PMMA Injection Research Articles

FRI695 Hypercalcemia Mediated By Granulomatous Disease Due To Polymethylmethacrylate (pmma) Injection Utilization For Gluteal Augmentation

Abstract Disclosure: T. Mishra: None. J. Craven: None. Introduction: While etiologies for hypercalcemia commonly include hyperparathyroidism, malignancy or vitamin D intoxication, unusual causes should also be considered. We present a case that describes a patient who presented with hypercalcemia in the setting of granulomatous reaction to PMMA filler for gluteal augmentation. Clinical case: A 52 year old female with a past medical history of hypertension, stage III chronic kidney disease, nephrolithiasis, depression was admitted to the hospital with a peak calcium of 15.8 mg/dl (n: 8.4-10.4mg/dl). Hypercalcemia was incidentally noted while she was undergoing workup for her chronic kidney disease. Initial testing revealed PTH of 22 pg/ml (n: 22-94). 25 hydroxy vitamin D 24ng/ml, (n: 30-80), 1, 25 dihydroxy D2 markedly elevated at 258 pg/ml (n: 19-79). SPEP/UPEP normal. PTHrp was found to be 5.9 pmol/L(n: 0-3.4pmol/L). High-resolution CT chest did not show evidence of granulomatous disease or lung masses. A PET scan was obtained which showed extensive hypermetabolic activity in the bilateral gluteus medius and maximus muscle consistent with her history of PMMA injection for buttock augmentation. She was placed on aggressive maintenance intravenous fluid hydration. In addition, Lasix, zoledronic acid and calcitonin were administered. With these measures her calcium improved to a level of 10.7mg/dl. She did not tolerate high dose glucocorticoids. With her treatment intolerance and progressive renal disease in mind, plastic surgery has been consulted to explore surgical options for PMMA debulking. Conclusion: This represents a case of hypercalcemia mediated by elevated levels of calcitriol due to granulomatous inflammation caused by a foreign body reaction to PMMA injection. Polymethylmethacrylate is primarily used in South/Central America as a synthetic filling agent in cosmetic procedures, but is not FDA approved for gluteal injection. To our knowledge, there is only one other case report of MMA mediated hypercalcemia in the US. Given the rise in cosmetic tourism and the lag time between PMMA injection and development of hypercalcemia (mean time to presentation of 7 years), this complication is likely to become increasingly prevalent in North America. Presentation: Friday, June 16, 2023

A Novel Semi-Cannulated Screw Enhanced Bone Cement Augmentation and Pullout Strength in Posterior Cervical Lateral Mass Screw Fixations: An In Vitro Biomechanical and Morphological Study.

To develop a novel semi-cannulated lateral mass screw (SC-LMS) for cervical posterior fixations and compare the fixation stability and safety of SC-LMS with regular solid lateral mass screw (S-LMS) in bone cement augmentation and pullout strength using fresh cadaveric cervical vertebrae. The conventional multiaxial screw for cervical lateral mass fixation was modified to a cannulated screw with two lateral holes, used for bone cement injection in situ. Eight fresh human cervical vertebrae (C3, C4, and C5) were collected and used. μCT scan was performed to evaluate the bone quality of the lateral masses, including bone mineral density (BMD), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp). SCLMS or S-LMS were randomly inserted into the paired cervical vertebrae and pulled out as a screw loosening model. These screws were reinserted in with bone cement augmentation, scanned by μCT to obtain the bone cement distribution along the screws, and pulled out to test the screw purchase strength. Fmax values exhibited strong positive correlations with the local BMD (𝑟 = 0.8640, p < 0.0001) and Tb.Th (𝑟 = 0.6795, p = 0.0038), whereas a negative correlation with Tb.Sp (𝑟 = -0.5567, p = 0.0251). A significant difference was observed between the Fmax before and after PMMA injection on the SC-LMS side (p = 0.019). The SC-LMS exhibited lower risk of cement leakage than S-LMS after PMMA injection, and a positive correlation was observed between 𝐹max and the distribution volumes on the SC-LMS side. The novel SC-LMS provides more robust fixation stability and is safer than the S-LMS for PMMA augmentation, which may be related to the cement-screw-cement-bone complex formation.

Injection of New PMMA* Loaded Microspheres into Anterior Chamber to Establish a Rabbit Glaucoma Model

Objective: To develop a novel PMMA material microsphere and characterize it. Named it PMMA*.The microsphere was loaded with drugs, and the intraocular pressure of rabbits was increased by anterior chamber injection, so as to establish a new animal model of ocular hypertension. Methods: PMMA* microspheres with a diameter of 50-80μm were prepared, and the drug loading, release and biosafety of PMMA* microspheres were analyzed. PMMA* microsphere suspension was prepared at 1% dosage of atropine sulfate. Eighteen healthy male New Zealand white rabbits were selected, with the right eye as the experimental eye and the left eye as the control eye. They were randomly divided into blank microsphere group, atropine sulfate group and atropine sulfate loaded microsphere group with 6 rabbits in each group. The chronic ocular hypertension model of the right eye was established. Intraocular pressure was monitored postoperatively and Micro-CT was used to determine the position of the microsphere at the anterior chamber Angle. The pathological changes of chronic glaucoma were studied. Results: PMMA* microspheres have the characteristics of micropore structure, adjustable size, slow release, in situ residence and good biosafety. There was no significant difference in preoperative intraocular pressure in rabbits (P>0.05), which was comparable. At 15 days after surgery, the intraocular pressure in experimental eyes was significantly higher than that in control eyes, with statistical significance (P<0.05), and the increase of intraocular pressure caused by drug-loaded PMMA* microspheres was more significant. Micro-CT determined the position of the microsphere in the anterior chamber Angle of rabbit. The atropine sulfate loaded microspheres showed more obvious ganglion cell - retinal nerve fiber layer damage. Conclusions:The PMMA* microspheres synthesized in this study have good drug loading performance and slow release performance. Intraventral injection of drug-loaded PMMA* microspheres can block the outflow of aqueous solution to establish a better chronic glaucoma model.

지르코니아 나노입자 기반 나노패턴 금속 몰드 제작과 열가소성 재료의 복제성형 응용

Fabrication of a durable and strong nanopatterned mold insert using metal sheet and plate is important for molding of thermoplastic materials. Conventionally, the nickel stamper replicating a master pattern by electroforming process has been used for injection molding of nanotextured products such as Blu-ray media. However, a more facile and cheaper mold fabrication process is highly required for manufacturing of functional products based on nanostructured surface. In this study, zirconia nanoparticles were blended with UV curing polymer to fabricate a polymer nanocompositebased nanopattern mold. Compared to the cured pure Ormostamp, the modulus of elasticity of the nanocomposite filled with approximately 54 vol% of zirconia nanoparticles increased by 160 times. Additionally, the modulus of elasticity reached 197 ㎬ by thermal decomposition of the UV-Cured polymer and post-annealing at 800°C of the nanoparticle layer. The nanopatterns were formed on stainless steel sheet and block, and applied to hot embossing of the PMMA films and injection molding of the COC materials, respectively. No deterioration of the mold occurred during the hot embossing 30 times and the injection molding 600 shots. Nanoparticle-enhanced UV curing nanocomposites or post-heat treatment methods are cost-efficient and easy, because many molds can be manufactured from one master pattern.

Risk factors of neurological deficit and pulmonary cement embolism after percutaneous vertebroplasty

BackgroundThe risk factors, incidence, and clinical management of pulmonary cement embolism and neurological deficit during percutaneous vertebroplasty (PVP) were evaluated.MethodsThree thousand one hundred and seventy-five patients with symptomatic osteoporotic vertebral compression fractures (OVCFs) treated with PVP were retrospectively reviewed in a single institution. Clinical parameters such as age, gender, number of fractures, and time from fracture to vertebroplasty were recorded at the time of surgery. Image and surgical parameters including the amount of cement, the vertebral level, uni- or bipedicle surgical approach, and leakage pattern were recorded.ResultsType-C leakage, including paraspinal (25%), intradiscal (26%), and posterior (0.7%) leakage, was more common than type-B (11.4%) and type-S leaks (4.9%). Cement leakage into the spinal canal (type-C posterior) occurred in 26 patients (0.7%), and four patients needed surgical decompression. Three in nine patients with leakage into thoracic spine needed decompressive surgery, but only one of 17 patients into lumbar spine needed surgery (p < 0.01). Age, gender, number of fractures, and time from fracture to vertebroplasty were not risk factors of pulmonary cement embolism or neurological deficit. The risk factor of pulmonary cement embolism was higher volume of PMMA injected (p < 0.001) and risk factor of neurological deficit was type-C posterior cement leakage into thoracic spine. The incidence of pulmonary cement embolism was significantly high in the volume of PMMA injected (PMMA injection < 3.5 cc: 0%; 3.5–7.0 cc: 0.11%; > 7.0 cc: 0.9%; p < 0.01) which needed postoperative oxygen support.ConclusionsCement leakage is relatively common but mostly of no clinical significance. Percutaneous vertebroplasty in thoracic spine and high amount of PMMA injected should be treated with caution in clinical practice.

Less PMMA Injection as an Independent Factor for Poor Neurologic Recovery in Malignant Vertebral Compression Fractures With Symptoms of Neurologic Compression Following Percutaneous Vertebroplasty

Background: Recent years, percutaneous vertebroplasty (PVP) has gained wide clinical acceptance as an effective treatment option for patients with intractable pain related to compression fractures of the spine. But little is known about PVP for spinal malignant lesions with epidural involvement in patients with neurologic deficit. Aim: To evaluate the efficacy of PVP for malignant vertebral compression fractures with symptoms of neurologic compression following percutaneous vertebroplasty (PVP), and evaluate the predictive factors for poor outcomes following PVP. Methods: Forty-three patients with malignant vertebral compression fractures with symptoms of neurologic compression were treated with PVP. Patients were classified into 2 groups according to the American Spinal Injury Association (ASIA) impairment scale at the last follow-up. Data were collected and the patients followed-up at 1, 3, 6 and 12 months and yearly after the procedure. Univariate and multivariate analysis was performed to evaluate factors predictive of poor neurologic compression symptoms recovery. Results: PVP were successful in all patients. Full recovery from (n = 2) or improvement of (n = 16) neurologic compression symptoms were achieved in 18 patients (Group A), and no improvement of neurologic compression symptoms in 25 patients (Group A). Univariate analysis showed more PMMA leakage ( P = 0.038) and less PMMA volume injection ( P &lt; 0.001) was associated with the poor symptoms of neurologic compression recovery, and multivariate analysis showed that less PMMA volume injection ( P = 0.004) was an independent predictor for poor symptom of neurologic compression recovery. Conclusion: Our results indicated PVP should not be served as an effective treatment of malignant compression fractures with symptoms of neurologic compression, and less PMMA volume injection was an independent predictor of poor symptom of neurologic compression recovery.

Erratum: Less PMMA Injection as an Independent Predictor of Poor Neurologic Recovery Following Percutaneous Vertebroplasty in Patients with Malignant Vertebral Compression Fractures [Journal of Hard Tissue Biology 26(4) Vol.26, 2017, pp 411-416

Erratum: Less PMMA Injection as an Independent Predictor of Poor Neurologic Recovery Following Percutaneous Vertebroplasty in Patients with Malignant Vertebral Compression Fractures [Journal of Hard Tissue Biology 26(4) Vol.26, 2017, pp 411-416

Less PMMA Injection as an Independent Predictor of Poor Neurologic Recovery Following Percutaneous Vertebroplasty in Patients with Malignant Vertebral Compression Fractures

Less PMMA Injection as an Independent Predictor of Poor Neurologic Recovery Following Percutaneous Vertebroplasty in Patients with Malignant Vertebral Compression Fractures

Surgical approach to multiple foreign body granulomas (PMMA)

Injectable fillers have long been used for cosmetic purposes and in HIV induced lipodystrophy patients. A foreign body granuloma may be a side effect of the application of absorbable products/temporary and most often the nonabsorbable/permanent fillers. It is not possible to predict the formation of these granulomas, and it may occur regardless of the application technique. In this article we describe the surgical treatment of a patient with multiple granulomas caused by intradermal injection of PMMA in the face, with poor response to conservative treatments, and severe psychosocial impairment due to this unsightly and disfiguring complication.

Mini-Invasive Treatment of Monolevel Dorsolumbar Metastatic Lesions by Radio Frequency Ablation and Augmentation: Preliminary Experience in a Series of 10 Cases

Introduction Technological advances have allowed the development of several “minimally invasive” surgical techniques in the treatment of metastatic spinal tumors. The authors analyzed the effectiveness and impact on quality of life in the short and medium term using radiofrequency ablation and injection of PMMA in the treatment of chronic low back pain in a series of 10 patients suffering from a monolevel metastatic lesion of the dorsolumbar spine. Patients and Methods In 2013, at our Department, 10 patients affected by dorsolumbar monolevel metastatic lesion, in advanced disease, were selected to undergo treatment of transpedicle radio frequency ablation and injection of PMMA. Overall, nine patients were treated by percutaneous technique as they had an already known and suitably treated primary lesion, good performance status, chronic low back pain (mean low back VAS: 8.5), no neurological deficit. Only one patient came to our observation for the presence of low back pain and progressive weakness in the lower limbs, in the absence of already known primitive tumor. In this case, an open surgery with decompression, posterior fusion, and then ablation with augmentation was performed. Results Patients treated percutaneously showed an improvement in pain symptoms with a significant reduction in the VAS (post-op VAS: 3.5) in the absence of new-onset neurological deficit. The patient treated in “open surgery” had a reduction in pain with improvement of neurological function of the lower limbs making it possible walking. All the patients were sent to the oncologist for medical care. Conclusions The radiofrequency thermocoagulation with injection of PMMA seems a good strategy, as palliative treatment, in patients with metastatic advanced disease, with low back pain in the absence of significant neurological deficit when suffering from single level metastatic somatic lesion, ensuring both the effectiveness because of the neoplastic tissue ablation and the augmentation. This allows a gain of QOL in critically ill patients in terms of reduction of pain symptoms.

A Novel Approach for Horizontal Sacral Insufficiency Fractures. Long Axis Kyphoplasty through Sacral Hiatus

Introduction Sacral insufficiency fractures (SIF) may cause significant low back pain, limit daily living, and tend to be undetected. Effective pain management and early mobilization are mandatory to prevent complications. Percutaneous sacroplasty for treatment of SIF has gained interest recently. This technique provides safe, rapid, and prolonged pain relief, early mobilization, and functional recovery. Sacral kyphoplasty is percutaneous placement of bone cement into the sacral vertebra using inflatable tamps. Both sacroplasty and sacral kyphoplasty are used for vertical component of the SIF. Highly trabecular pattern of sacral bone and proximity of sacral foramina and sacral canal limit the use of these techniques to sacral ala. We have described a new technique for injection of PMMA into proximal sacral vertebra. Patient and Methods: A 50-year-old patient with SIF at S1–S2 level was selected for this procedure. The patient was placed prone on the operation table. She was sedated using IV midazolam and fentanyl. The fluoroscopy was positioned so that sacral foramina could be clearly visualized on AP and lateral views. A stab incision was made following local anesthesia at the level of sacral hiatus. Bone access needle was introduced into the sacral hiatus above the superior margin of the coccyx under fluoroscopic guidance, similar to epiduroscopy. Epidural space was traversed and the corpus of distal sacral vertebra was reached. Entry point was checked in AP and lateral views. Needle tip was advanced proximal to the fracture line, into the S1. Once the ideal position of the needle was confirmed, guide pin and a working cannula were inserted. Balloon tamp was inserted and was inflated with 1.5 mL contrast dye to no more than 250 psi. Fluoroscopic control was performed to make sure that the inflated balloon did not breach cortices. Bone tamps were deflated and removed. The void was filled with radio opaque bone cement proximal to distal as cannula was slowly pulled back. Migration and extravasation of the cement was checked with fluoroscopy. Results The surgical procedure was completed in 25 minutes. Total fluoroscopy time was 10 minutes. There were no intraoperative or postoperative complications. While in the PACU, the patient declared that her pain had alleviated by half. She could mobilize freely in her room 2 hours after the intervention. No cement extravasation occurred. 24 hours following the surgery, she was completely pain free and was discharged from the hospital. On her last follow-up, she was completely asymptomatic, ambulatory, and could perform her daily activities by herself. Conclusion Sacroplasty and sacral kyphoplasty are generally used for Denis Zone 1 fractures. Proximity of the sacral foramina and sacral canal cause clinicians to avoid cement injection into sacral vertebral bodies. This procedure is very rarely performed. Use of pedicles to reach vertebral corpus restricts surgeon's ability to position cannula and pedicle fracture is another risk. With our long axis technique, bone cement can be injected into the sacral body in a longitudinal fashion with multiple sacral levels being augmented in a single entry.

Vertebroplasty of cervical vertebra.

SummaryBackgroundThe first vertebroplasty was performed by Harve Deramond in France in 1984 due to a hemangioma of cervical vertebral body. Procedure technique consisted of inserting a needle through the bony palate of the oral cavity. Bone cement injected under pressure not only fills the areas of bone loss. The heat released in the process of crystallization causes denaturation of pathological tissue proteins (metastasis) and disrupts blood supply (hemangiomas). The aim of this study was to evaluate the method of treatment from anterolateral access.Material/MethodsIn the years 2007–2012 the procedure was performed in 6 men and 9 women aged from 42 to 71 years (mean age: 56.3 years). In 10 cases the reason for vertebroplasty was the vertebral hemangioma, in another 4 – pathological vertebral fractures due to metastases, and in one case – multiple myeloma. Procedures were performed from anterolateral access, under local anesthesia, under x-ray guidance (fluoroscopy). Bone needle was inserted into the vertebral body, followed by injection of PMMA cement.ResultsIn 100% cases pain relief was observed immediately after the procedure and beneficial therapeutic effect was obtained. No life-threatening complications and clinical symptoms were observed. Average length hospital stay amounted to 2.9 days.ConclusionsCervical spine vertebroplasty from anterolateral access seems to be a safe, effective and beneficial method of treatment. It reduces the risk of infection in comparison to the transoral method.

PMMA-augmentation of incompletely cannulated pedicle screws: a cadaver study to determine the benefits in the osteoporotic spine.

Pedicle screw pullout due to poor bone quality, mainly caused by osteoporosis, is a common problem in spine surgery. Special implants and techniques, especially PMMA augmentation, were developed to improve the fixation of pedicle screws. PMMA injection into a pilot hole or through a screw involves the same risks as vertebroplasty or kyphoplasty, regardless of the technique used. Especially when using fully cannulated screws anterior leakage is possible. To prove PMMA injection is safe and possible without leakage through an incompletely cannulated screw and also increases pullout forces in the osteoporotic vertebra. Incompletely cannulated pedicle screws were tested by axial pullout in human cadavers, divided into osteoporotic and non-osteoporotic groups. Non-augmented and PMMA-augmented pedicle screws were compared. Twenty-five human vertebrae were measured by DEXA and divided into osteoporotic and non-osteoporotic groups. In each vertebra both pedicles were instrumented with the new screw (WSI-Expertise 6×45 mm, Peter Brehm Inc. Germany); the right screw was augmented with a 3 mL PMMA injection through the screw. On each screw axial pullout was performed after X-ray and CT scan. Radiographs and CT scans excluded PMMA leakage. Cement was distributed in the middle and posterior third of the vertebrae. Pullout forces were significantly higher after pedicle screw augmentation, especially in the osteoporotic bone. All augmented pedicle screws showed higher pullout forces compared with the unaugmented screws. We minimized the risk of leakage by using a screw with a closed tip. On the whole, PMMA augmentation through an incompletely cannulated pedicle screw is safe and increases pullout forces in osteoporotic bone to the level of healthy bone. Therefore the new incompletely cannulated screw can be used for pedicle screw augmentation.

Clinical Measurement of Intravertebral Pressure During Vertebroplasty and Kyphoplasty

Background: Vertebroplasty (VP) and kyphoplasty (KP) are emerging procedures for almost immediate pain relief when treating osteoporotic or osteolytic fractures. The main reported complication is polymethylmethacrylate (PMMA) leakage, which may lead to compression of neural structures or embolism. Different authors have proposed that intravertebral pressure (IP) is an important factor determining the risk for leakage, although so far only limited information has been gathered from clinical and experimental studies. There is also a lack of understanding of the IP during conventional interventions in VP and KP in the clinic. Objective: 1) To compare the intravertebral pressures of compressed vertebrae and adjacent normal vertebrae. 2) To measure the IP of compressed vertebrae during VP and KP. Setting: An interventional pain management practice, a medical center, major metropolitan city, in the People’s Republic of China. Methods: Thirty-five patients (with 40 compressed vertebrae and 35 adjacent normal vertebrae) were randomly allocated for intravertebral pressure measurements. Cannulas were placed bipedicularly into the posterior third of each vertebral body. Either PMMA or a balloon was injected into the vertebral body through the right cannula. A manometer was connected to the cannula in the left pedicle, and heparin was injected to verify the pressure measurement system. Results: The range (minimum-maximum), average IP, and the standard deviation of the compressed vertebrae were 0-39 mm Hg and 24.5 ±11.3 mm Hg; and that of adjacent normal vertebrae were 3-16 mm Hg, 7.3 ± 4.2 mm Hg. Furthermore, the average IP for Phase 1 (before PMMA injection) for VP was 23 ±11.9 mm Hg; the maximum IP recorded during injection was 169 ± 46.8 mm Hg and the IP for 10 minutes after injection was 33 ±9.4 mm Hg. Meanwhile, the highest IP recorded for KP patients was 142 ±39.6 mm Hg. The average IP for Phase 1 (before balloon inflation) was 24 ±12.7mmHg; Phase 2 (peak IP during the balloon inflation) was 63 ± 25.8 mm Hg; and Phase 3 (after balloon inflation/before PMMA injection) was , and 18 ± 10.8 mm Hg. The IP for 10 minutes after injection in KP patients was 36 ± 8.5 mm Hg. Limitations: The flow rate was manually controlled, which is in line with clinical routine, and was kept at approximately 0.1 mL/s. Because the speed of injection was controlled by hand, an exact injection rate could not be assured, leading to some inaccuracy when comparing the IP of VP and KP patients. Each patient was injected with a different PMMA volume. Because PMMA injection was performed to a satisfactory vertebral body filling and limited by any signs of extravasation, it was difficult to maintain a constant injection volume, unlike in vitro studies. Other factors such as the damage to the vertebral shell or the degree of osteoporosis might also have affected the intravertebral pressure. Conclusion: This study showed that the IP of compressed vertebrae was significantly higher than that of adjacent normal vertebrae. There was a significant increase in IP during the PMMA filling in VP and KP; the IP of compressed vertebrae was not significantly reduced by the balloon inflation in KP, and no statistically significant differences in IP were found during all common stages of PMMA filling in VP and KP. Key words: Vertebroplasty, kyphoplasty, intravertebral pressure, PMMA leakage.

Analysis of the correlation between bone cement distribution and vertebral refracture after lumbar percutaneous vertebroplasty kyphoplasty

Objective To research the risk of osteopo'rotic vertebral fractures with PKP after the PMMA injected location and dose of occurrence of vertebral refracture.Methods 78 cases of vertebral osteoporotic thoracolumbar vertebral compression fracture patients with PKP treatmentin were selected.According to position of postoperative PMMA in the vertebral body,they were divided into the side of the group of 35 patients and a median group of 43 patients.Compared two groups of patients before and after surgery,VAS,ODI score,the SI and Cobb angle and analyzed the PMMA leakage occur with the relationship of the amount of bone cement injected.Results There were significant differences in visual analogue pain scale(VAS),Oswestry disability index(ODI),sagittal index(SI) and Cobb angle of each group preoperatively versuspostoperatively (all P ＜ 0.05).No statistical difference was noted in the VAS,ODI,SI and Cobb angle between two groups preoperatively versus postoperatively(all P ＞ 0.05).PMMA injection volume between the the leakage group and the non-leakage patients had statistically significant difference (P ＜ 0.05).Conclusion PKP could obtain better clinical therapeutic effect in osteoporotic vertebral fractures treatment.Different PMMA positions had no significant influence on the therapeutic results.PMMA injected dose is a risk factor for bone cement leakage,which will increase the risk of vertebral fractures again. Key words: Spine; Osteoporosis ; Fracture, compression; Vertebroplasty; Calcium phosphate

Related Biological Research in the Interface between Bone Cement and Bone after Percutaneous Vertebroplasty

Percutaneous vertebroplasty (PVP) is widely used in the treatment of painful osteoporotic vertebral compression fractures with the injection of PMMA cement, and the controversy for PMMA damage to the osteoporotic bone tissue and to affect the fractures repairing never stops. 72 old female rabbits, each age 3.0~3.5 y, rabbits were assigned randomly to two groups of thirty-six each; PMMA cement were injected into vertebral body in rabbits via mimic PVP, sacrificed at 1 h, 24 h, 3 d, 7 d, 4 w, and 12 w. The expression VEGF and collagen type I, the tissue response, and repair reaction in the interface between PMMA and bone tissue were observed dynamically with RT-PCR and western blot technique; the osteocalcin expression were studied by immunohistochemistry. Compared with the control group, the expression of collagen I increased at 1 hour and was higher from 24 h to 3 d. From 4 weeks to 12 weeks after injection of PMMA. The expression of VEGF decreased at 1 hour and 24 hours, significantly increased at 3 days, decreased once again at 7 days, then increased significantly at 4–12 weeks. The osteocalcin expression continued to increase during 4 to 12 week. PMMA would not cause local bone permanent necrosis, and interface injury repairing cycle could be prolonged in a vertebroplasty.

Possible Migration and Histopathological Analysis of Injections of Polymethylmethacrylate in Wistar Rats

Objective. To evaluate the possible migration of polymethylmethacrylate after injections in various corporal compartments of Wistar rats. Methods. The experimental work consisted in the injection of PMMA in corporal compartments for later histopathological analysis of the locations of implants and of distant filtering organs. The dose applied in each implant was of 0.2 mL. The animals were divided into groups according to the location of the implant realized: group GB had intradermic injections in the glabella. Group SD had subdermal injections in dorsal subcutaneous tissue cells. Group IP had intraperitoneal injections in the abdomen. Group PD had intramuscular injections in the right rear leg. The rats were sacrificed 30 days after realization of the implants and tissue samples from the lung, liver, spleen, and kidney, and locations of implantation were removed for histopathological analysis. Results. Characteristic microspheres that were compatible with the presence of PMMA in any of the histological slides analyzed were not observed. One animal had an amorphous exogenous substance, with a histiocytic reaction. Twelve of the 16 lungs analyzed had locations of intraalveolar hemorrhaging. Two animals had nonspecific spleen alterations. Conclusion. The histopathological analysis of this study found no PMMA microspheres in any of the tissues analyzed.

32. A New Device for Percutaneous Vertebral Re-Expansion: Preliminary Experience on 23 Patients for Magerl Type A Traumatic Burst Fracture

BACKGROUND CONTEXT: Treatment of thoracolumbar stable burst fractures classically requires bed resting and bracing. Recently, balloon kyphoplasty has been proposed for acutely fractured vertebrae to increase vertebral height restoration compared to orthopedic treatment. We propose a new minimally invasive technique for vertebral re-expansion using a permanent vertebral cranio-caudal expandable implant (VCCEI) combined with PMMA injection. The goal of this technique is to provide optimal height restoration, as well as strong enough vertebral support to avoid bracing and allow quick discharge.

A Prospective Randomized Trial Of Core Decompression With Or Without Cement Packing For Pre-Collapse Osteonecrosis Of The Femoral Head – Long Term Results

Osteoneocrosis of the femoral head (ONFH) is difficult to treat as collapse frequently occurs despite core decompression (CD), probably due to the failure to provide structural support. Reports of PMMA injection for ONFH have noted favourable results. This study was undertaken to determine whether the addition of PMMA packing, provides any benefit to the outcomes of CD.

Histological and radiographic evaluation of polymethylmethacrylate with two different concentrations of barium sulfate in a sheep vertebroplasty model

Percutaneous vertebral augmentation with PMMA has been widely performed and usually provides good pain relief and stabilization of fractured vertebrae. Adequate visualization of PMMA during injection is desirable to minimize cement extravasation, so contrast agents such as barium sulfate are commonly added to the PMMA. The aim of this study was to evaluate the differences of histology and radiographic visualization when different concentrations of barium sulfate are mixed with PMMA. Six sheep were utilized in this study. Three vertebrae of each animal were exposed via retroperitoneal approach, and a cavity was created and then filled with either 10% or 30% BaSO4/PMMA, or left empty. Vertebrae were harvested and analyzed radiographically and histologically 12 and 90 days after surgery. Average CT value of the 30% BaSO4/PMMA group was 2.4-fold higher than that of the 10% BaSO4/PMMA group. Foreign-body giant cells were recognized around BaSO4particles at 90 days in the 30% BaSO4 group, whereas few particles were recognized in the 10% group at 90 days, or in either group at 12 days. A very mild giant-cell reaction is induced by a higher concentration of BaSO4 in PMMA, but the marked improvement in cement visualization by increased BaSO4 may be important to minimize more serious complications of cement extravasation during PMMA injection.