Keywords unilateral transverse process-pedicle approach - vertebral augmentation - osteoporotic
vertebral compression fractures - Systematic review - meta-analysis
Schlüsselwörter einseitiger Querfortsatz-Pedikel-Ansatz - Wirbel Augmentation - osteoporotische Wirbelkörperkompressionsfrakturen
- Systematische Überprüfung - Meta-Analyse
Introduction
Osteoporotic vertebral compression fracture (OVCF) is a common disease in the department
of orthopedics. Due to long-term chronic pain and spinal deformity, the patient’s
daily activities are
significantly limited [1 ]. Percutaneous vertebral augmentation (PVA), including percutaneous vertebroplasty
and percutaneous kyphoplasty, is the main treatment for OVCF, and both percutaneous
vertebroplasty and percutaneous kyphoplasty have shown promising results [2 ]
[3 ]. By injecting bone cement into the vertebra, the operation can enhance the strength
and stability of the patient’s vertebra and avoid collapse, thus relieving the
patient’s pain and other clinical symptoms with definite effects. In order to reduce
surgical trauma, reduce radiation exposure, and increase surgical safety, many scholars
have carried out
in-depth studies on puncture techniques and paths. Because a successful puncture can
not only avoid complications, it also promotes the symmetrical distribution of bone
cement after puncture
[4 ]. Although many puncture methods have been designed, including pedicle, paravertebral,
anterolateral, and posterolateral approaches, PVA with CTPA under the C-arm is the
most commonly used approach [5 ]
[6 ]. A unilateral pedicle approach can meet the surgical requirements at one time, but
if the inclination is small, the cement usually deposits on one side of the vertebral
body, and there is no force on the opposite side. If the angle of inclination is too
large, the inner wall of the pedicle can be easily damaged, which can lead to serious
complications such as
intraoperative bone cement leakage, nerve root leakage, or spinal cord injury. Bilateral
pedicle approaches can avoid these problems; however, an additional puncture increases
the risk of
nerve injury and radiation [7 ]
[8 ]. It is a challenge to address these issues with a unilateral puncture approach without
increasing the risk of surgery. Yan et al. [9 ] reported that the puncture point of the traditional pedicle approach is closer to
the facet joint, which is highly likely to damage the facet joint and cause postoperative
lumbago pain. Therefore, a unilateral trans transverse process-pedicle approach was
proposed for PVA in the treatment of senile OVCF. While avoiding damage to the articular
process, the
operative time, bone cement injection amount, and leakage rate of unilateral PVA were
significantly lower than that of the traditional pedicle approach. However, there
is no medical-based
evidence to confirm the safety and effectiveness of unilateral UTPA in the treatment
of OVCF, and there are still clinical controversies about the therapeutic effects
of different
approaches.
Methods
Search strategy
The Cochrane Library, PubMed, and Embase databases were searched to September 2021
for all the qualified studies in order to analyze the effect of UTPA versus CTPA in
the treatment of OVCF.
Literature was also identified by tracking reference lists from papers and Internet
searches. Two investigators independently extracted data, and a third investigator
was involved when a
disagreement occurred.
Study selection
To be included in the meta-analysis, studies should meet the following criteria:
Comparative studies: randomized controlled trails (RCT), prospective or retrospective
case-control study, or cohort study.
The included patients had OVCF, and severe back pain was related to OVCF.
The test group was UTPA, and the control group was treated with CTPA.
Studies qualified when at least one of the following outcomes were given: improvement
on the visual analogue scale (VAS) and the Oswestry Disability Index (ODI), kyphotic
wedge angle,
and incidence of cement leakage.
The publications were available in English or Chinese.
Study design: RCTs and prospective clinical trials were regarded as eligible in the
present study.
The following studies were excluded from the review:
Case reports, theoretical research, conference report, systematic review, meta-analysis,
expert comment, and economic analysis.
The outcomes were not relevant.
Data extraction
Two reviewers determined study eligibility independently. A third investigator was
involved to reach an agreement. The analyzed data were extracted from all the included
studies and
consisted of two parts: basic information and main outcomes. The first part was about
the basic information: the authors’ name, the publication year, study design, sample
size of each group,
surgical options, and percentage of gender, age, and follow-up time. The second part
was the clinical outcomes: VAS scores, ODI, kyphotic wedge angle, and incidence of
cement leakage. The
studies were performed by two reviewers independently. Any arising difference was
resolved by discussion.
Quality assessment
The included studies were evaluated according to the Newcastle-Ottawa Quality Assessment
Scale (NOS) recommended by the Cochrane Non-randomized Research Center. The NOS scale
scoring system
evaluates the literature in three parts (maximum score is 9), which are:
Selection of research objects (4 points)
Comparability between groups (2 points)
Determination of exposure factors and outcome indicators in case-control and cohort
studies (3 points)
A score of 0~3 points was considered low-quality research, 4~6 points as medium quality
research, and 7~9 as high-quality research. Literatures with NOS scores of 6 and above
were eligible
for meta-analysis [10 ].
Data analysis
Statistical analysis was performed using RevMan5.3 software provided by the Cochrane
collaboration. Standard mean difference (SMD) or weighted mean difference (WMD) and
relative risk (RR)
were used as effect analysis statistics for continuous variables and dichotomous variables,
respectively. The corresponding 95% confidence interval (CI) of the two types of variables
was
calculated. The χ2 test was used for heterogeneity analysis (test standard was set as α = 0.05), and
I2 was used for quantitative judgment of heterogeneity. When
p < 0.05 or I2 > 50%, significant heterogeneity between studies was considered and a random effect
model was used; otherwise, a fixed effect model was used to synthesize the
results of various studies. A funnel plot was used to analyze potential publication
bias. If the symmetry is good, the possibility of publication bias is small.
Results
Characteristics of the included studies
By searching multiple databases and sources, we identified 199 articles by the index
words. After screening titles and abstracts, 144 articles were excluded, leaving 55
articles for further
evaluation. During full-text screening, 45 articles were excluded due to the following
criteria: for having no clinical outcome (n = 5), unavailable grouping (n = 15), and
theoretical
research or review (n = 23). Finally, 8 studies were included in the meta-analysis,
with 613 subjects in the UTPA group and 488 subjects in the CTPA group. The selection
process is presented
in [Fig. 1 ].
Fig. 1
The flow chart shows the process for identifying relative studies.
The main characteristics of the included studies are summarized in Table 1, with two
prospective comparative studies, and eight retrospective comparative studies. The
age of patients in the
UTPA group and the CTPA group was more than 60 years. Other basic characteristics
of the included studies are shown in [Table 1 ].
Table 1
The general characteristic of the included studies.
Study
Years
Design
No. of
UTPA
Sample
CTPA
Surgery
Gender
female/male
Age (mean)
Mean follow-up, mo
Yan [9 ]
2014
Prospective
158
151
PKP
220/89
71.9 ± 4.2
16.8
Yan [11 ]
2016
Prospective
55
53
PKP
39/15
68.9 ± 4.2
12
Jia [12 ]
2018
Retrospective
18
18
PVP
30/6
76.2 ± 10.6
18.3
Huang [13 ]
2020
Retrospective
48
47
PKP
80/15
66.91 ± 5.09
6
Lu [14 ]
2020
Retrospective
38
38
PKP
61/15
77.2 ± 3.9
12–24
Tao [15 ]
2021
Retrospective
135
101
PKP
314/133
76.6 ± 7.2
12
Lian [16 ]
2021
Retrospective
31
31
PVP
42/20
65.37 ± 5.14
3
Pan [17 ]
2021
Retrospective
44
49
PKP
57/36
68.8 ± 5.0
15.3
Quality assessment and potential bias
Based on the inclusion and exclusion criteria, eight articles were included in the
meta-analysis. Quality and potential bias were assessed by a funnel plot. The funnel
plot for log WMD in
the bone cement leakage rate of the included studies was notably symmetrical, suggesting
no significant publication bias ([Fig. 2 ]). The results of the methodological quality evaluation showed that one article was
of medium quality and seven articles were of high quality, all of which met the
requirements of the meta-analysis. The specific scores are shown in [Table 2 ].
Fig. 2
Funnel plot to assess publication bias of the bone cement leakage rate.
Table 2
Quality evaluation according to the Newcastle-Ottawa Quality Assessment Scale.
Study
Selection 4
Comparability 2
Exposure 3
Total score 9
Yan [9 ]
4
1
3
8
Yan [11 ]
3
2
3
8
Jia [12 ]
2
2
3
7
Huang [13 ]
4
1
2
7
Lu [14 ]
3
2
3
6
Tao [15 ]
4
1
3
8
Lian [16 ]
2
2
3
7
Pan [17 ]
3
2
3
8
Results of meta-analysis
VAS score
Preoperative VAS scores were compared in six studies (441 patients in the UTPA group
and 404 patients in the CTPA group) without significant heterogeneity (I2 = 0%). The results
showed that there was no statistically significant difference between the preoperative
VAS scores of the two groups (MD = 0.03, 95% CI [–0.12, 0.18], p = 0.68) ([Fig. 3 ]); the two groups were comparable. Five literatures compared postoperative VAS scores
(393 patients in the UTPA group and 357 patients in the CTPA group), showing
heterogeneity (I2 = 72%), so the random effects model was used to the merge data. The results showed
that there was no statistically significant difference in VAS scores between
the two groups (MD = -0.02, 95% CI [0.25, 0.20], p = 0.85) ([Fig. 4 ]). VAS scores at the last follow-up were compared in five studies (403 patients in
the UTPA group and 366 in the CTPA group) with heterogeneity
(I2 = 92%). The results showed that there was no statistically significant difference
in VAS scores between the two groups after data combination using a random effects
model
(MD = 0.24, 95% CI [–0.22, 0.69], p = 0.31) ([Fig. 5 ]), indicating that the puncture method had no significant influence on short-term
and long-term postoperative pain relief.
Fig. 3
Mean difference of preoperative VAS scores between the UTPA group and the CTPA group.
CI = confidence interval, IV = inverse variance, SD = standard deviation.
Fig. 4
Mean difference of postoperative VAS scores between the UTPA group and the CTPA group.
Fig. 5
Mean difference of the VAS scores at the last follow-up between the UTPA group and
the CTPA group.
ODI score
Preoperative ODI scores were compared in four studies (228 patients in the UTPA group
and 199 patients in the CTPA group) without significant heterogeneity (I2 = 17%). The
results showed that there was no statistically significant difference in preoperative
ODI scores between the two groups (MD = –0.71, 95% CI [–1.76, 0.34], p = 0.19) ([Fig. 6 ]), indicating comparability. ODI scores were compared in four studies (228 patients
in the UTPA group and 199 patients in the CTPA group) with significant
heterogeneity (I2 = 90%). The results of the data combination by the random effect model showed that
there was no significant difference in postoperative ODI score between the two
groups [MD = -1.38, 95% CI [–3.90, 1.13], p = 0.28) ([Fig. 7 ]). ODI scores were compared in four studies at the last follow-up (228 patients in
the UTPA group and 199 patients in the CTPA group) with significant heterogeneity
(I2 = 98%). Data were combined by the random effects model and the results showed that
there was no significant difference in postoperative ODI score between the two groups
(MD =
-1.54, 95% CI [–6.02, 2.93], p = 0.50) ([Fig. 8 ]), indicating that there was no significant difference in the impact of the puncture
method on postoperative short-term and long-term spinal function.
Fig. 6
Mean difference of preoperative ODI scores between the two groups.
Fig. 7
Mean difference of postoperative ODI scores between the UTPA group and the CTPA group.
Fig. 8
Mean difference of the ODI scores at the last follow-up between the UTPA group and
the CTPA group.
Kyphosis angle
Preoperative kyphosis angle was compared in six studies (425 patients in the UTPA
group and 470 in the CTPA group) without significant heterogeneity (I2 = 0%). The results showed
that there was no statistically significant difference in the preoperative kyphosis
angle between the two groups (MD = 0.22, 95% CI [–0.12, 0.55], p = 0.20) ([Fig. 9 ]), which was comparable. The postoperative kyphosis angle was compared in six studies
(425 patients in the UTPA group and 470 in the CTPA group) with heterogeneity
(I2 = 78%). The random effects model was used to combine data and the results showed
that there was no significant difference in postoperative kyphosis angle between the
two
groups (MD = –0.79, 95% CI [–1.69, 0.11], p = 0.08) ([Fig. 10 ]). The angles of kyphosis at last follow-up were compared in four studies (369 patients
in the UTPA group and 414 in the CTPA group) without significant
heterogeneity (I2 = 59%). There was no statistically significant difference in the kyphosis angle between
the two groups at the last follow-up (MD = –0.10, 95% CI [–0.52, 0.32],
p = 0.65) ([Fig. 11 ]). The results showed that the puncture method had no significant influence on the
correction of kyphosis.
Fig. 9
Mean difference of the preoperative kyphosis angle between the two groups.
Fig. 10
Mean difference of the postoperative kyphosis angle between the UTPA group and the
CTPA group.
Fig. 11
Mean difference of the kyphosis angle at the last follow-up between the UTPA group
and the CTPA group.
Operative time
Eight studies compared the duration of surgery (527 patients in the UTPA group and
488 patients in the CTPA group) with significant heterogeneity (I2 = 98%). Therefore, the
random effects model was used to combine the data, and the results showed that the
UTPA group took significantly less time than the CTPA group (MD = –12.00, 95% CI [–16.85,
–7.14],
p < 0.001) ([Fig. 12 ]).
Fig. 12
Mean difference of the operative time between the UTPA group and the CTPA group.
Bone cement leakage rate
Bone cement leakage rates were reported in five studies (495 patients in the UTPA
group and 458 patients in the CTPA group) without significant heterogeneity (I2 = 0%). The
results showed that the bone cement leakage rate in the UTPA group was significantly
lower than that in the CTPA group (MD = 0.62, 95% CI [0.42, 0.92], p = 0.02) ([Fig. 13 ]).
Fig. 13
Mean difference of the bone cement leakage rates between the UTPA group and the CTPA
group.
The amount of bone cement
The perfusion dose of bone cement was reported in seven studies (472 patients in the
UTPA group and 435 patients in the CTPA group) with significant heterogeneity (I2 = 98%). The
results showed that there was no significant difference in the perfusion dose of bone
cement between the two groups (MD = -0.62, 95% CI [–1.44, 0.19], p = 0.13) ([Fig. 14 ]).
Fig. 14
Mean difference of the amount of bone cement between the UTPA group and the CTPA group.
X-ray fluoroscopy
The frequency of fluoroscopy was reported in five studies (179 patients in the UTPA
group and 183 patients in the CTPA group), with significant heterogeneity (I2 = 89%). The
random effects model was used to combine data and the results showed that the number
of fluoroscopies in the UTPA group was significantly lower than that in the CTPA group
(MD = –3.73, 95%
CI [–4.44, –3.02], p < 0.001) ([Fig. 15 ]).
Fig. 15
Mean difference of the frequency of fluoroscopy between the UTPA group and the CTPA
group.
Discussion
PVA is widely used in the treatment of painful OVCFs. Traditional unilateral and bilateral
transpedicular approaches provide effective and safe treatment for patients with painful
OVCFs.
However, the operation of a unilateral transpedicular approach often fails to make
bone cement evenly and sympathetically distributed in the affected vertebrae, resulting
in a series of
complications, such as refracture. Therefore, PVA via a bilateral pedicle approach
is more commonly used in clinical practice [18 ]. Different from the traditional transpedicular puncture, a trans transverse process-pedicle
puncture was performed at the midline of the transverse process 1–3 mm outside
the projection edge of the pedicle. According to the segment of the fractured vertebral
body, the entry point of T11-L2 gradually moved outward, and the camber angle of puncture
gradually
increased [19 ]. The new approach is believed to have advantages over traditional methods. As is
known to all, the ideal treatment for OVCF should have a quick and lasting analgesic
effect and can correct kyphosis caused by fracture well and improve quality of life
[20 ]. The results of this study showed that the puncture route had no significant effect
on pain relief, which was reflected not only in short-term pain relief, but also in
long-term pain relief. However, some scholars put forward a different view that the
occurrence of postoperative PVA pain is clearly related to the puncture route. They
suggested that it was
possible that the puncture site of the traditional pedicle approach was closer to
the facet joint, thus damaging the facet joint and causing postoperative low back
pain. Sun et al. [21 ] reported that the unilateral trans transverse process-pedicle approach avoided facet
injury, was more conducive to improving patients’ symptoms and postoperative quality
of life, and the short-term postoperative lumbago pain was significantly better than
a bilateral puncture. However, our study cannot provide sufficient evidence to prove
that PVA therapy for
pain in OVCF patients is related to the puncture route.
In this study, it was found that the unilateral transverse process-pedicle approach
reduced the operation time. The extension of operation time is accompanied by the
increase of anesthetic
maintenance drugs, which increases the risk of perioperative period for patients with
a poor basic state and puts more economic burden on patients. However, in the traditional
pedicle
approach, the operation time with the bilateral approach takes longer than the unilateral
approach, which is consistent with our research conclusions.
Cement leakage is the main complication of OVCF treatment, and this complication is
really related to the puncture technique [22 ]. For the prevention of bone cement leakage, the key lies in the choice of puncture
route and the amount of bone cement infusion dose, which was also proved in our study,
namely, the leakage rate through the unilateral transverse process-vertebral pedicle
approach was significantly lower than that through the traditional bilateral pedicle
approach. In addition,
in our study, there was no significant relationship between the infusion dose of bone
cement and puncture route, which was also consistent with clinical reality. The filling
dose of bone
cement should be more related to the size of the injured vertebra, the viscosity of
bone cement, and the degree of fracture.
Long-term exposure to a large amount of radiation dose seriously harms the health
of medical staff. In this regard, scholars at home and abroad agree that no matter
how much and the duration
of the radiation dose they receive, as long as the accumulated dose exceeds the limit,
there is a risk of inducing diseases [23 ]. The risk of inducing cancer increases by 0.004% for every 1 msV radiation dose
received [24 ]. Percutaneous vertebral augmentation, however, exposes doctors to much higher radiation
doses than other orthopedic procedures. Therefore, this aspect should be paid more
attention. In our study, patients received a significant difference in radiation dose
between traditional and new techniques. Traditional bilateral pedicle puncture results
in patients
receiving significantly more radiation doses than a transversal-pedicle puncture.
Liebschner et al. [25 ], through a three-dimensional finite element study, believed that unilateral puncture
may lead to imbalanced filling of bone cement, thus causing spinal mechanic changes,
and unilateral puncture is inferior to bilateral puncture in restoring vertebral stability.
Although there are still controversies about the clinical efficacy of unilateral and
bilateral
puncture injection of bone cement and the effect of bone cement distribution on spinal
biomechanics, many scholars have realized that once the puncture reaches or passes
through the midline of
the vertebral body and bone cement is distributed to the other side of the vertebral
body, both sides of the vertebral body can be strengthened [26 ]. Wang et al. [27 ] reported that the transverse process-pedicle approach group presented with a more
lateral entry point, larger puncture inclination angles, and higher success rates
than
that in the CTPA group. On the basis of reducing the risk of puncture, the unilateral
transversal-pedicle approach is the best target site for PVA surgery, and bone cement
can be diffused
contralaterally, achieving the same satisfactory clinical results as the bilateral
pedicle approach [28 ]. When performing a puncture operation, the puncture needle should exceed the midline
of the vertebral body to maximize the uniform distribution of bone cement, so as to
restore the height of the vertebral body, correct scoliosis, and reduce the risk of
postoperative vertebral instability, bone cement leakage, and re-collapse of the injured
vertebral body.
It is true that the precise location of the puncture is important in clinical events
but it is all about the refinement of the puncture technique, not the choice of the
puncture site.
Limitation
This study had some limitations. Due to the large inter-study heterogeneity of the
included articles, the sensitivity can only be reduced through the random effect model
in the statistical
analysis so as to reduce a certain risk of bias. In addition, most studies have focused
on pain relief and functional recovery, and complications such as recurrent fractures
have not been
mentioned. Therefore, further high-quality RCTs with a large sample size and long
follow-up duration are warranted to offer more invaluable and convincing conclusions.
Conclusion
This study showed that PVA in both puncture methods relieved pain and significantly
improved quality of life in patients with OVCF. There was no difference in the choice
of surgical
indications between the two methods. The new puncture method does not have any advantages
over the traditional technique, so there is no point in continuing to obsess over
the impact of the
puncture method on surgical outcome. It is definitely important and necessary to carefully
measure and compare imaging data before selecting the best puncture method for each
individual and
vertebral level.
