Percutaneous Lumbar Pedicle Screw Placement Aided by Computer-Assisted Fluoroscopy-Based Navigation

This study compares the accuracy rates of lumbar percutaneous pedicle screw placement (PPSP) using either 2-dimensional (2-D) fluoroscopic guidance or 3-dimensional (3-D) stereotactic navigation in the setting of minimally invasive spine surgery (MISS). This represents the largest single-operator study of its kind and first comprehensive review of 3-D stereotactic navigation in the setting of MISS. To examine differences in accuracy of lumbar pedicle screw placement using 2-D fluoroscopic navigation and 3-D stereotaxis in the setting of MISS. Surgeons increasingly rely upon advanced image guidance systems to guide minimally invasive PPSP. Three-dimensional stereotactic navigation with intraoperative computed tomography offers well-documented benefit in open surgical approaches. However, the utility of 3-D stereotaxis in the setting of MISS remains incompletely explored by few studies with limited patient numbers. A total of 599 consecutive patients underwent minimally invasive lumbar PPSP aided by 3-D stereotactic navigation. Postoperative imaging and medical records were analyzed for patient demographics, incidence and degree of pedicle breach, and other surgical complications. A total of 2132 screw were reviewed and compared with a meta-analysis created from published data regarding the placement of 4248 fluoroscopically navigated pedicle screws in the setting of MISS. In the 3-D navigation group, a total of 7 pedicle breaches occurred in 6 patients, corresponding to a per-person breach rate of 1.15% (6/518) and a per-screw breach rate of 0.33% (7/2132). Meta-analysis comprised of data from 10 independent studies showed overall breach risk of 13.1% when 2-D fluoroscopic navigation was utilized in MISS. This translates to a 99% decrease in odds of breach in the 3-D navigation technique versus the traditional 2-D-guided technique, with an odds ratio of 0.01, (95% confidence interval, 0.01-0.03), P<0.001. Three-dimensional stereotactic navigation based upon intraoperative computed tomography imaging offers markedly improved accuracy of percutaneous lumbar pedicle screw placement when used in the setting of MISS.

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. 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. 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. 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 < .001). Single-level O-arm procedures took a mean 200 (153-241) minutes, whereas fluoroscopy took 221 (178-302) minutes (P < .03). 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.

The authors sought to evaluate the feasibility and accuracy of three-dimensional (3D) fluoroscopic guidance for percutaneous placement of thoracic and lumbar pedicle screws in three cadaveric specimens. After attaching a percutaneous dynamic reference array to the surgical anatomy, an isocentric C-arm fluoroscope was used to obtain images of the region of interest. Light-emitting diodes attached to the C-arm unit were tracked using an electrooptical camera. The image data set was transferred to the image-guided workstation, which performed an automated registration. Using the workstation display, pedicle screw trajectories were planned. An image-guided drill guide was passed through a stab incision, and this was followed by sequential image-guided pedicle drilling, tapping, and screw placement. Pedicle screws of various diameters (range 4-6.5 mm) were placed in all pedicles greater than 4 mm in diameter. Postoperatively, thin-cut computerized tomography scans were obtained to determine the accuracy of screw placement. Eighty-nine (94.7%) of 94 percutaneous screws were placed completely within the cortical pedicle margins, including all 30 lumbar screws (100%) and 59 (92%) of 64 thoracic screws. The mean diameter of all thoracic pedicles was 6 mm (range 2.9-11 mm); the mean diameter of the five pedicles in which wall violations occurred was 4.6 mm (range 4.1-6.3 mm). Two of the violations were less than 2 mm beyond the cortex; the others were between 2 and 3 mm. Coupled with an image guidance system, 3D fluoroscopy allows highly accurate spinal navigation. Results of this study suggest that this technology will facilitate the application of minimally invasive techniques to the field of spine surgery.

Percutaneous pedicle screws are commonly used in minimally invasive spinal procedures. Traditional techniques of percutaneous pedicle screw placement have employed the use of multiplanar fluoroscopy and Kirschner wires (K-wires). The use of multiplanar fluoroscopy for the placement of percutaneous pedicle screws likely increases radiation exposure to the surgeon when compared to open techniques. K-wires can break or become bent during the procedure, making it difficult to insert and remove instrumentation over them. Additionally, there is also a risk of visceral or vascular injury with the use of K-wires. The authors present a novel method of percutaneous pedicle screw placement utilizing three-dimensional (3D) fluoroscopy-based image guidance in which K-wires are not used and there is minimal to no radiation exposure to the surgeon and operating room staff. Thirty-six screws were placed in 15 patients using this technique. An independent radiologist graded screw placement using computed tomographic (CT) scans and the breach rate of the percutaneous pedicle screws was compared to the breach rate of 33 pedicle screws placed contralaterally using the mini-open technique. No bony breach was noted by any screw in either group and no complications occurred in this study as a result of screw placement. Percutaneous pedicle screws can be placed accurately and safely using 3D image guidance without the use of K-wires. Little to no radiation exposure to the surgeon or OR staff occurs with this technique. No complications occurred in this study as a result of screw placement or image guidance.

Percutaneous pedicle screws are used to provide rigid internal fixation in minimally invasive spinal procedures and generally require the use of Kirchner wires (or K-wires) as a guide for screw insertion. K-wires can bend, break, advance, or pull out during the steps of pedicle preparation and screw insertion. This can lead to increased fluoroscopic and surgical times and potentially cause neurological, vascular, or visceral injury. The authors present their experience with a novel "K-wireless" percutaneous pedicle screw system that eliminates the inherent risks of K-wire use. A total of 100 screws were placed in 28 patients using the K-wireless percutaneous screw system. Postoperative dedicated spinal CT scans were performed in 25 patients to assess the accuracy of screw placement. Screw placement was graded A through D by 2 independent radiologists: A = within pedicle, B = breach < 2 mm, C = breach of 2-4 mm, and D = breach > 4 mm. Screw insertion and fluoroscopy times were also recorded in each case. Clinical complications associated with screw insertion were documented. A total of 100 K-wireless percutaneous pedicle screws were placed into the lumbosacral spine in 28 patients. Postoperative CT was performed in 25 patients, thus the placement of only 90 screws was assessed. Eighty-seven screws were placed within the pedicle confines (Grade A), and 3 violated the pedicle (2 Grade B [1 lateral, 1 medial] and 1 Grade D [medial]) for an overall accuracy rate of 96.7%. One patient required reoperation for screw repositioning due to a postoperative L-5 radiculopathy secondary to a Grade D medial breach at L-5. This patient experienced improvement of the radiculopathy after reoperation. Average screw insertion and fluoroscopy times were 6.92 minutes and 22.7 seconds per screw, respectively. The results of this study demonstrate that the placement of K-wireless percutaneous pedicle screws is technically feasible and can be performed accurately and safely with short procedure and fluoroscopy times.

ObjectiveThis study retrospectively assessed the accuracy of placement of lumbar pedicle screws placed by a single surgeon using a minimally-invasive, intra-operative CT-based computer navigated technique in combination with continuous electromyography (EMG) monitoring. The rates of incorrectly positioned screws were reviewed in the context of the surgeon's experience and learning curve.MethodsData was retrospectively reviewed from all consecutive minimally invasive lumbar fusions performed by the primary author over a period of over 4 years from April 2008 until October 2012. All cases that had utilized computer-assisted intra-operative CT-based image guidance and continuous EMG monitoring to guide percutaneous pedicle screw placement were analysed for the rates of malposition of the pedicle screws. Pedicle screw malposition was defined as having occurred if the screw trajectory was adjusted intraoperatively due to positive EMG responses, or due to breach of the pedicle cortex by more than 2mm on intraoperative CT imaging performed at the end of the instrumentation procedure. Further analysis of the data was undertaken to determine if the rates of malposition changed with the surgeon's experience with the technique.ResultsSix hundred and twenty-seven pedicle screws were placed in one hundred and fifty patients. The overall rate of intraoperative malposition and subsequent adjustment of pedicle screw placement was 3.8% (24 of 627 screws). Screw malposition was detected by intraoperative CT imaging. Warning of potential screw misplacement was provided by use of the EMG monitoring. With increased experience with the technique, rates of intraoperative pedicle screw malposition were found to decrease from 5.1% of screws in the first fifty patients, to 2.0% in the last 50 patients. Only one screw was suboptimally placed at the end of surgery, which did not result in a neurological deficit.ConclusionThe use of CT-based computer-assisted navigation in combination with continuous EMG monitoring during percutaneous transpedicular screw placement results in very low rates of malposition and neural injury that compare favourably with previously reported rates. Pedicle screw placement accuracy continues to improve as the surgeon becomes more experienced with the technique.

Study DesignRetrospective case series with prospective arm.PurposeTo assess the safety and accuracy of percutaneous lumbosacral pedicle screw placement (PLPSP) in the lumbosacral spine using intraoperative dual-planar fluoroscopy (DPF).Overview of LiteratureThere are several techniques available for achieving consistent, safe, and accurate results with PLPSP. There is a paucity of literature describing the beneficial operative, economic, and clinical outcomes of DPF, the most readily accessible image guidance system.MethodsFrom 2004 to 2014, 451 consecutive patients underwent PLPSP using DPF, for a total of 2,345 screw placement. The results of prospectively obtained postoperative computed tomography (CT) examinations of an additional 41 consecutive patients were compared with the results of 104 CT examinations obtained postoperatively due to clinical symptomatology; these results were interpreted by three reviewers. The rates of revision indicated by misplaced screws with consistent clinical symptomatology were compared between groups. Pedicle screw placement was graded according to 2-mm increments in medial pedicle wall breach and measurement of screw axis placement.ResultsSeven of the 2,345 pedicle screws placed percutaneously with the use of the dual-planar fluoroscopic technique required revision because of a symptomatic misplaced screw, for a screw revision rate of 0.3%. There were no statistically significant demographic differences between patients who had screws revised and those who did not. All screws registered greater than 10 mA on electromyographic stimulation. In the 41 prospectively obtained CT examinations, one out of 141 screws (0.7%) was revised due to pedicle wall breach; whereas among the 104 patients with 352 screws, three screws were revised (0.9%).ConclusionsDPF is an extremely accurate, safe, and reproducible technique for placement of percutaneous pedicle screws and is a readily available and cost-effective alternative to CT-guided pedicle screw placement techniques. Postoperative CT evaluation is not necessary with PLPSP unless the patient is symptomatic. Acceptable electromyographic thresholds may need to be reevaluated.

True accuracy of percutaneous pedicle screw placement in thoracic and lumbar spinal fixation with a CT-based navigation system: Intraoperative and postoperative assessment of 763 percutaneous pedicle screws

Percutaneous pedicle screw placement under single dimensional fluoroscopy with a designed pedicle finder—a technical note and case series

Minimally invasive pedicle screw fixation

20 Tips to Avoid and Handle Problems in the Placement of Percutaneous Pedicle Screws

We retrospectively evaluated 488 percutaneous pedicle screws in 110 consecutive patients that had undergone minimally invasive transforaminal lumbar interbody fusion (MITLIF) to determine the incidence of pedicle screw misplacement and its relevant risk factors. Screw placements were classified based on postoperative computed tomographic findings as "correct", "cortical encroachment" or as "frank penetration". Age, gender, body mass index, bone mineral density, diagnosis, operation time, estimated blood loss (EBL), level of fusion, surgeon's position, spinal alignment, quality/quantity of multifidus muscle, and depth to screw entry point were considered to be demographic and anatomical variables capable of affecting pedicle screw placement. Pedicle dimensions, facet joint arthritis, screw location (ipsilateral or contralateral), screw length, screw diameter, and screw trajectory angle were regarded as screw-related variables. Logistic regression analysis was conducted to examine relations between these variables and the correctness of screw placement. The incidence of cortical encroachment was 12.5% (61 screws), and frank penetration was found for 54 (11.1%) screws. Two patients (0.4%) with medial penetration underwent revision for unbearable radicular pain and foot drop, respectively. The odds ratios of significant risk factors for pedicle screw misplacement were 3.373 (95% CI 1.095-10.391) for obesity, 1.141 (95% CI 1.024-1.271) for pedicle convergent angle, 1.013 (95% CI 1.006-1.065) for EBL >400 cc, and 1.003 (95% CI 1.000-1.006) for cross-sectional area of multifidus muscle. Although percutaneous insertion of pedicle screws was performed safely during MITLIF, several risk factors should be considered to improve placement accuracy.

Introduction: Standard techniques for lumbar pedicle screw and rod fixation involve open exposure and extensive muscle dissection. Percutaneous pedicle screw system minimises the morbidity associated with traditional open approaches without compromising the quality of spinal fixation. A preliminary experience with this device has been encouraging. The purpose of this study was to demonstrate operative techniques and experiences with percutaneous lumbar pedicle screw and rod insertion for internal fixation of the lumbar spine without use of Zig. Methods: It was hospital based retrospective interventional study done at the department of Orthopaedics, B.P. Koirala Institute of Health Sciences, Dharan, Nepal over a period of 2 and half years. The study enrolled 30 patients aged 18-55 years who had presented with traumatic fracture of thoracic and lumbar spine. All thirty patients underwent percutaneous pedicle screw and rod fixation and successful percutaneous single/two level fusions. The follow up period ranged from 6 to 24 months. Results: The study comprised of 25 males and 5 females. Average patient’s age was 36.5 years (range 18-55 years). The common mode of injury was fall from height, road traffic accident, physical assault followed by sports related injury. All patients were having unstable spine fracture without neurological deficit. Operation time, loss of blood, post operative pain was less in percutaneous method. Post operative rehabilitation was easier. Spinal fusion was achieved in all patients in 6 months to 1 year time. There was no post-operative neurological deficit, infection, implant failure. Conclusion: Our early experience suggests that Minimally invasive approaches for performing lumbar fusion, is able to achieve the same clinical results as conventional open procedures. DOI: http://dx.doi.org/10.3126/noaj.v3i1.9322 Nepal Orthopedic Association Journal 2013 Vol.3(1): 23-27

ObjectiveTo evaluate the accuracy of percutaneous pedicle screw (PPS) placement aided by a new drill guide template.MethodsThe patients were divided into guide template group and conventional perspective group. In the conventional perspective group, the screws were placed by hand under fluoroscopy. In the guide template group, the screw placement was aided by a new drill guide template, and the drill guide template is designed according to the patient's ideal pedicle screw, but not based on skin morphology. The accuracy was evaluated by comparing the following parameters between the two groups: pedicle breach level, inclination angle deviation between the left and right screws, sagittal angle deviation between the left and right screws, and position deviation of the left and right screw entry points. The consistency of the postoperative screw angle and the corresponding guide template inclination angle was compared in the guide template group. The operative time, blood loss, and radiation times were compared between the groups.ResultsA total of 146 patients (876 screws) were enrolled in our study including 79 (474 screws) in the guide template group and 67 (402 screws) in the conventional perspective group. The pedicle breach level in the guide template group (22/474) was significantly lower than that in the conventional perspective group (47/402) (P < 0.05). The position and direction deviations of the left and right screws in the guide template group (2.06 ± 1.02 mm, 1.23 ± 1.25 mm, 1.83° ± 1.49°) were significantly less than those in the conventional perspective group (5.33 ± 2.99 mm, 4.32 ± 3.25 mm, 2.87° ± 1.56°). The operation time, blood loss, and radiation times were significantly lower in the guide template group (80.49 ± 9.14 min, 50.42 ± 8.9 mL, 11.02 ± 2.44) than those in the conventional perspective group (108.1 ± 21.18 min, 71.7 ± 17.09 mL, 23.53 ± 4.54). There were no significant differences between the postoperative screw angle and the corresponding guide template angle in the guide template group.ConclusionPPS placement aided by a new drill guide template yielded higher screw accuracy and less operative time, blood loss, and radiation exposure than traditional screw placement.

Since introduction of the pedicle screw-rod system, short-segment pedicle screw fixation has been widely adopted for thoracolumbar burst fractures (TLBF). Recently, the percutaneous pedicle screw fixation (PPSF) systems have been introduced in spinal surgery; and it has become a popularly used method for the treatment of degenerative spinal disease. However, there are few clinical reports concerning the efficacy of PPSF without fusion in treatment of TLBF. The purpose of this study was to determine the efficacy and safety of short-segment PPSF without fusion in comparison to open short-segment pedicle screw fixation with bony fusion in treatment of TLBF. This study included 59 patients, who underwent either percutaneous (n = 32) or open (n = 27) short-segment pedicle screw fixation for stabilization of TLBF between December 2003 and October 2009. Radiographs were obtained before surgery, immediately after surgery, and at the final follow-up for assessment of the restoration of the spinal column. For radiologic parameters, Cobb angle, vertebral wedge angle, and vertebral body compression ratio were assessed on a lateral thoracolumbar radiograph. For patient's pain and functional assessment, the visual analogue scale (VAS), the Frankel grading system, and Low Back Outcome Score (LBOS) were measured. Operation time, and the amount of intraoperative bleeding loss were also evaluated. In both groups, regional kyphosis (Cobb angle) showed significant improvement immediately after surgery, which was maintained until the last follow up, compared with preoperative regional kyphosis. Postoperative correction loss showed no significant difference between the two groups at the final follow-up. In the percutaneous surgery group, there were significant declines of intraoperative blood loss, and operation time compared with the open surgery group. Clinical results showed that the percutaneous surgery group had a lower VAS score and a better LBOS at three months and six months after surgery; however, the outcomes were similar in the last follow-up. Both open and percutaneous short-segment pedicle fixation were safe and effective for treatment of TLBF. Although both groups showed favorable clinical and radiologic outcomes at the final follow-up, PPSF without bone graft provided earlier pain relief and functional improvement, compared with open TPSF with posterolateral bony fusion. Despite several shortcomings in this study, the result suggests that ongoing use of PPSF is recommended for the treatment of TLBF.