Fluoroscopy-based Navigation System Research Articles

Percutaneous screw fixation of acetabular fractures with 2D fluoroscopy-based computerized navigation

The treatment of displaced acetabular fractures with formal open reduction and internal fixation has gained general acceptance. However, extensile exposure can lead to complications. Two-dimensional fluoroscopy-based computerized navigation for placement of percutaneous screw across non-displaced acetabular fractures has attracted interest by making use of stored patient-specific imaging data to provide real-time guidance in multiple image planes during implant placement. The purpose of the present study was to document early treatment results and complications associated with this new technique and evaluate its clinical application to displaced acetabular fractures amenable to closed or limited open reduction. Eighteen adult patients with 12 non-displaced and 8 displaced acetabular fractures were treated with percutaneous screw fixation under the guidance of a fluoroscopy-based navigation system. There were 14 men and four women with a mean age of 42.1 years (range 19-54 years). According to the AO and Orthopaedic Trauma Association Classification, there were nine 62-A3, five 62-B1, three 62-B2, and three 62-B3. The mean follow-up was 21 months (range 12-28 months). The mean time from injury to surgery was 4 days (range 2-7 days). A total of 30 acetabular screws were inserted, including 21 anterior column screws and 9 posterior column screws. The average operation time was 24.6 min (range 16-47 min) from the image acquisition to wound closure. The average fluoroscopic time was 28.4 s (range 11-58 s). Compared to the final position of the screw, the average deviated distance of wire tip was 2.5 mm (range 1.1-3.6 mm) and the average trajectory difference was 2.45 degrees (range 1.5 degrees -4.6 degrees ). Maximal gap displacement averaged 10 mm (range 2-22 mm) preoperatively and 3 mm (range 0-5 mm) postoperatively; while maximal step displacement averaged 4 mm (range 1-10 mm) preoperatively and 2 mm (range 0-4 mm) postoperatively. One patient sustained a transient femoral nerve palsy and resolved 2 months after the operation. No superficial or deep infection occurred. Using the rating system of D'Aubigne and Postel, 13 patients had excellent results, 4 patients had good results, and 1 patient had a fair result. Percutaneous screw fixation of acetabular fractures with 2D fluoroscopy-based navigation could be applied not only to non-displaced fractures but also to displaced fractures amenable to closed or limited open reduction.

Evaluation of a new fluoroscopy-based navigation system in the placement of the femoral component in hip resurfacing

Prosthesis-specific mechanical alignment instruments for the precise and reproducible positioning of the femoral component constitute one of the major improvements in modern hip resurfacing prostheses. However, mechanical failure of the femoral component is mostly attributable to the surgical technique, and in particular to notching of the femoral neck. In order to evaluate a novel computer-assisted fluoroscopy-based planning and navigation system, six DUROM hip resurfacing prostheses were implanted into artificial femurs by means of computer-assisted fluoroscopy-based navigation and prosthesis-specific mechanical alignment instruments. Subsequently, the planning and navigation system was tested within the scope of a cadaver study on three fixed whole-body preparations (six femurs). The average difference between planned and actual angle of the prosthesis was 0 +/- 0.7 degrees for fluoroscopy-based navigation versus 6.5 +/- 7.8 degrees for the in-vitro use of the prosthesis-specific mechanical alignment instruments, and 1 +/- 1.4 degrees for fluoroscopic navigation in the cadaver study. The average discrepancy between planned and actual anterior offset was -1.2 +/- 1.2 mm versus 0.8 +/- 4 mm, and 0.3 +/- 2.2 mm in the cadaver study, and the time required for the total of five planning and navigation steps was 17.2 +/- 1.5 min versus 14 +/- 0.8 min and 20.2 +/- 2.5 min respectively. No notching of the femoral neck occurred under fluoroscopy nor under conventional treatment. During in-vitro studies, use of the computer-assisted fluoroscopy-based planning and navigation system resulted in enhanced accuracy compared with conventional prosthesis-specific mechanical alignment instruments. The system has yielded initial promising results within the scope of the cadaver study.

Percutaneous screwing for unstable pelvic fractures with fluoroscopy-bused computerized navigation

Objective To discuss operative indications and clinical outcomes of the fluo-roscopy-based computerized navigational system for unstable pelvic fractures. Methods From August 2006 to September 2008, 16 patients with unstable pelvic fractures were treated with pereutaneous screwing under a fluoroscopy-based computer navigation system. According to Tile classification, 2 cases were type B2,3 type B3, 8 type C2, and 3 type C3. Navigated pereutaneons screwing included 26 sacroiliac screws in 14 eases, 15 superior ramus medullary screws in 9 cases, 4 pubic symphysis screws in 4 cases, and 2 anterior column screws in 2 cases. Accuracy of screw placement was verified by radiography and CT scan. Mean time of percutaneous screw implantation and intra-operative fluoroscopic time were recorded for each type to evaluate the procedure. Results Eleven patients were followed up for 119.6 ± 2.3 d. The mean time of bone healing was 67.7 ± 9.7 d. All screws were placed accurately without perforating the cortex. Expect a little numbness in the lower extremities in 3 patients, no eomplication was noted postoperatively. The mean time of navigated screw implantation was 26. 39 ± 6. 23 min for sacroiliac screw, 18.20 ± 1.59 min for superior ramus medullary screw, 13.70 ± 2.13 min for pubic symphysis screw implantation, and 19.40 ± 0.79 min for an-terior column screw. The mean time of intra-operative fluoroscopy was 0. 57 ± 0. 03 min for sacroiliac screw,0.61±0.13 min for superior ramus medullary screw, 0.33±0.06 min for pubic symphysis screw, and 0.63 ± 0.02 min for anterior column screw. Conclusions Percutaneous sacroiliac screwing, superior ramus medullary screwing, pubic symphysis screwing can be performed with assistance of fluoroscopy-based computerized navigation for the treatment of unstable peivie fractures. Though the indications for this procedure are limited, we think it should be applied due to its advantages of less radiation, higher accuracy and greater reliability. Key words: Pelvis; Fractures; Surgery, computer-assisted; Fracture fixation, internal

Long bone fracture reduction using a fluoroscopy-based navigation system: A feasibility and accuracy study

Long bone fracture reduction using a fluoroscopy-based navigation system: A feasibility and accuracy study

Fluoroscopy-based navigation system in spine surgery

The variability in width, height, and spatial orientation of a spinal pedicle makes pedicle screw insertion a delicate operation. The aim of the current paper is to describe a computer-assisted surgical navigation system based on fluoroscopic X-ray image calibration and three-dimensional optical localizers in order to reduce radiation exposure while increasing accuracy and reliability of the surgical procedure for pedicle screw insertion. Instrumentation using transpedicular screw fixation was performed: in a first group, a conventional surgical procedure was carried out with 26 patients (138 screws); in a second group, a navigated surgical procedure (virtual fluoroscopy) was performed with 26 patients (140 screws). Evaluation of screw placement in every case was done by using plain X-rays and post-operative computer tomography scan. A 5 per cent cortex penetration (7 of 140 pedicle screws) occurred for the computer-assisted group. A 13 per cent penetration (18 of 138 pedicle screws) occurred for the non computer-assisted group. The radiation running time for each vertebra level (two screws) reached 3.5 s on average in the computer-assisted group and 11.5 s on average in the non computer-assisted group. The operative time for two screws on the same vertebra level reaches 10 min on average in the non computer-assisted group and 11.9 min on average in the computer-assisted group. The fluoroscopy-based (two-dimensional) navigation system for pedicle screw insertion is a safe and reliable procedure for surgery in the lower thoracic and lumbar spine.

Automated detection and segmentation of cylindrical fragments from calibrated C-arm images for long bone fracture reduction

Long bone fracture belongs to one of the most common injuries encountered in clinical routine trauma surgery. Automated identification, pose and size estimation, and contour extraction of diaphyseal bone fragments can greatly improve the usability of a computer-assisted, fluoroscopy-based navigation system for long bone fracture reduction. In this paper, a two-step solution is proposed. In the first step, the pose and size of a diaphyseal fragment are estimated through a three-dimensional (3D) morphable object-based fitting process using a parametric cylinder model. This fitting process is optimally solved by a hybrid optimization technique coupling a random sample consensus (RANSAC) paradigm and an iterative closest point (ICP) matching procedure. Monte Carlo simulation was used to determine the parameters for the RANSAC paradigm. The results of the fragment detection step are then fed to the second step, where a region information based active contour model is used to extract the fragment contours. We designed and conducted experiments to quantify the accuracy and robustness of the proposed approach. Our experimental results conducted on images of a plastic bone as well as on those of patients demonstrate a promising accuracy and robustness of the proposed approach.

Arthroscopic anterior cruciate ligament reconstruction guided by fluoroscopy-based navigation system

To introduce the process and outline of fluoroscopy-based navigation system assisted anterior cruciate ligament (ACL) reconstruction, and evaluate its feasibility and accuracy. From September 2005 to February 2006, there were 30 cases ACL rupture patients who received fluoroscopy-based navigation system assisted arthroscopy operations for ACL reconstruction (navigation group). At the same time, there were 40 patients who underwent traditional ACL operation (traditional group). For the navigation group, the proper placement of femoral and tibial tunnels was planned preoperatively in standard AP and lateral X-ray view. Intraoperative fluoroscopic images were taken and input into navigation computer system to form the virtual interactive working fields. After placement and registration, signals from patient trackers, which fixed on the distal femur and tibia respectively, and tool trackers, which attached with ACL tibial and femoral guide, were captured by the optic navigation camera and the navigation computer system could pursue the real-time position of the ACL tools and projected into working field to help precise placement of femoral and tibial tunnels. Then results of two groups were observed and evaluated. For navigation group, the mean time extension was 20 min. The tibial tunnel position was measured in all these cases. The tibial tunnel position of navigation group was 45.90% (SD 2.36%), and the traditional group was 41.05% (SD 6.01%). The difference was statistically significant (P < 0.05). Fluoroscopy-based navigation system assisted ACL reconstruction improves the accuracy and reproducibility of the tunnel placement.

Long bone fracture reduction using a fluoroscopy-based navigation system: A feasibility and accuracy study

Objective: Long bone fracture reduction during intramedullary nailing can result in a small but significant rate of angular and rotational malalignment, which can in turn lead to long-term morbidity. Current techniques for intraoperative reduction rely heavily on fluoroscopy, and their reproducibility can be limited. We suggest that fluoroscopy-based navigation may improve the precision of long bone fracture reduction and reduce radiation exposure.Methods: A cadaveric tibia was stripped of soft tissues and fractured at its midline. The ends were then cemented to two mobile brackets within a fracture/deformity simulator. Optical trackers were drilled into each fragment. Radiographs were obtained including AP and lateral views of the proximal and distal ends of the bone as well as the fracture site. These radiographs were stored in the computer navigation system. Fracture reduction was performed using a fluoroscopy-based navigation system with virtual intraoperative planning software. The system used 4 sets of lines drawn by the surgeon on the fluoroscopic AP and lateral images. While navigating the reduction of the fracture these lines aligned together, providing graphic and numerical descriptions of the reduction. The lines included the anatomic axis of the bone, the matching of the fracture lines, the short segment anatomic axis (near the fracture site), and the AP mid-sagittal joint line (MSJL) of both the plateau and the plafond. Anatomic reduction was then performed and the computer assessment of the angulation and translation of the fragments was recorded. Each stage was repeated 25 times for each set of lines. For the control group the surface of the bone was tracked using an optical probe.Results: The accuracy of the system varied according to the planning method. The most accurate technique was matching of the fracture lines, which yielded 2.68 ± 1.18 mm of translation and 2.5 ± 1.27° of angulation. The next most accurate method was using the short segment anatomic axis, followed by using the anatomic axis method. The control group was the most accurate (1.78 ± 0.67 mm translation, 1.58 ± 0.97° angulation). The AP MSJL yielded errors greater than 10°.Conclusions: Fluoroscopy-based navigation is sufficiently accurate for long bone fracture reduction, potentially increasing angular and translational accuracy while reducing the amount of intraoperative fluoroscopy. Navigation may improve the outcome of treatment of a long bone fracture by better restoring the normal mechanical axis of the limb in a less-invasive closed manner.

Computer-navigation assistance in arthroscopic reconstruction of anterior cruciate ligament

Objective To compare traditional arthroscopic reconstruction of anterior cruciate ligament (ACL) and the arthroscopic ACL reconstruction assisted by fluoroscopy-based navigation system in accuracy and reproducibility of the tunnel placement. Methods Fluoroscopy-based navigation system was used in 40 cases of arthroscopic ACL reconstruction from December 2005 to March 2006. Another 40 cases of traditional arthroscopic ACL reconstruction performed between June 2005 and March 2006 were used as control. The positions of the femoral and tibial tunnels were measured on their radiograms and compared statistically. Results The femoral tunnel position measurements averaged 62. 3%±5. 6% (52% - 73% ) in navigation-assisted ACL reconstruction, and 56. 6%±7. 3% (46% - 77% ) in the traditional arthroscopic operation. The tibial tunnel position measurements averaged 45.4%±3. 8% (37%-53% ) in the navigation-assisted ACL reconstruction, and 41. 1%±6. 0% (25% - 54% ) in the traditional arthroscopic operation. The differences were statistically significant ( P 0. 05). The mean operative duration for navigation-assisted ACL reconstruction was 20 minutes longer than that for traditional arthroscopic operation. Conclusion Arthroscopic ACL reconstruction assisted by fluoroscopy-based navigation system can improve the accuracy and reproducibility of the tunnel placement.

Navigated intraoperative analysis of lower limb alignment

Accurate intraoperative assessment of lower limb alignment is crucial for the treatment of long bone fractures, implantation of knee arthroplasties and correction of deformities. During orthopaedic surgery, exact real time control of the mechanical axis is strongly desirable. The aim of this study was to compare conventional intraoperative analysis of the mechanical axis by the cable method with continuous, 3-dimensional imaging with a navigation system. Twenty legs of fresh human cadaver were randomly assigned to conventional analysis with the cable method (n = 10) or navigated analysis with a fluoroscopy based navigation system (n = 10). The intersection of the mechanical axis with the tibia plateau was presented as percentage of the tibia plateau (beginning with 0% at the medial border and ending with 100% laterally). CT-scans were performed for all legs and the CT-values of the mechanical axis were compared to the measurements after cable method and navigation. Furthermore, the radiation time and dose area product of both groups for single analysis of the mechanical axis was compared. Conventional evaluation of the mechanical axis by the cable method showed 6.0+/-3.1% difference compared to the analysis by CT. In the navigated group the difference was 2.6+/-1.8% (P = 0.008). Radiation time and dose area product were highly significantly lower after conventional measurement. Navigated intraoperative evaluation of the mechanical axis offers increased accuracy compared to conventional intraoperative analysis. Furthermore, navigation provides continuous control not only of the mechanical axis, but also of the sagittal and transverse plane. Using the cable method, radiation exposure depends on the number of measurements and is lower compared to the navigation system for single intraoperative analysis of the mechanical axis, but may be higher in case of repeated intraoperative measurements.

Computer-assisted LISS plate osteosynthesis of proximal tibia fractures: Feasibility study and first clinical results

Fluoroscopy is the most common tool for the intraoperative control of long-bone fracture reduction. Limitations of this technology include high radiation exposure for the patient and the surgical team, limited visual field, distorted images, and cumbersome verification of image updating. Fluoroscopy-based navigation systems partially address these limitations by allowing fluoroscopic images to be used for real-time surgical localization and instrument tracking. Existing fluoroscopy-based navigation systems are still limited as far as the virtual representation of true surgical reality is concerned. This article, for the first time, presents a reality-enhanced virtual fluoroscopy with radiation-free updates of in situ surgical fluoroscopic images to control metaphyseal fracture reduction. A virtual fluoroscopy is created using the projection properties of the fluoroscope; it allows the display of detailed three-dimensional (3D) geometric models of surgical tools and implants superimposed on the X-ray images. Starting from multiple registered fluoroscopy images, a virtual 3D cylinder model for each principal bone fragment is constructed. This spatial cylinder model not only supplies a 3D image of the fracture, but also allows effective fragment projection recovery from the fluoroscopic images and enables radiation-free updates of in situ surgical fluoroscopic images by non-linear interpolation and warping algorithms. Initial clinical experience was gained during four tibia fracture fixations that were treated by LISS (Less Invasive Stabilization System) osteosynthesis. In the cases operated on, after primary image acquisition, the image intensifier was replaced by the virtual reality system. In all cases, the procedure including fracture reduction and LISS osteosynthesis was performed entirely in virtual reality. A significant disadvantage was the unfamiliar operation of this prototype software and the need for an additional operator for the navigation system.

Accuracy and potential pitfalls of fluoroscopy-guided acetabular cup placement

Using a total of 30 cadaveric hips, the accuracy of a fluoroscopy-based computer navigation system for cup placement in total hip arthroplasty (THA) was investigated and an error analysis was carried out. The accuracy of placing the acetabular component within a predefined safe zone using computer guidance was compared to the precision that could be achieved with a freehand approach. Accurate control measurements of the implanted cup were obtained using fiducial-based matching to a pre-operative CT scan with respect to the anterior pelvic plane. A significantly higher number of cups were placed in the safe zone with the help of the navigation system. The variability of cup placement could be reduced for cup abduction but not substantially for cup version. An error analysis of inaccurate landmark reconstruction revealed that the registration of the mid-pubic point with fluoroscopy was a potential source of error. Keeping this pitfall in mind, fluoroscopy-based navigation in THA is a useful tool for registration of the pelvic coordinate system, particularly those points that cannot be reached by direct pointer digitization with the patient in the lateral decubitus position.

Computer-Assisted Pedicle Screw Insertion

Summary Pedicle screw insertion is used for treatment of various disorders such as fractures, scoliosis, spondylolisthesis, or degenerative instabilities. With conventional procedures, there are between 10% and 40% of misplaced pedicle screws. Between 1998 and 2002, 2 navigation systems were used at the University Hospital of Grenoble (CHUG), France, for pedicle screw placement: a computed tomography (CT)-based and a fluoroscopy-based navigation system. Ninety-one patients were operated on with either systems, and 235 pedicle screws were inserted between T4 and L5 in 43 scoliosis and 48 fractures, spondylolisthesis, or degenerative instabilities. With the CT-based navigation system, 6.2% of the pedicle screws were misplaced (cortex penetration superior or equal to 2 mm). With the fluoroscopy-based navigation system, 14% of the pedicle screws were misplaced. The advantages of using a CT-based navigation system are there is no intraoperative x-ray radiation and you get real 3-D navigation views; the drawbacks are a preoperative CT scan is necessary and it requires time-consuming registration (2–10 min). The advantages of using a fluoroscopy-based navigation system are there is no preoperative imaging required, there is less radiation for both the patient and staff (as compared with conventional fluoroscopy), and no intraoperative registration is required (images are calibrated directly in patient reference system). The drawbacks are there is variable image quality and, most important for scoliosis cases, there are no real 3-D navigation views. Regarding the basic principle of computer-assisted surgery (CAS) systems, ie, multimodal data registration, some new technologies that are currently under development or testing are presented. The authors believe they will soon replace the existing data registration techniques (currently based on manual data collection directly on patient bone surface) in the next generation of CAS systems, mainly because of their increased accuracy and efficiency, but also because of easier implementation in the operating room. All of these new technologies should allow percutaneous pedicle screw placement or other type of spine surgery procedure (minimally invasive surgery) to be performed in the very near future.

Validation of fluoroscopy-based navigation in the hip region: what you see is what you get?

Fluoroscopy-based navigation systems can be used for internal fixation of intracapsular femoral neck fractures, with the object of optimizing positioning of the implant and reducing radiation exposure. With this technique, the virtual position and direction of a reamer can be simultaneously superimposed on anteroposterior (AP) and axial (AX) fluoroscopic images. However, surgeons have to rely on the accuracy of these systems, because the only intraoperative feedback on the true position of the reamer is the projection of a virtual reamer superimposed on two fluoroscopic images. The objective of this study was to evaluate the accuracy of the displayed position of the virtual reamer in relation to the true position of the instrument when using a fluoroscopy-based navigation system (medivision, Oberdorf, Switzerland). Secondary to this, the accuracy of the drill-channel measuring tool of the system was analyzed. The study was performed on 20 sawbones. To evaluate the position of the virtual reamer, an 8-mm Perspex bar was inserted in predefined drill channels in each sawbone. AP and AX fluoroscopic images of the sawbones with the Perspex bar were loaded into the workstation. The Perspex bar was then removed and exchanged for a navigated dynamic hip screw (DHS) reamer. The position of the Perspex bar in the images represented the true position of the reamer. Subsequently, the difference between the position of the virtual reamer and the Perspex bar was measured with a dedicated computer program. Drill-channel lengths measured with the system were compared with measurements obtained with a digital ruler. The mean difference in position of the Perspex bar and reamer at a predefined point was 0.90 mm (range: 0.00-3.21 mm) in 360 images. The mean difference in length measurements between the medivision system and the digital ruler was 1.00 mm (p = 0.01, SD =1.33). Reaming and measuring the screw channel of a DHS with a medivision fluoroscopy-based navigation system can be performed with an acceptable error margin.

Validation of Fluoroscopy-Based Navigation in the Hip Region: What you See is What you Get?

Fluoroscopy-based navigation systems can be used for internal fixation of intracapsular femoral neck fractures, with the object of optimizing positioning of the implant and reducing radiation exposure. With this technique, the virtual position and direction of a reamer can be simultaneously superimposed on anteroposterior (AP) and axial (AX) fluoroscopic images. However, surgeons have to rely on the accuracy of these systems, because the only intraoperative feedback on the true position of the reamer is the projection of a virtual reamer superimposed on two fluoroscopic images. The objective of this study was to evaluate the accuracy of the displayed position of the virtual reamer in relation to the true position of the instrument when using a fluoroscopy-based navigation system (medivision, Oberdorf, Switzerland). Secondary to this, the accuracy of the drill-channel measuring tool of the system was analyzed. The study was performed on 20 sawbones. To evaluate the position of the virtual reamer, an 8-mm Perspex bar was inserted in predefined drill channels in each sawbone. AP and AX fluoroscopic images of the sawbones with the Perspex bar were loaded into the workstation. The Perspex bar was then removed and exchanged for a navigated dynamic hip screw (DHS) reamer. The position of the Perspex bar in the images represented the true position of the reamer. Subsequently, the difference between the position of the virtual reamer and the Perspex bar was measured with a dedicated computer program. Drill-channel lengths measured with the system were compared with measurements obtained with a digital ruler. The mean difference in position of the Perspex bar and reamer at a predefined point was 0.90 mm (range: 0.00-3.21 mm) in 360 images. The mean difference in length measurements between the medivision system and the digital ruler was 1.00 mm (p = 0.01, SD = 1.33). Reaming and measuring the screw channel of a DHS with a medivision fluoroscopy-based navigation system can be performed with an acceptable error margin.