Computer-assisted Orthopaedic Surgery Research Articles

A hand-eye calibration method for augmented reality applied to computer-assisted orthopedic surgery

Purpose Recent technology advances in Augmented Reality (AR) is creating an opportunity for a paradigm shift in the field of Computer Assisted Surgery (CAS). Despite having the potential of being a promising technology in clinical applications, its accuracy, robustness, and performances under specific environmental conditions have not been fully investigated and evaluated. In an attempt to address the limitations and uncertainties that arise from using computer vision, we propose a Hand-Eye (HE) based approach to determine an invariant mapping between the HoloLens headset (i.e., rigid body defined by a unique set of passive markers) and the OHMDs virtual camera. Methods In order to achieve the required precision for using the Microsoft HoloLens in a surgical application, an invariant mapping was estimated. First, a set of non-collinear retroreflective markers were rigidly attached to the Microsoft HoloLens headset. Consequently, the OHMDs's intrinsic parameters, as well as their radial and tangential lenses distortion coefficients, were determined by solving simultaneously a set of homogeneous system of equations by using nonlinear optimization techniques. The accuracy of the proposed HE based method has been evaluated by using a retro-projection error estimation method. Results Initially, a surgical frame has been anchored to the organ of interest. After loading the patient-specific dataset, a hologram of the organ of interest appears in front of the user's initial position. Correspondences between the hologram and the fiducial markers can then be established by using the tracked surgical pointer and then be mapped with respect to the surgical frame. After finishing this process, an orthonormal basis is created in the physical space, which has its counterpart in the image space and, therefore, a transformation can be determined to map the hologram with respect to the surgical frame. Conclusions OHMDs may be able to create an opportunity for a paradigm shift in the field of CAS, since all this detailed information could easily be displayed on virtual and interactive screens in operating rooms on the same time and in real time. A very important aspect of using such OHMDs is that it can be very intuitive, especially among inexperienced surgeon, since surgical instruments and maneuvers motions are represented with respect to the surgeon's visual system and, therefore, attention disruptions are more likely to be reduced in terms of the surgeon's gaze, considering that the surgeon would not need to be searching for a conventional display located at static location in the operating room.

Software Framework for the Creation and Application of Personalized Bone and Plate Implant Geometrical Models.

Computer-Assisted Orthopaedic Surgery (CAOS) defines a set of techniques that use computers and other devices for planning, guiding, and performing surgical interventions. The important components of CAOS are accurate geometrical models of human bones and plate implants, which can be used in preoperational planning or for surgical guiding during an intervention. Software framework which is introduced in this study is based on the Model-View-Controller (MVC) architectural pattern, and it uses 3D models of bones and plate implants developed by the application of the Method of Anatomical Features (MAF). The presented framework may be used for preoperative planning processes and for the production of personalized plate implants. The main idea of the research was to develop a novel integrated software framework which will provide improved personalized healthcare to the patient, and at the same time, provide the surgeon with more control over the patient's treatment and recovery.

Improved Surface-Based Registration of CT and Intraoperative 3D Ultrasound of Bones.

The intraoperative registration of preoperative CT volumes is a key process of most computer-assisted orthopedic surgery (CAOS) systems. In this work, is reported a new method for automatic registration of long bones, based on the segmentation of the bone cortical in intraoperative 3D ultrasound images. A bone classifier was developed based on features, obtained from the principal component analysis of the Hessian matrix, of every voxel in an intraoperative ultrasound volume. 3D freehand ultrasound was used for the acquisition of the intraoperative ultrasound volumes. Corresponding bone surface segmentations in ultrasound and preoperative CT imaging were used for the intraoperative registration. Validation on a phantom of the tibia produced encouraging results, with a maximum mean segmentation error of 0.34⁡mm (SD=0.26⁡mm) and a registration accuracy error of 0.64⁡mm (SD=0.49⁡mm).

Influence of the quality of intraoperative fluoroscopic images on the spatial positioning accuracy of a CAOS system.

Spatial positioning accuracy is a key issue in a computer-assisted orthopaedic surgery (CAOS) system. Since intraoperative fluoroscopic images are one of the most important input data to the CAOS system, the quality of these images should have a significant influence on the accuracy of the CAOS system. But the regularities and mechanism of the influence of the quality of intraoperative images on the accuracy of a CAOS system have yet to be studied. Two typical spatial positioning methods - a C-arm calibration-based method and a bi-planar positioning method - are used to study the influence of different image quality parameters, such as resolution, distortion, contrast and signal-to-noise ratio, on positioning accuracy. The error propagation rules of image error in different spatial positioning methods are analyzed by the Monte Carlo method. Correlation analysis showed that resolution and distortion had a significant influence on spatial positioning accuracy. In addition the C-arm calibration-based method was more sensitive to image distortion, while the bi-planar positioning method was more susceptible to image resolution. The image contrast and signal-to-noise ratio have no significant influence on the spatial positioning accuracy. The result of Monte Carlo analysis proved that generally the bi-planar positioning method was more sensitive to image quality than the C-arm calibration-based method. The quality of intraoperative fluoroscopic images is a key issue in the spatial positioning accuracy of a CAOS system. Although the 2 typical positioning methods have very similar mathematical principles, they showed different sensitivities to different image quality parameters. The result of this research may help to create a realistic standard for intraoperative fluoroscopic images for CAOS systems.

Total knee arthroplasties from the origin to navigation: history, rationale, indications.

Since the early 1970s, total knee arthroplasties have undergone many changes in both their design and their surgical instrumentation. It soon became apparent that to improve prosthesis durability, it was essential to have instruments which allowed them to be fitted reliably and consistently. Despite increasingly sophisticated surgical techniques, preoperative objectives were only met in 75% of cases, which led to the development, in the early 1990s, in Grenoble (France), of computer-assisted orthopaedic surgery for knee prosthesis implantation. In the early 2000s, many navigation systems emerged, some including pre-operative imagery ("CT-based"), others using intra-operative imagery ("fluoroscopy-based"), and yet others with no imagery at all ("imageless"), which soon became the navigation "gold standard". They use an optoelectronic tracker, markers which are fixed solidly to the bones and instruments, and a navigation workstation (computer), with a control system (e.g. pedal). Despite numerous studies demonstrating the benefit of computer navigation in meeting preoperative objectives, such systems have not yet achieved the success they warrant, for various reasons we will be covering in this article. If the latest navigation systems prove to be as effective as the older systems, they should give this type of technology a well-deserved boost.

A novel approach for intra-operative shape acquisition of the tibio-femoral joints using 3D laser scanning in computer assisted orthopaedic surgery.

Image registration (IR) is an important process of developing a spatial relationship between pre-operative data and the physical patient in the operation theatre. Current IR techniques for Computer Assisted Orthopaedic Surgery (CAOS) are time consuming and costly. There is a need to automate and accelerate this process. Bespoke quick, cost effective, contactless and automated 3D laser scanning techniques based on the DAVID Laserscanner method were designed. 10 cadaveric knee joints were intra-operatively laser scanned and were registered with the pre-operative MRI scans. The results are supported with a concurrent validity study. The average absolute errors between scan models were systematically less than 1 mm. Errors on femoral surfaces were higher than tibial surfaces (P<0.05). Additionally, scans acquired through the large exposure produced higher errors than the smaller exposure (P<0.05). This study has provided proof of concept for a novel automated shape acquisition and registration technique for CAOS.

Computer-assisted Orthopaedic Surgery.

Nowadays, operating rooms can be inefficient and overcrowded. Patient data and images are at times not well integrated and displayed in a timely fashion. This lack of coordination may cause further reductions in efficiency, jeopardize patient safety, and increase costs. Fortunately, technology has much to offer the surgical disciplines and the ongoing and recent operating room innovations have advanced preoperative planning and surgical procedures by providing visual, navigational, and mechanical computerized assistance. The field of computer-assisted surgery (CAS) broadly refers to surgical interface between surgeons and machines. It is also part of the ongoing initiatives to move away from invasive to less invasive or even noninvasive procedures. CAS can be applied preoperatively, intraoperatively, and/or postoperatively to improve the outcome of orthopaedic surgical procedures as it has the potential for greater precision, control, and flexibility in carrying out surgical tasks, and enables much better visualization of the operating field than conventional methods have afforded. CAS is an active research discipline, which brings together orthopaedic practitioners with traditional technical disciplines such as engineering, computer science, and robotics. However, to achieve the best outcomes, teamwork, open communication, and willingness to adapt and adopt new skills and processes are critical. Because of the relatively short time period over which CAS has developed, long-term follow-up studies have not yet been possible. Consequently, this review aims to outline current CAS applications, limitations, and promising future developments that will continue to impact the operating room (OR) environment and the OR in the future, particularly within orthopedic and spine surgery.

The Evolution of Computer-Assisted Total Hip Arthroplasty and Relevant Applications

In total hip arthroplasty (THA), the accurate positioning of implants is the key to achieve a good clinical outcome. Computer-assisted orthopaedic surgery (CAOS) has been developed for more accurate positioning of implants during the THA. There are passive, semi-active, and active systems in CAOS for THA. Navigation is a passive system that only provides information and guidance to the surgeon. There are 3 types of navigation: imageless navigation, computed tomography (CT)-based navigation, and fluoroscopy-based navigation. In imageless navigation system, a new method of registration without the need to register the anterior pelvic plane was introduced. CT-based navigation can be efficiently used for pelvic plane reference, the functional pelvic plane in supine which adjusts anterior pelvic plane sagittal tilt for targeting the cup orientation. Robot-assisted system can be either active or semi-active. The active robotic system performs the preparation for implant positioning as programmed preoperatively. It has been used for only femoral implant cavity preparation. Recently, program for cup positioning was additionally developed. Alternatively, for ease of surgeon acceptance, semi-active robot systems are developed. It was initially applied only for cup positioning. However, with the development of enhanced femoral workflows, this system can now be used to position both cup and stem. Though there have been substantial advancements in computer-assisted THA, its use can still be controversial at present due to the steep learning curve, intraoperative technical issues, high cost and etc. However, in the future, CAOS will certainly enable the surgeon to operate more accurately and lead to improved outcomes in THA as the technology continues to evolve rapidly.

Syndesmosis reduction by computer-assisted orthopaedic surgery with navigation: Feasibility and accuracy in a cadaveric study

IntroductionSyndesmotic disruption may be difficult to reduce and fix, and malreduction is associated with inferior outcomes. Intraoperative computed tomography (CT) can provide accurate assessment of syndesmotic reduction. We hypothesized that three-dimensional (3-D) computer-assisted orthopaedic surgery (CAOS) with navigation of syndesmotic reduction could avoid malreduction. Our goal was to assess feasibility and accuracy of such a technic in a cadaveric study. MethodEleven through-the-knee cadaveric specimens were used. Ankle CT as control was obtained prior to intervention. The syndesmosis was destabilized by sectioning the tibiofibular ligaments, producing a malreduction temporarily fixed with a Kirschner wire (K-wire). With reference base fixed to the tibia an acquisition scan was made. A K-wire was fixed to the fibula. The K-wire holding the syndesmosis malreduced was removed. The fibula was reduced within the syndesmosis under 3-D CAOS using a navigated K-wire. Once optimal position was obtained by referencing control images, the syndesmosis was fixed with a 3.5mm screw. A CT scan was performed to assess quality of reduction. ResultsPosition of the fibula in control and post-reduction CT scans showed a mean anterior-posterior displacement of 0.74 (±0.62)mm. The medial-lateral position measured a mean displacement of 0.68 (±0.76)mm. Rotation of the fibula revealed a mean difference of 0.99° (± 0.73). ConclusionIn this cadaveric study, CAOS with navigation allowed for very accurate syndesmosis reduction. This appears to be a promising technique to be confirmed by clinical study.

Intraoperative 3-Dimensional Computed Tomography and Navigation in Foot and Ankle Surgery.

Computer-assisted orthopedic surgery has developed dramatically during the past 2 decades. This article describes the use of intraoperative 3-dimensional computed tomography and navigation in foot and ankle surgery. Traditional imaging based on serial radiography or C-arm-based fluoroscopy does not provide simultaneous real-time 3-dimensional imaging, and thus leads to suboptimal visualization and guidance. Three-dimensional computed tomography allows for accurate intraoperative visualization of the position of bones and/or navigation implants. Such imaging and navigation helps to further reduce intraoperative complications, leads to improved surgical outcomes, and may become the gold standard in foot and ankle surgery. [Orthopedics.2016; 39(5):e1005-e1010.].

Physicians’ perspectives of adopting computer-assisted navigation in orthopedic surgery

ObjectivesUsing Computer-assisted orthopedic navigation surgery system (CAOS) has many advantages but is not mandatory to use during an orthopedic surgery. Therefore, opinions obtained from clinical orthopedists with this system are valuable. This paper integrates technology acceptance model and theory of planned behavior to examine the determinants of continued CAOS use to facilitate user management. MethodsOpinions from orthopedists who had used a CAOS for at least two years were collected through a cross-sectional survey to verify the research framework. Follow-up interviews with an expert panel based on their experiences of CAOS were conducted to reason the impacts of factors of the research framework. ResultsThe results show that factors of “perceived usefulness” and “facilitating condition” determine the intention to continue using CAOS, and “perceived usefulness” was driving by “complexity of task” and “social influence”. Additionally, support in practice from high-level managers had an influence on orthopedists’ satisfaction after using a CAOS. ConclusionsThe aging population is accompanied by the increasing requirements for medical care and medical care attendant expenses, especially in total knee replacement. More precision and improvements on survivorship of patients’ artificial joints are needed. This study facilitates suggestions in user management when encountering an obstacle in implementing a CAOS. Based on these findings, scientific and practical implications are then discussed.

Surgical navigation in paediatric orthopaedics.

Computer-assisted orthopaedic surgery was born in the 1990s. Nowadays, computer-assisted orthopaedic surgery is used for transpedicular screw fixation and for total knee arthroplasty.Patient-specific instrumentation is one type of computer-assisted surgery based on volumetric images, such as computed tomography or magnetic resonance imaging.In this article, possible applications of patient-specific instruments in paediatric orthopaedics are described. The use of patient-specific instrumentation for the correction of cubitus varus is given as an example with complex osteotomy. Another application for tarsal coalition resection is shown.A last example of using patient-specific instrumentation for both tumour resection and allograft reconstruction is illustrated.Patient-specific instruments based on computed tomography of the bone can increase peri-operative accuracy and decrease operative time. They are very helpful for the surgeon. Other applications are possible and will be probably developed in the future.Cite this article: Docquier PL, Paul L, TranDuy V. Surgical navigation in paediatric orthopaedics. EFORT Open Rev 2016;1:152-159. DOI: 10.1302/2058-5241.1.000009.

Computer-assisted orthopedic surgery

Computer-assisted surgery (CAS) has been used in orthopaedic surgery for over 20 years. Through real-time and quantitative feedback, it provides the surgeons the visibility of surgical anatomy, improves accuracy, reduces the outlier of the surgical results and maximizes the outcomes. CAS has been popularly applied in joint arthroplasty, bone osteotomy, implantation of screws in spine surgery, reconstruction of ligaments in sports medicine, open reduction and internal fixation of long-bone fracture and tumor surgery. The article is to overview the current CAS clinical application status and related outcomes. Whether the better postoperative images can translate into improved clinical functional outcomes deserves long term follow up.

Comment on "A Systematic Literature Review of Three Modalities in Technologically Assisted TKA".

We read with interest the recently published article in the journal discussing the systematic review of various new technologies for total knee arthroplasty. We have concerns about the published study [1] and would like to discuss it, along with our experience. The present systematic literature review is based on the articles and data collected from single indexing source, that is, PubMed (MEDLINE) index, and other well-known indices like EMBASE, SCOPUS, and so forth have not been searched for the similar keywords. The relevance of this systematic review would have improved by the inclusion of other data bases. The level of evidence of studies done for “kinetic sensor (KS)” is only either level III or level IV studies [2–5] which have been compared with level I or level II studies of the other two modalities, that is, Computer Assisted Orthopaedic Surgery (CAOS) and Patient Specific Instrumentation (PSI). Thus, this difference in the level of evidences of the studies between the two groups can lead to “selection bias” and hence the drawn inferences are not matchable and incorrect. The authors have shown that it contributes upwards of $1,000 per procedure in vendor charges to the hospital (for the cost of fabrication of cutting blocks) and up to $1,000 in additional charges for imaging. In our setup, the CT imaging costs only $100, and the cost of manufacturing of customized cutting blocks comes to less than $400 [6, 7]. We believe that, with increasing use of PSI, the vendors shall be able to provide the manufacturing of cutting blocks locally, and this will help in reducing the cost further. Although the authors have taken functional knee scores like KSS, WOMAC, and activity level scores for comparing the two modalities, any comparison of the postoperative mechanical axis was not included. Their conclusions have been drawn only from the postoperative functional knee scores like KSS, WOMAC, activity level scores, and so forth. It is well known that the primary objective of all these three technologically assisted TKA is to achieve a better and more accurate mechanical alignment postoperatively. Hence, not addressing this primary issue compromises the quality of this publication significantly. Based on the above reasoning, we suggest that more level I and II studies are required to prove the efficacy of the KS for its use in TKA.

Computer-Assisted Orthopedic Surgery: Current State and Future Perspective.

Introduced about two decades ago, computer-assisted orthopedic surgery (CAOS) has emerged as a new and independent area, due to the importance of treatment of musculoskeletal diseases in orthopedics and traumatology, increasing availability of different imaging modalities, and advances in analytics and navigation tools. The aim of this paper is to present the basic elements of CAOS devices and to review state-of-the-art examples of different imaging modalities used to create the virtual representations, of different position tracking devices for navigation systems, of different surgical robots, of different methods for registration and referencing, and of CAOS modules that have been realized for different surgical procedures. Future perspectives will also be outlined.

Can computer-assisted surgery help restore leg length and offset during THA? A continuous series of 321 cases

IntroductionTotal hip arthroplasty (THA) can bring about complications – particularly leg length differences – that are becoming increasingly litigious. Computer-assisted orthopedic surgery (CAOS) can help optimize the procedure, but its ability to effectively restore leg length is controversial. As a consequence, we carried out a study to determine: (1) its contribution to meeting leg length and offset objectives, (2) its reliability, by evaluating the correlation between radiological and navigation data, (3) its safety, by evaluating navigation-specific and non-specific complications. HypothesisCAOS will help to restore leg length within±5mm in more than 80% of cases. Material and methodsA series of 321 continuous cases of cementless THA implanted through the posterolateral approach using CAOS was analyzed retrospectively. With a minimum 1 year follow-up, we evaluated whether the leg length and offset goals were achieved, how well the navigation and radiology data were correlated and whether navigation-specific and non-specific complications occurred. Based on our hypothesis that 80% of patients would have less than 5mm leg length difference and the null hypothesis (PA=P0) with an alpha of 0.05, 200 observations were required to achieve a power of 90%. ResultsThe leg length and offset objectives were achieved in 83.3% and 88% of cases, respectively. Twenty-two patients required a heel wedge to compensate for leg length differences. The correlation between the radiology and surgical navigation data was satisfactory – the Pearson coefficient was 0.79 for length and 0.74 for offset. Intraoperative and postoperative complications or adverse events were found in 14.6% of cases; these were specific to CAOS in 12.1% of cases and non-specific in 2.5% of cases. ConclusionThis study shows the relevance of CAOS for achieving preoperative leg length objectives, with good correlation between navigation and radiology data, and without major complications. Level of evidenceIV – retrospective study.

Real-time assessment of bone structure positions via ultrasound imaging

Computer-assisted orthopedic surgery allows clinicians to have better results and decreases the number of early prosthetic replacements. Nevertheless, the patient follow-up from pre-operative diagnosis to post-operative control cannot be assessed in a constant referential. In this paper, a real-time algorithm that extracts bone edges from images and, then, derives bony landmarks from these edges is proposed. Indeed, we assess in real-time the bone structure positions via ultrasound imaging to create a useful referential for pre-operative, intra-operative and post-operative measurements. To assist the clinician while acquiring bony anatomical landmarks, the extraction of the bone---soft tissue interface and bony landmarks from ultrasound images is done automatically. The experimentations were performed on a database of images from healthy volunteers, and the obtained results showed the efficiency and the stability of the performance of the proposed method.

Minimally invasive registration for computer-assisted orthopedic surgery: combining tracked ultrasound and bone surface points via the P-IMLOP algorithm.

We present a registration method for computer-assisted total hip replacement (THR) surgery, which we demonstrate to improve the state of the art by both reducing the invasiveness of current methods and increasing registration accuracy. A critical element of computer-guided procedures is the determination of the spatial correspondence between the patient and a computational model of patient anatomy. The current method for establishing this correspondence in robot-assisted THR is to register points intraoperatively sampled by a tracked pointer from the exposed proximal femur and, via auxiliary incisions, from the distal femur. In this paper, we demonstrate a noninvasive technique for sampling points on the distal femur using tracked B-mode ultrasound imaging and present a new algorithm for registering these data called Projected Iterative Most-Likely Oriented Point (P-IMLOP). Points and normal orientations of the distal bone surface are segmented from ultrasound images and registered to the patient model along with points sampled from the exposed proximal femur via a tracked pointer. The proposed approach is evaluated using a bone- and tissue-mimicking leg phantom constructed to enable accurate assessment of experimental registration accuracy with respect to a CT-image-based model of the phantom. These experiments demonstrate that localization of the femur shaft is greatly improved by tracked ultrasound. The experiments further demonstrate that, for ultrasound-based data, the P-IMLOP algorithm significantly improves registration accuracy compared to the standard ICP algorithm. Registration via tracked ultrasound and the P-IMLOP algorithm has high potential to reduce the invasiveness and improve the registration accuracy of computer-assisted orthopedic procedures.

Numerical optimization of alignment reproducibility for customizable surgical guides.

PurposeComputer-assisted orthopedic surgery aims at minimizing invasiveness, postoperative pain, and morbidity with computer-assisted preoperative planning and intra-operative guidance techniques, of which camera-based navigation and patient-specific templates (PST) are the most common. PSTs are one-time templates that guide the surgeon initially in cutting slits or drilling holes. This method can be extended to reusable and customizable surgical guides (CSG), which can be adapted to the patients’ bone. Determining the right set of CSG input parameters by hand is a challenging task, given the vast amount of input parameter combinations and the complex physical interaction between the PST/CSG and the bone.MethodsThis paper introduces a novel algorithm to solve the problem of choosing the right set of input parameters. Our approach predicts how well a CSG instance is able to reproduce the planned alignment based on a physical simulation and uses a genetic optimization algorithm to determine optimal configurations. We validate our technique with a prototype of a pin-based CSG and nine rapid prototyped distal femora.ResultsThe proposed optimization technique has been compared to manual optimization by experts, as well as participants with domain experience. Using the optimization technique, the alignment errors remained within practical boundaries of 1.2 mm translation and 0.9^circ rotation error. In all cases, the proposed method outperformed manual optimization.ConclusionsManually optimizing CSG parameters turns out to be a counterintuitive task. Even after training, subjects with and without anatomical background fail in choosing appropriate CSG configurations. Our optimization algorithm ensures that the CSG is configured correctly, and we could demonstrate that the intended alignment of the CSG is accurately reproduced on all tested bone geometries.

Three-dimensional virtual bone bank system for selecting massive bone allograft in orthopaedic oncology.

Although structural bone allografts have been used for years to treat large defects caused by tumour or trauma, selecting the most appropriate allograft is still challenging. The objectives of this study were to: (1) describe the establishment of a visual bone bank system and workflow of allograft selection, and (2) show mid-term follow-up results of patients after allograft implantation. Allografts were scanned and stored in Digital Imaging and Communications in Medicine (DICOM) files. Then, image segmentation was conducted and 3D model reconstructed to establish a visual bone bank system. Based on the volume registration method, allografts were selected after a careful matching process. From November 2010 to June 2013, with the help of the Computer-assisted Orthopaedic Surgery (CAOS) navigation system, the allografts were implanted in 14 patients to fill defects after tumour resection. By combining the virtual bone bank and CAOS, selection time was reduced and matching accuracy was increased. After 27.5 months of follow-up, the mean Musculoskeletal Tumor Society (MSTS) 93 functional score was 25.7 ± 1.1 points. Except for two patients with pulmonary metastases, 12 patents were alive without evidence of disease at the time this report was written. The virtual bone bank system was helpful for allograft selection, tumour excision and bone reconstruction, thereby improving the safety and effectiveness of limb-salvage surgery.