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

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OBJECTIVE

The 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.

METHODS

This 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.

RESULTS

In 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).

CONCLUSIONS

The 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.

ABBREVIATIONS BMI = body mass index.

Abstract

OBJECTIVE

The 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.

METHODS

This 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.

RESULTS

In 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).

CONCLUSIONS

The 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.

The insertion of pedicle screws remains one of the crucial steps in thoracolumbar posterior instrumentation. Improvement of techniques that can facilitate procedures and increase accuracy in screw insertion is of crucial importance because the incorrect positioning of screws is associated with complications such as neurological deficits or vascular injuries.2 Pedicle screw insertion can be challenging, especially in patients with a spinal deformity such as scoliosis and in revision surgery where the anatomical landmarks have been altered.5,16 Many important structures, such as the spinal cord, nerve root, and vessels, are in close proximity to the pedicle.19 The reported rates of complications related to pedicle screw misplacement range from 1% up to 54%.3,16,19

The robotic surgical assistance system SpineAssist (Mazor) was developed to increase the accuracy of pedicle screw trajectories.15,17 After preoperative imaging acquisition and planning of the desired screw trajectories, intraoperative registration is performed using 2 fluoroscopic images that are matched with the preoperative CT scan. The robot is mounted on a bridge that can be attached to the patient’s spine, the iliac crest, or the operating table. The guidance arm moves to provide the surgeon with the preplanned trajectory. It is therefore a semi-active robotic system. The surgeon manually performs the drilling and screw insertion using an open or percutaneous technique.

The aim of this study was to compare the accuracy of robot-guided screw insertion with fluoroscopy-guided conventional technique in thoracolumbar surgery.

Methods

After institutional review board approval was obtained, we analyzed radiological data obtained in 169 patients who had undergone posterior instrumentation for spinal instability. Surgeries were performed by 2 senior surgeons (E.T. and B.S.) at 2 centers, from 2007 to 2015. This study is an update from our database of some patients reported on in 2014, with the addition of 74 new patients operated on at 2 reference centers.13 All patients had complete imaging studies including pre- and postoperative CT scans. Inclusion criteria were thoracolumbar posterior fusion to treat trauma, tumor, or degenerative disease. In the robot cohort (98 patients, 439 screws), open or percutaneous screw insertion was performed. In the fluoroscopy cohort (71 patients, 431 screws), screws were inserted freehand using anatomical landmarks and lateral fluoroscopic guidance. Patients operated on before 2009 were included in the fluoroscopy-assisted cohort, whereas those treated since mid-2009, the period when the Mazor robot was acquired, were included in the robot-guided cohort. From there, the decision to operate using robotic assistance or conventional freehand technique was based on surgeon’s discretion and logistical reasons.

The primary outcome measure was the accuracy of screw placement evaluated on a postoperative CT scan according to the scale proposed by Gertzbein and Robbins (from Grade A to E: A, perfect intrapedicular localization; B, < 2-mm pedicle breach; C, < 4-mm pedicle breach; D, < 6-mm pedicle breach; and E, a ≥ 6-mm deviation from the pedicle cortex (Fig. 1).4 The radiological slice with the largest deviation from the pedicle was chosen for grading after analysis of axial, coronal, and sagittal views. A neuroradiologist who was blinded to the type of treatment evaluated all CT scans in both groups. Screws graded as A and B were considered to be clinically acceptable and were compared with the remaining “non-acceptable” screws using the Fisher chi-square test with a 2-sided significance level set at < 0.05.

Fig. 1.
Fig. 1.

CT scans demonstrating the Gertzbein-Robbins classification of screw positioning. The grades reflect the deviation of the screw from the “ideal” intrapedicular trajectory. Grade A is an intrapedicular screw without breach of the cortical layer of the pedicle; Grade B reflects a screw that breaches the cortical layer of the pedicle but does not exceed it laterally by > 2 mm. Grades C and D indicate a penetration of < 4 and < 6 mm, respectively. Grade E indicates a screw that does not pass through the pedicle or that, at any given point in its intended intrapedicular course, breaches the cortical layer of the pedicle in any direction by 6 mm or more. Modified with permission from Schatlo et al: J Neurosurg Spine 20:636–243, 2014.

Robot-Guided Surgical Technique

In the robot-guided group, pedicle screws were placed using robotic guidance. Three steps are necessary: preoperative planning, intraoperative registration, and robot-guided screw placement. The first step involves a preoperative analysis of the anatomy of the patient on the basis of a preoperative CT scan. Planning of screw insertion is carried out on the SpineAssist image-processing unit, including the determination of the screw entry point, the size of screws, and the trajectories planned in axial, coronal and sagittal views. Thus planning was done before the surgery on a computer, but it can also be done in the operating room on the robot console.

Intraoperatively, the patient is in the prone position and a clamp is rigidly fixed on the spinous process. This is followed by placement of 2 additional pins in the spinous process above and below. This bone mounting ensures that the robot is fixed to the patient’s vertebrae and avoids errors attributed to inaccuracy in previous trials.11

To indicate the particular location of the mounting platform on fluoroscopy, a 3D marker is attached to it. Two fluoroscopic images of the 3D marker and spine are taken in anteroposterior and oblique views. The software automatically matches the intraoperative images to the corresponding locations on the preoperative CT.

To begin the surgical procedure, the surgeon selects the target vertebra from the preoperative plan, and the robot steers toward the chosen trajectory and indicates to the surgeon the entry point and direction of pedicle screw trajectory. The surgeon checks the suggested trajectory with a fluoroscopic image. After making a stab incision through skin and fascia, the surgeon inserts the cannula further until reaching the surface of the bone; drilling is performed, and screws are inserted through a K-wire. In our first 20 cases, drill advancement was followed on lateral fluoroscopy.

Freehand Fluoroscopy-Guided Surgical Technique

In the freehand group, the patient is placed in the prone position and the spine is prepared subperiostially to expose the transverse process, facet joint, and isthmus, which are used as anatomical landmarks for the entry point for screws. The pedicle is perforated with a probe and palpator. Screws are inserted using lateral fluoroscopic guidance and a K-wire. An anteroposterior fluoroscopic image is obtained at the end of this process to ensure that the screws are sufficiently convergent and correctly placed with respect to the medial border of the pedicle.

Statistical Analysis

Group comparisons were made using Fisher’s exact with chi-square tests with a significance level of p < 0.05. Continuous variables were compared using the Mann-Whitney U-test. Binary multivariate regression was used to assess whether obesity (body mass index [BMI] > 30 kg/m2) or osteoporosis (bone density below 2.5 SDs below a reference population) affected the likelihood of a given patient to have screw misplacement. SPSS 18.0 (IBM) was used to perform the statistical analyses.

Results

Baseline Characteristics

Most baseline characteristics did not differ between the robot-guided and freehand fluoroscopy-guided groups (Table 1). The distribution between men and women in both groups was homogeneous.

TABLE 1.

Baseline characteristics

CharacteristicOverallRobot GroupFreehand Groupp Value
No. of patients*1699871
Sex*
 Female8348351.00
 Male8650361.00
Age (yrs)57.6 ± 558.3 ± 12.854.4 ± 170.33
Screws per case5.21 ± 3.234.47 ± 2.186.21 ± 2.870.03
Pathology*
 Degenerative13283 (84.7)49 (69)0.02
 Tumor115 (5.1)6 (8.5)
 Trauma2610 (10.2)16 (22.5)

Values are the number or the number (%) of patients.

Values are the mean ± SD.

Primary Outcome

We analyzed the accuracy of pedicle screw fixation in 169 consecutives patients (83 women and 86 men) in whom lumbar thoracolumbar instrumentation was placed from 2010 to 2015 (Table 1). A detailed listing of pedicle screw accuracy grades is provided in Table 2. Overall, the analysis highlighted a clear improvement of accuracy for the robot cohort compared with the freehand cohort. In the robot group, a perfect trajectory (Gertzbein-Robbins Grade A) was observed for 366 (83.4%) of the 439 screws. 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 freehand fluoroscopy-guided group, a completely intrapedicular course of Grade A was found in 76% of the screws (n = 335 of 441 screws). 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 rate of “clinically acceptable” screw positions (which corresponds to Grade A and B) was higher in the robot group than the freehand group, 93.4% and 88.9%, respectively (p = 0.005). The number of screws that exhibited a poor trajectory (Grades C, D, and E) was significantly lower in the robot group than the freehand group (29 [6.6%] of 439 screws vs 49 [11.1%] of 441 screws, respectively; p = 0.005).

TABLE 2.

Pedicle screw placement accuracy according to the Gertzbein and Robbins classification

Screw GradeNo. of Patients (%)p Value
Robot GroupFreehand Group
A366 (83.4)335 (75)0.005
B44 (10)57 (12.9)
C15 (3.4)29 (6.6)
D8 (1.8)12 (2.7)
E6 (1.4)8 (1.8)
Total439 (100)441 (100)

The rate of screw misplacement was lowest when using the robot in the lumbosacral region of the spine (5.9% in the freehand group vs 2.1% in the robot group; p < 0.001) (Table 3). However, no difference was found with respect to thoracic screws (p = 0.378).

TABLE 3.

Comparison of screw misplacement by spinal region

Spinal RegionRobot Group (%)Freehand Group (%)p Value
Total No. of ScrewsNo. of Misplaced ScrewsTotal No. of ScrewsNo. of Misplaced Screws
Thoracic606 (10)14422 (15.2)0.378
Lumbosacral3799 (2.3)29726 (8.8)<0.001
Total43915 (3.4)44148 (10.9)

Multivariate regression analysis did not confirm a potential role of either osteoporosis or BMI as predictors of screw misplacement in our cohort. In the freehand group, the odds ratio for screw misplacement in patients with BMI > 30 kg/m2 was 1.7 (95% CI 0.4–6.5; p = 0.46); the odds ratio for osteoporotic patients was 1.2 (95% CI 0.3–4.4; p = 0.78). In the robot group, the odds ratio for screw misplacement in case of obesity was 1.6 (95% CI 0.2–16.7; p = 0.71), whereas for osteoporosis it was < 0.1 (0–not applicable; p = 0.99).

Discussion

The effectiveness and the improvement of accuracy obtained by using the SpineAssist robotic system was the topic of this retrospective study, which included 169 patients. The analysis highlighted a clear improvement in accuracy when robotic guidance used to place screws was compared with the freehand fluoroscopic guidance. Effectively, in the robot group a perfect trajectory (Grade A) was observed for 366 screws (83.4%) whereas the same grade was seen for 335 screws (76%) in the freehand fluoroscopy group. Moreover, the rate of “clinically acceptable” screw positions (which correspond to A and B screws) was significantly higher in the robot group than the freehand group (93.4% and 88.9%, respectively). The total rate of misplaced thoracolumbar screws was lower in the robot group, but this difference was not statistically significant for the thoracic screws, which can be explained by a statistical bias generated by the fact that there are more screws in the freehand group at the thoracic level than in the robot group.

Improving accuracy and safety in pedicle screw insertion has led to the development of multiple new techniques such as image guidance with navigation, intraoperative imaging, and robot-assisted spine surgery. Of course, a learning curve is necessary for each new technique introduced into the market. It has been estimated that a minimum of 25 procedures is necessary for mastering the technique involved in using the first-generation Mazor robotic system.13 However, the more recent generation seems to be less demanding in terms of technique.9 For surgeons not acquainted with minimally invasive techniques, robotic surgery could facilitate its adoption. The reduction in radiation exposure is also a significant argument in favor of robotic technology in the light of rising awareness of the need to reduce radiation exposure for operating room personnel.12

A review of the literature shows screw placement rates close to those obtained in our study. A randomized controlled study published by Roser et al. showed that 99% of screws were satisfactorily placed with robotic assistance compared with 98% in the freehand group.12 In a study by a different group of authors, up to 98.3% of screws were shown to be within 2 mm of the preoperatively planned location when the SpineAssist system was used.10 In the same trend, a retrospective multicenter study, Devito et al. found a rate of 98% of clinically acceptable screw placements when using the SpineAssist robot.1 One year later, Kantelhardt et al. performed a retrospective comparison of robot-assisted and conventionally placed screws and reported accuracy rates of 94.5% and 91.4%, respectively.7 More recently, van Dijk et al. reported 97.9% accuracy in their retrospective review of 112 patients who underwent minimally invasive spine surgery involving robotic guidance.18

In contrast, the study from Ringel and colleagues found the conventional freehand technique to have superior accuracy compared with the SpineAssist robot technique, with good placement seen for 93% and 85% of screws, respectively.11 The lesser accuracy was attributed to the use of a bed-mounted frame that is not rigidly fixed to the patients’ spines. Therefore, the risk of movement of the robot arm relative to the patient may have induced a higher rate of screw misplacement. We implemented the use of spinous process fixation to avoid this inaccuracy.

Recently, the latest-generation Mazor robotic systems, the Renaissance, has been shown to be accurate and useful in thoracolumbar screw placement. For example, Hyun et al. obtained better accuracy in the robot group than the fluoroscopic open surgery group.6 Kim et al. published a randomized controlled trial of robot-assisted versus freehand pedicle screw fixation in 78 patients (37 with robot-assisted and 41 freehand surgery), and they concluded that robot-assisted pedicle screw placement was associated with fewer proximal facet joint violations and better screw trajectories, but the rate of intrapedicular accuracy was not different between the groups.8

Limitations of the Technique

This study clearly shows that the risk for pedicle screw malpositioning exists despite the use of robotic system guidance. One possible explanation of that is the so-called skiving phenomenon.5 The percutaneously inserted cannula can skive on a bony surface, such as a facet bony spur, with potential inaccuracy of the drilling procedure. Using a specific tool that is able to flatten the entry point before cannula introduction may solve this problem.

In the current and a previous study we have shown that the screw malpositioning rate was higher at the sacral level than at the lumbar level, especially in cases traditional open surgery.14 The large lever arm related to the robotic cannula (often needed for approaching the S-1 entry point) and, laterally, the soft-tissue pressure exerted on the cannula itself might explain the higher inaccuracy rate observed in sacral pedicle screw insertion. We suggest performing the percutaneous approach through a stab incision at the sacral level, even in cases of traditional open surgery. Another way is to ensure good soft-tissue retraction when inserting sacral screws, which require a more lateral entry point and a more medially directed trajectory. Finally, although the addition of the robot was helpful, it cannot replace the knowledge of the surgical anatomy held by the surgeon and the surgeon’s ability to manage unexpected intraoperative events. The last solution is to rely on the anatomical reference and to opt for insertion of the screws according to the traditional technique of freehand surgery.

Installation of the robotic clamp on spinous processes and the use of the software during surgery increase the length of surgical procedure compared with the conventional freehand technique, especially in the surgeon’s very first cases. Compared with intraoperative imaging and navigation setup, the robotic system adds little clutter to the conventional work space. The robot console takes up the space of an additional instrument table. In addition, the C-arm needs to be equipped with a fiducial array. Whether the costs of acquisition and the expenses incurred by additional sterile material make up for hypothetical clinical benefit remains to be determined in future studies.

Conclusions

Our retrospective case review found that robot-guided pedicle screw placement is a safe, useful, and potentially more accurate alternative to conventional techniques for the placement of thoracolumbar spinal instrumentation.

Disclosures

Dr. Tessitore is a consultant for Mazor Robotics.

Author Contributions

Conception and design: Molliqaj, Schatlo, Schaller, Tessitore. Acquisition of data: Molliqaj, Schatlo, Alaid, Solomiichuk, Tessitore. Analysis and interpretation of data: Molliqaj, Schatlo, Schaller, Tessitore. Drafting the article: Molliqaj, Schatlo, Tessitore. Critically revising the article: Molliqaj, Schatlo, Schaller, Tessitore. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Molliqaj. Statistical analysis: Molliqaj, Schatlo, Tessitore. Administrative/technical/material support: Molliqaj, Schatlo, Schaller, Tessitore. Study supervision: Molliqaj, Schatlo, Schaller, Tessitore.

Supplemental Information

Videos

Video Abstract. https://vimeo.com/212582499.

References

  • 1

    Devito DPKaplan LDietl RPfeiffer MHorne DSilberstein B: Clinical acceptance and accuracy assessment of spinal implants guided with SpineAssist surgical robot: retrospective study. Spine (Phila Pa 1976) 35:210921152010

  • 2

    Gaines RW Jr: The use of pedicle-screw internal fixation for the operative treatment of spinal disorders. J Bone Joint Surg Am 82-A:145814762000

  • 3

    Gautschi OPSchatlo BSchaller KTessitore E: Clinically relevant complications related to pedicle screw placement in thoracolumbar surgery and their management: a literature review of 35,630 pedicle screws. Neurosurg Focus 31(4):E82011

  • 4

    Gertzbein SDRobbins SE: Accuracy of pedicular screw placement in vivo. Spine (Phila Pa 1976) 15:11141990

  • 5

    Hu XOhnmeiss DDLieberman IH: Robotic-assisted pedicle screw placement: lessons learned from the first 102 patients. Eur Spine J 22:6616662013

  • 6

    Hyun SJKim KJJahng TAKim HJ: Minimally invasive, robotic-vs. open fluoroscopic-guided spinal instrumented fusions—a randomized, controlled trial. Spine (Phila Pa 1976) [epub ahead of print]2016

  • 7

    Kantelhardt SRMartinez RBaerwinkel SBurger RGiese ARohde V: Perioperative course and accuracy of screw positioning in conventional, open robotic-guided and percutaneous robotic-guided, pedicle screw placement. Eur Spine J 20:8608682011

  • 8

    Kim HJJung WIChang BSLee CKKang KTYeom JS: A prospective, randomized, controlled trial of robot-assisted vs freehand pedicle screw fixation in spine surgery. Int J Med Robot [epub ahead of print]2016

  • 9

    Kim HJLee SHChang BSLee CKLim TOHoo LP: Monitoring the quality of robot-assisted pedicle screw fixation in the lumbar spine by using a cumulative summation test. Spine (Phila Pa 1976) 40:87942015

  • 10

    Pechlivanis IKiriyanthan GEngelhardt MScholz MLücke SHarders A: Percutaneous placement of pedicle screws in the lumbar spine using a bone mounted miniature robotic system: first experiences and accuracy of screw placement. Spine (Phila Pa 1976) 34:3923982009

  • 11

    Ringel FStüer CReinke APreuss ABehr MAuer F: Accuracy of robot-assisted placement of lumbar and sacral pedicle screws: a prospective randomized comparison to conventional freehand screw implantation. Spine (Phila Pa 1976) 37:E496E5012012

  • 12

    Roser FTatagiba MMaier G: Spinal robotics: current applications and future perspectives. Neurosurgery 72 (Suppl 1):12182013

  • 13

    Schatlo BMartinez RAlaid Avon Eckardstein KAkhavan-Sigari RHahn A: Unskilled unawareness and the learning curve in robotic spine surgery. Acta Neurochir (Wien) 157:181918232015

  • 14

    Schatlo BMolliqaj GCuvinciuc VKotowski MSchaller KTessitore E: Safety and accuracy of robot-assisted versus fluoroscopy-guided pedicle screw insertion for degenerative diseases of the lumbar spine: a matched cohort comparison. J Neurosurg Spine 20:6366432014

  • 15

    Sukovich WBrink-Danan SHardenbrook M: Miniature robotic guidance for pedicle screw placement in posterior spinal fusion: early clinical experience with the SpineAssist. Int J Med Robot 2:1141222006

  • 16

    Tjardes TShafizadeh SRixen DPaffrath TBouillon BSteinhausen ES: Image-guided spine surgery: state of the art and future directions. Eur Spine J 19:25452010

  • 17

    Togawa DKayanja MMReinhardt MKShoham MBalter AFriedlander A: Bone-mounted miniature robotic guidance for pedicle screw and translaminar facet screw placement: part 2–Evaluation of system accuracy. Neurosurgery (2 Suppl 1) 60:ONS129ONS1392007

  • 18

    van Dijk JDvan den Ende RPJStramigioli SKöchling MHöss N: Clinical pedicle screw accuracy and deviation from planning in robot-guided spine surgery: robot-guided pedicle screw accuracy. Spine (Phila Pa 1976) 40:E986E9912015

  • 19

    Wang HZhou YLiu JHan JXiang L: Robot assisted navigated drilling for percutaneous pedicle screw placement: a preliminary animal study. Indian J Orthop 49:4524572015

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Article Information

Correspondence Granit Molliqaj, Service de Neurochirurgie, Faculté de Médecine, Hôpitaux Universitaires de Genève, 4 Rue Gabrielle Perret Gentil, Genève 1211, Switzerland. email: granitmolliqaj@gmail.com.

INCLUDE WHEN CITING DOI: 10.3171/2017.3.FOCUS179.

Disclosures Dr. Tessitore is a consultant for Mazor Robotics.

© AANS, except where prohibited by US copyright law.

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Figures

  • View in gallery

    CT scans demonstrating the Gertzbein-Robbins classification of screw positioning. The grades reflect the deviation of the screw from the “ideal” intrapedicular trajectory. Grade A is an intrapedicular screw without breach of the cortical layer of the pedicle; Grade B reflects a screw that breaches the cortical layer of the pedicle but does not exceed it laterally by > 2 mm. Grades C and D indicate a penetration of < 4 and < 6 mm, respectively. Grade E indicates a screw that does not pass through the pedicle or that, at any given point in its intended intrapedicular course, breaches the cortical layer of the pedicle in any direction by 6 mm or more. Modified with permission from Schatlo et al: J Neurosurg Spine 20:636–243, 2014.

References

1

Devito DPKaplan LDietl RPfeiffer MHorne DSilberstein B: Clinical acceptance and accuracy assessment of spinal implants guided with SpineAssist surgical robot: retrospective study. Spine (Phila Pa 1976) 35:210921152010

2

Gaines RW Jr: The use of pedicle-screw internal fixation for the operative treatment of spinal disorders. J Bone Joint Surg Am 82-A:145814762000

3

Gautschi OPSchatlo BSchaller KTessitore E: Clinically relevant complications related to pedicle screw placement in thoracolumbar surgery and their management: a literature review of 35,630 pedicle screws. Neurosurg Focus 31(4):E82011

4

Gertzbein SDRobbins SE: Accuracy of pedicular screw placement in vivo. Spine (Phila Pa 1976) 15:11141990

5

Hu XOhnmeiss DDLieberman IH: Robotic-assisted pedicle screw placement: lessons learned from the first 102 patients. Eur Spine J 22:6616662013

6

Hyun SJKim KJJahng TAKim HJ: Minimally invasive, robotic-vs. open fluoroscopic-guided spinal instrumented fusions—a randomized, controlled trial. Spine (Phila Pa 1976) [epub ahead of print]2016

7

Kantelhardt SRMartinez RBaerwinkel SBurger RGiese ARohde V: Perioperative course and accuracy of screw positioning in conventional, open robotic-guided and percutaneous robotic-guided, pedicle screw placement. Eur Spine J 20:8608682011

8

Kim HJJung WIChang BSLee CKKang KTYeom JS: A prospective, randomized, controlled trial of robot-assisted vs freehand pedicle screw fixation in spine surgery. Int J Med Robot [epub ahead of print]2016

9

Kim HJLee SHChang BSLee CKLim TOHoo LP: Monitoring the quality of robot-assisted pedicle screw fixation in the lumbar spine by using a cumulative summation test. Spine (Phila Pa 1976) 40:87942015

10

Pechlivanis IKiriyanthan GEngelhardt MScholz MLücke SHarders A: Percutaneous placement of pedicle screws in the lumbar spine using a bone mounted miniature robotic system: first experiences and accuracy of screw placement. Spine (Phila Pa 1976) 34:3923982009

11

Ringel FStüer CReinke APreuss ABehr MAuer F: Accuracy of robot-assisted placement of lumbar and sacral pedicle screws: a prospective randomized comparison to conventional freehand screw implantation. Spine (Phila Pa 1976) 37:E496E5012012

12

Roser FTatagiba MMaier G: Spinal robotics: current applications and future perspectives. Neurosurgery 72 (Suppl 1):12182013

13

Schatlo BMartinez RAlaid Avon Eckardstein KAkhavan-Sigari RHahn A: Unskilled unawareness and the learning curve in robotic spine surgery. Acta Neurochir (Wien) 157:181918232015

14

Schatlo BMolliqaj GCuvinciuc VKotowski MSchaller KTessitore E: Safety and accuracy of robot-assisted versus fluoroscopy-guided pedicle screw insertion for degenerative diseases of the lumbar spine: a matched cohort comparison. J Neurosurg Spine 20:6366432014

15

Sukovich WBrink-Danan SHardenbrook M: Miniature robotic guidance for pedicle screw placement in posterior spinal fusion: early clinical experience with the SpineAssist. Int J Med Robot 2:1141222006

16

Tjardes TShafizadeh SRixen DPaffrath TBouillon BSteinhausen ES: Image-guided spine surgery: state of the art and future directions. Eur Spine J 19:25452010

17

Togawa DKayanja MMReinhardt MKShoham MBalter AFriedlander A: Bone-mounted miniature robotic guidance for pedicle screw and translaminar facet screw placement: part 2–Evaluation of system accuracy. Neurosurgery (2 Suppl 1) 60:ONS129ONS1392007

18

van Dijk JDvan den Ende RPJStramigioli SKöchling MHöss N: Clinical pedicle screw accuracy and deviation from planning in robot-guided spine surgery: robot-guided pedicle screw accuracy. Spine (Phila Pa 1976) 40:E986E9912015

19

Wang HZhou YLiu JHan JXiang L: Robot assisted navigated drilling for percutaneous pedicle screw placement: a preliminary animal study. Indian J Orthop 49:4524572015

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