A comparative study of robot-assisted and traditional surgeries in the treatment of thoracolumbar fractures based on 1-year follow-up observation

Abstract

BACKGROUND:

There are conflicting results for robot-assisted (RA) pedicle screw fixation compared with freehand (FH) pedicle screw fixation.

OBJECTIVE:

This study was designed to retrospectively compare the accuracy and efficacy of RA percutaneous pedicle screw fixation and traditional freehand FH pedicle screw fixation in the treatment of thoracolumbar fractures.

METHODS:

A total of 26 cases were assigned to the RA group, and 24 cases were assigned to the FH group. The operation time, bleeding volume, and visual analog scale (VAS) score 1 day after the operation, and the anterior/posterior (A/P) vertebral height ratio of the injured vertebrae at 3 days and at internal fixation removal 1 year after the operation were compared between the two groups. Pedicle screw position accuracy was assessed according to Gertzbein criteria.

RESULTS:

The operation times of the RA group and FH group were 138.69 ± 32.67 minutes and 103.67 ± 14.53 minutes, respectively, and the difference was statistically significant. The intraoperative blood loss was 49.23 ± 22.56 ml in the RA group and 78.33 ± 23.90 ml in the FH group, and the difference was statistically significant. There was a significant difference in the A/P vertebral height ratio of the injured vertebrae 3 days after the operation compared with before the operation in both groups (P < 0.05). There was a significant difference in the A/P vertebral height ratio of the injured vertebrae 3 days after the operation compared with that at fixation removal in both groups (P < 0.05).

CONCLUSION:

The application of RA orthopedic treatment for thoracolumbar fractures can achieve good fracture reduction.

Keywords

Orthopedic robot thoracolumbar fractures pedicle screw

1. Introduction

Influenced by spinal physiological curvature, thoracolumbar fractures are the most common spinal fractures and account for about 50% to 60% of fractures [1]. At present, a posterior pedicle screw fixation is the principal method of reconstruction of spinal stability. However, traditional posterior open reduction and internal fixation surgery requires the dissection of the paravertebral muscles, resulting in greater surgical trauma and the possible occurrence of chronic low back pain [2]. Therefore, more and more scholars are using the percutaneous pedicle screw fixation technique or the Wiltse intermuscular approach to prevent excessive injury to paravertebral muscles [3–5]. However, the failure rate of pedicle screw placement can reach 37.5% [6]. This failure rate is influenced by the clinical experience of the surgeon and the individual anatomical variation of patients. Poor pedicle screw placement can lead to decreased pedicle screw strength, poor fracture reduction, cerebrospinal fluid leakage, and critical vascular or nerve injury.

In 2006, SpineAssist^® (Mazor Robotics^®) was the first robot used in spinal surgery to assist pedicle screw placement [7]. With the development of digital navigation technology, various robots, such as ROSA Spine^® (Medtech) and Excelsius GPS^® (Globus Medical), were developed and applied in spinal surgery. Many studies have reported that robot-assisted (RA) percutaneous pedicle screw fixation is safer and more accurate than conventional freehand (FH) pedicle screw fixation [8,9]. However, several studies have revealed conflicting results for RA fixation compared with FH [10–13]. In this paper, we compare the accuracy and safety of Tianji (Beijing Tinavi Medical Technology) orthopedic RA percutaneous pedicle screw fixation with conventional FH pedicle screw fixation in thoracolumbar spinal fractures.

2. Materials and methods

2.1. General information

The inclusion criteria of patients were as follows: single-segment thoracolumbar fracture, patients requiring posterior pedicle screw fixation, and the time from injury to operation not exceeding 2 weeks. The exclusion criteria were multiple vertebral fractures, severe osteoporosis, anterior decompression required for obvious compression of the spinal canal, and patients with severe underlying diseases who might not be able to tolerate the operation. Based on the inclusion and exclusion criteria, patients with thoracolumbar fractures who were treated with RA therapy in our department from January 2019 to January 2020 were included in the RA group (26 cases). Twenty-four patients with thoracolumbar fractures who were treated by intramuscular FH screw placement were included in the traditional operation group.

2.2. Surgical methods

(1) Robot-assisted group

After successful anesthesia, the patient was placed in the prone position, and the empty chest and abdomen were padded. The back operation area was routinely disinfected and draped. An infrared stereo camera was placed on the site near the patient’s head. The orthopedic robot arm was isolated using a sterile protective sleeve membrane. A patient tracer was fixed on the superior spinous process adjacent to the fracture segment (Fig. 1). A C-arm X-ray machine was used to conduct fluoroscopy on the injured vertebrae and the marked points, making sure that ≥5 marked points were within the fluoroscopic field. A Siemens ARCADIS Orbic 3D system was used to scan and obtain three-dimensional (3D) image data of the patients. The automatic registration of 3D image data via the mechanical arm was completed. Pedicle screw planning was completed on the operating computer (Fig. 2), and the mechanical arm was started after checking that it functioned correctly. After the mechanical arm was moved to the screw insertion position autonomously, a skin incision of about 2 cm was made along the direction of the catheter sleeve. The working sleeve was positioned on the bone surface, and six guide pins were placed through the working sleeve. The position was again confirmed by the C-arm X-ray machine (Fig. 3). Reaming and screwing were performed along the guide pin, and the planned pedicle screw was screwed to the corresponding depth along the guide pin. A pre-bent rod was inserted from the long tail groove of the screw to support and lock the long tail of the screw. The C-arm X-ray machine conducted anteroposterior and lateral fluoroscopy (Fig. 4), confirming that the screw position was correct. Finally, the incision was rinsed and sutured.

Fig. 1.

Intraoperative schematic diagram of orthopaedic robot.

Fig. 2.

Computer planning of pedicle screw placement path.

Fig. 3.

Robot-assisted guide pin implantation.

Fig. 4.

Intraoperative fluoroscopy of pedicle screw position and fracture reduction.

(2) Traditional operation group

After successful anesthesia, the patient was placed in the prone position, and the empty chest and abdomen were padded. The back operation area was routinely disinfected and draped. An 8-cm incision was made with the injured vertebra as the center, and the skin and subcutaneous tissues were cut in turn. The lumbar dorsal fascia was cut along both sides of the spinous process, and the facet joints of the injured vertebra and the upper and lower vertebrae were exposed through the space between the multifidus muscle and the longissimus muscle. Using transverse process positioning or herringbone spine positioning, pedicle screws of appropriate length and thickness were placed (measured according to preoperative computed tomography [CT]). The C-arm X-ray machine performed anteroposterior and lateral fluoroscopy to confirm that the screw position was correct. A connecting rod was installed, distraction reduction fixation was performed, and the tail cap was locked. The incision was rinsed, two negative pressure drainage tubes were inserted, and the incision was sutured layer by layer.

2.3. Evaluation indexes

The operation time and the intraoperative blood loss of the two groups were observed and recorded. Visual analog scale (VAS) scores were recorded 1 day after the operation. The anterior/posterior (A/P) vertebral height ratio of the injured vertebrae was evaluated 3 days after the operation and at the time of internal fixation removal. A CT thin-layer scan was performed, and the pedicle screw position accuracy was assessed according to Gertzbein criteria [14], as follows: Grade 0: not penetrating the vertebral arch cortex, Grade 1: piercing the vertebral arch cortex by <2 mm, Grade 2: piercing the vertebral arch cortex by 2–4 mm, and Grade 3: piercing the vertebral arch cortex by >4 mm or the pedicle screw completely piercing the pedicle. The VAS scores were evaluated 3 days after the operation.

2.4. Statistical analysis

The data were statistically analyzed using SPSS 19.0 statistical software. Count data were expressed as relative numbers and compared between the groups using Chi-squared tests. Normally distributed measurement data were expressed as mean ± standard deviation (x ± SD); data between the groups were compared using independent-sample t-tests, and data before and after treatment were compared within one group using paired-sample t-tests. A value of P < 0.05 was considered statistically significant.

3. Results

3.1. General data

A total of 50 patients were included in this study. There were 26 cases in the RA group, aged 58.04 ± 9.15 years. Among these patients, 14 were male and 12 were female. In the FH group, there were 24 cases. Their ages ranged from 53.92 ± 5.48. In this group, 13 were male and 11 were female. There were no statistical differences between the two groups in age, gender, or the A/P vertebral height ratio of the injured vertebrae before operation (P > 0.05, Table 1).

Table 1
Comparison of general data between two groups of patients

Group Number of cases Age Gender (male/female) A/P vertebral height ratio of injured vertebrae (%) VAS

RA group 26 58.04 ± 9.15 14/12 67.35 ± 8.37 7.12 ± 0.77

FH group 24 53.92 ± 5.48 13/11 69.50 ± 9.48 6.96 ± 0.75

t/χ ² 1.91 0.00 −0.85 0.73

p 0.06 0.98 0.40 0.47

Group	Number of cases	Age	Gender (male/female)	A/P vertebral height ratio of injured vertebrae (%)	VAS
RA group	26	58.04 ± 9.15	14/12	67.35 ± 8.37	7.12 ± 0.77
FH group	24	53.92 ± 5.48	13/11	69.50 ± 9.48	6.96 ± 0.75
t/χ ²		1.91	0.00	−0.85	0.73
p		0.06	0.98	0.40	0.47

3.2. Operation condition

Bleeding volume: This was 49.23 ± 22.56 ml in the RA group and 78.33 ± 23.90 ml in the FH group. The difference was statistically significant (t = 4.46, P < 0.05).

Operation time: This was 138.69 ± 32.67 minutes in the RA group and 103.67 ± 14.53 minutes in the FH group. The difference was statistically significant (t = 4.96, P < 0.05).

3.3. Evaluation of reduction of injured vertebrae

Before the operation, the A/P vertebral height ratio of the injured vertebrae was (67.35% ± 8.37%) in the RA group and (69.50% ± 9.48%) in the FH group. The difference was not statistically significant (t = −0.85, P > 0.05). Three days after the operation, the A/P vertebral height ratio of the injured vertebrae was (82.42% ± 9.83%) in the RA group and (80.70% ± 7.89%) in the FH group. At internal fixation removal, the A/P vertebral height ratio of the injured vertebrae was (78.97% ± 10.46%) in the RA group and (78.49% ± 7.58%) in the FH group. The A/P vertebral height ratio of the injured vertebrae after the operation was significantly higher than that before the operation in both groups (P < 0.05). The A/P vertebral height ratio of the injured vertebrae 3 days after the operation was significantly higher than that at internal fixation removal in both groups (P < 0.05). There was no significant difference in the A/P vertebral height ratio of the injured vertebrae between the RA group and the FH group 3 days after the operation (t = 0.68, P > 0.05). There was no significant difference in the A/P vertebral height ratio of the injured vertebrae between the two groups at internal fixation removal (t = 0.19, P > 0.05).

3.4. Screw placement accuracy assessment

The accuracy evaluation results of pedicle screw placement in the two groups according to the Gertzbein standard [14] are shown in Table 2. A total of 300 pedicle screws were placed in patients in the two groups. In the RA group, 156 screws were placed, including 147 screws of grade 0, 6 screws of grade 1, 3 screws of grade 2, and 0 screws of grade 3. The accuracy rate was 94.23%. In the FH group, 144 screws were placed, including 115 screws of grade 0, 19 screws of grade 1, 8 screws of grade 2, and 2 screws of grade 3. The accuracy rate was 79.86%. There was a significant difference in the accuracy of pedicle screw placement between the two groups (χ ² = 13.98, P < 0.05).

Table 2
Comparison of accuracy rate of pedicle screw placement between the two patients

Group Number of placed screws Grade 0 Grade 1 Grade 2 Grade 3 Accuracy rate

RA group 156 147 6 3 0 94.23%

FH group 144 115 19 8 2 79.86%

Group	Number of placed screws	Grade 0	Grade 1	Grade 2	Grade 3	Accuracy rate
RA group	156	147	6	3	0	94.23%
FH group	144	115	19	8	2	79.86%

3.5. Visual analog score and postoperative complications

There was no significant difference in VAS scores before the operation between the two groups (P > 0.05). One day after the operation, the VAS score was 3.15 ± 0.75 in the RA group and 4.13 ± 0.80 in the FH group. The difference between the two groups was statistically significant (t = −4.34, P < 0.05). There was no nerve injury caused by pedicle screw placement in either group after the operation. There were two cases of urinary tract infection in the RA group, two cases of urinary tract infection in the FH group, and there were two cases of deep venous thrombosis in the FH group.

4. Discussion

At present, posterior pedicle screw fixation is the main method used to treat thoracolumbar fractures. However, traditional posterior surgery requires the extensive freeing of the paravertebral muscles along the spinous process and vertebral lamina until the articular process is exposed. The surgical trauma is significant, and it often leads to chronic lower back pain after the operation. Pedicle screw fixation via the intramuscular approach and percutaneous pedicle screw fixation conform to the concept of minimally invasive spine surgery. This process tries to prevent peeling and pulling injuries to the multifidus muscle and reduces the denervation of the multifidus muscle as far as possible. Therefore, they are the two principal methods for the minimally invasive treatment of thoracolumbar fractures [15]. There is little difference between intramuscular approach screw fixation and traditional posterior median approach screw fixation, and they are easy to master. However, compared with them, percutaneous pedicle screw fixation has higher requirements for the surgeon, and the amount of radiation is larger [16]. According to the statistics, even with open screw fixation, the screw adjustment rate is still up to 10%, and the adjustment of the screw will also greatly reduce the screw-holding force [17]. Moreover, the thickness and length of the screws in traditional surgery mainly depend on a rough estimation of intraoperative fluoroscopy images, which cannot achieve maximum optimization.

In recent years, with the development of digital navigation technology, orthopedic robot technology has been successfully applied in clinical practice. The Tianji orthopedic robot reconstructs 3D images according to the CT scanning of patients during operations and pre-plans the screw path, thickness, and length to correctly achieve individualized screw design. Theoretically, the screw fixation error can be reduced to a sub-millimeter level. One scholar considers that RA screw fixation can theoretically optimize the screw position, i.e., the screw position is safe, the length is the longest, the thread is the thickest, and the holding force is the strongest. This is inevitably conducive to reducing fractured vertebral bodies and maintaining vertebral body height after reduction [18]. This study revealed that both RA and traditional surgery could effectively reduce thoracolumbar fractures. The blood loss in the RA group was significantly less than in the FH group, and the A/P vertebral height ratio of the injured vertebrae after the operation was significantly higher than before the operation in both groups. This is consistent with the results reported in previous studies [19–21]. The VAS score of the RA group was significantly lower than that of the FH group on the first day after operation. Therefore, patients in the RA group can better collaborate on early functional exercises, which are conducive to reducing postoperative urinary tract infection, lower limb venous thrombosis, and other complications.

Previous studies have revealed that the accuracy of pedicle screw placement assisted by different robot systems was much higher than that of traditional FH screw fixation by avoiding screw loosening caused by intraoperative screw adjustment or postoperative complications related to internal fixation [22,23]. In the present study, the accuracy rate of pedicle screw placement was 94.23% in the RA group and 79.86% in the FH group. This is consistent with what has been reported in previous literature. However, there is a certain failure rate for RA pedicle screw fixation. We consider that it is mainly related to the following factors: (1) The pedicle screw itself is thin due to the variation of the pedicle screw, so it is recommended to select the appropriate thickness screw during planning. (2) After general anesthesia in the prone position, respiratory movement leads to vertebral body movement, which increases robot positioning and operator error. Therefore, it is necessary to remind anesthesiologists to control tidal volume. (3) In cases of unreasonable planning before screw fixation, the needle entry point of the Kirschner wire is located at the tip of the bony protrusion. When the electric drill starts, it is easy for the Kirschner wire to slip and shift. This should be prevented as much as possible during planning.

This study also revealed that the operation time of the RA group was significantly longer than that of the FH group. This is inconsistent with the results reported in some literature [21]. Based on the experience of Hao et al. [24], it is believed that the RA treatment of thoracolumbar fractures generally requires about 10 patients to complete the learning curve. Since January 2019, our department has introduced the latest generation of Tianji orthopedic robots and used robots to assist pedicle screw fixation for the first time. The influence of the surgeon’s operating experience and proficiency led to a relatively long operation time for patients in the early stage.

5. Conclusion

The application of RA orthopedic treatment for thoracolumbar fractures can achieve a good fracture reduction effect. Compared with traditional surgery, an orthopedic surgery robot has the advantages of low trauma, high precision, good repeatability, and fatigue resistance. With the continuous accumulation of experience and the regular updating of hardware equipment and auxiliary software, orthopedic surgical robots will be routinely employed in clinical practice.

Footnotes

Acknowledgements

The authors would like to thank the hard and dedicated work of all staff that implemented the intervention and evaluation components of the study.

Ethics statement

The study was conducted with approval from the Ethics Committee of the Second Affiliated Hospital of Jiaxing University (No. JXEY-LWSC099). The study was conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all participants.

Competing interests

The authors declare that they have no competing interests.

Funding

The study was supported by the Medical and Health Science Platform Project of Zhejiang Province (No. 2020KY957).

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A comparative study of robot-assisted and traditional surgeries in the treatment of thoracolumbar fractures based on 1-year follow-up observation

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSION:

Keywords

1. Introduction

2. Materials and methods

2.1. General information

2.2. Surgical methods

2.4. Statistical analysis

3. Results

3.1. General data

3.3. Evaluation of reduction of injured vertebrae

3.4. Screw placement accuracy assessment

Table 2 Comparison of accuracy rate of pedicle screw placement between the two patients Group Number of placed screws Grade 0 Grade 1 Grade 2 Grade 3 Accuracy rate RA group 156 147 6 3 0 94.23% FH group 144 115 19 8 2 79.86%

4. Discussion

5. Conclusion

Footnotes

Acknowledgements

Ethics statement

Competing interests

Funding

References

Table 2
Comparison of accuracy rate of pedicle screw placement between the two patients

Group Number of placed screws Grade 0 Grade 1 Grade 2 Grade 3 Accuracy rate

RA group 156 147 6 3 0 94.23%

FH group 144 115 19 8 2 79.86%