Facet Screw Placement Research Articles

Innovative 3D Navigation Module for Precise Unilateral Pedicle Screw Combined with Contralateral Translaminar Facet Screw Placement in Lumbar Spine Surgery.

The incidence of degenerative diseases of the lumbar spine has increased in recent years. Unilateral pedicle screw combined with contralateral translaminar facet screw fixation offers the advantages of less trauma, better stability, and fewer complications. However, the surgical difficulty and suboptimal pinning accuracy of translaminar facet screw placement in clinical practice limit its use. Therefore, in this study, we designed a novel suspended 3D-printed navigation module to facilitate fast and accurate intraoperative screw placement. The aim of this study is to investigate the digital design, precise implementation, and evaluation methods for placing unilateral pedicle screws in the lumbar spine combined with translaminar facet screw placement using a new suspended 3D navigation module. This retrospective study included 46 patients with single-level lumbar lesions who underwent spine surgery at the Affiliated Hospital of Putian University between June 2022 and December 2023. The suspended navigation module was designed digitally. Preoperative screw placement was simulated using 3D printed models, followed by an intraoperative accurate screw placement facilitated by the navigation module and a postoperative evaluation of the accuracy of screw placement. The absolute difference in three-dimensional coordinates of the inlet and outlet points of the preoperative design and the postoperative screw-nail channel served as the precision index. In a study involving 46 patients, surgery was successful with 92 pedicle screws and 46 translaminar facet screws placed without any penetration of the cortex. The difference in coordinates before and after screw insertion was minimal, with entry points varying between 1.21 to 1.36 mm and exit points between 1.97 to 2.46 mm. When screw accuracy met certain thresholds, there was no significant difference between preoperative design and postoperative coordinates, indicating precise replication of the surgical plan. The new suspended 3D navigation module enables the precise placement of unilateral pedicle screws in the lumbar spine combined with translaminar pedicle screws for precise surgery.

Translaminar facet joint screw insertion with a rapid prototyping guide template: a cadaver study

It is technically demanding and requires rich experience to insert the translaminar facet screw(TFS) via the paramedian mini-incision approach. It seems that it is easy to place the TFS using computer-assisted design and rapid prototyping(RP) techniques. However, the accuracy and safety of these techniques is still unknown. The aim of this study is to assess the accuracy and safety of translaminar facet screw placement in multilevel unilateral transforaminal lumbar interbody fusion using a rapid prototyping drill guide template system. A patient-matched rapid prototyping translaminar facet screw guide was examined in fourteen cadaveric lumbar spine specimens. A three-dimensional (3D) preoperative screw trajectory was constructed using spinal computed tomography scans, from which individualized guides were developed for the placement of translaminar facet screws. Following bone tunnel establishment, the 3D positioning of the entry point and trajectory of the screws was compared to the preoperative plan as found in the Mimics software.Among 60 trajectories eligible for assessment, no cases of clinically significant laminar perforation were found. The mean deviation between the planned and the actual starting points on spinous process was 1.22 mm. The mean tail and submergence angle deviation was found to be 0.68°and 1.46°, respectively. Among all the deviations, none were found to have any statistical significance. These results indicate that translaminar facet screw placement using the guide system is both accurate and safe.

A Comparative Biomechanical Analysis of Stand Alone Versus Facet Screw and Pedicle Screw Augmented Lateral Interbody Arthrodesis: An In Vitro Human Cadaveric Model.

Cadaveric biomechanical study. To investigate the kinematic response of a stand-alone lateral lumbar interbody cage compared with supplemental posterior fixation with either facet or pedicle screws after lateral discectomy. Lateral interbody fusion is a promising minimally invasive fixation technique for lumbar interbody arthrodesis. The biomechanical stability of stand-alone cage placement compared with supplemental posterior fixation with either facet or bilateral pedicle screws remains unclear. A 6-degree of freedom spine simulator was used to test flexibility in 7 human cadaveric specimens. Flexion-extension, lateral-bending, and axial-rotation were tested in the intact condition, followed by destabilization through a lateral discectomy at L2-L3 and L4-L5. Specimens were then reconstructed at both operative segments in the following sequence: (1) lateral interbody cage placement; (2) either Discovery facet screws or the Viper F2 system using a transfacet-pedicular trajectory randomized to L2-L3 or L4-L5; and (3) removal of facet screw fixation followed by placement of bilateral pedicle screw instrumentation. Acute range of motion (ROM) was quantified and analyzed. All 4 reconstruction groups, including stand-alone interbody cage placement, bilateral Discovery facet screws, the Viper F2 system, and bilateral pedicle screw-rod stabilization, resulted in a significant decrease in acute ROM in all loading modes tested (P<0.05). There were no significant differences observed between the 4 instrumentation groups (P>0.05). Although not statistically significant, the Viper F2 system resulted in greatest reduction of acute ROM in both flexion-extension and axial rotation versus all other treatments (P>0.05). Stand-alone interbody cage placement results in a significant reduction in acute ROM at the operative segment in the absence of posterior supplemental fixation. If added fixation is desired, facet screw placement, including the Viper F2 facet screw system using an integrated compression washer and transfacet-pedicular trajectory, provides similar acute stability to the spinal segment compared with traditional bilateral pedicle screw fixation in the setting of lateral interbody cage deployment.

Clinical and Computed Tomographic Evaluation of Safety and Efficacy of Facet Screw Fixation in the Subaxial Cervical Spine

A retrospective study comparing screw positioning and associated complications between 2 different facet screw placement methods. To review the anatomic location, clinical safety, efficacy, and limitations of 2 facet screw placement techniques. Facet screw fixation in the subaxial cervical spine penetrates 4 cortical layers and affords better stability than lateral mass screws. Takayasu and colleagues recommended placing screws in the sagittal plane. We modified the trajectory to direct the screws laterally from the sagittal plane to place the root at less risk and improve fixation by increasing the excursion of the screws into bone. No clinical reports exist describing the quadricortical facet screw placed in a lateral direction. A total of 95 screws were used in 18 consecutive patients who underwent posterior cervical stabilization for various spinal disorders: 34 screws used sagittal plane screw placement and 61 used our technique. Screw-related complications were reviewed. Screw trajectories and screw tip positions related to the ventral cortical margin and vertebral artery were evaluated using postoperative 3-dimensional computed tomograms taken within 6 months after surgery. Instrumentation failures were evaluated from postoperative 3-dimensional computed tomograms taken 2 years after surgery. There was 1 complication, nerve root irritation due to screw malposition. Postoperative computed tomographic images revealed that drilling was 30 degrees lateral from the sagittal plane in our method. Fourth cortex penetration failed in 29% of the screws placed in the sagittal plane and in 5% by our method. Screw loosening was significantly increased using screws placed in the sagittal plane (24% vs. 2%). Quadricortical facet screw placement aimed at the juncture between the transverse process and the facet is practicable. Screw loosening was significantly reduced using this lateral screw direction. One of the disadvantages of this technique is that extensive cranial exposure is required to align the instruments in the proper sagittal trajectory.

Joint Kinematics of Surgeons during Lumbar Pedicle Screw Placement

Introduction Robotic spine surgery has been developed to improve spine surgery, especially the placement of pedicle screws recently. There have been no basic studies regarding the changes in joint angles and kinematics of surgeons during pedicle screw fixation. Understanding kinematics and joint movements of the surgeon during the placement of pedicle screws is essential to create an effective robot suitable for spinal surgery. The objective of this study is to assess the joint kinematics of the surgeon during the insertion of lumbar pedicle screws. Materials and Methods This is a cross-sectional study. We enrolled 18 experienced spine surgeons in this study, who each performed lumbar pedicle screw placement using a spine surgery simulator at the spinal level L3/4. To assess the movements of the surgeons, we used an optoelectronic motion analysis system with 16 cameras. A total of 20 markers were placed from the cervical spine to the pelvis (12 markers; C2, C4, C7, T6, L1, L3, PSIS x 2, ASIS x 2, Sacrum × 2), on both shoulders (2 markers; acromion), the right elbow (1 marker; olecranon), the right wrist (2 markers; ulna and radius styloid process), and the screw driver (3 markers; proximal handle × 1 and distal handle × 2). Using 3-dimentional motion images, distance changes in 5 joints (αB, body; αS, shoulder; αE, elbow; αW, wrist; and αI, instrument), and angle changes in 6 joints (αB, body; αS, shoulder; αE, elbow; αW, wrist; αI, instrument; and αP, pedicle) regarding X-, Y-, and Z-axes were calculated during pedicle screw placement. The distance and angle changes were measured at 8 setting points (L3/4 x Right/Left x Start/End) during pedicle screw placement and compared between joints. Results Whole joint distances and angles differed significantly according to setting points during pedicle screw placement. Fluctuations in distance increased gradually from the proximal joint (αB) to distal joint (αI; instrument) and the largest change was noted along the X-axis. Angle fluctuations were largest at the distal point (αP, pedicle) but did not gradually increase and the αE (elbow) showed the second largest fluctuation. Changes along the X-axis change were larger than those of the Y- and Z-axes. Conclusion The distances moved by whole joints gradually increased from proximal portions of the body to the hand, but in terms of angle changes, the elbow joint was the most dynamic during lumbar pedicle screw placement. Whole joints of surgeons carry out harmonic role during lumbar pedicle screw placement. Disclosure of Interest J. Y. Park: Conflict with Technology Innovation Program (10040097) funded by the Ministry of Trade, Industry and Energy, Republic of Korea (MOTIE, Korea) S. U. Kuh: None declared Y. E. Cho: Conflict with Technology Innovation Program (10040097) funded by the Ministry of Trade, Industry and Energy, Republic of Korea (MOTIE, Korea) References Kosmopoulos V, Schizas C. Pedicle screw placement accuracy: a meta-analysis. Spine 2007;32(3):E111-E120 Marcus HJ, Cundy TP, Nandi D, Yang GZ, Darzi A. Robot-assisted and fluoroscopy-guided pedicle screw placement: a systematic review. Eur Spine J 2014;23(2):291–297 Lieberman IH, Togawa D, Kayanja MM, et al. Bone-mounted miniature robotic guidance for pedicle screw and translaminar facet screw placement: Part I—Technical development and a test case result. Neurosurgery 2006;59(3):641-650, discussion 641–650 Devito DP, Kaplan L, Dietl R, et al. Clinical acceptance and accuracy assessment of spinal implants guided with SpineAssist surgical robot: retrospective study. Spine 2010;35(24):2109–2115 Kantelhardt SR, Martinez R, Baerwinkel S, Burger R, Giese A, Rohde V. 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Kinetic analysis of anterior cervical discectomy and fusion supplemented with transarticular facet screws

OBJECT The clinical success rates of anterior cervical discectomy and fusion (ACDF) procedures are substantially reduced as more cervical levels are included in the fusion procedure. One method that has been proposed as an adjunctive technique for multilevel ACDF is the placement of screws across the facet joints ("transfacet screws"). However, the biomechanical stability imparted by transfacet screw placement (either unilaterally or bilaterally) has not been reported. Therefore, the purpose of this study was to determine the acute stability conferred by implementation of unilateral and bilateral transfacet screws to an ACDF construct. METHODS Eight C2-T1 fresh-frozen human cadaveric spines (3 female and 5 male; mean age 50 years) were tested. Three different instrumentation variants were performed on cadaveric cervical spines across C4-7: 1) ACDF with an intervertebral spacer and standard plate/screw instrumentation; 2) ACDF with an intervertebral spacer and standard plate/screw instrumentation with unilateral facet screw placement; and 3) ACDF with an intervertebral spacer and standard plate/screw instrumentation with bilateral facet screw placement. Kinetic ranges of motion in flexion-extension, lateral bending, and axial rotation at 1.5 Nm were captured after each of these procedures and were statistically analyzed for significance. RESULTS All 3 fixation scenarios produced statistically significant reductions (p < 0.05) in all 3 bending planes compared with the intact condition. The addition of a unilateral facet screw to the ACDF construct produced significant reductions at the C4-5 and C6-7 levels in lateral bending and axial rotation but not in flexion-extension motion. Bilateral facet screw fixation did not produce any statistically significant decreases in flexion-extension motion compared with unilateral facet screw fixation. However, in lateral bending, significant reductions at the C4-5 and C5-6 levels were observed with the addition of a second facet screw. The untreated, adjacent levels (C2-3, C3-4, and C7-1) did not demonstrate significant differences in range of motion. CONCLUSIONS The data demonstrated that adjunctive unilateral facet screw fixation to an ACDF construct provides significant gains in stability and should be considered a potential option for increasing the likelihood for obtaining a successful arthrodesis for multilevel ACDF procedures.

Computed tomography–based determination of a safe trajectory for placement of transarticular facet screws in the subaxial cervical spine

Placement of transarticular facet screws is one option for stabilization of the subaxial cervical spine. Small clinical series and biomechanical data support their role as a substitute for other posterior stabilization techniques; however, the application of transarticular facet screws in the subaxial cervical spine has not been widely adopted, possibly because of surgeon unfamiliarity with the trajectory. In this study, the authors' objective is to define insertion points and angles of safe trajectory for transarticular facet screw placement in the subaxial cervical spine. Thirty fine-cut CT scans of cervical spines were reconstructed in the multiplanar mode and evaluated for safe transarticular screw placement in the subaxial cervical spine (C2-3, C3-4, C4-5, C5-6, C6-7). As in placement of lateral mass screws, the vertebral artery and exiting nerve root were bypassed posterolaterally. The entry point was set 1 mm medial and 1 mm caudal to the center of the lateral mass. From this entry point, the sagittal angulation was set to traverse the facet joint plane approximately perpendicularly. For the axial angulation, the exit point was set posterolaterally to the transverse process. After ideal insertion angles and screw lengths were identified, the trajectory was simulated on CT scans of 20 different cervical spines to confirm safe screw placement. The mean optimal mediolateral insertion angles (± SD) were as follows: 23° ± 5° at C2-3; 24° ± 4° at C3-4; 25° ± 5° at C4-5; 25° ± 4° at C5-6; and 33° ± 6° at C6-7. The mean sagittal insertion angles measured to the sagittal projection of the facet joint space were as follows: 77° ± 10° at C2-3; 77° ± 10° at C3-4; 80° ± 11° at C4-5; 81°± 8° at C5-6; and 100° ± 11° at C6-7. The mean trajectory lengths were 15 ± 2 mm at C2-3; 14 ± 1 mm at C3-4; 15 ± 1 mm at C4-5; 16 ± 2 mm at C5-6; and 23 ± 4 mm at C6-7. Simulation of these insertion angles on 20 different cervical spine CTs yielded a safe trajectory in 85%-95% of spines for C2-3, C3-4, C4-5, C5-6, and C6-7. The calculated optimal insertion angles and lengths for each level may guide the safe placement of subaxial cervical transfacet screws.

Ipsilateral pedicle screw placement with contralateral percutaneous facet screws: Early results with an alternative in lumbar arthrodesis

Transforaminal lumbar interbody fusion (TLIF) is a widely used method of surgical treatment for a variety of lumbar spinal disorders. Bilateral transpedicular instrumentation is routinely used in conjunction with an interbody graft to provide additional stability. In this technical note, we describe our fusion construct using ipsilateral pedicle screw placement on the side of TLIF and contralateral facet screw placement. We performed this construct at six levels in four patients. Suggested advantages include: low morbidity, small incision and lower cost. Outcomes parameters included radiographic evidence of solid union at four months and improvement in Oswestry Disability Index. A mean improvement from a preoperative score of 73 to 26 after surgery was observed at one-year follow-up. There were no instrument-related complications. In conclusion, this hybrid screw system minimizes contralateral dissection and is an attractive alternative to standard bilateral pedicle screw fi xation.

Bone-mounted Miniature Robotic Guidance for Pedicle Screw and Translaminar Facet Screw Placement

To introduce a new miniature robot (SpineAssist; MAZOR Surgical Technologies, Caesarea, Israel) that has been developed and tested as a surgical assistant for accurate percutaneous placement of pedicle screws and translaminar facet screws. Virtual projections in three planes-axial, lateral, and anteroposterior-are reconstructed for each vertebra from a preoperative computed tomographic (CT) scan. On a specially designed graphic user interface with proprietary software, the surgeon plans the trajectory of the screws. Intraoperative fluoroscopic x-rays with targeting devices are then matched with the CT-based virtual images, as well as the surgeon's plan. A clamp is attached to the spinous process or a minimally invasive frame (Hover-T frame; MAZOR Surgical Technologies) is mounted to the iliac crest and one spinous process. The miniature robot is then attached to the clamp and/or frame. On the basis of combined CT scan and fluoroscopic data, the robot aligns itself to the desired entry point and trajectory, as dictated by the surgeon's preoperative plan. A test case in a cadaver lumbar spine was performed in which four screws and two rods were inserted, using a minimally invasive technique, combining the SpineAssist system and Hover-T frame in conjunction with the PathFinder system (Spinal Concept Inc., Austin, TX). The discrepancy between the planned and actual screw trajectories was measured by means of postprocedural CT scan. Overall, the four screws were implanted with an average deviation of 1.02 +/- 0.56 mm (range, 0-1.5 mm) from the surgeon's plan. These preliminary results confirm the system's accuracy and support its use in minimally invasive spine surgery applications.

Less invasive posterior fixation method following transforaminal lumbar interbody fusion: a biomechanical analysis

Background context Current surgical trends increasingly emphasize the minimization of surgical exposure and tissue morbidity. Previous research questioned the ability of unilateral pedicle screw instrumentation to adequately stabilize posterior fusion constructs. No study to date has addressed the effects of reduced posterior instrumentation mass on interbody construct techniques. Unilateral surgical exposure for transforaminal lumbar interbody fusion (TLIF) allows ipsilateral pedicle screw placement. Theoretically, percutanous contralateral facet screw placement could provide supplemental construct support without additional surgical exposure. Purpose Identify the biomechanical effects of reduced spinal fusion instrumentation mass on interbody construct stability. Study design An in vitro biomechanical study using human lumbar spines comparing stability of TLIF constructs augmented by: (1) bilateral pedicle screw fixation, (2) unilateral pedicle screw fixation, or (3) a novel unilateral pedicle screw fixation supplemented with contralateral facet screw construct. Methods Seven fresh frozen human cadaveric specimens were tested in random construct order in flexion/extension, lateral bending, and axial rotation using ±5.0 Nm torques and 50 N axial compressive loads. Analysis of torque rotation curves determined construct stability. Using paired statistical methods, comparison of construct stiffness and total range of motion within each specimen were performed using the Wilcoxon signed ranks test with a Holm-Sidák multiple comparison procedure (α = 0.05). Results In flexion/extension, lateral bending, and axial rotation, there were no measurable differences in either stiffness or range of motion between the standard bilateral pedicle screw and the novel construct after TLIF. After TLIF, the unilateral pedicle screw construct provided only half of the improvement in stiffness compared with bilateral or novel constructs and allows for significant off-axis rotational motions, which could be detrimental to stability and the promotion for fusion. Conclusions All tested TLIF constructs with posterior instrumentation decreased segmental range of motion and increased segmental stiffness. While placing unilateral posterior instrumentation decreases overall implant bulk and dissection, it allows for signficantly increased segmental range of motion, less stiffness, and produces off-axis movement. The technique of contralateral facet screw placement provides the surgical advantages of unilateral pedicle screw placement with stability comparable to TLIF with bilateral pedicle screws.