS

The study included 2 series: a clinical cohort of 15 consecutive patients who underwent an orbito-zygomatic reconstruction with a STFF and a cohort of 10 patients who had CT scan imaging but did not have orbito-zygomatic surgical resection or reconstruction. Using a 3D software, overall conformance (OC) and contour conformance (CC) with respect to the mirrored contralateral (clinical cohort) or native zygoma (preclinical cohort) were analyzed. Postoperative orbital volumes were also measured in the clinical cohort. Mean, median, root-mean-square (RMS), minimum and maximum measurements were obtained both for OC and CC. Conformance values of clinical and preclinical cohort were compared to objectively evaluate the quality of reconstruction in terms of orbito-zygomatic framework restoration (Mann-Whitney test).

RESULTS

All measurements for OC and CC between scapular tip and the zygoma showed no differences, both on the clinical (RMS: OC 3.29 mm vs CC 3.32 mm -p = NS-) and preclinical (RMS: OC 2.03 mm and CC 2.31 mm -p = NS-) cohorts. Moreover, there were no differences in post-operative orbital volumes in the clinical cohort. Clinical outcomes of the case-series are also reported.

CONCLUSION

The STFF is highly effective in restoring facial projection and orbital volume in orbito-zygomatic reconstruction.

Risk Factors for Plate Extrusion After Mandibular Reconstruction With Vascularized Free Flap

PURPOSE

Plate extrusion after mandibular reconstruction is a complication that imposes significant morbidity on the patient. The goal of this study is to estimate the incidence of plate extrusion after mandible reconstruction with a vascularized free flap and to identify the factors associated with plate extrusion.

METHODS

This was a retrospective cohort study involving patients who underwent mandibular reconstruction from October 2008 to July 2019 at LAC + USC or Keck Hospital of USC. Inclusion criteria were age ≥ 18 years, single-stage mandibular reconstruction with vascularized free flap, and follow-up of at least 12 months. Relevant demographic, intraoperative, and postoperative data were collected. The primary outcome was postoperative plate extrusion within the 12-month follow-up. Descriptive, univariate, and multivariate analyses were performed. Statistical significance was set at P ≤ .05.

RESULTS

A total of 102 patients were included in this study. The majority received a fibula free flap (90%) for a malignant neoplasm (76%). All patients had at least 12 months of follow-up. The rate of plate extrusion was 16%, with the majority of those patients undergoing plate removal (69%). After adjusting for postoperative fistula, soft tissue, and length of hospitalization, we found that any history of smoking (odds ratio = 12.8; confidence interval, 1.57 to 104.2), number of osteotomies (odds ratio 3.07; confidence interval, 1.09 to 8.6), flap nonviability (odds ratio = 18.2; confidence interval, 2.22 to 148.8) were associated with plate extrusion on multivariate analysis. Postoperative soft tissue infection approached significance.

CONCLUSIONS

This study demonstrates that smoking history, number of osteotomies, and flap nonviability are associated with plate extrusion after mandible reconstruction. Performing fewer osteotomies when possible to avoid excessively small flap bone segments and minimizing postoperative complications may improve long-term outcomes after mandibular reconstruction.

A Comprehensive Analysis of Complications of Free Flaps for Oromandibular Reconstruction

OBJECTIVES/HYPOTHESIS

To determine the frequency and management of short- and long-term complications related to oromandibular free flap reconstruction and identify potentially predictive factors of hardware complications.

STUDY DESIGN

Retrospective chart review.

METHODS

A retrospective database from chart review was formed consisting of 266 oromandibular free flap reconstructions performed at a single institution over a 15-year period. Data were collected on demographics, surgical treatment, complications, and management of complications. Subgroup univariate and multivariate analyses were performed to compare patients with hardware complications and those without.

RESULTS

Eighty-one of 266 patients (30.5%) that underwent oromandibular reconstruction had an early complication (<4 weeks after surgery), and the most common complications were cervical wound dehiscence (11.3%) and fistulas (9.40%). Eighty of 266 patients (30.1%) had a long-term complication (>4 weeks after surgery) and the most common complication was plate exposure (26.7%). Univariate and multivariate analyses showed no association between whether there was hardware extrusion and fibula versus scapula, smoking history, virtual surgical planning (VSP), and dental implantation (P > .05). Only early complications (OR, 3.59, 95% CI, 1.83-7.05, P < .01) and patients undergoing oromandibular reconstruction for osteoradionecrosis (OR, 2.26, 95% CI, 1.10-4.64, P = .03) were strongly and independently associated with subsequent hardware extrusion on univariate analysis.

CONCLUSIONS

Both short- and long-term complications are common after oromandibular reconstruction. The most important predictive factor for a late complication is an early complication and prior radiation. There was no difference of plate complications among the various free flap types. Dental implantation and use of VSP were not associated with hardware complications.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1997-2005, 2021.

LONG-TERM OUTCOMES OF DIFFERENT RECONSTRUCTION OPTIONS USING AUTOGENOUS BONE GRAFT FOR MANDIBULAR RECONSTRUCTION: A RETROSPECTIVE COMPARATIVE STUDY

Background: Several recent studies have attempted to document VBG and NVBG following mandibular reconstruction, mainly the advantages and disadvantages, but very few have specifically evaluated the differences in large parameters including both radiographic and functional aspects for long-term follow-up. However, the object of this study is to compare between two different methods of reconstruction in mandibular defects and to determine the outcomes of different reconstruction options using autogenous vascularized and nonvascularized bone grafts for mandibular reconstruction. Patients and Methods: a total of 39 patients, 22 (56.4%) females and 17 (43.6%) males, with a mean age of 36.41 years at the time of presentation (age ranged for 48 years). Study was performed in two stages at the Department of Head and Neck Surgery - Oral and Maxillofacial oncology. In the First stage (N=39), bone-density, bone resorption, and bone graft failure were examined radiographically on panorex and CBCT. The second stage included functional evaluation (physical examination and questionnaire) based on pain, infection, speech and recurrence. Both groups were followed-up for at least 1month, 6 months and 1 year. Results:the results show significant difference in Pain after one month (p=0.032), radiodensity (p=0.05), bone graft resorption (p=0.03) for 1 year follow-up in favor of the VBG group compared to the NVBG group, there was no statistical difference in bone graft failure, infection, speech and recurrence between the two groups. Conclusion: Vascularized bone graft is the method of choice, especially in extensive malignant defects. On the other hand, novascularized bone graft (81.2% success rate) is a suitable complementary flap for mandible reconstruction mainly in benign and healthy patients. For future studies, large sample size with long-term follow-up more than 1 year will be required to validate our study.

Shape Accuracy and Surface Quality of Additively Manufactured, Optimized, Patient-Specific Bone Plates

Powder-based additive manufacturing technologies such as powder bed fusion (PBF) using a laser beam (PBF-LB) and PBF using an electron beam (PBF-EB) allow the manufacturing of complex, patient-specific implants from titanium alloys at appropriate manufacturing expenses and thus production cost. To meet medical quality requirements, mechanical post-treatment (e.g., grinding and polishing) is often required. However, different medical applications require specific quality characteristics. It is therefore necessary to assess the fulfillment of the requirements for each case individually with regard to the manufacturing technologies. This study investigated the potential of the two mentioned additive manufacturing technologies for manufacturing patient-specific, topology-optimized bone plates that are used for osteosynthesis (the joining of bone segments) in the reconstruction of the mandible (lower jaw). Identical individualized implants were manufactured and subsequently treated with established industrial processes and examined according to medical quality requirements. Crucial quality requirements for this medical application are the shape accuracy (for exact bone positioning and even load transmission) as well as the surface quality (to enhance fatigue strength and prevent bone ingrowth in view of the subsequent easy removal of the plates). The machining of the implants is shown in comparison to distinguish the two manufacturing processes from established procedures.

Islanded facial artery osteomyomucosal/osseous flap in head and neck reconstruction

A local pedicled vascularized bone flap can prevent the morbidity and cost of free bone flap surgery in small segmental bone defects or long cartilaginous defects of the head and neck. Such flaps can also be useful in patients who are high risk for surgery. The periosteal vascularity of the mandible can be used to design islanded facial artery-based bone flaps, which can be utilized to that extent. Two patients with a small segmental mandibulectomy defect and one patient with a long cricotracheal resection defect underwent reconstruction using three different designs of islanded facial artery osteomyomucosal/osseous flap (iFOMM). The patients had a minimum follow-up period of 18 months. All flaps were successful, with satisfactory healing and without any functional deficit or disease at last follow-up.

Safety of boneless reconstruction of the mandible with a CAD/CAM designed titanium device: The replica cohort study

OBJECTIVE

We evaluated the safety of REPLICA, a CAD/CAM-designed patient-specific titanium mandible, in patients with mandibular defects not suitable for reconstruction with traditional techniques.

PATIENTS AND METHODS

We performed a cohort study with a composite primary outcome assigned at the end of a 1-year follow-up. The outcome was assigned in the presence of all the following: 1) absence of intraoral or skin extrusion of REPLICA; 2) decrease or cessation of oral pain; 3) stability or increase in mouth opening; 4) resumption of oral feeding without the need of nasogastric tube; 5) absence of fracture at multidetector computer tomography (MDCT); 6) absence of displacement (MDCT); 7) absence of screw loosening (MDCT). The secondary outcome was the patient-reported QOL at 6 months of follow-up as detected by the EORTC QLQ-C30 and QLQ-H&N35 questionnaires.

RESULTS

Between March 2012 and June 2017, 18 consecutive patients, with a median (IQR) age of 67 (65;74) underwent reconstruction of mandibular defects with REPLICA at our Unit. The primary outcome was reached by 14 of the 18 patients. QOL data were available for 15 patients at the 6-month follow-up, showing a good profile of general and disease-specific QOL.

CONCLUSION

REPLICA offered a safe solution at 1-year for the treatment of mandibular defects not suitable for reconstruction with traditional techniques, and was associated with subjective well-being and satisfaction. Further studies are needed to assess the full range of indications of REPLICA.

Complication of osteo reconstruction by utilizing free vascularized fibular bone graft

The success of free vascularized fibular bone graft (FVFBG) has accelerated the osteo reconstruction which results from trauma, resection of a tumor or an infectious bone segment, or correction of congenital deformity. But the complication behind should not be overlooked. The failure could necessitate a second surgery, which prolong the rehabilitation period and produce further health cost. Worst, the patients may suffer a permanent impaired ankle function, or a sustained morpho-functional loss on reconstructive area which are hard to save. To provide an overview of the complication related to reconstruction by FVFBG, a narrative review is conducted to identify the complications including their types and rates, the contributing factors, the approaches to measure and the techniques to avoid. Methodologically, by quick research on Pubmed and abstract reading of reviews, we characterize five reconstructive areas where FVFBG were most frequently applied: extremities, mandible, spine, osteonecrosis of femoral head, and penile. Following, the complications on different reconstructive areas are retrieved, studied and presented in five (or more specifically, six) separate sections. By the way, meaningful difference between FVFBG and other bone flap was presented in a few words if necessary. Donor-site morbidities were studied and summarized as a whole. In these literatures, the evidences documented on limb and mandibular reconstruction have the fullest detail, followed by the spine and lastly the penile. In conclusion, FVFBG, though a mature technique, needs further deep and comprehensive study and maybe device-based assistance to achieve better reconstructive effect and minimize donor-site damage.

Novel finite element-based plate design for bridging mandibular defects: Reducing mechanical failure

INTRODUCTION

When the application of a free vascularised flap is not possible, a segmental mandibular defect is often reconstructed using a conventional reconstruction plate. Mechanical failure of such reconstructions is mostly caused by plate fracture and screw pull-out. This study aims to develop a reliable, mechanically superior, yet slender patient-specific reconstruction plate that reduces failure due to these causes.

PATIENTS AND METHODS

Eight patients were included in the study. Indications were as follows: fractured reconstruction plate (2), loosened screws (1) and primary reconstruction of a mandibular continuity defect (5). Failed conventional reconstructions were studied using finite element analysis (FEA). A 3D virtual surgical plan (3D-VSP) with a novel patient-specific (PS) titanium plate was developed for each patient. Postoperative CBCT scanning was performed to validate reconstruction accuracy.

RESULTS

All PS plates were placed accurately according to the 3D-VSP. Mean 3D screw entry point deviation was 1.54 mm (SD: 0.85, R: 0.10-3.19), and mean screw angular deviation was 5.76° (SD: 3.27, R: 1.26-16.62). FEA indicated decreased stress and screw pull-out inducing forces. No mechanical failures appeared (mean follow-up: 16 months, R: 7-29).

CONCLUSION

Reconstructing mandibular continuity defects with bookshelf-reconstruction plates with FEA underpinning the design seems to reduce the risk of screw pull-out and plate fractures.

Biomechanical In Vitro Study on the Stability of Patient-Specific CAD/CAM Mandibular Reconstruction Plates: A Comparison Between Selective Laser Melted, Milled, and Hand-Bent Plates

Study Design

An experimental in vitro study.

Objective

Plate fractures are a recurrent problem in alloplastic mandibular reconstruction. Hypothetically it can be assumed that computer-aided design (CAD)/computer-aided manufacturing (CAM) reconstruction plates have a higher stability than conventional hand-bent plates. The aim of the study was to compare additive and subtractive fabricated CAD/CAM mandibular reconstruction plates as well as conventional plates with regard to their biomechanical properties.

Methods

In a chewing simulator, plates of 2 conventional locking plate systems and 2 CAD/CAM-fabricated plate systems were compared. The plates were loaded in a fatigue test. The maximum number of cycles until plate fracture and the plate stiffness were compared.

Results

While all conventional plates fractured at a maximum load between 150 and 210 N (Newton) after a number of cycles between 40 000 and 643 000, none of the CAD/CAM plates broke despite a nearly doubled load of 330 N and 2 million cycles. Both CAD/CAM systems proved to be significantly superior to the hand-bent plates. There was no difference between the 2 CAD/CAM systems.

Conclusions

Concerning the risk of plate fracture, patient-specific CAD/CAM reconstruction plates appear to have a significant advantage over conventional hand-bent plates in alloplastic mandibular reconstruction.

Patient-specific finite element models of the human mandible: Lack of consensus on current set-ups

The use of finite element analysis (FEA) has increased rapidly over the last decennia and has become a popular tool to design implants, osteosynthesis plates and prostheses. With increasing computer capacity and the availability of software applications, it has become easier to employ the FEA. However, there seems to be no consensus on the input variables that should be applied to representative FEA models of the human mandible. This review aims to find a consensus on how to define the representative input factors for a FEA model of the human mandible. A literature search carried out in the PubMed and Embase database resulted in 137 matches. Seven papers were included in this current study. Within the search results, only a few FEA models had been validated. The material properties and FEA approaches varied considerably, and the available validations are not strong enough for a general consensus. Further validations are required, preferably using the same measuring workflow to obtain insight into the broad array of mandibular variations. A lot of work is still required to establish validated FEA settings and to prevent assumptions when it comes to FEA applications.

A small number of residual teeth after the mandibular resection of oral cancer is associated with titanium reconstruction plate exposure

Objective

Reconstruction plates are used to treat patients with a segmental mandibular defect after oral cancer surgery. Reconstruction plate failure analysis has rarely focused on occlusion, which conducts a mechanical force to the mandible and the plate. To determine the prognostic factors, we retrospectively evaluated patients who underwent reconstruction of a mandibular segmental defect with a reconstruction plate and assessed the number of residual paired teeth.

Material and Methods

From among 390 patients with oral cancer who visited University of Tsukuba Hospital (Tsukuba, Japan) between 2007 and 2017, we selected and analyzed the data of 37 patients who underwent segmental resection of the mandible and reconstruction with reconstruction plates. Prognostic factors evaluated were patient age, sex, TNM classification, plate manufacturer, treatment with radiotherapy or chemotherapy, whether the patient had diabetes or smoked, and whether the patient had a small number of residual paired teeth, plate length, and use of a fibular‐free flap. Among these 37 patients, eight reconstruction plates had intraoral or extraoral exposure and were removed in 5 years.

Results

Kaplan–Meier and log‐rank analyses revealed that the prognosis for the 5‐year plate exposure‐free rate was significantly poorer for patients with a small number of residual teeth than for patients with no teeth or those with a large number of residual teeth (.01). Univariate Cox regression analysis revealed that a small number of residual teeth was a significant prognostic factor in the loss of a reconstruction plate (hazard ratio: 5.63; 95% confidence interval [1.10, 25.85]; .04).

Conclusions

A small number of residual teeth after the segmental resection of oral cancer is significantly involved in reconstruction plate survival and may be important in predicting reconstruction plate prognosis.

Nonvascularized Iliac Bone Reconstruction for the Mandible Without Maxillofacial Skin Scarring

PURPOSE

There are many methods to reconstruct the mandible, but they are often accompanied by trauma, which can lead to scarring of the maxillofacial skin. The purpose of this study was to show the utility of a minimally invasive method for reconstruction of the mandible with nonvascularized iliac bone grafts without a skin scar, as well as to evaluate the success rate and complications.

PATIENTS AND METHODS

This was a retrospective case series. We retrospectively analyzed patients who underwent transoral resection of benign mandibular pathologies, followed by nonvascularized iliac bone graft reconstruction. The primary outcome variable was the success rate of the bone grafts. Secondary outcome variables were postoperative complications at the grafted bone recipient and donor sites, the long-term absorptivity of grafted bone, and the type of mandibular defect. We computed descriptive statistics or performed the χ² test for each variable.

RESULTS

Overall, 54 patients were included in the study, including 21 male and 33 female patients, with an age range of 10 to 65 years. The complete survival rate was 87.0% (47 of 54 patients), and the partial survival rate was 98.1% (53 of 54). The average bone absorption rate 3 years after surgery was 1.8 to 30.7%. We propose a new classification method for mandibular defects based on the extent of the tumor, location of the osteotomy, and degree of surgical difficulty.

CONCLUSIONS

Intraoral nonvascularized iliac bone grafting is a highly successful minimally invasive method for mandibular reconstruction. It is also one of the best methods for mandibular reconstruction in patients with benign mandibular tumors without soft tissue involvement.

An In Vivo Evaluation of Biocompatibility and Implant Accuracy of the Electron Beam Melting and Commercial Reconstruction Plates

The use of additive manufacturing in medical applications has become more prevalent over the last decade. Studies have proved that reconstruction plates with a mesh structure enhance the biocompatibility and bone-ingrowth formation. However, limited studies have been reported in the customization and in vivo clinical assessment of mesh implants. The purpose of this study was to investigate the surgical treatment and implant fitting accuracy using three different reconstruction plates. Fifteen goats were divided into one control and three experimental groups (Groups 1, 2, and 3) with five in each group. An experimental segmental defect was created on these animals and was adopted with customized electron beam melting reconstruction titanium plates with mesh in Group 1 and without mesh in Group 2 and commercial reconstruction plate in Group 3. All the animals were subjected to radiographic analysis before and after surgery. The subjected animals were sacrificed after 3 months and the electron beam melting reconstruction plates were compared with the commercial plate based on clinical and histology analysis and implant fitting accuracy. Both the electron beam melting reconstruction plates (with mesh and without mesh) and commercial plates survived the three months post-operation, revealing good wound-healing with new bone formation and without any foreign-body reaction. The electron beam melting reconstructed plate with mesh (Group 1) was found to have a better implant fitting when compared to the other two groups. The average discrepancy between Groups 2 and 3 was not significant. Certainly, the commercial plate (Group 3) was found to have the least accuracy as compared to other electron beam melting reconstruction plates (Group 1 and Group 2). Custom design electron beam melting fabricated reconstruction plates possessed better functionality, aesthetic outcome, and long-term biocompatibility when compared to commercial plates. Animal results indicated that the electron beam melting plates with mesh (Group 1) were superior in comparison to the other two groups due to its ability to provide better bone-in-growth and osseointegration on its porous microstructure.

Partial mandibulectomy without bony reconstruction in patients with oropharyngeal or mouth cancer

Aim of the study

Resection of tumours of the oral cavity has significant consequences relating to function and aesthetic properties. Advancements in surgical techniques and microvascular surgery have enabled reconstructive outcomes to reach those of pre-surgery levels with good functional and aesthetic results. However, reconstructive options are not without complications.

Material and methods

We report the outcome of 23 patients with large tumours of the oral cavity or floor of the mouth, who underwent resection of the tumour and parts of the mandible without bony reconstruction. The patient population consisted of 19 oropharyngeal carcinomas and four floor of the mouth cancers, all of which had stage cT4 (six female and 17 male patients), and with an average patient age of 59.8 years. The pre- and postoperative ability to open the mouth, level of pain while masticating, mastication function pre and post-surgery, and the aesthetic outcome post-surgery were measured.

Results

The results obtained were deemed pleasantly acceptable by the patients, from aesthetic, functional, and analgesic points of view.

Discussion

A thorough preoperative work up is required and discussion with a multidisciplinary team is a necessity. This treatment option is more acceptable to the patient than would be expected and provides a satisfactory functional and aesthetic outcome. Therefore, we believe that partial mandibulectomy without bony reconstruction is an acceptable management option for a carefully selected group of patients who may not be suitable for the extensive surgery involved with bony reconstruction.

Nonvascularized Bone Graft Reconstruction of the Irradiated Murine Mandible: An Analogue of Clinical Head and Neck Cancer Treatment

Nonvascularized bone grafts (NBGs) represent a practical method of mandibular reconstruction that is precluded in head and neck cancer patients by the destructive effects of radiotherapy. Advances in tissue-engineering may restore NBGs as a viable surgical technique, but expeditious translation demands a small-animal model that approximates clinical practice. This study establishes a murine model of irradiated mandibular reconstruction using a segmental iliac crest NBG for the investigation of imperative bone healing strategies. Twenty-seven male isogenic Lewis rats were divided into 2 groups; control bone graft and irradiated bone graft (XBG). Additional Lewis rats served as graft donors. The XBG group was administered a fractionated dose of 35Gy. All rats underwent reconstruction of a segmental, critical-sized defect of the left hemi-mandible with a 5 mm NBG from the iliac crest, secured by a custom radiolucent plate. Following a 60-day recovery period, hemi-mandibles were evaluated for bony union, bone mineralization, and biomechanical strength (P < 0.05). Bony union rates were significantly reduced in the XBG group (42%) compared with controls (80%). Mandibles in the XBG group further demonstrated substantial radiation injury through significant reductions in all metrics of bone mineralization and biomechanical strength. These observations are consistent with the clinical sequelae of radiotherapy that limit NBGs to nonirradiated patients. This investigation provides a clinically relevant, quantitative model in which innovations in tissue engineering may be evaluated in the setting of radiotherapy to ultimately provide the advantages of NBGs to head and neck cancer patients and reconstructive surgeons.

Nonvascularized Bone Grafts for Reconstruction of Segmental Mandibular Defects: Is Length of Graft a Factor of Success?

PURPOSE

The purpose of this study was to evaluate a long-debated question in the field of whether the success of reconstructing mandibular defects with nonvascularized bone grafts (NVBGs) is dependent on the length of the graft.

MATERIALS AND METHODS

The inclusion criteria were patients who had received NVBGs, such as anterior or posterior iliac crest and costochondral grafts, to reconstruct segmental defects of the mandible between 2008 and 2017 at the Department of Oral and Maxillofacial Surgery at Case Western Reserve University. Patients with a history of irradiation of the head and neck and patients with inadequate follow-up were excluded from this study. Data such as defect length, patient age, comorbidities, length of follow-up, location of defect, etiology of defect, and postoperative course were collected. Success was judged by radiographic and clinical evidence of bone continuity and stability at a minimum of 4 months postoperatively. Failures were considered loss of all or part of the graft, resulting in a residual continuity defect requiring further bone grafting.

RESULTS

We identified 61 potential cases, of which 29 met the inclusion and exclusion criteria. The mean age of the patients at the time of grafting was 55 years (range, 17 to 81 years), with a mean follow-up length of 18 months. The length of defects ranged from 2 to 22 cm. The grafts were 6 cm or less in length in 7 defects and greater than 6 cm in length in 22 defects. All cases were grafted at a minimum of 6 months after resection, and bone morphogenetic protein was used in 25 cases (86%). Failure occurred in 1 patient in the group with grafts of 6 cm or less and 2 patients in the group with grafts greater than 6 cm, corresponding to success rates of 86% and 91%, respectively. Eight patients experienced minor complications such as wound dehiscence or infection, which resolved with local measures and antibiotics.

CONCLUSIONS

The results of our study show that NVBGs are a viable, safe, and effective treatment option for segmental mandibular defects over 6 cm in length in non-irradiated patients.

Establishment of a Numerical Model to Design an Electro-Stimulating System for a Porcine Mandibular Critical Size Defect

Electrical stimulation is a promising therapeutic approach for the regeneration of large bone defects. Innovative electrically stimulating implants for critical size defects in the lower jaw are under development and need to be optimized in silico and tested in vivo prior to application. In this context, numerical modelling and simulation are useful tools in the design process. In this study, a numerical model of an electrically stimulated minipig mandible was established to find optimal stimulation parameters that allow for a maximum area of beneficially stimulated tissue. Finite-element simulations were performed to determine the stimulation impact of the proposed implant design and to optimize the electric field distribution resulting from sinusoidal low-frequency ( f = 20 Hz ) electric stimulation. Optimal stimulation parameters of the electrode length h el = 25 m m and the stimulation potential φ stim = 0.5 V were determined. These parameter sets shall be applied in future in vivo validation studies. Furthermore, our results suggest that changing tissue properties during the course of the healing process might make a feedback-controlled stimulation system necessary.

Composite Nanofibers Containing Multiwall Carbon Nanotubes as Biodegradable Membranes in Reconstructive Medicine

We have tested titanium (Ti) plates that are used for bone reconstruction in maxillofacial surgery, in combination with five types of novel long-resorbable biomaterials: (i) PCL₀-polycaprolactone without additives, (ii) PCLMWCNT-polycaprolactone with the addition of multiwall carbon nanotubes (MWCNT), (iii) PCLOH-polycaprolactone doped with multiwall carbon nanotubes (MWCNT) containing ⁻OH hydroxyl groups, (iv) PCLCOOH-polycaprolactone with the addition of multiwall carbon nanotubes (MWCNT) containing carboxyl groups, and (v) PCLTI-polycaprolactone with the addition of Ti nanoparticles. The structure and properties of the obtained materials have been examined with the use of Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and/or X-ray powder diffraction (XRD). Titanium BR plates have been covered with: (i) PCL₀ fibers (PCL0BR-connection plates), (ii) PCLMWCNT fibers (PCLMWCNTBR-plates), (iii) PCLOH fibers (PCLOHBR-plates), (iv) PCLCOOH (PCLCOOHBR-plates), (v) PCLTI fiber (PCLTIBR-connection plates). Such modified titanium plates were exposed to X-ray doses corresponding to those applied in head and neck tumor treatment. The potential leaching of toxic materials upon the irradiation of such modified titanium plates, and their effect on normal human dermal fibroblasts (NHDF) have been assessed by MTT assay. The presented results show variable biological responses depending on the modifications to titanium plates.

Triple primary cancer of the head and neck, skin and prostate: A case report and literature review

Second primary cancer (SPC) is an important prognostic factor for patients with head and neck cancer (HNC); therefore, the association between the prognosis and development of SPC has been well-reported. The use of 2-[18F]-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) is valuable to examine cancer stage, evaluate treatment responses and investigate suspected relapses or metastases. In the present study, the case of a male patient who was diagnosed with three primary cancer types, including well to moderately differentiated squamous cell carcinoma (SCC) of the mandible, axillary cutaneous poorly differentiated SCC and prostate adenocarcinoma, was described. Among these, mandible cancer was the first diagnosed when the patient was 70 years of age. Synchronous skin and prostate cancer (PRC) types then developed 3 years later. To the best of our knowledge, this is the first report of the aforementioned combination of cancer types. Postoperative FDG-PET was not performed as no lesions of recurrence or metastases of mandible cancer were found. Three years later, the PRC was asymptomatic and was incidentally detected by FDG-PET performed for a preoperative evaluation of skin cancer. It was indicated that FDG-PET could be utilized in patients with HNC due to there being no accurate FDG-PET protocol to detect SPC over a long-term follow-up.

Non-vascularised fibular bone graft after vascular crisis: compensation for the failure of vascularised fibular free flaps

After reconstruction of a segmental mandibular defect with a fibular free flap, a vascular crisis can be detected clinically and a "no-flow" phenomenon found during re-exploration. Traditional methods used to solve this include removal of the failed flap and delayed mandibular reconstruction, or restoration of the defect with a functional reconstruction plate or contralateral fibular free flap. Our aim therefore was to investigate under what circumstances it is feasible to use a non-vascularised fibular bone graft (NVFB) as a free bone graft after the failure of a vascularised fibular free flap. From 1 January 2010-31 December 2014, 10 patients who had NVFB after failure of a fibular free flap were included in the study. All patients were treated at the Peking University School and Hospital of Stomatology. NVFB were preserved successfully without infection in all 10 cases, and follow-up imaging showed that it had incorporated well with the residual mandible, the basic function and facial aesthetics of which were maintained. In conclusion we have identified that by precise selection of patients, detailed preoperative planning, and meticulous postoperative care, NVFB can be used as a "rescue" technique after failure of a fibular free flap, and can successfully restore the segmental mandibular defect and facial contour.