Therapeutic efficacy of Transpedicular Intracorporeal cement augmentation with short segmental posterior instrumentation in treating osteonecrosis of the vertebral body: a retrospective case series with a minimum 5-year follow-up.

BACKGROUND: Transpedicular intracorporeal cement augmentation (TCA) with short segmental posterior instrumentation (SSPI), which provides an ideal immediate analgesic effect and long-term reconstructive stability, is thought to be a sensible advancement to the operative strategy in treating osteonecrosis of the vertebral body (ONV). However, long-term follow-up studies about the treatment are scarce. METHODS: Forty-six ONV patients (22 males and 24 females, mean age of 62.8 ± 7.11 years) underwent TCA with SSPI were retrospectively analyzed. During follow-up, clinical outcomes, such as the Visual Analogue Scale (VAS) score and the Oswestry Disability Index (ODI) score, were evaluated, as well as radiologic outcomes, such as the average vertebral height and kyphotic angle. RESULTS: A total of 36 patients completed a follow-up period of at least 5 years (mean follow-up period of 67 ± 4.2 months). Among them, seven patients experienced complications, i.e., pneumonia (2/36, 5.56%), screw loosening (2/36, 5.56%), moderate hematoma in the subcutaneous tissue (1/36, 2.78%), and cement leakage (2/36, 5.56%). Compared to the preoperative score, the mean VAS score was significantly reduced 6 months postoperatively (P < 0.05), and it concluded being virtually identical to the preoperative score (P > 0.05). The mean ODI score exhibited a comparable trend. Regarding the radiologic evaluation, the mean kyphotic angle and average vertebral body height were significantly corrected postoperatively (both P < 0.05). However, these radiological parameters were maximally ameliorated during the direct postoperative period and slowly deteriorated over time. CONCLUSION: The present study shows that TCA with SSPI may be only mildly effective for symptom relief and correction of kyphotic deformity during a relatively long follow-up, thus we do not recommend it for ONV.

Unilateral curved versus bipedicular vertebroplasty in the treatment of osteoporotic vertebral compression fractures.

BACKGROUND: Vertebral compression fracture is one of the most common complications of osteoporosis. In this study an unilateral curved vertebroplasty device was developed, and the safety, effectiveness, and surgical parameters of curved vertebroplasty (CVP) in the treatment of painful osteoporotic vertebral compression fractures was investigated and compared with traditional bipedicular vertebroplasty (BVP). METHODS: We investigated 104 vertebral augmentation procedures performed over 36 months. CVP and BVP procedures were compared for baseline clinical variables, pain relief (Visual Analog Scale, VAS), disability improvement (Oswestry Disability Index, ODI), operation time, number of fluoroscopic images, volume of cement per level, and cement leakage rate for each level treated. Complications and refracture incidence were also recorded in the two groups. RESULTS: The VAS and ODI in both group had no significant difference preoperative (P > 0.05), and a significant postoperative improvement in the VAS scores and ODI was found in both group (P < 0.001). However, the CVP group had significantly lower operation time, number of fluoroscopic images, and cement leakage rate per level than the BVP group (P < 0.05); however, the volumes of cement per level were similar in the two groups (P > 0.05). Neither group had any serious complications. Five and two patients in the BVP group developed refractures at non-adjacent and adjacent levels, respectively, with one patient developing refractures twice; however, none of the patients in the CVP group developed refractures at any level. CONCLUSIONS: Our findings revealed that both CVP and BVP were safe and effective treatments for osteoporotic vertebral compression fractures, and CVP entails a shorter operation time, less exposure to fluoroscopy, and lower rate of cement leakage.

Injectable, biomechanically robust, biodegradable and osseointegrative bone cement for percutaneous kyphoplasty and vertebroplasty.

PURPOSE: Poly(methyl methacrylate) (PMMA) cement is widely used for percutaneous kyphoplasty and vertebroplasty (PKP and PVP) but possesses formidable shortcomings due to non-degradability. Here, a biodegradable replacement is developed. METHODS: Calcium phosphate cement (CPC) was redesigned by incorporating starch and BaSO4 (new cement named as CPB). The biomechanical, biocompatibility, osseointegrative and handling properties of CPB were systematically evaluated in vitro and in vivo by the models of osteoporotic sheep vertebra, rat subcutaneous implantation and rat femoral defect. RESULTS: CPB revealed appropriate injectability and setting ability for PKP and PVP. More importantly, its biomechanical strengths measured by in vitro and in vivo models were not less than that of PMMA, while its biodegradability and osseointegrative capacities were significantly enhanced compared to PMMA. CONCLUSIONS: CPB is injectable, biomechanically robust, biodegradable and osseointegrative, demonstrating revolutionary potential for the application in PKP and PVP.

Modification of PMMA vertebroplasty cement for reduced stiffness by addition of normal saline: a material properties evaluation.

PURPOSE: Vertebral augmentation is an established treatment for patients with pathological vertebral compression fractures. These procedures typically employ a PMMA-based bone cement, which possesses a high compressive stiffness. Because of the increased risk of subsequent fractures after vertebral augmentations, there is a desire for reducing this stiffness. The goal of our study was to examine the influence of adding isotonic saline on the biomechanical properties of PMMA vertebroplasty cement. METHODS: A PMMA-based vertebroplasty cement was prepared according to the manufacturer's recommendations after which isotonic saline was mixed into the cement at 10, 20, and 30% (volume:volume). Testing bodies were cast, and compression and bending tests were performed. Fracture surfaces were studied using SEM. Measurements of injectability, setting temperature, and radioopacity were also performed. RESULTS: The addition of saline solution (of up to vol-30%) led to a pronounced reduction in the compression modulus of the cement from 3409 ± 312 to 1131 ± 127 MPa. In parallel, maximal compression strength was reduced from 86 ± 4 to 33 ± 3 MPa and bending strength from 40 ± 4 to 24 ± 3 MPa. The differences regarding injectability, setting temperature, and radioopacity were small and probably of no clinical relevance. CONCLUSIONS: The compressive stiffness of PMMA-based vertebroplasty cement can be reduced to almost a third by the addition of saline. The probable explanation is an increase in microporosity. Future simulator experiments will show whether the achieved reduction in stiffness is large enough to reduce the rate of subsequent vertebral fractures.

Diagnosis of painful cemented vertebrae from failed vertebroplasty: modified dynamic radiographs play an important role.

PURPOSE: The diagnosis of painful cemented vertebrae resulting from failed PV is not clearly defined in literature. This report evaluates the effectiveness of modified dynamic radiographs in diagnosing painful cemented vertebrae resulting from failed PV. METHODS: From January 2011 to June 2015, 345 patients with a total of 399 VCFs underwent PV at our institution. Among the 345 patients, 27 patients underwent repeated PV at the cemented vertebrae because of persisting or recurrent pain after vertebroplasty. The prevertebroplasty examinations included routine radiographs, modified dynamic radiographs, and MRI. Kyphotic angles and the anterior vertebral body height (AVBH) were measured. The image findings in routine radiographs, modified dynamic radiographs, and MRI were compared. Finally, a visual analog scale was used to measure the outcome. RESULTS: The patients ranged in age from 67 to 90 years. MRI revealed a moderate amount of fluid (definite diagnosis of refracture) in the cemented vertebrae in seven patients, bone edema without fluid in nine patients, and bone edema with minimal fluid in ten patients. The rate of diagnosis of painful cemented vertebrae according to MRI was 27% (7/26). The difference in the kyphotic angle between sitting and supine cross-table lateral radiographs was -9.36° ± 5.20° (P < 0.001). The difference in AVBH was 8.08 ± 3.21 mm (P < 0.001). All 27 patients were confirmed to have dynamic mobility according to the modified dynamic radiographs. CONCLUSIONS: When the diagnosis of painful cemented vertebrae is questionable, modified dynamic radiographs can help diagnose painful cemented vertebrae resulting from failed PV.

[Cement augmentation of pedicle screws : Pros and cons]. / Zementaugmentation von Pedikelschrauben : Vorteile und Nachteile.

Cement augmentation of pedicle screws biomechanically increases screw purchase in the bone. However, clinical complications may occur. The pros and cons of the technique are discussed from different clinical perspectives.

[Cement augmentation on the spine : Biomechanical considerations]. / Zementaugmentation an der Wirbelsäule : Was ist biomechanisch zu beachten?

BACKGROUND: Vertebral compression fractures are the most common osteoporotic fractures. Since the introduction of vertebroplasty and screw augmentation, the management of osteoporotic fractures has changed significantly. AIMS: The biomechanical characteristics of the risk of adjacent fractures and novel treatment modalities for osteoporotic vertebral fractures, including pure cement augmentation by vertebroplasty, and cement augmentation of screws for posterior instrumentation, are explored. MATERIALS AND METHODS: Eighteen human osteoporotic lumbar spines (L1-5) adjacent to vertebral bodies after vertebroplasty were tested in a servo-hydraulic machine. As augmentation compounds we used standard cement and a modified low-strength cement. Different anchoring pedicle screws were tested with and without cement augmentation in another cohort of human specimens with a simple pull-out test and a fatigue test that better reflects physiological conditions. RESULTS: Cement augmentation in the osteoporotic spine leads to greater biomechanical stability. However, change in vertebral stiffness resulted in alterations with the risk of adjacent fractures. By using a less firm cement compound, the risk of adjacent fractures is significantly reduced. Both screw augmentation techniques resulted in a significant increase in the withdrawal force compared with the group without cement. Augmentation using perforated screws showed the highest stability in the fatigue test. DISCUSSION AND CONCLUSION: The augmentation of cement leads to a significant change in the biomechanical properties. Differences in the stability of adjacent vertebral bodies increase the risk of adjacent fractures, which could be mitigated by a modified cement compound with reduced strength. Screws that were specifically designed for cement application displayed greatest stability in the fatigue test.

[Biomechanical aspects of vertebral augmentation]. / Biomechanische Aspekte der Augmentation im Bereich der Wirbelsäule.

BACKGROUND: With increasing age, bone mass decreases and the structure of the cancellous bone in the vertebral body changes. Especially in osteoporotic patients, but also with metastases in the vertebral body, this leads to decreased strength and, thus, to an increased risk of vertebral fractures. It is expected that this problem will increase significantly because of demographic developments. To treat or to prevent such vertebral fractures, different augmentation techniques have been developed. They can mainly be divided into vertebroplasty or kyphoplasty procedures. PURPOSE: The goal of this paper is to summarize biomechanical aspects of these augmentations procedures and to present some alternative methods. MATERIALS AND METHODS: With vertebroplasty, the loss of bone mass is balanced by injecting bone cement which improves the failure strength of the affected vertebral body. With kyphoplasty, cavities are created and these are filled with bone cement. RESULTS: Disadvantages of vertebroplasty are uncontrollable cement extrusion and increased fracture risk in the adjacent vertebral bodies. With balloon kyphoplasty, the adjacent cancellous bone is compacted during dilation and, thus, does not allow good integration with the remaining trabeculae. In addition, this method is associated with an increased risk of fracture in the adjacent vertebrae. To counter these disadvantages, a number of new types of cement and alternative augmentation methods are being developed, with which the vertebral body may be filled or distracted. CONCLUSION: The efficacy of these new methods should be tested in appropriate experimental biomechanical studies before they are used in patients.

[Treatment of osteoporotic vertebral compression fractures with PMMA-augmented pedicle screw fixation]. / Osteoporoticus kompressziós csigolyatörések kezelése PMMA-augmentált csavaros transpedicularis rögzítéssel.

BACKGROUND: Over the last few decades many innovative operation technique were developed due to the increase of porotic vertebral fractures. These new techniques aim to reach the required stability of the vertebral column. In case of significant instability, spinal canal stenosis or neural compression, decompressive intervention may be necessary, which results in further weakening of the column of the spine, the minimal invasive percutan vertebroplasty is not an adequate method to reach the required stability, that is why insertion of complementary pedicular screws is needed. Considering the limited screw-fixing ability of the porotic bone structure, with this new technique we are able to reach the appropriate stability of cement-augmented pedicle screws by dosing cement carefully through the screws into the vertebral body. We used this technique in our Institute in case of 12 patients and followed up the required stability and the severity of complications. METHODS: Fifteen vertebral compression fractures of 12 patients were treated in our Institute. Using the classification proposed by Genant et al. we found that the severity of the vertebral compression was grade 3 in case of 13, while grade 2 in case of two fractures. The average follow up time of the patients was 22 months (12-39), during this period X-ray, CT and clinical control examinations were taken. During the surgery the involved segments were localised by using X-ray and after the exploration the canulated screws were put through the pedicles of the spine and the vertebral body was filled through the transpedicular screws with bone cement. Depending on the grade of the spinal canal stenosis, we made the decompression, vertebroplasty or corpectomy of the fractured vertebral body, and the replacement of the body. Finally the concerned segments were fixed by titanium rods. RESULTS: In all cases the stenosis of spinal canal was resolved and the bone cement injected into the corpus resulted in adequated stability of the spine. In case of six patients we observed cement extravasation without any clinical signs, and by one patient--as a serious complication--pulmonary embolism. Neurological progression or screw loosening were not detected during the follow up period. Part of the patients had residual disability after the surgery due to their older ages and the problem of their rehabilitation process. CONCLUSION: After the right consideration of indications, age, general health condition and the chance of successful rehabilitation, the technique appears to be safe for the patients. With the use of this surgical method, the stability of the spine can be improved compared to the preoperative condition, the spinal canal stenosis can be solved and the neural structures can be decompressed. The severity of complications can be reduced by a precise surgical technique and the careful use of the injected cement. The indication of the surgical method needs to be considered in the light of the expected outcome and the rehabilitation.

Percutaneous vertebroplasty for painful spinal metastasis with epidural encroachment.

BACKGROUND AND OBJECTIVES: Spinal metastasis with epidural encroachment is regarded by several authors to be a contraindication to percutaneous vertebroplasty (PVP) because of the risk of increasing symptomatic leakage of cement. This analysis aims to evaluate the safety and efficacy of PVP in patients with painful spinal metastasis and encroachment of epidural space. METHODS: A retrospective study was conducted to review 43 consecutive patients with spinal metastasis that underwent PVP, for a total of 69 affected levels. All patients had at least 1 level associated with epidural encroachment related to metastasis. Among these patients, 14 had signs of spinal cord or cauda equina compression. Pain intensity was scored on a visual-analog scale (VAS). The analgesic efficacy was defined as at least 50% improvement in pain score as compared with the pre-procedure baseline and post-procedure. Clinical improvement of neurological compressive symptoms was defined as a decrease in ASIA impairment scale from baseline of 1 point or more. RESULTS: The analgesic efficacy was achieved in 89.7% of survival patients at 1 month, 87.5% at 3 months, 86.9% at 6 months, and 84.6% at 1 year. Small amount cement leakages were detected in 69.6% of treated levels without clinical complications. No deterioration of spinal cord or cauda equina compression symptoms was observed after a PVP in any patients. The different grade of epidural encroachment of the lesions was not correlated with filling volume or extraosseous leakage (P > 0.05). The treated levels with epidural encroachment showed a statistically significant relationship to spinal-canal leakage (P < 0.05). CONCLUSIONS: PVP can be performed safely and effectively in patients with painful spinal metastasis and epidural encroachment.

Percutaneous vertebroplasty performed with an 18-gauge needle for treatment of metastatic severe compression fracture of the cervical vertebral body.

Percutaneous vertebroplasty (PVP) is considered technically difficult in patients with severe vertebral body compression, especially in the cervical spine. In this study, PVP was successfully performed with the use of an 18-gauge angiographic needle in four patients with severe cervical compression fractures from metastatic disease. There were no complications, and relief of pain was immediate in all patients. This technique may be an alternative treatment for intractable pain secondary to severe cervical compression fractures.

Significantly reduced radiation dose to operators during percutaneous vertebroplasty using a new cement delivery device.

BACKGROUND: Percutaneous vertebroplasy (PVP) might lead to significant radiation exposure to patients, operators, and operating room personnel. Therefore, radiaton exposure is a concern. The aim of this study was to present a remote control cement delivery device and study whether it can reduce dose exposue to operators. METHODS: After meticulous preoperative preparation, a series of 40 osteoporosis patients were treated with unilateral approach PVP using the new cement delivery divice. We compared levels of fluoroscopic exposure to operator standing on different places during operation. group A: operator stood about 4 meters away from X-ray tube behind the lead sheet. group B: operator stood adjacent to patient as using conventional manual cement delivery device. RESULTS: During whole operation process, radiation dose to the operator (group A) was 0.10 ± 0.03 (0.07-0.15) µSv, group B was 12.09 ± 4.67 (10-20) µSv. a difference that was found to be statistically significant (P < 0.001) between group A and group B. CONCLUSION: New cement delivery device plus meticulous preoperative preparation can significantly decrease radiation dose to operators.

Biomechanical comparison of vertebral augmentation with silicone and PMMA cement and two filling grades.

PURPOSE: Vertebral augmentation with PMMA is a widely applied treatment of vertebral osteoporotic compression fractures. Subsequent fractures are a common complication, possibly due to the relatively high stiffness of PMMA in comparison with bone. Silicone as an augmentation material has biomechanical properties closer to those of bone and might, therefore, be an alternative. The study aimed to investigate the biomechanical differences, especially stiffness, of vertebral bodies with two augmentation materials and two filling grades. METHODS: Forty intact human osteoporotic vertebrae (T10-L5) were studied. Wedge fractures were produced in a standardized manner. For treatment, PMMA and silicone at two filling grades (16 and 35 % vertebral body fill) were assigned to four groups. Each specimen received 5,000 load cycles with a high load range of 20-65 % of fracture force, and stiffness was measured. Additional low-load stiffness measurements (100-500 N) were performed for intact and augmented vertebrae and after cyclic loading. RESULTS: Low-load stiffness testing after cyclic loading normalized to intact vertebrae showed increased stiffness with 35 and 16 % PMMA (115 and 110 %) and reduced stiffness with 35 and 16 % silicone (87 and 82 %). After cyclic loading (high load range), the stiffness normalized to the untreated vertebrae was 361 and 304 % with 35 and 16 % PMMA, and 243 and 222 % with 35 and 16 % silicone augmentation. For both high and low load ranges, the augmentation material had a significant effect on the stiffness of the augmented vertebra, while the filling grade did not significantly affect stiffness. CONCLUSIONS: This study for the first time directly compared the stiffness of silicone-augmented and PMMA-augmented vertebral bodies. Silicone may be a viable option in the treatment of osteoporotic fractures and it has the biomechanical potential to reduce the risk of secondary fractures.

Bone augmentation for cancellous bone- development of a new animal model.

BACKGROUND: Reproducible and suitable animal models are required for in vivo experiments to investigate new biodegradable and osteoinductive biomaterials for augmentation of bones at risk for osteoporotic fractures. Sheep have especially been used as a model for the human spine due to their size and similar bone metabolism. However, although sheep and human vertebral bodies have similar biomechanical characteristics, the shape of the vertebral bodies, the size of the transverse processes, and the different orientation of the facet joints of sheep are quite different from those of humans making the surgical approach complicated and unpredictable. Therefore, an adequate and safe animal model for bone augmentation was developed using a standardized femoral and tibia augmentation site in sheep. METHODS: The cancellous bone of the distal femur and proximal tibia were chosen as injection sites with the surgical approach via the medial aspects of the femoral condyle and proximal tibia metaphysis (n = 4 injection sites). For reproducible drilling and injection in a given direction and length, a custom-made c-shaped aiming device was designed. Exact positioning of the aiming device and needle positioning within the intertrabecular space of the intact bone could be validated in a predictable and standardized fashion using fluoroscopy. After sacrifice, bone cylinders (Ø 32 mm) were harvested throughout the tibia and femur by means of a diamond-coated core drill, which was especially developed to harvest the injected bone area exactly. Thereafter, the extracted bone cylinders were processed as non-decalcified specimens for µCT analysis, histomorphometry, histology, and fluorescence evaluation. RESULTS: The aiming device could be easily placed in 63 sheep and assured a reproducible, standardized injection area. In four sheep, cardiovascular complications occurred during surgery and pulmonary embolism was detected by computed tomography post surgery in all of these animals. The harvesting and evaluative methods assured a standardized analysis of all samples. CONCLUSIONS: This experimental animal model provides an excellent basis for testing new biomaterials for their suitability as bone augmentation materials. Concomitantly, similar cardiovascular changes occur during vertebroplasties as in humans, thus making it a suitable animal model for studies related to vertebroplasty.

Hypothermic manipulation of bone cement can extend the handling time during vertebroplasty.

BACKGROUND: Polymethylmethacrylate (PMMA) is commonly used for clinical applications. However, the short handling time increases the probability of a surgeon missing the crucial period in which the cement maintains its ideal viscosity for a successful injection. The aim of this article was to illustrate the effects a reduction in temperature would have on the cement handling time during percutaneous vertebroplasty. METHODS: The injectability of bone cement was assessed using a cement compressor. By twisting the compressor, the piston transmits its axial load to the plunger, which then pumps the bone cement out. The experiments were categorized based on the different types of hypothermic manipulation that were used. In group I (room temperature, sham group), the syringes were kept at 22°C after mixing the bone cement. In group 2 (precooling the bone cement and the container), the PMMA powder and liquid, as well as the beaker, spatula, and syringe, were stored in the refrigerator (4°C) overnight before mixing. In group 3 (ice bath cooling), the syringes were immediately submerged in ice water after mixing the bone cement at room temperature. RESULTS: The average liquid time, paste time, and handling time were 5.1 ± 0.7, 3.4 ± 0.3, and 8.5 ± 0.8 min, respectively, for group 1; 9.4 ± 1.1, 5.8 ± 0.5, and 15.2 ± 1.2 min, respectively, for group 2; and 83.8 ± 5.2, 28.8 ± 6.9, and 112.5 ± 11.3 min, respectively, for group 3. The liquid and paste times could be increased through different cooling methods. In addition, the liquid time (i.e. waiting time) for ice bath cooling was longer than for that of the precooling method (p < 0.05). CONCLUSIONS: Both precooling (i.e. lowering the initial temperature) and ice bath cooling (i.e. lowering the surrounding temperature) can effectively slow polymerization. Precooling is easy for clinical applications, while ice bath cooling might be more suitable for multiple-level vertebroplasty. Clinicians can take advantage of the improved injectability without any increased cost.

Augmentation of transpedicular screws by intraoperative vertebroplasty.

BACKGROUND AND PURPOSE: The aim of the study was to determine the efficacy of posterior spinal stabilization, combined with intraoperative vertebroplasty defined as intraoperative filling of instrumented vertebral bodies (VB) with polymethylmethacrylate (PMMA). MATERIAL AND METHODS: Seventeen patients with osteoporosis or osteopenia underwent posterior spinal fusions. The surgical procedures included laminectomy, spondylodesis, insertion of pedicular screws, intraoperative vertebroplasty and correction of spinal deformity. RESULTS: Postoperative assessment showed improvement of pain in all cases. Motor deficit regressed in 2 of 3 afflicted patients. In 12 vertebrae (27.3%), the mass of PMMA ex-tended from one endplate to another, filling 100% of VB height, in 7 (15.9%) it filled 90-99%, in 14 (31.8%) 80-89%, in 9 (20.4%) 70-79%, and in 2 (4.5%) it filled 50-60% of VB height. In the horizontal plane, PMMA filled central parts of 72.7% of vertebral bodies. PMMA completely surrounded 68.9% of screws, and partially surrounded 18.4% of screws, whereas 12.6% of screws had no contact with cement mass. Spinal stabilization reduced kyphotic deformity in 15 patients (range of reduction: 6°-25°; mean: 13.6°). During follow-up (3-32 months; mean: 16) implants of 11 patients were stable, 1 implant instability was diagnosed 7 months after surgery, 5 patients were lost to follow-up. Asymptomatic cement leaks occurred in 45% of vertebrae. CONCLUSIONS: Intraoperative vertebroplasty performed after insertion of pedicular screws may be considered as a technical variation useful to stabilize osteoporotic spines. After PMMA hardening, intraoperative manoeuvres to correct spinal deformity were possible without any damage of instrumented vertebrae.

Comparison of polymethylmethacrylate versus expandable cage in anterior vertebral column reconstruction after posterior extracavitary corpectomy in lumbar and thoraco-lumbar metastatic spine tumors.

Single-stage posterior corpectomy for the management of spinal tumors has been well described. Anterior column reconstruction has been accomplished using polymethylmethacrylate (PMMA) or expandable cages (EC). The aim of this retrospective study was to compare PMMA versus ECs in anterior vertebral column reconstruction after posterior corpectomy for tumors in the lumbar and thoracolumbar spine. Between 2006 and 2009 we identified 32 patients that underwent a single-stage posterior extracavitary tumor resection and anterior reconstruction, 16 with PMMA and 16 with EC. There were no baseline differences in regards to age (mean: 58.2 years) or performance status. Differences between groups in terms of survival, estimated blood loss (EBL), kyphosis reduction (decrease in Cobb's angle), pain, functional outcomes, and performance status were evaluated. Mean overall survival and EBL were 17 months and 1165 ml, respectively. No differences were noted between the study groups in regards to survival (p = 0.5) or EBL (p = 0.8). There was a trend for better Kyphosis reduction in favor of the EC group (10.04 vs. 5.45, p = 0.16). No difference in performance status or VAS improvements was observed (p > 0.05). Seven patients had complications that led to reoperation (5 infections). PMMA or ECs are viable options for reconstruction of the anterior vertebral column following tumor resection and corpectomy. Both approaches allow for correction of the kyphotic deformity, and stabilization of the anterior vertebral column with similar functional and performance status outcomes in the lumbar and thoracolumbar area.

Percutaneous vertebral augmentation: StabilitiT a new delivery system for vertebral fractures.

Percutaneous vertebral augmentation for compression fractures with bone cement has become an increasingly popular form of treatment. Various delivery techniques and bone cements have been developed. StabiliT Vertebral Augmentation System (DFINE Inc., San Jose, CA) is a unique radiofrequency (RF) based system which delivers an ultra-high viscosity bone cement. The patented StabiliT ER bone cement has an extended working time prior to RF warming. When delivered through this unique hydraulic system an on-demand ultra-high viscosity cement can be delivered into an osteotome created cavity resulting in a clinical procedure with the best qualities of both vertebroplasty and conventional balloon assisted kyphoplasty.

[Experimental study of percutaneous vertebroplasty with a novel bone void filling container system].

OBJECTIVE: To investigate vertebral augmentation with a novel reticulate bone filling container system by polymethyl methacrylate (PMMA) injection in cadaveric simulated vertebral compressive fracture and explore the effect of reticulate bone filling container on cement distribution controlling within vertebral body and the restoration of biomechanical properties after augmentation. METHODS: A total of 28 freshly frozen human vertebrae specimens were randomly divided into 4 groups. After the measurements of bone mineral density (BMD) and vertebral height, each vertebra received an axle load by a MTS (material testing system) machine to test the initial strength and stiffness. Subsequently a simultaneous compressive fracture model was created to measure the stiffness and height of fractured vertebrae. Then the augmentation procedure was performed. Afterward the biomechanical properties and the vertebral height were similarly measured as pre-operatively. The expansion of bone filling container and the distribution of cement within vertebral body were morphologically observed by crossing the specimens in sagittal midline and also integrated with the radiographic results. RESULTS: Stiffness was significantly restored comparing with that of fractured level (P < 0.05). And the bipedicular groups had better restoration results than the unipedicular groups. The strength and height of specimens significantly increased after the augmentation procedure but without difference among groups. In axial radiographic view, the distribution of cement in vertebral body was oval or long oval-shaped in double-layer bone filling container groups while it was irregular in single-layer groups. After crossing, the double-layer version expanded well in vertebral body and could enwrap most of injected cement. There was only a little leakage near the vessel layer. But the single-layer version had a poor expansion and a large amount of cement leakage. CONCLUSION: This novel reticulate bone void filling container system with different layers may restore both the biomechanical properties and the height of fractured vertebrae. But, with the benefit of reducing cement leakage, a double-layer design can enwrap most of injected PMMA and has a brighter prospect of clinical application.