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Single-balloon versus double-balloon bipedicular kyphoplasty for osteoporotic vertebral compression fractures
Journal of Clinical Neuroscience 22 (2015) 680–684
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Clinical Study
Single-balloon versus double-balloon bipedicular kyphoplasty for osteoporotic vertebral compression fractures Heng Wang a, Zhenzhong Sun b, Zhiwen Wang a, Weimin Jiang a,⇑ a b
Orthopedics Department, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Soochow 215006, China Orthopedics Department, The Ninth People’s Hospital of Wuxi, Wuxi, China
a r t i c l e
i n f o
Article history: Received 20 July 2014 Accepted 15 October 2014
Keywords: Bipedicular Kyphoplasty Osteoporosis Vertebral compression fracture
a b s t r a c t Twenty-eight patients with osteoporotic vertebral compression fractures (OVCF) were treated with single-balloon bipedicular kyphoplasty (Group A), and 40 patients were treated with double-balloon bipedicular kyphoplasty (Group B). Visual Analogue Scale (VAS) score, vertebral height, and kyphotic angle (KA) were evaluated pre-operatively, post-operatively (3 days after surgery) and at final followup. Operative time, X-ray exposure frequency and costs were recorded. The mean operative time and X-ray exposure frequency in Group A were greater than in Group B (p < 0.05). Significant improvement of the VAS score was noted in each group, and remained unchanged at final follow-up. Mean increases of anterior and middle height of the fractured vertebral body were 5.14 mm and 4.14 mm in Group A, respectively, and 6.22 mm and 5.06 mm in Group B, respectively, and the differences between the groups were statistically significant (p < 0.05). Mean reduction of KA was 6.9° in Group A and 8.8° in Group B, which was statistically significant (p < 0.05). No statistically significant difference was observed in terms of cement leakage between groups. The mean cost of Group A (US$4202) was significantly less than that of Group B (US$6220) (p < 0.001). Single-balloon bipedicular kyphoplasty is a safe and cost-effective surgical method for the treatment of OVCF. It can achieve pain relief comparable with double-balloon bipedicular kyphoplasty. However, double-balloon bipedicular kyphoplasty is more efficacious in terms of the restoration of vertebral height and reduction of KA, and the operative time and X-ray exposure frequency are lower. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Osteoporotic vertebral compression fractures (OVCF) are common in the elderly, affecting around 1.4 million people each year [1]. Conservative management consists of bed rest, pain relievers, bracing, and physical therapy, but some fractures develop into a progressive deformity and cause debilitating pain [2,3]. Open surgery poses a significant risk in these patients, most of whom are elderly and frail and have only weak bone to support the instrumentation [4,5]. Kyphoplasty is a safe and effective procedure used to treat painful vertebral compression fractures [6]. It uses a balloon, also referred to as an inflatable bone tamp, to create a cavity in the fractured vertebral body into which bone cement is deposited. Traditionally, the standard technique for kyphoplasty consists of cannulating both pedicles and placing two balloons into the ⇑ Corresponding author. Tel.: +86 512 6778 0111; fax: +86 512 6522 8072. E-mail address: [email protected] (W. Jiang). http://dx.doi.org/10.1016/j.jocn.2014.10.014 0967-5868/Ó 2014 Elsevier Ltd. All rights reserved.
vertebral body (double-balloon bipedicular kyphoplasty), and both balloons are inflated simultaneously for en masse reduction [7]. However, bipedicular kyphoplasty with a single balloon (singleballoon bipedicular kyphoplasty) is also applied in clinical settings to reduce the financial cost to patients. To our knowledge, there have been no thorough studies that compare the two techniques of bipedicular kyphoplasty in the treatment of OVCF. The purpose of this study is to retrospectively evaluate and compare the clinical and radiological outcomes of bipedicular kyphoplasty with a single balloon and double balloons for OVCF. 2. Materials and methods 2.1. Study population This study included 68 patients with a single-level osteoporotic compression fracture at the thoracic and lumbar vertebrae (T6–L4) who underwent bipedicular kyphoplasty between January 2011 and October 2012.
H. Wang et al. / Journal of Clinical Neuroscience 22 (2015) 680–684
This study was approved by the Ethics Committee of the First Affiliated Hospital of Soochow University, and written informed consent was obtained from all patients. Inclusion criteria were (1) pain lasting less than 3 months, (2) a pain region consistent with the presence of edema in the fractured vertebra found on MRI, and (3) a Visual Analogue Scale (VAS) score of five or above. Exclusion criteria were (1) a pathologic compression fracture, (2) neurologic deficits, (3) spinal cord compression syndrome, (4) previous spinal surgery, and (5) significant scoliosis. The 68 patients were divided into two groups according to the surgical procedure: Group A (single-balloon group, who received singleballoon bipedicular kyphoplasty) and Group B (double-balloon group, who received double-balloon bipedicular kyphoplasty). Group A consisted of 28 patients (11 male and 17 female) with a mean age of 68.0 ± standard deviation (SD) of 7.7 years (range 56–81). Group B consisted of 40 patients (16 male and 24 female) with a mean age of 69.6 ± SD 9.4 years (range 55–83). There were no significant differences between the two groups regarding demographic data, as shown in Table 1. 2.2. Surgical technique The operations were performed by the same senior surgeon (W.J.). All bipedicular kyphoplasty procedures were performed under general anesthesia using fluoroscopic guidance. Patients were placed in the prone position with a bolster placed under the sternum and pelvis. Double-balloon bipedicular kyphoplasty was performed as previously described [7]. Briefly, this procedure involves inserting KyphX Inflatable Bone Tamps (Kyphon, Sunnyvale, CA, USA) bilaterally into the fractured vertebral body. The balloons are simultaneously and slowly inflated to elevate the endplate, reduce the fracture, and create a cavity. The balloons are deflated and withdrawn, and the resulting cavity is filled with polymethylmethacrylate (PMMA) cement. In single-balloon bipedicular kyphoplasty, the single balloon is inserted into the vertebra through the working channel of one side, inflated, deflated and withdrawn, then inserted into the vertebra through the contralateral working channel. PMMA cement is then injected incrementally into the resulting cavity. 2.3. Data collection and outcome assessment Patients’ demographic data including age, sex, body weight, height and bone mineral density were recorded before surgery. Operative time, cement volume, and exposure time to the C-arm machine were recorded during the operation. We recorded clinical and radiological evaluations pre-operatively, post-operatively (3 days after surgery), and at final follow-up. Pain was evaluated using a VAS, with 0 = no pain and 10 = the worst pain imaginable. The anterior and middle heights of the fractured vertebra were defined as the distance between the superior and inferior endplates of the anterior vertebral wall and the center of the vertebra, respectively [8]. The kyphotic angle (KA) was
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measured as the intersection angle of the inferior end plate and the superior end plate of the fractured vertebral body (Fig. 1). KA reduction was calculated by subtracting the post-operative KA from the pre-operative KA [9]. From the anteroposterior projection, four points were handselected and marked on fractured vertebra (Fig. 2). Points a and b were placed at the most right-superior and left-superior endplate margins, respectively. Points c and d were placed at the most right-inferior and left-inferior endplate margins, respectively. To determine whether lateral wedging occurred, the absolute value of the difference between the measurements of lines ac and bd were compared post-operatively. The outcome of cement leakage was assessed after surgery using radiographs and CT scans. The costs of the two procedures were recorded in US dollars. 2.4. Statistical analysis Data were presented as mean ± SD. The Statistical Package for the Social Sciences software (version 16.0, SPSS, Chicago, IL, USA) was used for the analysis. Intergroup comparisons were made using t-test or chi-squared test. Comparisons of clinical and radiological outcomes pre and post-operatively were made using a paired t-test. Differences were considered statistically significant when p < 0.05. 3. Results All 68 patients tolerated the operation well. The average operative time was 55 ± 13 minutes in Group A and 49 ± 9 minutes in Group B (p = 0.033). The average cement volume was 4.75 ± 1.07 ml in Group A and 5.31 ± 1.05 ml in Group B (p = 0.037) (Table 2). Patients were exposed to X-rays 64 ± 11 times in Group A and 55 ± 16 times in Group B, and this difference was statistically significant (p = 0.012). There was a mean difference of US$2018 in material operative costs between the two procedures, with a mean cost of US$4202 ± 133 in Group A and US$6220 ± 148 in Group B (p < 0.001) (Table 2). The mean follow-up was 17.7 ± 2.7 months for Group A and 18.7 ± 3.1 months for Group B. Both groups experienced excellent pain relief. The VAS score decreased significantly in both groups, from a pre-operative value of 8.0 ± 1.7 to a post-operative value of 2.3 ± 1.5 in Group A (p < 0.001), and from 7.8 ± 1.8 to 2.4 ± 1.2 in Group B (p < 0.001). The VAS score decreased further to 1.9 ± 1.8 and 2.1 ± 1.1 at final follow-up in Group A and Group B, respectively (Table 3). There was no significant difference in post-operative VAS scores between the two groups (p > 0.05). Significant increases of the anterior and middle vertebral heights were observed after surgery and the vertebral heights were maintained throughout the follow-up period in both groups (Table 3). Mean increases of anterior and middle height of the fractured vertebral body was 5.14 mm and 4.14 mm in Group A, respectively, and 6.22 mm and 5.06 mm in Group B, respectively,
Table 1 Pre-operative demographic data of patients undergoing single-balloon (Group A) and double-balloon (Group B) bipedicular kyphoplasty
Patients (n) Male: Female Age, years (range) Fracture age, days (range) T-score Visual Analogue Scale score Kyphotic angle
Group A
Group B
p value
28 11:17 68.0 ± 7.7 (56–81) 32.3 ± 14.0 (7–55) –3.22 ± 0.48 8.0 ± 1.7 19.5 ± 5.8°
40 16:24 69.6 ± 9.4 (55–83) 33.2 ± 17.2 (7–60) –3.36 ± 0.55 7.8 ± 1.8 20.7 ± 4.8°
– – 0.457 0.819 0.279 0.514 0.354
Data are presented as mean ± standard deviation unless otherwise indicated.
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H. Wang et al. / Journal of Clinical Neuroscience 22 (2015) 680–684
Fig. 1. Lateral radiograph showing evaluation of kyphotic angle (KA).
Fig. 2. Anteroposterior radiograph showing evaluation of lateral wedging.
Table 2 Operative data and costs of patients undergoing single-balloon (Group A) and doubleballoon (Group B) bipedicular kyphoplasty
Operative time, minutes X-ray exposure Cement volume, ml Costs, US$
Group A
Group B
p value
55 ± 13 64 ± 11 4.75 ± 1.07 $4202 ± 133
49 ± 9 55 ± 16 5.31 ± 1.05 $6220 ± 148
0.033 0.012 0.037 <0.001
Data are presented as mean ± standard deviation.
with statistically significant differences between the two groups (p = 0.036 and p = 0.044, respectively). Mean reduction of KA was 6.9 ± 3.4° and 8.8 ± 3.0° in Group A and Group B, respectively, which was statistically significant (p = 0.020). In Group A, the difference between the right and left height measurements of the vertebral bodies was 1.80 ± 1.17 mm. In Group B, it was 1.46 ± 0.85 mm. The result shows no significant statistical difference between the two groups (p = 0.191).
The leakage rate of bone cement was 10.7% (3/28) in Group A and 10.0% (4/40) in Group B, which was not significantly different (p = 0.613) (Table 4). One patient in Group A and two in Group B had leakage of the bone cement into the intervertebral disc, which was not significantly different (p = 0.633). In Group A, bone cement leakage into the spinal canal occurred in two patients. In Group B, bone cement leaked into paravertebral veins in one patient, and leaked out lateral to the vertebral body in another. No leakages had any apparent clinical consequences, and no patients developed neurologic symptoms. During the follow-up period, five patients (two in Group A, three in Group B) developed one new symptomatic vertebral compression fracture and underwent an additional kyphoplasty to relieve pain. 4. Discussion Kyphoplasty has proved its merits in the treatment of OVCF, with minimal invasion, rapid pain relief, safe cement augmentation and the capacity to restore vertebral height [10]. Generally, the
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H. Wang et al. / Journal of Clinical Neuroscience 22 (2015) 680–684 Table 3 Mean improvement of clinical and radiographic data of patients undergoing single-balloon (Group A) and double-balloon (Group B) bipedicular kyphoplasty Anterior vertebral height, mm
Middle vertebral height, mm
Kyphotic angle (°)
Pre-op
Pre-op
Pre-op
Post-op
Final
Post-op
Final
Post-op
Visual Analogue Scale score Final
Pre-op
Post-op
Final
Group A 17.54 ± 4.52 22.68 ± 5.12* 21.79 ± 5.24à 18.58 ± 4.20 22.72 ± 4.79* 22.39 ± 4.88à 19.5 ± 5.8 12.6 ± 4.4* 13.1 ± 4.8à 8.0 ± 1.7 2.3 ± 1.5* 1.9 ± 1.8à Group B 19.00 ± 4.31 25.22 ± 4.91* 24.60 ± 4.84à 19.67 ± 5.57 24.74 ± 5.90* 24.60 ± 5.96à 20.7 ± 4.8 12.0 ± 3.4* 12.3 ± 3.5à 7.8 ± 1.8 2.4 ± 1.2* 2.1 ± 1.1à Data are presented as mean ± standard deviation. * Post-operative compared with pre-operative, p < 0.05. à Final compared with pre-operative, p < 0.05. Group A compared with Group B, p > 0.05. post-op = post-operative, pre-op = pre-operative.
bipedicular approach with two balloons is applied to achieve en masse reduction [7]. To achieve en masse reduction as well as to reduce the procedure costs, we performed bipedicular kyphoplasty using a single balloon. In the present study, no significant lateral wedging associated with single-balloon bipedicular kyphoplasty was found, indicating that single-balloon bipedicular kyphoplasty could provide en masse reduction. Although both groups gained significant vertebral height increases and KA reduction, the results showed that double-balloon bipedicular kyphoplasty is more efficacious in restoration of anterior and middle vertebral height and reduction of KA. It can be speculated that, during the process of simultaneous inflation in doubleballoon bipedicular kyphoplasty, the balloons pushed each other in the transverse direction, and then may have inflated further in the vertical direction, achieving better deformity correction. The causes of pain in OVCF are multifactorial, due mainly to micro-movement of the vertebral fracture [11]. Effective pain reduction and satisfactory clinical outcomes can be obtained after elimination of the microfractures and vertebral stabilization. It has been reported that the clinical results of kyphoplasty are not always positively correlated with restoration of height and reduction of the KA [12,13]. In the present study, clinical outcomes were nearly identical for patients undergoing single-balloon versus double-balloon bipedicular kyphoplasty. In this study, asymptomatic cement extravasation occurred in an average of 10.3% (7/68) of the vertebrae treated (3/28 in Group A, 4/40 in Group B), similar to the 9% reported for all bipedicular kyphoplasties in the literature review study of Hulme et al. [14] One noteworthy problem is whether the sequential inflation in single-balloon bipedicular kyphoplasty increases the risk of endplate breakage. It can cause leakage of cement into the intervertebral disc, which is almost always asymptomatic at short-term or midterm follow-up [15]. However, it may increase the risk of fracture of adjacent vertebral bodies due to increased mechanical pressure from the cement [15,16]. The present study showed that the leakage of cement into the intervertebral disc was not significantly different between the two groups. Recently, a few clinical studies have reported that unipedicular kyphoplasty can safely and effectively treat OVCF and the outcomes are comparably satisfactory to bipedicular treatment [2,3,17,18]. It is believed that the presence of cement across the vertebral midline is essential for unipedicular kyphoplasty. Liebschner et al. emphasized that although unipedicular cement distributions exhibited a comparative stiffness to the bipedicular
Table 4 Cement leakage and refracture rates of patients undergoing single-balloon (Group A) and double-balloon (Group B) bipedicular kyphoplasty
Cement leakage Disc leakage Refracture
Group A
Group B
p value
10.7% (3/28) 3.6% (1/28) 7.1% (2/28)
10.0% (4/40) 5% (2/40) 7.5 (3/40)
0.613 0.633 0.667
cases, it led to the unilateral loading of the vertebra, and, consequently, spine instability [19]. Chen et al., in a cadaveric study, also demonstrated that if bone cement is augmented on only one side, the stiffness of the non-augmented side will be significantly lower than the augmented side, which might lead to an imbalance of stress on the vertebrae and subsequently to a wedging or collapse of the biomechanically weaker side [10]. We consider that if the surgeon is unsatisfied with the balloon position or the extent of balloon inflation or cavity created in the procedure of unipedicular kyphoplasty, single-balloon bipedicular kyphoplasty can be a remedy. The limitations of our study are the small number of patients and relatively short-term follow-up. A further limitation of this study was its retrospective nature. Thus, further large-scale prospective randomized controlled trials of single-balloon bipedicular kyphoplasty with long-term follow-up are required. In conclusion, single-balloon bipedicular kyphoplasty is a safe and cost-effective surgical method for the treatment of OVCF; it can achieve satisfactory pain comparable to double-balloon bipedicular kyphoplasty. However, double-balloon bipedicular kyphoplasty is more efficacious in terms of the restoration of vertebral height and reduction of kyphotic angle, and the operative time and X-ray exposure frequency are lower. Conflicts of Interest/Disclosures The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication. Acknowledgements We are very grateful to Professor Huilin Yang for his valuable suggestions on this work. References [1] Johnell O, Kanis JA. An estimate of the worldwide prevalence and disability associated with osteoporotic fractures. Osteoporos Int 2006;17:1726–33. [2] 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;36:534–40. [3] Chung HJ, Chung KJ, Yoon HS, et al. Comparative study of balloon kyphoplasty with unilateral versus bilateral approach in osteoporotic vertebral compression fractures. Int Orthop 2008;32:817–20. [4] Wang G, Yang H, Chen K. Osteoporotic vertebral compression fractures with an intravertebral cleft treated by percutaneous balloon kyphoplasty. J Bone Joint Surg Br 2010;92:1553–7. [5] Itshayek E, Miller P, Barzilay Y, et al. Vertebral augmentation in the treatment of vertebral compression fractures: review and new insights from recent studies. J Clin Neurosci 2012;19:786–91. [6] Wardlaw D, Cummings SR, Van Meirhaeghe J, et al. Efficacy and safety of balloon kyphoplasty compared with non-surgical care for vertebral compression fracture (FREE): a randomised controlled trial. Lancet 2009;373:1016–24. [7] 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;26:1511–5. [8] McKiernan F, Faciszewski T, Jensen R. Reporting height restoration in vertebral compression fractures. Spine (Phila Pa 1976) 2003;28:2517–21 [discussion 3].
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[9] Keynan O, Fisher CG, Vaccaro A, et al. Radiographic measurement parameters in thoracolumbar fractures: a systematic review and consensus statement of the spine trauma study group. Spine (Phila Pa 1976) 2006;31:E156–165. [10] Chen B, Li Y, Xie D, et al. Comparison of unipedicular and bipedicular kyphoplasty on the stiffness and biomechanical balance of compression fractured vertebrae. Eur Spine J 2011;20:1272–80. [11] Barr JD, Barr MS, Lemley TJ, et al. Percutaneous vertebroplasty for pain relief and spinal stabilization. Spine (Phila Pa 1976) 2000;25:923–8. [12] Berlemann U, Franz T, Orler R, et al. Kyphoplasty for treatment of osteoporotic vertebral fractures: a prospective non-randomized study. Eur Spine J 2004;13:496–501. [13] Li X, Yang H, Tang T, et al. Comparison of kyphoplasty and vertebroplasty for treatment of painful osteoporotic vertebral compression fractures: twelvemonth follow-up in a prospective nonrandomized comparative study. J Spinal Disord Tech 2012;25:142–9. [14] Hulme PA, Krebs J, Ferguson SJ, et al. Vertebroplasty and kyphoplasty: a systematic review of 69 clinical studies. Spine (Phila Pa 1976) 2006;31:1983–2001.
[15] Deramond H, Depriester C, Galibert P, et al. Percutaneous vertebroplasty with polymethylmethacrylate. Technique, indications, and results. Radiol Clin North Am 1998;36:533–46. [16] Lin EP, Ekholm S, Hiwatashi A, et al. Vertebroplasty: cement leakage into the disc increases the risk of new fracture of adjacent vertebral body. AJNR Am J Neuroradiol 2004;25:175–80. [17] Rebolledo BJ, Gladnick BP, Unnanuntana A, et al. Comparison of unipedicular and bipedicular balloon kyphoplasty for the treatment of osteoporotic vertebral compression fractures: a prospective randomised study. Bone Joint J 2013;95B:401–6. [18] Papadopoulos EC, Edobor-Osula F, Gardner MJ, et al. Unipedicular balloon kyphoplasty for the treatment of osteoporotic vertebral compression fractures: early results. J Spinal Disord Tech 2008;21:589–96. [19] Liebschner MA, Rosenberg WS, Keaveny TM. Effects of bone cement volume and distribution on vertebral stiffness after vertebroplasty. Spine (Phila Pa 1976) 2001;26:1547–54.
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Clinical Study
Single-balloon versus double-balloon bipedicular kyphoplasty for osteoporotic vertebral compression fractures Heng Wang a, Zhenzhong Sun b, Zhiwen Wang a, Weimin Jiang a,⇑ a b
Orthopedics Department, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Soochow 215006, China Orthopedics Department, The Ninth People’s Hospital of Wuxi, Wuxi, China
a r t i c l e
i n f o
Article history: Received 20 July 2014 Accepted 15 October 2014
Keywords: Bipedicular Kyphoplasty Osteoporosis Vertebral compression fracture
a b s t r a c t Twenty-eight patients with osteoporotic vertebral compression fractures (OVCF) were treated with single-balloon bipedicular kyphoplasty (Group A), and 40 patients were treated with double-balloon bipedicular kyphoplasty (Group B). Visual Analogue Scale (VAS) score, vertebral height, and kyphotic angle (KA) were evaluated pre-operatively, post-operatively (3 days after surgery) and at final followup. Operative time, X-ray exposure frequency and costs were recorded. The mean operative time and X-ray exposure frequency in Group A were greater than in Group B (p < 0.05). Significant improvement of the VAS score was noted in each group, and remained unchanged at final follow-up. Mean increases of anterior and middle height of the fractured vertebral body were 5.14 mm and 4.14 mm in Group A, respectively, and 6.22 mm and 5.06 mm in Group B, respectively, and the differences between the groups were statistically significant (p < 0.05). Mean reduction of KA was 6.9° in Group A and 8.8° in Group B, which was statistically significant (p < 0.05). No statistically significant difference was observed in terms of cement leakage between groups. The mean cost of Group A (US$4202) was significantly less than that of Group B (US$6220) (p < 0.001). Single-balloon bipedicular kyphoplasty is a safe and cost-effective surgical method for the treatment of OVCF. It can achieve pain relief comparable with double-balloon bipedicular kyphoplasty. However, double-balloon bipedicular kyphoplasty is more efficacious in terms of the restoration of vertebral height and reduction of KA, and the operative time and X-ray exposure frequency are lower. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Osteoporotic vertebral compression fractures (OVCF) are common in the elderly, affecting around 1.4 million people each year [1]. Conservative management consists of bed rest, pain relievers, bracing, and physical therapy, but some fractures develop into a progressive deformity and cause debilitating pain [2,3]. Open surgery poses a significant risk in these patients, most of whom are elderly and frail and have only weak bone to support the instrumentation [4,5]. Kyphoplasty is a safe and effective procedure used to treat painful vertebral compression fractures [6]. It uses a balloon, also referred to as an inflatable bone tamp, to create a cavity in the fractured vertebral body into which bone cement is deposited. Traditionally, the standard technique for kyphoplasty consists of cannulating both pedicles and placing two balloons into the ⇑ Corresponding author. Tel.: +86 512 6778 0111; fax: +86 512 6522 8072. E-mail address: [email protected] (W. Jiang). http://dx.doi.org/10.1016/j.jocn.2014.10.014 0967-5868/Ó 2014 Elsevier Ltd. All rights reserved.
vertebral body (double-balloon bipedicular kyphoplasty), and both balloons are inflated simultaneously for en masse reduction [7]. However, bipedicular kyphoplasty with a single balloon (singleballoon bipedicular kyphoplasty) is also applied in clinical settings to reduce the financial cost to patients. To our knowledge, there have been no thorough studies that compare the two techniques of bipedicular kyphoplasty in the treatment of OVCF. The purpose of this study is to retrospectively evaluate and compare the clinical and radiological outcomes of bipedicular kyphoplasty with a single balloon and double balloons for OVCF. 2. Materials and methods 2.1. Study population This study included 68 patients with a single-level osteoporotic compression fracture at the thoracic and lumbar vertebrae (T6–L4) who underwent bipedicular kyphoplasty between January 2011 and October 2012.
H. Wang et al. / Journal of Clinical Neuroscience 22 (2015) 680–684
This study was approved by the Ethics Committee of the First Affiliated Hospital of Soochow University, and written informed consent was obtained from all patients. Inclusion criteria were (1) pain lasting less than 3 months, (2) a pain region consistent with the presence of edema in the fractured vertebra found on MRI, and (3) a Visual Analogue Scale (VAS) score of five or above. Exclusion criteria were (1) a pathologic compression fracture, (2) neurologic deficits, (3) spinal cord compression syndrome, (4) previous spinal surgery, and (5) significant scoliosis. The 68 patients were divided into two groups according to the surgical procedure: Group A (single-balloon group, who received singleballoon bipedicular kyphoplasty) and Group B (double-balloon group, who received double-balloon bipedicular kyphoplasty). Group A consisted of 28 patients (11 male and 17 female) with a mean age of 68.0 ± standard deviation (SD) of 7.7 years (range 56–81). Group B consisted of 40 patients (16 male and 24 female) with a mean age of 69.6 ± SD 9.4 years (range 55–83). There were no significant differences between the two groups regarding demographic data, as shown in Table 1. 2.2. Surgical technique The operations were performed by the same senior surgeon (W.J.). All bipedicular kyphoplasty procedures were performed under general anesthesia using fluoroscopic guidance. Patients were placed in the prone position with a bolster placed under the sternum and pelvis. Double-balloon bipedicular kyphoplasty was performed as previously described [7]. Briefly, this procedure involves inserting KyphX Inflatable Bone Tamps (Kyphon, Sunnyvale, CA, USA) bilaterally into the fractured vertebral body. The balloons are simultaneously and slowly inflated to elevate the endplate, reduce the fracture, and create a cavity. The balloons are deflated and withdrawn, and the resulting cavity is filled with polymethylmethacrylate (PMMA) cement. In single-balloon bipedicular kyphoplasty, the single balloon is inserted into the vertebra through the working channel of one side, inflated, deflated and withdrawn, then inserted into the vertebra through the contralateral working channel. PMMA cement is then injected incrementally into the resulting cavity. 2.3. Data collection and outcome assessment Patients’ demographic data including age, sex, body weight, height and bone mineral density were recorded before surgery. Operative time, cement volume, and exposure time to the C-arm machine were recorded during the operation. We recorded clinical and radiological evaluations pre-operatively, post-operatively (3 days after surgery), and at final follow-up. Pain was evaluated using a VAS, with 0 = no pain and 10 = the worst pain imaginable. The anterior and middle heights of the fractured vertebra were defined as the distance between the superior and inferior endplates of the anterior vertebral wall and the center of the vertebra, respectively [8]. The kyphotic angle (KA) was
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measured as the intersection angle of the inferior end plate and the superior end plate of the fractured vertebral body (Fig. 1). KA reduction was calculated by subtracting the post-operative KA from the pre-operative KA [9]. From the anteroposterior projection, four points were handselected and marked on fractured vertebra (Fig. 2). Points a and b were placed at the most right-superior and left-superior endplate margins, respectively. Points c and d were placed at the most right-inferior and left-inferior endplate margins, respectively. To determine whether lateral wedging occurred, the absolute value of the difference between the measurements of lines ac and bd were compared post-operatively. The outcome of cement leakage was assessed after surgery using radiographs and CT scans. The costs of the two procedures were recorded in US dollars. 2.4. Statistical analysis Data were presented as mean ± SD. The Statistical Package for the Social Sciences software (version 16.0, SPSS, Chicago, IL, USA) was used for the analysis. Intergroup comparisons were made using t-test or chi-squared test. Comparisons of clinical and radiological outcomes pre and post-operatively were made using a paired t-test. Differences were considered statistically significant when p < 0.05. 3. Results All 68 patients tolerated the operation well. The average operative time was 55 ± 13 minutes in Group A and 49 ± 9 minutes in Group B (p = 0.033). The average cement volume was 4.75 ± 1.07 ml in Group A and 5.31 ± 1.05 ml in Group B (p = 0.037) (Table 2). Patients were exposed to X-rays 64 ± 11 times in Group A and 55 ± 16 times in Group B, and this difference was statistically significant (p = 0.012). There was a mean difference of US$2018 in material operative costs between the two procedures, with a mean cost of US$4202 ± 133 in Group A and US$6220 ± 148 in Group B (p < 0.001) (Table 2). The mean follow-up was 17.7 ± 2.7 months for Group A and 18.7 ± 3.1 months for Group B. Both groups experienced excellent pain relief. The VAS score decreased significantly in both groups, from a pre-operative value of 8.0 ± 1.7 to a post-operative value of 2.3 ± 1.5 in Group A (p < 0.001), and from 7.8 ± 1.8 to 2.4 ± 1.2 in Group B (p < 0.001). The VAS score decreased further to 1.9 ± 1.8 and 2.1 ± 1.1 at final follow-up in Group A and Group B, respectively (Table 3). There was no significant difference in post-operative VAS scores between the two groups (p > 0.05). Significant increases of the anterior and middle vertebral heights were observed after surgery and the vertebral heights were maintained throughout the follow-up period in both groups (Table 3). Mean increases of anterior and middle height of the fractured vertebral body was 5.14 mm and 4.14 mm in Group A, respectively, and 6.22 mm and 5.06 mm in Group B, respectively,
Table 1 Pre-operative demographic data of patients undergoing single-balloon (Group A) and double-balloon (Group B) bipedicular kyphoplasty
Patients (n) Male: Female Age, years (range) Fracture age, days (range) T-score Visual Analogue Scale score Kyphotic angle
Group A
Group B
p value
28 11:17 68.0 ± 7.7 (56–81) 32.3 ± 14.0 (7–55) –3.22 ± 0.48 8.0 ± 1.7 19.5 ± 5.8°
40 16:24 69.6 ± 9.4 (55–83) 33.2 ± 17.2 (7–60) –3.36 ± 0.55 7.8 ± 1.8 20.7 ± 4.8°
– – 0.457 0.819 0.279 0.514 0.354
Data are presented as mean ± standard deviation unless otherwise indicated.
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Fig. 1. Lateral radiograph showing evaluation of kyphotic angle (KA).
Fig. 2. Anteroposterior radiograph showing evaluation of lateral wedging.
Table 2 Operative data and costs of patients undergoing single-balloon (Group A) and doubleballoon (Group B) bipedicular kyphoplasty
Operative time, minutes X-ray exposure Cement volume, ml Costs, US$
Group A
Group B
p value
55 ± 13 64 ± 11 4.75 ± 1.07 $4202 ± 133
49 ± 9 55 ± 16 5.31 ± 1.05 $6220 ± 148
0.033 0.012 0.037 <0.001
Data are presented as mean ± standard deviation.
with statistically significant differences between the two groups (p = 0.036 and p = 0.044, respectively). Mean reduction of KA was 6.9 ± 3.4° and 8.8 ± 3.0° in Group A and Group B, respectively, which was statistically significant (p = 0.020). In Group A, the difference between the right and left height measurements of the vertebral bodies was 1.80 ± 1.17 mm. In Group B, it was 1.46 ± 0.85 mm. The result shows no significant statistical difference between the two groups (p = 0.191).
The leakage rate of bone cement was 10.7% (3/28) in Group A and 10.0% (4/40) in Group B, which was not significantly different (p = 0.613) (Table 4). One patient in Group A and two in Group B had leakage of the bone cement into the intervertebral disc, which was not significantly different (p = 0.633). In Group A, bone cement leakage into the spinal canal occurred in two patients. In Group B, bone cement leaked into paravertebral veins in one patient, and leaked out lateral to the vertebral body in another. No leakages had any apparent clinical consequences, and no patients developed neurologic symptoms. During the follow-up period, five patients (two in Group A, three in Group B) developed one new symptomatic vertebral compression fracture and underwent an additional kyphoplasty to relieve pain. 4. Discussion Kyphoplasty has proved its merits in the treatment of OVCF, with minimal invasion, rapid pain relief, safe cement augmentation and the capacity to restore vertebral height [10]. Generally, the
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H. Wang et al. / Journal of Clinical Neuroscience 22 (2015) 680–684 Table 3 Mean improvement of clinical and radiographic data of patients undergoing single-balloon (Group A) and double-balloon (Group B) bipedicular kyphoplasty Anterior vertebral height, mm
Middle vertebral height, mm
Kyphotic angle (°)
Pre-op
Pre-op
Pre-op
Post-op
Final
Post-op
Final
Post-op
Visual Analogue Scale score Final
Pre-op
Post-op
Final
Group A 17.54 ± 4.52 22.68 ± 5.12* 21.79 ± 5.24à 18.58 ± 4.20 22.72 ± 4.79* 22.39 ± 4.88à 19.5 ± 5.8 12.6 ± 4.4* 13.1 ± 4.8à 8.0 ± 1.7 2.3 ± 1.5* 1.9 ± 1.8à Group B 19.00 ± 4.31 25.22 ± 4.91* 24.60 ± 4.84à 19.67 ± 5.57 24.74 ± 5.90* 24.60 ± 5.96à 20.7 ± 4.8 12.0 ± 3.4* 12.3 ± 3.5à 7.8 ± 1.8 2.4 ± 1.2* 2.1 ± 1.1à Data are presented as mean ± standard deviation. * Post-operative compared with pre-operative, p < 0.05. à Final compared with pre-operative, p < 0.05. Group A compared with Group B, p > 0.05. post-op = post-operative, pre-op = pre-operative.
bipedicular approach with two balloons is applied to achieve en masse reduction [7]. To achieve en masse reduction as well as to reduce the procedure costs, we performed bipedicular kyphoplasty using a single balloon. In the present study, no significant lateral wedging associated with single-balloon bipedicular kyphoplasty was found, indicating that single-balloon bipedicular kyphoplasty could provide en masse reduction. Although both groups gained significant vertebral height increases and KA reduction, the results showed that double-balloon bipedicular kyphoplasty is more efficacious in restoration of anterior and middle vertebral height and reduction of KA. It can be speculated that, during the process of simultaneous inflation in doubleballoon bipedicular kyphoplasty, the balloons pushed each other in the transverse direction, and then may have inflated further in the vertical direction, achieving better deformity correction. The causes of pain in OVCF are multifactorial, due mainly to micro-movement of the vertebral fracture [11]. Effective pain reduction and satisfactory clinical outcomes can be obtained after elimination of the microfractures and vertebral stabilization. It has been reported that the clinical results of kyphoplasty are not always positively correlated with restoration of height and reduction of the KA [12,13]. In the present study, clinical outcomes were nearly identical for patients undergoing single-balloon versus double-balloon bipedicular kyphoplasty. In this study, asymptomatic cement extravasation occurred in an average of 10.3% (7/68) of the vertebrae treated (3/28 in Group A, 4/40 in Group B), similar to the 9% reported for all bipedicular kyphoplasties in the literature review study of Hulme et al. [14] One noteworthy problem is whether the sequential inflation in single-balloon bipedicular kyphoplasty increases the risk of endplate breakage. It can cause leakage of cement into the intervertebral disc, which is almost always asymptomatic at short-term or midterm follow-up [15]. However, it may increase the risk of fracture of adjacent vertebral bodies due to increased mechanical pressure from the cement [15,16]. The present study showed that the leakage of cement into the intervertebral disc was not significantly different between the two groups. Recently, a few clinical studies have reported that unipedicular kyphoplasty can safely and effectively treat OVCF and the outcomes are comparably satisfactory to bipedicular treatment [2,3,17,18]. It is believed that the presence of cement across the vertebral midline is essential for unipedicular kyphoplasty. Liebschner et al. emphasized that although unipedicular cement distributions exhibited a comparative stiffness to the bipedicular
Table 4 Cement leakage and refracture rates of patients undergoing single-balloon (Group A) and double-balloon (Group B) bipedicular kyphoplasty
Cement leakage Disc leakage Refracture
Group A
Group B
p value
10.7% (3/28) 3.6% (1/28) 7.1% (2/28)
10.0% (4/40) 5% (2/40) 7.5 (3/40)
0.613 0.633 0.667
cases, it led to the unilateral loading of the vertebra, and, consequently, spine instability [19]. Chen et al., in a cadaveric study, also demonstrated that if bone cement is augmented on only one side, the stiffness of the non-augmented side will be significantly lower than the augmented side, which might lead to an imbalance of stress on the vertebrae and subsequently to a wedging or collapse of the biomechanically weaker side [10]. We consider that if the surgeon is unsatisfied with the balloon position or the extent of balloon inflation or cavity created in the procedure of unipedicular kyphoplasty, single-balloon bipedicular kyphoplasty can be a remedy. The limitations of our study are the small number of patients and relatively short-term follow-up. A further limitation of this study was its retrospective nature. Thus, further large-scale prospective randomized controlled trials of single-balloon bipedicular kyphoplasty with long-term follow-up are required. In conclusion, single-balloon bipedicular kyphoplasty is a safe and cost-effective surgical method for the treatment of OVCF; it can achieve satisfactory pain comparable to double-balloon bipedicular kyphoplasty. However, double-balloon bipedicular kyphoplasty is more efficacious in terms of the restoration of vertebral height and reduction of kyphotic angle, and the operative time and X-ray exposure frequency are lower. Conflicts of Interest/Disclosures The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication. Acknowledgements We are very grateful to Professor Huilin Yang for his valuable suggestions on this work. References [1] Johnell O, Kanis JA. An estimate of the worldwide prevalence and disability associated with osteoporotic fractures. Osteoporos Int 2006;17:1726–33. [2] 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;36:534–40. [3] Chung HJ, Chung KJ, Yoon HS, et al. Comparative study of balloon kyphoplasty with unilateral versus bilateral approach in osteoporotic vertebral compression fractures. Int Orthop 2008;32:817–20. [4] Wang G, Yang H, Chen K. Osteoporotic vertebral compression fractures with an intravertebral cleft treated by percutaneous balloon kyphoplasty. J Bone Joint Surg Br 2010;92:1553–7. [5] Itshayek E, Miller P, Barzilay Y, et al. Vertebral augmentation in the treatment of vertebral compression fractures: review and new insights from recent studies. J Clin Neurosci 2012;19:786–91. [6] Wardlaw D, Cummings SR, Van Meirhaeghe J, et al. Efficacy and safety of balloon kyphoplasty compared with non-surgical care for vertebral compression fracture (FREE): a randomised controlled trial. Lancet 2009;373:1016–24. [7] 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;26:1511–5. [8] McKiernan F, Faciszewski T, Jensen R. Reporting height restoration in vertebral compression fractures. Spine (Phila Pa 1976) 2003;28:2517–21 [discussion 3].
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