Can an unipedicular approach replace bipedicular percutaneous vertebroplasty for osteoporotic vertebral compression fracture?

Abstract

OBJECTIVE:

To compare outcomes of unipedicular versus bipedicular approach for percutaneous vertebroplasty for the treatment of thoracolumbar acute osteoporotic vertebral compression fracture (AOVCF).

METHOD:

From November 2014 to September 2015, 382 patients with AOVCF were randomly assigned to the unipedicular and bipedicular groups. Clinical outcomes and complications were compared.

RESULTS:

Both groups were comparable with respect to bone cement leakage and adjacent vertebral fractures ( $P>$ 0.05). Although the bipedicular approach was found to be superior in terms of reduction of kyphosis and loss of reduction, frequency of x-ray fluoroscopy, VAS and ODI scores, the volume of cement injected and operating time, the between-group differences were not statistically significant ( $P>$ 0.05). Nerve root stimulation was more frequent in the unipedicular group ( $P<$ 0.05).

CONCLUSIONS:

The clinical and radiological outcomes of both procedures were comparable. The unipedicular approach was associated with more nerve root stimulation.

Keywords

Percutaneous vertebroplasty thoracolumbar acute osteoporotic vertebral fracture unipedicular bipedicular

1. Introduction

The prevalence of acute osteoporotic vertebral compression fracture (AOVCF) is increasing with the aging of the population. AOVCF is a frequent cause of persistent back pain, which significantly impairs mobility and quality of life. Since the first report of percutaneous kyphoplasty in 1987 for the treatment of painful hemangioma involving the cervical spine in a young female patient [1], the indications for percutaneous vertebroplasty (PVP) or percutaneous kyphoplasty (PKP) have extended to AOVCF [2, 3]. Many studies have demonstrated that PVP has a high efficacy in immediate pain relief, and the key for successful PVP is to distribute the cement homogeneously within the vertebral body without causing leakage from the bone [3]. Some studies have shown superior long-term outcomes and fewer instances of cement leakage with the bipedicular approach in comparison to the unipedicular approach [4, 5, 6, 7]. However, others appear to favor the unipedicular approach due to shorter surgical time, lower x-ray irradiation and fewer complications [8]. We undertook this single-center, double-blind, randomized controlled trial to compare the clinical outcomes and complications between these two approaches.

2. Materials and methods

The study protocol was approved by the Ethics Committee at the Honghui Hospital, Xi’an Jiaotong University Health Science Center in China and this clinical trial was registered at the Chinese Clinical Trial Registry (no. ChiCTR-TRC-14004378). Written informed consent was obtained from each participant before the start of the trial.

Random allocation was done using a computer-generated randomization process. The process was double blinded, with neither the patients nor the examiners knowing the test group allocation. Allocation concealment was ensured using serially numbered, sealed envelopes.

Figure 1.

CONSORT diagram detailing the study flow from enrollment through analysis. Three hundred and eighty-two patients were randomized to one of two groups: unipedicular group ( $N=$ 198) and bipedicular group ( $N=$ 184). Forty-four patients in unipedicular group and 43 patients in bipedicular group were lost to follow-up and adjacent vertebral fractures; 291 patients were included in the final analysis (151 in the unipedicular group and 140 in the bipedicular group).

The selection of the study population is shown in Fig. 1. Inclusion criteria were: (1) age between 65 and 75 years; (2) anterior vertebral body compression (15–70% of the vertebral height); (3) pain $\geqslant$ 7, as measured on a visual analogue scale, inability to tolerate long-term bed rest and poor tolerance to analgesic medication for at least 2 weeks; (4) magnetic resonance (MR) imaging showing a single-level vertebral hypointense signal on T1-weighted images, with hyper intense signal on T2-weighted and MR T2-weighted short-tau inversion recovery (STIR) sequences; (5) decreased bone mineral density (BMD, T score $\rightarrow$ 2.5); (6) fracture level: T11 to L2; and (7) on the basis of CT imaging, the fracture classified as A1 according to the AO classification [9].

The exclusion criteria were: (1) intolerance to open surgery; (2) severe comorbidity (heart, liver, kidney, or lung); (3) systemic or local spine infection; (4) secondary osteoporosis (due to corticosteroid therapy, endocrine disorders or an inflammatory process); (5) uncorrected coagulopathy; (6) spinal metastatic cancer; (7) burst fracture with or without neurological symptoms; and (8) refusal to participate in the study.

2.1 Procedures

All procedures were performed by the same surgeon. The procedure was performed under partial infiltration anesthesia using 1% lidocaine injection.

In the unipedicular group, the trocars were inserted through the lateral margin of the pedicle of the side that was more compressed, at the 3 o’clock position on the right side or at the 9 o’clock position on the left side (about 35–40 ${}^{\circ}$ ). When the needle tip reached the medial wall of the pedicle, a lateral fluoroscopic view was used to verify that the needle did not invade the vertebral canal. When lateral fluoroscopy showed that the tip of the needle was located at the anterior one-third of the vertebral body, it indicated that the needle tip had reached the midline of the vertebral body, and was in the optimal position. If the needle was not in this optimal position, or caused nerve root stimulation, its position was corrected. Then a large bore needle was placed transpedicular into the vertebral body and polymethyl methacrylate (PMMA) was injected. After every 0.5 mL of PMMA injection, fluoroscopy was used to monitor its dispersion (Fig. 2A–D). A contralateral small skin puncture was made under partial infiltration anesthesia approximately 2.5 cm from mid-line; however, PMMA was not injected.

Figure 2.

CT scan showing the position of inserted trocars, extraversion angle and distribution of bone cement in unipedicular group (A–D) and bipedicular group (E–H).

In the bipedicular group, two trocars were simultaneously inserted into both pedicles of the fractured vertebra; the needle entry points were at the 3 o’clock position on the right side and at the 9 o’clock position on the left side, requiring less medial inclination (about 10–15 ${}^{\circ}$ ) in comparison to the unipedicular group to achieve the above appearance. When lateral fluoroscopy indicated that the tip of the needle was located at the anterior one-third of the vertebral body, the needle tip reached the one-fourth of the vertebral body on anteroposterior radiographs. Then two large bore needles were placed transpedicularly into the vertebral body. During the injection PMMA process, after every 1.0 mL of PMMA injection (0.5 mL on each side, simultaneously), the dispersion of PMMA was monitored by fluoroscopy (Fig. 2E–H).

The injection procedure was carefully controlled under anteroposterior and lateral fluoroscopy. Whenever there was bone cement leakage or the cement reached the dorsal quarter of the vertebral body, the injection was terminated. All patients were prescribed a thoracolumbar hyperextension brace for 1 month and underwent treatment of osteoporosis with 5 mg/day risedronate sodium (for 6 months) to prevent refracture or adjacent vertebral fractures.

2.2 Clinical outcomes

Both groups were compared with respect to operation time, volume of PMMA injected, frequency of X-ray fluoroscopy, and perioperative complications, such as nerve root stimulation, bone cement leakage, and adjacent vertebral fractures. CT-3D was carried out in all cases to assess the distribution of bone cement and to look for cement leaks at 1 week post operation. The standing position plain radiographs were obtained at week 1, 1 month and 3 month post-surgery to assess the kyphotic angle. Surgical correction in the angle of kyphosis was assessed by calculating the mean difference between the pre- and postoperative measurements. The postoperative loss of correction was assessed by calculating the mean difference between the measurements made immediately postoperatively and those at the final follow-up examination.

Back pain was assessed with the Visual Analog Scale (VAS) score (11 levels ranging from 0 (no pain) to 10 (the strongest pain having ever been experienced)) and Oswestry low back pain disability index (ODI). The incidence of recurrent and adjacent vertebral fractures was also evaluated. Patients who developed new back pain during the follow-up period were brought back for MR imaging of the thoracic and lumbar spine. The new fractures were determined on MR imaging.

2.3 Statistical analyses

All statistical analyses were performed using SPSS software, version 12 (SPSS Inc., Chicago, IL, USA). Between-group differences were assessed using the Student’s $t$ test and the Mann-Whitney U test for continuous and discrete variables, respectively. $P<$ 0.05 was considered indicative of a statistically significant between-group difference.

3. Results

Between November 2014 and September 2015, 682 patients with AOVCF of the thoracolumbar spine were treated at our trauma centre. Of these, 430 met the inclusion criteria. 48 patients refused to participate in the study. All participants were followed up for six months. In the unipedicular group, 28 patients were lost to follow-up and 19 patients had adjacent vertebral fractures. In the bipedicular group, 29 patients were lost to follow-up and 16 patients had adjacent vertebral fractures. Forty-seven (23.7%) of the 198 patients in the unipedicular group and forty-five (24.4%) of the 184 patients in the bipedicular group were not included in the analysis. At the time of follow-up, the preoperative data showed no significant intergroup differences with respect to age, gender and BMD T score ( $P=$ 0.13) (Table 1).

Table 1
Baseline characteristics of patients by study group

	Unilateral group	Bilateral group	$P$
No. of cases	151	140	–
Age, mean $\pm$ SD, yr	68.5 $\pm$ 5.23	69.4 $\pm$ 4.35	0.12
Sex (female/male)	115/36	119/31	0.18
BMD T score	$-$ 3.1 $\pm$ 0.4	$-$ 3.2 $\pm$ 0.35	0.13
No. of cases
T11	35	31	0.36
T12	42	40	0.23
L1	46	42	0.33
L2	28	27	0.34

SD, standard deviation; BMD, bone mineral density.

Table 2

Clinical and radiological findings by study group

	Unipedicular	Bipedicular	$P$
Operation time (min)	35.3 $\pm$ 8.9	31.2 $\pm$ 6.0	0.33
Volume of cement (mL)	4.5 $\pm$ 0.3	5.0 $\pm$ 0.5	0.22
Frequency of X-ray fluoroscopy	18.5 $\pm$ 3.8	17.2 $\pm$ 2.4	0.31
Nerve root stimulation	16	3	0.01
Preoperation kyhpotic angle	21.03 $\pm$ 3.42	21.56 $\pm$ 2.78	0.28
At 1-week kyhpotic angle	11.55 $\pm$ 2.21	10.01 $\pm$ 2.42	0.42
3-mouth f/u kyhpotic angle	15.12 $\pm$ 2.19	14.33 $\pm$ 2.59	0.36
6-mouth f/u kyhpotic angle	19.72 $\pm$ 2.34	17.43 $\pm$ 2.09	0.10
Surgical correction angle	11.23 $\pm$ 3.05	12.05 $\pm$ 2.83	0.32
Loss of correction	5.35 $\pm$ 2.05	4.87 $\pm$ 1.87	0.26
Bone cement leakage (n)	36 (23.84%)	33 (23.6%)	0.28
Venous system	5	4	0.22
Vertebral canal	1	1	0.31
Intravertebral space	14	15	0.29
Paravertebral soft tissue	15	12	0.11
Pulmonary embolism	1	1	0.31
Adjacent vertebral fractures	19 (12.6%)	16 (11.4%)	0.38

Data are presented as mean $\pm$ standard deviation unless specified otherwise.

3.1 Operative data

In the unipedicular and bipedicular groups, the mean operation time, frequency of x-ray fluoroscopy and mean volume of cement injected were 35.3 $\pm$ 8.9 vs. 31.2 $\pm$ 6.0 min ( $P=$ 0.33), 4.5 $\pm$ 0.3 vs. 5.0 $\pm$ 0.4 mL ( $P=$ 0.22), and 18.5 $\pm$ 3.8 vs. 17.2 $\pm$ 2.4 ( $P=$ 0.31), respectively. The perioperative data are summarized in Table 2.

3.2 Radiographic findings

The correction angle was higher, and the loss of correction was lower in the bipedicular group as compared to that in the unipedicular group; the differences, however, did not reach statistical significance ( $P=$ 0.28) (Table 2). All bone cement exceeded the midline of vertebral body and in 113 cases bone cement exceeded three quarters of the vertebral body in the unipedicular group, all bone cement distribution were uniform in the bipedicular group.

3.3 Clinical outcomes

Adjacent vertebral fractures developed in 35 patients (N $=$ 382, 9.2%) during 6 months of follow-up. However, no recurrent fractures occurred in any of the patients. Of the 35 patients that developed adjacent vertebral fractures, 19 (12.6%) were in the unipedicular group and 16 (11.4%) were in the bipedicular group ( $P=$ 0.38). Preoperative VAS scores and ODI and that at the final follow-up visit are shown in Table 3. The VAS and ODI scores were better in the bipedicular group as compared to that in the unipedicular group at one week post-surgery, 1, 3, and 6 months post-surgery; the differences, however, did not reach statistical significance ( $P>$ 0.05).

Table 3
VAS score and ODI of patients by study group

	VAS		$P$	ODI		$P$
	Unipedicular	Bipedicular		Unipedicular	Bipedicular
	( $N=$ 151)	( $N=$ 140)		( $N=$ 151)	( $N=$ 140)
Preoperation	7.9 $\pm$ 0.5	8.0 $\pm$ 0.4	0.36	61.3 $\pm$ 5.6	62.6 $\pm$ 5.9	0.42
1-week follow-up	3.1 $\pm$ 0.5	2.9 $\pm$ 0.3	0.22	28.5 $\pm$ 2.1	26.9 $\pm$ 1.9	0.33
1-month follow-up	2.2 $\pm$ 0.3	2.0 $\pm$ 0.1	0.34	21.6 $\pm$ 2.2	20.1 $\pm$ 1.5	0.44
3-month follow-up	2.0 $\pm$ 0.2	1.8 $\pm$ 0.1	0.23	18.1 $\pm$ 1.8	16.0 $\pm$ 1.1	0.33
6-month follow-up	2.0 $\pm$ 0.2	1.9 $\pm$ 0.1	0.41	20.1 $\pm$ 1.3	18.0 $\pm$ 1.1	0.31
Recovery rate	80.8%	81.3%	0.32	78.3%	80.1%	0.42

Data are presented as mean $\pm$ standard deviation. ODI, Oswestry disability index; VAS, visual analogue scale.

3.4 Perioperative complications

Leakage of bone cement outside the vertebral body was noted on postoperative anteroposterior and lateral radiographs and on CT scan in 36 (23.84%) patients in the unipedicular group and in 33 (23.6%) patients in the bipedicular group ( $P=$ 0.28). Despite the high incidence of leakage, no clinical symptoms were observed. The incidence of nerve root stimulation was greater (16 vs. 3) in the unipedicular group. No major complications, such as osteomyelitis or radicular neuritis were observed (see Table 2).

4. Discussion

AOVCF is associated with pain, deformity, disability and poor quality of life. PVP provides rapid and long lasting pain relief and has gained popularity as an effective treatment modality for AOVCF [6].

In some studies, the bipedicular approach was shown to achieve symmetrical distribution of bone cement in the vertebral body [4]. Others have shown that the bipedicular approach is not required because bone cement is liable to be distributed uniformity in the vertebral body when unipedicular puncture point reaches the median vertebral body [10]. Therefore, which surgical approach should be selected remains controversial. In this study, we sought to compare the two techniques with respect to clinical outcomes and complications in patients with single-level thoracolumbar AOVCF.

The traditional view, as also confirmed in our previous study [11], is that unilateral PKP entails a shorter surgical time and lower x-ray irradiation compared with the bilateral approach [4]. In the present study, the bilateral trocars were simultaneously inserted and PMMA were simultaneously injected in patients of the bipedicular group. The mean duration of operation was longer (31.2 $\pm$ 6.0 vs. 35.3 $\pm$ 8.9 min) and the frequency of x-ray fluoroscopy was higher (17.2 $\pm$ 2.4 vs. 18.5 $\pm$ 3.8) in the unipedicular group; however, the difference was not statistically significant. There may be a need to correct the needle angle two, three or even more times in the unipedicular group. Conversely, there is a need for bilateral simultaneous puncture and injection of PMMA in the bipedicular group.

Radiological evidence also indicated the advantage of the bilateral approach in terms of reduction in kyphosis with the loss of reduction being lesser as compared to that in the unilateral group [12, 13]. We found that the correction angle was higher (11.23 $\pm$ 3.05 vs. 12.05 $\pm$ 2.83, $P=$ 0.32) and the loss of correction lower (5.35 $\pm$ 2.05 vs. 4.87 $\pm$ 1.87, $P=$ 0.26) in the bipedicular group as compared to that in the unipedicular group. The differences were not statistical significant ( $P>$ 0.05) (Table 2).

Long et al. reported that the distribution of bone cement is critical to the stabilization of fractures of vertebral body and pain relief, and that the stress distribution achieved by unipedicular approach was inferior to that achieved with the bipedicular approach [14]. In our study, the vertebral needle reached anterior third of the vertebral body on the lateral view, but not all cases reached the midline of the vertebral body on the posteroanterior view in the unipedicular group [15]. The bone cement exceeded the midline of vertebral body in all cases, but and exceeded three quarters of the vertebral body in only 113 cases in the unilateral group. To achieve a more uniform distribution of bone cement, intertransverse vertebroplasty may be necessary [11].

Tohmeh et al. found no significant difference between the therapeutic efficacy of unipedicular and bipedicular approaches [10], but Song et al. reported greater improvement in VAS scores in the unipedicular group as compared to that in the bipedicular group ( $P<$ 0.001) [16]. Zhang et al. [5] reported superior three-month follow-up outcomes with bipedicular approach for PKP as compared to that with unipedicular approach. In the present study, The VAS and ODI scores were better in the bipedicular group as compared to that in the unipedicular group at one week post-surgery, 1, 3, and 6 months post-surgery; the differences, however, did not reach statistical significance ( $P>$ 0.05). This may be related to a more uniform PMMA distribution; however, the bipedicular pedicle is perforated by the needle, and its repositioning may unseal the cortical defect and cause more blood loss into the tissue space and effect pain relief in the bipedicular group [17]. Since this was a double-blind trial, a small skin puncture was made on the contralateral side in patients of the unipedicular group, to maintain the concealment of group allocation from the examiners. Additionally, this could have reduced the effect of soft tissue injury on patient reported outcomes such as ODI and VAS scores.

Previous studies have shown that both bipedicular and unipedicular PVP are relatively safe; however, unipedicular approach results in fewer complications [4]. In the present study, the leakage of the bone cement outside the vertebral body was noted on post-operative anteroposterior and lateral radiographs and CT scan in 36 (23.84%) patients in the unipedicular group and 33 (23.6%) in the bipedicular group ( $P=$ 0.28). Besides, there was no significant difference with respect to the sites of leakage between the two groups. No statistically significant between-group difference was observed with respect to cement leakage into intervertebral disk space and to occurrence of adjacent vertebral fractures. (14 vs. 15 and 19 [12.6%] vs. 16 [11.4%] $P>$ 0.05) [18]. The two patients with pulmonary embolism (1 vs. 1; $P=$ 0.31) in our study did not develop any symptoms such as hypotension, acute respiratory distress or refractory hypoxemia, and were treated with unfractionated heparin for 6 months [19]. However, the incidence of nerve root stimulation was greater (16 vs. 3, $P<$ 0.05) in the unipedicular group. This may have been attributable to the needle tip reaching the midline of the vertebral body, greater abduction angle of the needle (about 35–40 ${}^{\circ}$ ) and repeated correction of the position to achieve optimal position.

There are certain limitations of the study which ought to be mentioned. The intervals of follow-up in the study were kept at 1 week, 1 month, 3 month and 6 month post-surgery, which was due to the relatively older age of the patients and consequent inability to comply with more frequent follow-up. Additionally, a multi-centre study with a larger sample size and longer duration of follow-up is needed to confirm our findings.

In conclusion, our study reveals that both unilateral and bilateral puncture during PVP is effective in the treatment of AOVCF. The clinical and radiological outcomes of both treatment procedures were comparable. However, unipedicular approach was associated with greater nerve root stimulation. Unipedicular approach may be used instead of bipedicular percutaneous vertebroplasty for osteoporotic vertebral compression fracture.

Footnotes

Acknowledgments

The Social Development of Science and Technology Research grants of the Department of Science and Technology at Shaanxi Province (grant nos. 2016SF-072 and 2017SF-233) were received in support of this work.

Conflict of interest

None to report.

References

Galibert

Deramond

Rosat

Le Gars

. [Preliminary note on the treatment of vertebral angioma by percutaneous acrylic vertebroplasty]. Neurochirurgie. 1987; 2(33): 166-168.

Deramond

Depriester

Galibert

Le Gars

. Percutaneous vertebroplasty with polymethylmethacrylate. Technique, indications, and results. Radiol Clin North Am. 1998; 3(36): 533-546.

Kobayashi

Takizawa

Koyama

Yoshimatsu

Sakaino

Nakajima

. Unilateral transpedicular percutaneous vertebroplasty using puncture simulation. Radiat Med. 2006; 3(24): 187-194.

Zhang

Liu

Wang

Feng

Yang

Tao

Zhang

. Unipedicular versus bipedicular percutaneous vertebroplasty for osteoporotic vertebral compression fractures: a prospective randomized study. BMC Musculoskelet Disord. 2015; 16: 145. doi: 10.1186/s12891-015-0590-6

Zhang

Cai

Tao

. Unilateral or bilateral percutaneous vertebroplasty for acute osteoporotic vertebral fracture: a prospective study. J Spinal Disord Tech. 2015; 2(28): E85-88. doi: 10.1097/BSD.0000000000000147

Georgy

. Clinical experience with high-viscosity cements for percutaneous vertebral body augmentation: occurrence, degree, and location of cement leakage compared with kyphoplasty. AJNR Am J Neuroradiol. 2010; 3(31): 504-508. doi: 10.3174/ajnr.A1861

Nieuwenhuijse

Muijs

van Erkel

Dijkstra

. A clinical comparative study on low versus medium viscosity polymethylmetacrylate bone cement in percutaneous vertebroplasty: viscosity associated with cement leakage. Spine (Phila Pa 1976). 2010; 20(35): E1037-1044. doi: 10.1097/BRS.0b013e3181ddd262

Kim

Jensen

Dion

Schweickert

Kaufmann

Kallmes

. Unilateral transpedicular percutaneous vertebroplasty: initial experience. Radiology. 2002; 3(222): 737-741. doi: 10.1148/radiol.2223010718

Aebi

. Classification of thoracolumbar fractures and dislocations. Eur Spine J. 2010; 19(Suppl 1): S2-7. doi: 10.1007/s00586-009-1114-6

10.

Tohmeh

Mathis

Fenton

Levine

Belkoff

. Biomechanical efficacy of unipedicular versus bipedicular vertebroplasty for the management of osteoporotic compression fractures. Spine (Phila Pa 1976). 1999; 17(24): 1772-1776.

11.

Yan

Jiang

Liu

Hao

. A comparison between unilateral transverse process-pedicle and bilateral puncture techniques in percutaneous kyphoplasty. Spine (Phila Pa 1976). 2014; 26 Spec No.(39): B19-26. doi: 10.1097/BRS.0000000000000493

12.

Chung

Yoon

Kwon

. Comparative study of balloon kyphoplasty with unilateral versus bilateral approach in osteoporotic vertebral compression fractures. Int Orthop. 2008; 6(32): 817-820. doi: 10.1007/s00264-007-0439-1

13.

Chen

Wei

Zhang

Tang

Dong

Chen

. Comparative study of kyphoplasty for chronic painful osteoporotic vertebral compression fractures via unipedicular versus bipedicular approach. J Spinal Disord Tech. 2011; 7(24): E62-65. doi: 10.1097/BSD.0b013e318228f470

14.

Long

. Biomechanical changes following vertebroplasty by unilateral or bilateral approach: Finite element analysis. Zhongguo Zuzhi Gongcheng Yanjiu yu Linchuang Kangfu. 2009; 22(13): 4277-4280.

15.

Zhang

Gao

Chen

Ding

Gao

. Significantly reduced radiation dose to operators during percutaneous vertebroplasty using a new cement delivery device. BMC Musculoskelet Disord. 2014; 15: 260. doi: 10.1186/1471-2474-15-260

16.

Song

Eun

. Clinical and radiological comparison of unipedicular versus bipedicular balloon kyphoplasty for the treatment of vertebral compression fractures. Osteoporos Int. 2009; 10(20): 1717-1723. doi: 10.1007/s00198-009-0872-7

17.

Steinmann

Tingey

Cruz

Dai

. Biomechanical comparison of unipedicular versus bipedicular kyphoplasty. Spine (Phila Pa 1976). 2005; 2(30): 201-205.

18.

Kerkeni

Kolta

Fechtenbaum

Roux

. Spinal deformity index (SDI) is a good predictor of incident vertebral fractures. Osteoporos Int. 2009; 9(20): 1547-1552. doi: 10.1007/s00198-008-0832-7

19.

Lee

Kim

J-K

. Multiple pulmonary cement embolism after percutaneous vertebroplasty. QJM. 2013hct079.

Can an unipedicular approach replace bipedicular percutaneous vertebroplasty for osteoporotic vertebral compression fracture?

Abstract

OBJECTIVE:

METHOD:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

2. Materials and methods

2.3 Statistical analyses

3. Results

Table 1 Baseline characteristics of patients by study group

3.2 Radiographic findings

3.3 Clinical outcomes

Table 3 VAS score and ODI of patients by study group

4. Discussion

Footnotes

Acknowledgments

Conflict of interest

References

Table 1
Baseline characteristics of patients by study group

Table 3
VAS score and ODI of patients by study group