Clinical Evaluation of Unilateral Vertebroplasty for OVCF.

Objective: To investigate the clinical evaluation of unilateral vertebroplasty for OVCF.
Methods: A retrospective analysis was performed on 60 patients treated with PVP from January 2020 to December 2021. Patients were divided into two groups according to the treatment method, 30 patients in the PVP group received PVP and 30 patients in the PCVP group received PCVP. The VAS score, ODI score, bone cement dosage, and leakage were compared between the two groups preoperatively, immediately postoperatively, and 7 and 30 days postoperatively.
Results: VAS scores in the PCVP and PVP groups before, immediately after, and 7 days after surgery were P > 0.05, and the difference was not statistically significant; ODI score in group 1 before surgery was not statistically significant (P > 0.05); bone cement injection volume in the PVP group was significantly higher than that in the PCVP group (P < 0.05), and the difference was statistically significant; the difference in bone cement leakage between the two groups was not statistically significant (P > 0.05).
Conclusion: Under the same puncture conditions, the PCVP group used the method of injection while retreating to achieve a better bone cement dispersion effect by using less bone cement and achieving uniform dispersion of bone cement. It can relieve the patients' back pain and improve the back function.

1. Research Methodology

1.1. General Information

A retrospective analysis was conducted on 30 OVCF patients (30 vertebral bodies) treated with PVP from January 2020 to December 2021 (PVP group) and 30 OVCF patients (30 vertebral bodies) treated with PCVP (PCVP group). All patients underwent preoperative bone mineral density examination to indicate severe osteoporosis. MR examination or ECT examination was performed to determine the fracture site and identify whether it was a fresh fracture.

1.2. Surgical Methods

All patients were prone on the hospital bed, and the operation area was anesthetized (5 ml, 0.1% lidocaine), routinely disinfected, and covered.

In the PVP group, unilateral needling is performed under c-arm guidance, usually with severe symptoms. If there was no significant difference in symptoms on both sides, the left side was selected for puncture. Fluoroscopy confirmed that the needle insertion position was good. The working sleeve was removed, and the wound was covered with a sterile dressing at the end of the drawing period and 2-3 minutes after injection. About 10 to 15 minutes after the injection, after confirming that the residual bone cement in vitro is completely solidified, the patient is turned to the supine position on the flat car with the cooperation of the nurse, then returned to the ward, and the operation is completed.

In the PCVP group, the PCVP operation was the same as that of the PVP. Usually, the side with severe symptoms was selected for puncture. A working cannulation with a diameter of 3.7 mm was selected for puncture and the needle position was confirmed by using fluoroscopy. In the responsible vertebral body, take out the angle syringe when necessary and inject bone cement. Pull out the angle syringe 1∼2 minutes after injection and then rotate and pull out the working sleeve. Cover the wound. About 10 to 15 minutes after the injection, after confirming that the residual bone cement in vitro is completely solidified, the patient is turned to the supine position on the flat car with the cooperation of the nurse, then returned to the ward, and the operation is completed.

1.3. Postoperative Treatment

After returning to the ward, the patient was instructed to stay in bed for 2 hours, asked to take a supine position, pain relief and symptomatic treatment according to the patient's pain condition was provided, and was routinely given antiosteoporosis treatment. 2 hours after surgery, patients were instructed to walk moderately while wearing the waist circumference. According to the patient's postoperative recovery, we planned to discharge the patient after DR examination and explained the preventive measures, postoperative follow-up, and regular antiosteoporosis matters. All patients successfully underwent the operation.

1.4. Observation Indicators

VAS score, ODI score, and bone cement injection volume were observed before surgery, immediately after surgery, and 7 days and 30 days after surgery.

Bone cement leakage rate: high-resolution CT plain scan was performed after operation, and cement leakage manifests beyond the vertebral body margins. Bone cement distribution and diffusion: select the layer with the largest bone cement distribution area in the CT image for plane division. On the cross section, the vertebral body was divided into two areas, left and right, in the middle, and each area was divided into 3 subareas, the front, middle, and rear, and each area was divided into 4 equal parts, for a total of 24 subareas. If bone cement covers the eight regions, then the distribution of bone cement can theoretically be considered ideal [1].

Pain evaluation [2]: pain was assessed on the Visual Analog Scale (VAS) from 0 to 10 at each time point. The higher the OVCF score, the higher the pain.

OSS Disability Index (ODI) [3]: the degree of disability increases with the OVCF score, which ranges from 0 to 100 according to the ODI score.

1.5. Statistical Processing

SPSS 22.0 software is used for data statistical analysis. The data of normal distribution were expressed as (), and the independent sample T test was used for intergroup comparison. The count data is represented by %, and the test method is χ2. P < 0.05 indicates statistically significant difference between groups.

2. Results

2.1. General Data

There was no statistical significance in the general data (P > 0.05, Table 1).

Table 1

General data of patients ()/[cases (%)].

Group	Age range	Duration of disease (days)	Sex
			M	F
PCVP group (n = 30)	68.4±2.3	4.8±0.5	8	22
PVP group (n = 30)	69.2±2.4	5.0±0.6	10	20
t/c 2	1.318	1.403	0.318
P	0.193	0.166	0.573

2.2. VAS Scores of Pain in Both Groups

As shown in Table 2, the VAS scores of pain in the PCVP and PVP groups preoperatively, postoperatively, and 1 week postoperatively were P > 0.05.

Table 2

Pain VAS scores of patients presurgery, postsurgery, and 1 week and 1 month (, points).

Group	Presurgery	Postsurgery	1 week after surgery
PCVP group	8.10 ± 0.67	3.03 ± 0.69	1.54 ± 0.12
PVP group	7.97 ± 0.78	3.07 ± 0.80	1.63 ± 0.22
P	0.832	0.837	0.054

Note.P < 0.05 difference is statistically significant.

2.3. ODI Functional Index and Bone Cement Injection Volume before and after Surgery in Both Groups

The results of the data in Table 3 show that the ODI score before and after surgery in both groups (P > 0.05) and the amount of bone cement injection in the PVP group were significantly higher than that in the PCVP group (P < 0.05).

Table 3

Preoperative and postoperative ODI score and bone cement injection volume ().

Group	ODI functional index		Bone cement injection volume (ml)
	Presurgery	Postsurgery
PCVP group	38.13 ± 3.22	21.45 ± 2.21	3.92 ± 1.41
PVP group	37.94 ± 3.18	22.23 ± 2.30	4.86 ± 1.21
P	0.819	0.186	0.007

2.4. Bone Cement Leakage and Dispersion in the Two Groups

As shown in Table 4, there was no significant difference in bone cement leakage between the two groups, P > 0.05.

Table 4

Bone cement leakage and bone cement dispersion [cases (%)].

Group	Bone cement leakage	Degree of bone cement dispersion
PCVP group	2/6.67%	27/90.00%
PVP group	5/40.00%	18/60.00%
X 2/P	1.456/0.228	7.2/0.007

Note.P < 0.05 difference is statistically significant.

3. A Typical Surgical Case

As shown in Figure 1, in the patient's unilateral vertebroplasty, the curved puncture cannula was successfully punctured with satisfactory puncture results (Figures 1(a) and 1(b)). The angle of inclusion in the coronal plane was 27° (Figures 1(c) and 1(d)), and the injection of bone cement was successfully completed while retraction was taking place (Figures 1(e) and 1(f)). The postoperative CT images showed that the bone cement injection was symmetrically dispersed and evenly diffused (Figures 1(g) and 1(h)), and the surgical result was good.

Figure 1

Intraoperative and postoperative CT images of unilateral arcuate vertebroplasty. (a, b) show the front and side views after successful puncture of the arcuate puncture cannula; (c, d) show the front and side views of the arcuate guide needle placed in the vertebral body; (e, f) show the front and side views after bone cement injection; (g, h) show the CT images after bone cement injection.

4. Discussion

Some researchers believe [4] that the bilateral arch root approach is more advantageous for relieving patients' postoperative low back pain because the relief of patients' postoperative pain depends largely on the symmetrical distribution of bone cement in the injured vertebrae, which equalizes the stress in the injured vertebrae, which is one of the important mechanisms for pain relief. However, some studies [5] have shown that the use of unilateral pedicle approach with cement injection has been effective in restoring the height of the injured vertebral body, and the use of bilateral approach will undoubtedly increase the risk of surgery, prolong the operation time, and increase the X-ray exposure time of the patient, which may not be beneficial to the patient. The results of this study also confirm that the operative time and the number of X-ray exposures (time) were significantly higher in the bilateral group than in the unilateral group. Reference [6] suggests that there is no significant difference in recent clinical outcomes between bilateral and unilateral pedicle approaches for the treatment of osteoporotic vertebral compression fractures, and the question has mostly focused on which approach is more effective in terms of clinical outcomes (especially pain relief) for patients. Angled vertebroplasty is based on a unilateral puncture in which a nickel-titanium alloy guide pin with ultra-high elasticity and good metallic mechanical strength is delivered through a puncture cannula to the other side of the vertebral body, creating a lateral space to facilitate delivery of the cannula [7]. The anterior edge of the vertebral body midline is the outlet of the anterior cement, and the bone cement can diffuse laterally without resistance. The arc-shaped diffusion distribution ensures symmetrical distribution of the bone cement, allowing it to be evenly distributed on both sides of the vertebral body, with the same advantages as bilateral puncture. It is important to pay attention to the depth and direction of the puncture cannula to avoid puncturing the anterior edge of the vertebral body or the anterior part of the upper and lower end plates; thus, increasing the risk of bone cement leakage [8]. This study focuses on the application of PCVP in the treatment of OVCF.

Based on the PVP-modified PCVP, the bone cement can spread through the anterior part of the spine to the middle of the spine without increasing the puncture angle, and the injection site is highly mobile and symmetrically and uniformly distributed, which balances the strength of both sides of the vertebral body and solves the problem of uneven distribution of bone cement in traditional treatment, resulting in poor pain [9]. The comparison of pain scores between the two groups after surgery showed that there was no significant difference in visual scores between the PCVP and PVP groups preoperatively, postoperatively, and 7 days after surgery, indicating that PCVP and PVP can be very effective. Our results showed no statistically significant differences in ODI score, VAS scores, and PVP at 1 day, 2 months, and 6 months after PCVP. In addition, References [10, 11] and others have confirmed that PCVP has no significant advantage in relieving pain and improving spinal cord function.

Traditional OVCF vertebroplasty mainly consists of PVP and PKP. PVP usually requires increased cement injection to achieve diffusion, but also increases the risk of cement leakage as a result. If the PKP procedure is performed with balloon expansion, it can better restore the height of the injured vertebral body and compact the cancellous bone around the left cavity, forming an artificial barrier to prevent cement leakage. If PKP is performed by balloon expansion, the height of the injured vertebral body can be better restored, and the cancellous bone around the left cavity can be compacted to form an artificial barrier to prevent cement leakage and reduce the injection of bone cement. However, from a biomechanical point of view, References [12, 13] found that cement-induced increase in vertebral stiffness increases the risk of fracture of adjacent vertebrae. In addition, vertebral bone cement increases the likelihood of secondary Kummell's disease [14, 15].

In angled vertebroplasty, an angled needle creates a small gap between the vertebral fractures and is injected posteriorly, and better spreading of the vertebrae and the same therapeutic results can be achieved with a small amount of bone cement [16]. Some studies even suggest that a large amount of bone cement filling should be limited to less than 5 ml, which can greatly reduce the leakage rate of bone cement [17]. In the early stage of injection, the bone cement had relatively good mobility and high dispersion in the vertebral body but with a high infiltration rate; in the late stage of injection, the bone cement had poor relative mobility, low dispersion in the vertebral body, uneven distribution, and low leakage rate [18]. In this study, we found that the amount of bone cement injected in the PVP group was significantly higher than that in the PCVP group, and the difference was statistically significant. References [19, 20] also confirmed that there was also no significant difference in bone cement leakage between the two groups, which is consistent with the present study. This is related to the fact that the surgeons in the surgical group may have a long history of PVP and have extensive clinical experience in reducing bone cement leakage.

5. Conclusion

In patients with OVCF, the injection was performed by the method of injection while retreating under the same puncture conditions, and the use of less bone cement can achieve uniform dispersion of bone cement, which can achieve better dispersion of bone cement, relieve patients' back pain, and improve back function. However, this study has disadvantages such as small sample size, no long-term follow-up, and only patients with newly occurred vertebral compression fractures were included, and the evaluation of postoperative vertebral stability and whether fractures occurred need further improvement, and the results may be biased, and more in-depth studies will be conducted in the next step.