Robotic pedicle screw placement

Robotic pedicle screw placement

Robotic spinal fixation is associated with increased screw placement accuracy and similar operative blood loss, length of stay, and operative duration. These findings support the safety and cost-effectiveness of robotic spinal surgery across the spectrum of robotic systems and screw types 1).


In addition to demonstrating excellent pedicle screw accuracy, early studies have explored the impact of robot-assisted spine surgery on reducing radiation time, length of hospital stay, operative time, and perioperative complications in comparison to conventional freehand technique. The Mazor X Stealth Edition was introduced in 2018. This robotic system integrates Medtronic’s Stealth navigation technology into the Mazor X platform, which was introduced in 2016. It is unclear what the impact of these advancements have made on clinical outcomes.


In a multicenter study, both robot systems achieved excellent screw accuracy and low robot time per screw. However, using Stealth led to significantly less fluoroscopic radiation time, lower robot abandonment rates, and reduced blood transfusion rates than Mazor X. Other factors including length of stay, and 90-day complications were similar 2)

Ha Y. Robot-Assisted Spine Surgery: A Solution for Aging Spine Surgeons. Neurospine. 2018 Sep;15(3):187-188. doi: 10.14245/ns.18edi.003. Epub 2018 Sep 11. PubMed PMID: 30196675.


In three cadavers 12 pedicle screws were implanted in thoraco-lumbar segments with the robotic surgery assistant. 3D-fluoroscopy was performed for preoperative referencing, planning and identification of postoperative screw position. The radiation exposure of fluoroscopy and a CT scanner was compared, measuring the Computed Tomography Dose Index (CTDIw ).

Pedicle screw positioning was graded according to the Gertzbein-Robbins classification: Eleven of 12 pedicle screws showed optimal transpedicular position (Grade 1), one was positioned less than 2 mm outside (Grade 2). No major deviations were observed. Referencing with 3D-fluoroscopy resulted in a CTDIw reduction of 84% in the cervical- and 33% in the lumbar spine.

Robot-guided PS placement, using 3D-fluoroscopy for referencing, is a reliable tool for minimally invasive PS implantation; radiation exposure can be reduced 3).


Menger et al., investigated the cost effectiveness of adding robotic technology in spine surgery to an active neurosurgical practice.

The time of operative procedures, infection rates, revision rates, length of stay, and possible conversion of open to minimally invasive spine surgery (MIS) secondary to robotic image guidance technology were calculated using a combination of institution-specific and national data points. This cost matrix was subsequently applied to 1 year of elective clinical case volume at an academic practice with regard to payor mix, procedural mix, and procedural revenue.

A total of 1,985 elective cases were analyzed over a 1-year period; of these, 557 thoracolumbar cases (28%) were analyzed. Fifty-eight (10.4%) were MIS fusions. Independent review determined an additional ~10% cases (50) to be candidates for MIS fusion. Furthermore, 41.4% patients had governmental insurance, while 58.6% had commercial insurance. The weighted average diagnosis-related group reimbursement for thoracolumbar procedures for the hospital system was calculated to be $25,057 for Medicare and $42,096 for commercial insurance. Time savings averaged 3.4 minutes per 1-level MIS procedure with robotic technology, resulting in annual savings of $5,713. Improved pedicle screw accuracy secondary to robotic technology would have resulted in 9.47 revisions being avoided, with cost savings of $314,661. Under appropriate payor mix components, robotic technology would have converted 31 Medicare and 18 commercial patients from open to MIS. This would have resulted in 140 fewer total hospital admission days ($251,860) and avoided 2.3 infections ($36,312). Robotic surgery resulted in immediate conservative savings estimate of $608,546 during a 1-year period at an academic center performing 557 elective thoracolumbar instrumentation cases.

Application of robotic spine surgery is cost-effective, resulting in lesser revision surgery, lower infection rates, reduced length of stay, and shorter operative time. Further research is warranted, evaluating the financial impact of robotic spine surgery 4).


Several randomized controlled trials (RCTs) and cohort studies involving robotic-assisted (RA) and free-hand with fluoroscopy-guided (FH) and published before January 2017 were searched for using the Cochrane LibraryOvidWeb of SciencePubMed, and EMBASE databases. A total of 55 papers were selected. After the full-text assessment, 45 clinical trials were excluded. The final meta-analysis included 10 articles.

The accuracy of pedicle screw placement within the RA group was significantly greater than the accuracy within the FH group (odds ratio 95%, “perfect accuracy” confidence interval: 1.38-2.07, P < .01; odds ratio 95% “clinically acceptable” Confidence Interval: 1.17-2.08, P < .01).

There are significant differences in accuracy between RA surgery and FH surgery. It was demonstrated that the RA technique is superior to the conventional method in terms of the accuracy of pedicle screw placement 5).


In 2013 a study evaluated the outcomes of robotic-assisted screw placement in a consecutive series of 102 patients.

Data were recorded from technical notes and operative records created immediately following each surgery case, in which the robotic system was used to guide pedicle screw placement. All cases were performed at the same hospital by a single surgeon. The majority of patients had spinal deformity and/or previous spine surgery. Each planned screw placement was classified as: (1) successful/accurately placed screw using robotic guidance; (2) screw malpositioned using robot; (3) use of robot aborted and screw placed manually; (4) planned screw not placed as screw deemed non essential for construct stability. Data from each case were reviewed by two independent researchers to indentify the diagnosis, number of attempted robotic guided screw placements and the outcome of the attempted placement as well as complications or reasons for non-placement.

Robotic-guided screw placement was successfully used in 95 out of 102 patients. In those 95 patients, 949 screws (87.5 % of 1,085 planned screws) were successfully implanted. Eleven screws (1.0 %) placed using the robotic system were misplaced (all presumably due to “skiving” of the drill bit or trocar off the side of the facet). Robotic guidance was aborted and 110 screws (10.1 %) were manually placed, generally due to poor registration and/or technical trajectory issues. Fifteen screws (1.4 %) were not placed after intraoperative determination that the screw was not essential for construct stability. The robot was not used as planned in seven patients, one due to severe deformity, one due to very high body mass index, one due to extremely poor bone quality, one due to registration difficulty caused by previously placed loosened hardware, one due to difficulty with platform mounting and two due to device technical issues.

Of the 960 screws that were implanted using the robot, 949 (98.9 %) were successfully and accurately implanted and 11 (1.1 %) were malpositioned, despite the fact that the majority of patients had significant spinal deformities and/or previous spine surgeries. “Tool skiving” was thought to be the inciting issue with the misplaced screws. Intraoperative anteroposterior and oblique fluoroscopic imaging for registration is critical and was the limiting issue in four of the seven aborted cases 6).

Robotic pedicle screw placement learning curve.


1)

Himstead AS, Shahrestani S, Brown NJ, Produturi G, Shlobin NA, Al Jammal O, Choi EH, Ransom SC, Daniel Diaz-Aguilar L, Sahyouni R, Abraham M, Pham MH. Bony fixation in the era of spinal robotics: A systematic review and meta-analysis. J Clin Neurosci. 2022 Jan 19;97:62-74. doi: 10.1016/j.jocn.2022.01.005. Epub ahead of print. PMID: 35065405.
2)

Lee NJ, Zuckerman SL, Buchanan IA, Boddapati V, Mathew J, Leung E, Park PJ, Pham MH, Buchholz AL, Khan A, Pollina J, Mullin JP, Jazini E, Haines C, Schuler TC, Good CR, Lombardi JM, Lehman RA. Is There a Difference Between Navigated and Non-Navigated Robot Cohorts in Robot-Assisted Spine Surgery? A Multicenter, Propensity-Matched Analysis of 2,800 Screws and 372 Patients. Spine J. 2021 May 19:S1529-9430(21)00253-9. doi: 10.1016/j.spinee.2021.05.015. Epub ahead of print. PMID: 34022461.
3)

Spyrantis A, Cattani A, Seifert V, Freiman TM, Setzer M. Minimally invasive percutaneous robotic thoracolumbar pedicle screw implantation combined with three-dimensional-fluoroscopy can reduce radiation: a cadaver and phantom study. Int J Med Robot. 2019 Jun 19:e2022. doi: 10.1002/rcs.2022. [Epub ahead of print] PubMed PMID: 31216120.
4)

Menger RP, Savardekar AR, Farokhi F, Sin A. A Cost-Effectiveness Analysis of the Integration of Robotic Spine Technology in Spine Surgery. Neurospine. 2018 Aug 29. doi: 10.14245/ns.1836082.041. [Epub ahead of print] PubMed PMID: 30157583.
5)

Fan Y, Du JP, Liu JJ, Zhang JN, Qiao HH, Liu SC, Hao DJ. Accuracy of pedicle screw placement comparing robot-assisted technology and the free-hand with fluoroscopy-guided method in spine surgery: An updated meta-analysis. Medicine (Baltimore). 2018 Jun;97(22):e10970. doi: 10.1097/MD.0000000000010970. Review. PubMed PMID: 29851848; PubMed Central PMCID: PMC6392558.
6)

Hu X, Ohnmeiss DD, Lieberman IH. Robotic-assisted pedicle screw placement: lessons learned from the first 102 patients. Eur Spine J. 2013 Mar;22(3):661-6. doi: 10.1007/s00586-012-2499-1. Epub 2012 Sep 14. PubMed PMID: 22975723; PubMed Central PMCID: PMC3585630.

Posterior cervical decompression

Posterior cervical decompression

Not typically used for a herniated cervical disc, more common for cervical spinal stenosisOPLL

● without posterior fusion

● with lateral mass fusion

b) keyhole laminotomy: sometimes permits removal of disc fragment

Usually reserved for the following conditions:

multiple cervical discs or osteophytes (anterior cervical discectomy (ACD) is usually used to treat only 2, or possibly 3, levels without) with myelopathy.

where the anterior pathology is superimposed on cervical stenosis, and the latter is more diffuse and/or more significant

in professional speakers or singers where the 4% risk of permanent voice change due to recurrent laryngeal nerve injury with ACD may be unacceptable.


Laminectomy and facetectomy are commonly used surgical procedures for decompressing cervical spinal stenosis. Resection of the posterior structures causes instability and affects the internal stresses of the cervical spinal components. However, the influence of these surgical procedures on the biomechanical responses of the cervical spine has not been studied.

A nonlinear finite element model of the intact C2-C7 was constructed and validated. Ten surgically altered models were created from the intact model and were tested under physiologic loading. Because of the inclusion of five motion segments, it was possible to determine the intersegmental responses and internal cortical shell and disc stresses in the adjacent altered and unaltered spinal components.

Under combined flexion and extension, intersegmental motions at C4-C5 and C5-C6 increased significantly after C5 laminectomy. Subsequent facetectomy performed at C5 and C6 on the laminectomized model only affected the responses at the C5-C6 segment. Overall, slight intersegmental responses of up to 5% were observed at the adjacent levels of C3-C4 and C6-C7. Laminectomy did not cause any significant increase in the intersegmental motions under lateral bending and axial rotation. Extending the surgical procedures to unilateral and bilateral facetectomy only increased the intersegmental motions slightly. Similar increases in the intervertebral disc and the cortical shell stresses were observed. These findings may partially explain the clinical observations of enhanced osteophytes formation.

This study provides a better understanding of the surgically altered cervical spinal biomechanics and may help formulate treatment strategies such as spinal implants 1).


Its a posterior cervical spine surgery, for cervical spinal stenosis. The spine surgeon removes a small section of the lamina to relieve compression on the nerve. The remaining spinal bones are connected back together with titanium metal rods and screws.

The skin incision is in the midline of the back of the neck and is about 3 to 4 inches long. The paraspinal muscles are then elevated from multiple levels. Removal of the lamina. A high-speed burr can be used to make a trough in the lamina on both sides right before it joins the facet joint. The lamina with the spinous process can then be removed as one piece (like a lobster tail). Removal of the lamina and spinous process allows the spinal cord to float backwards and gives it more room.


Cervical laminectomy resulted in the greatest increase in global cervical ROM. Resection of the intraspinous and supraspinous ligaments [ISLs).ISLs at C2-3 and C7-T1 increased segmental ROM at these specific levels to a similar extent that laminectomy increased ROM at each cervical level. This segmental ROM may contribute to pain or postprocedural deformity and highlights the importance of the ISLs at the terminal ends of the cervical open door laminoplasty (ODL) 2).

Cervical laminectomy complications.

Prone, some use pin head holder

a) C-arm

b) high speed drill

  1. implants: cervical lateral mass screws and rods if fusion is being done

4. neuromonitoring: some surgeons used SSEP/MEP: Use of intra-op EP monitoring during a routine surgery for CSM or cervical radiculopathy is not recommended as an indication to alter the surgical plan or administer steroids since this paradigm has not been observed to reduce the incidence of neurologic injury (Level D Class III).

5. consent (in lay terms for the patient—not all-inclusive):

a) procedure: surgery through the back of the neck to remove the bone over the compressed spinal cord and nerves and possibly to place screws and rods to fuse the boned together

b) alternatives: nonsurgical management, surgery from the front of the neck, posterior surgery without fusion, laminoplasty

c) complications: nerve root weakness (C5 nerve root is the most common), may not relieve symptoms, further surgery may be needed, possible seizures with MEPs. If fusion is not done, there is a risk of progressive bone slippage, which would require further surgery.

Posterior cervical decompression and fusion.

Posterior fossa decompression for Chiari type 1 deformity.


1)

Hong-Wan N, Ee-Chon T, Qing-Hang Z. Biomechanical effects of C2-C7 intersegmental stability due to laminectomy with unilateral and bilateral facetectomy. Spine (Phila Pa 1976). 2004 Aug 15;29(16):1737-45; discussion 1746. PubMed PMID: 15303016.
2)

Healy AT, Lubelski D, West JL, Mageswaran P, Colbrunn R, Mroz TE. Biomechanics of open-door laminoplasty with and without preservation of posterior structures. J Neurosurg Spine. 2016 May;24(5):746-51. doi: 10.3171/2015.7.SPINE15229. Epub 2016 Jan 22. PubMed PMID: 26799115.

Thoracic spine approaches

Thoracic spine approaches

Since the end of the nineteenth century, the wide dissemination of Pott’s disease has ignited debates about which should be the ideal route to perform ventrolateral decompression of the dorsal rachis in case of paraplegia due to spinal cord compression in tuberculosis spondylitis. It was immediately clear that the optimal approach should be the one minimizing the surgical manipulation on both neural and extra-neural structures, while optimizing the exposure and surgical maneuverability on the target area. The first attempt was reported by Victor Auguste Menard in 1894, who described, for the first time, a completely different route from traditional laminectomy, called costotransversectomy. The technique was conceived to drain tubercular paravertebral abscesses causing paraplegia without manipulating the spinal cord 1).

The procedure defined by Capener in 1954 2) resulted in better results for the treatment of spinal tuberculosis, due to the effect of antibiotic3)

Over the following decades many other routes have been described all over the world, thus demonstrating the wide interest on the topic. Surgical development has been marked by the new technical achievements and by instrumental/technological advancements, until the advent of portal surgery and endoscopy-assisted techniques. Gagliardi et al. retraced the milestones of this history up to 2022, through a systematic review on the topic 4).


Thoracic disc herniation surgery is challenging because of: the difficulty of anterior approaches, the proportionately tighter space between cord and canal compared to the cervical and lumbar regions, and the watershed blood supply which creates a significant risk of spinal cord injury with attempts to manipulate the cord when trying to work anteriorly to it from a posterior approach. Thoracic disc herniations are calcified in 65% of patients considered for surgery 5) (more difficult to remove from a posterior or lateral approach than non-calcified discs).

For centrally located anterior access: a transthoracic or lateral approach gives the best acess. Some prefer a left-sided approach to avoid the vena cava, others prefer a right-sided approach because the heart does not impede access.


Various different approaches have been tried for the surgical removal of TDH, but most of them are cumbersome surgeries such as thoracotomy or thoracoscopic or anterior approaches with or without instrumentation. The requirement for a simplified, familiar, and less morbid surgery has motivated some new approaches. A pedicle sparing transfacet approach (PSTA) was first described in 1995, but to date no sufficient clinical series has been presented in the literature to report on its feasibility and applicability along with complication and morbidity rates.

Surgery for thoracic disc herniation is comparatively rare and often demanding. The goal is to achieve sufficient decompression without manipulating the spinal cord. Individual planning and various surgical techniques and approaches are required.

Surgical treatment can be divided into anterior, lateral and posterior approaches and is an area of contention in the literature. Available evidence consists mostly of single-arm, single-institutional studies with limited sample sizes.

Anterior approaches had longer LOS and higher, although not statistically significant, complication rates. No difference was found with regard to discharge disposition. In light of these findings, surgeons should weigh the risks and benefits of each surgical technique during tailoring of decision making 6).

The approach is dependent on the location, the magnitude, and the consistency of the herniated thoracic disc.

Medially located large calcified discs should be operated through an anterolateral transthoracic approach, whereas noncalcified or lateral herniated discs can be treated from a posterior approach as well. For optimal treatment of this rare entity, the treatment should be performed in selected centers 7).

Anterolateral retroperitoneal, anterior transthoracic, posterolateral, and lateral approaches are performed in discectomy with or without fusion and internal fixation. However, patients who have undergone any operation at these levels are predisposed to postoperative recurrence, neurological aggravation, and adjacent segment degeneration, and the outcomes are inferior than those in lower lumbar spine 8) 9).


posterior (midline laminectomy): primary indication is for decompression of posteriorly situated intracanalicular pathology (e.g. metastatic tumor) especially over multiple levels. There is a high failure and complication rate when used for single-level anterior pathology (e.g. midline disc herniation)

a) lateral gutter: laminectomy plus removal of pedicle

b) transpedicular approach 10)

c) costotransversectomy

d) Pedicle sparing transfacet approach

(transthoracic approach): usually through the pleural space

(retrocoelomic) 11) : an approach posterior (external) to the pleural space

Video-assisted thoracoscopic surgery is an alternative to open surgical approaches 12) 13).


1)

Ménard V. Causes de la paraplégie dans le mal de Pott. Son traitement chirurgical par l’ouverture directe du foyer tuberculeux des vertebres. Rev Orthop 1894; 5: 47-64.
2)

CAPENER N. The evolution of lateral rhachotomy. J Bone Joint Surg Br. 1954 May;36-B(2):173-9. doi: 10.1302/0301-620X.36B2.173. PMID: 13163099.
3)

Benzel EC. Spine Surgery: Techniques, Complication Avoidance, and Management, 3th Ed. Saunders, Philadelphia 2012.
4)

Gagliardi F, Pompeo E, De Domenico P, Snider S, Roncelli F, Acerno S, Mortini P. HISTORY OF EVOLUTION OF POSTERO-LATERAL APPROACHES TO THE THORACIC SPINE: FROM CURE OF POTT’S DISEASE TO EPIDURAL TUMOR RESECTION. J Neurol Surg A Cent Eur Neurosurg. 2022 Jan 10. doi: 10.1055/a-1734-2085. Epub ahead of print. PMID: 35008121.
5) , 12)

Stillerman CB, Chen TC, Couldwell WT, et al. Experience in the surgical management of 82 symptomatic herniated thoracic discs and review of the literature. J Neurosurg. 1998; 88:623–633
6)

Kerezoudis P, Rajjoub KR, Goncalves S, Alvi MA, Elminawy M, Alamoudi A, Nassr A, Habermann EB, Bydon M. Anterior versus posterior approaches for thoracic disc herniation: Association with postoperative complications. Clin Neurol Neurosurg. 2018 Apr;167:17-23. doi: 10.1016/j.clineuro.2018.02.009. Epub 2018 Feb 6. PubMed PMID: 29428625.
7)

Arts MP, Bartels RH. Anterior or posterior approach of thoracic disc herniation? A comparative cohort of mini-transthoracic versus transpedicular discectomies. Spine J. 2013 Oct 24. pii: S1529-9430(13)01595-7. doi: 10.1016/j.spinee.2013.09.053. [Epub ahead of print] PubMed PMID: 24374099.
8)

Sanderson SP, Houten J, Errico T, et al. The unique characteristics of “upper” lumbar disc herniations. Neurosurgery 2004;55:385–9.
9)

Ido K, Shimizu K, Tada H, et al. Considerations for surgical treatment of patients with upper lumbar disc herniations. J Spinal Disord 1998;11:75–9.
10)

Le Roux PD, Haglund MM, Harris AB. Thoracic Disc Disease: Experience with the Transpedicular Approach in Twenty Consecutive Patients. Neurosurgery. 1993; 33:58–66
11)

Uribe JS, Smith WD, Pimenta L, et al. Minimally invasive lateral approach for symptomatic thoracic disc herniation: initial multicenter clinical experience. J Neurosurg Spine. 2012; 16:264–27
13)

Dohn DF. Thoracic Spinal Cord Decompression: Alternative Surgical Approaches and Basis of Choice. Clin Neurosurg. 1980; 27:611–623
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