What are the limitations of the non-patient-specific implant in titanium reconstruction of the orbit?

Patient-specific implants made of 3D printed bioresorbable polymers at the point-of-care: material, technology, and scope of surgical application

BACKGROUND

Bioresorbable patient-specific additive-manufactured bone grafts, meshes, and plates are emerging as a promising alternative that can overcome the challenges associated with conventional off-the-shelf implants. The fabrication of patient-specific implants (PSIs) directly at the point-of-care (POC), such as hospitals, clinics, and surgical centers, allows for more flexible, faster, and more efficient processes, reducing the need for outsourcing to external manufacturers. We want to emphasize the potential advantages of producing bioresorbable polymer implants for cranio-maxillofacial surgery at the POC by highlighting its surgical applications, benefits, and limitations.

METHODS

This study describes the workflow of designing and fabricating degradable polymeric PSIs using three-dimensional (3D) printing technology. The cortical bone was segmented from the patient's computed tomography data using Materialise Mimics software, and the PSIs were designed created using Geomagic Freeform and nTopology software. The implants were finally printed via Arburg Plastic Freeforming (APF) of medical-grade poly (L-lactide-co-D, L-lactide) with 30% β-tricalcium phosphate and evaluated for fit.

RESULTS

3D printed implants using APF technology showed surfaces with highly uniform and well-connected droplets with minimal gap formation between the printed paths. For the plates and meshes, a wall thickness down to 0.8 mm could be achieved. In this study, we successfully printed plates for osteosynthesis, implants for orbital floor fractures, meshes for alveolar bone regeneration, and bone scaffolds with interconnected channels.

CONCLUSIONS

This study shows the feasibility of using 3D printing to create degradable polymeric PSIs seamlessly integrated into virtual surgical planning workflows. Implementing POC 3D printing of biodegradable PSI can potentially improve therapeutic outcomes, but regulatory compliance must be addressed.

Applications of Preoperative and Intraoperative Technologies for Complex Primary and Secondary Facial Trauma Reconstruction

This article provides a review of the current technologies available in the preoperative and intraoperative management of complex and secondary maxillofacial trauma reconstruction. These patients present a unique challenge for which the advancement of imaging technologies, patient-specific modeling and implants, and intraoperative imaging and navigation can play an important role to improve their post-treatment outcomes.

Current Guidelines and Opinions in the Management of Orbital Floor Fractures

Orbital floor fractures are a common manifestation of facial trauma that is encountered by ophthalmology, otolaryngology, and oral maxillofacial specialists. Surgical intervention is required emergently in cases of tissue entrapment and less urgently in cases of presenting with persistent diplopia, enophthalmos greater than 2 mm, and/or fractures involving greater than 50% of the orbital floor. Surgical management is a debated topic with differing opinions among surgeons regarding timing of repair, type of implant, and surgical approach.

Is the Pre-Shaping of an Orbital Implant on a Patient-Specific 3D-Printed Model Advantageous Compared to Conventional Free-Hand Shaping? A Systematic Review and Meta-Analysis

This study aimed to perform a systematic review and meta-analysis to compare pre-shaped implants on a patient-specific 3D-printed (3DP) model to manual free-hand shaping (MFS) for orbital wall reconstruction. The PRISMA protocol was followed in this study, and the review was registered in the PROSPERO database (CRD42021261594). A search was conducted in MEDLINE (PubMed), Embase, Cochrane Library, Clinicaltrials.gov, Google Scholar, and the grey literature. Ten articles were included, and six outcomes were analyzed. In total, 281 patients were in the 3DP group and 283 were in the MFS group. The studies had an overall high risk of bias. 3DP models resulted in a better accuracy of fit, anatomical angle reproduction, and defect area coverage. The correction of orbital volume was also superior with statistical significance. There was a higher percentage of the correction of enophthalmos and diplopia in the 3DP group. Intraoperative bleeding and hospital stay were reduced in the 3DP group. The meta-analysis of operative time showed a reduction in the average operative time by 23.58 min (95% CI: -43.98 to -3.19), which was statistically significant (t(6) = -2.8299, p = 0.0300). The 3DP models appear advantageous for an accurate orbital wall reconstruction, with fewer complications than those for conventional free-hand-shaped implants.

Two-Dimensional Post-Traumatic Measurements of Orbital Floor Blowout Fractures Underestimate Defect Sizes Compared to Three-Dimensional Approaches

Orbital floor fractures represent a common fracture type of the midface and are standardly diagnosed clinically as well as radiologically using linear measurement methods. The aim of this study was to evaluate the accuracy of diagnostic measurements of isolated orbital floor fractures based on two-dimensional (2D) and three-dimensional (3D) measurement techniques. A cohort of 177 patients was retrospectively and multi-centrically evaluated after surgical treatment of an orbital floor fracture between 2010 and 2020. In addition to 2D and 3D measurements of the fracture area, further fracture-related parameters were investigated. Calculated fracture areas using the 2D measurement technique revealed an average area of 287.59 mm², whereas the 3D measurement showed fracture areas with a significantly larger average value of 374.16 mm² (p < 0.001). On average, the 3D measurements were 1.53-fold larger compared to the 2D measurements. This was observed in 145 patients, whereas only 32 patients showed smaller values in the 3D-based approach. However, the process duration of the 3D measurement took approximately twice as long as the 2D-based procedure. Nonetheless, 3D-based measurement of orbital floor defects provides a more accurate estimation of the fracture area than the 2D-based procedure and can be helpful in determining the indication and planning the surgical procedure.

Plasma Electrolytic Polished Patient-Specific Orbital Implants in Clinical Use-A Technical Note

This technical note describes the technique of plasma electrolytic polishing on orbital patient-specific implants and demonstrates clinical handling and use by the insertion of a plasma electrolytic polished orbital implant into a patient.

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.

Personalized Medicine Workflow in Post-Traumatic Orbital Reconstruction

Restoration of the orbit is the first and most predictable step in the surgical treatment of orbital fractures. Orbital reconstruction is keyhole surgery performed in a confined space. A technology-supported workflow called computer-assisted surgery (CAS) has become the standard for complex orbital traumatology in many hospitals. CAS technology has catalyzed the incorporation of personalized medicine in orbital reconstruction. The complete workflow consists of diagnostics, planning, surgery and evaluation. Advanced diagnostics and virtual surgical planning are techniques utilized in the preoperative phase to optimally prepare for surgery and adapt the treatment to the patient. Further personalization of the treatment is possible if reconstruction is performed with a patient-specific implant and several design options are available to tailor the implant to individual needs. Intraoperatively, visual appraisal is used to assess the obtained implant position. Surgical navigation, intraoperative imaging, and specific PSI design options are able to enhance feedback in the CAS workflow. Evaluation of the surgical result can be performed both qualitatively and quantitatively. Throughout the entire workflow, the concepts of CAS and personalized medicine are intertwined. A combination of the techniques may be applied in order to achieve the most optimal clinical outcome. The goal of this article is to provide a complete overview of the workflow for post-traumatic orbital reconstruction, with an in-depth description of the available personalization and CAS options.

"6 Anatomical Landmarks" Technique for Satisfactory Free-Hand Orbital Reconstruction With Standard Preformed Titanium Mesh

Study Design

Retrospective study.

Objective

Resolution of clinical signs and symptoms following orbital fractures depends on the accurate restoration of the orbital volume. Computer-Assisted procedures and Patient Specific Implants represent modern solutions, but they require additional resources. A more reproducible option is the use of standard preformed titanium meshes, widely available and cheaper; with their use quality of results is proportional to the accuracy with which they are positioned. This work identifies 6 reproducible and constant anatomical landmarks, as an intraoperative guide for the precise positioning of titanium preformed meshes.

Methods

90 patients treated at the Maxillofacial Surgery Department, Niguarda Trauma Center, Milan, for unilateral orbital reconstruction (January 2012 to December 2018), were studied. In all cases reconstruction was performed respecting the 6 proposed anatomical landmarks. The outcomes analyzed are: post-operative CT adherence to the 6 anatomical markers and symmetry achieved respect to controlateral orbit; number/year of re-interventions and duration of surgery; resolution of clinical defects (at least 12-months follow-up); incidence of complications.

Results

Satisfactory results were obtained in terms of restoration of orbital size, shape and volume. Clinical defects early recovered with a low incidence of complications and re-interventions. Operating times and radiological accuracy have shown a progressive improvement during years of application of this technique.

Conclusions

The proposed "6 anatomical landmarks" is an easy free-hand technique that allows everyone to obtain high levels of reconstructive accuracy and it should be a skill of all surgeons who deal with orbital reconstruction in daily clinical activity.

A Novel Patient-specific Titanium Mesh Implant Design for Reconstruction of Complex Orbital Fracture

Complex orbital fractures, including orbital rims and walls, require precise reconstruction. A titanium-based patient-specific implant (PSI) benefits over other implants when challenged with narrow surgical space and designable implant fixation point.

Customized and Navigated Primary Orbital Fracture Reconstruction: Computerized Operation Neuronavigated Surgery Orbital Recent Trauma (CONSORT) Protocol

ABSTRACT

Combined orbital medial wall and floor fractures and large isolated orbital floor fractures commonly require surgical treatment due to the high probability of diplopia and enophthalmos. Primary reconstruction of these orbital fractures requires a high-level surgeon with a great amount of technical surgical skill. The use of novel technology can greatly improve the accuracy of reconstruction and achieve satisfactory clinical outcomes. Hence, the authors aimed to present our findings and overall experience with respect to extensive floor and medial wall orbital fracture reconstruction according to the Computerized Operation Neuronavigated Surgery Orbital Recent Trauma (CONSORT) protocol, a workflow designed for the primary reconstruction of orbital fractures with customized mesh and intraoperative navigation. A total of 25 consecutively presenting patients presenting with unilateral extensive orbital floor fractures and orbital floor and medial wall fractures were treated following the CONSORT workflow from January 2017 to March 2020. Fractures were surgically treated with a customized implant and intraoperative navigation. Patients underwent surgery within 14 days of the trauma injury. Preoperative and postoperative functional and aesthetic outcomes are described herein. All fractures were successfully reconstructed. Postoperatively, all 19 patients with preoperative diplopia reported the resolution of diplopia. Enophthalmos resolved in 18/20 cases. No patients had major complications during follow-up. Thus, the authors conclude that the CONSORT protocol introduced by the authors is an adaptable and reliable workflow for the early treatment of orbital fractures and can clearly optimize functional and aesthetic outcomes, reduce costs and intensive time commitments, and make customized and navigated surgery more available for institutions.

Do Racial Differences in Orbital Volume Influence the Reconstruction of Orbital Trauma

PURPOSE

Successful orbital reconstruction relies on an accurate restoration of orbital volume (OV). The purpose of this study was to determine if the OV of African American (AA) subjects differs from that of Caucasian subjects.

METHODS

The authors implemented a retrospective observational study of successive subjects who received a maxillofacial computed tomography (CT) scan at a level I trauma center between 2017 and 2020. The primary predictor variable was race (AA/Caucasian). The primary outcome variable was orbital volume. Two independent examiners calculated OV with an open access OsiriX MD software version 10.0.5 (Pixmeo, Switzerland). Inter-rater reliability was calculated. Differences between races, genders, and sides were tested using independent samples t test with a significance of P < .05.

RESULTS

Sixty subjects (120 orbits) were included in the study. The mean age was 36.7 (SD ± 13.2) years with a range of 22 to 78 years. Gender distribution was equal with 30 male (50%) and 30 female (50%) subjects. Inter-examiner reliability was 0.973. The mean OV of AA and Caucasians was 22.38 and 23.23 cm³, respectively (P = .07). The mean OV of AA and Caucasian males was 23.92, and 24.17cm³, respectively (P = .71). The mean OV in AA and Caucasian females was 20.84 and 22.28cm³, respectively (P = .013).

CONCLUSIONS

African-American female subjects appear to have a smaller OV when compared with Caucasians which may influence orbital reconstruction. Laterality does not appear to be associated with any differences in OV.

Technical Note on Three- and Four-Wall Orbital Reconstructions with Patient-Specific Implants

ABSTRACT

Orbital reconstruction is one of the most complex procedures in maxillofacial surgery. It becomes even more complex when all references to the original anatomy are lost. The purpose of this article is to provide an overview of techniques for complex three- and four-wall orbital reconstructions. Preoperative virtual surgical planning is essential when considering different reconstruction possibilities. The considerations that may lead to different approaches are described, and the advantages and drawbacks of each technique are evaluated. It is recommended to reconstruct solitary three-wall or four-wall orbital defects with multiple patient-specific implants. Optimizations of this treatment protocol are suggested, and their effects on predictability are demonstrated in a case presentation of a four-wall defect reconstruction with multiple patient-specific implants.

Critical appraisal of patient-specific implants for secondary post-traumatic orbital reconstruction

In orbital reconstruction, a patient-specific implant (PSI) may provide accurate reconstruction in complex cases, since the design can be tailored to the anatomy. Several design options may be embedded, for ease of positioning and precision of reconstruction. This study describes a cohort of 22 patients treated for secondary orbital reconstruction with a PSI; one patient received two PSI. The preoperative clinical characteristics and implant design options used are presented. When compared to preoperative characteristics, the postoperative clinical outcomes showed significant improvements in terms of enophthalmos (P < 0.001), diplopia (P < 0.001), and hypoglobus (P = 0.002). The implant position in all previous reconstructions was considered inadequate. Quantitative analysis after PSI reconstruction showed accurate positioning of the implant, with small median and 90th percentile deviations (roll: median 1.3°, 90th percentile 4.6°; pitch: median 1.4°, 90th percentile 3.9°; yaw: median 1.0°, 90th percentile 4.4°; translation: median 1.4 mm, 90th percentile 2.7 mm). Rim support proved to be a significant predictor of roll and rim extension for yaw. No significant relationship between design options or PSI position and clinical outcomes could be established. The results of this study show the benefits of PSI for the clinical outcomes in a large cohort of secondary post-traumatic orbital reconstructions.

Intraosseous Venous Malformation of the Zygomatic Bone: Comparison between Virtual Surgical Planning and Standard Surgery with Review of the Literature

Intraosseous venous malformations affecting the zygomatic bone are infrequent. Primary reconstruction is usually accomplished with calvarial grafts, although the use of virtual surgical planning, cutting guides and patient-specific implants (PSI) have had a major development in recent years. A retrospective study was designed and implemented in patients diagnosed with intraosseous venous malformation during 2006–2021, and a review of the scientific literature was also performed to clarify diagnostic terms. Eight patients were treated, differentiating two groups according to the technique: four patients were treated through standard surgery with resection and primary reconstruction of the defect with calvarial graft, and four patients underwent resection and primary reconstruction through virtual surgical planning (VSP), cutting guides, STL models developed with CAD-CAM technology and PSI (titanium or Polyether-ether-ketone). In the group treated with standard surgery, 75% of the patients developed sequelae or morbidity associated with this technique. The operation time ranged from 175 min to 210 min (average 188.7 min), the length of hospital ranged from 4 days to 6 days (average 4.75 days) and the postoperative CT scan showed a defect surface coverage of 79.75%. The aesthetic results were “excellent” in 25% of the patients, “good” in 50% and “poor” in 25%. In the VSP group, 25% presented sequelae associated with surgical treatment. The operation time ranged from 99 min to 143 min (average 121 min), the length of hospital stay ranged from 1 to 2 days (average of 1.75 days) and 75% of the patients reported “excellent” results. Postoperative CT scan showed 100% coverage of the defect surface in the VSP group. The multi-stage implementation of virtual surgical planning with cutting guides, STL models and patient-specific implants increases the reconstructive accuracy in the treatment of patients diagnosed with intraosseous venous malformation of the zygomatic bone, reducing sequelae, operation time and average hospital stay, providing a better cover of the defect, and improving the precision of the reconstruction and the aesthetic results compared to standard technique.

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.

Going beyond the limitations of the non-patient-specific implant in titanium reconstruction of the orbit

Reconstruction of post traumatic orbital defects has undergone a stepwise evolution following developments in reconstructive materials and surgical techniques. Advances in communication between surgical teams and design technicians have allowed provision of bespoke surgical plates with a high degree of accuracy and surgical relevance in an appropriate timeframe. We present a case series of 41 consecutive patients treated in London and BernBern Switzer between March 2019 and September 2020 with extensive defects reconstructed with patient specific orbital plates. Complexity of fracture was risk adjusted using the Jaquiery scale with one patient (J3), 14 patients (J4), and 26 Patients (J5). Outcome was assessed by accuracy of fit at the surgical margins and was 94.5%. The study group was statistically tested against a previous series by the same group and was statistically different with respect to the case complexity (p<0.001) and accuracy of fit (p<0.001) (Fisher's exact test). Complications included the removal on one plate due to patient choice, with perfect surgical position and resolving diplopia. Only one plate articulation was poor, this mitigated by the size of the defect and the orbital soft tissue swelling which prohibited seating the implant. The patient remains well with acceptable function and satisfactory aesthetics. We present design considerations including the use two part plates, and surgical pearls to achieve predictable placement. We believe that the use of custom plates for reconstruction of Jaquiery 4 and 5 should be considered. We regard this technology as a game changer in surgical management of the complex high risk orbit.

Implant malposition and revision surgery in primary orbital fracture reconstructions

The aim of the study was to assess factors leading to revision surgery and implant position of primary orbital fracture reconstructions. A retrospective cohort included patients who underwent orbital floor and/or medial wall fracture reconstruction for recent trauma. Demographics, fracture type, surgery and implant-related variables, and postoperative implant position were analyzed. The overall revision surgery rate was 6.5% (15 of 232 surgeries). The rate was highest in combined midfacial fractures with rim involvement (14.0%), lower in zygomatico-orbital fractures (8.7%), and lowest in isolated blowout fractures (3.8%). Fracture type, orbital rim fixation and implant malposition predicted revision. The best positioning was achieved with patient-specific milled titanium implants (mtPSI) and resorbable materials, whereas the poorest with preformed three-dimensional titanium plates. Combined midfacial fractures with rim involvement in particular have a high risk for orbital revision surgery. Within the limitations of the present study, mtPSIs should be preferred in the reconstruction of primary orbital fractures if possible.

Development of an Automatic Robotic Procedure for Machining of Skull Prosthesis

The project presented in this paper develops within the field of automation in the medical-surgical sector. It aims at automating the process for the realization of prosthetic devices for the skull in cranioplasty, following a craniotomy intervention for brain tumor removal. The paper puts emphasis on the possibility to create the prosthetic device in run-time during the surgery, in order to ease the work that surgeons have to do during the operation. Generally, a skull prosthesis is realized before the day of the intervention, based on the plan of the medical operation, on the results of computed tomography, and through image processing software. However, after the surgery is performed, a non-negligible geometrical uncertainty can be found between the part of the skull actually removed and the cut planned during the preliminary analysis, so that the realized prosthesis (or even the skull, at worse) may need to be retouched. This paper demonstrates the possibility to introduce a fully automated process in a hospital environment, to manufacture in runtime the prosthetic operculum, relying on the actual geometry of the incision of the skull detected during the intervention. By processing a 3D scan of the skull after the craniectomy, a digital model of the prosthesis can be created and then used as an input to generate the code to be run by a robotic system in charge of the workpiece machining. Focusing on this second step, i.e., the manufacturing process, the work describes the way the dimensions of the raw material block are automatically selected, and the way robot trajectories for milling operation are automatically generated. Experimental validation demonstrates the possibility to complete the prosthesis within the surgery time, thus increasing the accuracy of the produced prosthesis and consequently reducing the time needed to complete the operation.