We developed a novel silorane-based biomaterial (SBB) for use as an orthopedic cement. SBB is comprised of non-toxic silicon-based monomers, undergoes non-exothermic polymerization, and has weight-bearing strength required of orthopedic cements. We sought to compare the antibiotic release kinetics of this new cement to that of commercially available PMMA bone cement. We also evaluated each material's inherent propensity to support the attachment of bacteria under both static and dynamic conditions. One gram of either rifampin or vancomycin was added to 40g batches of PMMA and SBB. Pellets were individually soaked in PBS. Eluate was collected and tested daily for 14 days using HPLC. Compressive strength and modulus were tested over 21 days. Bioassays were used to confirm the bioactivity of the antibiotics eluted. We measured the growth and maturation of staphylococcus aureus (SA) biofilm on the surface of both PMMA and SBB disks over the course of 72 hours in a static well plate and in a dynamic biofilm reactor (CDC Biofilm Reactor). N=4 at 24, 48, and 72 hours. A luminescent strain of SA (Xen 29) was employed allowing imaging of bacteria on the discs. SBB eluted higher concentrations of vancomycin than did PMMA over the course of 14 days (p<0.001). A significant 55.1% greater day 1 elution was observed from SBB. Silorane cement was able to deliver rifampin in clinically favorable concentrations over 14 days. On the contrary, PMMA was unable to deliver rifampin past day 1. The incorporation of rifampin into PMMA severely reduced its mechanical strength (p<0.001) and modulus (p<0.001). Surface bacterial radiance of PMMA specimens was significantly greater than that of SBB specimens at all time points (p<0.05). The novel silorane-based cement demonstrated superior antibiotic release and, even without antibiotic incorporation, demonstrated an innate inhabitation to bacterial attachment and biofilm

The pathogenesis of aseptic loosening of total joint prostheses is not clearly understood. Two features are associated with loosened prostheses, namely, particulate debris and movement of the implant. While numerous studies have evaluated the cellular response to particulate biomaterials, few have investigated the influence of movement of the implant on the biological response to particles. Our aim was therefore to test the hypothesis that excessive mechanical stimulation of the periprosthetic tissues induces an inflammatory response and that the addition of particulate biomaterials intensifies this. We allocated 66 adult Beagle dogs to four groups as follows: stable implants with (I) and without (II) particulate polymethylmethacrylate (PMMA) and moving implants with (III) and without (IV) particulate PMMA. They were then evaluated at 2, 4, 6, 12 and 24 weeks. The stable implants were well tolerated and a thin, fibrous membrane of connective tissue was observed. There was evidence of positive staining in some cells for interleukin-6 (IL-6). Addition of particulate PMMA around the stable implants resulted in an increase in the fibroblastic response and positive staining for IL-6 and tumour necrosis factor-alpha (TNF-α). By contrast, movement of the implant resulted in an immediate inflammatory response characterised by large numbers of histiocytes and cytokine staining for IL-1ß, TNF-α and IL-6. Introduction of particulate PMMA aggravated this response. Animals with particulate PMMA and movement of the implant have an intense inflammatory response associated with accelerated bone loss. Our results indicate that the initiation of the inflammatory response to biomaterial particles was much slower than that to gross mechanical instability. Furthermore, when there was both particulate debris and movement, there was an amplification of the adverse tissue response as evidenced by the presence of osteolysis and increases in the presence of inflammatory cells and their associated cytokines

Osteosarcoma and other types of bone cancers often require bone resection, and backfill with cement. A novel silorane-based cement without PMMA's drawbacks, previously developed for dental applications, has been reformulated for orthopedic use. The aim of this study is to assess each cement's ability to elute doxorubicin, maintain its potency, and maintain suitable weight-bearing strength. The silorane-based epoxy cement was synthesized using a platinum-based Lamoreaux's catalyst. Four groups of cement were prepared. Two PMMA groups, one without any additives, one with 200 mg of doxorubicin. Two silorane groups: one without any additive, one with doxorubicin, added so that the w% of drug into both cements were equal. Pellets 6 × 12 mm were used for testing (ASTM F451). n=10. Ten pellets from each group were kept dry. All others were placed into tubes containing 2.5 mL of PBS and stored at 37 °C. Elution from doxorubicin-containing groups were collected every day for 7 days, with daily PBS changeout. Antibiotic concentrations were determined via HPLC. Compressive strength and compressive modulus of all groups were determined for unsoaked specimens, and those soaked for 7 and 14 days. MTT assays were done using an MG63 osteosarcoma cell line. Both cements were able to elute doxorubicin over 7 days in clinically-favorable quantities. For PMMA samples, the incorporation of doxorubicin was shown to significantly affect the compressive strength and modulus of the samples (p<0.01). Incorporation of doxorubicin into silorane had no significant effect on either (p>.05). MTT assays indicated that doxorubicin incorporated into the silorane cement maintained its effectiveness whereas that into PMMA did not. At the dosing used, both cements remained above the 70 MPa. Both PMMA and silorane-based cements can deliver doxorubicin. Doxorubicin, however, interacts chemically with PMMA, inhibiting polymerization and lowering the chemotherapeutic's effectiveness

Treatment of bone infection often includes a burdensome two-stage revision. After debridement, contaminated implants are removed and replaced with a non-absorbable cement spacer loaded with antibiotics. Weeks later, the spacer is exchanged with a bone graft aiding bone healing. However, even with this two-stage approach infection persists. In this study, we investigated whether a novel 3D-printed, antibiotic-loaded, osteoinductive calcium phosphate scaffold (CPS) is effective in single-stage revision of an infected non-union with segmental bone loss in rabbits. A 5 mm defect was created in the radius of female New Zealand White rabbits. The bone fragment was replaced, stabilized with cerclage wire and inoculated with Staphylococcus aureus (MSSA). After 4 weeks, the infected bone fragment was removed, the site debrided and a spacer implanted. Depending on group allocation, rabbits received: 1) PMMA spacer with gentamycin; 2) CPS loaded with rifampin and vancomycin and 3) Non-loaded CPS. These groups received systemic cefazolin for 4 weeks after revision. Group 4 received a loaded CPS without any adjunctive systemic therapy (n=12 group1-3, n=11 group 4). All animals were euthanized 8 weeks after revision and assessed by quantitative bacteriology or histology. Covariance analysis (ANCOVA) and multiple regression were performed. All animals were culture positive at revision surgery. Half of the animals in all groups had eliminated the infection by end of study. In a historical control group with empty defect and no systemic antibiotic treatment, all animals were infected at euthanasia. There was no significant difference in CFU counts between groups at euthanasia. Our results show that treating an osteomyelitis with segmental bone loss either with CPS or PMMA has a similar cure rate of infection. However, by not requiring a second surgery, the use of CPS may offer advantages over non-resorbable equivalents such as PMMA

Residual tumor cells left in the bone defect after malignant bone tumor resection can result in local tumor recurrence and high mortality. Therefore, ideal bone filling materials should not only aid bone reconstruction or regeneration, but also exert local chemotherapeutic efficacy. However, common bone substitutes used in clinics are barely studied in research for local delivery of chemotherapeutic drugs. Here, we aimed to use facile manufacturing methods to render polymethylmethacrylate (PMMA) cement and ceramic granules suitable for local delivery of cisplatin to limit bone tumor recurrence. Porosity was introduced into PMMA cement by adding 1-4% carboxymethylcellulose (CMC) containing cisplatin, and chemotherapeutic activity was rendered to two types of granules via adsorption. Then, mechanical properties, porosity, morphology, drug release kinetics, ex vivo reconstructive properties of porous PMMA and in vitro anti-cancer efficacy against osteosarcoma cells were assessed. Morphologies, molecular structures, drug release profiles and in vitro cytostatic effects of two different drug-loaded granules on the proliferation of metastatic bone tumor cells were investigated. The mechanical strengths of PMMA-based cements were sufficient for tibia reconstruction at CMC contents lower than 4% (≤3%). The concentrations of released cisplatin (12.1% and 16.6% from PMMA with 3% and 4% CMC, respectively) were sufficient for killing of osteosarcoma cells, and the fraction of dead cells increased to 91.3% within 7 days. Functionalized xenogeneic granules released 29.5% of cisplatin, but synthetic CaP granules only released 1.4% of cisplatin over 28 days. The immobilized and released cisplatin retained its anti-cancer efficacy and showed dose-dependent cytostatic effects on the viability of metastatic bone tumor cells. Bone substitutes can be rendered therapeutically active for anticancer efficacy by functionalization with cisplatin. As such, our data suggest that multi-functional PMMA-based cements and cisplatin-loaded granules represent viable treatment options for filling bone defects after bone tumor resection

In chronically infected fracture non-unions, treatment requires extensive debridement to remove necrotic and infected bone, often resulting in large defects requiring elaborate and prolonged bone reconstruction. One approach includes the induced membrane technique (IMT), although the differences in outcome between infected and non-infectious aetiologies remain unclear. Here we present a new rabbit humerus model for IMT secondary to infection, and, furthermore, we compare bone healing in rabbits with a chronically infected non-union compared to non-infected equivalents. A 5 mm defect was created in the humerus and filled with a polymethylmethacrylate (PMMA) spacer or left empty (n=6 per group). After 3 weeks, the PMMA spacer was replaced with a beta-tricalcium phosphate (chronOs, Synthes) scaffold, which was placed within the induced membrane and observed for a further 10 weeks. The same protocol was followed for the infected group, except that four week prior to treatment, the wound was inoculated with Staphylococcus aureus (4×10. 6. CFU/animal) and the PMMA spacer was loaded with gentamicin, and systemic therapy was applied for 4 weeks prior to chronOs application. All the animals from the infected group were culture positive during the first revision surgery (mean 3×10. 5. CFU/animal, n= 12), while at the second revision, after antibiotic therapy, all the animals were culture negative. The differences in bone healing between the non-infected and infected groups were evaluated by radiography and histology. The initially infected animals showed impaired bone healing at euthanasia, and some remnants of bacteria in histology. The non-infected animals reached bone bridging in both empty and chronOs conditions. We developed a preclinical in vivo model to investigate how bacterial infection influence bone healing in large defects with the future aim to explore new treatment concepts of infected non-union

Abstract. Objectives. The principle of osteoporotic vertebral compression fracture (OVCF) is fixing instability, providing anterior support, and decompression. Contraindication for vertebroplasty is anterior or posterior wall fracture. The study objectives was to evaluate the efficacy and safety of vertebroplasty with short segmented PMMA cement augmented pedicle screws for OVCF with posterior/anterior wall fracture patients. Methods. A retrospective study of 24 patients of DGOU type-4 (vertebra plana) OVCF with posterior/anterior wall fracture, were treated by vertebroplasty and short segment PMMA cement augmented pedicle screws fixation. Radiological parameters (kyphosis angle and compression ratio) and clinical parameters Visual analogue scale (VAS) and Oswestry disability index (ODI) were analysed. Results. A significant improvement was noted in VAS (preoperative, 7.90 ±0.60; final follow-up 2.90 ± 0.54) and ODI (77.10 ± 6.96 to 21.30 ± 6.70), (P < 0.05). Neurological improvement was noted in all patients. Kyphosis corrected significantly from preoperative 23.20±5.90 to 5.30±1.40 postoperative with 5% (3.30± 2.95) loss of correction at final follow-up. Anterior vertebral height restored significantly from 55.80±11.9% t0 87.6±13.1% postoperative with 4.5±4.0% loss at final follow-up. One case had cement leakage was found, but the patient is asymptomatic. No implant-related complication was seen. No iatrogenic dural or nerve injury. Conclusions. Treatment with vertebroplasty with cement augmented screw fixation and direct decompression is a great option in treating such a complex situation in fragile age with fragile bones because It provides anterior support with cementing that avoids corpectomy. Short segment fixation has less stress risers at the junctional area

A spine compression fracture is a very common form of fracture in elderly with osteoporosis. Injection of polymethyl methacrylate (PMMA) to fracture sites is a minimally invasive surgical treatment, but PMMA has considerable clinical risks. We develop a novel type thermoplastic injectable bone substitute contains the proprietary composites of synthetic ceramic bone substitute and absorbable thermoplastic polymer. We used thermoplastic biocompatible polymers Polycaproactone (PCL) to encapsulate calcium-based bone substitutes hydroxyapatite (Ca10(PO4)6(OH)2, HA) and tricalcium phosphate (TCP) to form a biodegradable injectable bone composite material. The space occupation ration PCL:HA/TCP is 1:9. After heating process, it can be injected to fracture site by specific instrument and then self-setting to immediate reinforce the vertebral body. The thermoplastic injection bone substitute can obtain good injection properties after being heated by a heater at 90˚C for three minutes, and has good anti-washout property when injected into normal saline at 37˚C. After three minutes, solidification is achieved. Mechanical properties were assessed using the material compression test system and the mechanical support close to the vertebral spongy bone. In vitro cytotoxicity MTT assay (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was performed and no cell cytotoxicity was observed. In vivo study with three New Zealand rabbits was performed, well bone growth into bone substitute was observed and can maintain good mechanical support after three months implantation. The novel type thermoplastic injection bone substitute can achieve (a) adequate injectability and viscosity without the risk of cement leakage; (b) adequate mechanical strength for immediate reinforcement and prevent adjacent fracture; (c) adequate porosity for new bone ingrowth; (e) biodegradability. It could be developed as a new option for treating vertebral compression fractures

Majority of osteoporosis related fractures are treated surgically using metallic fixation devices. Anchorage of fixation devices is sometimes challenging due to poor osteoporotic bone quality that can lead to failure of the fracture fixation. Using a rat osteoporosis model, we employed neutron tomography and histology to study the biological effects of implant augmentation using an isothermally setting calcium sulphate/hydroxyapatite (CaS/HA) biomaterial with synthetic HA particles as recruiting moiety for systemically administered bisphosphonates. Using an osteoporotic sawbones model, we then provide a standardized method for the delivery of the CaS/HA biomaterial at the bone-implant interface for improved mechanical anchorage of a lag-screw commonly used for hip fracture fixation. As a proof-of-concept, the method was then verified in donated femoral heads and in patients with osteoporosis undergoing hip fracture fixation. We show that placing HA particles around a stainless-steel screw in-vivo, systemically administered bisphosphonates could be targeted towards the implant, yielding significantly higher peri-implant bone formation compared to un-augmented controls. In the sawbones model, CaS/HA based lag-screw augmentation led to significant increase (up to 4 times) in peak extraction force with CaS/HA performing at par with PMMA. Micro-CT imaging of the CaS/HA augmented lag-screws in cadaver femoral heads verified that the entire length of the lag-screw threads and the surrounding bone was covered with the CaS/HA material. X-ray images from fracture fixation surgery indicated that the CaS/HA material could be applied at the lag-screw-bone interface without exerting any additional pressure or risk of venous vascular leakage.: We present a new method for augmentation of lag-screws in fragile bone. It is envisaged that this methodcould potentially reduce the risk of fracture fixation failure especially when HA seeking “bone active” drugs are used systemically

The enhancement of current bone cement properties is a challenging issue that has been the focus of much research. Developing bone composites with high level of cytocompatibility, mechanical and antibacterial properties is a challenging task. We overcome this challenge by designing a nanocomposite that contain two-dimensional (2D) nanosheets. To develop our novel bone cement nanocomposite, 2D nanosheets were synthesized, mixed in different ratios, and then added to the PMMA matrix. The results reveal that the incorporation of 2D nanosheets into the PMMA matrix leads to increase in the antibacterial properties of the bone cement composite against E. coli bacteria. In addition, the 2D nanosheets improve the compression strength of the bone cement nanocomposite significantly. We also show that nanosheets increased the bioactivity of the bone cements. Finally, MTT assay results indicate that PMMA as a control sample has the lowest cytocompatibility, however, our novel nanocomposites have the highest amount of cytocompatibility. Thus, the current study suggests that 2D nanosheets are potential filler components for the next generation of PMMA bone cement nanocomposites. The findings of this work reveal that the excellent performance of the proposed bone composite can result in a paradigm shift in design of state-of-the art bone cement composites

Abstract. Objectives. While spinal fusion is known to be associated with adjacent disc degeneration, little is known on the role of the facet joints in the process, and whether their altered biomechanics following fusion plays a role in further spinal degeneration. This work aimed to develop a model and method to sequentially measure the effects of spinal fusion on lumbar facet joints through synchronisation of both motion analysis, pressure mapping and mechanical analysis. Methods. Parallel measurements of mature ovine lumbar facet joints (∼8yr old, n=3) were carried out using synchronised load and displacement measurements, motion capture during loading and pressure mapping of the joint spaces during loading. Functional units were prepared and cemented in PMMA endcaps. Displacement-controlled compression measurements were carried out using a materials testing machine (3365, Instron, USA) at 1 mm/min up to 950 N with the samples in a neutral position, while motion capture of the facet joints during compression was carried out using orthogonal HD webcams (Logitech, Switzerland) to measure the displacement of key facet joint features. The pressure mapping of load transfer during displacement was carried out using a flexible pressure sensor (6900 series, Tekscan, USA). Each sample was imaged at an isotropic resolution of 82 microns using a μCT scanner (XtremeCT, Scanco, Switzerland) to quantify the curvature within the facet joints. Results. Relative facet joint displacement under load, in a neutral position, showed more displacement (2.36 ±1.68 mm) compared to the cross-head when under compression (2.06 ±1.19 mm). Motion capture indicated the relative displacement of the facet joints was more posterior with some lateral motion. For five of the six facet joints, pressure measurement was possible only on 24±7 % of the surface due to the large change in curvature. Partially measured loads through the facets was 10.5 ±1.1 N. Conclusions. The relative displacement of the lumbar facet joints compared to the crosshead displacement was consistent with previous studies of cervical facet joints, despite the differences in anatomical geometry between cervical and lumbar joints. The difficulties in accurately measuring the load transfer through the facet joints was due to the age of the tissue and the degree of curvature of the facet joints. Synchronisation of the biomechanical data will provide a setup to assess the effect of interventions such as spinal fusion, with curvature-related issues unlikely to occur in human spines. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Spinal surgery deals with the treatment of different pathological conditions of the spine such as tumors, deformities, degenerative disease, infections and traumas. Research in the field of vertebral surgery can be divided into two main areas: 1) research lines transversal to the different branches; 2) specific research lines for the different branches. The transversal lines of research are represented by strategies for the reduction of complications, by the development of minimally invasive surgical techniques, by the development of surgical navigation systems and by the development of increasingly reliable systems for the control of intra-operative monitoring. Instead, specific lines of research are developed within the different branches. In the field of oncological pathology, the current research concerns the development of in vitro models for the study of metastases and research for the study of targeted treatment methods such as electrochemotherapy and mesenchymal stem cells for the treatment of aneurysmal bone cysts. Research in the field of spinal deformities is focused on the development of increasingly minimally invasive methods and systems which, combined with appropriate pharmacological treatments, help reduce trauma, stress and post-operative pain. Scaffolds based on blood clots are also being developed to promote vertebral fusion, a fundamental requirement for improving the outcome of vertebral arthrodesis performed for the treatment of degenerative disc disease. To improve the management and the medical and surgical treatment of vertebral infections, research has focused on the definition of multidisciplinary strategies aimed at identifying the best possible treatment path. Thus, flow-charts have been created which allow to manage the patient suffering from vertebral infection. In addition, dedicated silver-coated surgical instrumentation and bone substitutes have been developed that simultaneously guarantee mechanical stability and reduce the risk of further local infection. In the field of vertebral traumatology, the most recent research studies have focused on the development of methods for the biostimulation of the bone growth in order to obtain, when possible, healing without surgery. Methods have also been developed that allow the minimally invasive percutaneous treatment of fractures by means of vertebral augmentation with PMMA, or more recently with the use of silicone which from a biomechanical point of view has an elastic modulus more similar to that of bone. It is clear that scientific research has changed clinical practice both in terms of medical and surgical management of patients with spinal pathologies. The results obtained stimulate the basic research to achieve even more. For this reason, new lines of research have been undertaken which, in the oncology field, aim at developing increasingly specific therapies against target receptors. Research efforts are also being multiplied to achieve regeneration of the degenerated intervertebral disc and to develop implants with characteristics increasingly similar to those of bone in order to improve mechanical stability and durability over time. Photodynamic therapies are being developed for the treatment of infections in order to reduce the use of antibiotic therapies. Finally, innovative lines of research are being launched to treat and regenerate damaged nerve structures with the goal, still far from today, of making patients with spinal cord injuries to walk

Intro. Calcium sulphate (CS) is a recent alternative for antibiotic elution in infected bones and joints. The purpose of this study is to evaluate the use of antibiotic impregnated calcium sulphate (AICS) beads in the management of infected tibia and femur, with regards to patient outcomes and complication rates (including reinfection rate, remission rate and union rate). Methods. Searches of AMED, CINAHL, EMBASE, EMCARE, Medline, PubMed and Google Scholar were conducted in June 2020, with the mesh terms: “Calcium sulphate beads” or “Calcium sulfate beads” or “antibiotic beads” or “Stimulan” AND “Bone infection” or “Osteomyelitis” or “Debridement” AND “Tibia” or “Femur”. Risk of bias was assessed using the Risk of Bias in Non-randomised Studies of interventions (ROBINS-i) tool, and quality assessed via the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria. Results. Out of 105 relevant papers, 11 met the inclusion criteria for data extraction. Total infection recurrence rate was 6.8% (range 3.2 – 11.9%, n = 295), which was significantly lower (p < 0.001) than that of polymethylmethacrylate (PMMA; 19.6%, n = 163). Complication rates varied. The main issue regarding AICS use was wound drainage (7.9 – 33.3%), which was considerably higher in studies involving treatment of the tibia only. Studies using PMMA did not experience this issue, but there were a few incidences of superficial pin tract infection following surgery. Conclusions. AICS was consistently effective at infection eradication, despite variation in causative organism and location of bead placement. Additionally, PMMA has many inconvenient properties. AICS is therefore an attractive alternative as an adjunct in treatment of infected tibia and femur. Wound drainage rate varied and was higher in studies regarding tibial cases alone

Objectives. Third-body wear is believed to be one trigger for adverse results with metal-on-metal (MOM) bearings. Impingement and subluxation may release metal particles from MOM replacements. We therefore challenged MOM bearings with relevant debris types of cobalt–chrome alloy (CoCr), titanium alloy (Ti6Al4V) and polymethylmethacrylate bone cement (PMMA). Methods. Cement flakes (PMMA), CoCr and Ti6Al4V particles (size range 5 µm to 400 µm) were run in a MOM wear simulation. Debris allotments (5 mg) were inserted at ten intervals during the five million cycle (5 Mc) test. . Results. In a clean test phase (0 Mc to 0.8 Mc), lubricants retained their yellow colour. Addition of metal particles at 0.8 Mc turned lubricants black within the first hour of the test and remained so for the duration, while PMMA particles did not change the colour of the lubricant. Rates of wear with PMMA, CoCr and Ti6Al4V debris averaged 0.3 mm. 3. /Mc, 4.1Â mm. 3. /Mc and 6.4 mm. 3. /Mc, respectively. . Conclusions. Metal particles turned simulator lubricants black with rates of wear of MOM bearings an order of magnitude higher than with control PMMA particles. This appeared to model the findings of black, periarticular joint tissues and high CoCr wear in failed MOM replacements. The amount of wear debris produced during a 500 000-cycle interval of gait was 30 to 50 times greater than the weight of triggering particle allotment, indicating that MOM bearings were extremely sensitive to third-body wear. Cite this article: Bone Joint Res 2015;4:29–37

Abstract. Objective. Open fracture management in the United Kingdom and several other countries is guided by the British Orthopaedic Association's Standards for Trauma Number 4 (BOAST-4). This is updated periodically and is based on the best available evidence at the time. The aim of this study is to evaluate the evidence base forming this guidance and to highlight new developments since the last version in 2017. Methods. Searches have been performed using the PubMed, Embase and Medline databases for time periods a) before December 31, 2017 and from 01/01/2018–01/02/2021. Results have been summarised and discussed. Results. Several contentious issues remain within the 2017 guideline. Antibiotic guidance, the use of antibiotic impregnated PMMA beads and intramedullary devices, irrigation in the emergency department, time to theatre and the use of negative pressure dressings and guidance regarding the management of paediatric injuries have all demonstrated no clear consensus. Conclusion. The advent of the BOAST-4 guideline has been of huge benefit, however the refinement and improvement of this work remains ongoing. There remains a need for further study into these contentious issues previously listed

Introduction. Polymethylmethacrylate(PMMA) bone cement has been used in joint reconstruction surgery and recently introduced for treatment of osteoporotic vertebral compression fracture. However, the use of PMMA bone cement in vertebroplasty leads to extensive bone stiffening and high rate of adjacent vertebrae fracture. Aim. The purpose of this study was to investigate the properties of PMMA bone cement augmented with collagen and assess its characteristics and relevance for the reduction of complication rate associated with vertebroplasty. Methods. Bone cement was produced using 2 types of PMMA based bone cement. Augmented groups were prepared using 40g of bone cement with 1% of rat tail liquid collagen. Mixing was conducted in controlled laboratory environment and at room temperature. The working and setting time and the mechanical properties were determined in accordance to ASTM standards for acrylic cements. The effect of ageing in simulated body fluid(SBF) on mechanical properties of these cements and the microstructure were studied. Results. Addition of collagen to bone cement has shown no marked effect on the working and setting time and produces bone cement with good injectability. The compressive strength is not affected but the modulus shows the material is less brittle than PMMA. Conclusion. Addition of liquid collagen to PMMA based bone cement does not necessarily compromise the properties of the cements and produce cement with good injectability and less brittle than PMMA based bone cement alone. However, bone cement augmented with different concentration of collagen need to be studied further in order to assess its clinical relevance especially in vertebroplasty

Abstract. Objectives. To evaluate the safety and efficacy of vertebroplasty with short segmented cement augmented pedicle screws fixation for severe osteoporotic vertebral compression fractures (OVCF) with posterior/anterior wall fractured patients. Methods. A retrospective study of 24 patients of DGOU type-4 (vertebra plana) OVCF with posterior/anterior wall fracture, were treated by vertebroplasty and short segment PMMA cement augmented pedicle screws fixation. Radiological parameters (kyphosis angle and compression ratio) and clinical parameters Visual analogue scale (VAS) and Oswestry disability index (ODI) were analysed. Results. A significant improvement was noted in VAS (preoperative, 7.90 ± 0.60; final follow-up 2.90 ± 0.54) and ODI (77.10 ± 6.96 to 21.30 ± 6.70), (P < 0.05). Neurological improvement was noted in all patients. Kyphosis corrected significantly from preoperative 23.20 ± 5.90 to 5.30 ± 1.40 postoperative with 5% (3.30 ± 2.95) loss of correction at final follow-up. Anterior vertebral height restored significantly from 55.80 ± 11.9% to 87.6 ± 13.1% postoperative with 4.5 ± 4.0% loss at final follow-up. One case had cement leakage was found, but the patient is asymptomatic. No implant-related complication was seen. No iatrogenic dural or nerve injury. Conclusions. Treatment with vertebroplasty with cement augmented screw fixation and direct decompression is a great option in treating such a complex situation in fragile age with fragile bones because. Vertebroplasty is viable option for restoring vertebral anterior column in patients who are considered as contraindications for vertebroplasty, like DGOU-4. It provides anterior support avoiding corpectomy, minimise blood loss and also duration of surgery. Addition of short segment fixation gives adequate support with less stress risers at the junctional area

Proponents of the biological theory of aseptic loosening have in recent years tended to concentrate on the production and distribution of particulate ultra-high-molecular-weight polyethylene (UHMWPE) debris around the potential joint space. However, mechanical loading of cemented implants with the differing elastic moduli of metal stems, polymethylmethacrylate (PMMA) cement and bone can result in relative micromotion, implying the potential for production of metal and PMMA particles from the stem-cement interface by fretting wear. In order to investigate the production and biological reactivity of debris from this interface, PMMA and metal particulate debris was produced by sliding wear of PMMA pins containing barium sulphate and zirconium dioxide against a Vaquasheened stainless steel counterface. This debris was characterised by SEM, energy-dispersive analysis by X-ray (EDAX) and image analysis, then added to cell cultures of a human monocytic cell line, U937, and stimulation of pro-osteolytic cytokines measured by ELISA. Large quantities of PMMA cement debris were generated by the sliding wear of PMMA pins against Vaquasheened stainless steel plates in the method developed for this study. Both cements stimulated the release of pro-osteolytic TNFα from the U937 monocytic cell line, in a dose-dependent fashion. There was a trend towards greater TNFα release with Palacos cement than CMW cement at the same dose. Palacos particles also caused significant release of IL-6, another pro-osteolytic cytokine, while CMW did not. The particulate cement debris produced did not stimulate the release of GM-CSF or IL1β from the U937 cells. These results may explain the cytokine pathway responsible for bone resorption caused by particulate PMMA debris. Radio-opaque additives are of value in surgical practice and clinical studies to quantify the relevance of these in vitro findings are required before the use of cement containing radio-opacifier is constrained

Interbody fusion aims to treat painful disc disease by demobilising the spinal segment through the use of an interbody fusion device (IFD). Diminished contact area at the endplate interface raises the risk of device subsidence, particularly in osteoporosis patients. The aim of the study was to ascertain whether vertebral body (VB) cement augmentation would reduce IFD subsidence following dynamic loading. Twenty-four human two-vertebra motion segments (T6–T11) were implanted with an IFD and distributed into three groups; a control with no cement augmentation; a second with PMMA augmentation; and a third group with calcium phosphate (CP) cement augmentation. Dynamic cyclic compression was applied at 1Hz for 24 hours in a specimen specific manner. Subsidence magnitude was calculated from pre and post-test micro-CT scans. The inferior VB analysis showed significantly increased subsidence in the control group (5.0±3.7mm) over both PMMA (1.6±1.5mm, p=.034) and CP (1.0±1.1mm, p=.010) cohorts. Subsidence in the superior VB to the index level showed no significant differences (control 1.6±3.0mm, PMMA 2.1±1.5mm, CP 2.2±1.2mm, p=.811). In the control group, the majority of subsidence occurred in the lower VB with the upper VB displaying little or no subsidence, which reflects the weaker nature of the superior endplate. Subsidence was significantly reduced in the lower VB when both levels were reinforced regardless of cement type. Both PMMA and CP cement augmentation significantly affected IFD subsidence by increasing VB strength within the motion segment, indicating that this may be a useful method for widening indications for surgical interventions in osteoporotic patients

Introduction and Objective. The continued effectiveness of antibiotic loaded bone cements is threatened by antibiotic resistance. The common antiseptic, chlorhexidine (CHX), is a potential alternative to antibiotics in bone cements, but conventional salts are highly soluble, causing burst release and rapid decline to subinhibitory local CHX concentrations. Here, chlorhexidine triphosphate (CHX-TP), a low solubility CHX salt, is investigated as an alternative antimicrobial in PMMA bone cements. The aim was to assess duration of antimicrobial release and antimicrobial efficacy, along with handling, setting and mechanical properties of CHX-TP loaded cements, compared with an existing cement formulation containing gentamicin. Materials and Methods. Palacos R (Heraeus Medical, Newbury, UK) with 0, 1, 4, 7 and 12% CHX-TP (w/w) cements were prepared by combining solid CHX-TP with Palacos R components, and compared with Palacos R+G. All cements were prepared without vacuum and under ISO 5833:2002 conditions. Cements were tested under ISO 5833:2002 for compressive and bending properties, setting time, maximum temperature and doughing time. Antimicrobial release from the cements into deionised water was studied and antimicrobial efficacy of unaged and aged cements against Staphylococcus aureus (ATCC 29213) was assessed using a disc diffusion assay. Results. Compressive strength of CHX-TP loaded cements was not significantly different to Palacos R or Palacos R+G (p > 0.05, all exceeding ISO 5833:2002 minimum of 70 MPa). Mean bending strength was significantly lower with CHX-TP loading (p < 0.05) than bending strength of Palacos R and Palacos R+G, though all bending moduli exceeded the ISO 5833:2002 minimum (1800 MPa). All cements studied were within the ISO 5833:2002 limits for setting time (3 to 15 min), doughing time (≤ 5 min) and maximum temperature (90 . o. C). Mean doughing time for Palacos R, Palacos R+G and Palacos R + 12 % CHX-TP respectively: 52.5 s, 45 s and 45 s. Mean setting time and mean maximum temperature for Palacos R, Palacos R+G and Palacos R + 1, 4, 7 and 12% CHX-TP respectively: 11.00 min (73 . o. C), 11.25 min (72 . o. C), 12.25 min (66 . o. C), 10.50 min (70 . o. C), 10.00 min (70 . o. C), 10.75 min (62 . o. C). Sustained CHX release into deionised water was observed from all Palacos R + CHX-TP cements. Duration varied according to CHX-TP dosing and diminished over time, although to an extent that itself varied with dosing. 1 % CHX-TP ceased releasing CHX at 6.9 weeks; 4 % CHX-TP ceased at 67.7 weeks; 7 % and 12 % CHX-TP were ongoing at 75.5 weeks. Palacos R+G cements ceased releasing detectable levels of gentamicin after 14.4 weeks. Palacos R+G and Palacos R + CHX-TP cement discs showed efficacy against S. aureus (ATCC 29213) when applied as prepared (unaged) to S. aureus bacterial lawns in disc diffusion assays, with CHX-TP cements showing dose dependency. Zone of inhibition (ZOI) size was significantly reduced for Palacos R+G cements and Palacos R + 1% CHX-TP cements after 1 week and 6 weeks aging, compared to ZOI from unaged cements (p < 0.05). ZOI size produced by Palacos R + 4, 7, and 12 % CHX-TP cements did not decline significantly after 6 weeks aging (p > 0.05). Conclusions. CHX-TP can be incorporated into the Palacos R cement matrix up to 12% w/w without deterioration of compressive strength, bending modulus, doughing time, setting time or maximum temperature. Bending strength was significantly reduced at all CHX-TP loadings studied. Palacos R + 4, 7 and 12% CHX-TP cements provided sustained CHX release, exceeding the duration of gentamicin release from Palacos R+G, and showed sustained efficacy against S. Aureus after 6 weeks aging, which was not achieved by Palacos R+G cements