Application of 3D visualization virtual surgery system in percutaneous transforaminal endoscopic discectomy

Abstract

Background

Percutaneous transforaminal endoscopic discectomy (PTED) is an effective minimally invasive technique for treating lumbar disc herniation (LDH). However, precise channel establishment remains challenging. A three-dimensional visualization virtual surgery system (3DVVSS) is increasingly used in specific surgeries, yet its value in PTED remains uncertain.

Objective

To investigate the application of a 3DVVSS combined with a self-made intervertebral foramen positioning puncture device (IFPPD) in PTED for the treatment of LDH.

Methods

This study enrolled 120 LDH patients who underwent PTED between January 2021 and February 2022. Patients were randomly assigned to 3DVVSS combined with the IFPPD group (V group), and the traditional freehand methods group (T group). Hospitalization days, number of puncture attempts, fluoroscopy time, operation time, visual analog scale (VAS), Oswestry disability index (ODI), and complications were analyzed.

Results

All patients completed follow-up without serious complications. Hospitalization days between the two groups were comparable (p > 0.05). However, the V group showed statistically significant advantages over the T group in puncture time, number of puncture attempts, fluoroscopy times, and operation time (p < 0.05). All patients exhibited significant improvements in VAS and ODI compared to those of preoperation (p < 0.05). Still, there was no significant difference in VAS and ODI between T and V groups (p > 0.05).

Conclusion

3DVVSS combined with IFPPD can significantly improve the successful puncture rate, and reduce the operation time and the fluoroscopy times, indicating its great potential in future clinical applications.

Keywords

percutaneous endoscopic surgery foraminoplasty transforaminal decompression lumbar disc herniation fluoroscopy three-dimensional visualization minimally invasive

1 Introduction

Percutaneous total endoscopic spinal surgery has evolved into a standard minimally invasive surgical technique in recent years. It offers effective treatment for various types of lumbar disc herniation (LDH) and lumbar spinal stenosis,^1–7 with a nerve decompression effect comparable to traditional open surgery.^8–10 This approach involves direct access to the intervertebral disc lesion through a small cannula, significantly reducing trauma to surrounding tissues. As a result, patients experience reduced postoperative chronic back pain, lower risk of iatrogenic injury, faster recovery, require only local anesthesia, and avoid the contraindications and complications associated with general anesthesia. Percutaneous total endoscopic surgery for LDH primarily involves two approaches: the lateral and posterior approaches. The lateral approach, known as percutaneous transforaminal endoscopic discectomy (PTED), is widely used due to its versatility. The posterior approach is primarily employed for LDH cases unsuitable for the lateral approach.

The biggest disadvantage of endoscopy is the steep learning curve. It has been reported in the literature^11–13 that 30 to 40 patients need to be performed to master this operation. There are many reasons for the steep learning curve, and channel establishment is one of the main reasons. In addition, it is time-consuming for beginners. The early operation time may be as long as several hours, which is a challenge for both doctors and patients, but it only takes tens of minutes in skilled cases. Especially for the transforaminal approach, establishing an ideal channel is critical for beginners, which determines whether the operation can be carried out smoothly and the effect of the operation. If the channel is not established well, the decompression may not be complete or even the herniated intervertebral disc cannot be found. Therefore, to establish an ideal channel, repeated puncture and fluoroscopy are required, which wastes a lot of time and increases the pain of the patient. To establish the ideal channel more accurately and quickly, at present, there are literature reports on the use of mixed reality technology, robot navigation technology, 3D electromagnetic navigation technology, etc.^14–16 These technologies have to some extent improved the effectiveness of channel establishment, but these devices are expensive and require high technical requirements, making it difficult to popularize them in a short period. At present, there is no literature report using this method to establish channels. Therefore, this study aimed to investigate the application of a three-dimensional visualization virtual surgery system (3DVVSS) combined with a self-made intervertebral foramen positioning puncture device (IFPPD) in PTED for the treatment of LDH.

Three-dimensional (3D) visualisation involves the use of computer processing techniques for feature extraction and 3D reconstruction of CT images. It is a tool for displaying, describing and interpreting three-dimensional anatomical and morphological features of organs, thus providing an intuitive, three-dimensional and accurate approach to clinical decision-making. It plays an increasingly important role in the diagnosis and management of many diseases. In the last decade, the use of 3D models combined with hydrodynamic analyses has emerged as a novel non-invasive method for endoscopic discectomy. We present here research advances, workflows, current status, challenges, opportunities of 3D visualisation and its ability to improve clinical decision-making and highlight its utility for patients with PTED disease.

2 Materials and methods

2.1 Inclusion and exclusion criteria

This study was approved by the Ethics Committee of The Affiliated Bozhou Hospital of Anhui Medical University [approval NO: (BY) 2020-0018]. The patients were informed in detail before the operation and signed the informed consent. Inclusion criteria: (1) Age of 18 years or older, with ineffective response to three months of regular conservative treatment; (2) Single-segment, unilateral symptoms, with clinical manifestations concordant with MRI and CT examinations; (3) Type of intervertebral disc herniation classified as paracentral; (4) No serious underlying disease, able to tolerate PTED. Exclusion criteria: (1) previous history of lumbar surgery at the same segment; (2) lumbar instability; (3) central and extreme lateral LDH with severe proximal or distal intervertebral disc prolapse; (4) L5/S1 segment with a high iliac crest or hypertrophy of the L5 transverse process that affects the channel establishment; (5) recent active infection of the spine; (6) follow-up data is incomplete; (7) unable to communicate normally.

2.2 General information and grouping

This prospective study enrolled 120 patients with LDH in the spine surgery department of our hospital between January 2021 and February 2022, and the channel establishment method was selected by the random number table method. 60 cases were established with 3DVVSS combined with IFPPD (V group), and 60 cases were established with traditional freehand methods (T group). After the channel establishment of the two groups, Transforaminal Endoscopic Surgical System (TESSYS) technology was used to complete discectomy and nerve root decompression. The operation channel was established by the same doctor, and the decompression process was performed by the same senior doctor. The general data of the two groups were comparable (p > 0.05) (Table 1).

Table 1.
General baseline data of V group and T group.

Item V group T group p

Sex (case, male: female) 29:31 26:34 0.583

Age[( $\bar{x}$ ± s), y] 52.6 ± 11.6 52.8 ± 12.3 0.945

BMI[( $\bar{x}$ ± s), kg/m²] 23.11 ± 1.87 250 ± 2.19 0.307

Segment (L4/5:L5/S1, n) 37:23 41:19 0.444

Follow-up [( $\bar{x}$ ± s), M] 10.86 ± 1.87 10.63 ± 1.80 0.488

Item	V group	T group	p
Sex (case, male: female)	29:31	26:34	0.583
Age[( $\bar{x}$ ± s), y]	52.6 ± 11.6	52.8 ± 12.3	0.945
BMI[( $\bar{x}$ ± s), kg/m²]	23.11 ± 1.87	250 ± 2.19	0.307
Segment (L4/5:L5/S1, n)	37:23	41:19	0.444
Follow-up [( $\bar{x}$ ± s), M]	10.86 ± 1.87	10.63 ± 1.80	0.488

2.3 Preoperative planning and surgical equipment

Before the operation, the patient should complete the lumbar anteroposterior and lateral radiographs, hyperextension and flexion radiographs, plain CT scan, and 3D reconstruction and MRI of the lumbar vertebral body and accessories. In the V group, the prone position was adopted during the CT examination (the prone position pad used was the same as that in the operation), and the body surface positioning marks were made.

Visual reconstruction of the lumbar spine using human 3DVVSS (China). During the operation, the Joinmax transforaminal lens and radiofrequency system (Germany) were used.

Description of 3D visualization: 3D visualization uses CT data (Dicom format) and a three-dimensional visual medical diagnostic image processing system to process the data. The processed three-dimensional images can be rendered in different colors, arbitrarily rotated, scaled, split, and adjusted for transparency and other operations. The relationships between bone tissue, organs, blood vessels, nerves, and other tissues are visible.

Introduction to self-made IFPPD: (IFPPD) was developed to enhance precision and control during percutaneous puncture procedures. Composition (Figure 1A, B) includes 1-Fixer, 2-Connecting Rod, 3-Protractor, 4-Gauge Needle, 5-Guide and 6, 7, 8 three joints, providing a robust framework for the procedure. The fixer stabilizes the device, ensuring a fixed position, while the connecting rod links various components, maintaining structural integrity. The protractor allows precise angle adjustments for needle insertion. The guide features a “cross” shape on the entry side and a small circular opening on the exit side (Figure 1C), facilitating accurate needle placement. The joints (6, 7, and 8) can rotate 360°, with joints 6 and 7 capable of sliding up and down to adjust the height. Constructed from medical-grade stainless steel or high-strength polymer, the device ensures durability and sterilizability. The needle direction can be fine-tuned in eight different directions (Figure 1D), enhancing targeting accuracy. During the procedure, the close proximity of the needle exit to the skin entry point allows for real-time fine-tuning of the puncture target (Figure 1E, F, G). The device's ability to fix angles and directions without affecting the intraoperative perspective, combined with its rotational and height-adjustable joints, offers flexibility and precision in various percutaneous procedures.

Figure 1.

Self-made intervertebral foramen positioning puncture device (A) schematic diagram; (B) physical picture; (C) guide; (D) puncture needle punctures along the guide during operation; (E∼G) adjust the puncture direction.

2.4 Surgical method of v group

To reduce errors caused by body position changes, the preoperative lumbar spine CT examination was performed in the same position as the surgery (Figure 2A), so that the CT data obtained are more accurate. Metal positioning markers were placed on the body surface of the patient's lower back before CT (Figure 2B), and then the CT data was used for 3D visual reconstruction to completely reconstruct the body surface markers. Use a marker pen to mark the skin position corresponding to the metal object on the patient's body for intraoperative reference. A CT scan covering the entire skin area of the patient's back should be performed, and plain CT scan data of the lumbar spine in Dicom 3.0 format should be obtained. The plain CT scan data of the lumbar spine were then imported into a 3D visualized medical diagnostic image processing system to reconstruct a 3D visual model of the lumbar spine, including nerves, dura mater, skin, body surface markers, muscles, intervertebral discs, bone tissue, etc. (Figure 2C). Different tissues were marked with various colors.

Figure 2.

Relevant pictures during the operation (A) CT position; (B) metal positioning marks inside the yellow circle on the lower back body surface; (C) Visual reconstruction results, where the color of the virtual channel changes in the green circle is the position of the skin needle entry point, The reconstructed body surface markers are inside the blue circle; (D) rotate the image to observe the relationship between the pipeline and the surrounding tissue; (E) measure the puncture abduction angle; (F) determine the puncture direction; (G) mark the puncture parameters before operation, and the red circle is the position of the needle entry point, the green arrow is the puncture direction; (H) intraoperative puncture; (I) articular process anesthesia; (J) self-made perspective angle measuring device.

A virtual operative cannula with a 7.5 mm diameter and a virtual puncture needle were built to establish a preoperative simulation channel, and the virtual working cannula and puncture needle were adjusted to achieve the ideal position (Figure 2C). 360-degree rotation images were utilized to examine the relationship between the operative cannula and the emerging nerve root, facet joint, and intervertebral disc (Figure 2D). Using the skin surface marker as a reference position, the skin entry point for the needle during the operation can be determined, This is identified as the point of intersection between the virtual puncture needle and the skin surface (highlighted inside the green circle in Figure 2C). The angle of abduction of the virtual puncture needle from the sagittal plane was measured, representing the abduction angle of the needle during the operation (Figure 2E). According to the projection of the simulated puncture needle on the body surface and the position of the markers on the skin surface (Figure 2F), the intraoperative puncture direction was calculated. Before the operation, mark the position of the needle entry point, puncture abduction angle, and puncture direction on the patient's skin surface (Figure 2G) for direct puncture during the operation.

Prone position, local skin anesthesia with lidocaine injection, the stabilizer is securely affixed to the operating table adjacent to the surgeon's dominant hand. An elastic threaded cap is employed to finely tune the heights of joints 6 and 7, ensuring that the needle probe is correctly positioned directly above the patient's designated puncture site. Following this, joint 8 is meticulously aligned to ensure that both the guide and the marked puncture site on the superficial skin match the pre-planned puncture angle, thereby facilitating precise surgical execution. 18G puncture needle slowly punctures the intervertebral foramen from the center of the guide along the preoperatively planned puncture parameters (Figure 2H), the puncture needle needs to be parallel to the scale needle, and the needle insertion position is determined by fluoroscopy. In the anteroposterior projection, the optimal puncture position is identified at the intersection of the line connecting the upper endplate of the lower vertebral body and the inner edge of the pedicle. In the lateral view, the target for puncture is identified at the intersection of the posterior border of the lower vertebral body and the superior endplate of the lower vertebral body.¹⁷ If the position is not good, use the “criss-cross” type guide to fine-tune. After the position is satisfactory, inject anesthesia for intervertebral foraminal area anesthesia. IFPPD was withdrawn after wire replacement. The 18G puncture needle is advanced along the guide wire direction for puncture. Ensure to puncture slightly dorsally to target the superior articular process (SAP) of the lower vertebral body. You can feel the bony obstruction. This is the SAP. Inject anesthesia for SAP anesthesia (Figure 2I). Finally, dorsal fascia anesthesia was performed. After the channel is established, the intervertebral discectomy and nerve root decompression are completed according to the standard TESSYS technique.

2.5 Surgical methods in the T group

The design of the puncture path and channel establishment in the T group depended on the experience of the surgeon, the patient's body dimensions, preoperative CT, and MRI scans of the lumbar spine, and intraoperative fluoroscopy. The intervertebral space and puncture angle were determined using a self-made perspective angle measuring device (Figure 2J, patent number: ZL 2021 3 0855068.9). After the channel is established, the remaining steps are the same as the V group.

2.6 Postoperative treatment and follow-up

Postoperatively, patients were routinely treated with nerve dehydration and other treatments. Strictly stay in bed for 6 h after the operation, patients can walk out of bed wearing a waistband within 1 month, avoid bending over and sitting for a long time, and avoid physical labor within 3 months. Outpatient follow-up was conducted 3 and 6 months after the operation, and lumbar spine CT and MRI were completed during the follow-up.

2.7 Observation indicators

Pain visual analog scale (VAS). Oswestry disability index (ODI), other evaluation indicators include hospitalization days, number of puncture attempts, puncture time, fluoroscopy times, and complications.

2.8 Statistical analysis

Statistical analysis was conducted using the Statistical Package for the Social Sciences (SPSS) version 25.0 (IBM Corporation, Armonk, NY, USA). The measurement data satisfying the normal distribution were represented by means. Within-group comparisons before and after were conducted using paired t-tests or repeated measures analysis of variance (ANOVA), and Between-group comparisons were conducted using two independent sample t-tests. Paired t-tests are applicable to paired pre- and post-intervention comparisons of the same group of study subjects, such as preoperative and postoperative comparisons of the same group of patients. Whereas, the repeated measures ANOVA, which functions similarly to the paired t-test, is designed to compare whether there is a difference in the means obtained after multiple measurements (different time points, different experimental conditions, etc.) on the same group of individuals. Two comparisons were conducted using the Wilcoxon signed-rank sum test. The Wilcoxon signed-rank sum test is commonly used to compare the median of the difference of paired samples to zero, thus testing whether there is a difference between the medians of two sums from a pair of related samples. Categorical data were presented as frequency (%) and compared between groups using the Chi-square test. A two-sided test was used with α = 0.05.

3 Results

3.1 General results

All 120 patients completed the operation without complications. The hospitalization days between the two groups were comparable (t = −0.173, p = 0.863). V group was significantly better than the T group in puncture time, the number of puncture attempts, fluoroscopy times, and operation time (all p < 0.05) (Table 2). The number of puncture attempts in the T group was significantly higher than those of the V group (6 vs 3, p < 0.05).

Table 2.
Comparison of general results between the two groups ( $\bar{x}$ ± s).

Group HD(day) PT(min) Number of puncture attempts (times) FTS(times) OT(min)

V group 4.65 ± 0.81 13.28 ± 3.88 3.93 ± 1.99 8.38 ± 3.38 88.83 ± 12.63

T group 4.61 ± 1.24 18.41 ± 3.69 6.81 ± 2.61 14.33 ± 4.72 96.25 ± 14.97

Statistic t = −0.173 t = −6.522 t = −6.777 t = −7.925 t = −2.932

p value p = 0.863 p < 0.001 p < 0.001 p < 0.001 p = 0.004

Group	HD(day)	PT(min)	Number of puncture attempts (times)	FTS(times)	OT(min)
V group	4.65 ± 0.81	13.28 ± 3.88	3.93 ± 1.99	8.38 ± 3.38	88.83 ± 12.63
T group	4.61 ± 1.24	18.41 ± 3.69	6.81 ± 2.61	14.33 ± 4.72	96.25 ± 14.97
Statistic	t = −0.173	t = −6.522	t = −6.777	t = −7.925	t = −2.932
p value	p = 0.863	p < 0.001	p < 0.001	p < 0.001	p = 0.004

HD, hospitalization days; PT, puncture time; FTS, Fluoroscopy times; OT, operation time.

3.2 VAS scoring

The VAS scores decreased significantly in the V and T groups from preoperation to 6 months after operation (p < 0.05). The VAS scores were comparable between the two groups 1 day after the operation, 6 months after the operation, and before the operation (p > 0.05) (Table 3).

Table 3.
Comparison of VAS scores between the two groups [( $\bar{x}$ ± s), score].

Group Pre. 1 day Pos. 6 months Pos. Statistic(F) p-value

V group 7.63 ± 0.84 2.90 ± 1.29 1.08 ± 0.74 2244.141 p < 0.001

T group 7.51 ± 0.89 2.41 ± 1.53 1.16 ± 0.69

Statistic t = 0.736 t = 1.864 t = −0.635

p value p = 0.463 p = 0.065 p = 0.526

Group	Pre.	1 day Pos.	6 months Pos.	Statistic(F)	p-value
V group	7.63 ± 0.84	2.90 ± 1.29	1.08 ± 0.74	2244.141	p < 0.001
T group	7.51 ± 0.89	2.41 ± 1.53	1.16 ± 0.69
Statistic	t = 0.736	t = 1.864	t = −0.635
p value	p = 0.463	p = 0.065	p = 0.526

Pre. = preoperation; Pos. = postoperation.

3.3 ODI

The ODI scores decreased significantly in the V and T groups from preoperation to 6 months after operation (p < 0.05). The ODI scores were comparable between the two groups 1 day after the operation, 6 months after the operation, and before the operation (p > 0.05) (Table 4).

Table 4.
Comparison of ODI scores between the two groups [( $\bar{x}$ ± s), %].

Group Pre. 1 day Pos. 6 months Pos. Statistic(F) p value

V group 67.32 ± 6.83 22.19 ± 7.00 11.79 ± 2.00 4976.718 p < 0.001

T group 65.91 ± 6.67 20.98 ± 6.12 12.42 ± 2.35

Statistic t = 1.139 t = 1.009 t = −1.583

p value p = 0.257 p = 0.315 p = 0.116

Group	Pre.	1 day Pos.	6 months Pos.	Statistic(F)	p value
V group	67.32 ± 6.83	22.19 ± 7.00	11.79 ± 2.00	4976.718	p < 0.001
T group	65.91 ± 6.67	20.98 ± 6.12	12.42 ± 2.35
Statistic	t = 1.139	t = 1.009	t = −1.583
p value	p = 0.257	p = 0.315	p = 0.116

Pre. = preoperation; Pos. = postoperation.

3.4 Typical patient

A 42-year-old male was diagnosed with L5/S1 intervertebral disc herniation. Three-dimensional visual reconstruction of the lumbar spine was performed before the operation, and a channel was established under the guidance of self-made IFPPD, and then a PTED operation was performed. The patient recovered satisfactorily after surgery (Figure 3).

Figure 3.

(A) typical patient, male, 42 years old, with L5/S1 intervertebral disc herniation A, (B) lumbar anteroposterior and lateral radiographs; (C, D, E) preoperative lumbar spine CT and MRI showed L5/S1 intervertebral disc herniation, partial protrusion on the left side without calcification; (F) 3D visualization reconstruction results; (G) the puncture parameters were marked on the patient's body surface before surgery, the red circle is the position of the needle entry point, the red arrow is the puncture direction, and the abduction angle of the puncture is 53 degrees; (H) the puncture was performed according to the preoperatively designed puncture parameters; (I, J) the position of the puncture needle in anteroposterior and lateral perspectives; (K, L) the position of the anteroposterior and lateral perspectives after the working channel was placed was satisfactory; (M) the ventral and dorsal sides of the sacral 1 nerve root thorough decompression on both sides; (N) removal of superior articular process and intervertebral disc of sacrum 1; (O) one needle sutured to the postoperative wound; (P, Q) MRI reexamination half a year after operation showed that the prominent nucleus pulposus was completely removed, and the intervertebral foramina was completely decompressed.

4 Discussion

Accurate puncture is a crucial step in the PTED technique and a key factor for the success of the procedure. It helps minimize the number of puncture attempts, puncture-related injuries, and radiation exposure. This study demonstrates that the combination of 3DVVSS with a self-designed IFPPD can enhance puncture accuracy, reduce fluoroscopy time, and shorten the channel establishment duration. The 3DVVSS combined with the skin surface positioning marking method can accurately transfer the ideal simulated puncture parameters to the patient, and the needle entry points, puncture angle, and direction can be marked on the patient's skin before surgery.

3DVVSS is established by simulating channels from a three-dimensional perspective, which is more accurate and reliable than two-dimensional CT and MRI. This system can reconstruct the nerve root, and the preoperative simulation channel can avoid the emerging nerve root, reducing the risk of nerve root puncture injuries. For patients with high iliac crest at the L5/S1 level or wide transverse processes of L5, 3DVVSS reconstruction of the lumbar spine and simulated cannulation can help clarify the bony obstruction, determining the feasibility of successful cannulation, and assist in selecting the appropriate surgical approach. CT examination and operation are performed in the same body position, and the use of the same prone position cushion helps reduce errors. The guide's needle entry side is designed as a “cross” type, allowing fine-tuning of the needle entry direction along 8 different angles. This feature enables precise adjustment of the puncture target by adjusting the needle insertion direction. Additionally, the self-made IFPPD is simple in design and easy to use, making it suitable for widespread adoption. The 3D visualizations of the lumbar spine are generated by a specialized company, requiring only CT data from doctors.

According to the surgical procedure, several factors affect the learning curve of PTED: (1) Transforaminal puncture to establish a channel to prevent exiting nerve root damage or irritation; (2) Effective nerve decompression under direct vision of the endoscope; (3) Effective management of intraoperative complications, such as bleeding, dural tears, and intraoperative pain. The initial step is to safely perform a posterolateral puncture through the neural foramen while avoiding injury to the exiting nerve root. The neural foramen at the L5/S1 level is typically narrow, increasing the risk of injury to the exiting nerve root during the insertion of the operative cannula. To prevent nerve injury, the landing site should be positioned dorsally and caudally to the neural foramen, near the site of the epidural herniated disc to ensure more effective decompression.

The use of effective positioning methods or navigation before operation can reduce operation time and radiation exposure,^18–20 we use 3DVVSS to determine the best puncture channel before operation, which can avoid exiting nerve root, and at the same time achieve the purpose of target puncture, combined with the use of self-made IFPPD, the results prove that this method can reduce the number of punctures and channel establishment time, significantly reduce radiation exposure, and shorten the learning curve. The second critical step is that surgeons must be proficient in identifying tissue layers and operating the equipment. It is essential to differentiate between anatomical structures, including the dural sac, epidural space, herniated disc, posterior longitudinal ligament, and intervertebral disc. The release and decompression of nerve root adhesions are critical for success. Finally, bleeding, dural tears, adhesions, and pain encountered during surgery should be managed appropriately. At times, patients may experience severe pain or discomfort due to various reasons. Therefore, appropriate pain management measures should be administered during the procedure. Ao et al.²¹ demonstrated in their study that the utilization of the O-arm-assisted navigation system can enhance the learning curve for percutaneous endoscopic lumbar discectomy. Artificial intelligence (AI) is becoming more and more widely used in the medical field and is developing very rapidly. It involves many fields of medicine.²² Its application in minimally invasive spine surgery is very meaningful, but it is still in the exploratory stage and there are still many problems that need to be solved. I believe that shortly AI will make breakthrough progress in minimally invasive spine surgery. This study used 3DVVSS combined with the self-made IFPPD method to establish the channel, which is superior to the traditional method in terms of channel establishment time, number of puncture attempts, and fluoroscopy times. This approach shortens the learning curve somewhat.

Personal experience: (1) The trephine is used for foraminoplasty. Trephine slip is easy to occur at the beginning of bone grinding, resulting in an improper position. It is recommended to use the trephine counterclockwise when the bone is first ground, and the assistant fixes the protective sleeve. Rotate the trephine clockwise after entering a certain depth, which can prevent the trephine from slipping. (2) The position of the first foraminoplasty is very important, but for beginners who lack experience, it is easy to have an unsatisfactory position for the first foraminoplasty and often needs to be re-formed or even repeated. It is recommended that when the trephine enters a small amount of bone, it should be examined once to confirm whether the position of the trephine is satisfactory. If not, the position should be adjusted appropriately. This will reduce the bleeding of bone tissue, reduce the difficulty of the operation, and avoid removing too much bone tissue. (3) During the insertion of the expansion tube, if the patient complains of symptoms in the legs, consider that the exiting nerve root was squeezed or irritated, and do not insert the expansion tube forcibly. It is advisable to adjust the puncture target caudally to avoid injury to the exiting nerve root. (4) For obese patients, the entire lower back skin should be included in the lumbar spine CT scan.

A limitation of this study is its single-center design with a small sample size and short follow-up duration. In the future, we intend to conduct multicenter studies with long-term follow-up. During the procedure, the patient's positioning is crucial, as the abduction angle of the puncture is significantly influenced by the patient's position. During the procedure, it is important to ensure that the plane containing the patient's spinous process is perpendicular to the ground plane. Additionally, the large and heavy fixed frame is difficult to transport and utilize. It can be replaced with a more compact version and directly fixed onto the operating table.

5 Conclusion

In conclusion, the 3DVVSS combined with a homemade IFPPD in percutaneous endoscopic lumbar disc herniation (LDH) treatment significantly reduced the number of punctures, fluoroscopy time, puncture duration, and overall operative time, which suggests a great potential for future clinical applications. By reducing these operational metrics, not only is the efficiency and safety of the procedure improved, but also the patient's discomfort and radiation exposure during the procedure is reduced. The application of this technology is expected to optimize the surgical process, enhance treatment outcomes and provide physicians with more precise operational guidance. These advantages make 3DVVSS combined with IFPPD promising in clinical practice and worthy of further promotion and research.

Footnotes

Ethical compliance

This study was approved by the Ethics Committee of The Affiliated Bozhou Hospital of Anhui Medical University, approval number: (BY) 2020-0018. Signed written informed consent were obtained from the patients and/or guardians.

Consent for publication

Not applicable.

Author contributions

CG and MZ designed the study and performed the experiments, JW and ZS collected the data, XL and YN analyzed the data, and CG and MZ prepared the manuscript. All authors read and approved the final manuscript.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Bozhou Health Scientific Research Project (bzwj2023b002). The Key research and development projects in Anhui Province (202104j07020053). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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