Three dimensional reconstruction of late post traumatic orbital wall defects by customized implants using CAD-CAM, 3D stereolithographic models: A case report

Late patient-fitted total orbital reconstruction for facial gunshot wound sequelae

Late reconstructions of gunshot wounds (GSWs) in the orbital area are a true challenge to the oral and maxillofacial surgeon. Usually, the wall defects are large in size and commonly present loss of orbital volume, which can cause ocular dystopia. The only exceptions are when there is an explosion of the orbital walls-that is, blow-out fractures. We encountered a patient with a two-year sequelae after GSW in the face that caused the destructed orbit to have a 2.5 bigger size than the contralateral orbit, requiring meticulous planning of a patient-specific implant (PSI) to correctly reconstruct the orbit volume and bone projection. The PSI was developed using titanium and it had three pieces that could reconstruct all four walls of the orbit. After surgery, the patient regained orbital volume and malar projection, allowing him to benefit from facial symmetry. The PSI can be used to reconstruct all the orbital walls in cases of complex bone defects.

3D Bioprinting at the Frontier of Regenerative Medicine, Pharmaceutical, and Food Industries

3D printing technology has emerged as a key driver behind an ongoing paradigm shift in the production process of various industrial domains. The integration of 3D printing into tissue engineering, by utilizing life cells which are encapsulated in specific natural or synthetic biomaterials (e.g., hydrogels) as bioinks, is paving the way toward devising many innovating solutions for key biomedical and healthcare challenges and heralds' new frontiers in medicine, pharmaceutical, and food industries. Here, we present a synthesis of the available 3D bioprinting technology from what is found and what has been achieved in various applications and discussed the capabilities and limitations encountered in this technology.

The Management of Orbital Roof Fractures and Defects: A Review

PURPOSE

To explore the anatomy, etiopathogenesis, diagnosis and classification, current evidence on intervention and the surgical management of orbital roof fractures and defects (ORFD) for oculoplastic surgeons presented with such cases.

METHODS

A review of the current literature through the MEDLINE database using the following search terms: "orbital roof fracture (+treatment/management)," "orbital roof defect (+treatment/management)," "orbital roof erosion (+treatment/management)," "orbital roof repair," "orbital roof," "orbital fracture," "pediatric orbital roof (defect/fracture/erosion)," "orbital anatomy," and "orbital roof anatomy" was conducted. As relatively little has been published on this topic, inclusion criteria were broad and peer-reviewed articles judged to be of clinical importance, relevant to the aims of this review, were included. Non-English abstracts were also included if relevant. Year of publication was not a strict exclusion criterion, and older articles were judged for their suitability based on clinical importance and relevance to current practice. Additional references were obtained from citations in key articles and recommendations from the coauthors based on their areas of expertise.

RESULTS

The etiopathogenesis of ORFD varies. Classification systems have been formulated to guide management decisions and can range from conservative management to complex neurosurgery. Eyelid approaches have also been described. This review provides a summary of the evidence for each and a management framework oculoplastic surgeons can use when presented with ORFD.

CONCLUSION

Oculoplastic surgeons can be involved, either alone or as part of a multidisciplinary team, in the management of ORFD, and for some, conduct orbital approach reconstructive surgery.

Quantitative analysis of regional specific pelvic symmetry

Understanding bilateral pelvic symmetry can be useful for analyzing complex pelvis anatomy and simplifying difficult procedures for pelvic fractures. This paper aims to quantify the degree of regional pelvic symmetry using computer-based methods. CT scans of 30 intact pelvises were digitized into 3D models and regions were defined: the ilium, acetabulum, pubis, and ischium. The right hemipelvis was aligned with the left, and deviations between the two models were quantified using method 1 (global registration) and method 2 (local registration). Symmetry was evaluated using the root mean square (RMS) of the deviations and the percentage of points within preset thresholds of ± 2 mm and ± 1 mm. The results showed that > 86% of points are within the ± 2 mm deviation threshold and average RMS are < 1.33 mm. For all regions, method 2 showed lower deviations than method 1. The pubis and ischium regions showed a large difference in symmetry between the two methods indicating high local symmetry, but a degree of global asymmetry. Conversely, the acetabular and iliac regions showed similar levels of symmetry with the two methods. When evaluated locally, the pelvic regions can be considered highly symmetric; the acetabulum is highly symmetric globally as well. These findings can be used in future studies to assess the feasibility of patient-specific implants using the mirrored contralateral hemipelvis as a template for unilateral pelvic fracture fixation. The left image shows the "cut planes" used to define four pelvic regions: the ilium, acetabulum, pubis, and ischium. The right image shows a deviation color map (DCM) used to quantify bilateral pelvic symmetry. The scale and color illustrate the degree of deviation of the left hemipelvis with the right hemipelvis with the units in millimeters (mm).

Orbital floor repair using patient specific osteoinductive implant made by stereolithography

The orbital floor (OF) is an anatomical location in the craniomaxillofacial (CMF) region known to be highly variable in shape and size. When fractured, implants commonly consisting of titanium meshes are customized by plying and crude hand-shaping. Nevertheless, more precise customized synthetic grafts are needed to meticulously reconstruct the patients' OF anatomy with better fidelity. As alternative to titanium mesh implants dedicated to OF repair, we propose a flexible patient-specific implant (PSI) made by stereolithography (SLA), offering a high degree of control over its geometry and architecture. The PSI is made of biodegradable poly(trimethylene carbonate) (PTMC) loaded with 40 wt % of hydroxyapatite (called Osteo-PTMC). In this work, we developed a complete work-flow for the additive manufacturing of PSIs to be used to repair the fractured OF, which is clinically relevant for individualized medicine. This work-flow consists of (i) the surgical planning, (ii) the design of virtual PSIs and (iii) their fabrication by SLA, (iv) the monitoring and (v) the biological evaluation in a preclinical large-animal model. We have found that once implanted, titanium meshes resulted in fibrous tissue encapsulation, whereas Osteo-PMTC resulted in rapid neovascularization and bone morphogenesis, both ectopically and in the OF region, and without the need of additional biotherapeutics such as bone morphogenic proteins. Our study supports the hypothesis that the composite osteoinductive Osteo-PTMC brings advantages compared to standard titanium mesh, by stimulating bone neoformation in the OF defects. PSIs made of Osteo-PTMC represent a significant advancement for patients whereby the anatomical characteristics of the OF defect restrict the utilization of traditional hand-shaped titanium mesh.

Restoration of the inferomedial orbital strut using a standardized three-dimensional printing implant

The inferomedial orbital strut (IOS) is the thin bony junction of the orbital medial wall and floor. Its fracture is common and leads to serious complications, including enophthalmos, globe dystopia and diplopia. However, anatomical restoration of the IOS is challenging owing to reduced structural support; sound anatomical background and accurate implants are therefore essential. The aim of the present study was to incorporate data from cadaveric orbit anatomy into three-dimensional (3D) printing technology and to reconstruct the complex orbital fracture elaborately. After averaging the data from computed tomography (CT) images of 100 adult cadavers, the dimensions of the IOS were extracted, and a tangent sphere was created using a computer-aided design program. The curves were compared with the CT data of 10 adult patients from the simulation test. Based on these data, a standardized 3D implant, 1.15 mm thick, was designed using polycaprolactone. The implant was placed in five patients with complex orbital fractures. The radius of the sphere in contact with the orbit, measuring 33.54 mm, was confirmed to be appropriate. A comparison between the normal side volume (V0) and the postoperative volume (V_post ) showed that they were statistically similar. Furthermore, a comparison between V0 and the preoperative volume (V_pre ), and V_post compared with V_pre also showed a statistically significant difference (P < 0.05). On follow-up, the preoperative ocular symptoms were resolved. The orbital data obtained from 100 cadavers provided standardized orbital anatomy, and 3D printed implants were created. The implants were anatomically accurate with regard to the orbital cavity and adequately covered the simulation model. The implant also showed satisfactory results when applied clinically in actual patients.

Investigation of pelvic symmetry using CAD software

Severe pelvic fractures often prove difficult for surgeons as they require patient-specific surgical treatment plans and customized equipment. Developing virtual patient-specific 3D pelvis models would ease the surgical planning process and enable development of custom fixation plates. This paper aims to examine pelvic symmetry to conclude whether the contralateral side may be used as a reference model for the fractured side of the pelvis. Fourteen subjects with intact pelvises were involved in this study. CT scans of the pelvises were converted to 3D models and the right sides of the pelvises were reflected and aligned with the left sides. A deviation analysis was then performed for each set of models and results showed that the average root mean square (RMS) of values was 1.14 ± 0.26 mm and the average percentage of points below a deviation threshold of ± 2 mm was 91.9 ± 5.55%. The deviation color maps (DCMs) showed that the largest deviations were on the non-articular surfaces. The volume and surface area of each model were also examined and showed no significant differences between left and right sides. These results indicate that the pelvis displays bilateral symmetry and this concept can be used to develop fully intact patient-specific 3D pelvis models for fracture reconstruction using the unfractured contralateral side. Graphical Abstract.

Repair of Orbital Post-Traumatic Wall Defects by Custom-Made TiNi Mesh Endografts

Repairs of orbital post-traumatic and extensive malignant defects remain a major surgical challenge, in view of follow-up outcomes. Incorrect surgical management of injured facial structures results in cosmetic, ophthalmic, and social aftereffects. A custom-made knitted TiNi-based mesh (KTNM) endograft was employed to overcome post-surgical complications and post-resected lesions of the orbital area. Preoperative high-resolution computed tomography (CT) imaging and CAD modelling were used to design the customized KTNM in each case. Twenty-five patients underwent surgery utilizing the suggested technique, from 2014 to 2019. In all documented cases, resolution of the ophthalmic malfunction was noted in the early period. Follow-up observation evidenced no relapsed enophthalmos, hypoglobus, or diplopia as late complications. The findings emanating from our clinical observations allow us to claim that the KTNM indicated a high level of biocompatibility. It is simply modified intraoperatively to attach any desired shape/size for implantation and can also be screw-fixed, providing a good supporting ability. The KTNM precisely renders orbitozygomatic outlines and orbital floor, thus recovering the anatomical structure, and is regarded as an attractive alternative to Ti-based meshes and plates. Additionally, we report one of the studied cases, where good functional and cosmetic outcomes have been achieved.

Current Biomedical Applications of 3D Printing and Additive Manufacturing

Additive manufacturing (AM) has emerged over the past four decades as a cost-effective, on-demand modality for fabrication of geometrically complex objects. The ability to design and print virtually any object shape using a diverse array of materials, such as metals, polymers, ceramics and bioinks, has allowed for the adoption of this technology for biomedical applications in both research and clinical settings. Current advancements in tissue engineering and regeneration, therapeutic delivery, medical device fabrication and operative management planning ensure that AM will continue to play an increasingly important role in the future of healthcare. In this review, we outline current biomedical applications of common AM techniques and materials.

Correction of Delayed Traumatic Enophthalmos Using Customized Orbital Implants

PURPOSE

To determine the relation between overcorrection of orbital volume and ocular projection in patients with orbital trauma.

MATERIALS AND METHODS

A prospective cohort study was performed of patients with enophthalmos as a side effect of orbital trauma. The sample included patients older than 18 years who required reconstruction using customized implants to treat enophthalmos with or without diplopia. The exclusion criteria were patients who had multiple or extended fractures and patients with amaurosis or a prosthetic eye. Orbital volumes were calculated and the position of the eyeball in the healthy and traumatized sockets was determined before and after installing the implant and the ratio between these variables was calculated. Two variables were identified: 1) orbital volume and 2) enophthalmos. Analysis of the estimator variables was performed, defining 3 groups: 1) healthy eye socket, 2) traumatized eye socket without implant, and 3) traumatized eye socket with implant. The Shapiro-Wilk test, paired t test, and linear regression analysis were performed. A P value less than .05 (95% confidence interval) indicated significant differences.

RESULTS

Of 294 patients who underwent orbital zygomatic complex reconstruction surgery, 13 required customized implants and only 5 met the inclusion criteria. The average volumetric variation in the groups of traumatized eye sockets with and without implants was statistically significant (P < .05), overcorrecting by an average of 4.2 cm³. The average enophthalmos variation in the groups of traumatized eye sockets with and without implants was statistically significant (P < .05), projecting the eyeball by an average 1.80 mm. The ratio between the average orbital volume and projection of the eyeball was determined to be 1:0.721 (correlation, 45.6%).

CONCLUSION

This study concluded that the eyeball is projected 0.7 mm for every 1 cm³ of volume added in customized orbital implants. However, additional clinical studies with larger samples should be conducted.