Optimizing Craniofacial Osteotomies: Applications of Haptic and Rapid Prototyping Technology

Use of 3D Printing Technology in Fracture Management: A Review and Case Series

SUMMARY

Three-dimensional (3D) offers exciting opportunities in medicine, particularly in orthopaedics. The boundaries of 3D printing are continuously being re-established and have paved the way for further innovations, including 3D bioprinting, custom printing refined methods, 4D bioprinting, and 5D printing potential. The quality of these applications have been steadily improving, increasing their widespread use among clinicians. This article provides a review of the current literature with a brief introduction to the process of additive manufacturing, 3D printing, and its applications in fracture care. We illustrate this technology with a case series of 3D printing used for correction of complex fractures/nonunion. Factors limiting the use of this technology, including cost, and potential solutions are discussed. Finally, we discuss 4D bioprinting and 5D printing and their potential role in fracture surgery.

Digital planning and individual implants for secondary reconstruction of midfacial deformities: A pilot study

Objective

To evaluate the feasibility and accuracy of implementing three‐dimensional virtual surgical planning (VSP) and subsequent transfer by additive manufactured tools in the secondary reconstruction of residual post‐traumatic deformities in the midface.

Methods

Patients after secondary reconstruction of post‐traumatic midfacial deformities were included in this case series. The metrical deviation between the virtually planned and postoperative position of patient‐specific implants (PSI) and bone segments was measured at corresponding reference points. Further information collected included demographic data, post‐traumatic symptoms, and type of transfer tools.

Results

Eight consecutive patients were enrolled in the study. In five patients, VSP with subsequent manufacturing of combined predrilling/osteotomy guides and PSI was performed. In three patients, osteotomy guides, repositioning guides, and individually prebent plates were used following VSP. The median distances between the virtually planned and the postoperative position of the PSI were 2.01 mm (n = 18) compared to a median distance concerning the bone segments of 3.05 mm (n = 12). In patients where PSI were used, the median displacement of the bone segments was lower (n = 7, median 2.77 mm) than in the group with prebent plates (n = 5, 3.28 mm).

Conclusion

This study demonstrated the feasibility of VSP and transfer by additive manufactured tools for the secondary reconstruction of complex residual post‐traumatic deformities in the midface. However, the median deviations observed in this case series were unexpectedly high. The use of navigational systems may further improve the level of accuracy.

To evaluate the feasibility and accuracy of implementing three‐dimensional virtual surgical planning (VSP) and subsequent transfer by additive manufactured tools in the secondary reconstruction of residual post‐traumatic deformities in the midface. This study demonstrated the feasibility of VSP and transfer by additive manufactured tools for the secondary reconstruction of complex residual post‐traumatic deformities in the midface. However, the median deviations observed in this case series were unexpectedly high. The use of navigational systems may further improve the level of accuracy.

Evaluation of 3D printing costs in surgery: a systematic review

OBJECTIVES

The use of three-dimensional (3D) printing in surgery is expanding and there is a focus on comprehensively evaluating the clinical impact of this technology. However, although additional costs are one of the main limitations to its use, little is known about its economic impact. The purpose of this systematic review is to identify the costs associated with its use and highlight the first quantitative data available.

METHODS

A systematic literature review was conducted in the PubMed and Embase databases and in the National Health Service Economic Evaluation Database (NHS EED) at the University of York. Studies that reported an assessment of the costs associated with the use of 3D printing for surgical application and published between 2009 and 2019, in English or French, were included.

RESULTS

Nine studies were included in our review. Nine types of costs were identified, the three main ones being printing material costs (n = 6), staff costs (n = 3), and operating room costs (n = 3). The printing cost ranged from less than U.S. dollars (USD) 1 to USD 146 (in USD 2019 values) depending on the criteria used to calculate this cost. Three studies evaluated the potential savings generated by the use of 3D printing technology in surgery, based on operating time reduction.

CONCLUSION

This literature review highlights the lack of reliable economic data on 3D printing technology. Nevertheless, this review makes it possible to identify expenditures or items that should be considered in order to carry out more robust studies.

Radiological Society of North America (RSNA) 3D printing Special Interest Group (SIG): guidelines for medical 3D printing and appropriateness for clinical scenarios

Medical three-dimensional (3D) printing has expanded dramatically over the past three decades with growth in both facility adoption and the variety of medical applications. Consideration for each step required to create accurate 3D printed models from medical imaging data impacts patient care and management. In this paper, a writing group representing the Radiological Society of North America Special Interest Group on 3D Printing (SIG) provides recommendations that have been vetted and voted on by the SIG active membership. This body of work includes appropriate clinical use of anatomic models 3D printed for diagnostic use in the care of patients with specific medical conditions. The recommendations provide guidance for approaches and tools in medical 3D printing, from image acquisition, segmentation of the desired anatomy intended for 3D printing, creation of a 3D-printable model, and post-processing of 3D printed anatomic models for patient care.

Current status of 3D printing in spine surgery

Three-dimensional printing (3DP) is one of the latest tools in the armamentarium of the modern spine surgeon. The yearning to be more precise and reliable whilst operating on the spine has led to an interest in this technology which has claimed to achieve these goals. 3D printing has been used pre-operatively for surgical planning and for resident or patient education. It has also found its way to the operation theatre where it is used to fabricate customized surgical tools or patient-specific implants. Several authors have highlighted significant benefits when 3D printing is used for specific indications in spine surgery. Novel applications of this technology in spine surgery have also been described and though still in a nascent stage, these are important for this technology to sustain itself in the future. However, major limitations have also come to light with this technology in use. This article seeks to review the current status and applications of 3D printing in spinal surgery and its major drawbacks while briefly describing the essentials of the technology. It is imperative that the modern spine surgeon knows about this important innovation and when and how it can be applied to improve surgical outcomes.

Applications of Three-Dimensional Printing in Surgery

Three-dimensional (3D) printing is a rapidly advancing technology in the field of surgery. This article reviews its contemporary applications in 3 aspects of surgery, namely, surgical planning, implants and prostheses, and education and training. Three-dimensional printing technology can contribute to surgical planning by depicting precise personalized anatomy and thus a potential improvement in surgical outcome. For implants and prosthesis, the technology might overcome the limitations of conventional methods such as visual discrepancy from the recipient's body and unmatching anatomy. In addition, 3D printing technology could be integrated into medical school curriculum, supplementing the conventional cadaver-based education and training in anatomy and surgery. Future potential applications of 3D printing in surgery, mainly in the areas of skin, nerve, and vascular graft preparation as well as ear reconstruction, are also discussed. Numerous trials and studies are still ongoing. However, scientists and clinicians are still encountering some limitations of the technology including high cost, long processing time, unsatisfactory mechanical properties, and suboptimal accuracy. These limitations might potentially hamper the applications of this technology in daily clinical practice.

Advantages and disadvantages of 3-dimensional printing in surgery: A systematic review

BACKGROUND

Three-dimensional (3D) printing is becoming increasingly important in medicine and especially in surgery. The aim of the present work was to identify the advantages and disadvantages of 3D printing applied in surgery.

METHODS

We conducted a systematic review of articles on 3D printing applications in surgery published between 2005 and 2015 and identified using a PubMed and EMBASE search. Studies dealing with bioprinting, dentistry, and limb prosthesis or those not conducted in a hospital setting were excluded.

RESULTS

A total of 158 studies met the inclusion criteria. Three-dimensional printing was used to produce anatomic models (n = 113, 71.5%), surgical guides and templates (n = 40, 25.3%), implants (n = 15, 9.5%) and molds (n = 10, 6.3%), and primarily in maxillofacial (n = 79, 50.0%) and orthopedic (n = 39, 24.7%) operations. The main advantages reported were the possibilities for preoperative planning (n = 77, 48.7%), the accuracy of the process used (n = 53, 33.5%), and the time saved in the operating room (n = 52, 32.9%); 34 studies (21.5%) stressed that the accuracy was not satisfactory. The time needed to prepare the object (n = 31, 19.6%) and the additional costs (n = 30, 19.0%) were also seen as important limitations for routine use of 3D printing.

CONCLUSION

The additional cost and the time needed to produce devices by current 3D technology still limit its widespread use in hospitals. The development of guidelines to improve the reporting of experience with 3D printing in surgery is highly desirable.

Haptics-assisted Virtual Planning of Bone, Soft Tissue, and Vessels in Fibula Osteocutaneous Free Flaps

Supplemental Digital Content is available in the text.

Virtual surgery planning has proven useful for reconstructing head and neck defects by fibula osteocutaneous free flaps (FOFF). Benefits include improved healing, function, and aesthetics, as well as cost savings. But available virtual surgery planning systems incorporating fibula in craniomaxillofacial reconstruction simulate only bone reconstruction without considering vessels and soft tissue.

Rapid prototyping-assisted maxillofacial reconstruction

Rapid prototyping (RP) technologies have found many uses in dentistry, and especially oral and maxillofacial surgery, due to its ability to promote product development while at the same time reducing cost and depositing a part of any degree of complexity theoretically. This paper provides an overview of RP technologies for maxillofacial reconstruction covering both fundamentals and applications of the technologies. Key fundamentals of RP technologies involving the history, characteristics, and principles are reviewed. A number of RP applications to the main fields of oral and maxillofacial surgery, including restoration of maxillofacial deformities and defects, reduction of functional bone tissues, correction of dento-maxillofacial deformities, and fabrication of maxillofacial prostheses, are discussed. The most remarkable challenges for development of RP-assisted maxillofacial surgery and promising solutions are also elaborated.

Computer-aided trauma simulation system with haptic feedback is easy and fast for oral-maxillofacial surgeons to learn and use

PURPOSE

Computer-assisted surgical (CAS) planning tools have become widely available in craniomaxillofacial surgery, but are time consuming and often require professional technical assistance to simulate a case. An initial oral and maxillofacial (OM) surgical user experience was evaluated with a newly developed CAS system featuring a bimanual sense of touch (haptic).

MATERIALS AND METHODS

Three volunteer OM surgeons received a 5-minute verbal introduction to the use of a newly developed haptic-enabled planning system. The surgeons were instructed to simulate mandibular fracture reductions of 3 clinical cases, within a 15-minute time limit and without a time limit, and complete a questionnaire to assess their subjective experience with the system. Standard landmarks and linear and angular measurements between the simulated results and the actual surgical outcome were compared.

RESULTS

After the 5-minute instruction, all 3 surgeons were able to use the system independently. The analysis of standardized anatomic measurements showed that the simulation results within a 15-minute time limit were not significantly different from those without a time limit. Mean differences between measurements of surgical and simulated fracture reductions were within current resolution limitations in collision detection, segmentation of computed tomographic scans, and haptic devices. All 3 surgeons reported that the system was easy to learn and use and that they would be comfortable integrating it into their daily clinical practice for trauma cases.

CONCLUSION

A CAS system with a haptic interface that capitalizes on touch and force feedback experience similar to operative procedures is fast and easy for OM surgeons to learn and use.

Frame-based cranial reconstruction

The authors report on the first experiences with the prototype of a surgical tool for cranial remodeling. The device enables the surgeon to transfer statistical information, represented in a model, into the disfigured bone. The model is derived from a currently evolving databank of normal head shapes. Ultimately, the databank will provide a set of standard models covering the statistical range of normal head shapes, thus providing the required template for any standard remodeling procedure as well as customized models for intended overcorrection. To date, this technique has been used in the surgical treatment of 14 infants (age range 6-12 months) with craniosynostosis. In all 14 cases, the designated esthetic result, embodied by the selected model, has been achieved, without morbidity or mortality. Frame-based reconstruction provides the required tools to precisely realize the surgical reproduction of the model shape. It enables the establishment of a self-referring system, feeding back postoperative growth patterns, recorded by 3D follow-up, into the model design.

Augmented reality patient-specific reconstruction plate design for pelvic and acetabular fracture surgery

PURPOSE

The objective of this work is to develop a preoperative reconstruction plate design system for unilateral pelvic and acetabular fracture reduction and internal fixation surgery, using computer graphics and augmented reality (AR) techniques, in order to respect the patient-specific morphology and to reduce surgical invasiveness, as well as to simplify the surgical procedure.

MATERIALS AND METHODS

Our AR-aided implant design and contouring system is composed of two subsystems: a semi-automatic 3D virtual fracture reduction system to establish the patient-specific anatomical model and a preoperative templating system to create the virtual and real surgical implants. Preoperative 3D CT data are taken as input. The virtual fracture reduction system exploits the symmetric nature of the skeletal system to build a "repaired" pelvis model, on which reconstruction plates are planned interactively. A lightweight AR environment is set up to allow surgeons to match the actual implants to the digital ones intuitively. The effectiveness of this system is qualitatively demonstrated with 6 clinical cases. Its reliability was assessed based on the inter-observer reproducibility of the resulting virtual implants.

RESULTS

The implants designed with the proposed system were successfully applied to all cases through minimally invasive surgeries. After the treatments, no further complications were reported. The inter-observer variability of the virtual implant geometry is 0.63 mm on average with a standard deviation of 0.49 mm. The time required for implant creation with our system is 10 min on average.

CONCLUSION

It is feasible to apply the proposed AR-aided design system for noninvasive implant contouring for unilateral fracture reduction and internal fixation surgery. It also enables a patient-specific surgical planning procedure with potentially improved efficiency.

Generation of normative pediatric skull models for use in cranial vault remodeling procedures

PURPOSE

While the goal of craniofacial reconstruction surgery is to restore the cranial head shape as much towards normal as possible, for the individual patient, there is, in fact, no normal three-dimensional (3D) model to act as a guide. In this project, we generated a library of normative pediatric skulls from which a guiding template could be fabricated for a more standardized, objective and precise correction of craniosynostosis.

METHODS

Computed tomography data from 103 normal subjects aged 8-12 months were compiled and a 3D computational model of the skull was generated for each subject. The models were mathematically registered to a baseline model for each month of age within this range and then averaged, resulting in a single 3D point cloud. An external cranial surface was subsequently passed through the point cloud and its shape and size customized to fit the head circumference of individual patients.

RESULTS

The resultant fabricated skull models provide a novel and applicable tool for a detailed, quantitative comparison between the normative and patient skulls for preoperative planning and practice for a variety of craniofacial procedures including vault remodeling. Additionally, it was possible to extract the suprafrontal orbit anatomy from the normative model and fabricate a bandeau template to guide intraoperative reshaping.

CONCLUSIONS

Normative head shapes for pediatric patients have wide application for craniofacial surgery including planning, practice, standarized operative repair, and standardized measurement and reporting of outcomes.

Creating a virtual surgical atlas of craniofacial procedures: Part I. Three-dimensional digital models of craniofacial deformities

BACKGROUND

Three-dimensional digital animation can enable surgeons to create anatomically accurate, virtual models of normal and pathologic human anatomy. From these models, surgical procedures can be digitally performed, recorded, and distributed as a teaching tool or as a virtual surgical atlas. The idea of a virtual surgical atlas has recently become a part of contemporary surgical teaching. In the field of craniofacial surgery, no such educational tool exists. Presented is the first part of the creation of a virtual atlas of craniofacial surgical procedures: the three-dimensional digital modeling of pathologic deformities commonly treated by craniofacial surgeons.

METHODS

Three-dimensional craniofacial models were constructed using Maya 8.5. A skeletally "normal" craniofacial skeleton was first produced from a preexisting digital skull using Bolton tracings as a reference. The remaining soft-tissue elements were then added to create an anatomically complete three-dimensional face. The "normal" model was then deformed in Maya to produce specific craniofacial deformities using computed tomographic scans, cephalograms, and photographs as a reference. One of the craniofacial deformity models was created directly from computed tomographic data.

RESULTS

One model of the normal face and eight pathologic models of craniofacial deformities were created: microgenia, micrognathia, prognathia, temporomandibular joint ankylosis, maxillary hypoplasia, Crouzon syndrome with and without the need for cranial vault expansion, and bicoronal craniosynostosis.

CONCLUSIONS

For the first time, anatomically accurate three-dimensional digital models of craniofacial deformities have been created. The models are the first step in the creation of a virtual surgical atlas of craniofacial procedures.

Rapid prototyping in craniofacial surgery: using a positioning guide after zygomatic osteotomy - A case report

INTRODUCTION

The management of post-traumatic deformity in the midface region poses challenges for the maxillofacial surgeon. Ensuring symmetry after zygomatic osteotomy can be difficult and precise positioning of the osteotomised bony fragments requires careful treatment planning. It may be necessary to use a coronal flap to allow the surgeon to compare the contralateral zygomatic bone to allow symmetrical reduction. The authors present a new technique for the positioning of osteotomised zygomatic bones using a combination of computer assisted surgical simulation and rapid prototyping.

METHOD

A patient presented to our unit with a post-traumatic zygomatic deformity. Using surgical simulation software the displaced zygomatic bone was osteotomised and placed in the idéal position on a three-dimensional computed tomography scan (3D CT). The position was determined by reference to the contralateral zygoma. In addition the repositioning of the soft tissues was simulated. A surgical guide which allowed intraoperative positioning of the osteotomised zygoma was manufactured by a rapid prototyping process. Use of the guide allowed a minimally invasive approach to the affected zygoma. The post-operative results were compared to the predicted outcome.

RESULTS

The post-operative appearance was satisfactory and corresponded well with the predicted result. There was a significant reduction in operative time compared to the previous management of similar cases.