Accuracy of treatment planning based on stereolithography in computer assisted surgerya)

Vascular 3D Printing with a Novel Biological Tissue Mimicking Resin for Patient-Specific Procedure Simulations in Interventional Radiology: a Feasibility Study

Three-dimensional (3D) printing of vascular structures is of special interest for procedure simulations in Interventional Radiology, but remains due to the complexity of the vascular system and the lack of biological tissue mimicking 3D printing materials a technical challenge. In this study, the technical feasibility, accuracy, and usability of a recently introduced silicone-like resin were evaluated for endovascular procedure simulations and technically compared to a commonly used standard clear resin. Fifty-four vascular models based on twenty-seven consecutive embolization cases were fabricated from preinterventional CT scans and each model was checked for printing success and accuracy by CT-scanning and digital comparison to its original CT data. Median deltas (Δ) of luminal diameters were 0.35 mm for clear and 0.32 mm for flexible resin (216 measurements in total) with no significant differences (p > 0.05). Printing success was 85.2% for standard clear and 81.5% for the novel flexible resin. In conclusion, vascular 3D printing with silicone-like flexible resin was technically feasible and highly accurate. This is the first and largest consecutive case series of 3D-printed embolizations with a novel biological tissue mimicking material and is a promising next step in patient-specific procedure simulations in Interventional Radiology.

Three-Dimensional Technology Applications in Maxillofacial Reconstructive Surgery: Current Surgical Implications

Defects in the oral and maxillofacial (OMF) complex may lead to functional and esthetic impairment, aspiration, speech difficulty, and reduced quality of life. Reconstruction of such defects is considered one of the most challenging procedures in head and neck surgery. Transfer of different auto-grafts is still considered as the “gold standard” of regenerative and reconstructive procedures for OMF defects. However, harvesting of these grafts can lead to many complications including donor-site morbidity, extending of surgical time, incomplete healing of the donor site and others. Three-dimensional (3D) printing technology is an innovative technique that allows the fabrication of personalized implants and scaffolds that fit the precise anatomy of an individual’s defect and, therefore, has attracted significant attention during the last few decades, especially among head and neck surgeons. Here we discuss the most relevant applications of the 3D printing technology in the oral and maxillofacial surgery field. We further show different clinical examples of patients who were treated at our institute using the 3D technology and discuss the indications, different technologies, complications, and their clinical outcomes. We demonstrate that 3D technology may provide a powerful tool used for reconstruction of various OMF defects, enabling optimal clinical results in the suitable cases.

Influence of processing parameters on mechanical properties of a 3D-printed trabecular bone microstructure

Natural bone microstructure has shown to be the most efficient choice for the bone scaffold design. However, there are several process parameters involved in the generation of a microCT-based 3D-printed (3DP) bone. In this study, the effect of selected parameters on the reproducibility of mechanical properties of a 3DP trabecular bone structure is investigated. MicroCT images of a distal radial sample were used to reconstruct a 3D ROI of trabecular bone. Nine tensile tests on bulk material and 54 compression tests on 8.2 mm cubic samples were performed (9 cases × 6 specimens/case). The effect of input-image resolution, STL mesh decimation, boundary condition, support material, and repetition parameters on the weight, elastic modulus, and strength were studied. The elastic modulus and the strength of bulk material showed consistent results (CV% = 9 and 6%, respectively). The weight, elastic modulus, and strength of the cubic samples showed small intragroup variation (average CV% = 1.2, 9, and 5.5%, respectively). All studied parameters had a significant effect on the outcome variables with less effect on the weight. Utmost care to every step of the 3DP process and involved parameters is required to be able to reach the desired mechanical properties in the final printed specimen. © 2019 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:38-47, 2020.

Robot-assisted procedures in pediatric neurosurgery

OBJECTIVE

During the last 3 decades, robotic technology has rapidly spread across several surgical fields due to the continuous evolution of its versatility, stability, dexterity, and haptic properties. Neurosurgery pioneered the development of robotics, with the aim of improving the quality of several procedures requiring a high degree of accuracy and safety. Moreover, robot-guided approaches are of special interest in pediatric patients, who often have altered anatomy and challenging relationships between the diseased and eloquent structures. Nevertheless, the use of robots has been rarely reported in children. In this work, the authors describe their experience using the ROSA device (Robotized Stereotactic Assistant) in the neurosurgical management of a pediatric population.

METHODS

Between 2011 and 2016, 116 children underwent ROSA-assisted procedures for a variety of diseases (epilepsy, brain tumors, intra- or extraventricular and tumor cysts, obstructive hydrocephalus, and movement and behavioral disorders). Each patient received accurate preoperative planning of optimal trajectories, intraoperative frameless registration, surgical treatment using specific instruments held by the robotic arm, and postoperative CT or MR imaging.

RESULTS

The authors performed 128 consecutive surgeries, including implantation of 386 electrodes for stereo-electroencephalography (36 procedures), neuroendoscopy (42 procedures), stereotactic biopsy (26 procedures), pallidotomy (12 procedures), shunt placement (6 procedures), deep brain stimulation procedures (3 procedures), and stereotactic cyst aspiration (3 procedures). For each procedure, the authors analyzed and discussed accuracy, timing, and complications.

CONCLUSIONS

To the best their knowledge, the authors present the largest reported series of pediatric neurosurgical cases assisted by robotic support. The ROSA system provided improved safety and feasibility of minimally invasive approaches, thus optimizing the surgical result, while minimizing postoperative morbidity.

Customized Orbital Wall Reconstruction Using Three-Dimensionally Printed Rapid Prototype Model in Patients With Orbital Wall Fracture

BACKGROUND

It is difficult to restore original orbital contours because of their complex 3-dimensional structure. Moreover, slight implant malpositioning can result in enophthalmos or other complications. The authors describe our experience of using individualized prebent titanium-Medpor mesh implants and stereolithographic modeling in a series of patients who underwent orbital wall reconstruction.

METHODS

A consecutive series of 104 patients with orbital fractures received computer simulation-designed prebent titanium-Medpor mesh implants insertion. Preoperative computed tomography (CT) data were processed for each patient, and a rapid prototyping (RP) model was produced. The uninjured side was concurrently mirrored and superimposed onto the traumatized side to create a mirror image of the RP model. The authors fabricated the titanium-Medpor implants to intraoperatively reconstruct the 3-dimensional orbital structure. The prefabricated titanium-Medpor implants were inserted into the defective orbital wall and fixed. Postoperative CT images were immediately taken to evaluate the reconstructed contours and compare the preoperative and postoperative intraorbital volumes.

RESULTS

All reconstructions were successful without postoperative complications. The implants were correctly positioned in the sagittal, axial, and coronal planes relative to the original orbital contours. The mean preoperative intraorbital volumes of the uninjured and traumatized sides were 21.39 ± 1.93 and 23.17 ± 2.00 cm, respectively, and the postoperative mean intraorbital volume was 20.74 ± 2.07 cm.

CONCLUSIONS

Orbital reconstruction can be optimized using individually manufactured rapid prototype skull model and premolded synthetic scaffold by computer-aid of mirroring-reconstruction of 3-dimensional images and 3-dimensional printing techniques.

Orbital Osteoblastoma: Technical Innovations in Resection and Reconstruction Using Virtual Surgery Simulation

Osteoblastoma is a benign tumor of bone, representing less than 1% of bone tumors. Craniomaxillofacial localizations account for up to 15% of the total and frequently involve the posterior mandible. Endo-orbital localization is very rare, with most occurring in young patients. Very few of these tumors become malignant. Orbital localization requires radical removal of the tumor followed by careful surgical reconstruction of the orbit to avoid subsequent aesthetic or functional problems. Here, we present a clinical case of this condition and describe a surgical protocol that uses and integrates state-of-the art technologies to achieve orbital reconstruction.

Three-Dimensional Printing: Basic Principles and Applications in Medicine and Radiology

The advent of three-dimensional printing (3DP) technology has enabled the creation of a tangible and complex 3D object that goes beyond a simple 3D-shaded visualization on a flat monitor. Since the early 2000s, 3DP machines have been used only in hard tissue applications. Recently developed multi-materials for 3DP have been used extensively for a variety of medical applications, such as personalized surgical planning and guidance, customized implants, biomedical research, and preclinical education. In this review article, we discuss the 3D reconstruction process, touching on medical imaging, and various 3DP systems applicable to medicine. In addition, the 3DP medical applications using multi-materials are introduced, as well as our recent results.

Clinical application of three-dimensional printing technology in craniofacial plastic surgery

Three-dimensional (3D) printing has been particularly widely adopted in medical fields. Application of the 3D printing technique has even been extended to bio-cell printing for 3D tissue/organ development, the creation of scaffolds for tissue engineering, and actual clinical application for various medical parts. Of various medical fields, craniofacial plastic surgery is one of areas that pioneered the use of the 3D printing concept. Rapid prototype technology was introduced in the 1990s to medicine via computer-aided design, computer-aided manufacturing. To investigate the current status of 3D printing technology and its clinical application, a systematic review of the literature was conducted. In addition, the benefits and possibilities of the clinical application of 3D printing in craniofacial surgery are reviewed, based on personal experiences with more than 500 craniofacial cases conducted using 3D printing tactile prototype models.

In vivo measurement of the frame-based application accuracy of the Neuromate neurosurgical robot

OBJECT

The application accuracy of the Neuromate neurosurgical robot has been validated in vitro but has not been evaluated in vivo for deep brain stimulation (DBS) electrode implantations. The authors conducted a study to evaluate this application accuracy in routine frame-based DBS procedures, with an independent system of measurement.

METHODS

The Euclidian distance was measured between the point theoretically targeted by the robot and the point actually reached, based on their respective stereotactic coordinates. The coordinates of the theoretical target were given by the robot's dedicated targeting software. The coordinates of the point actually reached were recalculated using the Stereoplan localizer system. This experiment was performed in vitro, with the frame fixed in the robot space without a patient, for 21 points spatially distributed. The in vivo accuracy was then measured in 30 basal ganglia targets in 17 consecutive patients undergoing DBS for movement disorders.

RESULTS

The mean in vitro application accuracy was 0.44 ± 0.23 mm. The maximal localization error was 1.0 mm. The mean (± SD) in vivo application accuracy was 0.86 ± 0.32 mm (Δx = 0.37 ± 0.34 mm, Δy = 0.32 ± 0.24 mm, Δz = 0.58 ± 0.31 mm). The maximal error was 1.55 mm.

CONCLUSIONS

The in vivo application accuracy of the Neuromate neurosurgical robot, measured with a system independent from the robot, in frame-based DBS procedures was better than 1 mm. This accuracy is at least similar to the accuracy of stereotactic frame arms and is compatible with the accuracy required in DBS procedures.

Use of 3-dimensional stereolithographic polymer models for heterotopic ossification surgical excision

Heterotopic ossification is a known complication of traumatic injuries. To minimize iatrogenic complications during excision, an understanding of anatomic relationships is essential. Current imaging modalities, such as computed tomography and plain radiographs, are limited to providing a 2-dimensional representation of a 3-dimensional problem. This study describes the benefits of 3-dimensional stereolithography in the perioperative management of symptomatic heterotopic ossification using models were that were fabricated based on high-resolution computed tomography scans. The models facilitated heterotopic ossification excision through frequent intraoperative reference, allowing the authors to avoid iatrogenic neurovascular injuries.

Pediatric Craniofacial Surgery: A Review for the Multidisciplinary Team

Pediatric craniofacial surgery is a specialty that grew dramatically in the 20th century and continues to evolve today. Out of the efforts to correct facial deformities encountered during World War II, the techniques of modern craniofacial surgery developed. An analysis of the relevant literature allowed the authors to explore this historical progression.

Current advances in technology, tissue engineering, and molecular biology have further refined pediatric craniofacial surgery. The development of distraction osteogenesis and the progressive study of craniosynostosis provide remarkable examples of this momentum. The growing study of genetics, biotechnology, the influence of growth factors, and stem cell research provide additional avenues of innovation for the future. The following article is intended to reveal a greater understanding of pediatric craniofacial surgery by examining the past, present, and possible future direction. It is intended both for the surgeon, as well as for the nonsurgical individual specialists vital to the multidisciplinary craniofacial team.

Pre-operative planning for mandibular reconstruction - a full digital planning workflow resulting in a patient specific reconstruction

Objectives

Reconstruction of large mandiblular defects following ablative oncologic surgery could be done by using vascularized bone transfer or, more often, primarily with simultaneous or delayed bone grafting, using load bearing reconstruction plates. Bending of these reconstruction plates is typically directed along the outer contour of the original mandible. Simultaneously or in a second operation vascularized or non-vascularized bone is fixed to the reconstruction plate. However, the prosthodontic-driven backward planning to ease bony reconstruction of the mandible in terms of dental rehabilitation using implant-retained overdentures might be an eligible solution. The purpose of this work was to develop, establish and clinically evaluate a novel 3D planning procedure for mandibular reconstruction.

Materials and methods

Three patients with tumors involving the mandible, which included squamous cell carcinoma in the floor of the mouth and keratocystic odontogenic tumor, were treated surgically by hemimandibulectomy.

Results

In primary alloplastic mandible reconstruction, shape and size of the reconstruction plate could be predefined and prebent prior to surgery.

Clinical relevance

This study provides modern treatment strategies for mandibular reconstruction.

Mirror imaging and preshaped titanium plates in the treatment of unilateral malar and zygomatic arch fractures

OBJECTIVE

The aim of this study is to discuss the application of mirror imaging and preshaped titanium plates in the treatment of unilateral malar and zygomatic arch fractures.

STUDY DESIGN

Four patients with unilateral malar and zygomatic arch fractures were included in this study. All patients underwent preoperative CT scan. CT data were processed with Surgicase. Two 3D skull models were reconstructed using a rapid prototyping device. The first model was the original model obtained from CT scanning; the other model was obtained by mirroring the unaffected side onto the fractured side. Simulation surgery was performed on the first model. For the second model, titanium plates were shaped in advance and a resinous guide plate was created to guide surgical reduction. When using the resinous guide plates, 4 patients' fractures were reduced and fixed with preshaped titanium plates. The pre- and postoperative displacement of zygomatic markers were analyzed in Surgicase.

RESULTS

According to the measurement of fracture displacements, the facial asymmetry of all 4 patients was greatly improved at the 1-month follow-up.

CONCLUSIONS

Mirror imaging and preshaped titanium plates are viable choices for the treatment of unilateral malar and zygomatic arch fractures. Combined use of these techniques can improve facial symmetry.

Use of 3-d stereolithographic models in oral and maxillofacial surgery

OBJECTIVE

To assess the feasibility of the use of 3-dimensional (3-D) stereolithographic (SLA) technology in complex maxillofacial reconstructive surgery.

MATERIALS AND METHODS

3-D SLA technology was used in the treatment planning of complex maxillofacial procedures performed by the Department of Oral and Maxillofacial Surgery at Boston University. Specialized 3-D models were ordered and utilized for surgical treatment of a variety of indications including trauma surgery, temporomandibular joint surgery, orthognathic surgery, secondary correction of facial and skull deformities, and extensive jaw pathology. This technology was also used in one patient for jaw reconstruction using novel bone and tissue engineering techniques.

RESULTS

The use of 3-D models in Oral and Maxillofacial Surgery significantly improved predictability of clinical outcomes when compared to similar treatments without its use. Total operating time was reduced which had the benefit of decreasing the duration of general anesthesia and reducing wound exposure time. They allowed for assessment of extensive traumatic and pathologic defects in three-dimensions prior to surgical reconstruction. The models were also useful in the design and fabrication of custom prostheses, sizing of bone grafts and allowed for manufacturing of scaffolds for bone regeneration.

CONCLUSIONS

3-D SLA models can be very effectively used in oral and maxillofacial surgery for multiple indications and diverse clinical scenarios. Successful incorporation of this technology for jaw bone regeneration using tissue engineering techniques offers exciting new prospects for the future.

Design and fabrication of phantoms using stereolithography for small-animal imaging systems

PURPOSE

We have investigated a new technology for fabricating phantoms with fine details for use in small-animal imaging.

PROCEDURES

We used a high-resolution, 3-D stereolithography (SL) system to produce performance-evaluation phantoms such as cold-rod Derenzo, hot-channel Derenzo, and Defrise phantoms. SL performance was estimated by measuring the dimensions of many structures using a microscope. We also evaluated the degree of water absorption by two different SL resins, Somos 11120 and Accura 40, after curing.

RESULTS

The average bias and precision of the cold-rod structures over the size range 0.5 to 1.0 mm, were -0.4% and 1.74%, respectively. The water absorption study showed that Somos 11120 is a more suitable material for nuclear medicine applications.

CONCLUSION

We have demonstrated that SL is a robust and accurate method for fabrication of phantoms for small-animal imaging systems.