Accuracy of the freehand technique for 3 fixation methods in the C-2 vertebrae

Object Intraoperative imaging often does not provide adequate visualization to ensure safe placement of screws. Therefore, the authors investigated the accuracy of a freehand technique for placement of pars, pedicle, and intralaminar screws in C-2. Methods Sixteen cadaveric specimens were instrumented freehand by 2 experienced cervical spine surgeons with either a pars or pedicle screw, and bilateral intralaminar screws. The technique was based on anatomical starting points and published screw trajectories. A pedicle finder was used to establish the trajectory, followed by tapping, palpation, and screw placement. After placement of all screws (16 pars screws, 16 pedicle screws, and 32 intralaminar screws), the C-2 segments were disarticulated, radiographed in anteroposterior, lateral, and axial planes, and meticulously inspected by another spine surgeon to determine the nature and presence of any defects. Results A total of 64 screws were evaluated in this study. Pars screws exhibited 2 critical defects (1 in the foramen transversarium and 1 in the C2–3 facet) and an insignificant dorsal cortex breech, for an overall accuracy rate of 81.3%. Pedicle screws demonstrated only 1 insignificant violation (inferior facet/medial cortex intrusion of 1 mm) with an accuracy rate of 93.8%, and intralaminar screws demonstrated 3 insignificant violations (2 in the ventral canal, 1 in the caudad lamina breech) for an accuracy rate of 90.6%. Pars screws had significantly more critical violations than intralaminar screws (p = 0.041). Conclusions Instrumentation of the C-2 vertebrae using the freehand technique for insertion of pedicle and intralaminar screws showed a high success rate with no critical violations. Pars screw insertion was not as reliable, with 2 critical violations from a total of 16 placements. The freehand technique appears to be a safe and reliable method for insertion of C-2 pedicle and intralaminar screws.

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Accuracy of robot-guided versus freehand fluoroscopy-assisted pedicle screw insertion in thoracolumbar spinal surgery

Neurosurgical FOCUS ◽

10.3171/2017.3.focus179 ◽

2017 ◽

Vol 42 (5) ◽

pp. E14 ◽

Cited By ~ 51

Author(s):

Granit Molliqaj ◽

Bawarjan Schatlo ◽

Awad Alaid ◽

Volodymyr Solomiichuk ◽

Veit Rohde ◽

...

Keyword(s):

Pedicle Screw ◽

Spinal Instrumentation ◽

Pedicle Screws ◽

Screw Placement ◽

Robotic Assistance ◽

Anatomical Landmarks ◽

Pedicle Screw Placement ◽

Robot Assisted ◽

Screw Insertion ◽

Freehand Technique

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.

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Transpedicular Screw Placement Accuracy Using the O-Arm Versus Freehand Technique at a Single Institution

Global Spine Journal ◽

10.1177/2192568220956979 ◽

2020 ◽

pp. 219256822095697

Author(s):

Benjamin D. Crawford ◽

Corbyn M. Nchako ◽

Kelsey A. Rebehn ◽

Heidi Israel ◽

Howard M. Place

Keyword(s):

Pedicle Screw ◽

Intraoperative Imaging ◽

Pedicle Screws ◽

Screw Placement ◽

Spinal Level ◽

Imaging Tool ◽

Freehand Technique ◽

Transpedicular Screw ◽

Significant Difference ◽

Placement Accuracy

Study Design: Retrospective cohort. Objective: The objective of this study was to assess the effectiveness of the O-arm as an intraoperative imaging tool by comparing accuracy of pedicle screw placement to freehand technique. Methods: The study comprised a total of 1161 screws placed within the cervical (n = 187) thoracic (n = 657), or lumbar (n = 317) spinal level. A pedicle breach was determined by any measurable displacement of the screw outside of the pedicle cortex in any plane on postoperative images. Each pedicle screw was subsequently classified by its placement relative to the targeted pedicle. Statistical analysis was then performed to determine the frequency and type of pedicle screw mispositioning that occurred using the O-arm versus freehand technique. Results: A total of 155 cases (O-arm 84, freehand 71) involved the placement of 454 pedicle screws in the O-arm group and 707 pedicle screws in the freehand group. A pedicle breach occurred in 89 (12.6%) screws in the freehand group and 55 (12.1%) in the O-arm group ( P = .811). Spinal level operated upon did not influence pedicle screw accuracy between groups ( P > .05). Three screws required revision surgery between the 2 groups (O-arm 1, freehand 2, P > .05). The most frequent breach type was a lateral pedicle breach (O-arm 22/454, 4.8%; freehand 54/707, 7.6%), without a significant difference between groups ( P > .05). Conclusions: The use of the O-arm coupled with navigation does not assure improved transpedicular screw placement accuracy when compared with the freehand technique.

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Power-assisted pedicle screws placement: Is it as safe and as effective as manual technique? Narrative review of the literature and our technique

MUSCULOSKELETAL SURGERY ◽

10.1007/s12306-021-00714-x ◽

2021 ◽

Author(s):

C. Faldini ◽

G. Viroli ◽

M. Fiore ◽

F. Barile ◽

M. Manzetti ◽

...

Keyword(s):

Recent Trend ◽

Pedicle Screws ◽

Review Of The Literature ◽

Pull Out ◽

Freehand Technique ◽

Speed Up ◽

Potential Risks ◽

Power Tools ◽

Spine Surgeon ◽

Pull Out Strength

AbstractPedicle screws are the gold standard in spine surgery, allowing a solid tricolumnar fixation which is unmatched by hooks and wires. The freehand technique is the most widely adopted for pedicle screws placing. While freehand technique has been classically performed with manual tools, there has been a recent trend toward the use of power tools. The aim of this review is to summarize and expose potential risks and advantages of power pedicle screws placing. The literature showed that the use of power tools offers an acceptable safety profile, comparable to manual technique. With an adequate training, the power technique may speed up the screw placing, reduce the fluoroscopy time and the physical stress to the spine surgeon. Regarding differences in pull-out strength between power and manual techniques, the literature is still uncertain and inconsistent, both in clinical and preclinical studies. The choice between the use of power and manual freehand pedicle screws placing is still based on the surgeon’s own preference.

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A case series of eight scoliosis patients undergone pedicle screw placement with freehand technique: study for safety and accuracy

Medical Journal of Indonesia ◽

10.13181/mji.cr.191978 ◽

2020 ◽

Vol 29 (2) ◽

pp. 222-7

Author(s):

Komang Agung Irianto ◽

Marquee Kenny Tumbelaka

Keyword(s):

Ct Scan ◽

Vertebral Body ◽

Intraoperative Imaging ◽

Case Series ◽

Deformity Correction ◽

Pedicle Screws ◽

Lateral Side ◽

Scoliosis Surgery ◽

Safety Zone ◽

Freehand Technique

BACKGROUND Pedicle screws and rods are routinely inserted in the vertebrae thoracic to lumbar in scoliosis reconstruction surgery to gain deformity correction and fusion. Intraoperative imaging is often needed to ensure accuracy, but surgical time will be longer and there will be more radiation exposure. Meanwhile, freehand technique is accepted as safe. This study was aimed to evaluate the accuracy of screw insertion in the freehand technique used in adolescent scoliosis surgery. METHODS This case series evaluated a total of 127 pedicle screws inserted using the freehand technique in 8 out of 28 adolescent scoliosis patients from 2011 to 2016 whom agreed for computed tomography (CT) scan follow-up from 2011 to 2016 in Dr. Seotomo Hospital, Surabaya. The accuracy and safety of the freehand technique were evaluated postoperatively in each patient using a CT scan. A successful screw was considered accurate if it was within the vertebral body and inside the safety zone within the limit of 2–4 mm to the medial or lateral side of the vertebral body. RESULTS Of the 127 screws inserted, 106 (83.5%) were accurately placed, and 110 (86.6%) were within the safe zone. According to the level of the spine, in the upper and middle thoracic spine, the inserted screws were accurate in 69.4% and 74.9% within the safety zone, whereas in the lower thoracic and lumbar spine, 94.0% and 95.0% within the safety zone. CONCLUSIONS The freehand technique in scoliosis reconstructive surgery performed by experienced surgeons is accurate and safe.

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Is Freehand Technique of Pedicle Screw Insertion in Thoracolumbar Spine Safe and Accurate? Assessment of 250 Screws

Journal of Neurosciences in Rural Practice ◽

10.4103/jnrp.jnrp_183_18 ◽

2019 ◽

Vol 10 (02) ◽

pp. 256-260 ◽

Cited By ~ 1

Author(s):

N. Vijayeswaran ◽

Raju Venkatesh ◽

G. Murugesan ◽

S. Balamurugan ◽

K. Indunesh ◽

...

Keyword(s):

Pedicle Screw ◽

Screw Fixation ◽

Thoracolumbar Spine ◽

Pedicle Screws ◽

Pedicle Screw Fixation ◽

Screw Insertion ◽

Freehand Technique ◽

Close Observation ◽

Screw Penetration ◽

Surgical Duration

ABSTRACT Background: Pedicle screw fixation is one of the widely used procedures for instrumentation and stabilization of the thoracic and lumbar spine. It has the advantage of stabilizing all the three columns in single approach. Various assistive techniques are available to place the pedicle screws more accurately but at the expense of increased exposure to radiation, prolonged surgical duration, and cost. Objective: The objective of this study is to determine the accuracy and safety of pedicle screw fixation in the thoracolumbar spine using freehand surgical technique. Materials and Methods: We evaluated all patients who underwent pedicle screw fixation of the thoracolumbar spine for various ailments at our institute from January 2016 to December 2017 with postoperative computed tomography scan for placement accuracy. We used Gertzbein classification to grade pedicle breaches. Screw penetration more than 4 mm was taken as critical and those less than that were classified as noncritical. Results: A total of 256 screws inserted in T1–L5 vertebrae were included from 40 consecutive patients. Six screws were excluded according to selection criteria. The mean age was 39 years. Trauma (36 patients) was the common reason for which the pedicle screw fixation was done followed by degenerative disease (2 patients) and tumour (2 patients). A total of ten pedicle screw breaches (4%) were identified in eight patients. Among these, three critical breaches (1.2%) were occurred in two patients which required revision. The remaining seven breaches were noncritical and kept under close observation and follow-up. Conclusion: Pedicle screw had become the workhorse of posterior stabilization of the spine. Based on external anatomy and landmarks alone, freehand technique for pedicle screw fixation can be performed with acceptable safety and accuracy avoiding cumulative radiation exposure and prolonged operative time.

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Cortex of the pedicle of the vertebral arch. Part I: deformation characteristics during screw insertion

Journal of Neurosurgery Spine ◽

10.3171/spi-07/09/341 ◽

2007 ◽

Vol 7 (3) ◽

pp. 341-346 ◽

Cited By ~ 1

Author(s):

İnceoğlu Serkan ◽

Cumhur Kılınçer ◽

Andrea Tami ◽

Robert F. McLain

Keyword(s):

Plastic Deformation ◽

Pedicle Screws ◽

Lateral Wall ◽

Optimal Placement ◽

Screw Placement ◽

Deformation Characteristics ◽

Pullout Strength ◽

Screw Insertion ◽

Medial Cortex ◽

Vertebral Arch

Object Elastic deformation has been proposed as a mechanism by which vertebral pedicles can maintain pullout strength when conical screws are backed out from full insertion. The response to the insertion technique may influence both the extent of deformation and the risk of acute fracture during screw placement. The aim of this study was to determine the deformation characteristics of the lumbar pedicle cortex during screw placement. Methods Lumbar pedicles with linear strain gauges attached at the lateral and medial cortices were instrumented using 7.5-mm pedicle screws with or without preconditioning by insertion and removal of 6.5-mm screws. The strains and elastic recoveries of the medial and lateral cortices were determined. Results Mean medial wall strains tended to be lower than mean lateral wall strains when the 6.5-mm and 7.5-mm screw data were pooled (p = 0.07). After the screws had been removed, 71 to 79% of the deformation at the lateral cortex and 70 to 96% of the deformation at the medial cortex recovered. When inserted first, the 7.5-mm screw caused more plastic deformation at the cortex than it did when inserted after the 6.5-mm screw. Occasional idiosyncratic strain patterns were observed. No gross fracture was observed during screw placement. Conclusions Screw insertion generated plastic deformation at the pedicle cortex even though the screw did not directly contact the cortex. The lateral and medial cortices responded differently to screw insertion. The technique of screw insertion affected the deformation behavior of the lumbar pedicles. With myriad options for screw selection and placement available, further study is needed before optimal placement parameters can be verified.

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Evaluation of a more ventral starting point for thoracic pedicle screws: higher maximal insertional arc and more medial and safer screw angulation

Journal of Neurosurgery Spine ◽

10.3171/2018.8.spine18175 ◽

2019 ◽

Vol 30 (3) ◽

pp. 337-343

Author(s):

James D. Lin ◽

Chao Wei ◽

Jamal N. Shillingford ◽

Eduardo C. Beauchamp ◽

Lee A. Tan ◽

...

Keyword(s):

Pedicle Screw ◽

3D Visualization ◽

Pedicle Screws ◽

Transverse Process ◽

Dorsal Cortex ◽

Screw Insertion ◽

Primary Surgery ◽

Starting Point ◽

Thoracic Pedicle Screws ◽

Margin For Error

OBJECTIVETo demonstrate that a more ventral starting point for thoracic pedicle screw insertion, produced by aggressively removing the dorsal transverse process bone down to the superior articular facet (SAF), results in a larger margin for error and more medial screw angulation compared to the traditional dorsal starting point (DSP). The margin for error will be quantified by the maximal insertional arc (MIA).METHODSThe study population included 10 consecutive operative patients with adult idiopathic scoliosis who underwent primary surgery. All measurements were performed using 3D visualization software by an attending spine surgeon. The screw starting points were 2 mm lateral to the midline of the SAF in the mediolateral direction and in the center of the pedicle in the cephalocaudal direction. The DSP was on the dorsal cortex. The ventral starting point (VSP) was at the depth of the SAF. Measurements included distance to the pedicle isthmus, MIA, and screw trajectories.RESULTSTen patients and 110 vertebral levels (T1–11) were measured. The patients’ average age was 41.4 years (range 18–64 years). The pedicle isthmus was largest at T1 (4.04 ± 1.09 mm), and smallest at T5 (1.05 ± 0.93 mm). The distance to the pedicle isthmus was 7.47 mm for the VSP and 11.92 mm for the DSP (p < 0.001). The MIA was 15.3° for the VSP and 10.1° for the DSP (p < 0.001). Screw angulation was 21.7° for the VSP and 16.8° for the DSP (p < 0.001).CONCLUSIONSA more ventral starting point for thoracic pedicle screws results in increased MIA and more medial screw angulation. The increased MIA represents an increased tolerance for error that should improve the safety of pedicle screw placement. More medial screw angulation allows improved triangulation of pedicle screws.

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Image-Guided Spinal Surgery and Robotics in MIS: Where Are We Now?

Neurologico Spinale Medico Chirurgico ◽

10.15562/nsmc.v1i2.80 ◽

2018 ◽

Vol 1 (2) ◽

pp. 2

Author(s):

Chiung Chyi Shen

Keyword(s):

Pedicle Screw ◽

Spinal Surgery ◽

Surgical Navigation ◽

Improve Patient Safety ◽

Intraoperative Imaging ◽

Spinal Instrumentation ◽

Pedicle Screws ◽

Computer Assisted ◽

Navigation Systems ◽

Image Guided

Use of pedicle screws is widespread in spinal surgery for degenerative, traumatic, and oncological diseases. The conventional technique is based on the recognition of anatomic landmarks, preparation and palpation of cortices of the pedicle under control of an intraoperative C-arm (iC-arm) fluoroscopy. With these conventional methods, the median pedicle screw accuracy ranges from 86.7% to 93.8%, even if perforation rates range from 21.1% to 39.8%.The development of novel intraoperative navigational techniques, commonly referred to as image-guided surgery (IGS), provide simultaneous and multiplanar views of spinal anatomy. IGS technology can increase the accuracy of spinal instrumentation procedures and improve patient safety. These systems, such as fluoroscopy-based image guidance ("virtual fluoroscopy") and computed tomography (CT)-based computer-guidance systems, have sensibly minimized risk of pedicle screw misplacement, with overall perforation rates ranging from between 14.3% and 9.3%, respectively."Virtual fluoroscopy" allows simultaneous two-dimensional (2D) guidance in multiple planes, but does not provide any axial images; quality of images is directly dependent on the resolution of the acquired fluoroscopic projections. Furthermore, computer-assisted surgical navigation systems decrease the reliance on intraoperative imaging, thus reducing the use of intraprocedure ionizing radiation. The major limitation of this technique is related to the variation of the position of the patient from the preoperative CT scan, usually obtained before surgery in a supine position, and the operative position (prone). The next technological evolution is the use of an intraoperative CT (iCT) scan, which would allow us to solve the position-dependent changes, granting a higher accuracy in the navigation system.

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Augmented reality–assisted pedicle screw insertion: a cadaveric proof-of-concept study

Journal of Neurosurgery Spine ◽

10.3171/2018.12.spine181142 ◽

2019 ◽

Vol 31 (1) ◽

pp. 139-146 ◽

Cited By ~ 11

Author(s):

Camilo A. Molina ◽

Nicholas Theodore ◽

A. Karim Ahmed ◽

Erick M. Westbroek ◽

Yigal Mirovsky ◽

...

Keyword(s):

Augmented Reality ◽

Pedicle Screw ◽

User Experience ◽

Pedicle Screws ◽

Screw Insertion ◽

Pedicle Screw Insertion ◽

Insertion Method ◽

Comparative Accuracy ◽

Placement Accuracy ◽

Surgical Field

OBJECTIVEAugmented reality (AR) is a novel technology that has the potential to increase the technical feasibility, accuracy, and safety of conventional manual and robotic computer-navigated pedicle insertion methods. Visual data are directly projected to the operator’s retina and overlaid onto the surgical field, thereby removing the requirement to shift attention to a remote display. The objective of this study was to assess the comparative accuracy of AR-assisted pedicle screw insertion in comparison to conventional pedicle screw insertion methods.METHODSFive cadaveric male torsos were instrumented bilaterally from T6 to L5 for a total of 120 inserted pedicle screws. Postprocedural CT scans were obtained, and screw insertion accuracy was graded by 2 independent neuroradiologists using both the Gertzbein scale (GS) and a combination of that scale and the Heary classification, referred to in this paper as the Heary-Gertzbein scale (HGS). Non-inferiority analysis was performed, comparing the accuracy to freehand, manual computer-navigated, and robotics-assisted computer-navigated insertion accuracy rates reported in the literature. User experience analysis was conducted via a user experience questionnaire filled out by operators after the procedures.RESULTSThe overall screw placement accuracy achieved with the AR system was 96.7% based on the HGS and 94.6% based on the GS. Insertion accuracy was non-inferior to accuracy reported for manual computer-navigated pedicle insertion based on both the GS and the HGS scores. When compared to accuracy reported for robotics-assisted computer-navigated insertion, accuracy achieved with the AR system was found to be non-inferior when assessed with the GS, but superior when assessed with the HGS. Last, accuracy results achieved with the AR system were found to be superior to results obtained with freehand insertion based on both the HGS and the GS scores. Accuracy results were not found to be inferior in any comparison. User experience analysis yielded “excellent” usability classification.CONCLUSIONSAR-assisted pedicle screw insertion is a technically feasible and accurate insertion method.

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Validation of Freehand Cervical Pedicle Screw Placement in Subaxial Spine Using the “Burcev Technique”: A Cadaveric Study

Journal of Neurosciences in Rural Practice ◽

10.1055/s-0041-1727410 ◽

2021 ◽

Author(s):

Mantu Jain ◽

Rabi N. Sahu ◽

Manisha R. Gaikwad ◽

Sashikanta Panda ◽

Amit Tirpude ◽

...

Keyword(s):

Horizontal Plane ◽

Sagittal Plane ◽

Pedicle Screws ◽

Continuous Variables ◽

Pedicle Screw Placement ◽

Cervical Pedicle Screw ◽

Freehand Technique ◽

Computed Tomography Scans ◽

Cervical Pedicle ◽

Cervical Pedicle Screws

AbstractThe present study attempted to validate the “Burcev freehand method” based on anatomical observations in Indian cadavers. The study was conducted on 32 cervical pedicle screws (CPSs) that were placed in four cadavers by the authors according to the “freehand technique,” described by Burcev et al, without the aid of fluoroscopy and the trajectory verified by computed tomography scans. The screws were designated as satisfactory, permissible, or unacceptable. Descriptive variables were represented in number and percentages, continuous variables were represented as mean ± standard deviation (SD). Of the 32 CPSs placed, 24 (75%) exhibited a satisfactory position, 1 (3%) exhibited a permissible position, and 7 (22%) exhibited an unacceptable position. Of the seven CPSs in the unacceptable group, four exhibited a lateral breach and three exhibited a medial breach, whereas the CPS in the permissible group exhibited a medial breach. The overall angle with contralateral lamina in the horizontal plane in terms of mean ± SD was 175.43 ± 2.82, 169.49, and 169.65 ± 6.46 degrees in the satisfactory, permissible, and unacceptable groups, respectively. In the sagittal plane, the screws exhibited an angle of 88.15 ± 3.56 degrees. No breach was observed superiorly or inferiorly. The “Burcev technique” is replicable with similar results in cadavers. Further studies must be conducted in a clinical setting to ensure its safety.

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