Keywords kyphoplasty - vertebroplasty - vertebral fracture - osteoporosis
Palavras-chave cifoplastia - vertebroplastia - fratura vertebral - osteoporose
Introduction
It is estimated that 30% of the people over the age of 65 will have a vertebral body
compression fracture caused by osteoporosis.[1 ] Osteoporotic fractures of the spine can lead to chronic pain, progressive deformity,
reduced quality of life, and increased mortality.[1 ]
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Since 1987, bone filling techniques have become progressively widespread, with benefits
in the treatment of pain and associated deformity correction.[5 ] Vertebroplasty was initially introduced as a spinal cementation method for treating
pain and preventing or treating vertebral collapse. Its major drawback is that it
involves the direct injection of cement at high temperatures into the Haversian canals
within the trabecular bone,[5 ] with risk of leakage into the spinal structures, potential damage to the spinal
cord, and paraplegia.[5 ]
[13 ]
[14 ]
[15 ]
[16 ]
[17 ]
[18 ]
[19 ]
[20 ]
Kyphoplasty was developed to address the limitations and risks of vertebroplasty.
The procedure was first performed in 1998, and its goals are similar to those of vertebroplasty.
The technique, based on the principle of coronary stents, consists of placing an inflatable
intravertebral balloon by the percutaneous route. The balloon creates a cavity which
is then filled with cement in the same volume. Although there is an injection of cement
at high temperature under pressure (similarly to vertebroplasty), it is not injected
into the harversian canals but into a created cavity, lowering the risks of leakage.
In addition, the intravertebral balloon can be expanded to restore the vertebral body
height, which is not possible with the vertebroplasty. From a technical standpoint,
kyphoplasty follows almost the same fluoroscopic principles used in vertebroplasty.[21 ]
[22 ]
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The aim of this study is to evaluate the effect of kyphoplasty, compared with that
of vertebroplasty, for the treatment of osteoporotic vertebral fractures, based on
an overview of published reviews.
Methods
This study is a literature review of systematic reviews on the effects of kyphoplasty
compared with vertebroplasty. References were retrieved electronically from the MEDLINE
(via PubMed), Cochrane Database of Systematic Reviews and Google Scholar databases.
Only articles in English were considered. A structured search was conducted using
the PICOT method, as described below:
Participants: Patients with osteoporotic vertebral fractures.
Intervention: Kyphoplasty.
Controls: Vertebroplasty.
Outcomes: All clinically relevant outcomes.
Types of study: Published systematic reviews.
Search query: (“Kyphoplasty” [MeSH Terms] OR “kyphoplasty” [All Fields]) AND “Review” [Publication
Type] - 272
Methodological Quality Assessment
We used the validated measurement tool to assess systematic reviews (AMSTAR) to evaluate
the methodological quality of the retrieved studies.[11 ]
[12 ]
[13 ]
[14 ] This tool consists of 11 questions designed to determine how strictly a systematic
review was conducted. Each answer is assigned a score equivalent to one point per
positive response. Quality is graded as low (0 to 4 points), moderate (5 to 8 points),
or high (9 points or more).[11 ]
[12 ]
[13 ]
[14 ]
Results
Our search strategy yielded 31 records of systematic reviews, selected by title. Among
these, the following reviews were analyzed: three reviews comparing kyphoplasty versus
vertebroplasty versus conservative treatment;[15 ]
[16 ]
[17 ] three reviews comparing kyphoplasty versus conservative treatment;[18 ]
[19 ]
[20 ] and six reviews comparing kyphoplasty and vertebroplasty.[17 ]
[18 ]
[19 ]
[21 ]
[22 ]
[23 ] Head-to-head comparisons of vertebroplasty versus kyphoplasty were the object of
this analysis. Because there was an overlapping of the reviews above mentioned, the
final number of studies evaluated was 9 ([Fig. 1 ] and [Table 1 ]).
Table 1
Summarized data from reviews evaluated in the present manuscript
Author/Year
Liang et al, 2016
Bouza et al, 2006
Taylor et al, 2007
Included studies
32 (4 RCTs)
26
43
Objective
To compare clinical/radiological outcomes and complication of KP/VP.
To analyze the collected body of evidence regarding the efficacy and safety of KP
in the treatment of VCFs.
update of a previous systematic review and meta-analysis of the efficacy and safety
of KP
Clinical outcomes
Short-term and Long-term VAS scores were evaluated. The result showed a significant
difference favoring KP.
Data from comparative studies:
Combined analysis of the studies shows KP to yield a mean reduction in pain intensity
that is 55.6% greater than that afforded by conservative management
The results of a retrospective analysis of KP versus vertebroplasty in tumoral VCFs
show that, globally, no significant differences are found between the two techniques
in terms of pain relief.
Data from comparative studies:
VAS pain was significantly reduced with KP at 3, 6, 12 and 36 months follow up (p < 0.001). These reductions in pain were greater (than those observed at the same
point in time with medical care treatment).
Radiological outcomes
Kyphoplasty resulted more improvement in the kyphotic angle (immediate and final follow-up)
than with the VP procedure
Comparative studies:
KP x VP: KP produces a statistically significant improvement in local kyphosis
Two studies reported improvement in the vertebral height and kyphotic angle with KP
at follow-up. These improvements exceeded those of vertebroplasty
Complications
No significant differences in the rate of postoperative fractures.
Cement leakage to the intraspinal space was more frequently observed in the VP group
(p = 0.35).
Evaluation of the 19 studies that contribute data shows a total of 134 cement leakages
in 1,742 treated levels, out of which only 1.5% are described as symptomatic or cause
clinical sequelae.
Combined analysis of two comparative studies showed that patients subjected to kyphoplasty
are at a significantly lesser risk of suffering new fractures 6 months after the procedure
than patients in the comparator group studies subjected to medical management.
A total of 189 cement leakages were reported in 2,239 vertebrae submitted a KP. This
corresponds to 81 cement leaks per 1,000 fractures undergoing KP per year
KP: A total of 171 new or incident fractures were reported in 1,151 patients across
16 studies, 110 (64%) of which occurred in the vertebrae adjacent to the procedure.
Author/Year
Ma et al, 2012
Papanastassiou et al, 2012
Shi-Ming et al, 2015
Included studies
12 (1 RCT)
27
11
Objective
To evaluate the safety and efficacy of (KP) compared with (VP) and provide recommendations
for using these procedures to treat (VCF).
To determine if differences in safety or efficacy exist between KP, VP and conservative
treatment of osteoporotic vertebral fractures
To determine the efficacy and safety for the treatment of VCFs to reach a relatively
conclusive answer
Clinical outcomes
Long-term VAS scores: the RCT and CCT subgroup analyses found no significant differences
between the KP and VP groups. However, the cohort study subgroup analysis found that
KP was more effective than VP
Pain reduction in both KP and VP was superior to that observed in conservative treatment,
while no difference was found between KP and VP (p = 0.35)
VAS: The short-term subgroup found that KP was more effective than VP, but subgroup
analysis of long-term did not find a significant difference between the VP and KP
groups.
Radiological outcomes
Long-term postoperative kyphosis angles. The RCT and cohort study subgroup analyses
found that the mean long-term kyphosis angle of the KP patients was significantly
smaller than the angle of the VP patients. However, CCT subgroup analysis did not
find a significant difference between the KP and VP patients.
Kyphoplasty resulted in greater kyphosis reduction than VP (4.88 versus 1.7°, P\0.01)
Short-term kyphotic angle: the VP and KP patients did not differ significantly in
the USA subgroup. However, the Europe and Asia subgroups analysis found that KP was
more effective than VP
Complications
The overall pooled analysis of bone cement leakage found a significantly lower rate
in KP patients than in VP patients. However, the CCT subgroup analysis did not find
a significant difference between the KP and VP groups
Adjacent vertebral fracture: there were no significant differences between the KP
and VP patients in any of the subgroups analyzed
Cement extravasation, reported as an event rate, was significantly less frequent for
KP, than for VP.
Subsequent fractures occurred more frequently in the conservative group compared with
VP and KP
Cement leakage: the pooled analysis showed that there was no significant difference
between these two interventions.
Adjacent fractures: these two interventions had similar risk for a subsequent fracture
Author/Year
Robinson et al,2012
Hulme et al, 2006
Stevenson et al, 2014
Included studies
8
69
9 RCTs
Objective
This systematic review analyses randomized controlled trials on VP and KP to provide
an overview on the current evidence
To evaluate the safety and efficacy of VP and KP
To evaluate the clinical effectiveness and cost-effectiveness of VP and KP in reducing
pain and disability in people with VCFs in England and Wales.
Clinical outcomes
All treatment and control groups had significant improvement from baseline to follow-up
at 1, 3, and 12 months
Pooled analyze not described
Visual analog pain scores (VAS) were reduced from an average of 8.2 and 7.15 to 3.0
and 3.4 for vertebroplasty and kyphoplasty, respectively
–
Radiological outcomes
Not evaluated
Mean kyphotic angle restoration was 6.6° and 6.6° for vertebroplasty and kyphoplasty,
respectively. Not all subjects had a reduction in kyphotic angle or restoration of
height (34% and 39% of KP and VP interventions)
Four studies reported changes in BH and/or angular deformity. However, because of
because of heterogeneity, the data was not pooled.
Complications
Not evaluated
Cement leakage occurred for 41% and 9% of treated vertebrae for vertebroplasty and
kyphoplasty, respectively.
New fractures of adjacent vertebrae occurred for both procedures at rates that are
approximately equivalent to the general osteoporotic population that had a previous
vertebral fracture.
Cement leakage: the pooled data suggest an incidence of 44% for VP compared with 27%
for KP
Only three studies reported the number of patients who suffered new radiographic vertebral
fractures during the study period. None of these studies found a statistically significant
difference between treatment groups
Abbreviations: CCT, controlled clinical trial; KP, kyphoplasty; RCT, randomized controlled
trial; VAS, visual analogue scale; VBH, vertebral bone height; VCF, vertebral compression
fractures; VP, vertebroplasty.
Fig. 1 Prisma flow diagram of evaluated studies.
Data Extraction
The latest review was published in 2016,[6 ] and included 4 randomized trials, 14 prospective cohort studies, and 14 retrospective
cohort studies for analysis.[6 ]
The second most recent review[24 ] identified two randomized trials. The study conducted by Bae et al[25 ] used Cortoss (Orthovita, Malvern, PA, USA) cement as the spinal fill method, and
was thus excluded from our analysis, as all other studies used methyl methacrylate
cements.
Wang et al[26 ] identified only one randomized trial.
Taylor et al (2007)[19 ] evaluated five comparative studies, several non-comparative prospective studies,
and no randomized trials.
Hulme et al (2006)[22 ] also did not assess any randomized trial. Most of the analyzed studies were retrospective
(37); 25 were prospective; and did not describe their designs.
Hsieh et al (2013)[27 ] reviewed not only primary studies, but systematic reviews as well.
In 2014, a health technology assessment of percutaneous vertebroplasty and kyphoplasty
was published by a UK group.[23 ] The authors identified nine randomized trials. Out of these, only one (Liu et al)
directly compared kyphoplasty and vertebroplasty.[28 ]
The most complete and current review, which evaluated the largest number of publications,
was conducted by Liang et al.[6 ] All the comparative studies, including 3,274 patients (1,653 undergoing kyphoplasty
and 1,621 undergoing vertebroplasty), were covered in their meta-analysis.[30 ]
[31 ]
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As stated by the current evidence regarding overviews of systematic reviews, it is
possible to choose the last or the best existent review to be used as the main source
for a final review.[11 ]
[12 ]
[13 ]
[14 ] As the revision of Liang et al included all the described studies present in other
revisions, this revision was selected for the data analysis, ensuring that there was
no data duplication. Data are presented in [Table 1 ].
Outcomes
Clinical
Visual Analogue Scale (VAS)
Visual analogue scale at short-term follow-up (less than 1 week of follow-up): Eighteen
studies reported results as weighted mean difference (WMD), with the kyphoplasty group
scoring lower on the pain scale (- 0.2; 95% CI - 0.27 to - 0.63; p < 0.01).[6 ]
[30 ]
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Visual analogue scale (after 6 months of follow-up): This outcome was assessed by
14 studies. Again, the kyphoplasty group had lower scores on the pain scale (- 0.46;
95% CI - 0.57 to - 0.36; p < 0.01).[6 ]
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Oswestry Disability Index (ODI)
The short-term ODI scores were evaluated by 7 studies. The difference between the
kyphoplasty and vertebroplasty groups was significant (- 17.56; 95% CI - 18.07 to
- 17.05; p < 0.01).[6 ]
[18 ]
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Regarding the clinical outcomes of both techniques, the pooled analysis revealed a
statistically significant difference favoring kyphoplasty compared with vertebroplasty
in the short-term and long-term VAS,[6 ] yielding lower scores than vertebroplasty. The difference, however, was insufficient
to achieve clinical benefit. The minimal clinically significant difference in short-term
ODI scores varies in the literature, but 17 points favoring kyphoplasty has been considered
as clinically significant.
Radiological
The height of the anterior third of the vertebral body was evaluated in 14 studies.
On late follow-up, patients undergoing kyphoplasty had a higher standardized average
difference in the vertebral body height (greater correction) (2.79; 95% CI 2.39 to
3.19; p < 0.01).[6 ]
[18 ]
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[63 ]
The height of the middle third of the vertebral body was greater in the kyphoplasty
group, as measured by the standardized mean difference (6.92; 95% CI 6.31 to 7.52;
p < 0.01).[6 ]
[18 ]
[19 ]
[20 ]
[21 ]
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[63 ]
The kyphosis angle in the immediate postoperative period was evaluated in 15 studies,
and showed greater improvement in the kyphoplasty group compared with the vertebroplasty
group (-2.5; 95%CI -2.16 to -2.84; p < 0.01). The kyphotic angle in the late postoperative period was assessed by 9 studies,
and the kyphoplasty group was again superior to the vertebroplasty group.[6 ]
[18 ]
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[63 ] The clinical and radiological outcomes are briefly summarized in [Table 2 ].
Table 2
Clinical and radiological outcomes compared between kyphoplasty (KP) and vertebroplasty
(VP)
Outcome
Result
Statistics
Clinical
VAS
Short term
Kp < VP
p < 0.01
Long term
Kp < VP
p < 0.01
ODI
–
Kp < VP
p < 0.01
Radiological
Height of anterior third of the vertebral body
–
KP > VP
p < 0.01
Height of middle third of the vertebral body
–
KP > VP
p < 0.01
Kyphosis angle
–
KP > VP
p < 0.01
Abbreviations: KP, kyphoplasty; ODI, Oswestry Disability Index; VAS, visual analogue
scale; VP, vertebroplasty.
In all analyzed outcomes, kyphoplasty was superior to vertebroplasty. There were lower
scores in visual analogue scale (VAS) and Oswestry disability index (ODI), and better
increase in the height of vertebral body and in the kyphosis angle.
Complications
Cement leakage into the vertebral canal was less frequent in the kyphoplasty group
than in the vertebroplasty group (OR 0.5; 95% CI 0.3 to 0.85; p = 0.035). Extraspinal leakage was also less frequent with kyphoplasty than with vertebroplasty
(OR 0.36; 95% CI 0.21 to 0.62; p = 0.15).[6 ]
[18 ]
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Adjacent vertebral fractures were reported in 3 studies, with no significant difference
between techniques.[6 ]
[18 ]
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Methodological Quality Assessment of Selected Reviews
The sole review selected for analysis (Liang 2016) was assigned 7 of 11 possible points
on the AMSTAR score, corresponding to a moderate methodological quality.[11 ]
[12 ]
[13 ]
[14 ]
Discussion
Vertebral body fractures secondary to osteoporosis are highly prevalent and cause
significant morbidity. They are associated with chronic pain, progressive deformity,
reduced quality of life, and increased mortality. While treatment can be conservative
or surgical, spinal augmentation techniques play a key role in the management of these
cases, as they are effective and minimally invasive options.[1 ]
[2 ]
[3 ]
[4 ]
[5 ]
[6 ]
[7 ]
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[25 ]
[26 ]
[27 ]
[28 ]
[29 ]
[30 ]
Vertebroplasty was the first vertebral augmentation technique to be implemented. Although
technically effective, it has the drawback of requiring direct injection of cement
at high temperature and pressure directly into the Haversian canal system within the
trabecular bone, with a risk of leakage into the spinal and extraspinal structures.[1 ]
[2 ]
[3 ]
[4 ]
[5 ]
[6 ]
[7 ]
[8 ]
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[29 ]
[30 ] Of particular concern is the possibility of high-temperature cement leakage from
the Haversian canals into the epidural veins. The vertebral venous content oscillates
with the vertebral deformation during the endplate loading. This contributes to the
communication into the vertebral venous plexus and, potentially, a cement leakage
into the vertebral canal and spinal cord injury. Kyphoplasty has the advantage of
using a balloon to create an intraosseous cavity that allows the injection of intracavitary
bone cement with lower leakage risk.[1 ]
[2 ]
[3 ]
[4 ]
[5 ]
[6 ]
[7 ]
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[30 ]
Although there are many studies on these two techniques, there is no consensus in
the literature regarding the superiority of one method over the other. We conducted
a systematic review of literature reviews to synthesize the current concept of their
clinical efficacy.[1 ]
[2 ]
[3 ]
[4 ]
[5 ]
[6 ]
[7 ]
[8 ]
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[11 ]
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[28 ]
[29 ]
[30 ]
In our literature review, we identified three systematic reviews comparing kyphoplasty
versus vertebroplasty versus conservative treatment, all limited to randomized studies.
Only one randomized study comparing both techniques was described.[28 ]
Regarding the clinical outcomes of both techniques, kyphoplasty was superior to vertebroplasty
in short-term and long-term VAS and short-term ODI, yielding lower scores than vertebroplasty.
Pain control was more effective with kyphoplasty.[6 ]
Regarding radiological outcomes, kyphoplasty achieved greater differences in the height
of the anterior third and middle third of the vertebrae, reflecting better reestablishment
of the bone architecture. The kyphotic angles in the immediate and late postoperative
period were also significantly lower in the kyphoplasty group compared with the vertebroplasty
group, which is consistent with greater correction of the deformity.[6 ]
Osteoporotic deformities are another factor that contributes to pain, discomfort,
and impaired quality of life. Promoting optimal correction of the deformity has direct
implications for pain management and spinal sagittal imbalance correction. Kyphoplasty
was superior to vertebroplasty in correcting deformities in the sagittal plane.[6 ]
Cement leakage and adjacent vertebral fractures were evaluated as complications. Leakage
of cement into the vertebral canal and extraspinal spaces was significantly more frequent
in the vertebroplasty than in the kyphoplasty group. Conversely, fractures in the
adjacent vertebral levels were reported in few studies, without evidence of a significant
difference between the techniques.[6 ]
Complications arising from vertebroplasty may be classified as mild (temporary increase
in pain, transient hypotension), moderate (infection, leakage of cement into the foraminal,
epidural, or dural space), or severe (cement leakage into the paravertebral veins,
pulmonary embolism, cardiac perforation, cerebral embolism, or even death). Leakage
of cement into the epidural or foraminal space is considered a rare complication.
However, as most cases are clinically silent, the true prevalence may be as high as
40%. Paraplegia due to a cement-related spinal cord compression may occur in 0.4%
of patients. Needle traversal of laminae instead of the pedicle can occur, especially
in the thoracic vertebrae, where the pedicle is smaller; this can lead to catastrophic
complications.[6 ]
The optimal method should concentrate the deposition of bone cement into the vertebrae,
preferably supporting the middle and anterior thirds of the spinal column, which are
the main sites of bone loss. Furthermore, the ideal method would isolate the cement
from the rich neurovascular structures in the vicinity. In this line, the vertebral
canal and extravertebral cement leakage rates were lower with kyphoplasty than with
vertebroplasty.
Therefore, the current evidence supports that kyphoplasty has superior efficacy in
terms of clinical and radiographic outcomes and is associated with fewer complications
than vertebroplasty.
This study is limited by the absence of a definitive guideline for conducting literature
reviews of systematic reviews. Instead, we modeled our design after suggestions and
published guidelines. Furthermore, we evaluated all the available reviews, but only
the last one (Liang et al) was chosen as a parameter, as it was the most recent and
robust, and it contained all the published studies of interest.
New randomized trials should be encouraged to analyze larger samples of patients and
assess the heterogeneity of effects.
