Combined application of virtual surgery and 3D printing technology in postoperative reconstruction of head and neck cancers
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The complex anatomy of the head and neck creates a formidable challenge for surgical reconstruction. However, good functional reconstruction plays a vital role in the quality of life of patients undergoing head and neck surgery. Precision medical treatment in the field of head and neck surgery can greatly improve the prognosis of patients with head and neck tumors. In order to achieve better shape and function, a variety of modern techniques have been introduced to improve the restoration and reconstruction of head and neck surgical defects. Digital surgical technology has great potential applications in the clinical treatment of head and neck cancer because of its advantages of personalization and accuracy.
Our department has identified the value of modern digital surgical techniques in the field of head and neck surgery and has explored its utility, including CAD/CAM technology and VR technology. We have achieved good results in the reconstruction of head and neck surgical resection defects.
In this article, we share five typical cases from the department of head and neck surgery where the reconstruction was performed with the assistance of digital surgical technology.
KeywordsHead and neck cancer Reconstruction Digital surgery Virtual reality 3 dimensional printing Computer aided design Computer aided manufacturing
Computer aided design
Computer aided manufacturing
The anatomy of head and neck is exceptionally complex. Numerous key organs, known vessels and named nerves converge here, leading to differences in tumors types and growth patterns. Only a complete resection of the tumor can improve survival, quality of life, and create conditions for safe adjuvant treatment. Patients often need to undergo radical resection for aggressive malignant tumors to ensure sufficient resection margins. Lack of effective reconstruction techniques in the distant past left doctors and patients with poor results and significant impacts on quality of life. With the development of microsurgical techniques, free tissue transfer reconstruction is now standard of care. In order to achieve complete resection and efficient and effective functional reconstruction, it is particularly important to develop a reasonable preoperative surgical plan and execute that plan in the operating room.
At present, conventional imaging techniques such as ultrasound, CT and MRI can reflect the relationship between the tumor and adjacent important tissues. When the soft tissue or osseous structure of the head and neck needs to be reconstructed after cancer extirpation, two-dimensional imaging can limit a comprehensive assessment and analysis of the disease. This makes preoperative planning difficult as it can be difficult to appreciate the surgical defect in three dimensions.
With the development of digital technology the possibility of better preoperative three dimensional planning became a reality. Virtual surgery (virtual reality and augmented reality), CAD, CAM (3D printing), RP, 3D navigation and robotics have been rapidly applied and combined to be used in a personalized approach making precision medicine possible in head and neck surgery. Among these, CAD, CAM and VR technology are the most commonly used [1, 2].
CAD technology uses CT or MRI imaging data to analyze 3D defects of anticipated extirpative surgery. This makes consideration of using RP by 3D printer to better model the resulting defect. This has led to a more personalized approach taking into consideration each individual patients unique requirements.
Characteristics of five patients in this study
ERM + CT
RR + RT
ERPL +FND + FF
ERPL +RND + FF + AF
SM + FF
Main Digital Technology
CAD, CAM, VR, RP
3D, CAD, CAM, RP
Motion of upper limb
Post-operatively the reconstruction did well. The patient was followed up with good facial morphology and postoperative CT imaging showed good contour of the fibula. The fixation position of titanium plate screws were accurate (Fig. 4l), and the occlusion was normal (Fig. 4m).
We used CAD/CAM technology to develop a surgical treatment plan. Based on the tumor size and areas of invasive disease, segmental mandibulectomy was simulated. We modeled the simulated cut with the iliac bone in the defect area in the width, thickness, and angle. The place for osteotomy of the iliac bone was determined, and the virtual reconstruction was performed. A three dimensional solid model, osteotomy template of the lesion, and the iliac bone were developed through a 3D printer. Pre-bent titanium plates were prepared by the reconstructive model of rapid prototyping.
Following the simulated surgery, the left mandibular segmental resection with free iliac myocutaneous flap reconstruction with titanium plate fixation were performed under the general anesthesia. (Fig. 5b, c). Prefabricated titanium plates were used to fix the iliac bone to the mandibular resection defect (Fig. 5d). The defect in the oral cavity was repaired with the muscle flap. During the follow-up, the second stage of dental implants were placed 1.5 years after the first stage of operation (Fig. 5e). Currently the patient had a nice facial appearance with an excellent occlusion, and a functional oral cavity (Fig. 5f).
Discussion and conclusions
With the rapid development of medical imaging digitalization, computer assisted surgical simulation based on the 3D reconstruction have developed rapidly. 3D reconstruction of complex head and neck cancers can elucidate important information such as tumor location, scope of invasion, blood supply, and also provide the potential for preoperative simulation for complex defect repair. In the past, “three dimensional” imaging still depended on a “one-dimensional” modalities. The advent of high-precision 3D printers and VR technologies have significantly changed the potential of virtual visualization. After a simple post-processing and format conversion, the reconstructed image can directly produce a vivid and precise physical model.
In the early 1990s, scholars began to apply CAD and 3D printing techniques to the diagnosis and treatment of complex head and neck and maxillofacial diseases. These two techniques improved diagnostic accuracy by 29.60%, procedural precision by 36.23%, and shortened operative time by 17.63% . In the twenty-first century, CAD and 3D printing techniques have been widely used for reconstruction of complex defects in head and neck surgery [4, 5]. These techniques provide an accurate preoperative simulation and intraoperative surgical ablative plan. Additionally, enhanced imaging provides a reference for the length and shape of fixed titanium plates and screw positions for osseous reconstruction. In recent years, some scholars have pioneered the comprehensive application of CAD combined with 3D printing technology to guide free vascularized fibula free flap reconstruction of maxillary defects [6, 7]. Some scholars have also taken the lead in introducing VR technology in the development of operative planning and pre-operative simulation .
Although CAD/CAM and VR technology has a wide range of potential applications in ablative surgical planning and complex reconstruction of head and neck cancer, it is still in the exploratory stage. In China, the above technologies are available in many units or companies with required hardware and software. Our department has accumulated some experience in this field. We concede that the application of these technologies increases the cost of treatment and extended surgeon time in preparation. We believe, however, that the cost and time can be reduced in a center that has the expertise and can use the technology in batches. At present, the annual application of these digital technologies in our center is about 30–50 cases per year. According to our application experience, preoperative preparation time needs about 2–4 days, and we feel it is an acceptable delay for both the patient and the surgeon. In recent years, some studies have suggested that use of digital technology does not significantly increase the cost of treatment, and has obvious benefits for multi-segment osteotomy cases . We have identified several advantages using this technology: 1) the surgical margin of the tumor can be determined according to the invasion of solid tumor and the anatomical characteristics of the patient maximizing preservation of maxillofacial bone tissue with oncological possibility; 2) the personalized 3D-printed bone model and osteotomy plates are convenient for surgeons to visualize tumors preoperatively to confirm the location and extent of the tumor, location, and length, as well as the angle of the osteotomies, which can improve three-dimensional repeatability ; 3) in the case of severe osseous deformity caused by tumor invasion, the data from the contralateral normal mandible can be collected and inverted by mirror image technology. After setting up the mirror model, the titanium plate is pre-bent with preset plate and screw positioning for the best fixation. During the operation, to maximize oral cavity function and cosmetic results, a plastic drill guide can be used as a template for harvesting an exact fibula construct with precise osteotomies for detailed reconstruction . CAD/CAM group has advantages in function and aesthetic achievement ; 4) these 3D-models can be used preoperatively for modeling titanium mesh to repair large mandibular defects, or even to directly manufacture personalized titanium mandibular prostheses for immediate reconstruction .; and 5) patient-specific models can improve doctor-patient communication. These modes are convenient for patients to understand the details of the operation, predict the cosmetic effects of surgery, and understand the possible risks during perioperative planning, and may help improve patient compliance.
Our department has made full use of the various applications of CAD/CAM techniques to assist in the reconstruction of the segmental defect of the mandible and maxilla (for example case 4). A complete set of digital techniques was used to simulate the operation to determine the scope of the procedure and to design the shape of the osseous graft. We used virtual practice to predict the possible difficulties in the operation and fine tune the surgical plan (Fig. 4b, c). We strive to determine the best surgical procedure and optimize cosmetic and oncologic outcomes with enhanced surgeon-patient communication prior to the operation. Personalized modeling of the bone, the planned ablative defect and the reconstruction with titanium plate (Fig. 4d-g) makes surgical planning more accurate with less guess work during the operation. It also reduces operative time and postoperative complications. Additionally, it optimizes postoperative reconstruction cosmetics by contouring the titanium plate and positioning screws in best fixed position by digital technology (Fig. 4i, k, m).
After success with multiple applications of CAD/CAM technology in the reconstruction of head and neck defects, our department is expanding applications of VR technology to visually explore human anatomy. Previous studies have shown that VR technology is not only a good way of simulating surgery for surgeons , but also enables surgeons to better understand the relationship between surgical approaches and adjacent structures to improve surgeon proficiency and reduce unanticipated complications during surgery [14, 15].
In our experience, when compared with previous methods of two-dimensional preoperative assessment, surgeries using VR technology require more complex and time-intensive preoperative assessment. However, we feel there are more advantages to this approach for the reconstruction of complex head and neck defects. VR technology can provide morphological and functional information by simultaneously combining the advantages of CT in bone invasion with MRI in soft tissue involvement by tumor . By building a virtual stereoscopic medical image, a realistic 720 degree 3D image model provides the surgeon with the most complete preoperative assessment. The headgear and data gloves can be used to adjust the size and direction of the field of vision for an immersive operative experience. When a surgeon performed the simulated operation, multiple assistants can interact by wearing a device that allows the entire medical team to become familiar with the patient’s condition and improve operative coordination. Patients can participate in the surgical process, experience the simulation, understand the disease, and optimize patient-physician communication. Moreover, the use of VR technology does not require material input or capital investment.
In unique cases, such as the carotid body tumor above, when both imaging and virtual images suggest that the tumor is closely linked to the blood vessels, VR technology can allow the physician visualize the intraluminal dimension. Based on a CT or MRI angiogram the involvement of the vessel can be anticipated (Fig. 2d, e). This is particularly useful in cases of post-radiation imaging when tissues are significantly fibrotic and exposing vascular anatomy can be challenging. Preoperative knowledge of vascular invasion can help surgeons anticipate possible need for increased operative time or vascular surgeon consultation.
To improve oral cavity function digital surgery can more precisely anticipate the resection with wide surgical margins and customize fibular free flap reconstruction in oral cavity tumors with mandibular invasion.
We conclude that computer-assisted surgery for personalized reconstruction of complex defects of the head and neck has role in clarifying tumor anatomy relationships, reconstructing complex osseous and soft tissue defects and defining vascular lesions such as aneurysms and vascular tumors. This information leads to precise surgical treatment of head and neck cancer patients. However, its application in head and neck surgery is still limited. More systematic clinical results are needed to confirm the overall and reliable clinical value. Nonetheless, we believe that using computer-aided digital surgical technology to evaluate, simulate, formulate, and implement operative plans is an important trend in the future of head and neck surgery.
The author thanks the Academy of Life Sciences of University of Electronic Science and Technology for its technical support in the diagnosis and treatment of related cases.
CL, RS, WT, ALD, and YS were mainly involved in the patient treatment/surgery and data Collection and follow up, as well as writing of the manuscript. YC, WW, and GL critically revised the manuscript and provided critical input. All authors read and approved the final manuscript.
Ethics approval and consent to participate
The need for ethic approval was approved by the institutional review board of Sichuan Cancer Hospital & Institute, Sichuan Cancer Center. Written informed consent was obtained from the patient to report and publish individual patient data.
Consent for publication
Written informed consent was obtained from all patients to report and publish all patients’ clinical data including images that may be identifiable. A copy of the written consent is available for review by the editor of this journal.
The authors declare that they have no competing interests.
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