Computer-aided Surgical Planning Research Articles

A Symmetry-Based Superposition Method for Planning and Surgical Outcome Assessment

Computer-aided surgical planning has been widely used to increase the safety and predictability of surgery. The validation of the target of surgical planning to surgical outcomes on a patient-specific model is an important issue. The aim of this research was to develop a robust superposition method to assess the deviation of planning and outcome by using the symmetrical characteristic of the affected target. The optimal symmetry plane (OSP) of an object is usually used to evaluate the degree of symmetry of an object. We proposed a refined OSP-based contouring method to transfer a complex three-dimensional superposition operation into two dimensions. We compared the typical iterative closest point (ICP) algorithm with the refined OSP-based contouring method and examined the differences between them. The results using the OSP-based method were much better than the traditional method. As for processing time, the OSP-based contouring method was 11 times faster than the ICP method overall. The proposed method was not affected by the metallic artifacts from medical imaging or geometric changes due to surgical intervention. This technique can be applied for post-operative assessment, such as quantifying the differences between surgical targets and outcomes as well as performing long-term medical follow-up.

Overcoming Delayed Diagnosis of Chronic Invasive Fungal Sinusitis in the Immunocompetent Patient: A Case Report

Study Design Case report. Objective To highlight the diagnostic and treatment dilemma associated with chronic invasive fungal sinusitis (CIFS) in the immunocompetent individual. Methods The patient was initially treated for chronic bacterial sinusitis with antibiotic therapy and multiple surgical debridement with no evidence of fungal organisms. Following the completion of the left partial maxillectomy, mucormycosis was finally identified on histopathology, and the appropriate antimicrobial therapy was initiated. During this time, the patient received an interim maxillary obturator for speech and oral function. Following the resolution of CIFS, a computed tomography (CT) of the face was obtained for computer-aided surgical planning for a vascularized fibula flap reconstruction with endosseous dental implants using patient-specific surgical cutting guides and a reconstruction plate. Results Optimal esthetic and functional outcomes were achieved following the placement of the definitive dental prosthesis. The patient remained free of disease and without pain 2 years postoperatively. Conclusions Chronic invasive fungal sinusitis in the immunocompetent patient remains rare; however, delayed diagnosis can lead to inadequate treatment and extensive soft and hard tissue necrosis. Obtaining sufficient tissue sampling is essential for a definitive diagnosis of CIFS. This report demonstrates the challenge in diagnosing CIFS and the importance of the multidisciplinary approach to treat CIFS associated with extensive involvement of the maxilla.

Computer-aided Surgical Planning and Osteosynthesis Plates for Bimaxillary Orthognathic Surgery: A Study of 14 Consecutive Patients.

All patients who underwent bimaxillary OS in 2017-2018 with preoperative computed tomography (CT) scan, postoperative day 1 CT scan, and at least 6 months follow-up were included in the study. Group 1 utilized maxillary preprinted plates (maxilla only). Group 2 utilized bimaxillary preprinted plates (maxillomandibular). Eight cephalometric landmarks to evaluate the movements were chosen. The ranges of the angle between the sella/nasion plane and the nasion/A plane (SNA), the angle between the sella/nasion plane and the nasion/B plane (SNB), and the angle created by the A point' nasion' and B point' which measures the relative position of maxilla to mandible, were analyzed to assess the angular change. Mean-squared displacement and the SD of the distances were used to assess movement in space. Twenty-three patients (nine in group 1 and 14 in group 2) met the inclusion criteria. Results showed interarch relationships using custom plates for both jaws with ANB 0.4 compared to ANB 1.4 for maxillary custom plates only. Mandibular landmarks showed greater variation, and the t test study revealed the right mandibular first molar landmark showing the greatest variation (P = 0.03). Custom osteosynthesis plates for OS show good accuracy for the maxilla and higher variation in the mandible. Further studies will determine the margin of error that cannot be corrected with postoperative orthodontics.

Reproducibility of a three-dimensional skeletal-based craniofacial orientation method for virtual surgical planning

Inadequate craniofacial orientation of computed tomography (CT) scans can have significant implications in all three planes of space. The purpose of this study was to present the reproducibility of a 3-dimensional skeletal-based method of craniofacial orientation for virtual surgical planning. The protocol was defined by landmarks commonly used for cephalometry, and required identification of basion, nasion, right porion, and right orbitale, and navigation in all CT views (coronal, sagittal, and axial) for correction of yaw, roll, and pitch. Reproducibility of the method was assessed using eight CT scans that were randomly selected and anonymised. The observer group consisted of six oral and maxillofacial surgeons with varying levels of experience (resident or faculty) who performed craniofacial orientation according to the proposed method. Results were expected to be below 2° of variation, when overall accuracy as well as the influence of the academic level of the observers and symmetry of the evaluated anatomy, were considered as independent variables. Overall accuracy for all cases and for yaw, roll, and pitch were always below 2° of variation, without influence of level of experience and symmetry. Interobserver assessment was categorised as excellent in all instances, and intraobserver evaluation demonstrated consistency in the orientation of all axes. The proposed craniofacial orientation protocol presented in this study is easy to learn, applicable to computer-aided surgical planning, and can be performed by the non-technical clinician, resulting in excellent reproducibility and consistency.

SkullEngine: A Multi-Stage CNN Framework for Collaborative CBCT Image Segmentation and Landmark Detection.

Accurate bone segmentation and landmark detection are two essential preparation tasks in computer-aided surgical planning for patients with craniomaxillofacial (CMF) deformities. Surgeons typically have to complete the two tasks manually, spending ~12 hours for each set of CBCT or ~5 hours for CT. To tackle these problems, we propose a multi-stage coarse-to-fine CNN-based framework, called SkullEngine, for high-resolution segmentation and large-scale landmark detection through a collaborative, integrated, and scalable JSD model and three segmentation and landmark detection refinement models. We evaluated our framework on a clinical dataset consisting of 170 CBCT/CT images for the task of segmenting 2 bones (midface and mandible) and detecting 175 clinically common landmarks on bones, teeth, and soft tissues. Experimental results show that SkullEngine significantly improves segmentation quality, especially in regions where the bone is thin. In addition, SkullEngine also efficiently and accurately detect all of the 175 landmarks. Both tasks were completed simultaneously within 3 minutes regardless of CBCT or CT with high segmentation quality. Currently, SkullEngine has been integrated into a clinical workflow to further evaluate its clinical efficiency.

Bone Tunnel Placement Determination Method for 3D Images and Its Evaluation for Anterior Cruciate Ligament Reconstruction.

Anterior cruciate ligament (ACL) injury causes knee instability which affects sports activity involving cutting and twisting motions. The ACL reconstruction surgery replaces the damaged ACL with artificial one which is fixed to the bone tunnels opened by the surgeon. The outcome of the ACL reconstruction is strongly related to the placement of the bone tunnels, therefore, the optimization of tunnel drilling technique is an important factor to obtain satisfactory surgical results. The quadrant method is used for the post-operative evaluation of the ACL reconstruction surgery, which evaluates the bone tunnel opening sites on the lateral 2D X-ray radiograph. For the purpose of applying the quadrant method to the pre-operative knee MRI, we have synthesized the pseudo lateral 2D X-ray radiograph from the patients' knee MRI. This paper proposes a computer-aided surgical planning system for the ACL reconstruction. The proposed system estimates appropriate bone tunnel opening sites on the pseudo lateral 2D X-ray radiograph synthesized from the pre-operative knee MRI. In the experiment, the proposed method was applied to 98 subjects including subjects with osteoarthritis. The experimental results showed that the proposed method can estimate the bone tunnel opening sites accurately. The other experiment using 36 healthy patients showed that the proposed method is robust to the knee shape deformation caused by disease. It is verified that the proposed method can be applied to subjects with osteoarthritis.

Introduction of an algorithm for planning of autologous fibular transfer in mandibular reconstruction based on individual bone curvatures.

Reconstruction of the mandible with autologous transplants is a challenging task and current computer-aided surgical planning remains cumbersome. Thus, the aim of the present study was to create an automated computational approach for this procedure. The developed algorithm is based on curves following characteristic anatomical features. Geometrical data from a physiological mandible and a fibula were used to generate six different defects, and geometrical accordance was investigated to demonstrate the applicability of the method with different reconstruction parameters (n = 309). The method proved to be applicable, it recognized given clinical constraints and the values of accordance could be used to quantify the success of reconstructions. With the present approach, the complex three-dimensional task of mandibular reconstruction was simplified, and thus it allows implementation in clinical routine. The computational planning that is proposed may be used to design cutting guides or as geometrical input data for real-time navigated surgery.

Mandibular Reconstruction Using ProPlan CMF: A Review

ProPlan CMF (Depuy Synthes, Solothurn, Switzerland, and Materialise, Leuven, Belgium) is a computer-aided surgical virtual planning service using an online meeting with professional medical engineers and transfers patient-specific surgical guide to the virtual plan. Moreover, prebent reconstruction plates or patient-specific computer-aided manufacturing-fabricated reconstruction can also be used. This service started in 2011. Currently, it is widely used in Europe. Current status of mandibular reconstruction with ProPlan CMF vertical planning service with the surgical guide was reviewed. The accuracy was excellent in terms of contact of the osteotomized parts and the contact to the remaining skeleton. The authors found that currently, a small number of reports regarding the mandibular reconstruction with virtual planning service and surgical guides are available. These reports also have a small number of cases and short-term follow-up results. In this situation, this review revealed that (1) mainly the resection guides, cutting guides, and patient-specific mandible reconstruction plates were adequately well fitted to the surgical site intraoperatively, (2) the ischemic time might be more reduced than that of the conventional surgery (3) the accuracy of computer-assisted surgery in the mandibular reconstruction was clinically acceptable, and (4) condyle positions after the computer-assisted surgery was mainly normal. The higher additional cost than that of the conventional technique is presently an issue. Large-scale clinical studies and long-term follow-up studies are demanded.

Computer-aided Surgical Planning of Anterior Cruciate Ligament Reconstruction in MR Images

Anterior cruciate ligament (ACL) injury causes knee joint instability, and effects on sports performance. Therefore, ACL reconstruction is essential to keep their high performance. It is well known that the outcome of ACL reconstruction is strongly related to the placement and orientation of the bone tunnel. Therefore, optimization of tunnel drilling technique is an important factor to obtain satisfactory surgical results. Current procedure relies on arthroscopic evaluation and there is a risk of damaging arteries and ligaments during surgery. The damages may reduce the accuracy and reproducibility of ACL reconstruction. As a postoperative evaluation method, a quadrant method has been used to evaluate the placement and orientation of the bone tunnel in X-ray radiography. This study proposes a computer-aided surgical planning system for evaluating ACL insertion site and orientation using magnetic resonance (MR) images. We first introduce MR image based the quadrant method to determine the ACL insertion site for preoperative patients. It also evaluates the 3-D spatial relationship between the planning femoral drilling hole and arteries around the femoral condyle. This system has been applied to ACL injured patients, it may increase the accuracy and reproducibility of ACL bone tunnel, and it can evaluate a risk of damaging the surrounding arteries and ligaments.

The role of automatic computer-aided surgical trajectory planning in improving the expected safety of stereotactic neurosurgery.

Minimal invasion computer-assisted neurosurgical procedures with various tool insertions into the brain may carry hemorrhagic risks and neurological deficits. The goal of this study is to investigate the role of computer-based surgical trajectory planning tools in improving the potential safety of image-based stereotactic neurosurgery. Multi-sequence MRI studies of eight patients who underwent image-guided neurosurgery were retrospectively processed to extract anatomical structures-head surface, ventricles, blood vessels, white matter fibers tractography, and fMRI data of motor, sensory, speech, and visual areas. An experienced neurosurgeon selected one target for each patient. Five neurosurgeons planned a surgical trajectory for each patient using three planning methods: (1) conventional; (2) visualization, in which scans are augmented with overlays of anatomical structures and functional areas; and (3) automatic, in which three surgical trajectories with the lowest expected risk score are automatically computed. For each surgeon, target, and method, we recorded the entry point and its surgical trajectory and computed its expected risk score and its minimum distance from the key structures. A total of 120 surgical trajectories were collected (5 surgeons, 8 targets, 3 methods). The surgical trajectories expected risk scores improved by 76% ([Formula: see text], two-sample student's t test); the average distance of a trajectory from nearby blood vessels increased by 1.6 mm ([Formula: see text]) from 0.6 to 2.2 mm (243%). The initial surgical trajectories were changed in 85% of the cases based on the expected risk score and the trajectory distance from blood vessels. Computer-based patient-specific preoperative planning of surgical trajectories that minimize the expected risk of vascular and neurological damage due to incorrect tool placement is a promising technique that yields consistent improvements.

Interactive design of dental implant placements through CAD-CAM technologies: from 3D imaging to additive manufacturing

In the field of oral rehabilitation, the combined use of 3D imaging technologies and computer-guided approaches allows the development of reliable tools to be used in preoperative assessment of implant placement. In particular, the accurate transfer of the virtual planning into the operative field through surgical guides represents the main challenge of modern dental implantology. Guided implant positioning allows surgical and prosthetic approaches with minimal trauma by reducing treatment time and decreasing patient’s discomfort. This paper aims at defining a CAD/CAM framework for the accurate planning of flapless dental implant surgery. The system embraces three major applications: (1) freeform modelling, including 3D tissue reconstruction and 2D/3D anatomy visualization, (2) computer-aided surgical planning and customised template modelling, (3) additive manufacturing of guided surgery template. The tissue modelling approach is based on the integration of two maxillofacial imaging techniques: tomographic scanning and surface optical scanning. A 3D virtual maxillofacial model is created by matching radiographic data, captured by a CBCT scanner, and surface anatomical data, acquired by a structured light scanner. The pre-surgical planning process is carried out and controlled within the CAD application by referring to the integrated anatomical model. A surgical guide is then created by solid modelling and manufactured by additive techniques. Two different clinical cases have been approached by inserting 11 different implants. CAD-based planned fixture placements have been transferred into the clinical field by customised surgical guides, made of a biocompatible resin and equipped with drilling sleeves.

Tele-Robotic Assisted Dental Implant Surgery with Virtual Force Feedback

The dental implant surgical applications full of risk because of the complex anatomical architecture of craio-maxillofacial area. Therefore, the surgeons move towards computer-aided planning for surgeries and then implementation using robotic assisted tele-operated techniques. This study divided into four main parts. The first part is developed by computer-aided surgical planning by image modalities .The second part is based on Virtual Surgical Environment through virtual force feedback haptic device. The third part is implemented the experimental surgery by integrating the prototype surgical manipulator with the haptic device poses using inverse kinematics method. The fourth part based on monitoring the robotic manipulator pose by using image guided navigation system to calculate the position error of the surgical manipulator. Thus, this tele-robotic system is able to comprehend the sense of complete practice, improve skills and gain experience of the surgeon during the surgery. Finally, the experimental outcomes show in satisfactory boundaries. DOI : http://dx.doi.org/10.11591/telkomnika.v12i1.3124

Reliability of computer designed surgical guides in six implant rehabilitations with two years follow-up

ObjectiveTo evaluate the reliability and accuracy of computer-designed surgical guides in osseointegrated oral implant rehabilitation. Materials and methodsSix implant rehabilitations, with a total of 17 implants, were completed with computer-designed surgical guides, performed with the master model developed by muco-compressive and muco-static impressions. In the first case, the surgical guide had exclusively mucosal support, in the second case exclusively dental support. For all six cases computer-aided surgical planning was performed by virtual analyses with 3D models obtained by dental scan DICOM data.The accuracy and stability of implant osseointegration over two years post surgery was then evaluated with clinical and radiographic examinations. Radiographic examination, performed with digital acquisitions (RVG – Radio Video graph) and parallel techniques, allowed two-dimensional feedback with a margin of linear error of 10%. ResultsImplant osseointegration was recorded for all the examined rehabilitations. During the clinical and radiographic post-surgical assessments, over the following two years, the peri-implant bone level was found to be stable and without appearance of any complications. The margin of error recorded between pre-operative positions assigned by virtual analysis and the post-surgical digital radiographic observations was as low as 0.2mm. SignificanceComputer-guided implant surgery can be very effective in oral rehabilitations, providing an opportunity for the surgeon: (a) to avoid the necessity of muco-periosteal detachments and then (b) to perform minimally invasive interventions, whenever appropriate, with a flapless approach.

Computer-aided surgical planning in the treatment of soft-tissue sarcoma

Soft-tissue sarcoma resections are often highly complex procedures that demand meticulous pre-operative planning in order to maximise the potential for complete excision with clear margins, while preserving vital neurovascular structures and muscle groups. We present a computer-aided model for surgical planning using Microsoft Powerpoint as a tool for cross referencing magnetic resonance images and normal anatomical diagrams. Using this system the operator follows a sequence of pre-planned steps, minimising intra-operative decision making and unexpected adverse events. Four case studies are discussed. The visual plan optimises the potential to meet surgical and oncological goals, and serves as an excellent adjunct to the operation note for documentation of the procedure.

Using two palpable measurements improves the subject-specific femoral modeling

Subject-specific musculoskeletal models are essential to biomedical research and clinical applications, such as customized joint replacement, computer-aided surgical planning, gait analysis and automated segmentation. Generating these models from CT or magnetic resonance imaging (MRI) is time and resource intensive, requiring special skills. Therefore, in many studies individual bone models are approximated by scaling a generic template. Thus, the primary goal of this study was to determine a set of clinically available parameters (palpable measures and demographic data) that could improve the prediction of femoral dimensions, as compared to predicting these variables using uniform scaling based on palpable length. Similar to previous non-homogenous anthropometric scaling methods, the non-homogenous scaling method proposed in this study improved the prediction over uniform scaling of five key femoral measures. Homogenous scaling forces all dimensions of an object to be scaled equally, whereas non-homogenous scaling allows the dimensions to be scaled independently. The largest improvement was in femoral depth, where the coefficient of determination ( r 2) improved from 0.22 (homogenous) to 0.60 (non-homogeneous). In general, the major advantage of this non-homogenous scaling method is its ability to support the accurate and rapid generation of subject-specific femoral models since all parameters can be collected clinically, without imaging or invasive methods.

Perspective: The Ethics and Economics of Heroic Surgery

A brief report in the 10 August 2000 issue of the New England Journal of Medicine described a case of conjoined twins and their separation at Childrens Hospital in Boston, Massachusetts. That report described the extraordinary surgery; immediately after birth, made possible by the use of computer-aided presurgical planning.[1] The media picked up the story, and a first page article appeared in The New York Times on the same day.[2] Two days earlier, on 8 August, conjoined twins were born in Malta in a case that stirred even media attention. Eventually they underwent surgical separation in the United Kingdom against the parents' wishes.[3] Reflecting on the case presented in the New England Journal of Medicine has led one of the coauthors of that report to enlist a bioethicist to help consider its ethical aspects. This essay is the outcome of that joint endeavor. The two cases are similar in important ways. Although the U.K. twins were conjoined at their pelves while the Massachussetts twins were conjoined at their chests and abdomens, in both cases, one of the twins was perfused with blood pumped by her twin sister's heart. This phenomenon is known as twin reversed arterial perfusion, and had not previously been reported in the medical literature in conjunction with conjoined twinning. Also, in both cases, both twins would ultimately have died had they not been separated. Finally, the expected outcome of both cases was comparable and is so far confirmed by the facts: one twin was sacrificed in the surgery, and the surviving twin will have a relatively normal development and lead a healthy life, although she may not be entirely free from complications. Both surgeries are without question remarkable accomplishments, and the use of computer-aided surgical planning in the Massachusetts case was a great technical advance. Yet while the individual cases seem to have turned out successfully from a medical perspective, they also have troubling social implications. want other parents with this problem to try to save their kids, said the father of the twins described in the New England Journal of Medicine.[2] He will probably have his wish. In the Massachusetts case, the parents accepted the need to bring about the death of one twin in order to save the other. We agree that, if the choice is between saving one twin or allowing both of them to die, it is, other things being equal, better to save one. But it is never the case that everything else is equal. Other factors are always involved. Perhaps most importantly, there are always other cases--other patients, other children, other social needs. What is striking about these cases are their implications for the allocation of scarce public health care resources. The New York Times reported that the treatment of the Massachusetts case cost more than $500,000, partly paid by the Medicaid programs in Massachussetts and New Jersey, and the rest absorbed by the hospitals. We believe that the cost may actually have been much more, given that it involved three surgical procedures and six months of hospital care, most of it in the intensive care unit. Assume, nonetheless, that the cost of the procedure was approximately $500,000. Much has been written both about escalating health care costs and the need for their containment, and about the questionable practices that health maintenance organizations and third party payers employ to limit costs. Yet there is now a widespread consensus that something must be done to limit health care costs. In a recent U.S. Supreme Court case involving a suit by a patient who was denied necessary tests, Justice David H. Souter bluntly declared that rationing health care was a legitimate public goal.[5] The case of the Massachusetts twins illustrates the difficulties that stand in the way of solving this problem, given how health care decisions are currently made. It is not difficult to estimate the significance of $500,000 for health care. …

Computer-aided surgical planning for implantation of hearing aids based on CT data in a VR environment.

A study was undertaken to assess the feasibility of a preoperative fitting test for an implantable hearing aid in a virtual reality (VR) environment. High-resolution spiral computed tomography (CT) of the mastoid bone was performed, and the results of a mastoidectomy were simulated with manual segmentation on a standard medical workstation. CT was also performed on a temporal bone specimen obtained at real mastoidectomy, and the bone margins were segmented automatically with threshold-based techniques. A triangulated surface representation of the bone structures including the mastoid cavity was generated. These data as well as the computer-aided design (CAD) files of the medical devices were transferred into a VR environment. The CAD components of the hearing aid were manipulated to simulate the surgical implantation procedure. Merging CAD data of an implantable hearing aid with CT data of the temporal bone in a VR environment was shown to be a feasible method of providing three-dimensional information for the presurgical determination of fit and mountability. Advances in hardware and software are expected to improve the usability of this method. Although clinical studies are needed, these results may serve as an impetus for exploring the use of low-cost, widely available VR computer equipment in a potentially broad field of clinical applications.

A Mathematical Formulation for 3D Quasi-Static Multibody Models of Diarthrodial Joints

This study describes a genera] set of equations for quasi-static analysis of three-dimensional multibody systems, with a particular emphasis on modeling of diarthrodial joints. The model includes articular contact, muscle forces, tendons and tendon pulleys, ligaments, and the wrapping of soft tissue structures around bone and cartilage surfaces. The general set of equations governing this problem are derived using a consistent notation for all types of links, which can be converted conveniently into efficient computer codes. The computational efficiency of the model is enhanced by the use of analytical Jacobians, particularly in the analysis of articular surface contact and wrapping of soft tissue structures around bone and cartilage surfaces. The usefulness of the multibody model is demonstrated by modeling the patellofemoral joint of six cadaver knees, using cadaver-specific data for the articular surface and bone geometries, as well as tendon and ligament insertions and muscle lines of actions. Good accuracy was observed when comparing the model patellar kinematic predictions to experimental data (mean ± stand, dev. error in translation: 0.63 ± 1.19 mm, 0.10 ± 0.71 mm, -0.29 ± 0.84 mm along medial, proximal, and anterior directions, respectively; in rotation: -1.41 ± 1.71°, 0.27 ±2.38°, -1.13 ± 1.83° in flexion, tilt and rotation, respectively). The accuracy which can be achieved with this type of model, and the computational efficiency of the algorithm employed in this study may serve in many applications such as computer-aided surgical planning, and real-time computer-assisted surgery in the operating room.