Spinal Navigation for Lateral Instrumentation of the Thoracolumbar Spine

BACKGROUND AND OBJECTIVES

Three-dimensional imaging-based navigation in spine surgery is mostly applied for pedicle screw placement. However, its potential reaches beyond. In this study, we analyzed the incorporation of spinal navigation for lateral instrumentation of the thoracolumbar spine in clinical routine at a high-volume spine center.

METHODS

Patients scheduled for lateral instrumentation were prospectively enrolled. A reference array was attached to the pelvis, and a computed tomography scan was acquired intraoperatively. A control computed tomography scan was routinely performed after final cage placement, replacing conventional 2-dimensional X-ray imaging.

RESULTS

145 cases were enrolled from April to October 2021 with a median of 1 (1-4) level being instrumented. Indications for surgery were trauma (35.9%), spinal infection (31.7%), primary and secondary tumors of the spine (17.2%), and degenerative spine disease (15.2%). The duration of surgery after the first scan was 98 ± 41 (20-342) minutes. In total, 190 cages were implanted (94 expandable cages for vertebral body replacement (49.5%) and 96 cages for interbody fusion [50.5%]). Navigation was successfully performed in 139 cases (95.9%). The intraoperative mental load was rated on a scale from 0 to 150 (maximal effort) by the surgeons, showing a moderate effort (median 30 [10-120]).

CONCLUSION

Three-dimensional imaging-based spinal navigation can easily be incorporated in clinical routine and serves as a reliable tool to achieve precise implant placement in lateral instrumentation of the spine. It helps to minimize radiation exposure to the surgical staff.

The Feasibility of 3D Intraoperative Navigation in Lateral Lumbar Interbody Fusion: Perioperative Outcomes, Accuracy of Cage Placement and Radiation Exposure

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To evaluate perioperative outcomes, accuracy of cage placement and radiation exposure in lateral lumbar interbody fusion (LLIF) using 3D intraoperative navigation (ION), compared to conventional 2D fluoroscopy only.

METHODS

The perioperative outcomes and accuracy of cage placement were examined in all patients who underwent LLIF using ION (ION group) or fluoroscopy only (non-ION group) by a single surgeon. The radiation exposure was examined in patients who underwent stand-alone LLIF.

RESULTS

A total of 87 patients with 154 levels (ION 49 patients with 79 levels/ non-ION 38 patients with 75 levels) were included. There were no significant differences in operative time (ION 143.5 min vs. non-ION 126.0 min, P = .406), time from induction end to surgery start (ION 31.0 min vs. non-ION 31.0 min, P = .761), estimated blood loss (ION 37.5 ml vs. non-ION 50.0 ml, P = .351), perioperative complications (ION 16.3% vs. non-ION 7.9%, P = .335) and length of stay (ION 50.6 hours vs. non-ION 41.7 hours, P = .841). No significant difference was found in the accuracy of cage placement (P = .279). ION did not significantly increase total radiation dose (ION 51.0 mGy vs. non-ION 47.4 mGy, P = .237) and tended to reduce radiation dose during the procedure (ION 32.2 mGy vs. non-ION 47.4 mGy, P = .932).

CONCLUSIONS

The perioperative outcomes, accuracy of cage placement and radiation exposure in LLIF using ION were comparable to those using fluoroscopy only. The use of ION in LLIF was feasible, safe and accurate and may reduce radiation dose to the surgeon and surgical team.

Cone-Beam Navigation Can Reduce the Radiation Exposure and Save Fusion Length-Dependent Operation Time in Comparison to Conventional Fluoroscopy in Pedicle-Screw-Based Lumbar Interbody Fusion

This study investigates the advantages and disadvantages of cone-beam-based navigated standardized posterior lumbar interbody fusion surgery (PLIF), regarding the radiation exposure and perioperative time management, compared to the use of fluoroscopy. Patients treated receiving an elective one- to three-level PLIF were retrospectively enrolled in the study. The surgery time, preparation time, operation room time, and effective dose (mSv) were analyzed for comparison of the radiation exposure and time consumption between cone-beam and fluoroscopy; Results: 214 patients were included (108 cone-beam navigated, and 106 traditional fluoroscopies). Using cone-beam navigation, reductions in the effective dose (2.23 ± 1.96 mSv vs. 3.39 ± 2.32 mSv, p = 0.002) and mean surgery time of 30 min (143.62 ± 43.87 min vs. 171.10 ± 48.91 min, p < 0.001) were demonstrated, which leveled out the extended preparation time of 7−8 min (37.25 ± 9.99 min vs. 29.65 ± 7.69 min, p < 0.001). These effects were fusion length dependent and demonstrated additional benefits in multisegmental surgeries. The cone-beam navigation system led to a reduction in the perioperative time requirements and radiation exposure. Furthermore, the controversially discussed longer preparation time when using cone-beam navigation was amortized by a shortened surgery time, especially in multilevel surgery.

Novel Applications of Spinal Navigation in Deformity and Oncology Surgery-Beyond Screw Placement

Computer-assisted navigation has made a major impact on spine surgery, providing surgeons with technological tools to safely place instrumentation anywhere in the spinal column. With advances in intraoperative image acquisition, registration, and processing, many surgeons are now using navigation in their practices. The incorporation of navigation into the workflow of surgeons continues to expand with the evolution of minimally invasive techniques and robotic surgery. While numerous investigators have demonstrated the benefit of navigation for improving the accuracy of instrumentation, few have reported applying this technology to other aspects of spine surgery. Surgeries to correct spinal deformities and resect spinal tumors are technically demanding, incorporating a wide range of techniques not only for instrumentation placement but also for osteotomy planning and executing the goals of surgery. Although these subspecialties vary in their objectives, they share similar challenges with potentially high complications, invasiveness, and consequences of failed execution. Herein, we highlight the utility of using spinal navigation for applications beyond screw placement: specifically, for planning and executing osteotomies and guiding the extent of tumor resection. A narrative review of the work that has been done is supplemented with illustrative cases demonstrating these applications.

Intraoperative Computed Tomography-Based Navigation with Augmented Reality for Lateral Approaches to the Spine

Background. Lateral approaches to the spine have gained increased popularity due to enabling minimally invasive access to the spine, less blood loss, decreased operative time, and less postoperative pain. The objective of the study was to analyze the use of intraoperative computed tomography with navigation and the implementation of augmented reality in facilitating a lateral approach to the spine. Methods. We prospectively analyzed all patients who underwent surgery with a lateral approach to the spine from September 2016 to January 2021 using intraoperative CT applying a 32-slice movable CT scanner, which was used for automatic navigation registration. Sixteen patients, with a median age of 64.3 years, were operated on using a lateral approach to the thoracic and lumbar spine and using intraoperative CT with navigation. Indications included a herniated disc (six patients), tumors (seven), instability following the fracture of the thoracic or lumbar vertebra (two), and spondylodiscitis (one). Results. Automatic registration, applying intraoperative CT, resulted in high accuracy (target registration error: 0.84 ± 0.10 mm). The effective radiation dose of the registration CT scans was 6.16 ± 3.91 mSv. In seven patients, a control iCT scan was performed for resection and implant control, with an ED of 4.51 ± 2.48 mSv. Augmented reality (AR) was used to support surgery in 11 cases, by visualizing the tumor outline, pedicle screws, herniated discs, and surrounding structures. Of the 16 patients, corpectomy was performed in six patients with the implantation of an expandable cage, and one patient underwent discectomy using the XLIF technique. One patient experienced perioperative complications. One patient died in the early postoperative course due to severe cardiorespiratory failure. Ten patients had improved and five had unchanged neurological status at the 3-month follow up. Conclusions. Intraoperative computed tomography with navigation facilitates the application of lateral approaches to the spine for a variety of indications, including fusion procedures, tumor resection, and herniated disc surgery.

Intraoperative image guidance for lateral position surgery

Recent advances in minimally invasive spine surgery techniques have precipitated the popularity of lateral position spine surgery, such as lateral lumbar interbody fusion (LLIF) and oblique lumbar interbody fusion (OLIF). Lateral position surgery offers a unique, minimally invasive approach to the lumbar spine that allows for preservation of anterior and posterior spinal elements. Traditionally, surgeons have relied upon fluoroscopy for triangulation and implant placement. Over the last decade, intraoperative 3-dimensional navigation (ION) has risen to the forefront of innovation in LLIF and OLIF. This technology utilizes intra-operative advanced imaging, such as comminuted tomography (CT), to map the patient’s 3D anatomy and allows the surgeon to accurately visualize instruments and implants in spatial relationship to the patient’s anatomy in real time. ION has the potential to improve accuracy during instrumentation, decrease operating room times, lower radiation exposure to the surgeon and staff, and increase feasibility of single-position surgery during which the spine is instrumented both laterally and posteriorly while the patient remains in the lateral decubitus position. Despite the advantages of ION, the intra-operative radiation exposure risk to patients is controversial. Future directions include continued innovation in ultra low radiation imaging (ULRI) techniques and image enhancement technology and in uses of robot-assisted navigation in single-position spine surgery.

The feasibility of computer-assisted 3D navigation in multiple-level lateral lumbar interbody fusion in combination with posterior instrumentation for adult spinal deformity

OBJECTIVE

The lateral lumbar interbody fusion (LLIF) technique is used to treat many common spinal degenerative pathologies including kyphoscoliosis. The use of spinal navigation for LLIF has not been broadly adopted, especially in adult spinal deformity. The purpose of this study was to evaluate the feasibility as well as the intraoperative and navigation-related complications of computer-assisted 3D navigation (CaN) during multiple-level LLIF for spinal deformity.

METHODS

Retrospective analysis of clinical and operative characteristics was performed for all patients > 18 years of age who underwent multiple-level CaN LLIF combined with posterior instrumentation for adult spinal deformity at the University of Michigan between 2014 and 2020. Intraoperative CaN-related complications, LLIF approach–related postoperative complications, and medical postoperative complications were assessed.

RESULTS

Fifty-nine patients were identified. The mean age was 66.3 years (range 42–83 years) and body mass index was 27.6 kg/m2 (range 18–43 kg/m2). The average coronal Cobb angle was 26.8° (range 3.6°–67.0°) and sagittal vertical axis was 6.3 cm (range −2.3 to 14.7 cm). The average number of LLIF and posterior instrumentation levels were 2.97 cages (range 2–5 cages) and 5.78 levels (range 3–14 levels), respectively. A total of 6 intraoperative complications related to the LLIF stage occurred in 5 patients. Three of these were CaN-related and occurred in 2 patients (3.4%), including 1 misplaced lateral interbody cage (0.6% of 175 total lateral cages placed) requiring intraoperative revision. No patient required a return to the operating room for a misplaced interbody cage. A total of 12 intraoperative complications related to the posterior stage occurred in 11 patients, with 5 being CaN-related and occurring in 4 patients (6.8%). Univariate and multivariate analyses revealed no statistically significant risk factors for intraoperative and CaN-related complications. Transient hip weakness and numbness were found to be in 20.3% and 22.0% of patients, respectively. At the 1-month follow-up, weakness was observed in 3.4% and numbness in 11.9% of patients.

CONCLUSIONS

Use of CaN in multiple-level LLIF in the treatment of adult spinal deformity appears to be a safe and effective technique. The incidence of approach-related complications with CaN was 3.4% and cage placement accuracy was high.

The Navigated Oblique Lumbar Interbody Fusion: Accuracy Rate, Effect on Surgical Time, and Complications

Objective

The oblique lumbar interbody fusion (OLIF) can be done with either fluoroscopy or navigation. However, it is unclear how navigation affects the overall flow of the procedure. We wished to report on the accuracy of this technique using navigation and on how navigation affects surgical time and complications.

Methods

A retrospective review was undertaken to evaluate patients who underwent OLIF using spinal navigation at University of California San Francisco. Data collected were demographic variables, perioperative variables, and radiographic images. Postoperative lateral radiographs were analyzed for accuracy of cage placement. The disc space was divided into 4 quadrants from anterior to posterior, zone 1 being anterior, and zone 4 being posterior. The accuracy of cage placement was assessed by placement.

Results

There were 214 patients who met the inclusion criteria. A total of 350 levels were instrumented from L1 to L5 using navigation. The mean follow-up time was 17.42 months. The mean surgical time was 211 minutes, and the average surgical time per level was 129.01 minutes. After radiographic analysis, 94.86% of cages were placed within quartiles 1 to 3. One patient (0.47%) underwent revision surgery because of suboptimal cage placement. For approach-related complications, transient neurological symptoms were 10.28%, there was no vascular injury.

Conclusion

The use of navigation to perform OLIF from L1 to L5 resulted in a cage placement accuracy rate of 94.86% in 214 patients.