scholarly journals Initial Intraoperative Experience with Robotic-Assisted Pedicle Screw Placement with Cirq® Robotic Alignment: An Evaluation of the First 70 Screws

2021 ◽  
Vol 10 (24) ◽  
pp. 5725
Author(s):  
Mirza Pojskić ◽  
Miriam Bopp ◽  
Christopher Nimsky ◽  
Barbara Carl ◽  
Benjamin Saβ
Keyword(s):  
Pedicle Screw ◽  
Intraoperative Imaging ◽  
Pedicle Screws ◽  
Robotic Arm ◽  
Screw Placement ◽  
Angular Deviation ◽  
Pedicle Screw Placement ◽  
Robotic Assisted ◽  
The Mean ◽  
Mean Time

Background: Robot-guided spine surgery is based on a preoperatively planned trajectory that is reproduced in the operating room by the robotic device. This study presents our initial experience with thoracolumbar pedicle screw placement using Brainlab’s Cirq® surgeon-controlled robotic arm (BrainLab, Munich, Germany). Methods: All patients who underwent robotic-assisted implantation of pedicle screws in the thoracolumbar spine were included in the study. Our workflow, consisting of preoperative imagining, screw planning, intraoperative imaging with automatic registration, fusion of the preoperative and intraoperative imaging with a review of the preplanned screw trajectories, robotic-assisted insertion of K-wires, followed by a fluoroscopy-assisted insertion of pedicle screws and control iCT scan, is described. Results: A total of 12 patients (5 male and 7 females, mean age 67.4 years) underwent 13 surgeries using the Cirq® Robotic Alignment Module for thoracolumbar pedicle screw implantation. Spondylodiscitis, metastases, osteoporotic fracture, and spinal canal stenosis were detected. A total of 70 screws were implanted. The mean time per screw was 08:27 ± 06:54 min. The mean time per screw for the first 7 surgeries (first 36 screws) was 16:03 ± 09:32 min and for the latter 6 surgeries (34 screws) the mean time per screw was 04:35 ± 02:11 min (p < 0.05). Mean entry point deviation was 1.9 ± 1.23 mm, mean deviation from the tip of the screw was 2.61 ± 1.6 mm and mean angular deviation was 3.5° ± 2°. For screw-placement accuracy we used the CT-based Gertzbein and Robbins System (GRS). Of the total screws, 65 screws were GRS A screws (92.85%), one screw was a GRS B screw, and two further screws were grade C. Two screws were D screws (2.85%) and underwent intraoperative revision. There were no perioperative deficits. Conclusion: Brainlab’s Cirq® Robotic Alignment surgeon-controlled robotic arm is a safe and beneficial method for accurate thoracolumbar pedicle screw placement with high accuracy.

scholarly journals Three-dimensional assessment of robot-assisted pedicle screw placement accuracy and instrumentation reliability based on a preplanned trajectory

2020 ◽  
Vol 33 (4) ◽  
pp. 519-528
Author(s):  
Bowen Jiang ◽  
Zach Pennington ◽  
Alex Zhu ◽  
Stavros Matsoukas ◽  
A. Karim Ahmed ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Tertiary Care ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Lumbosacral Spine ◽  
Grading System ◽  
Angular Deviation ◽  
Pedicle Screw Placement ◽  
Placement Accuracy ◽  
The Mean

OBJECTIVERobotic spine surgery systems are increasingly used in the US market. As this technology gains traction, however, it is necessary to identify mechanisms that assess its effectiveness and allow for its continued improvement. One such mechanism is the development of a new 3D grading system that can serve as the foundation for error-based learning in robot systems. Herein the authors attempted 1) to define a system of providing accuracy data along all three pedicle screw placement axes, that is, cephalocaudal, mediolateral, and screw long axes; and 2) to use the grading system to evaluate the mean accuracy of thoracolumbar pedicle screws placed using a single commercially available robotic system.METHODSThe authors retrospectively reviewed a prospectively maintained, IRB-approved database of patients at a single tertiary care center who had undergone instrumented fusion of the thoracic or lumbosacral spine using robotic assistance. Patients with preoperatively planned screw trajectories and postoperative CT studies were included in the final analysis. Screw accuracy was measured as the net deviation of the planned trajectory from the actual screw trajectory in the mediolateral, cephalocaudal, and screw long axes.RESULTSThe authors identified 47 patients, 51% male, whose pedicles had been instrumented with a total of 254 screws (63 thoracic, 191 lumbosacral). The patients had a mean age of 61.1 years and a mean BMI of 30.0 kg/m2. The mean screw tip accuracies were 1.3 ± 1.3 mm, 1.2 ± 1.1 mm, and 2.6 ± 2.2 mm in the mediolateral, cephalocaudal, and screw long axes, respectively, for a net linear deviation of 3.6 ± 2.3 mm and net angular deviation of 3.6° ± 2.8°. According to the Gertzbein-Robbins grading system, 184 screws (72%) were classified as grade A and 70 screws (28%) as grade B. Placement of 100% of the screws was clinically acceptable.CONCLUSIONSThe accuracy of the discussed robotic spine system is similar to that described for other surgical systems. Additionally, the authors outline a new method of grading screw placement accuracy that measures deviation in all three relevant axes. This grading system could provide the error signal necessary for unsupervised machine learning by robotic systems, which would in turn support continued improvement in instrumentation placement accuracy.

Clinical Assessment of Percutaneous Lumbar Pedicle Screw Placement Using the O-Arm Multidimensional Surgical Imaging System

Neurosurgery ◽  
2011 ◽  
Vol 70 (4) ◽  
pp. 990-995 ◽  
Author(s):  
John K. Houten ◽  
Rani Nasser ◽  
Nrupen Baxi
Keyword(s):  
Minimally Invasive ◽  
Pedicle Screw ◽  
Imaging System ◽  
Intraoperative Imaging ◽  
Lumbar Fusion ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Pedicle Screw Placement ◽  
Percutaneous Pedicle Screw ◽  
Clinical Series

Abstract BACKGROUND: Increasing popularity of minimally invasive surgery for lumbar fusion has led to dependence upon intraoperative fluoroscopy for pedicle screw placement, because limited muscle dissection does not expose the bony anatomy necessary for traditional, freehand techniques nor for registration steps in image-guidance techniques. This has raised concerns about cumulative radiation exposure for both surgeon and operating room staff. The recent introduction of the O-arm Multidimensional Surgical Imaging System allows for percutaneous placement of pedicle screws, but there is limited clinical experience with the technique and data examining its accuracy. OBJECTIVE: We present the first large clinical series of percutaneous screw placement using navigation of O-arm imaging and compare the results with the fluoroscopy-guided method. METHODS: A retrospective review of a 24-month period identified patients undergoing minimally invasive lumbar interbody fusion. The O-arm was introduced in the middle of this period and was used for all subsequent patients. Accuracy of screw placement was assessed by examination of axial computed tomography or O-arm scans. RESULTS: The fluoroscopy group included 141 screws in 42 patients, and the O-arm group included 205 screws in 52 patients. The perforation rate was 12.8% in the fluoroscopy group and 3% in the O-arm group (P &lt; .001). Single-level O-arm procedures took a mean 200 (153–241) minutes, whereas fluoroscopy took 221 (178–302) minutes (P &lt; .03). CONCLUSION: Percutaneous pedicle screw placement with the O-arm Multidimensional Intraoperative Imaging System is a safe and effective technique and provided improved overall accuracy and reduced operative time compared with conventional fluoroscopic techniques.

scholarly journals First in-human report of the clinical accuracy of thoracolumbar percutaneous pedicle screw placement using augmented reality guidance

2021 ◽  
Vol 51 (2) ◽  
pp. E10
Author(s):  
Alexander T. Yahanda ◽  
Emelia Moore ◽  
Wilson Z. Ray ◽  
Brenton Pennicooke ◽  
Jack W. Jennings ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Lower Extremity ◽  
Pedicle Screw ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Spinal Tumors ◽  
Pedicle Screw Placement ◽  
Percutaneous Pedicle Screw ◽  
Clinical Accuracy ◽  
The Mean

OBJECTIVE Augmented reality (AR) is an emerging technology that has great potential for guiding the safe and accurate placement of spinal hardware, including percutaneous pedicle screws. The goal of this study was to assess the accuracy of 63 percutaneous pedicle screws placed at a single institution using an AR head-mounted display (ARHMD) system. METHODS Retrospective analyses were performed for 9 patients who underwent thoracic and/or lumbar percutaneous pedicle screw placement guided by ARHMD technology. Clinical accuracy was assessed via the Gertzbein-Robbins scale by the authors and by an independent musculoskeletal radiologist. Thoracic pedicle subanalysis was also performed to assess screw accuracy based on pedicle morphology. RESULTS Nine patients received thoracic or lumbar AR-guided percutaneous pedicle screws. The mean age at the time of surgery was 71.9 ± 11.5 years and the mean number of screws per patient was 7. Indications for surgery were spinal tumors (n = 4, 44.4%), degenerative disease (n = 3, 33.3%), spinal deformity (n = 1, 11.1%), and a combination of deformity and infection (n = 1, 11.1%). Presenting symptoms were most commonly low-back pain (n = 7, 77.8%) and lower-extremity weakness (n = 5, 55.6%), followed by radicular lower-extremity pain, loss of lower-extremity sensation, or incontinence/urinary retention (n = 3 each, 33.3%). In all, 63 screws were placed (32 thoracic, 31 lumbar). The accuracy for these screws was 100% overall; all screws were Gertzbein-Robbins grade A or B (96.8% grade A, 3.2% grade B). This accuracy was achieved in the thoracic spine regardless of pedicle cancellous bone morphology. CONCLUSIONS AR-guided surgery demonstrated a 100% accuracy rate for the insertion of 63 percutaneous pedicle screws in 9 patients (100% rate of Gertzbein-Robbins grade A or B screw placement). Using an ARHMS system for the placement of percutaneous pedicle screws showed promise, but further validation using a larger cohort of patients across multiple surgeons and institutions will help to determine the true accuracy enabled by this technology.

Less Invasive Pediatric Spinal Deformity Surgery: The Case for Robotic-Assisted Placement of Pedicle Screws

2021 ◽  
pp. 155633162110278
Author(s):  
Kyle W. Morse ◽  
Hila Otremski ◽  
Kira Page ◽  
Roger F. Widmann
Keyword(s):  
Pedicle Screw ◽  
Current Literature ◽  
Spinal Deformity ◽  
Spinal Surgery ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Pedicle Screw Placement ◽  
Robotic Assisted ◽  
Less Invasive ◽  
Spinal Deformity Surgery

Introduction: Pediatric spinal deformity involves a complex 3-dimensional (3D) deformity that increases the risk of pedicle screw placement due to the close proximity of neurovascular structures. To increase screw accuracy, improve patient safety, and minimize surgical complications, the placement of pedicle screws is evolving from freehand techniques to computer-assisted navigation and to the introduction of robotic-assisted placement. Purpose: The aim of this review was to review the current literature on the use of robotic navigation in pediatric spinal deformity surgery to provide both an error analysis of these techniques and to provide recommendations to ensure its safe application. Methods: A narrative review was conducted in April 2021 using the MEDLINE (PubMed) database. Studies were included if they were peer-reviewed retrospective or prospective studies, included pediatric patients, included a primary diagnosis of pediatric spine deformity, utilized robotic-assisted spinal surgery techniques, and reported thoracic or lumbar pedicle screw breach rates or pedicle screw malpositioning. Results: In the few studies published on the use of robotic techniques in pediatric spinal deformity surgery, several found associations between the technology and increased rates of screw placement accuracy, reduced rates of breach, and minimal complications. All were retrospective studies. Conclusions: Current literature is of a low level of evidence; nonetheless, the findings suggest the accuracy and safety of robotic-assisted spinal surgery in pediatric pedicle screw placement. The introduction of robotics may drive further advances in less invasive pediatric spinal deformity surgery. Further study is warranted.

scholarly journals Does robot-assisted navigation influence pedicle screw selection and accuracy in minimally invasive spine surgery?

2022 ◽  
Vol 52 (1) ◽  
pp. E4
Keyword(s):  
Minimally Invasive ◽  
Pedicle Screw ◽  
Surgical Navigation ◽  
Lumbar Fusion ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Robotic Assistance ◽  
Pedicle Screw Placement ◽  
Screw Length ◽  
The Mean

OBJECTIVE The accuracy of percutaneous pedicle screw placement has increased with the advent of robotic and surgical navigation technologies. However, the effect of robotic intraoperative screw size and trajectory templating remains unclear. The purpose of this study was to compare pedicle screw sizes and accuracy of placement using robotic navigation (RN) versus skin-based intraoperative navigation (ION) alone in minimally invasive lumbar fusion procedures. METHODS A retrospective cohort study was conducted using a single-institution registry of spine procedures performed over a 4-year period. Patients who underwent 1- or 2-level primary or revision minimally invasive surgery (MIS)–transforaminal lumbar interbody fusion (TLIF) with pedicle screw placement, via either robotic assistance or surgical navigation alone, were included. Demographic, surgical, and radiographic data were collected. Pedicle screw type, quantity, length, diameter, and the presence of endplate breach or facet joint violation were assessed. Statistical analysis using the Student t-test and chi-square test was performed to evaluate the differences in pedicle screw sizes and the accuracy of placement between both groups. RESULTS Overall, 222 patients were included, of whom 92 underwent RN and 130 underwent ION MIS-TLIF. A total of 403 and 534 pedicle screws were placed with RN and ION, respectively. The mean screw diameters were 7.25 ± 0.81 mm and 6.72 ± 0.49 mm (p < 0.001) for the RN and ION groups, respectively. The mean screw length was 48.4 ± 4.48 mm in the RN group and 45.6 ± 3.46 mm in the ION group (p < 0.001). The rates of “ideal” pedicle screws in the RN and ION groups were comparable at 88.5% and 88.4% (p = 0.969), respectively. The overall screw placement was also similar. The RN cohort had 63.7% screws rated as good and 31.4% as acceptable, while 66.1% of ION-placed screws had good placement and 28.7% had acceptable placement (p = 0.661 and p = 0.595, respectively). There was a significant reduction in high-grade breaches in the RN group (0%, n = 0) compared with the ION group (1.2%, n = 17, p = 0.05). CONCLUSIONS The results of this study suggest that robotic assistance allows for placement of screws with greater screw diameter and length compared with surgical navigation alone, although with similarly high accuracy. These findings have implied that robotic platforms may allow for safe placement of the “optimal screw,” maximizing construct stability and, thus, the ability to obtain a successful fusion.

The accuracy of pedicle screw placement using intraoperative image guidance systems

2014 ◽  
Vol 20 (2) ◽  
pp. 196-203 ◽  
Author(s):  
Alexander Mason ◽  
Renee Paulsen ◽  
Jason M. Babuska ◽  
Sharad Rajpal ◽  
Sigita Burneikiene ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Image Guidance ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Data Sets ◽  
Pedicle Screw Placement ◽  
Fluoroscopic Image ◽  
Fluoroscopic Navigation ◽  
Guidance Systems ◽  
Accuracy Rates

Object Several retrospective studies have demonstrated higher accuracy rates and increased safety for navigated pedicle screw placement than for free-hand techniques; however, the accuracy differences between navigation systems has not been extensively studied. In some instances, 3D fluoroscopic navigation methods have been reported to not be more accurate than 2D navigation methods for pedicle screw placement. The authors of this study endeavored to identify if 3D fluoroscopic navigation methods resulted in a higher placement accuracy of pedicle screws. Methods A systematic analysis was conducted to examine pedicle screw insertion accuracy based on the use of 2D, 3D, and conventional fluoroscopic image guidance systems. A PubMed and MEDLINE database search was conducted to review the published literature that focused on the accuracy of pedicle screw placement using intraoperative, real-time fluoroscopic image guidance in spine fusion surgeries. The pedicle screw accuracy rates were segregated according to spinal level because each spinal region has individual anatomical and morphological variations. Descriptive statistics were used to compare the pedicle screw insertion accuracy rate differences among the navigation methods. Results A total of 30 studies were included in the analysis. The data were abstracted and analyzed for the following groups: 12 data sets that used conventional fluoroscopy, 8 data sets that used 2D fluoroscopic navigation, and 20 data sets that used 3D fluoroscopic navigation. These studies included 1973 patients in whom 9310 pedicle screws were inserted. With conventional fluoroscopy, 2532 of 3719 screws were inserted accurately (68.1% accuracy); with 2D fluoroscopic navigation, 1031 of 1223 screws were inserted accurately (84.3% accuracy); and with 3D fluoroscopic navigation, 4170 of 4368 screws were inserted accurately (95.5% accuracy). The accuracy rates when 3D was compared with 2D fluoroscopic navigation were also consistently higher throughout all individual spinal levels. Conclusions Three-dimensional fluoroscopic image guidance systems demonstrated a significantly higher pedicle screw placement accuracy than conventional fluoroscopy or 2D fluoroscopic image guidance methods.

scholarly journals Anatomic considerations for C2 pedicle screw placement: the use of computerized tomography measurements

2009 ◽  
Vol 8 (1) ◽  
pp. 80-83
Author(s):  
Adebukoa Onibokun ◽  
Simona Bistazzoni ◽  
Marco Sassi ◽  
Larry T. Khoo
Keyword(s):  
Pedicle Screw ◽  
Computerized Tomography ◽  
Preoperative Planning ◽  
Screw Placement ◽  
Pedicle Screw Placement ◽  
C2 Pedicle Screw ◽  
Anatomical Knowledge ◽  
Axial Ct ◽  
The Mean ◽  
Pedicle Width

OBJECTIVE: more detailed anatomical knowledge of the C2 pedicle is required to optimize and minimize the risk of screw placement. The aim of this study was to evaluate the linear and angular dimensions of the true C2 pedicle using axial CT. METHODS: ninety three patients (47 males, 46 females mean age 48 years) who had cervical spinal CT imaging performed were evaluated for this study. Axial images of the C2 pedicle were selected and the following pedicle parameters were determined: pedicle width (PW, the mediolateral diameter of the pedicle isthmus, perpendicular to the pedicle axis) and pedicle transverse angle (PTA, that is, the angle between the pedicle axis and the midline of the vertebral body). RESULTS: the overall mean pedicle width was 5.8 1.2mm. The mean pedicle width in males (6.01.3mm) was greater than that in the female subjects (5.6 1.1mm). This difference was not found to be statistically significant (p=.6790). The overall mean pedicle transverse angle was 43.93.9 degrees. The mean PTA in males was 43.23.8 degrees, while that in females was 44.73.7 degrees. CONCLUSION: preoperative planning is absolutely mandatory, particularly in determining not only screw trajectory, but in analyzing individual patient anatomy and reception to a C2 pedicle screw.

scholarly journals Utility of intraoperative electromyography in placing C7 pedicle screws

2020 ◽  
Vol 32 (6) ◽  
pp. 891-899 ◽  
Author(s):  
Jonathan J. Rasouli ◽  
Brooke T. Kennamer ◽  
Frank M. Moore ◽  
Alfred Steinberger ◽  
Kevin C. Yao ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Pedicle Screw ◽  
Thoracolumbar Spine ◽  
Pedicle Screws ◽  
Neurological Injury ◽  
Screw Placement ◽  
Pedicle Screw Placement ◽  
Data Set ◽  
Subaxial Cervical Spine ◽  
Increased Risk

OBJECTIVEThe C7 vertebral body is morphometrically unique; it represents the transition from the subaxial cervical spine to the upper thoracic spine. It has larger pedicles but relatively small lateral masses compared to other levels of the subaxial cervical spine. Although the biomechanical properties of C7 pedicle screws are superior to those of lateral mass screws, they are rarely placed due to increased risk of neurological injury. Although pedicle screw stimulation has been shown to be safe and effective in determining satisfactory screw placement in the thoracolumbar spine, there are few studies determining its utility in the cervical spine. Thus, the purpose of this study was to determine the feasibility, clinical reliability, and threshold characteristics of intraoperative evoked electromyographic (EMG) stimulation in determining satisfactory pedicle screw placement at C7.METHODSThe authors retrospectively reviewed a prospectively collected data set. All adult patients who underwent posterior cervical decompression and fusion with placement of C7 pedicle screws at the authors’ institution between January 2015 and March 2019 were identified. Demographic, clinical, neurophysiological, operative, and radiographic data were gathered. All patients underwent postoperative CT scanning, and the position of C7 pedicle screws was compared to intraoperative neurophysiological data.RESULTSFifty-one consecutive C7 pedicle screws were stimulated and recorded intraoperatively in 25 consecutive patients. Based on EMG findings, 1 patient underwent intraoperative repositioning of a C7 pedicle screw, and 1 underwent removal of a C7 pedicle screw. CT scans demonstrated ideal placement of the C7 pedicle screw in 40 of 43 instances in which EMG stimulation thresholds were > 15 mA. In the remaining 3 cases the trajectories were suboptimal but safe. When the screw stimulation thresholds were between 11 and 15 mA, 5 of 6 screws were suboptimal but safe, and in 1 instance was potentially dangerous. In instances in which the screw stimulated at thresholds ≤ 10 mA, all trajectories were potentially dangerous with neural compression.CONCLUSIONSIdeal C7 pedicle screw position strongly correlated with EMG stimulation thresholds > 15 mA. In instances, in which the screw stimulates at values between 11 and 15 mA, screw trajectory exploration is recommended. Screws with thresholds ≤ 10 mA should always be explored, and possibly repositioned or removed. In conjunction with other techniques, EMG threshold testing is a useful and safe modality in determining appropriate C7 pedicle screw placement.

scholarly journals Confirmation of accuracy/inaccuracy of lumbar pedicle screw placement using postoperative computed tomography

2021 ◽  
Vol 12 ◽  
pp. 518
Author(s):  
Mohamed M. Arnaout ◽  
Magdy O. ElSheikh ◽  
Mansour A. Makia
Keyword(s):  
Computed Tomography ◽  
Lumbar Spine ◽  
Pedicle Screw ◽  
Pedicle Screws ◽  
Operative Intervention ◽  
Screw Placement ◽  
Lumbar Spine Surgery ◽  
Pedicle Screw Placement ◽  
Lumbar Pedicle ◽  
Ct Studies

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.

scholarly journals Anatomical and radiologic characteristics of isthmus parameters in guiding pedicle screw placement

2018 ◽  
Vol 46 (6) ◽  
pp. 2386-2397 ◽  
Author(s):  
Paerhati Rexiti ◽  
Yakufu Abulizi ◽  
Aikeremujiang Muheremu ◽  
Shuiquan Wang ◽  
Maierdan Maimaiti ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Lumbar Spine Surgery ◽  
X Rays ◽  
Pedicle Screw Placement ◽  
Chinese Han ◽  
Before And After ◽  
Placement Accuracy ◽  
D Value

Objective To study the clinical application of lumbar isthmus parameters in guiding pedicle screw placement. Methods Lumbar isthmus parameters were measured in normal lumbar x-rays and cadaveric specimens from a Chinese Han population. Distance between the medial pedicle border and lateral isthmus border was recorded as a ‘D’ value and was compared between X-rays and cadavers. Orthopaedic surgeons estimated different distances (2–6 mm) and angles (5–20°), and bias ratios between estimated and real values were compared. Orthopaedic residents placed pedicle screws on cadaveric specimens before and after application of the ‘D’ value, and screw placement accuracy was compared. Results Except for L4 vertebrae, significant differences in the ‘D’ value were found between 25 cadaveric specimens and x-ray films from 120 patients. Distances and angles estimated by 40 surgeons were significantly different from all real values, except 2 mm distance. Accuracy of pedicle screw placement by six orthopaedic residents was significantly improved by applying the ‘D’ value. Conclusions Surgeon estimates of distance were more accurate than angle estimates. Addition of a ‘D’ value to conventional parameters may significantly improve pedicle screw placement accuracy in lumbar spine surgery.

Sign in / Sign up

Export Citation Format

Share Document