Low-Cost 3D Printing Orbital Implant Templates in Secondary Orbital Reconstructions

Classical Orbital Floor Post-Traumatic Reconstruction vs. Customized Reconstruction with the Support of "In-House" 3D-Printed Models: A Retrospective Study with an Analysis of Volumetric Measurement

BACKGROUND

Orbital floor fractures (OFFs) represent an interesting chapter in maxillofacial surgery, and one of the main challenges in orbit reconstruction is shaping and cutting the precise contour of the implants due to its complex anatomy.

OBJECTIVE

The aim of the retrospective study was to demonstrate, through pre- and postoperative volumetric measurements of the orbit, how the use of a preformed titanium mesh based on the stereolithographic model produced with 3D printers ("In-House" reconstruction) provides a better reconstruction volumetric compared to the intraoperatively shaped titanium mesh.

MATERIALS AND METHODS

The patients with OFF enrolled in this study were divided into two groups according to the inclusion criteria. In Group 1 (G1), patients surgically treated for OFF were divided into two subgroups: G1a, patients undergoing orbital floor reconstruction with an intraoperatively shaped mesh, and G1b, patients undergoing orbital floor reconstruction with a preoperative mesh shaped on a 3D-printed stereolithographic model. Group 2 (G2) consisted of patients treated for other traumatic pathologies (mandible fractures and middle face fractures not involving orbit). Pre- and postoperative orbital volumetric measurements were performed on both G1 and G2. The patients of both groups were subjected to the measurement of orbital volume using Osirix software (Pixmeo SARL, CH-1233 Bernex, Switzerland) on the new CT examination. Both descriptive (using central tendency indices such as mean and range) and regressive (using the Bravais-Pearson index, calculated using the GraphPad program) statistical analyses were performed on the recorded data.

RESULTS

From 1 January 2017 to 31 December 2021, of the 176 patients treated for OFF at the "Magna Graecia" University Hospital of Catanzaro 10 fulfilled the study's inclusion criteria: 5 were assigned to G1a and 5 to G1b, with a total of 30 volumetric measurements. In G2, we included 10 patients, with a total of 20 volumetric measurements. From the volumetric measurements and statistical analysis carried out, it emerged that the average of the volumetric differences of the healthy orbits was ±0.6351 cm3, the standard deviation of the volumetric differences was ±0.3383, and the relationship between the treated orbit and the healthy orbit was linear; therefore, the treated orbital volumes tend to approach the healthy ones after surgical treatment.

CONCLUSION

This study demonstrates that if the volume is restored within the range of the standardized mean, the diplopia is completely recovered already after surgery or after one month. For orbital volumes that do not fall within this range, functional recovery could occur within 6 months or be lacking. The restoration of the orbital volume using pre-modeled networks on the patient's anatomical model, printed internally in 3D, allows for more accurate reconstructions of the orbital floor in less time, with clinical advantages also in terms of surgical timing.

Polymers in 3D printing of external maxillofacial prostheses and in their retention systems

Maxillofacial defects, arising from trauma, oncological disease or congenital abnormalities, detrimentally affect daily life. Prosthetic repair offers the aesthetic and functional reconstruction with the help of materials mimicking natural tissues. 3D polymer printing enables the design of patient-specific prostheses with high structural complexity, as well as rapid and low-cost fabrication on-demand. However, 3D printing for prosthetics is still in the early stage of development and faces various challenges for widespread use. This is because the most suitable polymers for maxillofacial restoration are soft materials that do not have the required printability, mechanical strength of the printed parts, as well as functionality. This review focuses on the challenges and opportunities of 3D printing techniques for production of polymer maxillofacial prostheses using computer-aided design and modeling software. Review discusses the widely used polymers, as well as their blends and composites, which meet the most important assessment criteria, such as the physicochemical, biological, aesthetic properties and processability in 3D printing. In addition, strategies for improving the polymer properties, such as their printability, mechanical strength, and their ability to print multimaterial and architectural structures are highlighted. The current state of the prosthetic retention system is presented with a focus on actively used polymer adhesives and the recently implemented prosthesis-supporting osseointegrated implants, with an emphasis on their creation from 3D-printed polymers. The successful prosthetics is discussed in terms of the specificity of polymer materials at the restoration site. The approaches and technological prospects are also explored through the examples of the nasal, auricle and ocular prostheses, ranging from prototypes to end-use products.

Patient-Specific Implant Customization for Treatment of Internal Orbital Fractures Using Office-Based Three-Dimensional Printing

OBJECTIVE

Three-dimensional (3D) modeling technology aids the reconstructive surgeon in designing and tailoring individualized implants for the reconstruction of complex craniofacial fractures. Three-dimensional modeling and printing have traditionally been outsourced to commercial vendors but can now be incorporated into both private and academic craniomaxillofacial practices. The goal of this report is to present a low-cost, standardized office-based workflow for restoring bony orbital volume in traumatic orbital fractures.

METHODS

Patients with internal orbital fractures requiring open repair were identified. After the virtual 3D models were created by iPlan 3.0 Cranial CMF software (Brainlab), the models were printed using an office-based 3D printer to shape and modify orbital plates to correctly fit the fracture defect. The accuracy of the anatomic reduction and the restored bony orbital volume measurements were determined using postoperative computed tomography images and iPlan software.

RESULTS

Nine patients fulfilled the inclusion criteria: 8 patients had unilateral fractures and 1 patient had bilateral fractures. Average image processing and print time were 1.5 hours and 3 hours, respectively. The cost of the 3D printer was $2500 and the average material cost to print a single orbital model was $2. When compared with the uninjured side, the mean preoperative orbital volume increase and percent difference were 2.7 ± 1.3 mL and 10.9 ± 5.3%, respectively. Postoperative absolute volume and percent volume difference between the orbits were -0.2 ± 0.4 mL and -0.8 ± 1.7%, respectively.

CONCLUSIONS

Office-based 3D printing can be routinely used in the repair of internal orbital fractures in an efficient and cost-effective manner to design the implant with satisfactory patient outcomes.

Effect of Sterilization on the Dimensional and Mechanical Behavior of Polylactic Acid Pieces Produced by Fused Deposition Modeling

To successfully implement additive manufacturing (AM) techniques for custom medical device (MD) production with low-cost resources, it is imperative to understand the effect of common and affordable sterilization processes, such as formaldehyde or steam sterilization, on pieces manufactured by AM. In this way, the performance of low-risk MDs, such as biomodels and surgical guides, could be assessed for complying with safety, precision, and MD delivery requirements. In this context, the aim of the present work was to evaluate the effect of formaldehyde and steam sterilization on the dimensional and mechanical stability of standard polylactic acid (PLA) test pieces produced by fused deposition modeling (FDM). To achieve this, PLA samples were sterilized according to the sterilization protocol of a public hospital in the city of Bucaramanga, Colombia. Significant changes regarding mechanical and dimensional properties were found as a function of manufacturing parameters. This research attempts to contribute to the development of affordable approaches for the fabrication of functional and customized medical devices through AM technologies, an issue of particular interest for low- and middle-income countries.

Patient-Specific Orbital Implants Vs. Pre-Formed Implants for Internal Orbital Reconstruction

PURPOSE

To compare the outcome of orbital blowout fracture repair by means of pre-formed porous-polyethylene titanium implants (PFI) vs patient-specific porous-polyethylene implants (PSI).

METHODS

Retrospective cohort study. Baseline characteristics, ophthalmic examination results, ocular motility, fracture type, the timing of surgery, implant type, and final relative enophthalmos of all patients operated on for blow-out fractures in a single center were collected and analyzed.

RESULTS

Twenty-seven patients (mean age 39 years, 9 females) were enrolled. Sixteen underwent fracture repair with PFI and 11 with PSI at 11 months (median) post-trauma. Mean follow-up duration was 1.1 years. Both groups showed significant postoperative improvement in primary or vertical gaze diplopia (P = .03, χ²). Relative enophthalmos improved from -3.2 preoperative PFI to -1.7 mm postoperative PFI, and from -3.0 mm preoperative PSI to -1.1 mm postoperative PSI (P= .1). PSI patients had non-significantly less postoperative enophthalmos and globe asymmetry than PFI patients. The outcome was not influenced by previous surgery, age, sex, number of orbital walls involved in the initial trauma, or medial wall involvement (linear regression). Both groups sustained complications unrelated to implant choice.

CONCLUSION

Both PSI and PFI yielded good outcomes in this study. PSI may be a good alternative to PFI in primary or secondary orbital blowout fracture repair with less enophthalmos and globe asymmetry, in spite of the possible disadvantages of production time, a relatively larger design, and challenging insertion. Since it is a mirror image of the uninjured orbit, it may be beneficial in extensive fractures.

Biomedical applications of three-dimensional bioprinted craniofacial tissue engineering

Anatomical complications of the craniofacial regions often present considerable challenges to the surgical repair or replacement of the damaged tissues. Surgical repair has its own set of limitations, including scarcity of the donor tissues, immune rejection, use of immune suppressors followed by the surgery, and restriction in restoring the natural aesthetic appeal. Rapid advancement in the field of biomaterials, cell biology, and engineering has helped scientists to create cellularized skeletal muscle-like structures. However, the existing method still has limitations in building large, highly vascular tissue with clinical application. With the advance in the three-dimensional (3D) bioprinting technique, scientists and clinicians now can produce the functional implants of skeletal muscles and bones that are more patient-specific with the perfect match to the architecture of their craniofacial defects. Craniofacial tissue regeneration using 3D bioprinting can manage and eliminate the restrictions of the surgical transplant from the donor site. The concept of creating the new functional tissue, exactly mimicking the anatomical and physiological function of the damaged tissue, looks highly attractive. This is crucial to reduce the donor site morbidity and retain the esthetics. 3D bioprinting can integrate all three essential components of tissue engineering, that is, rehabilitation, reconstruction, and regeneration of the lost craniofacial tissues. Such integration essentially helps to develop the patient-specific treatment plans and damage site-driven creation of the functional implants for the craniofacial defects. This article is the bird's eye view on the latest development and application of 3D bioprinting in the regeneration of the skeletal muscle tissues and their application in restoring the functional abilities of the damaged craniofacial tissue. We also discussed current challenges in craniofacial bone vascularization and gave our view on the future direction, including establishing the interactions between tissue-engineered skeletal muscle and the peripheral nervous system.

Virtual Planning and 3D Printing in the Management of Acute Orbital Fractures and Post-Traumatic Deformities

Virtual surgical planning (VSP) and three-dimensional (3D) printing have advanced surgical reconstruction of orbital defects. Individualized 3D models of patients' orbital bony and soft tissues provide the surgeon with corrected orbital volume based on normalized anatomy, precise location of critical structures, and when needed a better visualization of the defect or altered anatomy that are paramount in preoperative planning. The use of 3D models preoperatively allows surgeons to improve the accuracy and safety of reconstruction, reduces intraoperative time, and most importantly lowers the rate of common postoperative complications, including over- or undercontouring of plates, orbital implant malposition, enophthalmos, and hypoglobus. As 3D printers and materials become more accessible and cheaper, the utility of printing patient-specific implants becomes more feasible. This article summarizes the traditional surgical management of orbital fractures and reviews advances in VSP and 3D printing in this field. It also discusses the use of in-house (point-of-care) VSP and 3D printing to further advance care of acute orbital trauma and posttraumatic deformities.

Point-of-Care Virtual Surgical Planning and 3D Printing in Oral and Cranio-Maxillofacial Surgery: A Narrative Review

This paper provides an overview on the use of virtual surgical planning (VSP) and point-of-care 3D printing (POC 3DP) in oral and cranio-maxillofacial (CMF) surgery based on a literature review. The authors searched PubMed, Web of Science, and Embase to find papers published between January 2015 and February 2022 in English, which describe human applications of POC 3DP in CMF surgery, resulting in 63 articles being included. The main review findings were as follows: most used clinical applications were anatomical models and cutting guides; production took place in-house or as "in-house-outsourced" workflows; the surgeon alone was involved in POC 3DP in 36 papers; the use of free versus paid planning software was balanced (50.72% vs. 49.27%); average planning time was 4.44 h; overall operating time decreased and outcomes were favorable, though evidence-based studies were limited; and finally, the heterogenous cost reports made a comprehensive financial analysis difficult. Overall, the development of in-house 3D printed devices supports CMF surgery, and encouraging results indicate that the technology has matured considerably.

Patient-specific Implants for Orbital Fractures: A Systematic Review

PURPOSE

Orbital fractures are common facial fractures that can be challenging to repair and require careful attention to avoid unacceptable ophthalmic complications. Customized implants that are unique to an individual patient, or patient-specific implants (PSIs), have been increasingly used to repair orbital wall fractures. This systematic review summarizes the current evidence regarding custom-made orbital wall implants.

METHODS

A keyword search of published literature from January 2010 to September 2021 was performed using Ovid MEDLINE, PubMed, and the Cochrane Library databases. Original articles that included more than 3 human subjects with an orbital fracture repaired with a PSI were included. The search results were reviewed, duplicates were removed and relevant articles were included for analysis.

RESULTS

Fifteen articles meeting the inclusion criteria. The articles were categorized into 3 separate groups based on the method of PSI fabrication: manual molding of a PSI on a 3D-printed orbital model (53%), directly from a 3D printer (27%), or via a template fabricated from a 3D printer (20%). Three primary postoperative outcomes were assessed: rates of diplopia, enophthalmos, and orbital volume. Postoperative rates of diplopia and enophthalmos improved regardless of the PSI technique, and postoperative orbital volumes were reduced compared with their preoperative state. When PSIs were compared to conventional implants, patient outcomes were comparable.

CONCLUSIONS

This review of existing PSI orbital implant literature highlights that while PSI can accurately and safely repair orbital fractures, patient outcomes are largely comparable to orbital fractures repaired by conventional methods, and PSI do not offer a definitive benefit over conventional implants.

Guide for starting or optimizing a 3D printing clinical service

Three-dimensional (3D) printing has applications in many fields and has gained substantial traction in medicine as a modality to transform two-dimensional scans into three-dimensional renderings. Patient-specific 3D printed models have direct patient care uses in surgical and procedural specialties, allowing for increased precision and accuracy in developing treatment plans and guiding surgeries. Medical applications include surgical planning, surgical guides, patient and trainee education, and implant fabrication. 3D printing workflow for a laboratory or clinical service that produces anatomic models and guides includes optimizing imaging acquisition and post-processing, segmenting the imaging, and printing the model. Quality assurance considerations include supervising medical imaging expert radiologists' guidance and self-implementing in-house quality control programs. The purpose of this review is to provide a workflow and guide for starting or optimizing laboratories and clinical services that 3D-print anatomic models or guides for clinical use.

Benign bony tumors of the paranasal sinuses, orbit, and skull base

Benign bony tumors of the skull base and paranasal sinuses are uncommon entities, with an overall higher incidence in males. Benign bony tumors may lead to local expansion with resultant mass effect of potentially critical structures. Some benign bony tumors may undergo malignant transformation. This article reviews the presentation and management of benign bone tumors of the skull base and paranasal sinuses with special consideration to involvement of the adjacent orbit, intracranial and critical neurovascular structures. This review covers tumor incidence, location, gross and histologic appearance as well as radiographic findings, treatment, and recurrence rates. Tumors discussed in this article include osteochondromas, osteomas, osteoid osteomas, aneurysmal bone cysts, fibrous dysplasia, giant cell tumors, cemento-ossifying fibroma, ameloblastic fibro-odontoma, ecchordosis physaliphora, chondromyxoid fibroma, primary chronic osteomyelitis, primary chronic osteomyelitis, osteochondromyxoma, and dense bone islands.

3D Printing in Eye Care

Three-dimensional printing enables precise modeling of anatomical structures and has been employed in a broad range of applications across medicine. Its earliest use in eye care included orbital models for training and surgical planning, which have subsequently enabled the design of custom-fit prostheses in oculoplastic surgery. It has evolved to include the production of surgical instruments, diagnostic tools, spectacles, and devices for delivery of drug and radiation therapy. During the COVID-19 pandemic, increased demand for personal protective equipment and supply chain shortages inspired many institutions to 3D-print their own eye protection. Cataract surgery, the most common procedure performed worldwide, may someday make use of custom-printed intraocular lenses. Perhaps its most alluring potential resides in the possibility of printing tissues at a cellular level to address unmet needs in the world of corneal and retinal diseases. Early models toward this end have shown promise for engineering tissues which, while not quite ready for transplantation, can serve as a useful model for in vitro disease and therapeutic research. As more institutions incorporate in-house or outsourced 3D printing for research models and clinical care, ethical and regulatory concerns will become a greater consideration. This report highlights the uses of 3D printing in eye care by subspecialty and clinical modality, with an aim to provide a useful entry point for anyone seeking to engage with the technology in their area of interest.

Patient specific implants in orbital reconstruction: A pilot study

Purpose

Successful repair of the orbital skeleton restores function and cosmesis by normalizing globe position and allowing full motility of the extraocular muscles. Routine repairs are successful with standard implants. However, defects that are irregular or cause volume deficiency can be challenging to repair. The development of patient specific implants (PSI) offers an additional tool in complex cases. Herein, we report our experience using PSI for orbital reconstruction.

Methods

An IRB-approved review was conducted of consecutive patients who received PSI from 8/2016–9/2018. Demographic and examination findings were recorded. PSI was designed using high-density porous polyethylene or polyetheretherketone (PEEK) and implanted for repair. The postoperative course was reviewed for outcomes and complications.

Results

Eight patients were identified. Two had silent sinus syndrome, 3 were complex facial fracture revisions, and 3 were post-oncologic reconstruction. Seven received porous polyethylene implants, and 1 had a PEEK implant. Mean follow up time was 10.2 months (3.3–28.3). All had an improved functional and aesthetic result. Diplopia and enophthalmos completely resolved in 60% of fracture and silent sinus patients. All fracture and silent sinus patients were orthotropic without diplopia in primary gaze at last follow up. Tumor patients had improvement in symmetry and functionality. There were no complications.

Conclusion and importance

Complex orbital skeleton derangements can be difficult to repair and standard implants may incompletely resolve the anatomic problem. In challenging cases, PSI may better achieve an aesthetically and anatomically successful outcome and improve functionality.

A review of additive manufacturing applications in ophthalmology

Additive Manufacturing (AM) capabilities in terms of product customization, manufacture of complex shape, minimal time, and low volume production those are very well suited for medical implants and biological models. AM technology permits the fabrication of physical object based on the 3D CAD model through layer by layer manufacturing method. AM use Magnetic Resonance Image (MRI), Computed Tomography (CT), and 3D scanning images and these data are converted into surface tessellation language (STL) file for fabrication. The applications of AM in ophthalmology includes diagnosis and treatment planning, customized prosthesis, implants, surgical practice/simulation, pre-operative surgical planning, fabrication of assistive tools, surgical tools, and instruments. In this article, development of AM technology in ophthalmology and its potential applications is reviewed. The aim of this study is nurturing an awareness of the engineers and ophthalmologists to enhance the ophthalmic devices and instruments. Here some of the 3D printed case examples of functional prototype and concept prototypes are carried out to understand the capabilities of this technology. This research paper explores the possibility of AM technology that can be successfully executed in the ophthalmology field for developing innovative products. This novel technique is used toward improving the quality of treatment and surgical skills by customization and pre-operative treatment planning which are more promising factors.

Comparison of Nasoseptal Cartilage Graft Versus Titanium Mesh in Reconstruction of Pure Orbital Blowout Fractures

PURPOSE

To compare the efficacy of nasoseptal cartilage grafts versus titanium mesh implants in pure orbital blowout fractures.

METHODS

A retrospective review was performed on 48 patients who had surgical repair of an orbital fracture. Patients who underwent pure orbital blowout fracture repair with either nasoseptal cartilage grafts or titanium mesh implants and at least 1 year postoperative follow-up were included in the study. The clinical features and treatment outcomes were analyzed.

RESULTS

Twenty-five patients fulfilled our study criteria and were included in the analyses. Nasoseptal graft was used in 12 patients (48%) while titanium mesh was preferred in 13 patients (52%). Preoperative clinical features including age, size of the floor defect, and preoperative clinical findings (enophthalmos, diplopia, and restriction of ocular motility) were similar between 2 groups. Mean postoperative follow-up was 14.7 ± 2.3 months in the nasoseptal group while it was 16.1 ± 2.5 months in the titanium group (P = 0.84). Diplopia and ocular motility limitation were resolved in all patients at the last postoperative follow-up visit, while 1 patient in each group had enophthalmos (8.3% versus 7.6%, P = 1.0). No patient in the nasoseptal group experienced postoperative complications while 2 patients in the titanium group (15.3%) developed material-related complications (P = 0.48).

CONCLUSIONS

Long-term clinical results of nasoseptal cartilage grafts and titanium mesh implants in pure orbital blowout fractures with preoperative floor defects smaller than 4 cm2 were comparable. Nasoseptal cartilage grafts may be preferred in patients with septal deviation and no spurs or turbinate hypertrophy.

3D printed rodent skin-skull-brain model: A novel animal-free approach for neurosurgical training

In neuroscience, stereotactic brain surgery is a standard yet challenging technique for which laboratory and veterinary personnel must be sufficiently and properly trained. There is currently no animal-free training option for neurosurgeries; stereotactic techniques are learned and practiced on dead animals. Here we have used three-dimensional (3D) printing technologies to create rat and mouse skin-skull-brain models, specifically conceived for rodent stereotaxic surgery training. We used 3D models obtained from microCT pictures and printed them using materials that would provide the most accurate haptic feedback for each model—PC-ABS material for the rat and Durable resin for the mouse. We filled the skulls with Polyurethane expanding foam to mimic the brain. In order to simulate rodent skin, we added a rectangular 1mm thick clear silicone sheet on the skull. Ten qualified rodent neurosurgeons then performed a variety of stereotaxic surgeries on these rat and mouse 3D printed models. Participants evaluated models fidelity compared to cadaveric skulls and their appropriateness for educational use. The 3D printed rat and mouse skin-skull-brain models received an overwhelmingly positive response. They were perceived as very realistic, and considered an excellent alternative to cadaveric skulls for training purposes. They can be made rapidly and at low cost. Our real-size 3D printed replicas could enable cost- and time-efficient, animal-free neurosurgery training. They can be absolute replacements for stereotaxic surgery techniques practice including but not limited to craniotomies, screw placement, brain injections, implantations and cement applications. This project is a significant step forward in implementing the replacement, reduction, and refinement (3Rs) principles to animal experimentation. These 3D printed models could lead the way to the complete replacement of live animals for stereotaxic surgery training in laboratories and veterinary studies.

Patient-Specific Implants in Oculofacial Plastic Surgery

PURPOSE

To investigate how patient-specific implants (PSIs) are being utilized for periocular facial skeletal reconstruction. Specifically, to characterize indications for custom implants, areas of reconstruction, intraoperative variables impacting implant placement, as well as to report on postoperative outcomes.

MATERIALS AND METHODS

A retrospective chart review was performed for patients who received a PSI for periocular skeletal reconstruction between 2015 and 2019. Three independent academic centers were included in this study, which encompassed 4 different primary surgeons. Medical records, radiographic imaging, and operative reports were reviewed.

RESULTS

Eleven patients, 8 females and 3 males, ages ranging from 15 to 63 years old received PSIs. The average duration of follow up was 16 months ± 6.6 months (range: 9-30 months). The most common underlying etiology for reconstruction was prior trauma (54.5%) followed by benign tumor resection (18.2%). The most frequent area of reconstruction involved the inferior orbital rim and adjacent maxilla (63.6%). Implant materials included porous polyethylene, polyetheretherketone, and titanium. Six implants required intraoperative modification, most commonly accommodate critical neurovascular structures (66.6%) or improve contour (33.3%). Two postoperative complications were noted, both in the form of infection with 1 implant requiring removal.

CONCLUSIONS

Reconstruction of complex facial skeletal defects can be achieved by utilizing computer-assisted design software and 3D printing techniques to create PSIs. These implants represent the most customizable option for symmetric restoration of the facial skeleton by not only addressing structural deficits but also volumetric loss. This was particularly apparent in reconstruction of the orbital rim and midface. PSIs were found to be of most benefit in patients with prior trauma or complex skeletal defects after tumor resection.

Orbital Bony Reconstruction With Presized and Precontoured Porous Polyethylene-Titanium Implants

PURPOSE

Complex bony orbital defects are reconstructively challenging due to loss of intraoperative anatomical landmarks and adjacent support. Presized and precontoured porous polyethylene-titanium implants (Medpor Titan 3D Orbital Floor Implant) are designed to reestablish normal orbital floor and medial wall anatomy and are modeled after anatomically averaged orbits. This is the first study to report clinical outcomes with this implant.

METHODS

This retrospective case series reviewed clinical data and outcomes for patients undergoing orbital reconstruction with a presized and precontoured porous polyethylene-titanium orbital implant from January 2016 to June 2018.

RESULTS

A total of 34 orbits of 33 patients were identified (mean age: 43 ± 16 years, 70% men). Most bony defects were a result of trauma and included large orbital floor deformities (100%), medial wall defects (74%), disrupted inferomedial struts (68%), and broken posterior ledges (82%). Symptomatic diplopia (73%) and enophthalmos (89%, mean: 3.7 ± 2.1 mm) were common preoperatively. Many cases were revisions (44%). Mean follow up was 7.8 ± 6.7 months. All patients had improved globe positioning, enophthalmos, and hypoglobus. Seven patients had persistent postoperative diplopia: 6 responded to prism therapy and 1 required strabismus surgery. One patient required retrobulbar hematoma drainage and 1 patient required implant explantation due to chronic infection.

CONCLUSIONS

Commercially available presized and precon toured porous polyethylene-titanium implants are useful for complex orbital bony defects and can achieve functional improve ments in diplopia, enophthalmos, and extraocular motility with a low incidence of postoperative complications or revisional surgery.

Customized Orbit and Frontal Bone Implants

Orbitocranial reconstruction objectives include creation of a solid barrier between intracranial contents and the environment allowing restoration of physiologic homeostasis and restoration of aesthetic craniofacial contours. Historically, bone grafts have been used for reconstruction but were fraught with unpredictable resorption and imperfect contouring given the complex anatomy of the orbitofrontal bones. With advances in three-dimensional modeling technology, alloplastic custom implants in orbital and frontal bone reconstruction have allowed for rapid fixation reducing surgical times and improved cosmesis.

Theoretical model of pediatric orbital trapdoor fractures and provisional personalized 3D printing-assisted surgical solution

Pediatric orbital trapdoor fractures are common in children and adolescents and usually require emergency surgical intervention. Herein, a personalized 3D printing-assisted approach to surgical treatment is proposed, serving to accurately and effectively repair pediatric orbital trapdoor fractures. We first investigated stress distribution in external force-induced orbital blowout fractures via numerical simulation, determining that maximum stresses on inferior and medial walls exceed those on superior and lateral walls and thus confer higher probability of fracture. We also examined 36 pediatric patients treated for orbital trapdoor fractures between 2014 and 2019 to verify our theoretical construct. Using 3D printing technique, we then created orbital models based on computed tomography (CT) studies of these patients. Absorbable implants were tailor-made, replicating those of 3D-printed models during surgical repairs of fractured orbital bones. As follow-up, we compared CT images and clinical parameters (extraocular movements, diplopia, enophthalmos) before and 12 months after operative procedures. There were only two patients with diplopia and six with enophthalmos >2 mm at 12 months, attesting to the efficacy of our novel 3D printing-assisted strategy.

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Numerical simulation is used to theoretically investigate the mechanism of external force-induced orbital blowout fractures.

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3D printing--assisted surgical treatment is proposed to effectively repair pediatric orbital trapdoor fractures.

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Clinical studies are performed by repairing fractured orbital bones via 3D printed customized absorbable implants.

Cost Analysis for In-house versus Industry-printed Skull Models for Acute Midfacial Fractures

Industry-printed (IP) 3-dimensional (3D) models are commonly used for secondary midfacial reconstructive cases but not for acute cases due to their high cost and long turnaround time. We have begun using in-house (IH) printed models for complex unilateral midface trauma. We hypothesized that IH models would decrease cost and turnaround time, compared with IP models.

Three-Dimensional Analysis of Isolated Orbital Floor Fractures Pre- and Post-Reconstruction with Standard Titanium Meshes and "Hybrid" Patient-Specific Implants

The aim of this study was to compare the efficacy of the intraoperative bending of titanium mesh with the efficacy of pre-contoured “hybrid” patient-specific titanium mesh for the surgical repair of isolated orbital floor fractures. In-house 3D-printed anatomical models were used as bending guides. The main outcome measures were preoperative and postoperative orbital volume and surgery time. We performed a retrospective cohort study including 22 patients who had undergone surgery between May 2016 and November 2018. The first twelve patients underwent conventional reconstruction with intraoperative free-hand bending of an orbital floor mesh plate. The subsequent ten patients received pre-contoured plates based on 3D-printed orbital models that were produced by mirroring the non-fractured orbit of the patient using a medical imaging software. We compared the preoperative and postoperative absolute volume difference (unfractured orbit, fractured orbit), the fracture area, the fracture collapse, and the effective surgery time between the two groups. In comparison to the intraoperative bending of titanium mesh, the application of preformed plates based on a 3D-printed orbital model resulted in a non-significant absolute volume difference in the intervention group (p = 0.276) and statistically significant volume difference in the conventional group (p = 0.002). Further, there was a significant reduction of the surgery time (57.3 ± 23.4 min versus 99.8 ± 28.9 min, p = 0.001). The results of this study suggest that the use of 3D-printed orbital models leads to a more accurate reconstruction and a time reduction during surgery.

3D Printed Personalized Corneal Models as a Tool for Improving Patient’s Knowledge of an Asymmetric Disease

Additive manufacturing is a vanguard technology that is currently being used in several fields in medicine. This study aims to evaluate the viability in clinical practice of a patient-specific 3D model that helps to improve the strategies of the doctor-patient assistance. Data obtained from a corneal topographer were used to make a virtual 3D model by using CAD software, to later print this model by FDM and get an exact replica of each patient’s cornea in consultation. Used CAD and printing software were open-source, and the printing material was biodegradable and its cost was low. Clinic users gave their feedback by means of a survey about their feelings when perceiving with their senses their own printed cornea. There was 82 surveyed, 73.8% (9.74; SD: 0.45) of them considered that the model had helped them a lot to understand their disease, expressing 100% of them their intention of taking home the printed model. The majority highlighted that this new concept improves both quality and clinical service in consultation. Custom-made individualized printed models allow a new patient-oriented perspective that may improve the communication strategy from the ophthalmologist to the patient, easing patient’s understanding of their asymmetric disease and its later treatment.

Advances in bioprinting using additive manufacturing

Since its conception in the 1980's, several advances in the field of additive manufacturing have led to exploration of alternate as well as combination biomaterials. These progresses have directed the use of 3D printing in wider applications such as printing of dermal layers, cartilage, bone defects, and surgical implants. Furthermore, the incorporation of live and functional cells with or atop biomaterials has laid the foundation for its use in tissue engineering. The purpose of this review is to summarize the advances in 3D printing and bioprinting of several types of tissues such as skin, cartilage, bones, and cardiac valves. This review will address the current 3D technologies used in tissue construction and study the biomaterials being investigated. There are several requirements that need to be addressed, in order to reconstruct functional tissue such as mechanical strength, porosity of the replicate and cellular incorporation. Researchers have focused their studies to answer questions regarding these requirements.

Applications of three-dimensional printing in orbital diseases and disorders

PURPOSE OF REVIEW

To comprehensively review the applications of advanced three-dimensional printing technology in the management of orbital abnormalities.

RECENT FINDINGS

Three-dimensional printing has added value in the preoperative planning and manufacturing of patient-specific implants and surgical guides in the reconstruction of orbital trauma, congenital defects and tumor resection. In view of the costs and time, it is reserved as strategy for large and complex craniofacial cases, in particular those including the bony contour. There is anecdotal evidence of a benefit of three-dimensional printing in the manufacturing of prostheses for the exenterated and anophthalmic socket, and in the fabrication of patient-specific boluses, applicators and shielding devices for orbital radiation therapy. In addition, three-dimensional printed healthy and diseased orbits as phantom tangible models may augment the teaching and learning process of orbital surgery.

SUMMARY

Three-dimensional printing allows precision treatment tailored to the unique orbital anatomy of the patient. Advancement in technology and further research are required to support its wider use in orbital clinical practice.

Implementations of 3D printing in ophthalmology

PURPOSE

The purpose of this paper is to provide an in-depth understanding of how to best utilize 3D printing in medicine, and more particularly in ophthalmology in order to enhance the clinicians' ability to provide out-of-the-box solutions for unusual challenges that require patient personalization. In this review, we discuss the main applications of 3D printing for diseases of the anterior and posterior segments of the eye and discuss their current status and implementation. We aim to raise awareness among ophthalmologists and report current and future developments.

METHODS

A computerized search from inception up to 2018 of the online electronic database PubMed was performed, using the following search strings: "3D," "printing," "ophthalmology," and "bioprinting." Additional data was extracted from relevant websites. The reference list in each relevant article was analyzed for additional relevant publications.

RESULTS

3D printing first appeared three decades ago. Nevertheless, the implementation and utilization of this technology in healthcare became prominent only in the last 5 years. 3D printing applications in ophthalmology are vast, including organ fabrication, medical devices, production of customized prosthetics, patient-tailored implants, and production of anatomical models for surgical planning and educational purposes.

CONCLUSIONS

The potential applications of 3D printing in ophthalmology are extensive. 3D printing enables cost-effective design and production of instruments that aid in early detection of common ocular conditions, diagnostic and therapeutic devices built specifically for individual patients, 3D-printed contact lenses and intraocular implants, models that assist in surgery planning and improve patient and medical staff education, and more. Advances in bioprinting appears to be the future of 3D printing in healthcare in general, and in ophthalmology in particular, with the emerging possibility of printing viable tissues and ultimately the creation of a functioning cornea, and later retina. It is expected that the various applications of 3D printing in ophthalmology will become part of mainstream medicine.

Low-cost three-dimensional printed orbital template-assisted patient-specific implants for the correction of spherical orbital implant migration

PURPOSE

To describe the outcomes of a patient-specific implant (PSI), fabricated using a three-dimensional (3D) printed orbital template and placed in the basin of the inferior orbital fissure to correct inferotemporally migrated spherical orbital implant.

METHODS

This is a single-center, prospective, consecutive, interventional, case series of six patients, with non-porous, spherical, orbital implant migration that underwent implant recentration surgically with a novel technique. Migration was subclassified either as decentration that did not affect the prosthetic retention or as displacement that affected the prosthetic retention in the eye socket. Only implant displacements were treated. The primary outcome measure was centration of the implant clinically and radiologically, with ability to retain the prosthesis.

RESULTS

At a mean follow-up of 21 months, all six orbital spherical implants remained centered. There were no cases of extrusion, exposure, or migration of either implants. There were no cases of PSI displacement. Additional procedures to optimize the aesthetic outcome of the customized ocular prosthesis (COP) required were simultaneous fornix formation suture in three patients, subsequent fornix formation with mucus membrane graft in two patients, and levator resection and sulcus hyaluronic acid gel injection in one patient each. The mean PSI implant weight was 2.66 ± 0.53 g. The mean COP weight was 2.2 ± 0.88 g postoperatively. The median patient satisfaction with the procedure was 9 on 10.

CONCLUSION

A 3D printing-assisted PSI placed in the basin of the inferior orbital fissure allows recentration of the migrated implant over a follow-up of 21 months without complications.

Generation of customized orbital implant templates using 3-dimensional printing for orbital wall reconstruction

OBJECTIVES

To describe and evaluate a novel surgical approach to orbital wall reconstruction that uses three-dimensionally (3D) printed templates to mold a customized orbital implant.

METHODS

A review was conducted of 11 consecutive patients who underwent orbital wall reconstruction using 3D-printed customized orbital implant templates. In these procedures, the orbital implant was 3D pressed during surgery and inserted into the fracture site. The outcomes of this approach were analyzed quantitatively by measuring the orbital tissue volumes within the bony orbit using computed tomography.

RESULTS

All 11 orbital wall reconstructions (6 orbital floor and 5 medial wall fractures) were successful with no post operative ophthalmic complications. Statistically significant differences were found between the preoperative and post operative orbital tissue volumes for the affected orbit (24.00 ± 1.74 vs 22.31 ± 1.90 cm³; P = 0.003). There was no statistically significant difference found between the tissue volume of the contralateral unaffected orbit and the affected orbit after reconstruction (22.01 ± 1.60 cm³ vs 22.31 ± 1.90 cm³; P = 0.182).

CONCLUSION

3D-printed customized orbital implant templates can be used to press and trim conventional implantable materials with patient-specific contours and sizes for optimal orbital wall reconstruction. It is difficult to design an orbital implant that exactly matches the shape and surface of a blowout fracture site due to the unique 3D structure of the orbit. The traditional surgical method is to visually inspect the fracture site and use eye measurements to cut a two-dimensional orbital implant that corresponds to the anatomical structure of the fracture site. However, implants that do not fit the anatomical structure of a fracture site well can cause complications such as enophthalmos, diplopia and displacement of the implant.

Implantation of Customized, Preshaped Implant for Orbital Fractures with the Aid of Three-dimensional Printing

Orbital floor fractures alone or in conjunction with other facial skeletal fractures are the most commonly encountered midfacial fractures. The technological advances in 3-dimensional (3D) printing allow the physical prototyping of 3D models, so creates an accurate representation of the patient's specific anatomy. A 56-year-old Caucasian man with severe hypoglobus and enophthalmos with an extensive blowout fracture was scheduled for reconstruction. First, 3D physical models were created based on the computed tomography scan datasets from patient. Then, this model was used as templates for preoperative trimming the implant. Surgical reconstruction with the aid of pre-shaped, customized prosthesis based on 3D anatomical model resulted in significant esthetic and clinical improvement. It is possible to build anatomical models on the basis of computed tomography scan datasets. It is relatively inexpensive and can be used in the repair of complex orbital floor fractures.