A Single-Center Experience of Robotic- Assisted Spine Surgery of 150 cases: Analysis of Screw Accuracy, Superior Facet Joint Violation

Introduction

In recent years, navigational robotic technology has gained significant interest worldwide including its application in spine surgery. The introduction of robotic-assisted navigation devices, which provide precise and accurate guiding during difficult spine surgeries, is a significant accomplishment in this discipline. These technologies help surgeons place implants accurately by providing real-time images and computer-guided instruments. Surgeons performing spine procedures can obtain better surgical results, fewer challenges, and more patient safety using navigational robotic technology.¹ Robotic technology improves pedicle screw precision and reduces radiation exposure.² All things considered, navigational robotic technology has great promise for transforming spine surgery and enhancing patient care in the future. As this technology develops further, there is a great deal of potential for improvements in the field of spine surgery. Through this paper, we are sharing our initial experience and results.

Materials And Methods

Patient demographic characteristics: This study included 150 participants with an average age of 64.1 years (±10.98), consisting of 42 males and 108 females. The average BMI (Body Mass Index) was 27.4 kg/m² (±2.04). Participants were categorized based on ASA (American Society of Anaesthesiologists) grades: Grade 1 (n=12), Grade 2 (n=108), Grade 3 (n=24), and Grade 4 (n=6). Surgery types included 132 primary procedures and 18 revisions. A total of 696 pedicle screws were inserted across different surgical levels, The most frequent surgical levels were L4-L5 (n=97), followed by L5-S1 (n=48) and L3-L4 (n=27). Table 1 summarizes the study participants' demographic profile, surgical characteristics, and procedural details.

Table 1: Demographic details of patients

Abbreviations: BMI-Body mass index, ASA- American Society of Anaesthesiologists, CT-Computed tomography, TLIF Transforaminal Lumbar Interbody Fusion.

Inclusion criteria:

1. Patients who underwent Transforaminal Lumbar Interbody Fusion (TLIF) using robotic assistance for lumbar degenerative disc, lumbar spondylolisthesis, severe spinal stenosis, and facet joint arthropathy
2. Patients older than 35 years of age
3. Patients who had given consent for the study

Exclusion criteria:

1. Patients with trauma, infection, and tumour etiology affecting spine
2. Patients younger than 35 years
3. Patients in whom robot was not used during surgery
4. Patients who did not give consent for the study

Evaluation:

A postoperative Computed Tomography (CT) scan of the lumbar spine was performed on each of our patients to assess for pedicle breach and Superior facet joint violation (SFJ). Using Gertzbein Robbins classification3 (Figure 1), the accuracy of the pedicle screw was examined.

Figure 1: Gertzbein-Robbins classification showing grades of breach from Grade 0 to 3

• Grade 0: No pedicle perforation
• Grade 1: Two millimetre of threads are present outside the pedicle
• Grade 2: Two to four millimetre of core screw diameter are present outside the pedicle
• Grade 3: The entire screw is present outside the pedicle

Grades 0 and 1 are clinically suitable screw placements4; nevertheless, grade 2, 3 medial perforations suggest severe perforations. We also evaluated the facet joint violation grade according to Yson et al.5 (Figure 2).

Figure 2: Yson classification for superior facet joint violation

• Grade 0: No facet joint violation
• Grade 1: Facet joint contact
• Grade 2: Facet joint penetration

Also, in our study, we analysed effective radiation dose exposure in millisievert (mSV) in the two groups, namely preoperative + intraoperative (PO+IO) radiation dose and intraoperative radiation (IO) dose. The first group represents the amount of radiation patient is subjected to and the second group represents the amount of radiation to health care personnel (surgeons and operation theatre staff).

Results:

Table 2 analysis focused on facet joint violations in a sample of 150 participants with possibility of 300 SFJ violations. Among these, 249 cases were found to have Grade 0 violations, indicating no significant breach, while 51 cases were found to have Grade 1 violations, signifying mild breach without extensive damage. Grade 2 violations, indicating severe breach, were not observed in this sample. In terms of the overall grade of breach across 696 pedicle screws placed with robotic assistance, the majority (88.79%) were Grade 0, indicating no breach, followed by 9.48% classified as Grade 1 breaches, which indicate minor violations, and 1.7% categorized as Grade 2 breaches, reflecting more substantial damage. No cases were recorded under Grade 3 breaches in our dataset.

Regarding the specific types of breaches observed, medial breaches accounted for 5.6% of the total cases, with 27 cases categorized as Grade 1 and 12 cases as Grade 2 medial breaches. Conversely, lateral breaches also accounted for 5.6% of cases in Table 2, with 33 cases classified as Grade 1 and 6 cases as Grade 2 lateral breaches. Notably, no Grade 3 breaches were identified in either medial or lateral categories.

Table 2: Tabulates rate of superior facet joint violation and pedicle breach including medial and lateral breach

Table 3: Compares radiation exposure in milli sievert among patient and health care staff in robotic TLIF

Coming to radiation exposure, in Table 3 radiation exposure is very low for the health care staff i.e., surgeons and operation theatre staff and this value shows clear statistical significance p value 0.0001 (P value < 0.05).

Abbreviations: mSv-millisievert, SD-Standard deviation, PO Preoperative, IOIntra Operative

¹Student t test

Discussion

Pedicle screw fixation is a common technique in many spine surgeries and is crucial for conserving the mechanical stability of the spine. With traditional free-hand pedicle screw fixation, the dissatisfaction rates were 10% -20%, but with C-arm-guided pedicle screw fixation, they were 5% -10%.6,7 The success of spinal fusion depends on pedicle screw fixation. Therefore, to avoid associated difficulties, spine surgeons are always on watch for precise pedicle screw insertion. The robot can also be helpful when high-accuracy screw re-insertion is needed during revision surgery or when the pedicle is difficult to identify in the C-arm. In contemporary spine surgery, robot-assisted spine surgery—a less invasive procedure for pedicle screw fixation—has garnered a lot of interest.

In broad terms, robotic spine surgery can offer three-dimensional images while removing the possibility of human error—such as tremors and fatigue—that might arise during traditional open spine surgeries. Furthermore, real-time navigation and imaging technologies may be employed to raise patient safety, decrease problems, and improve accuracy. According to earlier studies, robot-assisted pedicle screw placement has a high accuracy rate, ranging from 95%-98%.8,9 In our analysis, the accuracy was 98.27% (684/696), which is comparable to earlier findings. The rate of SFJ violation in the robotic group in our analysis was found to be 17%, which is nearly identical to the incidence of violation in Zhang et al.'s previous study.10 The reason for facet joint violation in the robotic group is that, to align the rod, sometimes we purposefully placed the screws medially. This approach makes rod alignment easier, avoids multiple skin incisions and allows decompression and cage insertion to be done through the same incision.

Benefits of robotic spine surgery include increased accuracy, quicker recovery, shorter hospital stays, fewer complications, and revision spine surgeries. In summary, robotic spine surgery has achieved significant advancement and shown promise in the insertion of pedicle screws by increasing the precision of screw positioning. The two most important advancements of robotics in spine surgery so far have been lowering intraoperative radiation exposure and improving procedural consistency across surgeons with varying degrees of training and experience.