Assessment Of Pedicle Screw Placement Research Articles

Intraoperative Cone-Beam Computed Tomography Assessment of Spinal Pedicle Screws Placement Precision Is in Full Agreement with Postoperative Computed Tomography Assessment

To assess agreement between pedicle screw placement evaluated on post-operative computed tomography (CT) and on intra-operative cone beam computed tomography (CBCT) and compare procedure characteristics when using 1st and 2nd generation robotic C-arm systems in the hybrid operation room. All patients who received pedicle screws for spinal fusion at our institution between June 2009 and September 2019 and underwent intra-operative CBCT and post-operative CT were included. The CBCT and CT images were reviewed by two surgeons to assess the screw placement using the Gertzbein-Robbins and the Heary classifications. Inter-method agreement of screw placement classifications -as well as inter-rater agreement were assessed using Brennan-Prediger and Gwet's agreement coefficients. Procedure characteristics using 1st and a 2nd generation robotic C-arm systems were compared. Fifty-seven patients were treated with 315 pedicle screws at thoracic, lumbar and sacral levels. No screw had to be repositioned. On CBCT, accurate placement was found for 309 (98.1%) screws using the Gertzbein-Robbins classification and 289 (91.7%) using the Heary classification and on CT these were 307 (97.4%) and 293 (93.0%) respectively. Inter-method between CBCT and CT, and inter-rater agreements between the two raters were almost perfect (>0.90) for all assessment. There were no significant differences in mean radiation dose (p=0.83) and fluoroscopy time (p=0.82), but length of surgery using the 2nd generation system was estimated 107.7 min (95% CI: 31.9 to 183.5min, p=0.006) shorter. Intra-operative CBCT provides accurate assessment of pedicle screw placement and enables intra- operative repositioning of misplaced screws.

Postoperative 320 multi-slice computed tomography in assessment of pedicle screw insertion in thoraco-lumbar fixation

BackgroundPedicle screw instrumentation is used widely in lumbar spine for stabilization to enhance arthrodesis and has been accepted in the thoracic spine in recent years. The purpose of this study was to assess the value of postoperative 320 multi-slice computed tomography (MSCT) in assessment of pedicle screw placement in patients with spinal fixation with clinical and surgical correlation.ResultsA total of 340 pedicular screws were inserted to 70 cases. 286 (84.12%) were in, 54 screws (15.88%) were violated, and revision surgeries were required for 5 displaced screws. On axial, coronal reconstruction and three-dimensional (3D) reformatted CT images 36, 47, and 54 displaced screws were detected, respectively. Both sensitivity and specificity for 3D reformatted images were 100%. For axial image, they were 97.6% and 89.4%, respectively, compared with surgical findings in 5 revised screws.ConclusionMulti-slice CT scan is a valuable and valid postoperative assessment tool of accuracy of spinal pedicle screw placement.

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.

Reliability of Postoperative Multislice Computed Tomography in Assessment of Pedicle Screw Placement in Thoracic and Lumbar Spinal Fixation

Objective This study aims to evaluate the reliability of three-dimensional (3D) volume rendering computed tomography (CT) in postoperative assessment of pedicle screw placement. Methods A total of 98 patients with previous spinal fixation surgery were included. All inserted screws were evaluated postoperatively within the first week using CT. Degree of misplacement and difference between CT images were recorded. Results Overall, 76, 68, and 39 misplaced screws were detected in 3D reformatted image, coronal reconstruction, and axial CT images, respectively. Dorsal spine had higher rate of violation 46 (9.95%) with the highest rate at T4 (12.8%) comparing it with lumber 32 (6.9%). Statistically significant differences were found between lateral and medial violation ( p = 0.03), between findings of CT 3D reformatted and axial image ( p = 0.04), and also in detecting end plate perforation and anterior vertebral encroachment in different CT images ( p = 0.013). Sensitivity for 3D reformatted image and axial image compared with surgical finding in six revised screws was 100 and 95.8% and specificity 100 and 88.7%, respectively. Highly momentous agreement reported with Kappa coefficient = 0.95 Â ± < 0.001. Conclusion The vertebral body and the pedicle are 3D structures. Therefore, we have to study them as they are. The postoperative evaluation of pedicle screw using CT 3D reconstruction was a reliable method and unveiled the deficiencies in conventional axial CT.

The medial cortical pedicle screw—a new technique for cervical pedicle screw placement with partial drilling of medial cortex

Background contextStudies on cadavers have shown that the appropriate insertion of cervical pedicle screw (C3–C7) should be done from a more lateral point and at a steeper angle in the axial plane, than that described by Abumi et al., to decrease the chances of lateral perforation. PurposeWe describe a new technique for cervical pedicle screw (CPS) placement (C3–C7) using high-speed pneumatic drill with partial drilling of medial cortex for decreasing the chances of lateral perforation. Study designDescription of new surgical technique with retrospective data analysis. Patient sampleTwenty-five patients undergoing cervical spine surgery with CPS instrumentation in the lower cervical spine (C3–C7) from April 2011 to October 2012 at our institute were included in the study. Outcome measuresAll patients were evaluated with computed tomography scans postoperatively for the assessment of pedicle screw placement. Pedicle screw perforations were graded with the following criteria: Grade I perforations having ≤50% of the screw outside the pedicle and Grade II perforations having >50% of the screw outside the pedicle. Clinical complications directly related to CPS placement were also recorded. MethodsTwenty-five patients undergoing surgery with CPS instrumentation (C3–C7) at our institute between April 2011 and October 2012 were included in the study. Thirteen patients had cervical trauma, 10 had cervical spondylotic myelopathy, 1 had congenital cervico-dorsal scoliosis, and 1 was a patient with ankylosing spondylitis. Pedicle screw insertion was made according to the technique by Abumi et al., with the use of blunt pedicle probes in eight of these cases (Group I). In the other 17 cases (Group II), the pilot hole was made with the use of 2-mm diamond tipped burr, partially drilling the medial cortex and entering the vertebral body with the burr itself. ResultsA total of 131 CPSs (C3–C7) were inserted in 25 patients. In Group I, 43 pedicle screws were placed and 88 screws were placed in Group II, with partial drilling of medial cortex. Lateral perforations: in Group-I, more of lateral perforations were observed with 18.6% Grade I and 9.3% Grade II lateral perforations. In Group II, the lateral perforations were lower with 7.95% Grade I and 1.1% of Grade II lateral perforations. I Group-I, medial perforations were lower with 11.62% Grade I and 2.3% Grade II perforations. In Group II, the Grade I and Grade II medial perforations were 30.7% and 4.5%, respectively. The lateral perforations were more at C3, C4 levels, and the medial perforation was maximum at C5 level. No clinical neurovascular complications, directly related to screw placements, were seen in either of the groups postoperatively. ConclusionsWith the use of the technique by Abumi et al., more than half of the cervical pedicle screw perforations described are lateral. Use of a blunt pedicle probe usually directs the surgeon toward the lateral cortex as the medial cortex is thicker and stronger. With the new medial cortical pedicle screw technique described, lateral perforations were low. However, surgeons attempting this technique should be aware of the increase in medial perforations experienced by the authors with the new technique. The study gives an additional option of technique to be considered by surgeons already using CPS placements in selected patients. Further evaluation for reproducibility of the medial cortical pedicle screw technique by other surgeons and testing of biomechanical strength of the screws is required.

Role of postoperative multislice computed tomography in assessment of pedicle screw placement in spinal surgical fixation

ObjectiveTo evaluate the role of three-dimensional (3D) volume rendering computed tomography (CT), in the postoperative assessment of pedicle screw placement. MethodsNinety-eight patients with previous spinal fixation surgery were included. All inserted screws were evaluated post operatively within the first month using CT. Degree of misplacement and difference between CT images were recorded. ResultsSeventy six, 68 and 39 misplaced screws were detected in 3D reformatted image, coronal reconstruction and axial CT images, respectively. Dorsal spine had the higher rate of violation of 46 (9.95%) with the highest rate at T4 (12.8%) compared with lumbar of 32 (6.9%). Statistically significant differences were found between lateral and medial violation (P value −0.03), between findings of 3D CT reformatted and axial images (P=0.04), and also in detecting end plate perforation and anterior vertebral encroachment in different CT images (P value −0.013). Sensitivity for 3D reformatted image and axial image compared with surgical finding in six revised screws was 100% and 95.8% and specificity was 100% and 88.7%, respectively. Highly momentous agreement is reported with Kappa coefficient=0.95±<0.001. ConclusionWe conclude that postoperative evaluation of pedicle screw using 3D CT reconstruction was a reliable method.

Computer tomography assessment of pedicle screw placement in thoracic spine: comparison between free hand and a generic 3D-based navigation techniques

Although pedicle screw fixation is a well-established technique for the lumbar spine, screw placement in the thoracic spine is more challenging because of the smaller pedicle size and more complex 3D anatomy. The intraoperative use of image guidance devices may allow surgeons a safer, more accurate method for placing thoracic pedicle screws while limiting radiation exposure. This generic 3D imaging technique is a new generation intraoperative CT imaging system designed without compromise to address the needs of a modern OR. The aim of our study was to check the accuracy of this generic 3D navigated pedicle screw implants in comparison to free hand technique described by Roy-Camille at the thoracic spine using CT scans. The material of this study was divided into two groups: free hand group (group I) (18 patients; 108 screws) and 3D group (27 patients; 100 screws). The patients were operated upon from January 2009 to March 2010. Screw implantation was performed during internal fixation for fractures, tumors, and spondylodiscitis of the thoracic spine as well as for degenerative lumbar scoliosis. The accuracy rate in our work was 89.8 % in the free hand group compared to 98 % in the generic 3D navigated group. In conclusion, 3D navigation-assisted pedicle screw placement is superior to free hand technique in the thoracic spine.

Accuracy and Safety Assessment of Pedicle Screw Placement Using the Rapid Prototyping Technique in Severe Congenital Scoliosis

The application of rapid prototyping (RP) technique for improving accuracy of pedicle screw placement in congenital scoliosis is described in this study. To compare the accuracy and safety of pedicle screw placement in congenital scoliosis using the RP technique versus the conventional fluoroscopy. Maldeveloped vertebral components in congenital scoliosis leads to prolonged operation time and higher rate of screw misplacement. RP technique can enhance preoperative and perioperative planning. No data are available on the accuracy of pedicle screw fixation using the RP technique. Sixty-two consecutive patients with hemivertebra had undergone posterior-only hemivertebra resection. Pedicle screws were implanted either by the conventional intraoperative fluoroscopy technique (C-arm group; n=28) or the RP technique (RP group; n=34). Accuracy of pedicle screw placement was compared by postoperative computed tomographic scan. Seventy of 677 inserted screws were found to be misplaced, showing an overall accuracy of 89.7% (90.8% in the thoracic spine and 87.4% in the lumbar spine). In the C-arm group, 86.1% (167 of 194) and 82.0% (82 of 100) of screws were accurately placed in the thoracic and lumbar spine, respectively. While in the RP group, the respective screw placement accuracies were 94.4% (238 of 252) and 91.6% (120 of 131). In the C-arm and the RP groups, 94.8% (279 of 294) and 97.9% (375 of 383) of the screws were within the safety zone, respectively. Compared with the fluoroscopy method, the RP-assisted technique showed a shorter operation time and higher scoliosis correction rate. No neurovascular-related complication was observed with this technique during the study. The application of RP technique in congenital scoliosis can reduce the operation time, the risk of screw misplacement and its consequent complications. The use of RP technique in congenital scoliosis is safe and efficacious.

Computer tomography assessment of pedicle screw placement in lumbar and sacral spine: comparison between free-hand and O-arm based navigation techniques

Transpedicular screw fixation has been accepted worldwide since Harrington et al. first placed pedicle screws through the isthmus. In vivo and in vitro studies indicated that pedicle screw insertion accuracy could be significantly improved with image-assisted systems compared with conventional approaches. The O-arm is a new generation intraoperative imaging system designed without compromise to address the needs of a modern OR like no other system currently available. The aim of our study was to check the accuracy of O-arm based and S7-navigated pedicle screw implants in comparison to free-hand technique described by Roy-Camille at the lumbar and sacral spine using CT scans. The material of this study was divided into two groups, free-hand group (group I) (30 patients; 152 screws) and O-arm group (37 patients; 187 screws). The patients were operated upon from January to September 2009. Screw implantation was performed during PLIF or TLIF mainly for spondylolisthesis, osteochondritis and post-laminectomy syndrome. The accuracy rate in our work was 94.1% in the free-hand group compared to 99% in the O-arm navigated group. Thus it was concluded that free-hand technique will only be safe and accurate when it is in the hands of an experienced surgeon and the accuracy of screw placement with O-arm can reach 100%.

Assessment of Pedicle Screw Placement Using Intraoperative Computed Tomography (CT) in Complex Adult Deformity Patients

Assessment of Pedicle Screw Placement Using Intraoperative Computed Tomography (CT) in Complex Adult Deformity Patients

Pedicle Screw Placement Accuracy

A meta-analysis of the published literature was conducted specifically looking at accuracy and the postoperative methods used for the assessment of pedicle screw placement in the human spine. This study specifically aimed to identify postoperative methods used for pedicle screw placement assessment, including the most common method, and to report cumulative pedicle screw placement study statistics from synthesis of the published literature. Safety concerns have driven specific interests in the accuracy and precision of pedicle screw placement. A large variation in reported accuracy may exist partly due to the lack of a standardized evaluation method and/or the lack of consensus to what, or in which range, is pedicle screw placement accuracy considered satisfactory. A MEDLINE search was executed covering the span from 1966 until 2006, and references from identified papers were reviewed. An extensive database was constructed for synthesis of the identified studies. Subgroups and descriptive statistics were determined based on the type of population, in vivo or cadaveric, and separated based on whether the assistance of navigation was employed. In total, we report on 130 studies resulting in 37,337 total pedicle screws implanted, of which 34,107 (91.3%) were identified as accurately placed for the combined in vivo and cadaveric populations. The most common assessment method identified pedicle screw violations simply as either present or absent. Overall, the median placement accuracy for the in vivo assisted navigation subgroup (95.2%) was higher than that of the subgroup without the use of navigation (90.3%). Navigation does indeed provide a higher accuracy in the placement of pedicle screws for most of the subgroups presented. However, an exception is found at the thoracic levels for both the in vivo and cadaveric populations, where no advantage in the use of navigation was found.

Stepwise Methodology for Plain Radiographic Assessment of Pedicle Screw Placement: A Comparison With Computed Tomography

The objective of this study is to evaluate the effectiveness of a specific methodology for plain radiographic assessment of lumbar pedicle screw position. To evaluate the effectiveness of using orthogonal plain radiographs and a systematic method of interpretation, developed by the senior author, in assessing the placement of lumbar and lumbosacral pedicle screws. This was an adult cadaver study of the accuracy of using plain radiographs or computed tomography to assess pedicle screw position. Plain radiographs were performed and compared with computed tomography (CT) scans. Gross anatomic dissections were performed to directly confirm screw position. Variables, including screw material, radiographic view, and screw dimensions, were assessed for their effect on the ability of physicians to determine pedicle screw position. Multiple readers were included in the study, including 1 spine Fellow, 3 experienced orthopedic spine surgeons, and 1 neuroradiologist. Five adult cadaveric spines were instrumented with titanium pedicle screws from L1 to S1. Screws were placed outside the confines of the pedicle in all 4 quadrants or within the pedicle using a Latin-Square design. Each cadaver was imaged with orthogonal radiographs and high-resolution CT scans. The spines were then reimaged after the instrumentation was replaced with stainless steel screws placed in the identical position. Finally, each spine was dissected to assess the exact position of the screws. Images were read in a blinded fashion by 1 spine fellow, 2 staff surgeons, and a staff radiologist. The results were compared with the known screw positions at dissection. In total, 120 pedicle screws were placed, 44 (38%) outside the confines of the pedicle. Sensitivity, defined as the percent of the misplaced screws that were correctly identified, was similar across the 3 diagnostic tests, but markedly improved when all CT formats were considered together. Similarly, specificity, defined as the percent of screws correctly read as being placed within the pedicle, was independent of radiographic examination. Sensitivity of the radiographic technique was 70.1% and specificity was 83.0%, whereas sensitivity for CT scans was 84.7% and specificity was 89.7%. There was an observed association with anatomic level, with a consistently less accuracy in detecting screw position at L1 with plain x-ray (P=0.001). Additionally, correct position of stainless steel screws was more difficult to detect as compared with titanium (P=0.033) using either x-rays or CT. Other variables examined, such as screw length and screw diameter, did not have an effect on the ability to read the positioning. CT scans, often considered the "gold standard" for clinical assessment of pedicle screw placement, have limitations when validated with gross anatomical dissection. The described systematic method for evaluating pedicle screw placement using orthogonal plain radiographs attained accuracy comparable to high-resolution CT scans.

Observer reliability in evaluating pedicle screw placement using computed tomography

Pedicle screw insertion in spinal surgery is a demanding technique with potential risks to neurological structures, for example, within the spinal canal. Assessing screw placement in clinical practice has been performed using plain radiographs and/or mainly axial computed tomography (CT) images. Screw placement using CT image reconstructions in multiple planes has been described, but its reliability has yet to be studied. This study aimed at addressing the clinical issue of interobserver and intraobserver reliability in the use of axial and coronal CT images for the assessment of pedicle screw placement. Fifty nine pedicle screws were studied by two experienced radiologists on two separate occasions. Screw placement was classified as "in", "out" or "questionable". On average, 88% and 92% of the screws were classified as "in" by the first and second radiologist, respectively. Intraobserver agreement strength was almost perfect for both observers using either axial or coronal images. Interobserver agreement strength was almost perfect (axial) and substantial (coronal) in the first reading and substantial (axial, coronal) in the second reading. Assessing screw placement in more than one CT imaging plane is not only useful but reliable. Routine use may enhance reporting quality of screw placement by surgeons and radiologists.

Accuracy of single-time, multilevel registration in image-guided spinal surgery

Background context Computerized frameless stereotactic image-guidance has been used in recent years to improve the accuracy and safety of pedicle screw placement during spine surgery. Because the possibility of intervertebral motion exists, and because the patient is usually in a different position when preoperative imaging is performed compared with the operative position, it has been suggested that the imaging model of the complete lumbar spine and the surgically exposed lumbar spine may be significantly discordant. Consequently, current protocols suggest registering each spinal level (single-level registration) separately before pedicle screw placement at that level, a time-consuming process. Purpose To assess the accuracy of single-time multilevel registration for multilevel pedicle screw placement during image-guided, computer-assisted spine surgery, in the setting of degenerative disorders of the lumbar spine. Study design/setting This is a prospective clinical and radiological study of 45 patients with degenerative disorders of the lumbar spine who underwent instrumented fusion with the use of single-time multilevel registration computer-assisted, image-guided tomography. The accuracy of the pedicle screws placement was confirmed on the basis of a protocol that included intraoperative spontaneous electromyographic (EMG) recordings, direct pedicle visualization, and computer tomography (CT) scans when clinically indicated during the follow-up period. Patient sample Forty-five consecutive patients who fulfilled the criteria of computer-assisted, image-guided tomography pedicle screw placement for degenerative lumbar spine disease without overt instability. Outcome measures The principal outcome measure was the accuracy of pedicle screw placement with single-time multilevel registration for multilevel pedicle screw placement during image-guided, computer-assisted spine surgery; postoperative CT performed for clinical indications during the follow-up course was used for the assessment of pedicle screw placement. Methods Patients were assessed clinically before and after the operation. Data from 45 consecutive cases of image-guided, computer-assisted lumbar spinal fusion were statistically analyzed to determine the relationship between the number of levels registered during single-time registry and the mean registration error (MRE). Intraoperative spontaneous EMG, direct visualization, and postoperative CT scans were used to assess the accuracy of pedicle screw insertion. Results None of the patients involved in this study experienced clinical sequelae of improper pedicle screw placement. MREs after surface mapping and after point merge were small (less than 1.00 mm and less than 3.00 mm, respectively). During the intraoperative assessment of the pedicle screws placement, no significant spontaneous EMG activity was recorded and the pedicular walls were found intact in direct visualization. The postoperative CT scans showed in 10 patients accurate placement in 55 of the 57 pedicle screws with expansion of the medial wall in two screws. Conclusions Single-time, multilevel registration may decrease operative time relative to repeated, single-level registrations, without compromising the increased accuracy of pedicle screw placement afforded by this technique in the setting of degenerative disorders of the lumbar spine. Despite the advantages in computer-guided image surgery, cautious application in the individual patient is recommended until more comprehensive data can be gathered in specific degenerative pathology with overt instability; thus the knowledge of the anatomy remains crucial.