Three-Dimensionally Printed Patient-Specific Surgical Plates Increase Accuracy of Oncologic Head and Neck Reconstruction Versus Conventional Surgical Plates: A Comparative Study

Controversies in point-of-care 3D printing for oncological and reconstructive surgery with free software in oral and maxillofacial surgery: European regulations, costs, and timeframe

The aim of this paper is to discuss the controversies surrounding the most recent European regulations, as well as the cost, for a 3D printing workflow using free-source software in the context of a tertiary level university hospital in the Spanish public health system. Computer-aided design and manufacturing (CAD/CAM) for head and neck oncological surgery with the printing of biomodels, cutting guides, and patient-specific implants has made it possible to simplify and make this type of highly complex surgery more predictable. This technology is not without drawbacks, such as increased costs and the lead times when planning with the biomedical industry. A review of the current European legislation and the literature on this subject was performed, and comparisons made with the authors' in-house 3D printing setup using free software and different 3D printers. The cost analysis revealed that for the cheapest setup with free software, it would be possible to amortize the investment from case 2, and in all cases the initial investment would be amortized before case 9. The timeframe ranged from 2 weeks with the biomedical industry to 72 h with point-of-care 3D printing. It is now possible to develop point-of-care 3D printing in any hospital with almost any budget.

Precise maxillofacial soft tissue reconstruction: A combination of cone beam computed tomography and 3dMD photogrammetry system

Introduction

The reconstruction of both extra- and intra-oral soft tissue defects, particularly in restoring the morphology of the lip and the corners of the mouth, has posed a significant challenge for surgeons. Inappropriate methods often lead to maxillofacial deformity which then causes psychological and functional problems. This study aimed to address the challenge of reconstructing extensive and complex maxillofacial soft tissue defects, mainly focusing on the lip, the corners of the mouth, and the surrounding areas.

Materials and methods

We developed a reconstruction approach by combining the 3dMDface System (3dMD) with the cone beam computed tomography (CBCT). Firstly, with the extra-oral incision line, we evaluated the shape and the size of the extra-oral defect with 3dMD digitally. Then we used the corresponding maxillary and mandible tooth positions to record the intra-oral defect, which was then converted to digital images by combining 3dMD and CBCT. The islands of the anterolateral thigh perforator flap were then designed after the locations of the perforators were detected with Doppler ultrasonography.

Results

A clinical case diagnosed as dermatofibrosarcoma protuberans was presented to illustrate the approach. The patient's tumor resection and the size of multiple defects were measured and simulated via the virtual surgery system. A three-island perforator flap from the descending branch of the lateral femoral circumflex artery was designed accurately. Two weeks postoperatively, the flap was healed as anticipated and the patient was satisfied with the profile.

Conclusion

The combination of the 3dMD and CBCT technologies improves the accuracy and fitness of extra- and intra-oral soft tissue reconstruction.

Long-term stability of jaw reconstruction with microvascular bone flaps: A prospective longitudinal study

OBJECTIVES

Microvascular bone flap jaw reconstruction has achieved satisfactory clinical outcomes. However, little is known about the long-term stability of the reconstructed jaw. This prospective longitudinal study aimed to investigate the long-term stability of jaw reconstruction and factors that were associated with it.

METHODS

Patients with successful computer-assisted osseous free-flap jaw reconstruction in the Department of Oral and Maxillofacial Surgery, Queen Mary Hospital, Hong Kong were recruited for this prospective longitudinal study. The three-dimensional jaw models at the pre-operative plan, post-operative 1-month, and 2 years were aligned and compared.

RESULTS

A total of 69 patients were recruited, among which 48 patients were available for the long-term analysis. Compared to 1-month after surgery, further deviation from the pre-operative plan was observed at post-operative 2 years. Lack of accuracy in surgery, segmental mandible resection especially with the involvement of mandible angles, and post-operative radiation therapy were identified as the significant factors affecting the positional stability of the reconstructed jaw (p < 0.05). Stable reconstruction was observed in the subgroup analysis of patients without post-operative radiation therapy.

CONCLUSION

Up to the best of our knowledge, this is the first prospective longitudinal study reporting the long-term stability of jaw reconstruction and its affecting factors. Our data demonstrated that the reconstructed jaw position lacked stability over the postoperative period. How to improve long-term stability of reconstructed jaw thus optimize the functional outcomes warrants further studies.

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.

Deep Circumflex Iliac Artery Flap Reconstruction in Brown Class I Defect of the Mandible Using a Three-Component Surgical Template System

BACKGROUND

Computer-assisted surgery is widely used in mandibular reconstruction, but the process is not well described for cases using the deep circumflex iliac artery flap (DCIA) as the donor site. This study aimed to present a DCIA-based three-component surgical template system (3-STS) in patients with a mandibular Brown class I defect.

METHODS

This retrospective cohort study compared clinical outcomes of mandibular reconstruction with DCIA flap using 3-STS or conventional surgical templates. The primary outcome of the study was the accuracy of reconstruction, and the secondary outcomes included surgical time and bone flap ischemia time. Surgery-related parameters and functional outcomes were also recorded and compared.

RESULTS

Forty-four patients (23 in the 3-STS group and 21 in the control group) between 2015 and 2021 were included. Compared with the control group, the 3-STS group had higher accuracy of reconstruction, indicated by lower deviation in absolute distance (1.45 ± 0.76 mm versus 2.02 ± 0.89 mm; P = 0.034), and less deviation in coronal and sagittal angles (0.86 ± 0.53 degree versus 1.27 ± 0.59 degrees, P = 0.039; and 2.52 ± 1.00 degrees versus 3.25 ± 1.25 versus, P = 0.047) between preoperative and postoperative computed tomographic imaging. Surgical time and bone flap ischemia time were significantly reduced in the 3-STS group compared with the control group (median time, 385 minutes versus 445 minutes and 32 minutes versus 53 minutes, respectively; P < 0.001). In addition, masseter attachment was preserved in the 3-STS group but not in the control group. No differences were found in adverse events or other clinical variables.

CONCLUSION

The 3-STS can improve accuracy, simplify intraoperative procedures to increase surgical efficiency, and preserve functionality in mandibular reconstruction for Brown class I defects.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

3D Printing Applications for Craniomaxillofacial Reconstruction: A Sweeping Review

The field of craniomaxillofacial (CMF) surgery is rich in pathological diversity and broad in the ages that it treats. Moreover, the CMF skeleton is a complex confluence of sensory organs and hard and soft tissue with load-bearing demands that can change within millimeters. Computer-aided design (CAD) and additive manufacturing (AM) create extraordinary opportunities to repair the infinite array of craniomaxillofacial defects that exist because of the aforementioned circumstances. 3D printed scaffolds have the potential to serve as a comparable if not superior alternative to the "gold standard" autologous graft. In vitro and in vivo studies continue to investigate the optimal 3D printed scaffold design and composition to foster bone regeneration that is suited to the unique biological and mechanical environment of each CMF defect. Furthermore, 3D printed fixation devices serve as a patient-specific alternative to those that are available off-the-shelf with an opportunity to reduce operative time and optimize fit. Similar benefits have been found to apply to 3D printed anatomical models and surgical guides for preoperative or intraoperative use. Creation and implementation of these devices requires extensive preclinical and clinical research, novel manufacturing capabilities, and strict regulatory oversight. Researchers, manufacturers, CMF surgeons, and the United States Food and Drug Administration (FDA) are working in tandem to further the development of such technology within their respective domains, all with a mutual goal to deliver safe, effective, cost-efficient, and patient-specific CMF care. This manuscript reviews FDA regulatory status, 3D printing techniques, biomaterials, and sterilization procedures suitable for 3D printed devices of the craniomaxillofacial skeleton. It also seeks to discuss recent clinical applications, economic feasibility, and future directions of this novel technology. By reviewing the current state of 3D printing in CMF surgery, we hope to gain a better understanding of its impact and in turn identify opportunities to further the development of patient-specific surgical care.

Patient-specific distractors for customized mandibular distraction osteogenesis to relieve upper airway obstruction in infants with Pierre Robin sequence

The purpose of this article is to report the author's technique for using patient-specific distractors for customized distraction osteogenesis of the mandible in patients with Pierre Robin sequence and upper airway obstruction. The advantages of virtual planning and patient-specific plates in other aspects of craniomaxillofacial surgery, such as orthognathic and reconstructive surgery, have been reported previously. Similar to patient-specific plates, the theorized advantages of patient-specific distractors in infants with Robin sequence and upper airway obstruction include increased accuracy, decreased operating time, and less morbidity to vital anatomic structures such as the inferior alveolar nerve and developing tooth buds. This technique is novel in using patient-specific distractors in the craniomaxillofacial skeleton.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Virtual Surgical Planning and Three-Dimensional Models for Precision Sinonasal and Skull Base Surgery

Sinonasal and skull base malignancies represent a rare, heterogenous group of pathologies with an incidence of 0.556 per 100,000 persons in the population. Given the numerous critical anatomic structures located adjacent to the sinonasal cavity and skull base, surgery for tumors in this region requires careful pre-operative planning with the assistance of radiological imaging and intraoperative image guidance technologies to reduce the risk of complications. Virtual surgical planning (VSP) and three-dimensional models (3DMs) are adjunctive technologies which assist clinicians to better visualize patient anatomy using enhanced digital radiological images and physical stereolithographic models based on patients' personal imaging. This review summarizes our institutional experience with VSP and 3DMs in sinonasal and skull base surgical oncology. A clinical case series is used to thematically illustrate the application of VSP and 3DMs in surgical ablation, reconstruction, patient communication, medical education, and interdisciplinary teamwork in sinonasal and skull base surgery.

Evolution of Medical Modeling and 3D Printing in Microvascular Midface Reconstruction: Literature Review and Experience at MD Anderson Cancer Center

Reconstruction of the midface represents a challenge for reconstructive microsurgeons given the formidable task of restoring both aesthetics and functionality. In particular, preservation of proper globe positioning and maintaining normal vision are as important as restoring the proper projection of the midface and enabling a patient to speak and eat as normally as possible. The introduction of virtual surgical planning (VSP) and medical modeling has revolutionized bony reconstruction of the craniofacial skeleton; however, the overwhelming majority of studies have focused on mandibular reconstruction. Here, we introduce some novel advances in utilizing VSP for bony reconstruction of the midface. The present review aims (1) to provide a review of the literature on the use of VSP in midface reconstruction and (2) to provide some insights from the authors' early experience.

Patient-specific 3D-printed mini-versus reconstruction plates for free flap fixation at the mandible: Retrospective study of clinical outcomes and complication rates

This study aimed to compare the clinical outcomes and complication rates of patient-specific 3D-printed mini- and reconstruction plates for free flap fixation in mandibular reconstruction. A retrospective monocentric study was carried out between April 2017 and December 2021 to analyze patients undergoing immediate mandibular reconstruction using fibula free flaps and osteosynthesis using patient-specific 3D-printed implants. Eighty-three patients with a mean age of 63.6 years were included. The mean follow-up period was 18.5 months. Patient-specific 3D-printed plates were designed as reconstruction plates (38 patients), miniplates (21 patients) or a combination of reconstruction- and miniplates (24 patients). With miniplates, plate removal was performed significantly more often via an intraoral approach (p < 0.001) and in an outpatient setting (p = 0.002). Univariate analysis showed a higher fistula rate with reconstruction plates (p = 0.037). Multivariate analysis showed no significant differences in complications. Case-control matching demonstrated significantly lower rates of fistula (p = 0.017) and non-union (p = 0.029) in the combined group. This retrospective study shows a tendency towards reduced complication rates with patient-specific 3D-printed miniplates in comparison to patient-specific 3D-printed reconstruction plates for immediate mandibular reconstruction with fibula free flaps.

Changes in condylar position and morphology after mandibular reconstruction by vascularized fibular free flap with condyle preservation

OBJECTS

Changes in condylar position and morphology after mandibular reconstruction are important to aesthetic and functional rehabilitation. We evaluated changes in condylar position and morphology at different stages after mandibular reconstruction using vascularized fibular free flap with condyle preservation.

MATERIALS AND METHODS

A total of 23 patients who underwent mandibular reconstruction with fibular flap were included in this retrospective study. CT data of all patients were recorded before surgery (T0), 7 to 14 days after surgery (T1), and at least 6 months after surgery (T2). Five parameters describing the condylar position and 4 parameters describing the morphology were measured in sagittal and coronal views of CT images. The association between clinical characteristics and changes in condylar position and morphology was analyzed. A finite element model was established to investigate the stress distribution and to predict the spatial movement tendency of the condyle after reconstruction surgery.

RESULTS

The condylar position changed over time after mandibular reconstruction. The ipsilateral condyles moved inferiorly after surgery (T0 to T1) and continually move anteriorly, inferiorly, and laterally during long-term follow-up (T1 to T2). Contrary changes were noted in the contralateral condyles with no statistical significance. No morphological changes were detected. The relationship between clinical characteristics and changes in condylar position and morphology was not statistically significant. A consistent result was observed in the finite element analysis.

CONCLUSION

Condylar positions showed obvious changes over time after mandibular reconstruction with condylar preservation. Nevertheless, further studies should be conducted to evaluate the clinical function outcomes and condylar position.

CLINICAL RELEVANCE

These findings can form the basis for the evaluation of short-term and long-term changes in condylar position and morphology among patients who have previously undergone mandibular reconstruction by FFF with condyle preservation.

The Effectiveness of Three-Dimensional Osteosynthesis Plates versus Conventional Plates for the Treatment of Skeletal Fractures: A Systematic Review and Meta-Analysis

PURPOSE

To assess the difference between preformed anatomically shaped osteosynthesis plates and patient-specific implants versus conventional flat plates for the treatment of skeletal fractures in terms of anatomical reduction, operation time, approach, patient outcomes, and complications.

MATERIAL AND METHODS

MEDLINE (1950 to February 2023), EMBASE (1966 to February 2023), and the Cochrane Central Register of Controlled Trials (inception to February 2023) databases were searched. Eligible studies were randomised clinical trials, prospective controlled clinical trials, and prospective and retrospective cohort studies (n ≥ 10). Inclusion criteria were studies reporting the outcomes of preformed anatomically shaped osteosynthesis plates and patient-specific implants versus conventional flat plates after treating skeletal fractures. Outcome measures included anatomical reduction, stability, operation time, hospitalisation days, patients' outcomes, and complications. Two independent reviewers assessed the abstracts and analysed the complete texts and methodologies of the included studies.

RESULTS

In total, 21 out of the 5181 primarily selected articles matched the inclusion criteria. A meta-analysis revealed a significant difference in operation time in favour of the preformed anatomical plates and patient-specific implants versus conventional plates. Significant differences in operation time were found for the orbital (95% CI: -50.70-7.49, p = 0.008), upper limb (95% CI: -17.91-6.13, p < 0.0001), and lower limb extremity groups (95% CI: -20.40-15.11, p < 0.00001). The mean difference in the rate of anatomical reduction in the lower limb extremity group (95% CI: 1.04-7.62, p = 0.04) was also in favour of using preformed anatomical plates and patient-specific implants versus conventional plates.

CONCLUSIONS

This systematic review showed a significant mean difference in surgery time favouring the use of preformed anatomical plates and patient-specific implants for orbital, upper, and lower limb extremity fractures. Additionally, preformed anatomical plates and patient-specific implants in the lower limb group result in a significantly higher rate of anatomical reduction versus conventional flat plates.

Patient-specific miniplates versus patient-specific reconstruction plate: A biomechanical comparison with 3D-printed plates in mandibular reconstruction

BACKGROUND

Patient-specific 3D-printed miniplates for free flap fixation in mandibular reconstruction were recently associated with enhanced osseous union. Higher mechanical strains resulting from these plates are discussed as reasons, but biomechanical studies are missing. This study aims to examine, whether patient-specific 3D-printed miniplates provide an increased interosteotomy movement (IOM) and lower stiffness compared with reconstruction plates.

METHODS

Polyurethane (PU) mandible and fibula models (Synbone AG, Malans, Schweiz) were used to simulate mandibular reconstruction with a one segment fibula flap equivalent. Osteosynthesis was performed using either four patient-specific 3D-printed miniplates (3D-Mini) or one patient-specific 3D-printed reconstruction plate (3D-Recon). Mastication was simulated using cyclic dynamic loading with increasing loads until material failure or a maximum load of 1000 N. Continuous IOM recording was carried out using a 3D optical tracking system (ARAMIS, Carl Zeiss GOM Metrology, Braunschweig, Germany).

FINDINGS

The averaged stiffness at a load of 100-300 N load did not differ between the groups (p = 0.296). There was a faster 1.0 mm vertical displacement in the 3D-Mini group (26 376 ± 14 190 cycles versus 44 817 ± 30 430 cycles, p = 0.018). The IOM were higher with miniplate fixation in the distal gap (p = 0.040). In the mesial gap, there was no significant difference between the groups (p = 0.160).

INTERPRETATION

Fixation with patient-specific 3D-printed miniplates results in higher mechanical strains. Lower rates of pseudarthrosis, as seen in clinical studies, might be caused by this phenomenon. Surgeons should evaluate the primary use of 3D-printed miniplates in mandibular reconstruction due to advantages of intraoral plate removal alongside safe osteosynthesis.

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

Objectives

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

Methods

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

Results

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

Conclusions

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

Evaluation of the Properties of 3D-Printed Ti Alloy Plates: In Vivo and In Vitro Comparative Experimental Study

Titanium (Ti)-based implants play a significant role in rigid internal fixation in maxillofacial surgery. No study has reported that three-dimensional-printed Ti alloy plates (3D-Ti plates) have comprehensively excellent properties similar to standard plates (Matrix-MANDIBLE, SYNTHES, Switzerland) (Synthes-Ti plates). In this work, we manufactured 3D-Ti plates by selective laser melting with Ti6Al4V powder. The surface morphology, mechanical properties, and bone-plate contact rate of the 3D-Ti plates and the Synthes-Ti plates were characterized and compared via electron microscopy, atomic force microscopy, Vickers hardness test, three-point bending test, and software calculation. Human bone marrow stromal cells (HBMSCs) were cultured on the plates to test their biocompatibility. Importantly, the 3D-Ti plates were placed into a mandibular fracture model to assess the effect of medical application for 4 and 24 weeks. The 3D-Ti plates were demonstrated to have similar biocompatibility and stability for rigid internal fixation with the Synthes-Ti plates, lower roughness (106.44 ± 78.35 nm), better mechanical strength (370.78 ± 1.25 HV10), and a higher bone-plate contact rate (96.9%). These promising results indicate the feasibility of using 3D-Ti plates for irregular shapes and complex anatomical structures in a clinical context.

The Amsterdam UMC protocol for computer-assisted mandibular and maxillary reconstruction; A cadaveric study

OBJECTIVES

In this cadaveric study, the accuracy of CAS guided mandibular and maxillary reconstruction including immediate dental implant placement in different Brown defect classes is assessed.

MATERIALS AND METHODS

The virtual planning and surgical procedure was conducted according to a newly proposed Amsterdam UMC reconstruction protocol. Postoperative evaluation was performed according to a previously proposed evaluation guideline.

RESULTS

Fourteen mandibular and 6 maxillary reconstructions were performed. Average mandibular angle deviations were 1.52°±1.32, 1.85°±1.58, 1.37°±1.09, 1.78°±1.37, 2.43°±1.52 and 2.83°±2.37, respectively for the left and right axial angles, left and right coronal angles and left and right sagittal angles. A total of 62 dental implants were placed in neomandibles with an average dXYZ values of 3.68 ± 2.21 mm and 16 in neomaxillas with an average dXYZ values of 3.24 ± 1.7 mm.

CONCLUSION

Promising levels of accuracy were achieved for all mandibular angles. Dental implant positions approached the preoperative preferred positions well, within the margin to manufacture prosthetic devices.

Current Trends in the Reconstruction and Rehabilitation of Jaw following Ablative Surgery

Simple Summary

The Maxilla and mandible provide skeletal support for of the middle and lower third of our faces, allowing for the normal functioning of breathing, chewing, swallowing, and speech. The ablative surgery of jaws in the past often led to serious disfigurement and disruption in form and function. However, with recent strides made in computer-assisted surgery and patient-specific implants, the individual functional reconstruction of the jaw is evolving rapidly and the prompt rehabilitation of both the masticatory function and aesthetics after jaw resection has been made possible. In the present review, the recent advancements in jaw reconstruction technology and future perspectives will be discussed.

Abstract

The reconstruction and rehabilitation of jaws following ablative surgery have been transformed in recent years by the development of computer-assisted surgery and virtual surgical planning. In this narrative literature review, we aim to discuss the current state-of-the-art jaw reconstruction, and to preview the potential future developments. The application of patient-specific implants and the “jaw-in-a-day technique” have made the fast restoration of jaws’ function and aesthetics possible. The improved efficiency of primary reconstructive surgery allows for the rehabilitation of neurosensory function following ablative surgery. Currently, a great deal of research has been conducted on augmented/mixed reality, artificial intelligence, virtual surgical planning for soft tissue reconstruction, and the rehabilitation of the stomatognathic system. This will lead to an even more exciting future for the functional reconstruction and rehabilitation of the jaw following ablative surgery.

Osseous Union after Mandible Reconstruction with Fibula Free Flap Using Manually Bent Plates vs. Patient-Specific Implants: A Retrospective Analysis of 89 Patients

The aim of this monocentric, retrospective clinical study was to evaluate the status of osseous union in uni- and poly-segmental mandible reconstructions regarding conventional angle-stable manually bent osteosynthesis plates (Unilock 2.0 mm) versus titan laser-melted PSI patient-specific implant’s (PSI). The clinical impact of PSI’s high stiffness fixation methods on bone healing and regeneration is still not well addressed. The special interest was in evaluating the ossification of junctions between mandible and fibula and between osteotomized fibula free flap (FFF) segments. Panoramic radiograph (OPT), computed tomography (CT) scans, or cone-beam CTs (CBCT) of patients who underwent successful FFF for mandible reconstruction from January 2005 to December 2020 were analyzed. A total number of 89 cases (28 females (31.5%), 61 males (68.5%), mean age 58.2 ± 11.3 years, range: 22.8–82.7 years) fulfilled the chosen inclusion criteria for analysis (conventional: n = 44 vs. PSI: n = 45). The present study found an overall incomplete ossification (IOU) rate of 24.7% (conventional: 13.6% vs. PSI: 35.6%; p = 0.017) for mandible to fibula and intersegmental junctions. Between osteotomized FFF segments, an IOU rate of 16% was found in the PSI-group, while no IOU was recorded in the conventional group (p = 0.015). Significant differences were registered for IOU rates in poly-segmental (p = 0.041), and lateral (p = 0.016) mandibular reconstructions when PSI was used. Multivariate logistic regression analysis identified plate exposure and type of plate used as independent risk factors for IOU. Previous or adjuvant radiotherapy did not impact incomplete osseous union in the evaluated study sample. PSI is more rigid than bent mini-plates and shields functional mechanical stimuli, and is the main reason for increasing the rate of incomplete ossification. To enhance the functional stimulus for ossification it has to be discussed if patient-specific implants can be designed to be thinner, and should be divided into segmental plates. This directs chewing forces through the bone and improves physiological bone remodeling.

Craniofacial Reconstruction with Personalized Lightweight Scaffold Fabricated Using Electron-Beam Additive Manufacturing

Implants are the most popular option for restoring the facial anatomy in the event of a mishap. The commercially available craniofacial implants are of standard shapes, which need to be tailored and shaped to accurately fit the patient’s anatomy. The manual shaping of the implant to match the bone contours is conducted during surgical operation, and is a cumbersome and inaccurate process. Recent breakthroughs in computer-aided design, analysis, and additive manufacturing (AM) have allowed the precise and rapid manufacture of bespoke scaffolds for difficult anatomical restoration. The goal of this research is to investigate the use of scaffolds for craniofacial reconstruction and their fabrication using electron-beam additive manufacturing (EBAM). Personalized cheekbone scaffolds are additively fabricated using Ti6Al4V and subjected to compression testing. Finally, the scaffold design with the highest compressive strength is subjected to biomechanical analysis. The biomechanical analysis results indicate that the maximum Von Mises stress (40 MPa) and equivalent strain (0.4 µm) are significantly low in magnitude, thus providing a desirable implant that is both flexible and stable. The custom-designed cheekbone scaffold manufactured with AM technology not only aids in bone-implant ingrowth but also helps in reducing implant weight and ensuring implant stability and long-term effectiveness.

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

Background

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

Methods

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

Results

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

Conclusions

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

Patient-Specific 3D-Printed Miniplates for Free Flap Fixation at the Mandible: A Feasibility Study

Background

This study was conducted to evaluate the feasibility, clinical outcomes, and accuracy of patient-specific 3D-printed miniplates for mandible reconstruction with fibula free flaps.

Methods

A feasibility study was conducted with 8 patients. Following virtual planning, patient-specific 1.0 mm titanium non-locking miniplates were produced via laser selective melting. 3D-printed cutting and drilling guides were used for segmental mandible resection and flap harvesting. Flap fixation was performed with two 4-hole miniplates and 2.0 mm non-locking screws (screw length 7 mm) for each intersegmental gap. Clinical follow-up was at least 6 months. Preoperative and postoperative CT/cone beam CT data were used for 3D accuracy analysis and evaluation of bone healing. Plate-related complications were monitored clinically.

Results

Patient-specific miniplate fixation of all flaps was successfully conducted (4 mono-segmental, 4 dual-segmental) with high accuracy (3.64 ± 1.18 mm) between the virtual plan and postoperative result. No technical complications were encountered intraoperatively. Osseous union occurred in all intersegmental gaps (1 partial, 18 complete) after 10 ± 2 months. No material fracture, dislocation, or plate exposure was observed.

Conclusions

Based on this pilot observational study including a limited number of patients, free flap fixation for mandibular reconstruction with patient-specific 3D-printed miniplates is feasible and associated with high accuracy, bone healing, and remote soft tissue complications.

A Comprehensive Approach for Measuring Spatial Deviations of Computer-Assisted Mandibular Reconstruction

BACKGROUND

Computer-assisted surgery has become the mainstream in mandibular reconstruction, but the lack of a standard measuring approach for spatial deviations of mandible hinders postoperative verification and the comparison of different subjects. This study aims to set up a comprehensive approach for measuring spatial deviations of computer-assisted mandibular reconstruction.

METHODS

A systematic review was conducted to extract all measurements for computer-assisted mandibular reconstruction. Thereafter, eligible measurements were included in the authors' comprehensive approach, which categorized the measurements according to different anatomical structures and landmarks.

RESULTS

A total of 80 studies were included in the authors' systematic review, and 31 measurements were extracted. The authors established a comprehensive panel of anatomical landmarks to facilitate measurement, including parts, points, lines, planes, and angles. These measurements encompassed spatial deviations of the overall mandible, condyle, gonial angle, bone grafts, midline, surgical plate, osteotomy, and miscellaneous indicators. A calculation spreadsheet was developed to collect landmarks and compute deviations automatically with built-in formulas. Finally, a simplified panel of measurements was recommended for spatial deviations of mandibular reconstruction.

CONCLUSIONS

A comprehensive approach for measuring spatial deviations of computer-assisted mandibular reconstruction was established. Future studies will confirm this approach as an effective and scientific system for postoperative verification of computer-assisted mandibular reconstruction.

A Comparative Study on a Novel Fibula Malleolus Cap to Increase the Accuracy of Oncologic Jaw Reconstruction

OBJECTIVES

Although computer-assisted surgery using fibula flap has been widely applied for oncologic jaw reconstruction in recent years, the inaccurate positioning of the fibula harvest guide brings sliding and rotational errors, which leads to compromised accuracy in simultaneous implant placement and dental rehabilitation. This study aimed to develop a novel three-dimensional (3D)-printed patient-specific fibula malleolus cap to increase oncologic reconstruction accuracy.

METHODS

In this prospective comparative study with a recent historical control cohort, patients in need of oncologic jaw reconstruction with fibula free flaps were recruited. In the study group, the fibula was harvested with the guide of the malleolus cap, whereas in the control group, without the malleolus cap. Deviations of location and angulation of distal fibula osteotomies, jaw reconstruction segments, and simultaneous dental implants were compared.

RESULTS

Twenty patients were recruited, with 10 in each arm. The application of the malleolus cap significantly reduced the deviations in locations and angles of distal fibula osteotomies, from 9.5 to 4.1 mm and 25.3° to 8.7°. For the simultaneous dental implants placed in the fibula flaps, there was a significant increase in the accuracy of implant platform locations (the average deviation from 3.2 to 1.3 mm), apex locations (from 3.8 to 1.5 mm), and angles (from 11.3° to 4.6°). No significant difference was detected in the accuracy of fibula reconstruction segments.

CONCLUSIONS

We developed a novel fibula malleolus cap to overcome the sliding and rotational errors during fibula flap harvesting for oncologic jaw reconstruction, with increased accuracy in simultaneous dental implants. This is a step forward to achieve a satisfactory functional outcome of jaw reconstruction with dental rehabilitation.

Clinical application of 3D-printed patient-specific guide plate combined with computer navigation in acetabular reconstruction following resection of periacetabular tumors

Background

The precise acetabular reconstruction has historically been a challenging procedure. 3D-printed patient-specific guide (PSG) and computer navigation (CN) technologies have been used to assist acetabular component positioning and pelvic reconstruction. This precise reconstruction approach may translate into clinical benefit.

Methods

The clinical data of 84 patients who underwent periacetabular malignant tumor resection and screw-rod-acetabular cage system reconstruction in our center from January 2013 to December 2020 were retrospectively analyzed. Patients were divided into four groups: free hand (FH) group, PSG group, CN group, and PSG combined with computer navigation (PSG + CN) group. The operation time, intraoperative blood loss, and number of fluoroscopy views were recorded. The oncological prognosis, radiographic measurements of the acetabulum, limb function data, and postoperative complications were compared among groups. And finally, we evaluated the risk factors for mechanical failure of the prosthesis.

Results

The postoperative X-ray and computed tomography (CT) scan revealed that the vertical offset discrepancy (VOD) between affected side and contralateral side was 8.4±1.9, 5.9±2.2, 4.1±1.3, and 2.4±1.2 mm in each groups; the horizontal offset discrepancy (HOD) was 9.0±1.9, 6.1±2.2, 3.2±1.3, and 2.1±1.2 mm, correspondingly; the abduction angle discrepancy (ABAD) was 8.6°±1.8°, 5.6°±2.0°, 2.5°±1.3°, and 1.8°±0.9°, respectively; the anteversion angle discrepancy (ANAD) was 5.9°±1.6°, 3.6°±1.7°, 2.9°±1.6°, and 1.9°±0.9°, correspondingly. Statistical results show that the PSG + CN group was superior to the FH group and the PSG group in terms of acetabular position and limb function (P<0.05). Body mass index (P=0.040) and resection type (P=0.042) were found to be the high-risk factors for mechanical failure of the prosthesis.

Conclusions

PSG + CN has potential advantages in improving the accuracy and safety of acetabular positioning and reconstruction.

Deviation Analyses of Computer-Assisted, Template-Guided Mandibular Reconstruction With Combined Osteotomy and Reconstruction Pre-Shaped Plate Position Technology: A Comparative Study

Background

Computer-assisted and template-guided mandibular reconstruction provides higher accuracy and less variation than conventional freehand surgeries. The combined osteotomy and reconstruction pre-shaped plate position (CORPPP) technique is a reliable choice for mandibular reconstruction. This study aimed to evaluate the accuracy of CORPPP-guided fibular flap mandibular reconstruction and analyze the possible causes of the deviations.

Patients and Methods

From June 2015 to December 2016, 28 patients underwent fibular flap mandibular reconstruction. Virtual planning and personalized CORPPP-guided templates were applied in 15 patients while 13 patients received conventional freehand surgeries. Deviations during mandibulectomy and fibular osteotomy, and overall and triaxial deviation of the corresponding mandibular anatomical landmarks were measured by superimposing the pre- and postoperative virtual models.

Results

The deviation of the resection line and resection angle was 1.23 ± 0.98 mm and 4.11° ± 2.60°. The actual length of fibula segments was longer than the designed length in 7 cases (mean: 0.35 ± 0.32 mm) and shorter in 22 cases (mean: 1.53 ± 1.19 mm). In patients without ramus reconstruction, deviations of the ipsilateral condylar head point (Co.), gonion point (Go.), and coracoid process point (Cor.) were 6.71 ± 3.42 mm, 5.38 ± 1.71 mm, and 11.05 ± 3.24 mm in the freehand group and 1.73 ± 1.13 mm, 1.86 ± 0.96 mm, and 2.54 ± 0.50 mm in the CORPPP group, respectively, with significant statistical differences (p < 0.05). In patients with ramus reconstruction, deviations of ipsilateral Co. and Go. were 9.79 ± 4.74 mm vs. 3.57 ± 1.62 mm (p < 0.05), and 15.17 ± 6.53 mm vs. 4.36 ± 1.68 mm (p < 0.05) in the freehand group and CORPPP group, respectively.

Conclusion

Mandibular reconstructions employing virtual planning and personalized CORPPP-guided templates show significantly higher predictability, convenience, and accuracy of mandibular reconstruction compared with conventional freehand surgeries. However, more clinical cases were required for further dimensional deviation analysis. The application and exploration of clinical practice would also continuously improve the design of templates.

The Learning Curve of Computer-Assisted Free Flap Jaw Reconstruction Surgery Using 3D-Printed Patient-Specific Plates: A Cumulative Sum Analysis

Background

Computer-assisted jaw reconstruction (CAJR) has benefits in reducing operation time and improving reconstruction accuracy, compared to conventional freehand jaw reconstruction. However, no information is available regarding learning curves in CAJR with the use of 3D-printed patient-specific surgical plates (PSSP). The purpose of this study was to assess surgical outcomes and learning curve for the first 58 consecutive CAJR using 3D-printed PSSP performed by a single surgical team in a single institution.

Methods

In a prospective study, consecutive patients who underwent free flap CAJR using 3D-printed PSSP were included. The determination of proficiency, based on the cumulative sum of surgical success (no major adjustment of 3D-printed PSSP, flap survival) passing the acceptable boundary line of cumulative sum analysis, was the primary outcome. To find out any potential factors influencing the learning curve, baseline characteristics of patients were compared before and after proficiency achievement. Secondary outcomes included inflexion points of the total operation time, blood loss, length of hospital stay, and bone graft deviation, measured by the cumulative sum analysis.

Results

From December 2016 to November 2020, 58 consecutive cases underwent surgery performed by a single surgical team. The overall surgical success rate was 94.8% (55/58). A three-stage learning curve of primary outcome was observed. The proficiency was achieved after 23 cases. The proportions of advanced tumor staging and concomitant surgery after obtaining proficiency were significantly higher than those before achieving proficiency (p = 0.046 and p < 0.001, respectively). Mean values of operation time, intraoperative blood loss, length of hospital stay, and bone graft deviation were 532.5 ± 119.2 min, 1,006.8 ± 547.2 ml, 16.1 ± 6.3 days, and 0.9 ± 1.2 mm, respectively. Two trends of learning curve were observed in the CUSUM analyses of total operation time, length of hospital stay, and bone graft deviation, in which the first and second inflexion points occurred between 8 and 17 cases and between 43 and 46 cases, respectively.

Conclusion

Our results revealed a three-stage learning curve of CAJR with the use of PSSP, including initial learning, plateau, and overlearning. Based on CUSUM analysis, the surgical proficiency was achieved after 23 cases, and total operation time, length of hospital stay, and bone graft deviation stabilized after 8–17 cases.

Adherence to Computer-Assisted Surgical Planning in 136 Maxillofacial Reconstructions

Objective

To investigate the adherence to initially planned maxillofacial reconstructions using computer-assisted surgery (CAS) and to identify the influential factors affecting its compliance for maxillofacial reconstruction.

Patients and Methods

A retrospective analysis of 136 computer-assisted maxillofacial reconstructive surgeries was conducted from January 2014 to June 2020. The categorical parameters involved age, gender, disease etiology, disease site, defect size, bone flap segments, and flap type. Apart from descriptive data reporting, categorical data were related by applying the Fisher-exact test, and a p-value below 5% was considered statistically significant (P < 0.05).

Results

The main reasons for partial or non-adherence included unfitness, patient health condition, and other subjective reasons. Out of the total patient population, 118 patients who underwent mandibular reconstruction showed higher CAS compliance (83.9%) compared to the 18 midface reconstruction (72.2%) without any statistically significant difference (p = 0.361). Based on the size of the defect, a significantly higher CAS compliance (p = 0.031) was observed with a minor defect (80.6%) compared to the large-sized ones (74.1%). The bone flaps with two or more segments were significantly (p = 0.003) prone to observe a partial (15.4%) or complete (12.8%) discard of the planned CAS compared to the bone flaps with less than two segments. The malignant tumors showed the lowest CAS compliance when compared to other disorders without any significant difference (p = 0.1).

Conclusion

The maxillofacial reconstructive surgical procedures offered optimal compliance to the initially planned CAS. However, large-sized defects and multiple bone flap segments demonstrated a higher risk of partial or complete abandonment of the CAS.

Three-dimensional Printing Technology for Deep Circumflex Iliac Artery Flap: From Recipient to Donor Sites

The deep circumflex iliac artery (DCIA) flap is one of the most commonly used vascularized free flaps for jaw reconstruction; however, its clinical application is limited by donor site complications. We aimed to describe a new technique of using 3-dimensionally (3D) printed patient-specific devices for mandibular reconstruction with DCIA flap and simultaneous dental implants, and for donor site restoration after harvesting the DCIA flap. One patient with mandible ameloblastoma underwent mandibular reconstruction using a DCIA flap with the “jaw-in-a-day” approach. The 3D-printed patient-specific devices included mandibular cutting guides, DCIA harvesting and dental implant guide, surgical plate, and iliac prosthesis. The postoperative 1-month accuracy measurement showed the mean distance deviations of the mandible, transferred bone grafts, dental implants and iliac prosthesis were 1.8 mm, 2.1 mm, 0.9 mm, and 1.2 mm, respectively. Three-dimensionally printed iliac prosthesis satisfactorily restored the contour of the iliac crest after DCIA flap harvesting. No complication of donor site was recorded during the follow-up of 12 months. We successfully used 3D-printed patient-specific implants in both donor and recipient sites for DCIA flap jaw reconstruction. Further studies with a larger sample size and long-term follow-up are needed.

Artificial intelligence-enabled automatic segmentation of skull CT facilitates computer-assisted craniomaxillofacial surgery

BACKGROUND

The image segmentation of skull CT is the cornerstone for the computer-assisted craniomaxillofacial surgery in multiple aspects. This study aims to introduce an AI-enabled automatic segmentation and propose its prospect in facilitating the computer-assisted surgery.

METHODS

Three patients enrolled in a clinical trial of computer-assisted craniomaxillofacial surgery were randomly selected for this study. The preoperative helical CT scans of the head and neck region were subjected to the AI-enabled automatic segmentation in Mimics Viewer. The performance of AI segmentation was evaluated based on the requirements of computer-assisted surgery.

RESULTS

All three patients were successfully segmented by the AI-enabled automatic segmentation. The performance of AI segmentation was excellent regarding key anatomical structures. The overall quality of bone surface was satisfying. The median DICE coefficient was 92.4% for the maxilla, and 94.9% for the mandible, which fulfilled the requirements of computer-assisted craniomaxillofacial surgery.

CONCLUSIONS

The AI-enabled automatic segmentation could facilitate the preoperative virtual planning and postoperative outcome verification, which formed a feedback loop to enhance the current workflow of computer-assisted surgery. More studies are warranted to confirm the robustness of AI segmentation with more cases.

Spatial deviations of the temporomandibular joint after oncological mandibular reconstruction

Spatial deviations of the temporomandibular joint (TMJ) after oncological mandibular reconstruction are important to the aesthetic and functional rehabilitation. The aim of this study was to clarify whether and how three dimensionally (3D) printed patient-specific surgical plates, and the preservation of the condyle or ramus, affect spatial deviations of the TMJ. A total of 33 patients who underwent mandibular reconstruction via computer-assisted surgery were included. Regarding absolute deviations, patients in the 3D-printed plate group showed smaller TMJ deviations compared to those in the conventional plate group. There was no difference in absolute deviations of the TMJ regardless of whether the condyle or ramus was preserved. Regarding physiological deviations, the impact on the contralateral TMJ was smaller in the 3D-printed plate group. Patients with both the condyle and ramus removed had significantly higher deviations of the condyle and joint space. In summary, 3D-printed patient-specific surgical plates improved the spatial accuracy of the TMJ. Under physiological conditions, TMJ deviations on the operated side were mainly affected by the preservation of the condyle. Removal of both the condyle and ramus caused more severe spatial interference to the TMJ; this should be further confirmed.

Bioengineering for head and neck reconstruction: the role of customized flaps

PURPOSE OF REVIEW

The purpose of this review is to provide the reader with an overview of the present and future applications of bioengineering for head and neck reconstruction, ranging from the application of Computed Assisted Surgery (CAS) to the most recent advances in 3D printing and tissue engineering.

RECENT FINDINGS

The use of CAS in head and neck reconstruction has been demonstrated to provide shorter surgical times, improved reconstructive accuracy of bone reconstruction, and achieves better alignment of bone segments in osteotomized reconstructions. Beyond its classical application in bone reconstructions, CAS has demonstrated reliability in the planning and harvesting of soft tissue flaps. To date, literature regarding bioengineering for head and neck reconstruction is mainly focused on in-vitro and animal model experiments; however, some pioneering reports on human patients suggest the potential feasibility of this technology.

SUMMARY

Bioengineering is anticipated to play a key role in the future development of customized flaps for head and neck reconstruction. These technologies are particularly appealing as a new technology to address certain unsolved challenges in head and neck reconstruction.