Computer-assisted Navigation Techniques Research Articles

Functional and Radiological Outcomes of All-Posterior Surgical Correction of Dystrophic Curves in Patients with Neurofibromatosis Type 1.

A retrospective cohort study. To determine outcomes following all-posterior surgery using computed tomography navigation, hybrid stabilization, and multiple anchor point techniques in patients with neurofibromatosis type 1 (NF-1) and dystrophic scoliosis. Previous studies favored antero-posterior fusion as the most reliable method; however, approaching the spine anteriorly was fraught with significant complications. With the advent of computer assisted navigation and multiple anchor point method, posterior only approach is reporting successful outcomes. This study included patients who underwent all-posterior surgical deformity correction for dystrophic NF-1 curves. Coronal and sagittal Cobbs angles, apical rotation, and the presence of dystrophic features were evaluated before surgery. Postoperatively, sagittal, coronal, and axial correction, implant position, and implant densities were evaluated. The decline in curve correction and implant-related complications were evaluated at follow-up. Clinical outcomes were evaluated using the Scoliosis Research Society-22 revised index. This study involved 50 patients with a mean age of 13.6 years and a mean follow-up duration of 5.52 years. With a mean coronal flexibility of 18.7%, the mean apical vertebral rotation (AVR), preoperative coronal Cobb angle, and sagittal kyphosis were 27.4°, 64.01°, and 47.70°, respectively. The postoperative mean coronal Cobb angle was 30.17° (p <0.05), and the sagittal kyphosis angle was 25.4° (p <0.05). The average AVR correction rate was 41.3%. The correction remained significant at the final mean follow-up, with a coronal Cobb angle of 34.14° and sagittal kyphosis of 25.02° (p <0.05). The average implant density was 1.41, with 46% of patients having a high implant density (HID). The HID had a markedly higher mean curve correction (29.30° vs. 38.05°, p <0.05) and a lower mean loss of correction (5.7° vs. 3.8°, p <0.05). Utilizing computer-assisted navigation, hybrid instrumentation, and multiple anchor point technique and attaining high implant densities, this study demonstrates successful outcomes following posterior-only surgical correction of dystrophic scoliosis in patients with NF-1.

A Cadaver-based Comparison of Sleeve-guided Implant-drill and Dynamic Navigation Osteotomy and Root-end Resections

IntroductionThis study compared the accuracy and efficiency of fully guided static and dynamic computer-assisted surgical navigation techniques for osteotomy and root-end resection (RER). MethodsFifty roots from cadaver heads were divided into two groups: fully guided static computer-assisted endodontic microsurgery (FG sCAEMS) and dynamic computer-assisted endodontic microsurgery (dCAEMS) (all, n = 25). Cone-beam computed tomography scans were taken pre and postoperatively. The osteotomy and RER were planned virtually in the preoperative cone-beam computed tomography scan and guided using 3D-printed surgical guides in the FG sCAEMS and 3D-dynamic navigation system in the dCAEMS. The 2D and 3D deviations and angular deflection were calculated. The osteotomy volume, resected root length, and resection angle were measured. The osteotomy and RER time and the number of procedural mishaps were recorded. ResultsFG sCAEMS was as accurate as dCAEMS, with no difference in the 2D and 3D deviation values or angular deflection (P > .05). The osteotomy and RER time were shortened using FG sCAEMS (P < .05). The FG sCAEMS showed a greater number of incomplete RERs than dCAEMS. Osteotomy volume, RER angle, and root length resected were similar in both groups (P > .05). FG sCAEMS and dCAEMS were feasible for osteotomy and RER. ConclusionsWithin the limitations of this cadaver-based study, FG sCAEMS was as accurate as dCAEMS. Both FG sCAEMS and dCAEMS were time-efficient for osteotomy and RER.

A computer-assisted navigation technique for complex primary knee arthroplasty with intra-articular bone defect and instability: A case report and literature review

Correction of a combined severe varus, bone defect, and ligamentous instability in a complex primary knee replacement is a technically demanding procedure. In such instances, constrained or rotating-hinge prosthesis is usually considered. Computer-assisted surgery in extra-articular deformity correction is a widely accepted and advantageous approach, but difficult to apply for intra-articular deformity due to difficulties with defining anatomical references. Our case report describes a patient with severe osteoarthritis, with intra-articular bone defects and ligament instability. We performed a computer-assisted navigation technique by combining gap balancing and measured resection techniques, with a metaphyseal sleeve as a new joint-line reference. We used an unconstrained posterior-stabilized (PS) prosthesis, incorporating Knee Society Scores (KSS): KSS-knee and KSS-function improved from 0–91 and 5–85, respectively, at one-month postoperatively. Our technique exhibited good short-term clinical outcomes and may decrease the requirement for constrained or rotating-hinge prostheses in a complex primary case.

Application of binocular visual navigation technique in diaphyseal fracture reduction.

Computer-assisted surgical navigation techniques have shown promise; however, currently popular systems have limitations. This paper presents the characterization and application of a binocular visual navigation technique in diaphyseal fracture reduction. A binocular visual tracker (MicronTracker) was introduced to reduce diaphyseal fractures. A transformation matrix was used to acquire the reduction parameters. A transverse diaphyseal fracture was used as a control group. Precision tests were performed with the binocular system using a simulation femoral model with a transverse fracture 12 times. All residual deformations were compared and P < 0.01. The binocular visual navigation technique produces good results with advantages of flexibility and high positional accuracy and shows promise. The MicronTracker might lead to further application in the remote navigation field.

ACCURACY OF PEDICLE SCREW INSERTION: A COMPARISON BETWEEN FLUOROSCOPIC GUIDANCE AND NAVIGATION TECHNIQUES.

ABSTRACTObjectives:To compare the accuracy of insertion of pedicle screws into the thoracic spine using fluoroscopic guidance or computer-assisted navigation techniques.Methods:Eight cadaveric thoracic spines were divided into two groups: the fluoroscopy group, in which pedicle screws were inserted with the guidance of a C-arm device, and the navigation group, in which insertion of the screws was monitored using computer-assisted navigation equipment. All procedures were performed by the same spinal surgeon. The rate of pedicle breach was compared between the two groups.Results:There was one intra-canal perforation in each group. Both perforations were medial in direction, and the breaches were 2 to 4 mm deep. There were no statistically significant differences in breach rate between the two groups.Conclusions:The accuracy of insertion of pedicle screws in the thoracic spine using computer-assisted navigation is equivalent to that achieved using fluoroscopic guidance. Computer-assisted navigation improves the safety of the surgical team during the procedure due to the absence of exposure to radiation. Therefore, there is a need for future randomized controlled trials to be conducted in the clinical setting to evaluate other outcomes, including duration of surgery and blood loss during the procedure. Level of evidence IV.

Accuracy of minimally invasive percutaneous thoracolumbar pedicle screws using 2D fluoroscopy: a retrospective review through 3D CT analysis.

In the literature, there is a large variation in the reported misplacement rates of pedicle screws. The use of minimally invasive surgical techniques is increasing and as such there has only been a small amount of data to look at the misplacement rate of percutaneously inserted thoracic and lumbar pedicle screws. A retrospective analysis of post-operative computed tomography (CT) scans were performed on 108 patients who underwent minimally invasive percutaneously inserted thoracic and lumbar pedicle screws by a single surgeon. Analysis of the screw trajectory using strict guidelines was performed using multiplanar reconstruction CT scan data to determine the accuracy of the pedicle screws. A total of 614 screws were inserted in vertebral levels T2 to S1. Twenty-five (4.07%) screws were considered misplaced having breached the pedicular cortex. Thoracic pedicle screws had a statistically higher misplacement rate than lumbar pedicle screws (14.67% vs. 2.60% respectively, P<0.001). A single screw required replacement (0.16%) and there were no permanent neurological deficits. The misplacement rates were lower than those reported for open screw placement and equivalent to 3D CT navigated misplacement rates. Percutaneously inserted pedicle screws using 2D fluoroscopy offers a safe and accurate option for spinal stabilisation with an extremely low misplacement rate and morbidity. Overall, the low misplacement rates were equivalent and in most cases lower compared to open and computer assisted navigation techniques. However, we would recommend that given a misplacement rate of 14.67% for thoracic pedicle screws that computer assisted navigation may be able to offer further improvements in accuracy.

A nonvel computer-assisted navigation for intraoperative correction of femoral rotation deformity in diaphyseal fractures

Objective To evaluate the clinical effect of a novel computer-assisted navigation technique for intraoperative correction of femoral rotation deformity in diaphyseal fractures. Methods From November 2015 to November 2016, a navigation system (BrainLAB, Germany) was used in antegrade in-tramedullary nailing for 13 patients with femoral shaft fracture to intraoperatively restore the normal length and rotation of the fractured femur. They were 11 men and 2 women, with an average age of 38.2 years. The injury affected the left side in 5 cases and the right side in 8. According to the Winquist Classification, there were 6 cases of typeⅠ, 3 ones of type Ⅱ, 3 ones of type Ⅲ, and one of type Ⅳ. This navigation system allowed the surgeons to detect and set the femoral anteversion (FAV) and length of the injured leg at the desired angle and length of the healthy contralateral femur, precisely matching the contralateral limb and restoring the normal length and rotation of the fractured femur. All the patients underwent postoperative CT scan of bilateral femora for measurement of the lengths and rotations which were compared with the intraoperative values obtained with the navigation system. Results Additional operative time required for computerized navigation averaged 42.8 min (from 35 to 55 min). The mean length difference between the treated and untreated femora was 4.2 mm (from 2 to 9 mm). The FAVs obtained from intraoperative navigation and postoperative CT scan were 34.0°±8.4° and 33.5°±8.3° in the healthy side and 31.2°±8.5° and 32.8°±9.0° in the injured side, showing no significant differences either between the 2 sides or between intraoperation and postoperation (P >0.05). The mean rotational difference between the 2 extremities were 4.8°±1.6° for the navigation and 3.8°±1.9° for the CT scan, showing an insignificant difference (P >0.05). All the incisions healed well with no intraoperative or postoperative complications. Conclusions This novel navigation technique may serve as a reliable tool to accurately correct the rotational malalignment of femoral shaft fractures intraoperatively, but care should be taken in every step of the navigation procedure to reduce complications. Key words: Femoral fractures; Fracture fixation, intramedullary internal; Surgery, computer-assisted; Bone nails

Spinal intraoperative three-dimensional navigation: correlation between clinical and absolute engineering accuracy

Background ContextSpinal intraoperative computer-assisted navigation (CAN) may guide pedicle screw placement. Computer-assisted navigation techniques have been reported to reduce pedicle screw breach rates across all spinal levels. However, definitions of screw breach vary widely across studies, if reported at all. The absolute quantitative error of spinal navigation systems is theoretically a more precise and generalizable metric of navigation accuracy. It has also been computed variably and reported in less than a quarter of clinical studies of CAN-guided pedicle screw accuracy. PurposeThis study aimed to characterize the correlation between clinical pedicle screw accuracy, based on postoperative imaging, and absolute quantitative navigation accuracy. Design/SettingThis is a retrospective review of a prospectively collected cohort. Patient SampleWe recruited 30 patients undergoing first-time posterior cervical-thoracic-lumbar-sacral instrumented fusion±decompression, guided by intraoperative three-dimensional CAN. Outcome MeasuresClinical or radiographic screw accuracy (Heary and 2 mm classifications) and absolute quantitative navigation accuracy (translational and angular error in axial and sagittal planes). MethodsWe reviewed a prospectively collected series of 209 pedicle screws placed with CAN guidance. Each screw was graded clinically by multiple independent raters using the Heary and 2 mm classifications. Clinical grades were dichotomized per convention. The absolute accuracy of each screw was quantified by the translational and angular error in each of the axial and sagittal planes. ResultsAcceptable screw accuracy was achieved for significantly fewer screws based on 2 mm grade versus Heary grade (92.6% vs. 95.1%, p=.036), particularly in the lumbar spine. Inter-rater agreement was good for the Heary classification and moderate for the 2 mm grade, significantly greater among radiologists than surgeon raters. Mean absolute translational-angular accuracies were 1.75 mm-3.13° and 1.20 mm-3.64° in the axial and sagittal planes, respectively. There was no correlation between clinical and absolute navigation accuracy. ConclusionsRadiographic classifications of pedicle screw accuracy vary in sensitivity across spinal levels, as well as in inter-rater reliability. Correlation between clinical screw grade and absolute navigation accuracy is poor, as surgeons appear to compensate for navigation registration error. Future studies of navigation accuracy should report absolute translational and angular errors. Clinical screw grades based on postoperative imaging may be more reliable if performed in multiple by radiologist raters.

Accuracy and postoperative assessment of pedicle screw placement during scoliosis surgery with computer-assisted navigation: a meta-analysis.

Accurate insertion of pedicle screws in scoliosis patients is a challenge for surgeons. Computer-assisted navigation techniques might help improve the accuracy of screw placement, thereby avoiding complications. Thus, the objective of this present work is to compare the accuracy and postoperative assessment of pedicle screw placement in scoliosis patients using a computer-assisted navigation technique and using a conventional free-hand method. A search of the PubMed, Cochrane, and Web of Science databases was executed. In vivo comparative studies that assessed the accuracy and postoperative evaluation of pedicle screw placement in scoliosis patients with or without navigation techniques were chosen and analyzed. The accuracy of pedicle screw insertion was significantly increased when using the navigation system, although the average operative time and correction rate was not significantly different from that with non-navigated surgery. The navigation technique improves the accuracy of pedicle screw placement during scoliosis surgery without prolonging the operative time or decreasing the deformity correction effect. Copyright © 2016 John Wiley & Sons, Ltd.

Real Time Navigation-Assisted Orbital Wall Reconstruction in Blowout Fractures.

Limitation in performing restoration of orbital structures is the narrow, deep, and dark surgical field, which makes it difficult to view the operative site directly. To avoid perioperative complications from this limitation, the authors have evaluated the usefulness of computer-assisted navigation techniques in surgical treatment of blowout fracture. Total 37 patients (14 medial orbital wall fractures and 23 inferior orbital wall fractures) with facial deformities had surgical treatment under the guide of navigation system between September 2012 and January 2015. All 37 patients were treated successfully and safely with navigation-assisted surgery without any complications, including diplopia, retrobulbar hematoma, globe injury, implant migration, and blindness. Blowout fracture can be treated safely under guidance of a surgical navigation system. In orbital surgery, navigation-assisted technology could give rise to improvements in the functional and aesthetic outcome and checking the position of the instruments on the surgical site in real time, without injuring important anatomic structures.

10-Year patient satisfaction compared between computer-assisted navigation and conventional techniques in minimally invasive surgery total knee arthroplasty

Background: Both minimally invasive surgery (MIS) and computer-assisted surgery (CAS) in total knee arthroplasty have been scientifically linked with surgical benefits. However, the long-term results of these techniques are still controversial. Most surgeons assessed the surgical outcomes with regard to knee alignment and range of motion, but these factors may not reflect subjective variables, namely patient satisfaction.Purpose: To compare satisfaction and functional outcomes between two technical procedures in MIS total knee arthroplasty, namely computer-assisted MIS and conventional MIS procedure, operated on a sample group of patients after 10 years.Methods: Seventy cases of posterior-stabilized total knee prostheses were implanted using a computer-assisted system and were compared to 74 cases of matched total knee prostheses of the same implant using conventional technique. Both groups underwent arthrotomy by 2 cm limited quadriceps exposure minimally invasive surgery (2 cm Quad MIS). At an average of 10 years after surgery, self-administered patient satisfaction and WOMAC scales were administered and analyzed.Results: Demographic data of both groups including sex, age, preoperative WOMAC and post-operative duration were not statistically different. Post-operative WOMAC for the computer-assisted group was 38.94 ± 5.68, while the conventional one stood at 37.89 ± 6.22. The median of self-administered patient satisfaction scales of the computer-assisted group was 100 (min37.5–max100), while the conventional one was 100 (min25–max100). p Value was 0.889. There was one re-operative case in the conventional MIS group due to peri-prosthetic infection which was treated with debridement, polyethylene exchanged and intravenous antibiotics.Conclusions: The 10-year outcomes of computer-assisted MIS total knee arthroplasty are not superior to that of the conventional MIS technique in function and patient satisfaction. 10 years may not be enough to show the difference between these two techniques.

A computer-assisted navigation technique to perform bone tumor resection without dedicated software

Purpose: In oncological orthopedics, navigation systems are limited to use in specialized centers, because specific, expensive, software is necessary. To resolve this problem, we present a technique using general spine navigation software to resect tumors located in different segments.Materials and Methods: This technique requires a primary surgery during which screws are inserted in the segment where the bone tumor is; next, a CT scan of the entire segment is used as a guide in a second surgery where a resection is performed under navigation control. We applied this technique in four selected cases. To evaluate the procedure, we considered resolution obtained, quality of the margin and its control.Results: In all cases, 1 mm resolution was obtained; navigation allowed perfect control of the osteotomies, reaching the minimum wide margin when desired. No complications were reported and all patients were free of disease at follow-up (average 25.5 months).Conclusions: This technique allows any bone segment to be recognized by the navigation system thanks to the introduction of screws as landmarks. The minimum number of screws required is four, but the higher the number of screws, the greater the accuracy and resolution. In our experience, five landmarks, placed distant from one another, is a good compromise. Possible disadvantages include the necessity to perform two surgeries and the need of a major surgical exposure; nevertheless, in our opinion, the advantages of better margin control justify the application of this technique in centers where an intraoperative CT scanner, synchronized with a navigation system or a dedicated software for bone tumor removal were not available.

An Ultra Low Noise Optoelectronic Module Enables an in Situ Range-Finder Probe to Locate a Neurovascular Bundle in Dental Implant Surgery

Dental implantology procedures necessitate surgical drilling of a hole in the jawbone to insert an artificial root over which a dental prosthesis is placed. The success factor of a dental implant is attaining successful osseointegration. This implies a deeper placed implant closest to the Inferior Alveolar Nerve (IAN) but not too close that it carries the risk of damaging this nerve-artery bundle located along the mandible line. Implications for perforating the IAN in patients can vary from temporary numbness to permanent loss of sensation in the lower facial area. Surgeons routinely use computer-assisted navigation techniques relying on static preoperative cone-beam X-ray computed tomography or other imaging methods such as Magnetic Resonance Imaging (MRI) to assess optimal anatomical distances in the patient’s jaw. However, variability of the measured IAN bundle position with these techniques is at the moment accurate to 30% at best. These techniques are known to introduce localization errors and do not benefit from in situ guidance. Therefore there is an important need for an online, in vivo probe to assess drill distances to a critical nerve-artery bundle in situ to not only avoid jaw paralysis but to improve overall outcome of the implantation.To this aim, we investigate a combined multimodal approach using Optical Coherence Tomography (OCT) for high resolution structural imaging, and functional NIR absorption detection in an optical fiber probe eventually small enough to fit into a surgical drill bit, for real-time evaluation of the distance from the probe to the IAN. We designed a reflectance fiber-optic probe to sense the pulsation of the artery (Heartbeat ~1-2Hz) in the IAN bundle, and a detection circuit board with a high gain (2 . 106 V/A), and very low noise (10mVRMS at output) and bandwidth (10Hz) shown on Figure 1.The success of this NIR channel for accurate real-time proximity sensing by capturing low frequency pulsing signals relies on an ultra low noise photon detection module. Measurements with this fiber probe were conducted at probe-target distances varying from 0mm (probe in contact) to 3mm. The results obtained are promising: the oscillating RMS amplitude varies as a function of distance in a similar fashion to previously published work in pulse oximetry literature [1]. The DC level also has a specific trend as a function of distance. Both AC and DC signal components can be used to extract useful distance information.Original designs using a lock-in amplifier to measure the very low RMS amplitude of the of the back-reflected light intensity, modulated by the spatially oscillating absorption changes due to flowing blood surrogate in an artery simulating tube were promising, but limited.Lock-in signal detection with a reference signal modulated at only 1-2 Hz needs filtering with long time constants. Moreover, clinical implementation with the heartbeat as the reference signal would make real-time measurement impractical. As such, we have developed a flexible optoelectronic detection platform with tunable bandwidth, gain and bias enabling the system to not be limited by electronics noise.Using custom phantoms of the jawbone and including a surrogate arterial dynamic pumping circuit, we demonstrated proof of concept for potential detection range of 0.5-4 mm at l-850nm with a source-detector separation of 1.8mm using the pulsating signal from an artery simulating tube. In compliment, a swept-source OCT at 1.3mm provided finer resolution sensitivity to the proximity of the IAN bundle in the 0-0.9mm range and offered the possibility of imaging the inhomogeneous IAN interface.Methods for calibrating and processing the data to provide robust long range NIR finding capabilities in combination with short-range high precision OCT imaging towards a complete clinical solution will be discussed.

Percutaneous pedicle screw placement with computer-navigated mapping in place of Kirschner wires

Percutaneous pedicle screw insertion techniques are commonly used to treat a variety of spinal disorders. Typically, Kirschner (K)-wires are used to guide the insertion of taps and screws during placement since the normal anatomical landmarks are not visualized. The use of K-wires adds risks, such as vascular and nerve injuries as well as increased radiation exposure given the use of fluoroscopy. The authors describe a series of patients who had percutaneous pedicle screws placed using a new computer-assisted navigation technique without the need for K-wires. Minimally invasive percutaneous pedicle screw placement in the thoracic and lumbar spine was performed in a consecutive series of 15 patients for a variety of spinal pathologies. Intraoperative 3D CT images were obtained and used with a computer-assisted navigation system to insert an awl-tap into each pedicle. The tap location in the pedicle was marked with the navigation software, and the awl-tap was then removed. The navigation system was used to identify each landmark to insert the pedicle screw. Connecting rods were then inserted percutaneously under fluoroscopic guidance. Postoperative CT scans were obtained in each patient to evaluate screw placement. On postprocedure scanning, only 1 screw had a minor lateral and superior breach that was asymptomatic. To date, there have been no hardware failures. Percutaneous pedicle screws can be placed effectively and safely without the use of K-wires.

Comparison of Surface Area across the Allograft-Host Junction Site Using Conventional and Navigated Osteotomy Technique

Bulk allograft reconstruction plays an important role in limb-salvage surgery; however, non-union has been reported in up to 27% of cases. The purpose of this study is to quantify average surface contact areas across simulated intraoperative osteotomies using both free-hand and computer-assisted navigation techniques. Pressure-sensitive paper was positioned between two cut ends of a validated composite sawbone and compression was applied using an eight-hole large fragment dynamic compression plate. Thirty-two samples were analyzed for surface area contact to determine osteotomy congruity. Mean contact area using the free-hand osteotomy technique was equal to 0.21 square inches. Compared with a control of 0.69 square inches, average contact area was found to be 30.5% of optimal surface contact. Mean contact area using computer-assisted navigation was equal to 0.33 square inches. Compared with a control of 0.76 square inches, average contact area was found to be 43.7% of optimal surface contact. Limited contact achieved using standard techniques may play a role in the high rate of observed non-union, and an increase in contact area using computer-assisted navigation may improve rates of bone healing. The development of an oncology software package and navigation hardware may serve an important role in decreasing non-union rates in limb salvage surgery.

Pedicle screw placement in the thoracic spine: a randomized comparison study of computer-assisted navigation and conventional techniques

Objective To evaluate the accuracy of computer-assisted pedicle screw installation and its clinical benefit as compared with conventional pedicle screw installation techniques. Methods Total 176 thoracic pedicle screws placed in 42 thoracic fracture patients were involved in the study randomly, 20 patients under conventional fluoroscopic control (84 screws) and 22 patients had screw insertion under three dimensional (3D) computer-assisted navigation (92 screws). The 2 groups were compared for accuracy of screw placement, time for screw insertion by postoperative thin-cut CT scans and statistical analysis by χ 2 test. The cortical perforations were then graded by 2-mm increments: Grade I (good, no cortical perforation), Grade II (screw outside the pedicle <2 mm), Grade III (screw outside the pedicle >2 mm). Results In computer assisted group, 88 (95.65%) were Grade I (good), 4 (4.35%) were Grade II (<2mm), no Grade III (>2 mm) violations. In conventional group, there were 14 cortical violations (16.67%), 70 (83.33%) were Grade I (good), 11 (13.1%) were Grade II (<2 mm), and 3 (3.57%) were Grade III (>2 mm) violations ( P<0.001). The number (19.57%) of upper thoracic pedicle screws (T 1-T 4) inserted under 3D computer-assisted navigation was significantly higher than that (3.57%) by conventional fluoroscopic control ( P <0.001). Average screw insertion time in conventional group was (4.56 ±1.03) min and (2.54 ± 0.63) min in computer assisted group ( P<0.001). In the conventional group, one patient had pleura injury and one had a minor dura violation. Conclusions This study provides further evidence that 3D computer-assisted navigation placement of pedicle screws can increase accuracy, reduce surgical time, and be performed safely and effectively at all levels of the thoracic spine, particularly upper thoracic spine.

Pedicle Screw Placement in the Thoracic Spine: A Comparison Study of Computer-Assisted Navigation and Conventional Techniques

The technique of computer-assisted pedicle screw installation and its clinical benefit as compared with conventional pedicle screw installation was evaluated. Twenty-two patients had thoracic screw insertion under 3-dimentional computer-assisted navigation (92 screws) and 20 patients under conventional fluoroscopic control (84 screws). The 2 groups were compared for accuracy of screw placement, screw insertion time by postoperative thin-cut computed tomography scans, and statistical analysis. The cortical perforations were graded by 2-mm increments. In the computer group, 88 (95.65%) were grade I (good), 4 (4.35%) were grade II (<2 mm), and 0 were grade III (>2 mm) violations. There were 4 cortical violations (3.57%). In the conventional group, there were 14 cortical violations (16.67%), 70 (83.33%) were grade I (good), 11 (13.1%) were grade II (<2 mm), and 3 (3.57%) were grade III (>2 mm) violations (P<.001). The number (19.57%) of upper thoracic pedicle screws (T1-T4) inserted under 3-dimensional computer-assisted navigation was significantly higher than that (3.57%) by conventional fluoroscopic control (P<.001). Average screw insertion time in the conventional group was more than in the computer group (P<.001). Three-dimensional computer-assisted navigation pedicle screw placement can increase accuracy, reduce surgical time, and be performed safely and effectively at all levels of the thoracic spine, particularly the upper thoracic spine.

Reliability of computer-assisted surgery as an intraoperative ruler in navigated high tibial osteotomy

BackgroundComputer-assisted surgery (CAS) can act as an intraoperative ruler in high tibial osteotomy (HTO) to visualize continuously the leg during surgery.QuestionsThe aim of the study is to evaluate the accuracy of CAS with respect to preoperative planning and postoperative deviation from the planned leg axis in HTO. In addition, the influence of surgeon experience as well as operation time and perioperative complications are analyzed.MethodsA prospective multicenter study case series with follow-up at 6 weeks was performed in six centers. Medial open-wedge HTO with Tomofix® was done using computer assisted navigation technique with the Brainlab VV Osteotomy 1.0 module.ResultsFifty-one patients with medial gonarthritis were treated with navigated HTO. The follow-up rate was 98%. The majority of HTO–CAS patients fell within the tolerated limit of ±3° for leg axis deviation, however, seven patients were reported with deviations outside of this range: three patients had deviations of >3°–4.5° and four patients >4.5°, respectively. Eight intraoperative complications were documented, partially resulting from technical problems associated with the navigation system. During the 6-week follow-up period, three postoperative complications were experienced, all not associated with navigation technology.ConclusionsIn about 85% of cases, a perfect result in terms of deviation of the planned mechanical leg axis could be achieved. Computer assistance in HTO proved to be a helpful tool regarding intraoperative control of leg axis.Level of evidenceLevel I, High quality prospective study (all patients were enrolled at the same preoperative planning point with ≥80% follow-up of enrolled patients).

Fat Emboli in Total Knee Arthroplasty: A Prospective Randomized Study of Computer-Assisted Navigation vs Standard Surgical Technique

A prospective exploratory study of fat emboli in patients undergoing total knee arthroplasty was performed in patients randomly assigned to surgery with computer-assisted navigation or standard technique. Transesophageal echocardiography of the right atrium was recorded for 5 consecutive 1-minute intervals after tourniquet deflation. Emboli were graded on a scale of 0 to 3 based on embolism size, amount of atrium filled, and duration of embolic shower, creating an overall score of 0 to 9. The mean (SD, range) of the 5 overall scores for each total knee arthroplasty was 6.00 (0.76, 4.6-7.4) for computer-assisted navigation (22 patients) and 6.42 (0.97, 4.6-7.9) for standard technique (22 patients) ( P = .14), with a 95% confidence interval for the difference of −0.11 to 0.95. We conclude that any difference in extent of emboli between the 2 surgical techniques is unlikely to be of clinical significance.

Clinical applications of computer-assisted navigation technique in spinal pedicle screw internal fixation

To assess the value of computer navigation technique in spinal pedicle screw insertion. 95 patients undergoing spinal pedicle screw internal fixation were randomly divided in 2 groups:navigation group (n=36) undergoing pedicle screw insertion with computer-assisted navigation technique, and conventional group (n=50) undergoing pedicle screw insertion using conventional anatomic landmark combined. The 2 groups were compared in respect to screw canal preparation time, accuracy of screw position, and incidence of postoperative complication. 206 screws were inserted in the navigation group, 169 being with excellent outcome (82.0%), 29 with good outcome (14.1%), and 8 with bad outcome (3.9%). Nine patients in the navigation group failed to adopt the computer-assisted navigation technique because of different reasons. 285 screws were inserted in the conventional group, 257 being were excellent outcome (90.2%), 28 with good outcome (9.8%), and none with bad outcome. The general fitness rate of the navigation group was 96.1%, not significantly different from that of the conventional group (100%, P>0.05). The screw canal preparation time of the navigation group was (360+/-22) sec, significantly longer than that of the conventional group [(56+/-8) sec, P<0.001)]. No postoperative complication was found in both groups. The accuracy of pedicle screw insertion using preoperative CT-based navigation technique is not different from that using conventional anatomic landmark, but the operation time is significantly prolonged. Preoperative CT-based navigation technique has limited value in spinal pedicle screw insertion.