Computer-aided Surgical Simulation Research Articles

A Modified Method of Proximal Segment Alignment After Sagittal Split Ramus Osteotomy for Patients With Mandibular Asymmetry

The purpose of this study was to evaluate a modified method of aligning the proximal segment after bilateral sagittal split ramus osteotomy (BSSO) in the treatment of patients with facial asymmetry. Eleven patients with mandibular excess and facial asymmetries were enrolled in this prospective study. The surgery was planned according to a computer-aided surgical simulation protocol. In addition, the proximal segment on the hypoplastic side was intentionally flared out after the distal segment was rotationally set back. If the gap between the proximal and distal segments was too wide, then bone grafts were used. The surgery was completed according to the computerized plan. The proximal segment on the hypoplastic side was fixed with bicortical lag screws, and the proximal segment on the hyperplastic side was fixed with a 4-hole titanium miniplate. Postoperative evaluation was performed 6months after surgery. Statistical analyses were performed. All surgeries were completed uneventfully. Of the 11 patients, 4 also underwent genioplasty and 3 underwent bone grafting to fill in the gap and smooth the anterior step. The physicians and patients were satisfied with the surgical outcomes. Only 1 patient underwent a secondary revision using an onlay hydroxyapatite implant. Results of statistical analyses showed that the computerized surgical plan could be accurately transferred to the patients at the time of surgery and the surgical outcomes achieved with this modified method were better than with the routine method of aligning the proximal and distal segments in maximal contact. The present modified method of aligning the proximal segment for BSSO can effectively correct mandibular asymmetry and obviate a secondary revision surgery.

Virtual surgical planning in orthognathic surgery.

Computer-aided surgical simulation has greatly enhanced the efficiency and accuracy of orthognathic surgery for correction of dentofacial deformities. Virtual surgical planning (VSP) improves the efficiency of the presurgical work-up and provides an opportunity to illustrate the multidimensional correction at the dental and skeletal level. VSP provides preoperative insight into the surgical intervention and the fabrication of cutting jigs/guides and templates can help decrease intraoperative surgical inaccuracies. VSP is rapidly becoming the standard of care for surgical treatment planning of dentofacial deformities.

Mesh optimization of vessel surface model for computer-aided simulation of percutaneous coronary intervention.

Percutaneous coronary intervention is the gold standard to coronary diseases in the past decades due to much less trauma and quick recovery. However, due to the traits of minimal invasiveness, clinicians have to defeat the difficulties in eye-hand coordination during the procedure, which also makes it a non-trivial task in the catheterization lab. The computer-aided surgical simulation is designed to provide a reliable tool for the early stage of the training of the procedure. In this simulation system, the surface model of the vessels contribute the major part in the virtual anatomic environment. On the other hand, heavy interactions between the virtual surgical tools and the model surface occur during the training. In order to achieve acceptable performances, the patient-specific vessel surface model needs further process to adapt to this situation. We proposed in this paper an approach to optimize the meshes that consist the surface model with its application in consideration. The connectivity of the surface model is firstly checked. Next a smooth processing is applied without modifying the geometry of the largest-connected surface. Then the quantities of the polygons consisting the model surface are eliminated both dramatically and appropriately. The resultant surface model is applied in the validation test interacting with the virtual guidewire.

Does computer-aided surgical simulation improve efficiency in bimaxillary orthognathic surgery?

The purpose of this study was to compare the efficiency of bimaxillary orthognathic surgery using computer-aided surgical simulation (CASS), with cases planned using traditional methods. Total doctor time was used to measure efficiency. While costs vary widely in different localities and in different health schemes, time is a valuable and limited resource everywhere. For this reason, total doctor time is a more useful measure of efficiency than is cost. Even though we use CASS primarily for planning more complex cases at the present time, this study showed an average saving of 60min for each case. In the context of a department that performs 200 bimaxillary cases each year, this would represent a saving of 25 days of doctor time, if applied to every case. It is concluded that CASS offers great potential for improving efficiency when used in the planning of bimaxillary orthognathic surgery. It saves significant doctor time that can be applied to additional surgical work.

Prosthodontic and Surgical Management of a Completely Edentulous Patient with a Severe Class III Skeletal Maxillomandibular Relationship: A Clinical Report

This article describes a multidisciplinary approach combining surgical and prosthodontic treatment of a completely edentulous patient who presented with a severe skeletal class III relationship and was diagnosed as American College of Prosthodontists Prosthodontic Diagnostic Index (ACP PDI) class IV. The use of a complete denture serving as diagnostic tool, surgical guide, and definitive restoration is presented. Computer-aided surgical simulation was used to achieve an accurate diagnostic and surgical plan. Maxillary Lefort class I and mandibular sagittal split osteotomy surgical treatment was performed to correct arch discrepancy. The surgical procedure demonstrated a clinically acceptable maxillomandibular relationship and stability. The patient was satisfied with the esthetics and demonstrated improved oral function following prosthesis insertion.

Accuracy of a Computer-Aided Surgical Simulation Protocol for Orthognathic Surgery: A Prospective Multicenter Study

The purpose of this prospective multicenter study was to assess the accuracy of a computer-aided surgical simulation (CASS) protocol for orthognathic surgery. The accuracy of the CASS protocol was assessed by comparing planned outcomes with postoperative outcomes of 65 consecutive patients enrolled from 3 centers. Computer-generated surgical splints were used for all patients. For the genioplasty, 1 center used computer-generated chin templates to reposition the chin segment only for patients with asymmetry. Standard intraoperative measurements were used without the chin templates for the remaining patients. The primary outcome measurements were the linear and angular differences for the maxilla, mandible, and chin when the planned and postoperative models were registered at the cranium. The secondary outcome measurements were the maxillary dental midline difference between the planned and postoperative positions and the linear and angular differences of the chin segment between the groups with and without the use of the template. The latter were measured when the planned and postoperative models were registered at the mandibular body. Statistical analyses were performed, and the accuracy was reported using root mean square deviation (RMSD) and the Bland-Altman method for assessing measurement agreement. In the primary outcome measurements, there was no statistically significant difference among the 3 centers for the maxilla and mandible. The largest RMSDs were 1.0 mm and 1.5° for the maxilla and 1.1 mm and 1.8° for the mandible. For the chin, there was a statistically significant difference between the groups with and without the use of the chin template. The chin template group showed excellent accuracy, with the largest positional RMSD of 1.0 mm and the largest orientation RMSD of 2.2°. However, larger variances were observed in the group not using the chin template. This was significant in the anteroposterior and superoinferior directions and the in pitch and yaw orientations. In the secondary outcome measurements, the RMSD of the maxillary dental midline positions was 0.9 mm. When registered at the body of the mandible, the linear and angular differences of the chin segment between the groups with and without the use of the chin template were consistent with the results found in the primary outcome measurements. Using this computer-aided surgical simulation protocol, the computerized plan can be transferred accurately and consistently to the patient to position the maxilla and mandible at the time of surgery. The computer-generated chin template provides greater accuracy in repositioning the chin segment than the intraoperative measurements.

New Methods to Evaluate Craniofacial Deformity and to Plan Surgical Correction

The success of cranio-maxillofacial (CMF) surgery depends not only on surgical techniques, but also upon an accurate surgical plan. Unfortunately, traditional planning methods are often inadequate for planning complex cranio-maxillofacial deformities. To this end, we developed 3D computer-aided surgical simulation (CASS) technique. Using our CASS method, we are able to treat patients with significant asymmetries in a single operation which in the past was usually completed in two stages. The purpose of this article is to introduce our CASS method in evaluating craniofacial deformities and planning surgical correction. In addition, we discuss the problems associated with the traditional surgical planning methods. Finally, we discuss the strength and pitfalls of using three-dimensional measurements to evaluate craniofacial deformity.

Outcome study of computer-aided surgical simulation in the treatment of patients with craniomaxillofacial deformities.

The purpose of this study was to determine whether the surgical outcomes achieved with computer-aided surgical simulation (CASS) are better than those achieved with traditional methods. Twelve consecutive patients with craniomaxillofacial (CMF) deformities were enrolled. According to the CASS clinical protocol, a 3-dimensional computer composite skull model for each patient was generated and reoriented to the neutral head posture. These models underwent 2 virtual surgeries: 1 was based on CASS (experimental group) and the other was based on traditional methods 1 year later (control group). Once the 2 virtual surgeries were completed, 2 experienced oral and maxillofacial surgeons at 2 different settings evaluated the 2 surgical outcomes. They were blinded to the planning method used on the virtual models and each other's evaluation results. The primary outcome was overall CMF skeletal harmony. The secondary outcomes were individual maxillary, mandibular, and chin harmonies. Statistical analyses were performed. Overall CMF skeletal harmony achieved with CASS was statistically significantly better than that achieved with traditional methods. In addition, the maxillary and mandibular surgical outcomes achieved with CASS were significantly better. Furthermore, although not included in the statistical model, the chin symmetry achieved by CASS tended to be better. A regression model was established between mandibular symmetry and overall CMF skeletal harmony. The surgical outcomes achieved with CASS are significantly better than those achieved with traditional planning methods. In addition, CASS enables the surgeon to better correct maxillary yaw deformity, better place proximal/distal segments, and better restore mandibular symmetry. The critical step in achieving better overall CMF skeletal harmony is to restore mandibular symmetry.

Construction of computer-aided simulation system for carpal anatomy

Objective To design and construct a 3-dimensional carpal anatomy computer-aided simulation system (3DCACAS) which can realize three-dimensional segmentation and anatomical dissection of the carpal, diagnose and analysis, surgical design, outcome evaluation and 3D measurement. Methods The software ran on Windows XP operating system, was developed with Microsoft Visual C + + platform and was in virtue of OpenGL. In the system, optimized Marching Cube(MC)was used in 3D reconstruction. 3D display and control was designed by OpenGL. 3D arbitrary region segmentation was realized by spatial segmentation and pixels superimposition was used in 3D measurement. Results A computer-aided surgical simulation system for carpal anatomy was developed. Its functions included 3D reality display of images, 3D segmentation, 3D measurement and computer-aided surgical design of internal fixation of the carpus. Conclusion The construction of 3DCACAS provides a reference for studying carpal kinematics, diagnosing pathological changes of carpal ailment and planning surgeries around the carpus. Key words: Carpal bones; Imaging,three-dimensional; Kinematics

Computer-Aided Surgical Simulation and Navigation in Reconstruction of Old Complicated Cranio-maxillofacial Fractures

Reconstruction of the old complicated craniomaxillofacial (CMF) fractures requires a precise and safe therapy to improve the functional and aesthetic outcome. In this paper, an image-guided simulation and navigation system was developed (Navi-CMFS)to improve the accuracy and reliability of the reconstruction surgery of the old complicated CMF fractures. Pre-operative planning and simulation based on 3-dimension (3D) model can provide enough 3D information of the patient. Intra-operative navigation can widen the surgeons’ vision field and locate the continually updated position of the instruments and the patient, to avoid injury to the important tissue. Clinical studies were conducted on 6 patients with complicated CMF fractures. Firstly, a virtual 3D skull model was reconstructed from pre-surgical image dataset information. In this virtual 3D model, surgeon moved or rotated the fractured bone and relocated it in a desired site according to the mirrored part from the unaffected side. After patient-to-image registration, the surgical instrument and patient were tracked in real-time by the optical tracking system during operation. In this way the old complicated CMF fractures were relocated satisfactorily guided by the virtual image. The results show that this system is proved to be essential helpful in reconstruction of the old complicated CMF fractures.

Computer-Aided Surgical Simulation in Mandibular Reconstruction: Maximizing Outcomes in Single-Stage Fibula Free Flap Reconstruction with Immediate Dental Implants

Plastic and Reconstructive Surgery: October 2010 - Volume 126 - Issue - p 88-89 doi: 10.1097/01.prs.0000388811.12683.1f

Three-dimensional surgical simulation

In this article, we discuss the development of methods for computer-aided jaw surgery, which allows us to incorporate the high level of precision necessary for transferring virtual plans into the operating room. We also present a complete computer-aided surgery system developed in close collaboration with surgeons. Surgery planning and simulation include construction of 3-dimensional surface models from cone-beam computed tomography, dynamic cephalometry, semiautomatic mirroring, interactive cutting of bone, and bony segment repositioning. A virtual setup can be used to manufacture positioning splints for intraoperative guidance. The system provides further intraoperative assistance with a computer display showing jaw positions and 3-dimensional positioning guides updated in real time during the surgical procedure. The computer-aided surgery system aids in dealing with complex cases with benefits for the patient, with surgical practice, and for orthodontic finishing. Advanced software tools for diagnosis and treatment planning allow preparation of detailed operative plans, osteotomy repositioning, bone reconstructions, surgical resident training, and assessing the difficulties of the surgical procedures before the surgery. Computer-aided surgery can make the elaboration of the surgical plan a more flexible process, increase the level of detail and accuracy of the plan, yield higher operative precision and control, and enhance documentation of cases.

Poster Board Number: 77: Computer Aided Surgical Simulation (CASS) Following High Velocity, Multisegmental Panfacial Trauma: A Novel Technique in Facial Reconstruction

Statement of the Problem: Complex injuries as a result of trauma offer a challenge for the reconstructive surgeon. High velocity trauma causes tissue loss, displacement of facial bones/malocclusions, and ultimately a loss of 3 dimensional projection. Historically, treatment objectives were achieved using 2 dimensional radiographs and dental models, as well as eyeballing of misaligned segments. The consequence of this inaccurate planning often produced suboptimal results requiring revision surgeries.

New Clinical Protocol to Evaluate Craniomaxillofacial Deformity and Plan Surgical Correction

Cranio-Maxillofacial Surgery (CMF) involves the correction of congenital and acquired conditions of the head and face. In the United States, a significant number of patients require surgery for these types of conditions. They include patients with of congenital and developmental deformities of the CMF region (17 million) 1-7, defects after tumor ablation (28,000 new patients per year)8, post-traumatic defects (200,000 per year)9, 10 and deformities of the temporomandibular joint (6000 patients per year require prosthetic and autogenous TMJ reconstruction)11, 12. The latest figures indicate that 33,000 US servicemen and women have been wounded in action in both Operation Iraqi Freedom and Operation Enduring Freedom.13 It is estimated the one fourth to one third of them suffered head and neck injuries.14 The surgical correction of CMF deformities is among the most challenging. The success of these surgeries depends not only on the technical aspects of the operation, but also, to a larger extent, on the formulation of a precise surgical plan.15-24 Over the last 50 years, there have been significant improvements in the technical aspects of surgery, i.e. rigid fixation, resorbable materials, distraction osteogenesis, minimally invasive approaches, etc. However, the planning methods have mostly remained unchanged.17, 18, 20, 24 It is clear that many of the unwanted surgical outcomes are the result of deficient planning. The need to improve the traditional surgical planning methods has led our group to develop a 3D computer-aided surgical simulation (CASS) system to plan CMF surgery. We have utilized this system in maxillofacial surgery23, 25-27, craniofacial surgery28, trauma, distraction osteogenesis28-30 and TMJ reconstruction31. Using this system, a doctor can perform “virtual surgery” and create a 3D prediction of the patient's surgical outcomes, as if they are performing surgery in the operating room. We have documented the clinical feasibility18, 24, the accuracy32 and cost-effectiveness33 of this system. Our CASS system incorporates 3 distinctive features and innovations: 1) multiple imaging modalities are used to create an accurate model of the craniofacial skeleton; 2) special techniques are employed to orient the computerized bone model in the natural head position (NHP); and 3) Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) techniques are used to fabricate accurate surgical splints and templates to transfer the surgical plan to the operating room. The purpose of this article is to present our CASS planning protocol.

Simulation of surgical glenoid resurfacing using three-dimensional computed tomography of the arthritic glenohumeral joint: The amount of glenoid retroversion that can be corrected

The magnitude of glenoid retroversion that can be surgically corrected in total shoulder arthroplasty and still enable implantation of a glenoid component has not been established. We hypothesized that increased retroversion will require smaller glenoid components for successful implantation when the glenoid is surgically corrected and that correction beyond 20 degrees of retroversion is not feasible without peg penetration. Using 3-dimensional models created from computed tomography of 19 patients with advanced shoulder osteoarthritis, we simulated glenoid resurfacing on varying degrees of retroverted, osteoarthritic glenoids using an in-line 3-peg glenoid component and asymmetric reaming to correct version. Glenoids with preoperative retroversion of less than 12 degrees could always be implanted with 46-mm and 52-mm glenoid components at neutral version without vault violation. Conversely, glenoids with greater than 18 degrees of preoperative retroversion could not be implanted at neutral version due to vault violation from the pegs. The average preoperative glenoid retroversion of patients in which a 46-mm glenoid was implanted at neutral version was 8.9 degrees +/- 6.4 degrees compared with 19.0 degrees +/- 7.1 degrees for those that could not be implanted at neutral (P = .005). Computer-aided surgical simulation shows that glenoid retroversion is a critical factor in determining successful glenoid implantation. Smaller sized glenoid components allow for greater version correction and less residual postsimulation retroversion when an in-line pegged component is used.

Computer-aided surgical simulation for orthognathic surgery

Computer-aided surgical simulation for orthognathic surgery

Computer-aided surgical simulation for complex craniomaxillofacial surgery

Computer-aided surgical simulation for complex craniomaxillofacial surgery

The role of computer‐aided 3D surgery and stereolithographic modelling for vector orientation in premaxillary and trans‐sinusoidal maxillary distraction osteogenesis

Maxillary distraction osteogenesis is a challenging procedure when it is performed with internal submerged distractors due to obligation of setting accurate distraction vectors. Five patients with severe maxillary retrognathy were planned with Mimics 10.01 CMF and Simplant 10.01 software. Distraction vectors and rods of distractors were arranged in 3D environment and on STL models. All patients were operated under general anaesthesia and complete Le Fort I downfracture was performed. All distractions were performed according to orientated vectors. All patients achieved stable occlusion and satisfactory aesthetic outcome at the end of the treatment period. Preoperative bending of internal maxillary distractors prevents significant loss of operation time. 3D computer-aided surgical simulation and model surgery provide accurate orientation of distraction vectors for premaxillary and internal trans-sinusoidal maxillary distraction. Combination of virtual surgical simulation and stereolithographic models surgery can be validated as an effective method of preoperative planning for complicated maxillofacial surgery cases.

Real-time haptic incision simulation using FEM-based discontinuous free-form deformation

Computer-aided surgical simulation is a topic of increasingly extensive research. Computer graphics, geometrical modelling and finite-element analysis all play major roles in these simulations. Furthermore, real-time response, interactivity and accuracy are crucial components in any such simulation system. A major effort has been invested in recent years to find ways to improve the performance, accuracy and realism of existing systems. In this paper, we extend the work of [Sela G, Schein S, Elber G. Real-time incision simulation using discontinuous free form deformation. In: Cotin S, Metaxas DN, editors. Medical simulation: International symposium, 2004. Lecture notes in computer science, vol. 3078. Springer; 2004. p. 114–123], in which we used discontinuous free-form deformations (DFFD) to artificially simulate real-time surgical operations. The presented scheme now uses accurate data from a finite-element model (FEM), which simulates the motion response of the tissue around the scalpel, during incision. The data are then encoded once into the DFFD, representing the simulation over time. In real-time, The DFFD is applied to the vertices of the surface mesh at the actual incision location and time. The presented scheme encapsulates and takes advantage of both the speed of the DFFD application, and the accuracy of a FEM. In addition, the presented system uses a haptic force feedback device in order to improve realism and ease of use.

Clinical Feasibility of Computer-Aided Surgical Simulation (CASS) in the Treatment of Complex Cranio-Maxillofacial Deformities

The purpose of this study was to establish clinical feasibility of our 3-dimensional computer-aided surgical simulation (CASS) for complex craniomaxillofacial surgery. Five consecutive patients with complex craniomaxillofacial deformities, including hemifacial microsomia, defects after tumor ablation, and deformity after TMJ reconstruction, were used. The patients' surgical interventions were planned by using the authors' CASS planning method. Computed tomography (CT) was initially obtained. The first step of the planning process was to create a composite skull model, which reproduces both the bony structures and the dentition with a high degree of accuracy. The second step was to quantify the deformity. The third step was to simulate the entire surgery in the computer. The maxillary osteotomy was usually completed first, followed by mandibular and chin surgeries. The shape and size of the bone graft, if needed, was also simulated. If the simulated outcomes were not satisfactory, the surgical plan could be modified and simulation could be started over. The final step was to create surgical splints. Using the authors' computer-aided designing/manufacturing techniques, the surgical splints and templates were designed in the computer and fabricated by a stereolithographic apparatus. To minimize the potential risks to the patients, the surgeries were also planned following the current planning methods, and acrylic surgical splints were created as a backup plan. All 5 patients were successfully planned using our CASS planning method. The computer-generated surgical splints were successfully used on all patients at the time of the surgery. The backup acrylic surgical splints and plans were never used. Six-week postoperative CT scans showed the surgical plans were precisely reproduced in the operating room and the deformities were corrected as planned. The results of this study have shown the clinical feasibility of our CASS planning method. Using our CASS method, we were able to treat patients with significant asymmetries in a single operation that in the past was usually completed in 2 stages. We were also able to simulate different surgical procedures to create the appropriate plan. The computerized surgical plan was then transferred to the patient in the operating room using computer-generated surgical splints.