Computer-assisted Orthopaedic Surgery Systems Research Articles

A review of computer-assisted orthopaedic surgery systems.

Computer-assisted orthopaedic surgery systems have great potential, but no review has focused on computer-assisted surgery systems for the spine, hip, and knee. A systematic search was performed in Web of Science and PubMed. We searched the literature on computer-assisted orthopaedic surgery systems from 2008 to the present and focused on three aspects of systems: training, planning, and intraoperative navigation. In this review study, we reviewed 34 surgical training systems, 31 surgical planning systems, and 41 surgical navigation systems. The functions and characteristics of the surgical systems were compared and analysed, and the current concerns about and the impact of the surgical systems on doctors and surgery were clarified. Computer-assisted orthopaedic surgery systems are still in the development stage. Future surgical training systems should include synthetic models with patient anatomy. Surgical planning systems with automatic planning should be developed, and surgical navigation systems with multimodal fusion, robotic assistance and imaging should be developed.

The Use of Precision Alignment Technology to Circumvent Patient- Specific Roadblocks in Performing Total Knee Arthroplasty

The goal of total knee arthroplasty (TKA) is to provide the patient with a well-functioning, pain-free knee that will last for many years. To improve implant survival, the goal is to position the prosthesis in a way that restores proper biomechanical alignment, and advances in technology have enabled arthroplasty surgeons to produce accurate results on a more consistent basis. One of these advances is the use of computer-assisted orthopaedic surgery (CAOS) to assist in proper component alignment and produce accurate restoration of the biomechanical axis consistently.1–17 Functional scores and revision-free survival are at least equivalent to conventional arthroplasty.17–26 Traditional cutting guides for TKA rely on intramedullary femoral instruments, and either intramedullary or extramedullary tibial instruments, to obtain proper axial alignment. In cases where retained hardware is present, or in patients with knee osteoarthritis associated with pre-existing femoral or tibial extra-articular deformity, CAOS has proved to be an exceptionally useful, effective, and appealing option.27–37 A portable, accelerometer-based navigation device (OrthAlign, OrthAlign Inc., Aliso Viejo, CA) for TKA has demonstrated promising results with regard to the alignment accuracy of large-console CAOS systems.10–14 We present three patients who underwent TKA with retained femoral hardware. Two patients had intramedullary femoral fixation and one patient had an interference screw from a previous anterior cruciate ligament (ACL) reconstruction that would interfere with the use of a conventional intramedullary alignment guide. A novel, portable, accelerometer-based navigation (OrthAlign® precision alignment system, OrthAlign Inc., Aliso Viejo, CA) guide enabled performance of TKA without the need for surgical removal of hardware.

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.

Preoperative trajectory planning for closed reduction of long-bone diaphyseal fracture using a computer-assisted reduction system

Balancing reduction accuracy with soft-tissue preservation is a challenge in orthopaedics. Computer-assisted orthopaedic surgery (CAOS) can improve accuracy and reduce radiation exposure. However, previous reports have not summarized the fracture patterns to which CAOS has been applied. We used a CAOS system and a stereolithography model to define a new fracture classification. Twenty reduction tests were performed to evaluate the effectiveness of preoperative trajectory planning. Twenty tests ran automatically and smoothly. Only three slight scratches occurred. Seventy-six path points represented displacement deviations of < 2 mm (average < 1 mm) and angulation deviation of < 1.5°. Because of the strength of muscles, mechanical sensors are used to prevent iatrogenic soft-tissue injury. Secondary fractures are prevented mainly through preoperative trajectory planning. Based on our data, a 1 mm gap between the edges of fractures spikes is sufficient to avoid emergency braking from spike interference.

Computer-Assisted Orthopaedic Surgery and Robotic Surgery in Total Hip Arthroplasty

Various systems of computer-assisted orthopaedic surgery (CAOS) in total hip arthroplasty (THA) were reviewed. The first clinically applied system was an active robotic system (ROBODOC), which performed femoral implant cavity preparation as programmed preoperatively. Several reports on cementless THA with ROBODOC showed better stem alignment and less variance in limb-length inequality on radiographic evaluation, less incidence of pulmonary embolic events on transesophageal cardioechogram, and less stress shielding on the dual energy X-ray absorptiometry analysis than conventional manual methods. On the other hand, some studies raise issues with active systems, including a steep learning curve, muscle and nerve damage, and technical complications, such as a procedure stop due to a bone motion during cutting, requiring re-registration and registration failure. Semi-active robotic systems, such as Acrobot and Rio, were developed for ease of surgeon acceptance. The drill bit at the tip of the robotic arm is moved by a surgeon's hand, but it does not move outside of a milling path boundary, which is defined according to three-dimensional (3D) image-based preoperative planning. However, there are still few reports on THA with these semi-active systems. Thanks to the advancements in 3D sensor technology, navigation systems were developed. Navigation is a passive system, which does not perform any actions on patients. It only provides information and guidance to the surgeon who still uses conventional tools to perform the surgery. There are three types of navigation: computed tomography (CT)-based navigation, imageless navigation, and fluoro-navigation. CT-based navigation is the most accurate, but the preoperative planning on CT images takes time that increases cost and radiation exposure. Imageless navigation does not use CT images, but its accuracy depends on the technique of landmark pointing, and it does not take into account the individual uniqueness of the anatomy. Fluoroscopic navigation is good for trauma and spine surgeries, but its benefits are limited in the hip and knee reconstruction surgeries. Several studies have shown that the cup alignment with navigation is more precise than that of the conventional mechanical instruments, and that it is useful for optimizing limb length, range of motion, and stability. Recently, patient specific templates, based on CT images, have attracted attention and some early reports on cup placement, and resurfacing showed improved accuracy of the procedures. These various CAOS systems have pros and cons. Nonetheless, CAOS is a useful tool to help surgeons perform accurately what surgeons want to do in order to better achieve their clinical objectives. Thus, it is important that the surgeon fully understands what he or she should be trying to achieve in THA for each patient.

Intra- and extra-articular planes of reference for use in total hip arthroplasty: a preliminary study.

Acetabular component malalignment in total hip arthroplasty can lead to potential complications such as dislocation, component impingement and excessive wear. Computer-assisted orthopaedic surgery systems generally use the anterior pelvic plane (APP). Our aim was to investigate the reliability of anatomical landmarks accessible during surgery and to define new potential planes of reference. Three types of palpations were performed: virtual, on dry bones and on two cadaveric specimens. Four landmarks were selected, the reproducibility of their positioning ranging from 0.9 to 2.3 mm. We then defined five planes and tested them during palpations on two cadaveric specimens. Two planes produced a mean orientation error of 5.0° [standard deviation (SD 3.3°)] and 5.6° (SD 2.7°). Even if further studies are needed to test the reliability of such planes on a larger scale in vivo during surgery, these results demonstrated the feasibility of defining a new plane of reference as an alternative to the APP.

Novel 3D hexapod computer‐assisted orthopaedic surgery system for closed diaphyseal fracture reduction

Long-bone fractures are very common in trauma centers. The conventional Arbeitsgemeindschaft fur Osteosynthesefragen (AO) technique contributes to most fracture healing problems, and external fixation technology also has several disadvantages, so new techniques are being explored. A novel hexapod computer-assisted fracture reduction system based on a 3D-CT image reconstruction process is presented for closed reduction of long-bone diaphyseal fractures. A new reduction technique and upgraded reduction device are described and the whole system has been validated. Ten bovine femoral fracture models were used with random fracture patterns. Tests results were as follows: residual deviation 1.24 + 0.65 mm for the axial deflection, 1.19 + 0.37 mm for the translation, 2.34 + 1.79° for the angulation, and 2.83 + 0.9° for the rotation. The reduction mechanism has the advantages of high positioning, reduction and computer accuracy, and intra-operative stability for both patients and surgical team. With further investigation, it could be applied in many kinds of long-bone diaphyseal fractures.

Measuring the positional accuracy of computer assisted surgical tracking systems

Computer Assisted Orthopaedic Surgery (CAOS) technology is constantly evolving with support from a growing number of clinical trials. In contrast, reports of technical accuracy are scarce, with there being no recognized guidelines for independent measurement of the basic static performance of computer assisted systems. To address this problem, a group of surgeons, academics and manufacturers involved in the field of CAOS collaborated with the American Society for Testing and Materials (ASTM) International and drafted a set of standards for measuring and reporting the technical performance of such systems. The aims of this study were to use these proposed guidelines in assessing the positional accuracy of both a commercially available and a novel tracking system.A standardized measurement object model based on the ASTM guidelines was designed and manufactured to provide an array of points in space. Both the Polaris camera with associated active infrared trackers and a novel system that used a small visible-light camera (MicronTracker) were evaluated by measuring distances and single point repeatability. For single point registration the measurements were obtained both manually and with the pointer rigidly clamped to eliminate human movement artifact.The novel system produced unacceptably large distance errors and was not evaluated beyond this stage. The commercial system was precise and its accuracy was well within the expected range. However, when the pointer was held manually, particularly by a novice user, the results were significantly less precise by a factor of almost ten.The ASTM guidelines offer a simple, standardized method for measuring positional accuracy and could be used to enable independent testing of tracking systems. The novel system demonstrated a high level of inaccuracy that made it inappropriate for clinical testing. The commercially available tracking system performed well within expected limits under optimal conditions, but revealed a surprising loss of accuracy when movement artifacts were introduced. Technical validation of systems may give the user community more confidence in CAOS systems as well as highlighting potential sources of point registration error.

Understanding and analysis of CAOS development in context: the case of China

Computer-assisted orthopaedic surgery (CAOS) has great advantages in precise determination of focus, planning an optimal surgical project and assuring the success of operation. In adopting CAOS, China is facing many problems, gaining experience and learning lessons. A literature review of the current development of CAOS in China and case studies, including adopted CAOS systems, CAOS clinical applications in the orthopaedic field and emerging CAOS research in China was carried out. Experience and lessons gained through adopting CAOS in China are also illustrated and analysed. In the course of investigating the current development of CAOS in China, existing problems were analysed, experience gained and lessons illustrated. By summarizing the Chinese experience and lessons of adopting CAOS, we not only deliver an in-depth understanding of present CAOS development and give advice for future CAOS development in China; this also has implications for other developing countries where CAOS development is burgeoning.

CompAS: A new approach to commonality and variability analysis with applications in computer assisted orthopaedic surgery

In rapidly evolving domains such as Computer Assisted Orthopaedic Surgery (CAOS) emphasis is often put first on innovation and new functionality, rather than in developing the common infrastructure needed to support integration and reuse of these innovations. In fact, developing such an infrastructure is often considered to be a high-risk venture given the volatility of such a domain. We present CompAS, a method that exploits the very evolution of innovations in the domain to carry out the necessary quantitative and qualitative commonality and variability analysis, especially in the case of scarce system documentation. We show how our technique applies to the CAOS domain by using conference proceedings as a key source of information about the evolution of features in CAOS systems over a period of several years. We detect and classify evolution patterns to determine functional commonality and variability. We also identify non-functional requirements to help capture domain variability. We have validated our approach by evaluating the degree to which representative test systems can be covered by the common and variable features produced by our analysis.

Computer assisted orthopedic surgery; its influence on prosthesis size in total knee replacement

Improvement of alignment and position of the components in TKAs using Computer Assisted Orthopaedic Surgery (CAOS) has been described. However, much less is known about the accuracy of CAOS in determining the size of the components. The purpose of this study was to evaluate the size of the femoral and tibial component using the CAOS system from Brainlab. The component sizes were compared to pre-operative templating and post-operative scoring the adequateness of size. Forty TKAs (NexGen) were evaluated: 20 using CAOS and 20 conventional. Statistical analysis of the templated and implanted size indicated a fair agreement for the femur (kappa 0.38) and the tibia (kappa 0.35). In the CAOS group significantly more oversizing occurred for the femoral component ( p = 0.020). No significant difference was found for the tibial component. We conclude there is a risk of oversizing the femoral component of the NexGen system when using CAOS.

(ii) The accuracy of surgical navigation for orthopaedic surgery

Summary The ability to place accurately and consistently a tool or implant in orthopaedic surgery is potentially one of the key benefits of using a computer assisted orthopaedic surgery (CAOS) system. To achieve such accuracy CAOS systems are considerably more complex in their design than conventional surgical tools. CAOS systems typically comprise patient data acquisition, computer based planning and a means to help the surgeon carry out the surgical plan. Each of these elements can give rise to inaccuracies which propagate through following workflow elements to contribute to the accuracy of the clinical outcome. This paper discusses the nature of accuracy, where inaccuracies occur in CAOS systems and how a structured approach to validation helps provide CAOS systems that perform reliably. It is clearly important that surgeons are fully aware of all factors at the interfaces between the surgeon and the patient and a CAOS system that might affect the accuracy of the clinical outcome.

Cup Alignment Error Model for Total Hip Arthroplasty

Almost all computer-assisted orthopaedic surgery systems that rely on the anterior pelvic plane definition, such as in computed tomography and magnetic resonance image-based, fluoroscopy-based, and nonimage total hip replacement approaches, are derived from identifying two pairs of pelvic bony landmarks: anterior superior iliac spines and the pubic tubercles. Although these systems strive to achieve cup alignment accuracy of approximately 1 degree, even a minor failure to correctly identify these anatomic landmarks can lead to higher inaccuracies in the final cup alignment. This study shows how to examine the effects of these inaccuracies on the final acetabular cup implant orientation during total hip replacement by generating a kinematic model, which then is simulated. Simulation results indicate that, for example, a total error of 4 mm in measuring the anterior superior iliac spine and the pubic tubercles would result in a final cup orientation of 47 degrees and 27 degrees in abduction and version respectively, resulting in a 2 degrees abduction error and 7 degrees error in version when targeting 45 degrees abduction and 20 degrees version results. These calculations can be repeated for any error values.

Design and experimental study of computer-assisted orthopaedic system for distal locking of intramedullary nails

To test the safety and accuracy of the computer-assisted orthopaedic system for distal locking of intramedullary nails and apply it to internal fixation with intramedullary nails in the lower limb. According to the theory of mechanical arms stereotactic localization in computer-assisted orthopaedic surgery (CAOS), we design a CAOS system for distal locking of intramedullary nails. The system comprised 2 independent modules: computer-assisted imaging and registration workstation; mechanical stereotactic framework. Ten plastic tibia models, 20 plastic femur models (Synbone AG, Malans, Switzerland) and 6 human cadaver lower limbs were randomly divided into 2 groups undergoing internal fixation with intramedullary nails (Orthofix, Germany). The first group (CAOS group with 5 plastic tibia models, 10 plastic femur models, 6 human cadaver tibia, 6 human cadaver femur; each nail had 2 holes, and 2 distal locking screws were inserted in each bone, which gave a total number of 54 holes) used a computer-assisted orthopaedic system, the second group (CONTROL GROUP is the same as CAOS group) used Orthofix mechanical targeting device for distal locking. Comparison between 2 groups was made in radiation exposure time, operating time, percentage of correctly placed screws. CAOS group: operating time was (4.44 +/- 2.99) min; radiation exposure time was (1.16 +/- 0.38) min; correctly placed screws rate was (100 +/- 0)%. operating time was (10.42 +/- 4.18) min; radiation exposure time was (4.71 +/- 3.86) min; correctly placed screws rate was (94.44 +/- 0.36)%. Operating time and radiation exposure time in CAOS group were significantly shorter than those in control group (P < 0.05), no differences were found between 2 groups in relation to the percentage of correctly placed screws. By using CAOS system for distal locking of intramedullary nails, the locking holes can be drilled accurately and safely. Radiation exposure significantly reduced.

Paper #67 The use of CAOS (Computer Assisted Orthopaedic Surgery System) to evaluate the intra- and the inter-surgeon reliability in tunnel placement for ACL reconstruction

Objectives1) To evaluate surgeon reliability in tunnel placement for ACL reconstruction with the use of the CAOS system; and 2) to evaluate the efficiency of CAOS to assist the surgeon with tunnel position.BackgroundThe success of anterior cruciate ligament reconstruction depends upon the correct placement of tibial and femoral tunnels. Failures are usually due to mal-position of the tibial and / or femoral tunnels.Design/methodsA standard arthroscopic approach was performed in three cadaver knees and 14 surgeons (5 orthopaedic fellows, 5 general orthopaedic surgeons and 4 knee surgeons) were asked to place femoral and tibial tunnels. They, then, placed femoral and tibial tunnels with the use of the CAOS system. All the points were recorded and compared to tibial and femoral reference points (from the ideal graft) using a data processing software on Matlab.ResultsIntra-surgeon reproducibility was 1.1 mm on the femur and 1.4 mm on the tibia. The mean variability was 3.1 (1.4) mm and 3.4 (0.8) mm. The inter-surgeon variability was 6.3 (3) mm on the femur and 5.6 (1.6) mm on the tibia.ConclusionsIntra-surgeon reproducibility is good, but variability is high which is a concern as regards clinical consequences. The inter-surgeon variability is great and depends upon experience. The CAOS system allows a more precise placement on the femur, and on the tibia only in the medio-lateral axis. Objectives1) To evaluate surgeon reliability in tunnel placement for ACL reconstruction with the use of the CAOS system; and 2) to evaluate the efficiency of CAOS to assist the surgeon with tunnel position. 1) To evaluate surgeon reliability in tunnel placement for ACL reconstruction with the use of the CAOS system; and 2) to evaluate the efficiency of CAOS to assist the surgeon with tunnel position. BackgroundThe success of anterior cruciate ligament reconstruction depends upon the correct placement of tibial and femoral tunnels. Failures are usually due to mal-position of the tibial and / or femoral tunnels. The success of anterior cruciate ligament reconstruction depends upon the correct placement of tibial and femoral tunnels. Failures are usually due to mal-position of the tibial and / or femoral tunnels. Design/methodsA standard arthroscopic approach was performed in three cadaver knees and 14 surgeons (5 orthopaedic fellows, 5 general orthopaedic surgeons and 4 knee surgeons) were asked to place femoral and tibial tunnels. They, then, placed femoral and tibial tunnels with the use of the CAOS system. All the points were recorded and compared to tibial and femoral reference points (from the ideal graft) using a data processing software on Matlab. A standard arthroscopic approach was performed in three cadaver knees and 14 surgeons (5 orthopaedic fellows, 5 general orthopaedic surgeons and 4 knee surgeons) were asked to place femoral and tibial tunnels. They, then, placed femoral and tibial tunnels with the use of the CAOS system. All the points were recorded and compared to tibial and femoral reference points (from the ideal graft) using a data processing software on Matlab. ResultsIntra-surgeon reproducibility was 1.1 mm on the femur and 1.4 mm on the tibia. The mean variability was 3.1 (1.4) mm and 3.4 (0.8) mm. The inter-surgeon variability was 6.3 (3) mm on the femur and 5.6 (1.6) mm on the tibia. Intra-surgeon reproducibility was 1.1 mm on the femur and 1.4 mm on the tibia. The mean variability was 3.1 (1.4) mm and 3.4 (0.8) mm. The inter-surgeon variability was 6.3 (3) mm on the femur and 5.6 (1.6) mm on the tibia. ConclusionsIntra-surgeon reproducibility is good, but variability is high which is a concern as regards clinical consequences. The inter-surgeon variability is great and depends upon experience. The CAOS system allows a more precise placement on the femur, and on the tibia only in the medio-lateral axis. Intra-surgeon reproducibility is good, but variability is high which is a concern as regards clinical consequences. The inter-surgeon variability is great and depends upon experience. The CAOS system allows a more precise placement on the femur, and on the tibia only in the medio-lateral axis.

Computer-Assisted Orthopaedic Surgery

Summary To precisely realize a preoperative plan during an intraoperative intervention, neurosurgeons developed stereotactic approaches as early as the beginning of the last century. However, their concepts lacked accuracy as a result of the absence of appropriate imaging methods and three-dimensional tracking devices. With the availability of these technologies, computer-aided surgery was invented and eventually found its way into the orthopaedic operating rooms. This article describes this historical development and gives an overview of current applications and techniques. It lists major unsolved problems of computer-assisted orthopaedic surgery (CAOS) and discusses solutions that have been proposed. During this review, navigation systems based on preoperative computed tomography scans, intraoperative fluoroscopy images, and interactively digitized structures are presented, and their differences and commonalities are elucidated. The article explains the technical background of the different approaches as well as special elements of the pre- and intraoperative use of CAOS systems. To bridge theory and practice, examples for a variety of clinical applications are provided such as spinal stabilization, pelvic osteotomies, total hip replacement, total knee replacement, anterior cruciate ligament replacement, and fracture treatment.