Injection Of Polymethylmethacrylate Research Articles

Experimental ex-vivo validation of PMMA-based bone cements loaded with magnetic nanoparticles enabling hyperthermia of metastatic bone tumors

Percutaneous vertebroplasty comprises the injection of Polymethylmethacrylate (PMMA) bone cement into vertebrae and can be used for the treatment of compression fractures of vertebrae. Metastatic bone tumors can cause such compression fractures but are not treated when injecting PMMA-based bone cement. Hyperthermia of tumors can on the other hand be attained by placing magnetic nanoparticles (MNPs) in an alternating magnetic field (AMF). Loading the PMMA-based bone cement with MNPs could both serve vertebra stabilization and metastatic bone tumor hyperthermia when subjecting this PMMA-MNP to an AMF. A dedicated pancake coil is designed with a self-inductance of 10 μH in series with a capacitance of 0.1 μF that acts as resonant inductor-capacitor circuit to generate the AMF. The thermal rise is appraised in beef vertebra placed at 10 cm from the AMF generating circuit using optical temperatures sensors, i.e. in the center of the PMMA-MNP bone cement, which is located in the vicinity of metastatic bone tumors in clinical applications; and in the spine, which needs to be safeguarded to high temperature exposures. Results show a temperature rise of about 7 °C in PMMA-MNP whereas the temperature rise in the spine remains limited to 1 °C. Moreover, multicycles heating of PMMA-MNP is experimentally verified, validating the technical feasibility of having PMMA-MNP as basic component for percutaneous vertebroplasty combined with hyperthermia treatment of metastatic bone tumors.

Computed Tomography-Guided SCREW Fixation PLUS Cementoplasty in Myeloma Patients

INTRODUCTION:The aim of this report is to evaluate feasibility, safety and activity of a new procedure of computed tomography (CT) - guided percutaneous screw fixation (PSF) plus cementoplasty for treatment of mielomatous osteolytic lesions with refractory pain and fracture or to prevent impending pathological fractures. The association of scew fixation with cementoplasty allows, compared to cementoplasty alone, a better augmentation of the bone and reduces the risk of cement leakage through a selective injection of the of polymethylmethacrylate (especially in case of lytic lesion of vertebral pedicle). METHODSFrom September 2014 to May 2016 thirteen (13) consecutive patients (eight men and five women, median age 67 years, range 48-78 years) with Multiple Myeloma who had developed painful and symptomatic bone lytic lesions in the pelvis and vertebrae were submitted to the procedure (three patients underwent multiple interventions). This consisted of PSF followed by percutaneous bone-cement injection with an solution of polymethylmethacrylate (PMMA) in eighteen sessions. The procedures were performed into the thoracic vertebrae (three interventions), lumbar vertebrae (nine interventions), pelvis (five interventions, bilateral in one instance) and into a paravertebral mass which involved the fifth and sixth thoracic vertebrae. For the osteosynthesis we used cannulated screws with lateral holes, that allow to selectively inject the cement through the screw avoiding undesired leakage. After the screw insertion, to obtain a better augmentation of the bone, from 8 to 22 ml of PMMA in all the lesions. In two cases, before the PSF and PMMA injection, in order to reduce the volume of the tumor a radiofrequency ablation was performed. All the procedures were performed using local anesthesia, conscious sedation in all patients and antibiotic prophylaxis with ceftriaxone 2 gr i.v. Pain was measured by visual analogue scale (range 0-10), mobility by functional mobility score system with a range from 1 (normal mobility) to 4 (bedridden). Statistical analysis was performed using the test of Wilcoxon. RESULTSTechnical success was achivied in all patients. The CT scan acquired immediately after the procedure didn’t demonstrate any complications such as leakage of cement or incorrect positioning of the screws or undesired burning during thermal ablation. No additional bone fractures occurred during a median follow-up of 19 months (range 3-23 months). Pain relief occurred in all the patients within one month. Median VAS score was 7 (range 4-9), 3 (range1-4) and 1 (range 1-2) before, at one and six months after procedure respectively (p<0.05). Median functional mobility score was 3 (range 2-4), 2 (range 2-3) and 1 (range 1-2) before, at one and six months after the procedure respectively (p<0.05). All patients required analgesic therapy with opiods and no-steroidal anti-inflammatory agents/analgesics (NSAIAs).Only three patients needed opioid therapy after the procedure. CONCLUSIONThe PSF plus cemetoplasty of the pelvis and vertebrae is safe and effective in patients affected by myelomatous localizzations. The procedure is minimally invasive and allows to stabilize the fracture and prevent pathological fractures with significant pain relief and good recovery of walking ability. Further controlled studies with large series of patients are warranted to confirm these preliminary results. DisclosuresNo relevant conflicts of interest to declare.

A Review of PMMA Bone Cement and Intra-Cardiac Embolism.

Percutaneous vertebroplasty procedure is of major importance, given the significantly increasing aging population and the higher number of orthopedic procedures related to vertebral compression fractures. Vertebroplasty is a complex technique involving the injection of polymethylmethacrylate (PMMA) into the compressed vertebral body for mechanical stabilization of the fracture. Our understanding and ability to modify these mechanisms through alterations in cement material is rapidly evolving. However, the rate of cardiac complications secondary to PMMA injection and subsequent cement leakage has increased with time. The following review considers the main effects of PMMA bone cement on the heart, and the extent of influence of the materials on cardiac embolism. Clinically, cement leakage results in life-threatening cardiac injury. The convolution of this outcome through an appropriate balance of complex material properties is highlighted via clinical case reports.

Evaluation of an injectable hydrogel and polymethyl methacrylate in restoring mechanics to compressively fractured spine motion segments

Background ContextCompressive fracture can produce profound changes to the mechanical profile of a spine segment. Minimally invasive repair has the potential to restore both function and structural integrity to an injured spine. Use of both hydrogels to address changes to the disc, combined with polymethyl methacrylate (PMMA) to address changes to the vertebral body, has the potential to facilitate repair. PurposeThe purpose of this investigation was to determine if the combined use of hydrogel injection and PMMA could restore the mechanical profile of an axially injured spinal motion segment. Study DesignThis is a basic science study evaluating a combination of hydrogel injection and vertebroplasty on restoring mechanics to compressively injured porcine spine motion segments. MethodsFourteen porcine spine motion segments were subject to axial compression until fracture using a dynamic servohydraulic testing apparatus. Rotational and compressive stiffness was measured for each specimen under the following conditions: initial undamaged, fractured, fatigue loading under compression, hydrogel injection, PMMA injection, and fatigue loading under compression. Group 1 received hydrogel injection followed by PMMA injection, whereas Group 2 received PMMA injection followed by hydrogel injection. This study was funded under a Natural Sciences and Engineering Research Council of Canada discovery grant. ResultsPMMA injection was found to alter the compressive stiffness properties of axially injured spine motion segments, restoring values from Groups 1 and 2 to 89.3%±29.3% and 81%±27.9% of initial values respectively. Hydrogel injection was found to alter the rotational stiffness properties, restoring specimens in Groups 1 and 2 to 151.5%±81% and 177.2%±54.9% of initial values respectively. Prolonged restoration of function was not possible, however, after further fatigue loading. ConclusionsUsing this repair technique, replication of the mechanism of injury appears to cause a rapid deterioration in function of the motion segments. Containment of the hydrogel appears to be an issue with large breaches in the end plate, as it is posited to migrate into the cancellous bone of the vertebral body. Future work should attempt to evaluate methods in fully sealing the disc space.

The role of intraoperative scrape cytology in vertebroplasty.

Aims:To assess the adequacy of intraoperative scrape cytology during percutaneous vertebroplasty by correlating results with corresponding histopathology.Settings and Design:Vertebroplasty is a procedure increasingly used to treat painful vertebral compression fractures. The history and presentation of osteoporotic fractures are straightforward, but difficulty arises in differentiating infective from neoplastic lesions, especially in cases where the magnetic resonance imaging is equivocal. The procedure involves injection of polymethyl methacrylate (bone cement) into the pathological vertebral body and gives dramatic pain relief. It is indicated in osteoporotic and neoplastic lesions but contraindicated in infections. Hence, intraoperative evaluation of a specimen is essential to aid in the decision of performing vertebroplasty.Subjects and Methods:A total of 128 patients with vertebral lesions underwent core biopsy and scrape cytology from June 2006 to June 2015. Based on the findings of cytological examination, malignant lesions were subjected to vertebroplasty. In lesions with infective etiology, vertebroplasty was abandoned and antibiotic or antituberculous therapy started.Results:The overall diagnostic accuracy of scrape cytology was excellent with 97.58% cases correlating with the final histopathological diagnosis. Specificity was 100%, positive predictive value was 100% and negative predictive value was 33.33%.Conclusion:Scrape cytology is a simple, rapid, accurate cytodiagnostic technique and should be routinely utilized in vertebral lesions for intraoperative consultation and decision making during vertebroplasty.

Targeted Therapy for Low Back Pain in Elderly Degenerative Lumbar Scoliosis: A Cohort Study.

Prospective cohort study. To compare the novel treatment procedure with nonoperative treatment for low back pain (LBP) in elderly patients with degenerative lumbar scoliosis (DLS). Treatment of LBP associated with elderly DLS is controversial. We developed a novel treatment procedure, termed percutaneous intervertebral-vacuum polymethylmethacrylate injection (PIPI). We included patients with de novo DLS aged ≥65 years who had LBP with a visual analogue scale (VAS) score of >50 for ≥6 months with intervertebral vacuum and vertebral bone marrow edema (BME) defined on fat-saturated T2-weighted or gadolinium-enhanced T1-weighted magnetic resonance imaging. The primary outcomes were evaluated using the VAS score and modified Oswestry Disability Index (ODI). As an objective measurement, we scored BME on magnetic resonance imaging. Between August 2004 and July 2011, 109 patients underwent PIPI and 53 received nonoperative treatment. At 1 month, mean improvements in VAS scores were -55.3 (95% CI, -60.5 to -50.1) and -1.9 (CI, -7.7 to 3.8) and mean improvements in ODI were -22.7 (CI, -27.3 to -18.2) and -0.6 (CI, -6.6 to 5.4) for the PIPI and nonoperative groups, respectively. At 2 years, mean improvements in VAS scores were -52.2 (CI, -59.9 to -44.4) and -4.0 (CI, -10.9 to 3.0) and mean improvements in ODI were -20.7 (CI, -27.3 to -14.5) and -1.0 (CI, -7.7 to 5.7) for the PIPI and nonoperative groups, respectively. BME substantially decreased in the PIPI group compared with the nonoperative group (P <0.001) and correlated with VAS score and ODI improvements (VAS score: r = 0.502, P <0.001; ODI: r = 0.372, P <0.001). PIPI improved treatment for LBP, with a sustained clinical benefit for at least 2 years. 3.

Balloon Kyphoplasty Is a Safe and Effective Option for the Treatment of Vertebral Compression Fractures in Solid-Organ Transplant Recipients

Solid-organ transplant recipients are at great risk for osteoporotic vertebral compression fractures because of both underlying pretransplant bone diseases and posttransplant immunosuppressive treatments. Balloon kyphoplasty is a minimally invasive procedure that is used to treat painful osteoporotic vertebral compression fractures. It involves injection of polymethylmethacrylate into the vertebral body to stabilize the fracture and to alleviate the pain immediately. In this study, we report the results of balloon kyphoplasty for treatment of vertebral compression fractures in solid-organ transplant recipients. We retrospectively reviewed 512 liver transplant and 2248 kidney transplant procedures that were performed in our center between 1985 and 2015. Seven transplant recipients with a total of 10 acute, symptomatic vertebral compression fractures who were unresponsive to conservative treatment for 3 weeks underwent balloon kyphoplasty. Clinical outcome was graded using the visual analog scale. Radiographic evaluation included measurement of the segmental kyphosis by the Cobb method. There were 4 female and 3 male patients in our study group. Ages of patients ranged from 56 to 63 years with an average age of 58.8 years. The affected vertebral levels varied from T12 to L4. Mean follow-up after balloon kyphoplasty was 3.4 years, and mean time interval from transplant to balloon kyphoplasty was 8.6 years. Statistically significant difference is evident 3 years after transplant surgery (P < .05). Sagittal alignment improved (> 5 degrees) in 2 of 7 patients (28%). Transplant recipients are at great risk in terms of vertebral compression fracture development, especially within 1 year after transplant. Although conservative treatment has been the first treatment choice for vertebral compression fracture, long treatment time and high costs may be needed to achieve cure. Experience with our small patient population showed that balloon kyphoplasty was effective and safe for obtaining rapid pain relief and earlier mobilization with fewer complications.

Evaluation of the biphasic calcium composite (BCC), a novel bone cement, in a minipig model of pulmonary embolism

Polymethylmethacrylate (PMMA) bone cement, which is used as a filler material in vertebroplasty, is one of the major sources of pulmonary embolism in patients who have undergone vertebroplasty. In the present study, we established and evaluated two animal models of pulmonary embolism by injecting PMMA or biphasic calcium composite (BCC) bone cement with a negative surface charge. A total of 12 adults and healthy Wuzhishan minipigs were randomly divided into two groups, the PMMA and BBC groups, which received injection of PMMA bone cement and BBC bone cement with a negative surface charge in the circulation system through the pulmonary trunk, respectively, to construct animal models of pulmonary embolism. The hemodynamics, arterial blood gas, and plasma coagulation were compared between these two groups. In addition, morphological changes of the lung were examined using three-dimensional computed tomography. The results showed that both PMMA and BCC injections induced pulmonary embolisms in minipigs. Compared to the PMMA group, the BCC group exhibited significantly lower levels of arterial pressure, pulmonary artery pressure, blood oxygen pressure, blood carbon dioxide pressure, blood bicarbonate, base excess, antithrombin III and D-dimer. In conclusion, BCC bone cement with a negative surface charge is a promising filler material for vertebroplasty.

Complications and Management of Polymethylmethacrylate (PMMA) Injections to the Midface.

Polymethylmethacrylate (PMMA) has been used as an injectable filler to treat hollows and reduce rhytids. PMMA injections have been associated with several side effects, however, the literature is scarce on periorbital complications and their treatments. The purpose of this study is to report a series of complications after periorbital PMMA injections to the midface and to describe their management. Retrospective chart review, including photography and histopathology when available. The authors identified 11 cases of complications of PMMA injections to the midface. Patient ages ranged from 36 to 62 years (mean, 47 years; median, 44 years). Two (18%) were males and 9 (82%) were females. Adverse effects began between 2 to 24 months after injection (mean, 7.2 months; median, 6 months). All patients had edema, erythema, and contour irregularity. Seven (64%) patients had nodules, 4 (36%) had yellow, xanthomatous skin changes, and 2 (18%) had eyelid malposition. Histopathology demonstrated a giant cell inflammation in 5 of 6 cases. Corticosteroid injection was tried in 6 cases but was associated with minimal clinical improvement. Surgical debulking of the implanted material was performed in 9 (82%) cases and was effective in improving edema, erythema, and nodularity. PMMA injection to the midface may be associated with chronic inflammation, fibrotic nodules, yellowing of the skin, and eyelid malposition. Intralesional corticosteroid injections yielded minimal or no improvement; surgical debulking achieved favorable results. LEVEL OF EVIDENCE 4: Therapeutic.

Location of injected polymethylmethacrylate microspheres influences the onset of late adverse effects: an experimental and histopathologic study.

Polymethylmethacrylate (PMMA) has been widely used in the correction of wrinkles because of its long-lasting cosmetic improvements. However, side effects and complications may occur, and its clinical appearance on the oral mucosa can be similar to that of inflammatory or neoplastic disease. The aim of this research was to compare the clinical and histopathologic responses to PMMA injected by two different methods. Twenty-two rats received an injection of PMMA using the tunneling technique (gold standard), with subcutaneous deposition of the filler in the face, or a variation of the technique with transcutaneous submucosal deposition of the filler in the cheek. The tissue reaction was analyzed clinically every 24 hours during the first week, then once a week for the following 3 months. Histologic evaluation was based on the local inflammatory response to the filler. No clinical changes were observed during the initial evaluation period (0–14 days). After 14 days, only the submucosal group showed extra-oral enlargement (n=4, 18.2%). Histopathologic analysis revealed nodule formation in four animals (18.2%) in the submucosal group, with no nodules observed in the subcutaneous group. The data obtained in this study demonstrate that the technique used to deliver the filler may influence the risk of adverse reactions.

Combined Microwave Ablation and Cementoplasty in Patients with Painful Bone Metastases at High Risk of Fracture.

To retrospectively evaluate the effectiveness of computed tomography-guided percutaneous microwave ablation (MWA) and cementoplasty in patients with painful bone metastases at high risk of fracture. Thirty-five patients with 37 metastatic bone lesions underwent computed tomography-guided MWA combined with cementoplasty (polymethylmethacrylate injection). Vertebrae, femur, and acetabulum were the intervention sites and the primary end point was pain relief. Pain severity was estimated by visual analog scale (VAS) before treatment; 1 week post-treatment; and 1, 6, and 12 months post-treatment. Functional outcome was assessed by improved patient walking ability. Radiological evaluation was performed at baseline and 3 and 12 months post-procedure. In all patients, pain reduction occurred from the first week after treatment. The mean reduction in the VAS score was 84, 90, 90 % at week 1, month 1, and month 6, respectively. Improved walking ability occurred in 100 and 98 % of cases at the 1- and 6-month functional outcome evaluations, respectively. At the 1-year evaluation, 25 patients were alive, and 10 patients (28 %) had died because of widespread disease. The mean reduction in the VAS score and improvement in surviving patients' walking ability were 90 and 100 %, respectively. No patients showed evidence of local tumor recurrence or progression and pathological fracture in the treated sites. Our results suggest that MWA combined with osteoplasty is safe and effective when treating painful bone metastases at high risk of fracture. The number of surviving patients at the 1-year evaluation confirms the need for an effective and long-lasting treatment.

The correlation analysis of balloon volume and bone cement volume in percutaneous kyphoplasty

To analyze the percutaneous kyphoplasty (PKP) data statistically to predict the bone cement volume (CV). Retrospective analysis of 93 patients with 154 vertebrae of osteoporotic vertebra compressed fracture, who received PKP from January 2012 to December 2013 in Beijing Tian Tan Hospital, Capital Medical University. All procedures were bilateral and non-high-pressure polymethyl methacrylate injection. The balloon volume (BV), balloon peak pressure (Pmax), CV and the ratio of Pmax to BV (P/BV) were documented. The data was analyzed by correlation analysis and linear regression analysis to reveal the correlation between BV and CV. Seven vertebrae had bone cement leakage, no intraspinal leakage, no neuro-deficit. Visual analogue scale was 0-2 of all patients on 3 d postoperation. The data of 147 vertebrae without leakage: BV was 2.1-6.3 ml, Pmax was 130-359 psi, CV was 2.8-8.5 ml, and the ratio of Pmax to BV (P/BV) was 25-263 psi/ml. The data analysis showed there was no high correlation between BV and CV as one group (R<0.75). However if divided the data into three groups by the value of P/BV, group A (P/BV<100), group B (100≤P/BV<200), group C (P/BV≥200), there was high correlation and linear relationship between BV and CV in each group (R>0.75, P<0.01). CV was 0.9-1.1 times of BV in group A; CV was 1.4-1.6 times of BV in group B; and CV was 2.0-2.2 times of BV in group C. CV is predictable by the BV and the ratio of Pmax to BV. It can reduce the rate of the leakage, and also can prevent the unsatisfactory results by insufficient bone cement volume.

Unilateral or bilateral percutaneous vertebroplasty for acute osteoporotic vertebral fracture: a prospective study.

Percutaneous vertebroplasty (PVP) has been demonstrated to be effective in the treatment of acute osteoporotic vertebral fracture (AOVF). However, the matter of which surgical approach should be selected remains controversial. This research aims to compare the clinical results of unilateral and bilateral PVP for AOVF. From January 2008 to December 2011, 68 patients with AOVF were randomly assigned to the unilateral puncture group (n=36) or the bilateral group (n=32). These patients underwent percutaneous injection of polymethyl methacrylate into posterior pedicle by the unilateral or bilateral puncture approach. Visual analogue scale (VAS) and the Quality of Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO) were recorded on presentation, at 1 week, 3, 6, and 12 months after operation. The cement leakage was measured by x-ray and computed tomography scan. Follow-up data showed there were no significant differences in VAS and QUALEFFO between 2 groups at 1 week after PVP and only significant difference was observed between 2 groups at 3, 6, and 12 months after operation. The cement leakage was 52.7% in the unilateral puncture group and 28.1% in the bilateral group. Compared with unilateral puncture, use of bilateral approach during PVP may result in more superior long-term outcomes and less cement leakage for patients with AOVF.

Does metaphyseal cement augmentation in fracture management influence the adjacent subchondral bone and joint cartilage?: an in vivo study in sheep stifle joints.

Augmentation of implants with polymethylmethacrylate (PMMA) bone cement in osteoporotic fractures is a promising approach to increase implant purchase. Side effects of PMMA for the metaphyseal bone, particularly for the adjacent subchondral bone plate and joint cartilage, have not yet been studied. The following experimental study investigates whether subchondral PMMA injection compromises the homeostasis of the subchondral bone and/or the joint cartilage.Ten mature sheep were used to simulate subchondral PMMA injection. Follow-ups of 2 (4 animals) and 4 (6 animals) months were chosen to investigate possible cartilage damage and subchondral plate alterations in the knee. Evaluation was completed by means of high-resolution peripheral quantitative computed tomography (HRpQCT) imaging, histopathological osteoarthritis scoring, and determination of glycosaminoglycan content in the joint cartilage. Results were compared with the untreated contralateral knee and statistically analyzed using nonparametric tests.Evaluation of the histological osteoarthritis score revealed no obvious cartilage damage for the treated knee; median histological score after 2 months 0 (range 4), after 4 months 1 (range 5). There was no significant difference when compared with the untreated control site after 2 and 4 months (P = 0.23 and 0.76, respectively). HRpQCT imaging showed no damage to the metaphyseal trabeculae. Glycosaminoglycan measurements of the treated joint cartilage after 4 months revealed no significant difference compared with the untreated cartilage (P = 0.24).The findings of this study support initial clinical observation that PMMA implant augmentation of metaphyseal fractures appears to be a safe procedure for fixation without harming the subchondral bone plate and adjacent joint cartilage.

Vertebral augmentation for neoplastic lesions with posterior wall erosion and epidural mass.

The presence of a cortical erosion of the posterior wall or an epidural mass is commonly considered a contraindication to performing a vertebral augmentation, considering the perceived increased risk of an epidural cement leak. Our aim was to assess technical and clinical complications of vertebral augmentation procedures performed for pain palliation and/or stabilization of neoplastic lytic vertebral body lesions, with cortical erosion of the posterior wall, often associated with a soft-tissue epidural mass. In 48 patients, we performed retrospective vertebral augmentation assessment on 70 consecutive levels with cortical erosion of the posterior wall, as demonstrated by preprocedural CT/MR imaging. An epidural mass was present in 31/70 (44.3%) levels. Cavity creation was performed with Coblation Wands before cement injection in 59/70 levels. Injection of high-viscosity polymethylmethacrylate was performed under real-time continuous fluoroscopic control. Postprocedural CT of the treated levels was performed in all cases. Clinical follow-up was performed at 1 and 4 weeks postprocedurally. In 65/70 (92.8%) levels, the vertebral augmentation resulted in satisfactory polymethylmethacrylate filling of the lytic cavity and adjacent trabecular spaces in the anterior half of the vertebral body. An epidural leak of polymethylmethacrylate occurred in 10/70 (14.2%) levels, causing radicular pain in 3 patients, which spontaneously resolved within 1 week in 2 patients, while 1 patient with a T1-T2 foraminal leak developed severe weakness of the intrinsic hand muscles and a permanent motor deficit. In our series of vertebral augmentation of neoplastic lytic vertebral lesions performed for palliation of pain and/or stabilization, we observed a polymethylmethacrylate epidural leak in only 14.2% of levels, despite the presence of cortical erosion of the posterior wall and an epidural mass, with an extremely low rate of clinical complications. Our data seem to justify use of vertebral augmentation in patients with intractable pain or those at risk for vertebral collapse.

Fine Needle Aspiration Cytology in The Diagnosis of a Perioral Adverse Reaction to Permanent Cosmetic Dermal Filler: Case Report

Facial cosmetic procedures are increasingly requested, and dermal filler materials are widely used as a nonsurgical option of treatment. However, injectable fillers have been implicated in a series of local adverse reactions. Woman, 69, reported a painful nodule on her right nasolabial fold. Fine needle aspiration cytology (FNAC) was used to obtain a diagnosis. The test revealed the problem as a granulomatous foreign-body reaction caused by the perioral injection of polymethylmethacrylate (PMMA) dermal filler. FNAC could be a useful and minimally invasive method to confirm the diagnosis of adverse reactions caused by perioral cosmetic dermal fillers such as PMMA.

Biomechanical evaluation of the primary stability of pedicle screws after augmentation with an innovative bone stabilizing system

In today's aging population, diminished bone quality often affects the outcome of surgical treatment. This occurs especially when surgical implants must be fixed to bone, as it occurs when lumbar fusion is performed with pedicle screws. Besides Polymethylmethacrylate (PMMA) injection, several techniques have been developed to augment pedicle screws. The aim of the current study was to evaluate the primary stability of an innovative system (IlluminOss™) for the augmentation of pedicle screws in an experimental cadaveric setup. IlluminOss™ is an innovative technology featuring cement with similar biochemical characteristics to aluminum-free glass-polyalkenoate cement (GPC). IlluminOss™ was inserted transpedicularly via a balloon/catheter system in 40 human cadaveric lumbar vertebrae. For comparability, each vertebra was treated bilaterally with pedicle screws, augmented and non-augmented. The maximum failure load during pull out test was documented by a universal material testing machine. The results showed significantly higher failure loads for the augmented pedicle screws (Median 555.0 ± 261.0 N, Min. 220.0 N, Max. 1,500.0 N), compared to the native screws (Median 325.0 ± 312.1 N, Min. 29.0 N, Max. 1,400.0 N). Based on these data, we conclude the IlluminOss™ system can be used to augment primary screw stability regarding axial traction, compared to native screws. The IlluminOss™ monomer offers ease of control for use in biological tissues. In contrast to PMMA, no relevant heat is generated during the hardening process and there is no risk of embolism. Further studies are necessary to evaluate the usefulness of the IlluminOss™ system in the in vivo augmentation of pedicle screws in the future.

Percutaneous Kyphoplasty versus Conservative Treatment in Acute and Subacute Osteoporotic Vertebral Compression Fractures (OVCF): A Double-Blinded, Randomized Controlled Clinical Trial (RCT) in the Population of Western China

Vertebral compression fracture (VCF) is one of the most common causes of osteoporosis fractures. There are over 700,000 VCF patients yearly. Percutaneous kyphoplasty (PKP) is a minimally invasive surgical approach that uses interventional radiology technique and involves the fluoroscopically guided injection of polymethylmethacrylate (PMMA) through a needle inserted into a weakened vertebral body. In China, with no randomized controlled study reported in this regard, it is still controversial to choose between PKP and conservative treatment for VCF patients.

Polymethylmethacrylate dermal fillers: evaluation of the systemic toxicity in rats

This study evaluated local and systemic reactions after an intravascular injection of polymethylmethacrylate (PMMA) at two concentrations in a murine model. Thirty rats were divided equally into three groups: 2% PMMA, 30% PMMA, and a control group (normal saline only injection). The filler was injected into the ranine vein. The rats were sedated at 7 and 90 days and a clinical evaluation performed. After euthanasia, the right lung, liver, and right kidney were removed, weighed, and microscopically analyzed. The submandibular lymph nodes and tongue were removed and examined microscopically. Serum was subjected to liver and kidney function tests. No groups showed clinical alterations. Microspheres were not observed at any distant organ. Two samples from the 2% PMMA group showed a local inflammatory response at day 7 and another two samples from the 30% PMMA group at day 90. The group injected with 30% PMMA presented higher levels of alanine aminotransferase (P=0.047) after 90 days when compared with the other groups. The data obtained in this study demonstrate that intravascular injections of PMMA fillers show potential health risks such as chronic inflammation at the implantation site.

The Use of Advanced Imaging and Representation of Workers Compensation in Vertebral Augmentation: A Single-Center Comparison with the INVEST Trial

Background: Vertebral augmentation (VA) techniques have changed the paradigm of treatment during the past decade and involve injection of polymethylmethacrylate (PMMA) cement directly into a compressed vertebral body. During the summer of 2009, the INVEST trial was one of 2 randomized controlled studies that reported equivalence between vertebroplasty and a control procedure. Objective: In this analysis, we sought to compare the subset of patients studied in the INVEST trial to a tertiary academic institution with respect to 2 variables: Workers compensation status and presence of advanced imaging prior to the procedure. Study Design: Retrospective review of 634 procedures. Methods: We performed a retrospective review of 634 vertebral augmentation procedures at our institution between June 2004 and August 2008, overlapping with the dataset of the INVEST trial. The primary comparison was whether patients received Workers compensation and/or advanced imaging prior to the procedure. The study was IRB approved, and in accordance with HIPAA guidelines. Results: There were 409 patients who underwent 634 procedures between June 2004 and August 2008. Among 634 procedures, only 3 included Workers compensation. Therefore, the majority of patients (&gt; 99%) did not receive Workers compensation compared to the INVEST trial (11 – 13%). Similarly, in 629 out of 634 procedures (99.2%), patients underwent advanced imaging comprised of magnetic resonance imaging (MRI), computed tomography (CT) or bone scan. Limitations: We simply looked at 2 elements of the patient demographic in a time-matched fashion and compared it to the U.S. based INVEST trial. It is possible that despite our diligent efforts to review the data set, we have inadvertently excluded some patients, the incorporation of whom might have changed the statistics. Conclusion: We reviewed our time-matched database in terms of 2 variables we thought curious in the INVEST trial. In comparison to our practice, where advanced imaging is essentially required and Workers compensation largely not seen, these aspects of the INVEST trial’s population stood out. Key words: Spinal fractures/therapy, vertebroplasty/methods, kyphoplasty, evidence-based medicine, pain management, treatment outcome