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Incidence of Cement Leakage Between Unilateral and Bilateral Percutaneous Vertebral Augmentation for Osteoporotic Vertebral Compression Fractures: A Meta-Analysis of Randomized Controlled Trials
Literature Review
Incidence of Cement Leakage Between Unilateral and Bilateral Percutaneous Vertebral Augmentation for Osteoporotic Vertebral Compression Fractures: A Meta-Analysis of Randomized Controlled Trials Weijian Chen1, Weixing Xie2, Zenglin Xiao1, Haoyan Chen1, Daxiang Jin2, Jinyong Ding2
Key words Cement leakage - Meta-analysis - Percutaneous vertebral augmentation -
Abbreviations and Acronyms CI: Confidence interval OVCF: Osteoporotic vertebral compression fracture PKP: Percutaneous kyphoplasty PVA: Percutaneous vertebral augmentation PVP: Percutaneous vertebroplasty RCT: Randomized controlled trial From the 1Guangzhou University of Chinese Medicine, Guangzhou, People’s Republic of China; and 2Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, People’s Republic of China To whom correspondence should be addressed: Daxiang Jin, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2019) 122:342-348. https://doi.org/10.1016/j.wneu.2018.10.143 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2018 Published by Elsevier Inc.
INTRODUCTION Description of the Condition With the aging of society, osteoporotic vertebral compression fracture (OVCF) has become a common disease that threatens the health and the quality of life of older people.1 Percutaneous vertebral augmentation (PVA), including percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP), has been shown to be effective in the treatment of OVCF.2,3 In PVA, the cavity of the collapsed vertebrae is filled with viscous cement such as polymethylmethacrylate. The major complications were related to leakage of the cement beyond the confines of the collapsed vertebral body. Although most leakage was clinically asymptomatic, serious complications occurred in 3.9%e 7.5% of the patients who underwent PVA.4
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- BACKGROUND:
A meta-analysis of randomized controlled trials (RCTs) was performed to compare the incidence of cement leakage between unilateral and bilateral percutaneous vertebral augmentation (PVA) in treating osteoporotic vertebral compression fractures (OVCFs).
- METHODS:
PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials were searched to retrieve the reported data from the establishment of the databases until August 1, 2018. The RCTs on unilateral and bilateral PVA for OVCFs were included. RevMan software, version 5.3, was used for the meta-analysis.
- RESULTS:
Six RCTs were selected from the reported data. The studies included a total of 676 vertebras, 339 of which had received unilateral PVA and the rest, bilateral PVA. The incidence of cement leakage in the unilateral PVA group was less than that in the bilateral PVA group, and the difference between the 2 groups was statistically significant (risk ratio, 0.50; 95% confidence interval, 0.35e0.72; P [ 0.0002). The cement dosage in the unilateral PVA group was less than that in the bilateral PVA group, and the difference between the 2 groups was statistically significant (weighted mean difference, L1.98; 95% confidence interval, L2.24 to L1.72; P < 0.00001). The cement dosage and the incidence of cement leakage in the unilateral PVA group were lower than those in the bilateral PVA group.
- CONCLUSIONS:
The results of our meta-analysis have provided sufficient evidence to show that the unilateral approach can decrease the incidence of cement leakage in PVA. We believe the unilateral approach could reduce the risk of cement leakage owing to the lower cement dosage in the treated vertebra.
Description of the Intervention In the early stages, a bilateral approach was adopted as the standard technique for PVA. However, with the advantages of simple surgery and short operative times, other investigators have acknowledged that unilateral PVA can also achieve the same clinical results. Therefore, the unilateral approach has also been widely accepted in recent years.5,6 Although it has been reported that the unilateral approach could also reduce the possibility of cement leakage through the cannula tract and resulting nerve injury,7,8 a few studies found no statistically significant difference in cement leakage between unilateral and bilateral PVA.1,9 To reduce cement
leakage, it is necessary to ascertain which approach, unilateral and bilateral PVA, is safer. We performed a meta-analysis to evaluate and compare the cement dosage and cement leakage of the unilateral versus the bilateral approach. To the best of our knowledge, no meta-analysis has been reported in which all the included trials were randomized controlled trials (RCTs) and had been written in English.
METHODS Search Strategy PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials were
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Exclusion Criteria Studies were excluded if they met the following criteria. First, the study had not been conducted through a RCT. Second, the report had repeated data from another study. Third, the intervention strategy or control group settings were not in accordance with our selection criteria. Fourth, the study was an animal study, cadaveric study, biomechanical study, review, or case report.
Figure 1. Method used for the literature search. RCT, randomized controlled trial.
searched to retrieve English-language data from the establishment of the databases until August 1, 2018. The keywords included “osteoporotic vertebral compression fractures,” “OVCFs,” “osteoporotic vertebral fractures,” “spinal fractures,” “percutaneous vertebroplasty,” “PVP,” “vertebral plasty,” “cementoplasty,” “percutaneous kyphoplasty,” “PKP,” “percutaneous vertebral augmentation,” “PVA,” “cement leakage,” “cement extravasation, ” “cement volume,” “cement dosage,” “unilateral,” “unipedicular,” “unilaterally,” “bilateral,” “bipedicular,” and “bipediculary.” In addition, the references cited in the reports and reported data from related areas were also checked manually to identify other eligible studies. When required, the authors of the
reports were contacted. All analyses were performed of previously reported studies. Thus, no ethical approval or patient consent was required. Inclusion Criteria Studies were included in our meta-analysis if they met the following criteria. First, the study must have been conducted through a RCT. Second, the included subjects had to have been patients with OVCFs. Third, the study was required to be a comparative study of patients who had undergone unilateral PVA and those who had undergone bilateral PVA. Fourth, the observation indexes were required to be cement leakage or cement volume. Finally, the report had to have been written in English.
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Quality Assessment of Studies Two evaluators independently selected the studies and extracted the data. The data extracted including the following categories: study identification, study design, operative methods, intervention, comparison, number of patients, gender, mean age, number of vertebra, and outcome. Disagreements were resolved through consultation and, if necessary, discrepancies were discussed with a third author. The Cochrane Collaboration risk assessment tool was used to evaluate the level of bias involved in the present study. The RCT bias risk was assessed according to the correctness of the randomization; whether the grouping was confined and correct; whether blinding had been adopted; the completeness of the results; whether the study results had been reported selectively; and whether other potential bias was present. For each criterion, an assessment of “low-degree bias,” “unclear bias,” or “high-degree bias” was given.
Meta-Analysis Methods The RevMan5.3 software program of the Cochrane Collaboration was used to analyze the data. First, the Q test and I2 value calculations were adopted to analyze the heterogeneity of the data. A P value < 0.1 and I2 value >50% indicated a greater level of heterogeneity among the selected studies. If no heterogeneity was found, a fixed effects model was used for analysis. Otherwise, a random effects model was used when significant heterogeneity was found among the included studies. Funnel plots were used to evaluate the publication bias when >10 studies were identified.
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Table 1. Summary of Study Characteristics Included in the Meta-Analysis Investigator
Study Design
Operative Method
Group
Yan et al.,10
RCT
PKP
13
Rebolledo et al., 2013
14
RCT
PKP
Patients (M; F)
Vertebra
Age (Years)
Cement Leakage
Cement Dosage (mL)
Unilateral
158 (46; 112)
158
71.9 4.2
12
3.4 0.8
Bilateral
151 (43; 108)
151
71.1 3.7
22
5.5 0.7
Unilateral
23
28
NR
2
4.8 1.7
Bilateral
21
28
NR
7
6.3 2.4
24
55
NR
3
NR
Chen et al., 2011
RCT
PKP
Unilateral Bilateral
25
59
NR
3
NR
Chen et al.,15 2014
RCT
PKP
Unilateral
20
23
69.43 6.25
9
3.17 1.24
Bilateral
19
21
68.66 8.76
15
4.36 1.14
Unilateral
24 (8; 16)
24
69.2
5
3.1 0.4
Bilateral
26 (10;16)
26
70.5
9
5 0.5
Unilateral
NR
54
NR
4
6.2 0.6
Bilateral
NR
54
NR
10
8.5 0.8
Zhang et al.,
17
16
2015
Yan et al., 2016
RCT
RCT
PVP
PKP
Data presented as number of patients or mean standard deviation. M, male; F, female; RCT, randomized controlled trial; PKP, percutaneous kyphoplasty; NR, not reported; PVP, percutaneous vertebroplasty.
RESULTS Description of Studies The initial search of the reported data produced 235 articles of interest. Of these 235 articles, 95 were subsequently excluded after reading the titles and abstracts because they were duplicates. After reviewing the remaining 140 studies, 132 were excluded because they did not meet our inclusion criteria. Eight full-text RCT studies were retrieved for further assessment, and no articles were excluded because the outcome index did not meet the demand. A total of 8 related RCT studies that satisfied the selection criteria were identified. Two reports10,11 were studies of the same group of subjects. The cement volume was not reported as the mean standard deviation, and no detailed report of cement leakage was provided in 1 study.12 The study selection process is illustrated in Figure 1. Finally, 6 RCT studies10,13-17 were included. Study Characteristics The studies had been reported from 2011 to 2016. A total of 676 vertebrae were included, including 339 unilateral PVAtreated vertebrae and 337 bilateral PVAtreated vertebrae. The unilateral PVA group and bilateral PVA group were well
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matched at baseline according to the information obtained from the studies. One of the 6 studies had used PVP as the operative method,16 and the others had used PKP.10,13-15,17 Details of the included studies are presented in Table 1.
Risk of Bias in Included Studies We used the Cochrane Collaboration tool for assessing the risk of bias to evaluate the risk of bias for the selected articles. The risk of bias was assessed from 6 perspectives. The included studies had all claimed randomization, although only 2 trials10,16 reported concrete methods of
random sequences generation. None of studies described allocation concealment. None of the trials reported blinding of the participants and personnel, and 1 trial16 illustrated blinding of the outcomes assessment. Five selected studies provided the required information and detailed data, and the cement volume was not calculated as the mean standard deviation in 1 trial.14 Because the study protocols were not available, selective reporting was identified as an unclear risk in all included studies. The risk of bias present in the selected studies is shown in Figures 2 and 3.
Figure 2. Risk of bias graph showing a review of our judgments about each risk of bias item presented as percentages across all included studies.
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fixed-effects model showed that the incidence of cement leakage in the unilateral PVA group was less than that in the bilateral PVA group, with a statistically significant difference (risk ratio, 0.50; 95% confidence interval [CI], 0.35e0.72; P ¼ 0.0002; Figure 4). Cement Dosage. Five selected studies10,13,15-17 reported the cement dosage used between unilateral and bilateral PVA. Heterogeneous tests showed moderate heterogeneity among the studies (P ¼ 0.02; I2 ¼ 66%). The results of the random effects model showed that the cement dosage in the unilateral PVA group was less than that in the bilateral PVA group, with a statistically significant difference (mean difference, 1.98; 95% CI, 2.24 to 1.72; P < 0.00001; Figure 5). DISCUSSION
Figure 3. Risk of bias summary showing a review of our judgments about each risk of bias item for each included study.
Research Results Cement Leakage. The 6 selected studies10,13-17 all reported the incidence of cement leakage
between unilateral and bilateral PVA. Heterogeneous tests showed no heterogeneity among the studies (P ¼ 0.97; I2 ¼ 0%). The
OVCFs have always been associated with a poor general condition and thus result in significant morbidity and respiratory complications.18-20 PVA is an effective treatment for patients with OVCF and has been recommended to be performed as early as possible.21 One of the major complications with PVA is cement leakage, with an incidence of 19%e65%.22 Although most cases of cement leakage will be clinically asymptomatic, it is well known that most of the complications stem directly from cement leakage.23 When cement leakage occurred within the disc, the risk of adjacent fracture increased fourfold.24 Cement leakage into the intervertebral disc space has also been reported as a predictive factor affecting the incidence of adjacent vertebral fracture.25 Additionally, cement leakage into the spinal canal can
Figure 4. Forest plot of comparison of the incidence of cement leakage. CI, confidence interval; M-H, Mantel-Haenszel.
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Figure 5. Forest plot of comparison of the cement dosage. CI, confidence interval; M-H, Mantel-Haenszel.
cause canal stenosis and spinal cord compression26 and can result in thermal injury to the neural tissues.27 Also, cement leakage into the intervertebral foramina can lead to nerve root compression.28 Moreover, cement leakage into the perivertebral system and inferior vena cava can result in catastrophic morbidities such as cardiopulmonary arrest,29 acute kidney injury,30 paradoxical embolism through a patent foramen ovale,31 and death.32 Arterial embolization33,34 and cement pulmonary embolism35,36 have also been reported. Some studies have reported that bilateral PVA is superior because of the excellent pain relief, which is associated with symmetrical distribution of bone cement in the vertebral body.37,38 However, recent studies have suggested that unilateral PVA requires less operation time, has limited xray exposure, and minimal cement introduction and extravasation.39 In theory, bilateral PVA not only has an increased incidence of complications, such as tissue trauma, pedicle fracture, and nerve injury,21 but also carries a risk of bone cement leakage that is twice that of unilateral PVA.21 Some clinical studies have shown that the bone cement injection volume has a positive correlation with the leakage of bone cement.40,41 A larger volume of injected cement through the bipedicular approach is also more likely to result in extravasation, which is consistent with our research findings. In our study, the cement dosage and the incidence of cement leakage in the unilateral PVA group were lower than those in the bilateral PVA group. Although Feng et al.42 reported statistically significant differences in the cement leakage rate
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between unilateral and bilateral PVA, a few previous meta-analyses showed that the difference in cement leakage rates between unipedicular and bipedicular PVA was not statistically significant.43,44 We attempted to analyze the reasons for the difference in incidence of cement leakage between our findings and those from previously reported meta-analyses.1,21,45 First, a significant number of trials included in the previous meta-analyses1,21,45 were from Chinese databases, which made it difficult to vouch for the quality of the included data. In addition, the trials by Chen et al.46,47 were often included in a few previous meta-analyses.1,21,45 In fact, the 2 reports46,47 were of the same group of subjects, and we decided that the 2 trials did not meet the criteria of a RCT owing to the lack of random allocation. In their reports,46,47 4 patients in group II were reassigned to group I to meet the patients’ requirement after random allocation. In addition, Feng et al.21 concluded that the risk of cement leakage did not differ between the 2 approaches and that the definition of the unilateral and bilateral approach groups should refer to the number of vertebra, respectively, rather than the number of patients in a forest plot of cement leakage. In summary, various issues were concerning in the previously reported meta-analyses, and we believe that the conclusion from our meta-analysis is more convincing. All the trials included in the present study were RCTs. Combining the results of 6 RCTs, we found that the unilateral approach could decrease the incidence of cement leakage in PVA. However, our research had some limitations. First, the authenticity of our research is dependent
on the selected original reports. The number of the included RCTs was relatively small, and the sample size of most of the included studies was also relatively small. Additionally, only 1 study had adopted PVP as an operative method. These limitations increased the possibility of overestimating the benefits of the unilateral approach. Second, the methods were constrained in most of the included RCTs, which had a negative effect on the authenticity of the results. First, all the included studies had adopted single-center methods and none had adopted multicenter methods. Second, the description of the randomization protocol was not sufficient in 4 of the RCTs.13-15,17 Finally, most had not described the allocation concealment and blinding, and only 1 study14 had reported blinding of the outcomes assessment.
CONCLUSION Overall, the unilateral approach decreased the incidence of cement leakage in the studies selected. More randomized double-blind controlled trials of higher quality are needed to validate the question of the incidence of cement leakage.
ACKNOWLEDGMENTS The first author (Weijian Chen) would like to thank Drs. Jin and Xie for their assistance in editing our report. REFERENCES 1. Cheng X, Long HQ, Xu JH, Huang YL, Li FB. Comparison of unilateral versus bilateral percutaneous kyphoplasty for the treatment of patients with osteoporosis vertebral compression fracture (OVCF): a systematic review and meta-analysis. Eur Spine J. 2016;25:3439-3449.
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2. Garfin SR, Yuan HA, Reiley MA. New technologies in spine: kyphoplasty and vertebroplasty for the treatment of painful osteoporotic compression fractures. Spine (Phila Pa 1976). 2001;26:1511-1555.
15. Chen C, Bian J, Zhang W, Zhang W, Zhao C, Wei H. Unilateral versus bilateral vertebroplasty for severe osteoporotic vertebral compression fractures. J Spinal Disord Techn. 2014;27:E301-E304.
3. Ma X, Xing D, Ma JX, Xu WG, Wang J, Chen Y. Balloon kyphoplasty versus percutaneous vertebroplasty in treating osteoporotic vertebral compression fracture: grading the evidence through a systematic review and meta-analysis. Eur Spine J. 2012;21:1844-1859.
16. Zhang L, Liu Z, Wang J, Feng X, Yang J, Tao Y, et al. Unipedicular versus bipedicular percutaneous vertebroplasty for osteoporotic vertebral compression fractures: a prospective randomized study. BMC Musculoskelet Disord. 2015;16:145.
4. Liang Z, Wang J, Feng X, Tao Y, Yang J, Wang Y, et al. A comparison of high viscosity bone cement and low viscosity bone cement vertebroplasty for severe osteoporotic vertebral compression fractures. Clin Neurol Neurosurg. 2015;129:10-16. 5. Harbour R, Miller J. A new system for grading recommendations in evidence based guidelines. BMJ. 2001;323:334-336. 6. Cho SM, Nam YS, Cho BM, Lee SY, Oh SM, Kim MK. Unilateral extrapedicular vertebroplasty and kyphoplasty in lumbar compression fractures: technique, anatomy and preliminary results. J Korean Neurosurg Soc. 2011;49:273-277. 7. Papadopoulos E, Edobor-Osula FM, Shindle MK, Lane JM. Unipedicular balloon kyphoplasty for the treatment of osteoporotic vertebral compression fractures: early results. J Spinal Disord Techn. 2008; 21:589-596. 8. Lee SB, Cho KS, Huh PW, Yoo DS, Kang SG, Kim DS, et al. Clinical and radiographic results of unilateral transpedicular balloon kyphoplasty for the treatment of osteoporotic vertebral compression fractures. Acta Neurochir Suppl. 2008;101: 157-160. 9. Yang LY, Wang XL, Zhou L, Fu Q. A systematic review and meta-analysis of randomized controlled trials of unilateral versus bilateral kyphoplasty for osteoporotic vertebral compression fractures. Pain Physician. 2013;16:277-290. 10. Yan L, Jiang R, He B, Liu T, Hao D. A comparison between unilateral transverse process-pedicle and bilateral puncture techniques in percutaneous kyphoplasty. Spine (Phil Pa 1976). 2014;39:B19-B26. 11. Hao D, He B, Yan L. A comparison between unilateral transverse process-pedicle and bilateral puncture techniques in percutaneous kyphoplasty. Eur Spine J. 2014;23:S477. 12. Chung HJ, Chung KJ, Yoon HS, Kwon IH. Comparative study of balloon kyphoplasty with unilateral versus bilateral approach in osteoporotic vertebral compression fractures. Int Orthop. 2008; 32:817-820. 13. Rebolledo B, Gladnick B, Unnanuntana A, Nguyen JT, Kepler CK, Lane JM. Comparison of unipedicular and bipedicular balloon kyphoplasty for the treatment of osteoporotic vertebral compression fractures: a prospective randomised study. Bone Joint J. 2013;11:401-406. 14. Chen L, Yang H, Tang T. Unilateral versus bilateral balloon kyphoplasty for multilevel osteoporotic vertebral compression fractures: a prospective study. Spine (Phila Pa 1976). 2011;36: 534-540.
17. Yan L, He B, Guo H, Liu T, Hao D. The prospective self-controlled study of unilateral transverse process-pedicle and bilateral puncture techniques in percutaneous kyphoplasty. Osteoporosis Int. 2015;27:1849-1855. 18. Kim KW, Cho KJ, Kim SW, Lee S-H, An M-H, Im J-H. A nation-wide, outpatient-based survey on the pain, disability, and satisfaction of patients with osteoporotic vertebral compression fractures. Asian Spine J. 2013;7:301-307.
29. Braiteh F, Row M. Right ventricular acrylic cement embolism: late complication of percutaneous vertebroplasty. Heart. 2009;95:275. 30. Chung SE, Lee SH, Kim TH, Yoo KH, Jo BJ. Renal cement embolism during percutaneous vertebroplasty. Eur Spine J. 2006;15:590-594. 31. Scroop R, Eskridge J, Britz GW. Paradoxical cerebral arterial embolization of cement during intraoperative vertebroplasty: case report. AJNR Am J Neuroradiol. 2002;23:868-870. 32. Caynak B, Onan B, Sagbas E, Duran C, Akpinar B. Cardiac tamponade and pulmonary embolism as a complication of percutaneous vertebroplasty. Ann Thorac Surg. 2009;87:299-301. 33. Yazbeck PG, Al Rouhban RB, Slaba SG, Kreichati GE, Kharrat KE. Anterior spinal artery syndrome after percutaneous vertebroplasty. Spine J. 2011;11:e5-e8.
19. Lee YK, Jang S, Jang S, Lee HJ, Park C, Ha YC, et al. Mortality after vertebral fracture in Korea. Osteoporosis Int. 2012;23:1859-1865.
34. Tsai YD, Liliang PC, Chen HJ, Lu K, Liang CL, Wang KW. Anterior spinal artery syndrome following vertebroplasty: a case report. Spine (Phila Pa 1976). 2010;35:E134-E136.
20. Sakuma M, Endo N, Oinuma T, Miyasaka D, Oguma Y, Imao K, et al. Incidence of osteoporotic fractures in Sado, Japan in 2010. J Bone Mineral Metab. 2014;32:200-205.
35. Padovani B, Kasriel O, Brunner P, Peretti-Viton P. Pulmonary embolism caused by acrylic cement: a rare complication of percutaneous vertebroplasty. AJNR Am J Neuroradiol. 1999;20:375-377.
21. Feng H, Huang P, Zhang X, Zheng G, Wang Y. Unilateral versus bilateral percutaneous kyphoplasty for osteoporotic vertebral compression fractures: a systematic review and meta-analysis of RCTs. J Orthop Res. 2015;33:1713-1723. 22. Phillips FM. Minimally invasive treatments of osteoporotic vertebral compression fractures. Spine (Phila Pa 1976). 2003;28(suppl):S45-S53. 23. Li X, Yang H, Tang T, Qian Z, Chen L, Zhang Z. Comparison of kyphoplasty and vertebroplasty for treatment of painful osteoporotic vertebral compression fractures: twelve-month follow-up in a prospective nonrandomized comparative study. J Spinal Disord Techn. 2012;25:142-149. 24. Lin EP, Ekholm S, Hiwatashi A, Westesson PL. Vertebroplasty: cement leakage into the disc increases the risk of new fracture of adjacent vertebral body. AJNR Am J Neuroradiol. 2004;25: 175-180. 25. Rho YJ, Choe WJ, Chun YI. Risk factors predicting the new symptomatic vertebral compression fractures after percutaneous vertebroplasty or kyphoplasty. Eur Spine J. 2012;21:905-911. 26. Teng MMH, Cheng H, Ho DMT, Chang C-Y. Intraspinal leakage of bone cement after vertebroplasty: a report of 3 cases. AJNR Am J Neuroradiol. 2006;27:224-229.
36. Rahimi B, Boroofeh B, Dinparastisaleh R, Nazifi H. Cement pulmonary embolism after percutaneous vertebroplasty in a patient with Cushing’s syndrome: a case report. Respir Med Case Rep. 2018;25:78-85. 37. Cotten A, Dewatre F, Cortet B, Assaker R, Leblond D, Duquesnoy B, et al. Percutaneous vertebroplasty for osteolytic metastases and myeloma: effects of the percentage of lesion filling and the leakage of methyl methacrylate at clinical follow-up. Radiology. 1996;200:525-530. 38. Liebschner MA, Rosenberg WS, Keaveny TM. Effects of bone cement volume and distribution on vertebral stiffness after vertebroplasty. Spine (Phila Pa 1976). 2001;26:1547-1554. 39. Sun H, Li C. Comparison of unilateral and bilateral percutaneous vertebroplasty for osteoporotic vertebral compression fractures: a systematic review and meta-analysis. J Orthop Surg Res. 2016;11:156. 40. Kaufmann TJ, Trout AT, Kallmes DF. The effects of cement volume on clinical outcomes of percutaneous vertebroplasty. AJNR Am J Neuroradiol. 2006;27:1933-1937. 41. Phillips FM, Todd WF, Lieberman I, CampbellHupp M. An in vivo comparison of the potential for extravertebral cement leak after vertebroplasty and kyphoplasty. Spine (Phila Pa 1976). 2002;27: 2173-2178 [discussion: 2178-2179].
27. Lai PL, Tai CL, Chen LH, Nien N-Y. Cement leakage causes potential thermal injury in vertebroplasty. BMC Musculoskel Disord. 2011;12:116.
42. Feng YWH, Chen B. Comparison of unilateral and bilateral percutaneous vertebroplasty for treating aged osteoporotic vertebral compression fractures with local anesthesia. J Clin Exp Med. 2014;13:911-914.
28. Alvarez L, Pérez-Higueras A, Quiñones D, Calvo E, Rossi RE. Vertebroplasty in the treatment of vertebral tumors: postprocedural outcome and quality of life. Eur Spine J. 2003;12:356-360.
43. Wang Z, Wang G, Yang H. Comparison of unilateral versus bilateral balloon kyphoplasty for the treatment of osteoporotic vertebral compression fractures. J Clin Neurosci. 2012;19:723-726.
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44. Li LH, Sun TS, Liu Z, Zhang JZ, Zhang Y, Cai YH, et al. Comparison of unipedicular and bipedicular percutaneous kyphoplasty for treating osteoporotic vertebral compression fractures: a metaanalysis. Chin Med J (Engl). 2013;126:3956-3961. 45. Yang S, Chen C, Wang H, Wu Z, Liu L. A systematic review of unilateral versus bilateral percutaneous vertebroplasty/percutaneous kyphoplasty for osteoporotic vertebral compression fractures. Acta Orthop Traumatol Turc. 2017;51: 290-297. 46. Chen C, Chen L, Gu Y, Xu Y, Liu Y, Bai X, et al. Kyphoplasty for chronic painful osteoporotic
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vertebral compression fractures via unipedicular versus bipedicular approachment: a comparative study in early stage. Injury. 2010;41:356-359. 47. Chen C, Wei H, Zhang W, Gu Y, Tang G, Dong R, et al. Comparative study of kyphoplasty for chronic painful osteoporotic vertebral compression fractures via unipedicular versus bipedicular approach. J Spinal Disord Tech. 2011; 24:E62-E65.
commercial or financial relationships that could be construed as a potential conflict of interest. Received 18 September 2018; accepted 23 October 2018 Citation: World Neurosurg. (2019) 122:342-348. https://doi.org/10.1016/j.wneu.2018.10.143 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2018 Published by Elsevier Inc.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any
WORLD NEUROSURGERY, https://doi.org/10.1016/j.wneu.2018.10.143
Incidence of Cement Leakage Between Unilateral and Bilateral Percutaneous Vertebral Augmentation for Osteoporotic Vertebral Compression Fractures: A Meta-Analysis of Randomized Controlled Trials Weijian Chen1, Weixing Xie2, Zenglin Xiao1, Haoyan Chen1, Daxiang Jin2, Jinyong Ding2
Key words Cement leakage - Meta-analysis - Percutaneous vertebral augmentation -
Abbreviations and Acronyms CI: Confidence interval OVCF: Osteoporotic vertebral compression fracture PKP: Percutaneous kyphoplasty PVA: Percutaneous vertebral augmentation PVP: Percutaneous vertebroplasty RCT: Randomized controlled trial From the 1Guangzhou University of Chinese Medicine, Guangzhou, People’s Republic of China; and 2Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, People’s Republic of China To whom correspondence should be addressed: Daxiang Jin, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2019) 122:342-348. https://doi.org/10.1016/j.wneu.2018.10.143 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2018 Published by Elsevier Inc.
INTRODUCTION Description of the Condition With the aging of society, osteoporotic vertebral compression fracture (OVCF) has become a common disease that threatens the health and the quality of life of older people.1 Percutaneous vertebral augmentation (PVA), including percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP), has been shown to be effective in the treatment of OVCF.2,3 In PVA, the cavity of the collapsed vertebrae is filled with viscous cement such as polymethylmethacrylate. The major complications were related to leakage of the cement beyond the confines of the collapsed vertebral body. Although most leakage was clinically asymptomatic, serious complications occurred in 3.9%e 7.5% of the patients who underwent PVA.4
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- BACKGROUND:
A meta-analysis of randomized controlled trials (RCTs) was performed to compare the incidence of cement leakage between unilateral and bilateral percutaneous vertebral augmentation (PVA) in treating osteoporotic vertebral compression fractures (OVCFs).
- METHODS:
PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials were searched to retrieve the reported data from the establishment of the databases until August 1, 2018. The RCTs on unilateral and bilateral PVA for OVCFs were included. RevMan software, version 5.3, was used for the meta-analysis.
- RESULTS:
Six RCTs were selected from the reported data. The studies included a total of 676 vertebras, 339 of which had received unilateral PVA and the rest, bilateral PVA. The incidence of cement leakage in the unilateral PVA group was less than that in the bilateral PVA group, and the difference between the 2 groups was statistically significant (risk ratio, 0.50; 95% confidence interval, 0.35e0.72; P [ 0.0002). The cement dosage in the unilateral PVA group was less than that in the bilateral PVA group, and the difference between the 2 groups was statistically significant (weighted mean difference, L1.98; 95% confidence interval, L2.24 to L1.72; P < 0.00001). The cement dosage and the incidence of cement leakage in the unilateral PVA group were lower than those in the bilateral PVA group.
- CONCLUSIONS:
The results of our meta-analysis have provided sufficient evidence to show that the unilateral approach can decrease the incidence of cement leakage in PVA. We believe the unilateral approach could reduce the risk of cement leakage owing to the lower cement dosage in the treated vertebra.
Description of the Intervention In the early stages, a bilateral approach was adopted as the standard technique for PVA. However, with the advantages of simple surgery and short operative times, other investigators have acknowledged that unilateral PVA can also achieve the same clinical results. Therefore, the unilateral approach has also been widely accepted in recent years.5,6 Although it has been reported that the unilateral approach could also reduce the possibility of cement leakage through the cannula tract and resulting nerve injury,7,8 a few studies found no statistically significant difference in cement leakage between unilateral and bilateral PVA.1,9 To reduce cement
leakage, it is necessary to ascertain which approach, unilateral and bilateral PVA, is safer. We performed a meta-analysis to evaluate and compare the cement dosage and cement leakage of the unilateral versus the bilateral approach. To the best of our knowledge, no meta-analysis has been reported in which all the included trials were randomized controlled trials (RCTs) and had been written in English.
METHODS Search Strategy PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials were
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Exclusion Criteria Studies were excluded if they met the following criteria. First, the study had not been conducted through a RCT. Second, the report had repeated data from another study. Third, the intervention strategy or control group settings were not in accordance with our selection criteria. Fourth, the study was an animal study, cadaveric study, biomechanical study, review, or case report.
Figure 1. Method used for the literature search. RCT, randomized controlled trial.
searched to retrieve English-language data from the establishment of the databases until August 1, 2018. The keywords included “osteoporotic vertebral compression fractures,” “OVCFs,” “osteoporotic vertebral fractures,” “spinal fractures,” “percutaneous vertebroplasty,” “PVP,” “vertebral plasty,” “cementoplasty,” “percutaneous kyphoplasty,” “PKP,” “percutaneous vertebral augmentation,” “PVA,” “cement leakage,” “cement extravasation, ” “cement volume,” “cement dosage,” “unilateral,” “unipedicular,” “unilaterally,” “bilateral,” “bipedicular,” and “bipediculary.” In addition, the references cited in the reports and reported data from related areas were also checked manually to identify other eligible studies. When required, the authors of the
reports were contacted. All analyses were performed of previously reported studies. Thus, no ethical approval or patient consent was required. Inclusion Criteria Studies were included in our meta-analysis if they met the following criteria. First, the study must have been conducted through a RCT. Second, the included subjects had to have been patients with OVCFs. Third, the study was required to be a comparative study of patients who had undergone unilateral PVA and those who had undergone bilateral PVA. Fourth, the observation indexes were required to be cement leakage or cement volume. Finally, the report had to have been written in English.
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Quality Assessment of Studies Two evaluators independently selected the studies and extracted the data. The data extracted including the following categories: study identification, study design, operative methods, intervention, comparison, number of patients, gender, mean age, number of vertebra, and outcome. Disagreements were resolved through consultation and, if necessary, discrepancies were discussed with a third author. The Cochrane Collaboration risk assessment tool was used to evaluate the level of bias involved in the present study. The RCT bias risk was assessed according to the correctness of the randomization; whether the grouping was confined and correct; whether blinding had been adopted; the completeness of the results; whether the study results had been reported selectively; and whether other potential bias was present. For each criterion, an assessment of “low-degree bias,” “unclear bias,” or “high-degree bias” was given.
Meta-Analysis Methods The RevMan5.3 software program of the Cochrane Collaboration was used to analyze the data. First, the Q test and I2 value calculations were adopted to analyze the heterogeneity of the data. A P value < 0.1 and I2 value >50% indicated a greater level of heterogeneity among the selected studies. If no heterogeneity was found, a fixed effects model was used for analysis. Otherwise, a random effects model was used when significant heterogeneity was found among the included studies. Funnel plots were used to evaluate the publication bias when >10 studies were identified.
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Table 1. Summary of Study Characteristics Included in the Meta-Analysis Investigator
Study Design
Operative Method
Group
Yan et al.,10
RCT
PKP
13
Rebolledo et al., 2013
14
RCT
PKP
Patients (M; F)
Vertebra
Age (Years)
Cement Leakage
Cement Dosage (mL)
Unilateral
158 (46; 112)
158
71.9 4.2
12
3.4 0.8
Bilateral
151 (43; 108)
151
71.1 3.7
22
5.5 0.7
Unilateral
23
28
NR
2
4.8 1.7
Bilateral
21
28
NR
7
6.3 2.4
24
55
NR
3
NR
Chen et al., 2011
RCT
PKP
Unilateral Bilateral
25
59
NR
3
NR
Chen et al.,15 2014
RCT
PKP
Unilateral
20
23
69.43 6.25
9
3.17 1.24
Bilateral
19
21
68.66 8.76
15
4.36 1.14
Unilateral
24 (8; 16)
24
69.2
5
3.1 0.4
Bilateral
26 (10;16)
26
70.5
9
5 0.5
Unilateral
NR
54
NR
4
6.2 0.6
Bilateral
NR
54
NR
10
8.5 0.8
Zhang et al.,
17
16
2015
Yan et al., 2016
RCT
RCT
PVP
PKP
Data presented as number of patients or mean standard deviation. M, male; F, female; RCT, randomized controlled trial; PKP, percutaneous kyphoplasty; NR, not reported; PVP, percutaneous vertebroplasty.
RESULTS Description of Studies The initial search of the reported data produced 235 articles of interest. Of these 235 articles, 95 were subsequently excluded after reading the titles and abstracts because they were duplicates. After reviewing the remaining 140 studies, 132 were excluded because they did not meet our inclusion criteria. Eight full-text RCT studies were retrieved for further assessment, and no articles were excluded because the outcome index did not meet the demand. A total of 8 related RCT studies that satisfied the selection criteria were identified. Two reports10,11 were studies of the same group of subjects. The cement volume was not reported as the mean standard deviation, and no detailed report of cement leakage was provided in 1 study.12 The study selection process is illustrated in Figure 1. Finally, 6 RCT studies10,13-17 were included. Study Characteristics The studies had been reported from 2011 to 2016. A total of 676 vertebrae were included, including 339 unilateral PVAtreated vertebrae and 337 bilateral PVAtreated vertebrae. The unilateral PVA group and bilateral PVA group were well
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matched at baseline according to the information obtained from the studies. One of the 6 studies had used PVP as the operative method,16 and the others had used PKP.10,13-15,17 Details of the included studies are presented in Table 1.
Risk of Bias in Included Studies We used the Cochrane Collaboration tool for assessing the risk of bias to evaluate the risk of bias for the selected articles. The risk of bias was assessed from 6 perspectives. The included studies had all claimed randomization, although only 2 trials10,16 reported concrete methods of
random sequences generation. None of studies described allocation concealment. None of the trials reported blinding of the participants and personnel, and 1 trial16 illustrated blinding of the outcomes assessment. Five selected studies provided the required information and detailed data, and the cement volume was not calculated as the mean standard deviation in 1 trial.14 Because the study protocols were not available, selective reporting was identified as an unclear risk in all included studies. The risk of bias present in the selected studies is shown in Figures 2 and 3.
Figure 2. Risk of bias graph showing a review of our judgments about each risk of bias item presented as percentages across all included studies.
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fixed-effects model showed that the incidence of cement leakage in the unilateral PVA group was less than that in the bilateral PVA group, with a statistically significant difference (risk ratio, 0.50; 95% confidence interval [CI], 0.35e0.72; P ¼ 0.0002; Figure 4). Cement Dosage. Five selected studies10,13,15-17 reported the cement dosage used between unilateral and bilateral PVA. Heterogeneous tests showed moderate heterogeneity among the studies (P ¼ 0.02; I2 ¼ 66%). The results of the random effects model showed that the cement dosage in the unilateral PVA group was less than that in the bilateral PVA group, with a statistically significant difference (mean difference, 1.98; 95% CI, 2.24 to 1.72; P < 0.00001; Figure 5). DISCUSSION
Figure 3. Risk of bias summary showing a review of our judgments about each risk of bias item for each included study.
Research Results Cement Leakage. The 6 selected studies10,13-17 all reported the incidence of cement leakage
between unilateral and bilateral PVA. Heterogeneous tests showed no heterogeneity among the studies (P ¼ 0.97; I2 ¼ 0%). The
OVCFs have always been associated with a poor general condition and thus result in significant morbidity and respiratory complications.18-20 PVA is an effective treatment for patients with OVCF and has been recommended to be performed as early as possible.21 One of the major complications with PVA is cement leakage, with an incidence of 19%e65%.22 Although most cases of cement leakage will be clinically asymptomatic, it is well known that most of the complications stem directly from cement leakage.23 When cement leakage occurred within the disc, the risk of adjacent fracture increased fourfold.24 Cement leakage into the intervertebral disc space has also been reported as a predictive factor affecting the incidence of adjacent vertebral fracture.25 Additionally, cement leakage into the spinal canal can
Figure 4. Forest plot of comparison of the incidence of cement leakage. CI, confidence interval; M-H, Mantel-Haenszel.
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Figure 5. Forest plot of comparison of the cement dosage. CI, confidence interval; M-H, Mantel-Haenszel.
cause canal stenosis and spinal cord compression26 and can result in thermal injury to the neural tissues.27 Also, cement leakage into the intervertebral foramina can lead to nerve root compression.28 Moreover, cement leakage into the perivertebral system and inferior vena cava can result in catastrophic morbidities such as cardiopulmonary arrest,29 acute kidney injury,30 paradoxical embolism through a patent foramen ovale,31 and death.32 Arterial embolization33,34 and cement pulmonary embolism35,36 have also been reported. Some studies have reported that bilateral PVA is superior because of the excellent pain relief, which is associated with symmetrical distribution of bone cement in the vertebral body.37,38 However, recent studies have suggested that unilateral PVA requires less operation time, has limited xray exposure, and minimal cement introduction and extravasation.39 In theory, bilateral PVA not only has an increased incidence of complications, such as tissue trauma, pedicle fracture, and nerve injury,21 but also carries a risk of bone cement leakage that is twice that of unilateral PVA.21 Some clinical studies have shown that the bone cement injection volume has a positive correlation with the leakage of bone cement.40,41 A larger volume of injected cement through the bipedicular approach is also more likely to result in extravasation, which is consistent with our research findings. In our study, the cement dosage and the incidence of cement leakage in the unilateral PVA group were lower than those in the bilateral PVA group. Although Feng et al.42 reported statistically significant differences in the cement leakage rate
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between unilateral and bilateral PVA, a few previous meta-analyses showed that the difference in cement leakage rates between unipedicular and bipedicular PVA was not statistically significant.43,44 We attempted to analyze the reasons for the difference in incidence of cement leakage between our findings and those from previously reported meta-analyses.1,21,45 First, a significant number of trials included in the previous meta-analyses1,21,45 were from Chinese databases, which made it difficult to vouch for the quality of the included data. In addition, the trials by Chen et al.46,47 were often included in a few previous meta-analyses.1,21,45 In fact, the 2 reports46,47 were of the same group of subjects, and we decided that the 2 trials did not meet the criteria of a RCT owing to the lack of random allocation. In their reports,46,47 4 patients in group II were reassigned to group I to meet the patients’ requirement after random allocation. In addition, Feng et al.21 concluded that the risk of cement leakage did not differ between the 2 approaches and that the definition of the unilateral and bilateral approach groups should refer to the number of vertebra, respectively, rather than the number of patients in a forest plot of cement leakage. In summary, various issues were concerning in the previously reported meta-analyses, and we believe that the conclusion from our meta-analysis is more convincing. All the trials included in the present study were RCTs. Combining the results of 6 RCTs, we found that the unilateral approach could decrease the incidence of cement leakage in PVA. However, our research had some limitations. First, the authenticity of our research is dependent
on the selected original reports. The number of the included RCTs was relatively small, and the sample size of most of the included studies was also relatively small. Additionally, only 1 study had adopted PVP as an operative method. These limitations increased the possibility of overestimating the benefits of the unilateral approach. Second, the methods were constrained in most of the included RCTs, which had a negative effect on the authenticity of the results. First, all the included studies had adopted single-center methods and none had adopted multicenter methods. Second, the description of the randomization protocol was not sufficient in 4 of the RCTs.13-15,17 Finally, most had not described the allocation concealment and blinding, and only 1 study14 had reported blinding of the outcomes assessment.
CONCLUSION Overall, the unilateral approach decreased the incidence of cement leakage in the studies selected. More randomized double-blind controlled trials of higher quality are needed to validate the question of the incidence of cement leakage.
ACKNOWLEDGMENTS The first author (Weijian Chen) would like to thank Drs. Jin and Xie for their assistance in editing our report. REFERENCES 1. Cheng X, Long HQ, Xu JH, Huang YL, Li FB. Comparison of unilateral versus bilateral percutaneous kyphoplasty for the treatment of patients with osteoporosis vertebral compression fracture (OVCF): a systematic review and meta-analysis. Eur Spine J. 2016;25:3439-3449.
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commercial or financial relationships that could be construed as a potential conflict of interest. Received 18 September 2018; accepted 23 October 2018 Citation: World Neurosurg. (2019) 122:342-348. https://doi.org/10.1016/j.wneu.2018.10.143 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2018 Published by Elsevier Inc.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any
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