Ability of electromyographic monitoring to determine the presence of malpositioned pedicle screws in the lumbosacral spine: analysis of 2450 consecutively placed screws

2011 ◽  
Vol 15 (2) ◽  
pp. 130-135 ◽  
Author(s):  
Scott L. Parker ◽  
Anubhav G. Amin ◽  
S. Harrison Farber ◽  
Matthew J. McGirt ◽  
Daniel M. Sciubba ◽  
...  

Object Pedicle screws provide efficient stabilization along all 3 columns of the spine, but they can be technically demanding to place, with malposition rates ranging from 5% to 10%. Intraoperative electromyographic (EMG) monitoring has the capacity to objectively identify a screw breaching the medial pedicle cortex that is in proximity to a nerve root. The purpose of this study is to describe and evaluate the authors' 7-year institutional experience with intraoperative EMG monitoring during placement of lumbar pedicle screws and to determine the clinical utility of intraoperative EMG monitoring. Methods The authors retrospectively studied 2450 consecutive lumbar pedicle screws placed in 418 patients from June 2002 through June 2009. All screws were inserted using a free-hand technique and anatomical landmarks, stimulated at 10.0 mA, and evaluated with CT scanning within 48 hours postoperatively. Medial pedicle screw breach was defined as having greater than 25% of the screw diameter extend outside of the pedicle, as confirmed on CT scanning or intraoperatively by a positive EMG response indicating a medial breach. The sensitivity and specificity of intraoperative EMG monitoring in detecting the presence of a medial screw breach was evaluated based on the following definitions: 1) true positive (a positive response to EMG stimulation confirmed as a breach intraoperatively or on postoperative CT scans); 2) false positive (positive response to EMG stimulation confirmed as a correctly positioned screw on postoperative CT scans); 3) true negative (no response to EMG stimulation confirmed as a correctly positioned screw on postoperative CT scans); or 4) false negative (no response to EMG stimulation but confirmed as a breach on postoperative CT scans). Results One hundred fifteen pedicle screws (4.7%) showed positive stimulation during intraoperative EMG monitoring. At stimulation thresholds less than 5.0, 5.0–8.0, and > 8.0 mA, the specificity of a positive response was 99.9%, 97.9%, and 95.9%, respectively. The sensitivity of a positive response at these thresholds was only 43.4%, 69.6%, and 69.6%, respectively. At a threshold less than 5.0 mA, 91% of screws with a positive EMG response were confirmed as true medial breaches. However, at thresholds of 5.0–8.0 mA or greater than 8.0 mA, a positive EMG response was associated with 89% and 100% false positives (no breaches), respectively. Conclusions When using intraoperative EMG monitoring, a positive response at screw stimulation thresholds less than 5.0 mA was highly specific for a medial pedicle screw breach but was poorly sensitive. A positive response to stimulation thresholds greater 5.0 mA was associated with a very high rate of false positives. The authors' experience suggests that pedicle screws showing positive stimulation below 5.0 mA warrants intraoperative investigation for malpositioning while responses at higher thresholds are less reliable at accurately representing a medial breach.

2020 ◽  
Vol 32 (4) ◽  
pp. 542-547 ◽  
Author(s):  
Huan Liu ◽  
Junlong Wu ◽  
Yu Tang ◽  
Haiyin Li ◽  
Wenkai Wang ◽  
...  

OBJECTIVEThe authors aimed to assess, in a bone-agar experimental setting, the feasibility and accuracy of percutaneous lumbar pedicle screw placements using an intraoperative CT image–based augmented reality (AR)–guided method compared to placements using a radiograph-guided method. They also compared two AR hologram alignment methods.METHODSTwelve lumbar spine sawbones were completely embedded in hardened opaque agar, and a cubic marker was fixed on each phantom. After intraoperative CT, a 3D model of each phantom was generated, and a specialized application was deployed into an AR headset (Microsoft HoloLens). One hundred twenty pedicle screws, simulated by Kirschner wires (K-wires), were placed by two experienced surgeons, who each placed a total of 60 screws: 20 placed with a radiograph-guided technique, 20 with an AR technique in which the hologram was manually aligned, and 20 with an AR technique in which the hologram was automatically aligned. For each K-wire, the insertion path was expanded to a 6.5-mm diameter to simulate a lumbar pedicle screw. CT imaging of each phantom was performed after all K-wire placements, and the operative time required for each K-wire placement was recorded. An independent radiologist rated all images of K-wire placements. Outcomes were classified as grade I (no pedicle perforation), grade II (screw perforation of the cortex by up to 2 mm), or grade III (screw perforation of the cortex by > 2 mm). In a clinical situation, placements scored as grade I or II would be acceptable and safe for patients.RESULTSAmong all screw placements, 75 (94%) of 80 AR-guided placements and 40 (100%) of 40 radiograph-guided placements were acceptable (i.e., grade I or II; p = 0.106). Radiograph-guided placements had more grade I outcomes than the AR-guided method (p < 0.0001). The accuracy of the two AR alignment methods (p = 0.526) was not statistically significantly different, and neither was it different between the AR and radiograph groups (p < 0.0001). AR-guided placements required less time than the radiograph-guided placements (mean ± standard deviation, 131.76 ± 24.57 vs 181.43 ± 15.82 seconds, p < 0.0001). Placements performed using the automatic-alignment method required less time than those using the manual-alignment method (124.20 ± 23.80 vs 139.33 ± 23.21 seconds, p = 0.0081).CONCLUSIONSIn bone-agar experimental settings, AR-guided percutaneous lumbar pedicle screw placements were acceptable and more efficient than radiograph-guided placements. In a comparison of the two AR-guided placements, the automatic-alignment method was as accurate as the manual method but more efficient. Because of some limitations, the AR-guided system cannot be recommended in a clinical setting until there is significant improvement of this technology.


2021 ◽  
Vol 12 ◽  
pp. 518
Author(s):  
Mohamed M. Arnaout ◽  
Magdy O. ElSheikh ◽  
Mansour A. Makia

Background: Transpedicular screws are extensively utilized in lumbar spine surgery. The placement of these screws is typically guided by anatomical landmarks and intraoperative fluoroscopy. Here, we utilized 2-week postoperative computed tomography (CT) studies to confirm the accuracy/inaccuracy of lumbar pedicle screw placement in 145 patients and correlated these findings with clinical outcomes. Methods: Over 6 months, we prospectively evaluated the location of 612 pedicle screws placed in 145 patients undergoing instrumented lumbar fusions addressing diverse pathology with instability. Routine anteroposterior and lateral plain radiographs were obtained 48 h after the surgery, while CT scans were obtained at 2 postoperative weeks (i.e., ideally these should have been performed intraoperatively or within 24–48 h of surgery). Results: Of the 612 screws, minor misplacement of screws (≤2 mm) was seen in 104 patients, moderate misplacement in 34 patients (2–4 mm), and severe misplacement in 7 patients (>4 mm). Notably, all the latter 7 (4.8% of the 145) patients required repeated operative intervention. Conclusion: Transpedicular screw insertion in the lumbar spine carries the risks of pedicle medial/lateral violation that is best confirmed on CT rather than X-rays/fluoroscopy alone. Here, we additional found 7 patients (4.8%) who with severe medial/lateral pedicle breach who warranting repeated operative intervention. In the future, CT studies should be performed intraoperatively or within 24–48 h of surgery to confirm the location of pedicle screws and rule in our out medial or lateral pedicle breaches.


2013 ◽  
Vol 18 (5) ◽  
pp. 479-483 ◽  
Author(s):  
Eric W. Nottmeier ◽  
Stephen M. Pirris

Object Transvertebral pedicle screws have successfully been used in the treatment of high-grade L5–S1 spondylolisthesis. An advantage of transvertebral pedicle screws is the purchase of multiple cortical layers across 2 vertebrae, thereby increasing the stability of the construct. At the lumbosacral junction, transvertebral pedicle screws have been shown to be biomechanically superior to pedicle screws placed in the standard fashion. The use of transvertebral pedicle screws at spinal levels other than L5–S1 has not been reported in the literature. The authors describe their technique of transvertebral pedicle screw placement in the thoracic spine using 3D image guidance. Methods Twelve patients undergoing cervicothoracic or thoracolumbar fusion had 41 thoracic transvertebral pedicle screws placed across 26 spinal levels using this technique. Indications for placement of thoracic transvertebral pedicle screws in earlier cases included osteoporosis and pedicle screw salvage. However, in subsequent cases screws were placed in patients undergoing multilevel thoracolumbar fusion without osteoporosis, particularly near the top of the construct. Image guidance in this study was accomplished using the Medtronic StealthStation S7 image guidance system used in conjunction with the O-arm. All patients were slated to undergo postoperative CT scanning at approximately 4–6 months for fusion assessment, which also allowed for grading of the transvertebral pedicle screws. Results No thoracic transvertebral pedicle screw placed in this study had to be replaced or repositioned after intraoperative review of the cone beam CT scans. Review of the postoperative CT scans revealed all transvertebral screws to be across the superior disc space with the tips in the superior vertebral body. Six pedicle screws were placed using the in-out-in technique in patients with narrow pedicles, leaving 35 screws that underwent breach analysis. No pedicle breach was noted in 34 of 35 screws. A Grade 1 (< 2 mm) medial breach was noted in 1 screw without clinical consequence. Solid fusion was observed across 25 of 26 spinal levels that underwent transvertebral screw placement including 7 spinal levels located at the top of a multilevel construct. Conclusions This report describes the authors' initial in vivo experience with the 3D image-guided placement of 41 thoracic transvertebral pedicle screws. Advantages of thoracic transvertebral screws include the purchase of 2 vertebral segments across multiple cortical layers. A high fusion rate was observed across spinal levels in which transvertebral screws were placed. A formal biomechanical study is needed to assess the biomechanical advantages of this technique and is currently being planned.


2010 ◽  
Vol 13 (4) ◽  
pp. 509-515 ◽  
Author(s):  
Cary Idler ◽  
Kevin W. Rolfe ◽  
Josef E. Gorek

Object This study was conducted to assess the in vivo safety and accuracy of percutaneous lumbar pedicle screw placement using the owl's-eye view of the pedicle axis and a new guidance technology system that facilitates orientation of the C-arm into the appropriate fluoroscopic view and the pedicle cannulation tool in the corresponding trajectory. Methods A total of 326 percutaneous pedicle screws were placed from L-3 to S-1 in 85 consecutive adult patients. Placement was performed using simple coaxial imaging of the pedicle with the owl's-eye fluoroscopic view. NeuroVision, a new guidance system using accelerometer technology, helped align the C-arm trajectory into the owl's-eye view and the cannulation tool in the same trajectory. Postoperative fine-cut CT scans were acquired to assess screw position. Medical records were reviewed for complications. Results Five of 326 screws breached a pedicle cortex—all breaches were less than 2 mm—for an accuracy rate of 98.47%. Five screws violated an adjacent facet joint. All were at the S-1 superior facet and included in a fusion. No screw violated an adjacent mobile facet or disc space. There were no cases of new or worsening neurological symptoms or deficits for an overall clinical accuracy of 100%. Conclusions The owl's-eye technique of coaxial pedicle imaging with the C-arm fluoroscopy, facilitated by NeuroVision, is a safe and accurate means by which to place percutaneous pedicle screws for degenerative conditions of the lumbar spine. This is the largest series reported to use the oblique or owl's-eye projection for percutaneous pedicle screw insertion. The accuracy of percutaneous screw insertion with this technique meets or exceeds that of other reported clinical series or techniques.


2011 ◽  
Vol 14 (5) ◽  
pp. 664-669 ◽  
Author(s):  
Husam Alhabib ◽  
Andrew Nataraj ◽  
Mohammed Khashab ◽  
James Mahood ◽  
Frank Kortbeek ◽  
...  

Object Pedicle screw fixation is a mainstay of thoracolumbar stabilization. Screw insertion using anatomical landmarks and fluoroscopy is common but can be technically challenging and generally involves substantial exposure to ionizing radiation. Computerized navigation has been reported to improve accuracy but is expensive and complex. The authors undertook this study to evaluate these 3 methods in comparison with a fourth technique using standard cervical distractor screws to mark the entry point and trajectory. Methods Four cadaveric human spines were used for this study. After an initial CT scan, 34 pedicle screws were inserted in each intact spine from T-1 to L-5 using the following 4 screw insertion guidance techniques (1 technique per specimen): use of anatomical landmarks, use of cervical distractor screws and spot fluoroscopy, fluoroscopy-based navigation, and fluoroscopy- and CT-based navigation (using merged imaging data). Postprocedural CT and anatomical dissection were then performed to evaluate screw position for site and degree of breach. Results The cervical distractor screw method had a breach rate of 5.9% versus 29.4%, 32.4%, and 20.6% for use of anatomical landmarks, fluoroscopic navigation, and fluoroscopic-CT navigation, respectively (p < 0.05). There is also a significant association between degree of medial and distal breach and the method of screw insertion (p < 0.05). Conclusions Cervical distractor screws as pedicle markers offer favorable insertion accuracy and reduction of radiation exposure compared with the other 3 methods used in clinical practice.


2017 ◽  
Vol 42 (5) ◽  
pp. E14 ◽  
Author(s):  
Granit Molliqaj ◽  
Bawarjan Schatlo ◽  
Awad Alaid ◽  
Volodymyr Solomiichuk ◽  
Veit Rohde ◽  
...  

OBJECTIVEThe quest to improve the safety and accuracy and decrease the invasiveness of pedicle screw placement in spine surgery has led to a markedly increased interest in robotic technology. The SpineAssist from Mazor is one of the most widely distributed robotic systems. The aim of this study was to compare the accuracy of robot-guided and conventional freehand fluoroscopy-guided pedicle screw placement in thoracolumbar surgery.METHODSThis study is a retrospective series of 169 patients (83 women [49%]) who underwent placement of pedicle screw instrumentation from 2007 to 2015 in 2 reference centers. Pathological entities included degenerative disorders, tumors, and traumatic cases. In the robot-assisted cohort (98 patients, 439 screws), pedicle screws were inserted with robotic assistance. In the freehand fluoroscopy-guided cohort (71 patients, 441 screws), screws were inserted using anatomical landmarks and lateral fluoroscopic guidance. Patients treated before 2009 were included in the fluoroscopy cohort, whereas those treated since mid-2009 (when the robot was acquired) were included in the robot cohort. Since then, the decision to operate using robotic assistance or conventional freehand technique has been based on surgeon preference and logistics. The accuracy of screw placement was assessed based on the Gertzbein-Robbins scale by a neuroradiologist blinded to treatment group. The radiological slice with the largest visible deviation from the pedicle was chosen for grading. A pedicle breach of 2 mm or less was deemed acceptable (Grades A and B) while deviations greater than 2 mm (Grades C, D, and E) were classified as misplacements.RESULTSIn the robot-assisted cohort, a perfect trajectory (Grade A) was observed for 366 screws (83.4%). The remaining screws were Grades B (n = 44 [10%]), C (n = 15 [3.4%]), D (n = 8 [1.8%]), and E (n = 6 [1.4%]). In the fluoroscopy-guided group, a completely intrapedicular course graded as A was found in 76% (n = 335). The remaining screws were Grades B (n = 57 [12.9%]), C (n = 29 [6.6%]), D (n = 12 [2.7%]), and E (n = 8 [1.8%]). The proportion of non-misplaced screws (corresponding to Gertzbein-Robbins Grades A and B) was higher in the robot-assisted group (93.4%) than the freehand fluoroscopy group (88.9%) (p = 0.005).CONCLUSIONSThe authors’ retrospective case review found that robot-guided pedicle screw placement is a safe, useful, and potentially more accurate alternative to the conventional freehand technique for the placement of thoracolumbar spinal instrumentation.


2022 ◽  
Vol 52 (1) ◽  
pp. E8

OBJECTIVE Pedicle screw insertion for stabilization after lumbar fusion surgery is commonly performed by spine surgeons. With the advent of navigation technology, the accuracy of pedicle screw insertion has increased. Robotic guidance has revolutionized the placement of pedicle screws with 2 distinct radiographic registration methods, the scan-and-plan method and CT-to-fluoroscopy method. In this study, the authors aimed to compare the accuracy and safety of these methods. METHODS A retrospective chart review was conducted at 2 centers to obtain operative data for consecutive patients who underwent robot-assisted lumbar pedicle screw placement. The newest robotic platform (Mazor X Robotic System) was used in all cases. One center used the scan-and-plan registration method, and the other used CT-to-fluoroscopy for registration. Screw accuracy was determined by applying the Gertzbein-Robbins scale. Fluoroscopic exposure times were collected from radiology reports. RESULTS Overall, 268 patients underwent pedicle screw insertion, 126 patients with scan-and-plan registration and 142 with CT-to-fluoroscopy registration. In the scan-and-plan cohort, 450 screws were inserted across 266 spinal levels (mean 1.7 ± 1.1 screws/level), with 446 (99.1%) screws classified as Gertzbein-Robbins grade A (within the pedicle) and 4 (0.9%) as grade B (< 2-mm deviation). In the CT-to-fluoroscopy cohort, 574 screws were inserted across 280 lumbar spinal levels (mean 2.05 ± 1.7 screws/ level), with 563 (98.1%) grade A screws and 11 (1.9%) grade B (p = 0.17). The scan-and-plan cohort had nonsignificantly less fluoroscopic exposure per screw than the CT-to-fluoroscopy cohort (12 ± 13 seconds vs 11.1 ± 7 seconds, p = 0.3). CONCLUSIONS Both scan-and-plan registration and CT-to-fluoroscopy registration methods were safe, accurate, and had similar fluoroscopy time exposure overall.


2016 ◽  
Vol 15 (4) ◽  
pp. 290-294 ◽  
Author(s):  
MARCELO ITALO RISSO NETO ◽  
SYLVIO MISTRO NETO ◽  
ROBERTO ROSSANEZ ◽  
GUILHERME REBECHI ZUIANI ◽  
IVAN GUIDOLIN VEIGA ◽  
...  

ABSTRACT Objective: To evaluate whether the presence of osteolysis around the pedicle screws affects the quality of life of patients who underwent posterolateral arthrodesis of the lumbosacral spine. Methods: A retrospective study of patients undergoing lumbar posterolateral or lumbosacral arthrodesis due to spinal degenerative disease. CT scans of the operated segments were performed at intervals of 45, 90, 180, and 360 postoperatively. In these tests, the presence of a peri-implant radiolucent halo was investigated, which was considered present when greater than 1mm in the coronal section. Concurrently with the completion of CT scans, the participants completed the questionnaire Oswestry Disability Index (ODI) to assess the degree of disability of the patients. Results: A total of 38 patients were evaluated, and 14 (36.84%) of them showed some degree of osteolysis around at least one pedicle screw at the end of follow-up. Of the 242 analyzed screws, 27 (11.15%) had osteolysis in the CT coronal section, with the majority of these occurrences located at the most distal level segment of the arthrodesis. There was no correlation between the presence of the osteolysis to the quality of life of patients. The quality of life has significantly improved when comparing the preoperative results with the postoperative results at different times of application of ODI. This improvement in ODI maintains linearity over time. Conclusion: There is no correlation between the presence of peri-implant osteolysis to the quality of life of patients undergoing lumbar or posterolateral lumbosacral arthrodesis in the follow-up period up to 360 days. The quality of life in postoperative has significantly improvement when compared to the preoperative period.


2002 ◽  
Vol 97 (1) ◽  
pp. 7-12 ◽  
Author(s):  
Kevin T. Foley ◽  
Sanjay K. Gupta

Object. Standard techniques for pedicle screw fixation of the lumbar spine involve open exposures and extensive muscle dissection. The purpose of this study was to report the initial clinical experience with a novel device for percutaneous posterior fixation of the lumbar spine. Methods. An existing multiaxial lumbar pedicle screw system was modified to allow screws to be placed percutaneously by using an extension sleeve that permits remote manipulation of the polyaxial screw heads and remote engagement of the screw-locking mechanism. A unique rod-insertion device was developed that linked to the screw extension sleeves, allowing for a precut and -contoured rod to be placed through a small stab wound. Because the insertion device relies on the geometrical constraint of the rod pathway through the screw heads, minimal manipulation is required to place the rods in a standard submuscular position, there is essentially no muscle dissection, and the need for direct visual feedback is avoided. Twelve patients (six men and six women) who ranged in age from 23 to 68 years underwent pedicle screw fixation in which the rod-insertion device was used. Spondylolisthesis was present in 10 patients and osseous nonunion of a prior interbody fusion was present in two. All patients underwent successful percutaneous fixation. Ten patients underwent single-level fusions (six at L5—S1, three at L4–5, and one at L2–3), and two underwent two-level fusions (one from L3–5 and the other from L4—S1). The follow-up period ranged from 10 to 19 months (mean 13.8 months). Conclusions. Although percutaneous lumbar pedicle screw placement has been described previously, longitudinal connector (rod or plate) insertion has been more problematic. The device used in this study allows for straightforward placement of lumbar pedicle screws and rods through percutaneous stab wounds. Paraspinous tissue trauma is minimized without compromising the quality of spinal fixation. Preliminary experience involving the use of this device has been promising.


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