Surgical Workflow and Technical Tips for the Use of Intraoperative 3D Image and Navigation in Spine Surgery

Abstract

Navigated spinal surgery and intraoperative computed tomography (CT) scans are part of the modern armamentarium of spinal surgeons, improving the safety and accuracy of the procedures, facilitating from the correct implant insertion to the access of the degree of decompression. It is especially useful for minimally invasive spinal procedures, increasing precision and minimizing patient and surgeon exposure to continuous fluoroscopic radiation. However, little is known about the most appropriate workflow when using these technologies. In this paper, we presented a suggested, illustrated step-by-step, surgical workflow for using intraoperative CT scans and navigated spine surgery at different spinal segments. In our opinion, the implementation of the proposed routine in our institution has provided a smooth workflow, ultimately reduced procedure duration and increasing productivity.

 

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Resumo

A cirurgia de coluna com navegação e a tomografia computadorizada (TC) intraoperatória são parte do armamentário moderno dos cirurgiões de coluna, melhorando a segurança e a acurácia dos procedimentos, facilitando desde o posicionamento correto dos implantes até a avaliação do grau de descompressão. É especialmente útil em cirurgias de coluna minimamente invasivas, aumentando a precisão e minimizando a exposição do paciente e do cirurgião à radiação contínua da fluoroscopia. Entretanto, pouco se sabe sobre o melhor fluxo de trabalho no uso dessas tecnologias. Neste trabalho, apresentamos uma sugestão de fluxo de trabalho, ilustrado passo a passo, para o uso de TC intraoperatória e cirurgia de coluna com navegação em diferentes segmentos da coluna. Em nossa percepção, a implementação dessa rotina proposta em nossa instituição tem promovido um fluxo de trabalho suave, reduzindo, ultimamente, a duração e aumentando a produtividade.

 

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Keywords

intraoperative navigation - CT scan - spine surgery - workflow

Palavras-chave

navegação intraoperatória - TC - cirurgia de coluna - fluxo de trabalho

Introduction

Recent advances in intraoperative 3D images have revolutionized spine surgery because it allows direct navigation with real-time obtained images.[1] 3D cone beam CT (CBCT) produced non-distorted digital images that can be fully integrated into surgical navigation systems that can improve the accuracy of implant insertion as well as to check proper implant implantation intraoperatively, avoid revisions to misplacement.[1]

Despite higher costs when compared with conventional 2D radioscopy, in high-volume centers, the use of CBCT can reduce reoperation rates, being economically justified in the long term.[1] Additionally, total navigation spine surgery can eliminate the must for continuous fluoroscopic radiation, which can be extremely advantageous for patients and for surgeons.[2]

Image guidance with navigation can be used early from skin incision, to properly localize pathologic index level, as well as for implant insertion, increasing safety and accuracy of spinal procedures, especially in challenge cases or in minimally invasive procedures, minimizing exposure of soft tissues.[2]

However, despite the large number of studies about its safety, we have found scarce literature about the surgical workflow for routine use of intraoperative 3D images and navigation. The aim of this study is to describe the strategies of the senior author in a step-by-step manner of using intraoperative 3D image navigation surgery for posterior spinal procedures according to spine segment, aiming at avoiding an excessively time-consuming procedure as well as contamination of the surgical field.

 

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Technical Notes

After general anesthesia and neurophysiological monitoring, the patient is positioned prone after routine administration of antibiotics and tranexamic acid.

Craniocervical

• 1) the head is fixed in a Mayfield head holder or similar, and the CT scan is positioned at the caudal part of the table. A Jackson table, Allen table, or similar is necessary to free space caudally to the CT scan ([Figs. 1] and [2]).

• 2) After initial images are obtained, the CT scan is removed and parked caudally to the surgical table.

• 3) a conventional posterior midline approach is performed ([Fig. 3]).

• 4) implant insertion is guided by a navigation system and neurophysiological monitoring ([Fig. 3]).

• 5) decompression is performed, when necessary, as well as osteotomies.

• 6) After a final 3D image to check implant position and the extension of the decompression, the CT scan is again removed caudally.

• 7) Wound closure.

Fig. 1 Surgical setup for a posterior cervical (or craniocervical) approach – the reference frames with spheres (yellow arrows) are fixed preferentially to the head holder device.

Fig. 2 A and B, patient's final position. C and D, surgical setup - the reference frame (red arrow) of the neuronavigation (NN) is fixed to the head holder for acquiring 2D and 3D images prior to surgery initiation, which also helps identifying the spinal levels and incision marking.

Fig. 3 A and B, implants are inserted using navigation with real-time images (C). D, a final 3D image is obtained to check implants' position.

Similar steps are used for posterior cervical decompression (except for step 4), as described and illustrated in [Figure 4].

Fig. 4 Posterior cervical foraminotomy performed for three levels (C4-5, C5-6, and C6-7) after an anterior cervical discectomy and fusion at C6-7. A, patient is positioned with the neck slightly flexed and fixed in the head holder. B, once 3D CT images are obtained, the CT scan is removed caudally and NN is used to plan the incision. The wound is opened (C) and the proper level is checked with navigation (D). E, intraoperative final image is obtained to check proper decompression.

 

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Thoracolumbar

• 1) With the patient prone, an initial 2D image is obtained to check the goal levels. The CT scan is positioned at the caudal part of the table. A Jackson table, Allen table, or similar is necessary to free space caudally to the CT scan ([Fig. 5]).

• 2) A conventional posterior midline approach is made, and the navigated screws are implanted in the four to five caudal levels to the reference frame, as precision can be impaired with more distant vertebrae, guided by neurophysiological monitoring. If more than five levels will be implanted, the reference frame is repositioned ([Fig. 6]).

• 3) If needed, decompression and osteotomies may be performed.

• 4) A final 3D image is obtained ([Fig. 7]).

• 5) Wound closure.

Fig. 5 Surgical setup for thoracolumbar procedures. The reference frames (yellow arrows) with spheres are fixed preferentially in the most cranial spinous process of the segment to be operated after 2D image is obtained.

Fig. 6 A, spine exposure. B, the reference frame is attached to the most cranial spinous process and a 3D image is acquired. C, reposition of the reference frame at the caudal most implanted vertebra for imaging and a new set of implantations in the five next caudal levels.

Fig. 7 After screws insertion (A), the rods are implanted (B) and a final CT scan is performed to check final position (C and D).

In addition, it is possible to perform a posterior transforaminal interbody fusion using similar steps, as in the case shown in [Figure 8].

Fig. 8 A, surgical setup, and patient position. B, the skin over L2 (identified with 2D image) was incised and the reference frame was attached to the spinous process. C and D, navigated Jamshidi needle was used to canulate the pedicles of interest. E and F, navigated screws were inserted under navigation. G, microscope-aided decompression and interbody device through the left side. H – final image.

 

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Discussion

There is some evidence that intraoperative CT scans can improve the safety of implant insertion in spine surgeries. Steudel et al. (2011), in a prospective study of 100 patients with different spinal pathologies of which 80 had instrumentation, evaluated the role of helical CT performed intraoperatively in assessment the degree of decompression and implant position.[3] They reported that seven patients (8.75%) had inappropriately positioned implants and CT scan reduced the rate of second operations, as well as the need of a postoperative new image.

Bauer et al. (2018), in the same context, performed a prospective database review of two groups of 153 patients with adolescent idiopathic scoliosis (AIS) operated in two different periods of time – before and after intraoperative CT scan (for checking free-hand implanted screws) implementation.[4] In the pre-CT implementation group, two patients required revision for improper screw placement versus none in the post-CT implementation group (number needed to harm [NNH]= 76, absolute risk increase =1.31% [−0.49%, 3.11%]. They concluded that intraoperative CT was an effective tool for preventing reoperation in AIS surgery, especially in high-volume centers.

Considering navigated pedicle screws, Matur et al. (2023) performed a meta-analysis comparing robot-assisted or navigated pedicle screws with fluoroscopic freehand screws in the thoracolumbar spine.[5] Fourteen papers were evaluated (12 of them were randomized controlled trials), including 892 patients and 4046 screws. Despite no differences considering a return to the operating room for screw revision (relative risk [RR] 0.28, 95% confidence interval [CI] 0.07−1.13, p = 0.07) or nerve root injury (RR 0.50, 95% CI 0.11−2.30, p = 0.37), robot-assisted and navigated pedicle screws had higher odds of screw accuracy (OR 2.66, 95% CI 1.24−5.72, p = 0.01), and lower risk of facet joint violations (RR 0.09, 95% CI 0.02−0.38, p < 0.01) and major complications (RR 0.31, 95% CI 0.11−0.84, p = 0.02).

Despite the evidence of its safety and effectiveness, there is scarce literature about the surgical workflow of navigated pedicle screws. The higher cost initially perceived with the introduction of 3D image systems and navigation may be paid off in the long run, given its cost-effectiveness by avoiding reoperations and morbidity of misplaced instrumentation. Some scans can obtain a 3D scan in about 13 seconds, creating highly accurate intraoperative images without spending too much time.[6] These features would be of special interest for high-volume centers. Besides, navigated surgery reduces the surgeon exposure to continuous fluoroscopic radiation.[7] Using navigation system, some authors advocated that even for patients, the exposure of a navigated procedure is less intense than continuous fluoroscopic during percutaneous pedicle screw insertion.[8]

Limitations of navigated surgery consisted mainly in spinal shifts due to registration as well as the risk of contamination of the surgical field with inappropriate workflow. The navigation is not based on real-time images, which may not accurately represent the truth, especially when working distant from the reference frames (the reason why we recommended repositioning the reference frame and obtaining a new image after instrumentation of four to five levels).

 

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Conclusions

We described a suggested practical surgical workflow for the use of advanced intraoperative image in spine surgery for craniocervical and thoracolumbar procedures, including instrumentation and decompression. Despite potential criticism, advances in intraoperative imaging and navigation are the future and the present of modern spinal surgery; and it is important to know how to properly manage these technologies. This paper provides education on how to implement this technology in an optimized way (increasing efficiency and safety).

 

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Conflicts of Interest

None of the authors have conflicts of interest to disclose.

• References

• 1 Dea N, Fisher CG, Batke J. et al. Economic evaluation comparing intraoperative cone beam CT-based navigation and conventional fluoroscopy for the placement of spinal pedicle screws: a patient-level data cost-effectiveness analysis. Spine J 2016; 16 (01) 23-31
• 2 Navarro-Ramirez R, Lang G, Lian X. et al. Total Navigation in Spine Surgery; A Concise Guide to Eliminate Fluoroscopy Using a Portable Intraoperative Computed Tomography 3-Dimensional Navigation System. World Neurosurg 2017; 100: 325-335
• 3 Steudel WI, Nabhan A, Shariat K. Intraoperative CT in spine surgery. Acta Neurochir Suppl (Wien) 2011; 109: 169-174
• 4 Bauer JM, Moore JA, Rangarajan R. et al. Intraoperative CT Scan Verification of Pedicle Screw Placement in AIS to Prevent Malpositioned Screws: Safety Benefit and Cost. Spine Deform 2018; 6 (06) 662-668
• 5 Matur AV, Palmisciano P, Duah HO, Chilakapati SS, Cheng JS, Adogwa O. Robotic and navigated pedicle screws are safer and more accurate than fluoroscopic freehand screws: a systematic review and meta-analysis. Spine J 2023; 23 (02) 197-208
• 6 Otomo N, Funao H, Yamanouchi K, Isogai N, Ishii K. Computed Tomography-Based Navigation System in Current Spine Surgery: A Narrative Review. Medicina (Kaunas) 2022; 58 (02) 241 . Published 2022 Feb 5
• 7 Watkins RG, Gupta A, Watkins RG. Cost-effectiveness of image-guided spine surgery. Open Orthop J 2010; 4: 228-233 . Published 2010 Aug 6
• 8 Villard J, Ryang YM, Demetriades AK. et al. Radiation exposure to the surgeon and the patient during posterior lumbar spinal instrumentation: a prospective randomized comparison of navigated versus non-navigated freehand techniques. Spine 2014; 39 (13) 1004-1009

Publikationsverlauf

Eingereicht: 09. September 2024

Angenommen: 20. März 2025

Artikel online veröffentlicht:
16. Juli 2025