Mandible reconstruction using patient-specific pre-bent reconstruction plates: comparison of standard and transfer key methods

Bone reconstruction using CAD/CAM technology in head and neck surgical oncology. A narrative review of state of the art and aesthetic-functional outcomes

Bone defects following resections for head and neck tumours can cause significant functional and aesthetic defects. The choice of the optimal reconstructive method depends on several factors such as the size of the defect, location of the tumour, patient’s health and surgeon’s experience. The reconstructive gold standard is today represented by revascularised osteo-myocutaneous or osteomuscular flaps with osteosynthesis using titanium plates. Commonly used donor sites are the fibula, iliac crest, and lateral scapula/scapular angle. In recent years, computer-aided design (CAD)/computer assisted manufacturing (CAM) systems have revolutionised the reconstructive field, with the introduction of stereolithographic models, followed by virtual planning software and 3D printing of plates and prostheses. This technology has demonstrated excellent reliability in terms of accuracy, precision and predictability, leading to better operative outcomes, reduced surgical times and decreased complication rates. Among the disadvantages are high costs, implementation times and poor planning adaptability. These problems are finding a partial solution in the development of “in house” laboratories for planning and 3D printing. Strong indications for the use of CAD/CAM technologies today are the reconstruction of total or subtotal mandibular or maxillary defects and secondary bone reconstructions.

Finite element analysis and clinical application of 3D-printed Ti alloy implant for the reconstruction of mandibular defects

BACKGROUND

The reconstruction of segmental defect of the mandible has always been a challenge. The customized reconstruction plate without a bone graft is also considered a transitional means of rehabilitation and reconstruction in some cases.

METHODS

This study evaluated the biomechanical behaviors of customized plates with different structural designs comparing with commercial plates using the finite element method in reconstrution of the lateral mandible defect.

RESULTS

Simulations revealed the stress state in the plate bodies, bone tissues and screws were associated with the width, height, thickness of the plates as well as the distribution of screws. In all of the groups, the system of 16 mm-high, 2.8 mm-thick customized reconstruction plate with 10 screws was considered to be the most ideal design because of the most harmonious biomechanical state. What's more, the stress shielding effects were not obvious in this experiment. Based on the above findings, we conducted a clinical case analysis to verify the mechanical properties of customized reconstruction and obtained a satisfactory operation result.

CONCLUSIONS

The results show that by adjusting the contour parameters of the reconstruction plates, an ideal and reliable customized plate can be manufactured. And the customized 3D-printed Ti alloy implant will be a new way to achieve mandibular reconstruction in patients unable to perform autologous bone graft surgery.

TRIAL REGISTRATION

The present trial has been registered with ChiCTR, the registration number is ChiCTR 2,000,038,973 on 11/10/2020.

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.

The value of prebent reconstruction plates and in-house 3D printing

INTRODUCTION

Reconstruction plates, prebent on 3D printed models, are a cheap, quick, and safe solution to improve mandibular reconstruction procedures. The European Medical Device Regulation has changed recently and severely affects 3D printing in hospitals. Therefore, its legitimation must be discussed. This retrospective observational Case-Control Study aimed to evaluate the impact of prebent reconstruction plates on the condylar position in the temporomandibular joint after continuity resection of the mandible in oncological cases.

MATERIALS AND METHODS

We included patients who underwent segmental mandibular resection without exarticulation of the condyle or history of prior surgery. The patients were divided into groups with prebent plates on a stereolithographic model and intraoperatively bent reconstruction plates. The segmental defects were categorized using the Jewer Classification. Computed Tomography (CT) scans before and after surgery were analyzed using a standardized method to measure the metric movement of the condyles, as well as their angulation to reference planes to quantify positional changes (primary outcome measures). The influence of the defect location, according to the Jewer classification, was evaluated as a secondary outcome measure.

RESULTS

73 patients, including 33 with preformed reconstruction plates, were included. We could show significantly fewer rotational deviations in cases of prefabricated osteosynthesis in the coronal plane (p<0,001) and in the sagittal plane (p<0,027).

DISCUSSION

Using preformed reconstruction plates on 3D printed models improves the correct anatomical position of the condyle after mandibular resection. Especially Jewer-class-L defects seem to benefit from individualized reconstruction plates.

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.

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.

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

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

Impact of Periosteal Branches and Septo-Cutaneous Perforators on Free Fibula Flap Outcome: A Retrospective Analysis of Computed Tomography Angiography Scans in Virtual Surgical Planning

BACKGROUND

Virtual surgical planning (VSP) for jaw reconstruction with free fibula flap (FFF) became a routine procedure and requires computed tomography angiography (CTA) for preoperative evaluation of the lower limbs vascular system and the bone. The aim of the study was to assess whether the distribution and density of periosteal branches (PB) and septo-cutaneous perforators (SCP) of the fibular artery have an impact on flap success.

METHOD

This retrospective clinical study assessed preoperative CTA of the infra-popliteal vasculature and the small vessel system of 72 patients who underwent FFF surgery. Surgical outcome of flap transfer includes wound healing, subtotal, and total flap loss were matched with the segmental vascular supply.

RESULT

A total of 72 patients (28 females, 38.9 %; 44 males, 61.1 %) fulfilled the study inclusion criteria. The mean age was 58.5 (± 15.3 years). Stenoses of the lower limbs' vessel (n = 14) were mostly detected in the fibular artery (n = 11). Flap success was recorded in n = 59 (82.0%), partial flap failure in n = 4 (5.5%) and total flap loss in n = 9 (12.5%). The study found a mean number (± SD) of 2.53 ± 1.60 PBs and 1.39 ± 1.03 SCPs of the FA at the donor-site. The proximal FFF segment of poly-segmental jaw reconstruction showed a higher rate of PB per flap segment than in the distal segments. Based on the total number of prepared segments (n = 121), 46.7% (n = 7) of mono-, 40.4% (n = 21) of bi-, and 31.5 % (n = 17) of tri-segmental fibula flaps were at least supplied by one PB in the success group. Overall, this corresponds to 37.2% (45 out of 121) of all successful FFF. For total flap loss (n = 14), a relative number of 42.9% (n = 6) of distinct supplied segments was recorded. Wound healing disorder of the donor site was not statistically significant influenced by the detected rate of SCP.

CONCLUSION

In general, a correlation between higher rates of PB and SCP and the flap success could not be statistically proved by the study sample. We conclude, that preoperative PB and SCP mapping based on routine CTA imaging is not suitable for prediction of flap outcome.

Soft Tissue Dehiscence Associated with a Titanium Patient-Specific Implant: A Prosthetic Solution as an Alternative to Soft Tissue Grafting

Patients. This clinical report describes the detailed prosthodontic management of a 23-year-old male patient suffering from soft tissue complication following the placement of a 3d-printed titanium patient-specific implant. This implant was implemented simultaneously with the resection of a calcifying cystic odontogenic tumor related to the maxillary arch. Later, soft tissue dehiscence and implant exposure were encountered with subsequent food impaction, infection, and pus discharge. The treatment plan was to fabricate removable partial denture. The prosthesis was planned to be retained by bar and clip attachment on the patient-specific implant side, while on the other side, the removable prosthesis was allowed to engage two abutments with an embrasure clasp assembly in addition to covering the palatal tissues to offer protection for the soft tissue dehiscence against food impaction. Discussion. Soft tissue dehiscence and implant exposure are among the frequently reported complications associated with the patient-specific implant. The resulting infection complicates the prognosis of the implemented implant and necessitates, in some occasions, its removal. The selection of the removable prosthesis to cover soft tissue dehiscence was a conservative alternative to the implant removal as it protects the exposed titanium surface from food impaction while maintaining the implant functionality. Conclusion. Three-year follow-up showed complete resolution of the patient's complaints while fulfilling the patient's aesthetic and functional demands and indicates that the use of detachable overlay prosthesis could be one of the proposed treatment options.

Virtual reconstruction of orbital floor defects using a statistical shape model

PURPOSE

The current standard in reconstructing defects of the orbital floor, by using the concept of mirroring, is time-consuming and ignores the natural asymmetry of the skull. By using a statistical shape model (SSM), the reconstruction can be automatized and improved in accuracy. The present study aims to show the possibilities of the virtual reconstruction of artificial defects of the orbital floor using an SSM and its potentials for clinical implementation.

METHODS

Based on 131 unaffected CT scans of the midface, an SSM was created which contained the shape variability of the orbital floor. Nineteen midface CT scans, that were not included in the SSM, were manually segmented to establish ground truth (control group). Then artificial defects of larger and smaller sizes were created and reconstructed using SSM (Group I) and the gold standard of mirroring (Group II). Eventually, a comparison to the surface of the manual segmentation (control group) was performed.

RESULTS

The proposed method of reconstruction using an SSM leads to more precise reconstruction results, compared with the conventional method of mirroring. Whereas mirroring led to the reconstruction errors of 0.7 mm for small defects and 0.73 mm for large defects, reconstruction using SSM led to deviations of 0.26 mm (small defect) and, respectively, 0.34 mm (large defect).

CONCLUSIONS

The presented approach is an effective and accurate method for reconstructing the orbital floor. In connection with modern computer-aided design and manufacturing, individual patient-specific implants could be produced according to SSM-based reconstructions and could replace current methods using manual bending techniques. By acknowledging the natural asymmetry of the human skull, the SSM-based approach achieves higher accuracy in reconstructing injured orbits.

Computed Tomography Angiography (CTA) before Reconstructive Jaw Surgery Using Fibula Free Flap: Retrospective Analysis of Vascular Architecture

Computed tomography angiography (CTA) is widely used in preoperative evaluation of the lower limbs' vascular system for virtual surgical planning (VSP) of fibula free flap (FFF) for jaw reconstruction. The present retrospective clinical study analysed n = 72 computed tomography angiographies (CTA) of lower limbs for virtual surgical planning (VSP) for jaw reconstruction. The purpose of the investigation was to evaluate the morphology of the fibular bone and its vascular supply in CTA imaging, and further, the amount and distribution of periosteal branches (PB) and septo-cutaneous perforators (SCPs) of the fibular artery. A total of 144 lower limbs was assessed (mean age: 58.5 ± 15.3 years; 28 females, 38.9%; 44 males, 61.1%). The vascular system was categorized as regular (type I-A to II-C) in 140 cases (97.2%) regarding the classification by Kim. Absent anterior tibial artery (type III-A, n = 2) and posterior tibial artery (type III-B, n = 2) were detected in the left leg. Stenoses were observed mostly in the fibular artery (n = 11), once in the anterior tibial artery, and twice in the posterior tibial artery. In total, n = 361 periosteal branches (PBs) and n = 231 septo-cutaneous perforators (SCPs) were recorded. While a distribution pattern for PBs was separated into two clusters, a more tripartite distribution pattern for SCPs was found. We conclude that conventional CTA for VSP of free fibula flap (FFF) is capable of imaging and distinguishing SCPs and PBs.

Time Reduction by Prebending Osteosynthesis Plates Using 3D-Printed Anatomical Models, In Patients Treated With Open Reduction and Internal Fixation

INTRODUCTION

The incidence of facial bones fractures is 18 to 32 for each 100,000 inhabitants. The most affected population are young working people. Fractures are most commonly caused by assaults and motor vehicle accidents. Its cost of care reaches 1.06 billion dollars. Premodeling osteosynthesis plates with anatomical models can decrease surgical time, bleeding, and increase patient satisfaction. This study aims to evaluate the impact of premodeled osteosynthesis plates, using anatomical models in patients with facial fractures.

MATERIAL AND METHODS

Patients with facial fractures treated by open reduction and internal fixation were included-Group A without premolding plates and Group B with premolding. The variables studied were: age, sex, etiology of the fractures, number of fractures, among other variables that reflect the quality of the results.

RESULTS

A total of 17 osteosynthesis plates were included in 6 patients. The age was 22 to 47 years; all patients were male. The maximum surgery time was 129 to 300 minutes. The average time to start work was 4.8 weeks. When comparing the variables between the groups, we found no difference between the groups for bleeding P = 0.24, the start of work P = 0.19, the time of surgery P = 0.082, or for osteosynthesis time P = 0.15. There was only a significant difference in patient satisfaction, P = 0.04.

CONCLUSIONS

The evidence collected shows that premodeling the plates only improves patients' satisfaction among facial fractures treated by open reduction and internal fixation.

Heterotopic Ossification of the Vascular Pedicle after Maxillofacial Reconstructive Surgery Using Fibular Free Flap: Introducing New Classification and Retrospective Analysis

Heterotopic ossification (HO) is one of the described phenomena after maxillofacial reconstructive surgery using fibular free flap (FFF) at the reception-site. The aim of this study was to determine the radiological incidence and form of HO along the fibular vascular pedicle as well as the rate of clinical symptoms if present. CT-scans of 102 patients who underwent jaw reconstructive surgery by using FFF from January 2005 to December 2019 were evaluated concerning the presence of HO. Subsequently, the patient files were evaluated to identify the cases with clinical signs and complications related to the presence of HO. A radiological classification of four different HO types was developed. Out of 102 patients, 29 (28.43%) presented radiological findings of HO. Clinical symptoms were recorded in 10 cases (9.8%) (dysphagia (n = 5), trismus (n = 3), bony masses (n = 2)) and from these only five (4.9%) needed surgical removal of calcified structures. HO occurs significantly in younger patients (mean 52.3 year). In maxillary reconstructions, HO was radiologically visible six months earlier than after mandibular reconstruction. Furthermore, HO is observed after every third maxilla and every fourth mandible reconstruction. This study developed for the first time a classification of four distinct HO patterns. HO types 1 and 2 were mostly observed after mandible reconstruction and type 4 predominantly after maxilla reconstruction.

Patient-Specific Mandibular Reconstruction Plates Increase Accuracy and Long-Term Stability in Immediate Alloplastic Reconstruction of Segmental Mandibular Defects

OBJECTIVES

The aim of the current study was to evaluate potential differences in the accuracy of mandibular reconstruction and long-term stability, with respect to different reconstructive procedures.

METHODS

In total, 42 patients who had undergone primary segmental mandibular resection with immediate alloplastic reconstruction, with either manually pre-bent or patient-specific mandibular reconstruction plates (PSMRP), were included in this study. Mandibular dimensions, in terms of six clinically relevant distances (capitulum [most lateral points], capitulum [most medial points], incisura [most caudal points], mandibular foramina, coronoid process [most cranial points], dorsal tip of the mandible closest to the gonion point) determined from tomographic images, were compared prior to, and after surgery.

RESULTS

Dimensional alterations were significantly more often found when conventionally bent titanium reconstruction plates were used. These occurred in the area of the coronoid process (p = 0.014). Plate fractures were significantly (p = 0.022) more often found within the manually pre-bent group than within the PSMRP group (17%/0%).

CONCLUSION

The results suggest that the use of PSMRP may prevent rotation of the proximal mandibular segment, thus avoiding functional impairment. In addition, the use of PSMRP may potentially enhance the long-term stability of alloplastic reconstructions.

Accurate and cost-effective mandibular biomodels: a standardized evaluation of 3D-Printing via fused layer deposition modeling on soluble support structures

INTRODUCTION

Medical biomodels can be used for illustration of medical conditions, preoperative planning or to facilitate pre-bending of osteosynthesis material. They have been shown to be an effective and efficient method to reduce operating time, blood loss and wound stress in cranio-maxillo-facial surgery. Lately, new time and cost-efficient 3D-printing methods have been introduced into the mass-market. The aim of this study was to establish a standardized method of evaluation and consequently evaluate Fused Layer Deposition Modeling in combination with soluble support structures for fabrication of medical biomodels regarding precision and cost-effectiveness.

MATERIALS & METHODS

Twenty-one biomodels of human mandibles equipped with measuring appliances were printed on a FLDM 3D-printers (Ultimaker 3 Extended) using a polyactate filament and a water-soluble Polyvinyl alcohol-based support structures. Precision of these models was compared to commercial, polyamide sintered models and the planning data. Production costs, printing times and post processing procedures were evaluated.

RESULTS

Duration of printing of mandibular biomodels was between 6 h 5 min - 15 h 9 min (mean 9 h 12 min, ±2 h 25 min). The average cost of materials was €5.90 (± €1.28) per model. With an average aberrance of 0.29 mm, FLDM printing delivered a high level of accuracy. It was significantly superior to the polyamide reference models in the area of the semilunar incision, yet inferior at the coronoid process.

CONCLUSION

FLDM printers are able to provide very precise biomodels at very low costs. The use of using soluble support structures reduces time, costs and equipment needed for post processing procedures close to zero.

Sequential application of novel guiding plate system for accurate transoral mandibular reconstruction

OBJECTIVES

The aim of this article is to introduce and share our experience in the sequential use of a novel guiding plate system for accurate mandibular reconstruction via transoral approach and evaluate its clinical effects.

METHODS

Ten patients were operated with transoral mandibulectomy and simultaneous mandibular reconstruction using a novel guiding plate system. Postoperatively, aesthetic assessment and quantitative evaluation were analyzed by measuring the parameters like discrepancy in osteotomy lines, mandibular similarity and symmetry. The independent samples t-test was used and P < 0.05 was considered as significant.

RESULTS

All patients underwent planned transoral surgical procedure successfully. The postoperative aesthetic assessment was rated as excellent. The discrepancy between virtual and actual osteotomy lines, at anterior and posterior regions was 0.80 ± 0.08 and 0.98 ± 0.37 mm, respectively. The postoperative evaluation revealed that mandibular similarity was 0.85 ± 0.03, coronal mandibular angle (CMA) 0.66 ± 0.40, axial mandibular angle (AMA) 1.97 ± 1.25, and sagittal mandibular angle (SMA) 1.97 ± 1.05. There was statistically significant difference in the mean values of osteotomy line discrepancy, mandibular similarity and symmetry, among novel guiding plate and traditional plate groups.

CONCLUSIONS

The novel guiding plate system is a viable and easy-to-use technology for improving the surgical outcomes in patients requiring transoral mandibulectomy and simultaneous mandibular reconstruction by overcoming the problem of limited access due to the presence of lips and cheeks. This can highly improve the precision in osteotomy, fixation of the prebent titanium reconstruction plate, spatial relation transfer, and achieving better symmetry and similarity of mandibular contour.

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

Background

Surgeons are pursuing accurate head and neck reconstruction to enhance aesthetic and functional outcomes after oncologic resection. This study aimed to investigate whether accuracy of head and neck reconstruction is improved with the use of three-dimensionally (3D)-printed patient-specific surgical plates compared with conventional plates.

Methods

In this comparative study, patients were prospectively recruited into the study group (3DJP16) with 3D-printed patient-specific surgical plates. The patients in control group with conventional surgical plates were from a historic cohort in the same unit. The primary end point of the study was the accuracy of head and neck reconstruction. The secondary end points were accuracy of osteotomy, intraoperative blood loss, total operative time, and length of hospital stay.

Results

The study recruited of 33 patients, including 17 in the study group and 16 in the control group. The patients’ baseline characteristics were similar between the two groups. The absolute distance deviation of the maxilla or mandible was 1.5 ± 0.5 mm in the study group and 2.1 ± 0.7 mm in the control group [mean difference, − 0.7 mm; 95% confidence interval (CI) − 1.1 to − 0.3; p = 0.003], showing superior accuracy of reconstruction for the patients with 3D-printed patient-specific surgical plates. Improved accuracy of reconstruction also was detected in terms of bilateral mandibular angles and bone grafts. Concerning the secondary end points, the accuracy of the osteotomy was similar in the two groups. No difference was found regarding intraoperative blood loss, total operative time, or length of hospital stay.

Conclusions

This is the first study to prove that compared with conventional plates, 3D-printed patient-specific surgical plates improve the accuracy of oncologic head and neck reconstruction.

Electronic supplementary material

The online version of this article (10.1245/s10434-020-08732-y) contains supplementary material, which is available to authorized users.

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

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

The Use of Patient-Specific Implants in Oral and Maxillofacial Surgery

This article summarizes the current use of patient-specific implants in oral and maxillofacial surgery.

Computer guided temporomandibular joint reconstruction of Kaban III hemifacial microsomia with anotia: A case report

INTRODUCTION, Hemifacial microsomia is the second most common craniofacial congenital anomaly. It corresponds to a group of malformations ranging from minimal facial asymmetry to sever form affecting mandible, soft tissues, orbit, ear, and cranial nerves. PRESENTATION OF CASE, We present a case of 6 years old patient with Kaban class III hemifacial microsomia with anotia. Temporomandibular joint was reconstructed by costochondral graft using computer guided surgery (simulation and rapid prototyping). A computer guided soft tissue guide, mandibular, and maxillomandibular/zygomatic models were constructed using rapid prototyping technology. The customized computer guided soft tissue guide was used to localize the proper position of skin incision, the mandibular model was used for preoperative reconstruction plate bending, and the maxillomandibular/zygomatic model was used to estimate the rib graft length and position. Postoperative assessment showed proper positioning of the graft, with no complications or facial nerve affection. DISCUSSION, In this report, we introduce a new computer guided technique to estimate and identify the proper position of the temporomandibular joint graft based on patient CT. This technique eliminated the need of extended incisions with excessive dissection and provided a more accessible field for rib graft fixation, facilitating the surgical procedures. CONCLUSION, The use of computer guided surgery (simulation and rapid prototyping) for temporomandibular joint reconstruction in Kaban III hemifacial microsomia with anotia facilitates the surgical procedure, minimizes procedure time, increases precision, and reduces possible complications.

Review of surgical resection and reconstruction in head and neck cancer. Traditional versus current concepts

This review summarizes the development of head and neck cancer resection and reconstruction. The developments in the treatment of cancer patients are reflected in their surgical outcomes, in addition to functional and aesthetic improvements. New technologies, such as surgical simulation and planning, minimally invasive surgery, and microsurgery have been added to the field to improve surgical resection of the tumor and reconstruction. The field is still growing to optimize the management of head and neck cancer.

Validation study of 3D-printed anatomical models using 2 PLA printers for preoperative planning in trauma surgery, a human cadaver study

INTRODUCTION

3D printing contributes to a better understanding of the surgical approach, reduction and fixation of complex fractures. It is unclear how a 3D-printed model relates to a human bone. The accuracy of 3D-printed models is important to pre-bend plates and fit of surgical guides. We conduct a validation study in which we compare human cadavers with 3D-printed models to test the accuracy of 3D printing.

METHODS

Nine specimens were scanned, volume rendered into 3D reconstructions and saved as STL data. All models were in a ratio of 1:1 printed on the Ultimaker 3 and Makerbot Replicator Z18. Two independent observers measured all distances between the K-wires on the human cadavers, 2DCT, 3D reconstruction, Meshlab and both printers. A paired Samples T test was used to compare the measurements between the different modalities.

RESULTS

The least decrease in average distance in millimetres was seen in "the 3D printed pelvis 1", - 0.3 and - 0.8% on respectively the Ultimaker and Makerbot when compared with cadaver Pelvis (1) The 3D model of "Hand 2" showed the most decrease, - 2.5 and - 3.2% on the Ultimaker and Makerbot when compared with cadaver hand (2) Most significant differences in measurements were found in the conversion from 3D file into a 3D print and between the cadaver and 3D-printed model from the Makerbot.

CONCLUSION

Our 3D printing process results in accurate models suitable for preoperative workup. The Ultimaker 3 is slightly more accurate than the Makerbot Replicator Z18. We advise that medical professionals should perform a study that tests the accuracy of their 3D printing process before using the 3D-printed models in medical practice.

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

PURPOSE

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

The fitting accuracy of pre-bend reconstruction plates and their impact on the temporomandibular joint

BACKGROUND

Various causes for bone defects of the lower jaw have been described. As a result, patients often suffer from compromised aesthetics and a loss of, or reduction in, important physiological functions, such as swallowing, breathing, and speaking. A change in the shape of the lower jaw can impair the natural occlusion and leads to an atypical or modified position of the temporomandibular joint. Titanium reconstruction plates are the standard approach to jaw reconstruction, and are used for temporary bridging of a jaw defect or fixation of a bone graft. Conventionally these plates are intraoperatively adjusted to the mandible by the surgeon. Computer-aided manufacturing, computer-aided design, and rapid prototyping have gained increasing importance in the field of medicine, as they allow the production of individual models of the lower jaw, with the possibility of preoperatively bending the reconstruction plates. In this retrospective study, the accuracy of pre-bent titanium plates and their effect on the temporomandibular joint situation in comparison with intraoperatively curved plates will be discussed.

MATERIALS AND METHODS

Patients who attended our department for lower jaw reconstruction between March 2013 and February 2015 were included in this retrospective study. Within that time 20 patients were treated with pre-bent reconstruction plates (group 1). 20 comparable patients were selected with reconstruction and conventional intraoperative bending (group 2). To evaluate the accuracy of the plates and the condylar position, postoperative cone beam computed tomograms and computed tomograms were used to assess the bone-plate distance at 12 defined points and four angles in axial reconstruction. The results were compared, statistically evaluated, and discussed.

RESULTS

Regarding the maximum bone-plate distances and the sum of distances, there was a significant difference between the accuracy of the pre-bent and the conventionally bent reconstruction plates (p = 0.022, p = 0.048). Regarding the condylar position, there was no significant difference between both methods (p = 0.867).

CONCLUSION

The results of this study show that a better fitting accuracy can be achieved using pre-bent plates. Preparation of the plates proves to be advantageous and meaningful, especially in complex bone defects and deformations of the lower jaw. Nevertheless, concerning the position of the temporomandibular joint, no significant difference could be ascertained between the shown methods, contradicting several studies.

3D-printing techniques in a medical setting: a systematic literature review

BACKGROUND

Three-dimensional (3D) printing has numerous applications and has gained much interest in the medical world. The constantly improving quality of 3D-printing applications has contributed to their increased use on patients. This paper summarizes the literature on surgical 3D-printing applications used on patients, with a focus on reported clinical and economic outcomes.

METHODS

Three major literature databases were screened for case series (more than three cases described in the same study) and trials of surgical applications of 3D printing in humans.

RESULTS

227 surgical papers were analyzed and summarized using an evidence table. The papers described the use of 3D printing for surgical guides, anatomical models, and custom implants. 3D printing is used in multiple surgical domains, such as orthopedics, maxillofacial surgery, cranial surgery, and spinal surgery. In general, the advantages of 3D-printed parts are said to include reduced surgical time, improved medical outcome, and decreased radiation exposure. The costs of printing and additional scans generally increase the overall cost of the procedure.

CONCLUSION

3D printing is well integrated in surgical practice and research. Applications vary from anatomical models mainly intended for surgical planning to surgical guides and implants. Our research suggests that there are several advantages to 3D-printed applications, but that further research is needed to determine whether the increased intervention costs can be balanced with the observable advantages of this new technology. There is a need for a formal cost-effectiveness analysis.

Multicenter study on the use of patient-specific CAD/CAM reconstruction plates for mandibular reconstruction

PURPOSE

For the new generation of mandibular reconstruction, patient-specific mandible reconstruction plates (PSMPs) have been developed which are milled from titanium after preoperative computer planning using CAD/CAM procedures. Resection margins and plate position are determined by surgical guides. In addition, length and shape of the plate and the number and angulation of the screw holes can be planned.

METHODS

30 patients received such PSMP. Indication ranged from stabilization osteosynthesis, single alloplastic stand-alone reconstruction to microvascular reconstructions. Time for planning, fit of surgical guides and plates, pre-/postoperative occlusion, radiological position of the temporo mandibular joint and complications were recorded.

RESULTS

The median time for online planning was 35 min. The results concerning fit and handling of the PSMP and the surgical guides were mainly very positive. In six cases, the plan had to be adapted to the intraoperative clinical needs. The postoperative position of the condyles in the temporo mandibular fossae was regular in 28 cases. The evaluation of the occlusion was not representative due to not clearly identifiable occlusion in 2/3 of the cases. Nevertheless, complications like postoperative extraoral plate exposure, infection, graft and flap necrosis or difficulties to position the guides or the plate during surgery occurred.

CONCLUSIONS

Mandibular reconstruction with PSMP offers a broad range of opportunities and benefits compared with standard procedures and can be recommended for all kind of mandibular reconstructions. It is not yet foreseeable whether PSMP will in future become routine clinical practice for mandibular reconstruction or will be confined to selected isolated cases.

Accuracy of fibular sectioning and insertion into a rapid-prototyped bone plate, for mandibular reconstruction using CAD-CAM technology

Modern techniques of mandibular reconstruction, such as CAD-CAM technology and rapid prototyping, offer new means by which reconstructive surgery can be planned to optimise aesthetic outcomes and prosthetic rehabilitation. The high degree of accuracy afforded by these approaches is principally attributable to high-precision fibular sectioning and insertion of the bone into a customised bone plate. CAD-CAM mandibular reconstruction procedures using vascularised bone free-flap transfers were performed on 10 patients with benign or malignant neoplasms. Five were not treated with the aid of CAD-CAM technology, and served as the control group. Five were scheduled for maxillofacial surgery using surgical cutting guides and customised bone plates. A generalised linear model for linear measures was used to compare the accuracy of reconstruction between the two groups. A difference, even though not significant, in the lateral shift of the mesial and distal positions of the fibular units was evident between groups. CAD-CAM-generated fibular surgical guides afford improved accuracy when used to restore native anatomy, especially in the context of mandibular arch restoration, and both operating room time and related costs are reduced during fibular sectioning.