Effects of long-term strontium ranelate treatment on the risk of nonvertebral and vertebral fractures in postmenopausal osteoporosis: Results of a five-year, randomized, placebo-controlled trial

Antimicrobial Properties of Strontium Functionalized Titanium Surfaces for Oral Applications, A Systematic Review

The aim of this systematic review was to assess the current scientific evidence of the antimicrobial potential of strontium (Sr) when used to functionalize titanium (Ti) for oral applications. Out of an initial list of 1081 potentially relevant publications identified in three electronic databases (MEDLINE via PubMed, Scopus, and Cochrane) up to 1 February 2021, nine publications based on in vitro studies met the inclusion criteria. The antimicrobial potential of Sr was investigated on different types of functionalized Ti substrates, employing different application methods. Nine studies reported on the early, i.e., 6–24 h, and two studies on the late, i.e., 7–28 days, antimicrobial effect of Sr, primarily against Staphylococcus aureus (S. aureus) and/or Escherichia coli (E. coli). Sr-modified samples demonstrated relevant early antimicrobial potential against S. aureus in three studies; only one of which presented statistical significance values, while the other two presented only the percentage of antimicrobial rate and biofilm inhibition. A relevant late biofilm inhibition potential against S. aureus of 40% and 10%—after 7 and 14 days, respectively—was reported in one study. Combining Sr with other metal ions, i.e., silver (Ag), zinc (Zn), and fluorine (F), demonstrated a significant antimicrobial effect and biofilm inhibition against both S. aureus and E. coli. Sr ion release within the first 24 h was generally low, i.e., below 50 µg/L and 0.6 ppm; however, sustained Sr ion release for up to 30 days, while maintaining up to 90% of its original content, was also demonstrated. Thus, in most studies included herein, Sr-functionalized Ti showed a limited immediate (i.e., 24 h) antimicrobial effect, likely due to a low Sr ion release; however, with an adequate Sr ion release, a relevant antimicrobial effect, as well as a biofilm inhibition potential against S. aureus—but not E. coli—was observed at both early and late timepoints. Future studies should assess the antimicrobial potential of Ti functionalized with Sr against multispecies biofilms associated with peri-implantitis.

Effects of strontium ions with potential antibacterial activity on in vivo bone regeneration

Bioactive glasses (BGs) have attracted added attention in the structure of the scaffolds for bone repair applications. Different metal ions could be doped in BGs to induce specific biological responses. Among these ions, strontium (Sr) is considered as an effective and safe doping element with promising effects on bone formation and regeneration. In this experiment, we evaluated the antibacterial activities of the gelatin-BG (Gel-BG) and Gel-BG/Sr scaffolds in vitro. The osteogenic properties of the prepared scaffolds were also assessed in rabbit calvarial bone defects for 12 weeks. Both scaffolds showed in vivo bone formation during 12 weeks with the newly formed bone area in Gel-BG/Sr scaffold was higher than that in Gel-BG scaffolds after the whole period. Based on the histological results, Gel-BG/Sr exhibited acceleration of early-stage bone formation in vivo. The results of antibacterial investigation for both scaffolds showed complete growth inhibition against Escherichia coli (E. coli). Although Gel-BG revealed no antibacterial effect on Staphylococcus aureus (S. aureus), the Gel-BG/Sr was able to partially inhibit the growth of S. aureus, as detected by threefold reduction in growth index. Our results confirmed that Sr doped BG is a favorable candidate for bone tissue engineering with superior antibacterial activity and bone regeneration capacity compared with similar counterparts having no Sr ion.

Effect of Strontium Ranelate on Condylar Growth during Mandibular Advancement in Rats

Objective

Strontium ranelate (SR), unlike other anti-osteoporotic agents, might not only prevent bone resorption but also might induce bone formation. The aim of this experimental study was to evaluate the effects of systemic SR on condylar growth during mandibular advancement (MA) in growing rats.

Methods

Fifty-six, 8-week-old Wistar male rats weighting 160-190 g were randomly divided into four groups; one control (n=14) and three experimental (n=14). Group 1: Control group, Group 2: SR (900mg/kg daily dose), Group 3: MA, Group 4: SR +MA. The amount and direction of mandibular growth were assessed by linear measurements on the computed tomography (CT) images taken on days 1, 15, and 30. For immunohistochemical evaluation, half of the subjects in the groups were sacrificed on the 15th day (early phase) and the rest of them on the 30th day (late phase). New cartilage and bone formation areas on the condyle were analyzed by using Sox9 and Osteopontin antibodies.

Results

Early and late CT images measurements showed no significant difference between the groups (p<0.05). However, there were significant differences between the control and experimental groups in the immunohistochemical assessment. Severe immunolocalization of SOX9 and Osteopontin was observed in Group 4, while the immunolocalization scores were moderate in Group 2 and Group 3. In addition, early histological findings were similar to late results in all groups.

Conclusion

In mandibular advancement therapy, Strontium ranelate could be therapeutically effective in avoiding relapse and reducing the duration of retention.

Comparable Effects of Strontium Ranelate and Alendronate Treatment on Fracture Reduction in a Mouse Model of Osteogenesis Imperfecta

Alendronate (Aln) has been the first-line drug for osteogenesis imperfecta (OI), while the comparable efficacy of Aln and strontium ranelate (SrR) remains unclear. This study is aimed at comparing the effects of SrR and Aln treatment in a mouse model of OI. Three-week-old oim/oim and wt/wt female mice were treated with SrR (1800 mg/kg/day), Aln (0.21 mg/kg/week), or vehicle (Veh) for 11 weeks. After the treatment, the average number of fractures sustained per mouse was significantly reduced in both SrR- and Aln-treated oim/oim mice. The effect was comparable between these two agents. Both SrR and Aln significantly increased trabecular bone mineral density, bone histomorphometric parameters (bone volume, trabecular number, and cortical thickness and area), and biomechanical parameters (maximum load and stiffness) as compared with the Veh group. Both treatments reduced bone resorption parameters, with Aln demonstrating a stronger inhibitory effect than SrR. In contrast to its inhibitory effect on bone resorption, SrR maintained bone formation. Aln, however, also suppressed bone formation coupled with an inhibitory effect on bone resorption. The results of this study indicate that SrR has comparable effects with Aln on reducing fractures and improving bone mass and strength. In clinical practice, SrR may be considered an option for patients with OI when other medications are not suitable or have evident contraindications.

Pharmacological Management of Postmenopausal Osteoporosis: a Level I Evidence Based - Expert Opinion

Objectives: Postmenopausal osteoporosis carries a high risk of fractures, which decrease quality of life and are associated with high morbidity, mortality, and economic burden. The best pharmacological treatment options to manage and prevent osteoporotic fractures remain still unclear. The present study investigated the efficacy and safety of the most commonly employed drugs in the management of postmenopausal osteoporosis. Methods: Only RCTs comparing different drugs for the management of postmenopausal osteoporosis were included. Data from 76 RCTs (205,011 patients) were collected. The mean follow-up was 27.6 ± 14.9 months. Results: Denosumab reported the lowest rate of non-vertebral fractures (LOR -1.57), Romosozumab the lowest rate of vertebral fractures (LOR 1.99), and Ibandronate the lowest rate of hip fractures (LOR0.18). Serious adverse events resulted in the lowest in the Raloxifene group (LOR 3.11), while those leading to study discontinuation were lowest in the Romosozumab cohort (LOR 2.65). Conclusions: Denosumab resulted in most effective, particularly in reducing the occurrence of non-vertebral fractures. Romosozumab and Ibandronate resulted best to prevent, respectively, vertebral fractures and hip fractures. Adverse events leading to study discontinuation were less frequent in the Romosozumab and Denosumab groups, while Raloxifene and Alendronate showed a lower incidence of serious adverse events overall. Level of evidence: I, Bayesian network meta-analysis of RCTs.

Strontium ranelate-loaded POFC/β-TCP porous scaffolds for osteoporotic bone repair

It is of considerable significance to fabricate scaffolds with satisfactory osteogenic activities and high osteogenesis quality to accelerate osteoporotic repair. In this study, we initially fabricated the POFC/β-TCP porous scaffold in the light of composition and structure bionics, and then loaded the SR to the optimized POFC/β-TCP porous scaffold by 3D printing based on FFS-MDJ. The hydrophilicity, mechanical properties biodegradability and cell response of the composite scaffolds were systematically investigated. The result showed that modified POFC enhanced the hydrophilicity and ameliorated the brittleness of pure β-TCP. β-TCP buffered the acidity and improved the degradability and cell affinity of the scaffold, and the release of strontium ranelate significantly promote the proliferation and differentiation of osteoblasts and guided bone regeneration. The results indicated that POFC/β-TCP scaffolds had uniform macropores of 300–500 μm and a porosity of approximately 48%, adjustable biodegradability and a high compressive modulus of 30–60 MPa. The strontium ranelate-loaded POFC/β-TCP scaffold enhanced the osteogenic differentiation of rBMSCs, which might be a promising candidate for osteoporotic-related bone defect repair.

It is of considerable significance to fabricate scaffolds with satisfactory osteogenic activities and high osteogenesis quality to accelerate osteoporotic repair.

A bioceramic scaffold composed of strontium-doped three-dimensional hydroxyapatite whiskers for enhanced bone regeneration in osteoporotic defects

Reconstruction of osteoporotic bone defects is a clinical problem that continues to inspire the design of new materials. Methods: In this work, bioceramics composed of strontium (Sr)-doped hydroxyapatite (HA) whiskers or pure HA whiskers were successfully fabricated by hydrothermal treatment and respectively named SrWCP and WCP. Both bioceramics had similar three-dimensional (3D) porous structures and mechanical strengths, but the SrWCP bioceramic was capable of releasing Sr under physiological conditions. In an osteoporotic rat metaphyseal femoral bone defect model, both bioceramic scaffolds were implanted, and another group that received WCP plus strontium ranelate drug administration (Sr-Ran+WCP) was studied for comparison. Results: At week 1 post-implantation, osteogenesis coupled blood vessels were found to be more common in the SrWCP and Sr-Ran+WCP groups, with substantial vascular-like structures. After 12 weeks of implantation, comparable to the Sr-Ran+WCP group, the SrWCP group showed induction of more new bone formation within the defect as well as at the implant-bone gap region than that of the WCP group. Both the SrWCP and Sr-Ran+WCP groups yielded a beneficial effect on the surrounding trabecular bone microstructure to resist osteoporosis-induced progressive bone loss. While an abnormally high blood Sr ion concentration was found in the Sr-Ran+WCP group, SrWCP showed little adverse effect. Conclusion: Our results collectively suggest that the SrWCP bioceramic can be a safe bone substitute for the treatment of osteoporotic bone defects, as it promotes local bone regeneration and implant osseointegration to a level that strontium ranelate can achieve.

Therapeutic Effect of Strontium Ranelate on Bone in Chemotherapy-Induced Osteopenic Rats via Increased Bone Volume and Reduced Bone Loss

The purpose of this study was to determine whether treatment with strontium ranelate (SrR) can restore bone mass and strength at a skeletal site with established osteopenia in chemotherapy-induced rats. Forty-five Sprague-Dawley male rats were randomly assigned to three study groups (n = 15 rats per group): normal rats (control group), osteopenic rats (chemo group), and osteopenic rats with SrR (chemo-SrR group). We chose a male rat model that mimicked a clinical setting by weekly intravenous injection of cyclophosphamide at 20 mg/kg. The control and chemo groups were maintained without treatment, and the chemo-SrR group was intragastrically administered strontium ranelate at a dosage of 900 mg/kg/day. All animals were fed a standard laboratory diet, and blood samples were collected for biochemical analysis. After 12 weeks of treatment, micro-CT, biomechanical testing, and histomorphometry were examined. In addition, bone samples were obtained to evaluate the content of mineral substances in bones. SrR treatment of chemo rats significantly increased tibial trabecular bone volume, trabecular thickness, and BV/TV. Serum levels of the bone formation marker alkaline phosphatase (ALP) in the SrR group were significantly higher than those in the chemo animals, which was accompanied by an increase in the bone mineral content, bone calcium and phosphate, as well as reduced serum Ca and P concentrations. The serum level of tartrate-resistant acid phosphatase (TRAP) in the SrR treatment group showed no obvious changes. Histomorphological analyses revealed that chemotherapy resulted in decreased osteoclast number, which may be due to the inhibition of bone turnover. However, SrR treatment enhanced the number of osteoblasts while restoring bone mass and improving bone strength in chemo rats. Therefore, the results of this study indicate that SrR treatment has a positive effect on bone in chemotherapy-induced osteoporosis.

Impact of bisphosphonate compliance on the risk of osteoporotic fracture in France

Limited information is available on the impact of bisphosphonate compliance levels on fracture risk in osteoporosis patients in France. The results of this nested case-control, retrospective study suggest that fracture risk did not significantly change with bisphosphonate compliance levels, except for highly compliant patients.

PURPOSE/INTRODUCTION

This was the first study conducted in France to evaluate the impact of compliance levels for bisphosphonates, the most frequently prescribed first-line anti-osteoporotic treatment, on fracture risk.

METHODS

This retrospective nested case-control study included patients ≥ 50 years old, who were recorded in a random sample of French claims data, did not die between 2006 and 2013, and received ≥ 1 reimbursement for anti-osteoporotic treatment between 2007 and 2013. Cases (patients hospitalised for osteoporosis-related fractures) were matched to 1-3 controls (patients hospitalised for other reasons). Patients hospitalised for fractures within 12 months preceding the first delivery of anti-osteoporotic treatment or during the first 24 months of follow-up were excluded. Bisphosphonate compliance during the 24 months preceding hospitalisation was calculated by the Continuous measure of Medication Acquisition version 7 (CMA7). We evaluated the impact of bisphosphonate compliance (CMA7 ≥ 80%) and very good compliance levels (CMA7 > 90%) on fracture risk.

RESULTS

In the main analysis, the mean CMA7 values during the 24 months preceding hospitalisation were 48.4% for the 434 cases and 51.3% for the 1123 age-matched controls. An adjusted conditional logistic regression showed no significant impact (odds ratio: 0.851 [95% confidence interval: 0.668, 1.084]) of bisphosphonate compliance on fracture occurrence. In the sensitivity analysis, including one randomly selected control per case and only controls with CMA7 values > 90%, occurrence of fractures was lower (odds ratio: 0.741 [95% confidence interval: 0.608, 0.903]) among the 119 controls.

CONCLUSION

In conclusion, this study suggested that very high levels of compliance with bisphosphonates are necessary to induce significant decreases in fracture risk.

Structural, physico-mechanical and in-vitro bioactivity studies on SiO2-CaO-P2O5-SrO-Al2O3 bioactive glasses

Strontium based bioactive glasses have shown a better biocompatibility than calcia based bioactive glasses. In this report, we have shown that the bioactivity is found to be even more when we incorporate Al₂O₃ upto 1.5 mol% in SiO₂-CaO-P₂O₅-SrO bioactive glass. We have studied the structural, physico-mechanical and bioactive properties in these glasses with varying alumina concentration from 0.5 to 2.5 mol%. The bioactivity of the glasses is evaluated by in vitro test in simulated body fluid (SBF). The formation of hydroxy carbonated apatite layer (HCA) on the surface of glasses after immersion in SBF is identified by the XRD, FTIR and SEM. The substitution of Al₂O₃ for SrO in these glasses demonstrates a significant enhancement in compressive strength and elastic modulus. However cytotoxicity and cell viability assessed using human osteosarcoma U2-OS cell lines show the growth of the cells without causing any significant loss of viability and cell death upto 1.5 mol% addition of Al₂O₃. Osteosarcoma cells grow on the surface of bioglasses which make them biocompatible and fit for use in clinical trials.

THE USE OF VITAMINS AND MINERALS IN SKELETAL HEALTH: AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND THE AMERICAN COLLEGE OF ENDOCRINOLOGY POSITION STATEMENT

ABBREVIATIONS

25(OH)D = 25-hydroxyvitamin D; BMD = bone mineral density; CV = cardiovascular; GI = gastrointestinal; IOM = Institute of Medicine; PTH = parathyroid hormone; RCT = randomized controlled trial; αTF = α-tocopherol; ucOC = undercarboxylated osteocalcin; VKA = vitamin K antagonist; WHI = Women's Health Initiative.

Systemic administration of strontium ranelate to enhance the osseointegration of implants: systematic review of animal studies

The literature states that Strontium (Sr) is able to simultaneously stimulate bone formation and suppress bone resorption. Recent animal studies suggest that the systemic administration of Sr, in the form of strontium ranelate (SRAN), would enhance the osseointegration of implants. The purpose of the present study was to undertake a systematic review on animal studies evaluating the systemic administration of Sr to enhance the osseointegration of titanium implants and the remodeling of bone grafts. The MEDLINE (PubMed) and Scopus bibliographic databases were searched from 1950 to October 2017 for reports on the use of systemic and non-radioactive Sr to enhance the osseointegration of titanium implants and the remodeling of bone grafts in animals. The search strategy was restricted to English language publications using the combined terms: "strontium" and "implant or graft or biomaterial or bone substitute". Five studies were included, all related to the systemic administration of Sr in the form SRAN, and its effects on osseointegration of titanium implants. No studies on the use of SRAN-based therapy to enhance the remodeling of bone grafts were found. The studies differed notably with respect to the study population (healthy female rats, healthy male rats, and female rats with induced osteoporosis) and SRAN dose (ranging from 500 to 1000 mg/kg/day). Results were diverse, but a tendency suggesting positive influence of systemic SRAN administration on the osseointegration of titanium implants was observed. No major side-effects due to strontium administration were reported. Systemic Sr administration, in the form of SRAN, seems to enhance peri-implant bone quality and implant osseointegration in animals, however, at a moderate extent. Further studies, evaluating both the effects of this drug on implant osseointegration and the risk/benefit of its use, are needed to provide a rationale of this therapeutic approach.

Development of mesoporous bioactive glass nanoparticles and its use in bone tissue engineering

The incidence of bone disorders, from trauma, tissue degeneration due to ageing, pathological conditions to cancer, has been increasing. The pursuit for bone graft substitutes to assist in regenerating large bone defects is ever growing as a result of the shortage in conventional autografts and allografts, in addition to the associated risks of disease transmission. However, the use of alloplastic biomaterials is limited in clinical settings, as further investigations are required to address the properties of synthetic grafts to mimic the native bone tissue and deliver desirable biomolecules to facilitate bone regeneration. This review discusses the fundamental structure and properties of bone with the emphasis on organic and inorganic components that are important for the biomaterial design. The main focus will be on the advancement and usage of bioactive glass (BG) for bone tissue engineering due to its similarity to the natural inorganic constituent of bone. The various BG synthetic processes, modifications of composition, as well as the biomolecule delivery will be discussed in great detail. As the properties of BG are tuneable according to clinical needs, it creates a new paradigm in addition to displaying its superior potential for bone tissue engineering and translational medicine in the field of orthopedic surgery. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2878-2887, 2018.

A network meta-analysis on the short-term efficacy and adverse events of different anti-osteoporosis drugs for the treatment of postmenopausal osteoporosis

A network meta-analysis was conducted to compare the short-term efficacy and adverse events of different drugs for the treatment of postmenopausal osteoporosis (PMO), providing a more effective treatment for PMO. We initially searched through various databases like PubMed, Cochrane Library, and EMBASE from inception till October 2016. All randomized controlled trials (RCTs) of drugs for the treatment of PMO were included for direct and indirect comparison. A combination of direct and indirect evidence of different inhibitors of anti-diabetic drugs for treatment of PMO were considered for calculating the weighted mean difference (WMD) value or odd ratio (OR) value and to draw surface under the cumulative ranking (SUCRA) curves. Twenty-seven RCTs were ultimately incorporated into this network meta-analysis comprising of 48 200 patients suffering from PMO. The network meta-analysis revealed that compared with placebo, alendronate had better efficacy on improving bone mineral density (BMD) at lumbar spine, femoral neck, and total hip. Risedronate and raloxifene had relatively lower incidence of new vertebral fractures. The SUCRA analysis showed that alendronate had better efficacy on improving BMD, risedronate could significantly decrease the incidence of fresh fracture and bazedoxifene was relatively safe. The available evidence suggested that alendronate and risedronate might be the superior choices for the treatment of PMO, while bazedoxifene was a comparatively safer option for patients.

UK clinical guideline for the prevention and treatment of osteoporosis

INTRODUCTION

In 2008, the UK National Osteoporosis Guideline Group (NOGG) produced a guideline on the prevention and treatment of osteoporosis, with an update in 2013. This paper presents a major update of the guideline, the scope of which is to review the assessment and management of osteoporosis and the prevention of fragility fractures in postmenopausal women and men age 50 years or over.

METHODS

Where available, systematic reviews, meta-analyses and randomised controlled trials were used to provide the evidence base. Conclusions and recommendations were systematically graded according to the strength of the available evidence.

RESULTS

Review of the evidence and recommendations are provided for the diagnosis of osteoporosis, fracture-risk assessment, lifestyle measures and pharmacological interventions, duration and monitoring of bisphosphonate therapy, glucocorticoid-induced osteoporosis, osteoporosis in men, postfracture care and intervention thresholds.

CONCLUSION

The guideline, which has received accreditation from the National Institute of Health and Care Excellence (NICE), provides a comprehensive overview of the assessment and management of osteoporosis for all healthcare professionals who are involved in its management.

The efficacy and safety of vertebral fracture prevention therapies in post-menopausal osteoporosis treatment: Which therapies work best? a network meta-analysis

Objectives

Osteoporosis has become an increasing concern for older people as it may potentially lead to osteoporotic fractures. This study is designed to assess the efficacy and safety of ten therapies for post-menopausal women using network meta-analysis.

Methods

We conducted a systematic search in several databases, including PubMed and Embase. A random-effects model was employed and results were assessed by the odds ratio (OR) and corresponding 95% confidence intervals (CI). Furthermore, with respect to each outcome, each intervention was ranked according to the surface under the cumulative ranking curve (SUCRA) value.

Results

With respect to preventing new vertebral fractures (NVF), all ten drugs outperformed placebo, and etidronate proved to be the most effective treatment (OR 0.24, 95% CI 0.14 to 0.39). In addition, zoledronic acid and parathyroid hormone ranked higher compared with the other drugs. With respect to preventing clinical vertebral fractures (CVF), zoledronic acid proved to be the most effective drug (OR = 0.25, 95% CI 0.08 to 0.92), with denosumab as a desirable second option (OR = 0.48, 95% CI 0.22 to 0.96), when both were compared with placebo. As for adverse events (AE) and severe adverse events (SAE), no significant difference was observed. According to SUCRA, etidronate ranked first in preventing CVF; parathyroid hormone and zoledronic acid ranked highly in preventing NVF and CVF. Raloxifene was safe with a high rank in preventing AEs and SAEs though performed unsatisfactorily in efficacy.

Conclusions

This study suggests that, taking efficacy and safety into account, parathyroid hormone and zoledronic acid had the highest probability of satisfactory performance in preventing osteoporotic fractures.

Cite this article: G. Wang, L. Sui, P. Gai, G. Li, X. Qi, X. Jiang. The efficacy and safety of vertebral fracture prevention therapies in post-menopausal osteoporosis treatment: Which therapies work best? a network meta-analysis. Bone Joint Res 2017;6:452–463. DOI: 10.1302/2046-3758.67.BJR-2016-0292.R1.

Enhanced bone formation by strontium modified calcium sulfate hemihydrate in ovariectomized rat critical-size calvarial defects

The development of a new generation of biomaterials with high osteogenic ability for treatment of osteoporotic fractures is being intensively investigated. The objective of this paper was to investigate new bone formation in an ovariectomized rat (OVX rat) calvarial model of critical size bone defects filled with Sr-containing α-calcium sulfate hemihydrate (SrCSH) cement compared to an α-calcium sulfate hemihydrate (α-CSH) cement and empty defect. X-ray diffraction analysis verified the partial substitution of Sr²⁺ for Ca²⁺ did not change the phase composition of α-CSH. Scanning electron microscopy showed that Sr-substituted α-CSH significantly increased the surface roughness. The effects of Sr substitution on the biological properties of SrCSH cement were evaluated by adhesion, proliferation, alkaline phosphatase (ALP) activity of osteoblast-like cells MC3T3-E1. The results showed that SrCSHs enhanced MC3T3-E1 cell proliferation, differentiation, and ALP activity. Furthermore, SrCSH cement was used to repair critical-sized OVX rat calvarial defects. The in vivo results revealed that SrCSH had good osteogenic capability and stimulated new blood vessel formation in a critical sized OVX calvarial defect within 12 weeks, suggesting that SrCSH cement has more potential for application in bone tissue regeneration.

Strontium and strontium ranelate: Historical review of some of their functions

The review covers historical and last decade's scientific literature on the biological and clinical role of strontium (Sr) and strontium ranelate (Sr RAN). It enrols the description of the main effects of Sr on supportive tissue, its proven and possible morphopathogenetical mechanisms and the interaction with the bone, and especially focuses on the Sr ability to inhibit osteoclasts and affect the programmed cell death. The main experimental and clinical experience regarding the Sr RAN influence in the treatment of osteoporosis and the search for correct doses is also highlighted. The review gives insight into the role of Sr/Sr RAN on stem cells, apoptosis, animal and clinical research.

New Drug Treatments for Osteoarthritis: What Is on the Horizon?

Osteoarthritis (OA) is the most common form of arthritis, yet has historically lagged far behind rheumatoid arthritis in terms of drug development. Despite the many challenges presented by clinical trials in OA, improvements in our understanding of disease pathogenesis and a move to treat pain, as well as underlying disease process, mean there are now many new pharmacological therapies currently in various stages of clinical trials. The medical need for these therapies and the evidence for recent tissue and molecular targets are reviewed. Current therapeutic examples in each area are discussed, including both novel therapeutics and existing agents which may be repurposed from other disease areas. Some challenges remain, but opportunities for improving symptoms and disease process in OA in the clinic with new pharmacological agents would appear to be on the close horizon.

Effects of Strontium Ranelate on Spinal Interbody Fusion Surgery in an Osteoporotic Rat Model

Osteoporosis is a bone disease that afflicts millions of people around the world, and a variety of spinal integrity issues, such as degenerative spinal stenosis and spondylolisthesis, are frequently concomitant with osteoporosis and are sometimes treated with spinal interbody fusion surgery. Previous studies have demonstrated the efficacy of strontium ranelate (SrR) treatment of osteoporosis in improving bone strength, promoting bone remodeling, and reducing the risk of fractures, but its effects on interbody fusion surgery have not been adequately investigated. SrR-treated rats subjected to interbody fusion surgery exhibited significantly higher lumbar vertebral bone mineral density after 12 weeks of treatment than rats subjected to the same surgery but not treated with SrR. Furthermore, histological and radiographic assessments showed that a greater amount of newly formed bone tissue was present and that better fusion union occurred in the SrR-treated rats than in the untreated rats. Taken together, these results show significant differences in bone mineral density, PINP level, histological score, SrR content and mechanical testing, which demonstrate a relatively moderate effect of SrR treatment on bone strength and remodeling in the specific context of recovery after an interbody fusion surgery, and suggest the potential of SrR treatment as an effective adjunct to spinal interbody fusion surgery for human patients.

Dose-dependent Effects of Strontium Ranelate on Ovariectomy Rat Bone Marrow Mesenchymal Stem Cells and Human Umbilical Vein Endothelial Cells

In clinic, strontium ranelate (SrR) is a useful drug to treat osteoporosis by orally taken method, but some side effect appeared in recent years. The aim of this study is to evaluate the effectiveness and safety of SrR on cells by direct application, to study the possibility of local application of this drug. Qualitative ALP staining, quantitative ALP activity assay, alizarin red staining, realtime PCR and westernblot assay were used to evaluate the osteogenesis ability of SrR under normal or osteogenic induction environment of ovariectomy bone marrow mesenchymal stem cells (OVX-BMSCs). The angiogenesis ability of SrR was studied by immunofluorescence staining of CD31 and vWF of OVX-BMSCs under angiogenesis induction environment, transwell, tubeformation and realtime PCR assay of HUVECs. Signaling pathway of PI3K/AKT/mTOR was also studied. The result demonstrated that SrR could enhance proliferation and osteogenic differentiation of OVX-BMSCs. The osteogenesis effect of SrR has been proved by the better performed of ALP activity, alizarin red staining and the remarkable up-regulation of ALP, Col-I, Runx2, OCN, BMP-2, BSP, OPG of the OVX-BMSCs, and reduction of RANKL. In addition, SrR promotes angiogenesis differentiation of both OVX-BMSCs and HUVECs. Higher intensity of immunostaining of CD31 and vWF, better result of transwell and tubeformation assay could be observed in SrR treated group, and increasing mRNA levels of VEGF and Ang-1 in the OVX-BMSCs, VEGF in HUVECs were learnt. Signaling pathway assay showed that PI3K/AKT/mTOR signaling pathway was involved in this SrR triggered angiogenesis procedure. The thrombosis marker ET-1, PAI-1 and t-PA were up-regulated, but no significant differences for low concentration (<0.5mM). The concentration between 0.25-0.5mM may be more appropriate for local application, and locally application of SrR could be considered as a promising way for bone regeneration.

Influence of single and binary doping of strontium and lithium on in vivo biological properties of bioactive glass scaffolds

Effects of strontium and lithium ion doping on the biological properties of bioactive glass (BAG) porous scaffolds have been checked in vitro and in vivo. BAG scaffolds were prepared by conventional glass melting route and subsequently, scaffolds were produced by evaporation of fugitive pore formers. After thorough physico-chemical and in vitro cell characterization, scaffolds were used for pre-clinical study. Soft and hard tissue formation in a rabbit femoral defect model after 2 and 4 months, were assessed using different tools. Histological observations showed excellent osseous tissue formation in Sr and Li + Sr scaffolds and moderate bone regeneration in Li scaffolds. Fluorochrome labeling studies showed wide regions of new bone formation in Sr and Li + Sr doped samples as compared to Li doped samples. SEM revealed abundant collagenous network and minimal or no interfacial gap between bone and implant in Sr and Li + Sr doped samples compared to Li doped samples. Micro CT of Li + Sr samples showed highest degree of peripheral cancellous tissue formation on periphery and cortical tissues inside implanted samples and vascularity among four compositions. Our findings suggest that addition of Sr and/or Li alters physico-chemical properties of BAG and promotes early stage in vivo osseointegration and bone remodeling that may offer new insight in bone tissue engineering.

Strontium ranelate improves the interaction of osteoblastic cells with titanium substrates: Increase in cell proliferation, differentiation and matrix mineralization

We describe direct effects of strontium ranelate on the interaction of osteoblastic cells with different titanium substrates. Our goal was to better understand the potential of this drug for improving the efficacy of bone implants. Treatment was done with 0.12 and 0.5 mM Sr(2+) of strontium ranelate in cell culture. We analyzed cell response to the drug on titanium substrates with surface topographies obtained using acid etching, electro-erosion processing, sandblasting, and machine-tooling. Treatment preserved the initial cell adhesion to the substrates, cell shape parameters (area, aspect ratio, circularity, and solidity), and the orientation of cells on grooved surfaces. However, both concentrations of the drug increased cell proliferation in all substrates. Moreover, a dose-dependent increase in alkaline phosphatase activity and in the production of mineralized matrix with typical features of bone tissue was shown. The observed effects were similar in the different substrates. In conclusion, strontium ranelate improved the interaction of osteoblastic cells with titanium substrates, increasing cell proliferation and differentiation into mature osteoblasts and the production of bone-like mineralized matrix for all substrates. This study highlights a promising role of strontium ranelate on enhancing the clinical success of bone implants, particularly in patients with osteoporosis.

Increased risk of strontium ranelate-related SJS/TEN is associated with HLA

Severe adverse drug reactions (ADR) of Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) in some patients receiving strontium ranelate have been reported, but the risk factors are unclear. We show that HLA-A*33:03 and B*58:01 are significantly associated with patients who developed SJS/TEN; and provide the first evidence that genetic risk factors are involved in strontium ranelate-associated SJS/TEN.

INTRODUCTION

In this study, HLA as a genetic risk factor was assessed among osteoporotic patients prescribed with strontium ranelate that developed severe cutaneous adverse drug reactions (SCARs) compared with those who were tolerant.

METHODS

Genomic DNA isolated from peripheral blood mononuclear cells (PBMCs) of patients was HLA typed using sequencing-based typing method to determine their HLA profiles.

RESULTS

Osteoporotic patients who are currently on strontium ranelate were enrolled in the study (n = 76). Tolerant controls were defined as patients who received strontium ranelate for a minimum of 3 months (range 3 months to 8 years) with no reports of any cutaneous reactions as these reactions usually occur within the first 12 weeks after starting treatment. Retrospective cases of SJS/TEN were also identified (n = 5). The majority of the accrued samples were of Han Chinese descent: controls (n = 72) and cases (n = 4). All cases and controls were genotyped at four HLA genes, namely HLA-A, HLA-B, HLA-C, and HLA-DRB1. In comparing the samples of Han Chinese descent (72 controls and 4 cases), we found significant associations with HLA-A*33:03 (p = 0.002) and HLA-B*58:01 (p = 0.023). There was no significant association with any HLA-C or HLA-DRB1 alleles.

CONCLUSIONS

This study reveals that the occurrence of SJS/TEN in Han Chinese patients receiving strontium ranelate is HLA associated. This has important clinical implications for understanding the underlying mechanisms for this ADR as well as evaluating the potential role of genetic pre-screening for osteoporotic patients who may be prescribed strontium ranelate.

Evaluation and Treatment of Osteoporosis

As the population ages, the rates of osteoporotic fractures will increase, with postmenopausal women incurring most of these fractures. Diagnosis and treatment of osteoporosis are extremely important. Dual-energy x-ray absorptiometry scan screening is recommended in all women more than 65 years of age or in women aged 50 to 64 years with certain risk factors. Treatment should be considered if osteoporosis is present, there is a history of fragility fracture, or in the setting of osteopenia plus high risk for fracture.

Effects of strontium ranelate on markers of cardiovascular risk in postmenopausal osteoporotic women

Recent pooled analyses have shown that strontium ranelate increases the incidence of venous thromboembolism and non-fatal myocardial infarction, but no explanations were given. The aim of our study was to assess the effects a 12-month treatment with strontium ranelate on hemostasis factors and markers of cardiovascular risk in postmenopausal osteoporotic women. Forty osteoporotic postmenopausal women received orally strontium ranelate 2 g daily, plus calcium and colecalcipherol for 12 months. Forty postmenopausal osteopenic women matched for age, menopausal age, and body mass index served as controls and received orally calcium and colecalcipherol for 12 months. Biochemical cardiovascular risk factors and hemostatic indices were assayed prior to treatment, and after 3, 6, and 12 months of therapy. These indices included fibrinogen, fasting glucose, total serum cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, plasma levels of D-dimer, homocysteine, partial thromboplastin time, and prothrombin time. In addition, we evaluated possible changes in blood pressure and occurrence of venous thromboembolic events. At baseline, no statistically significance was observed between the two groups except for bone mineral density at lumbar spine, femoral neck, and total femur, which was lower in strontium ranelate group. After 12 months of treatment, there was no statistically significant change in cardiovascular risk factors and hemostatic parameters. None of the 40 women developed any clinical venous thromboembolic event. A 12-month treatment with strontium ranelate did not alter hemostasis factors or markers of cardiovascular risk, suggesting that reported increased risk of venous thromboembolism and myocardial infarction with strontium is mediated by other factors.

Strontium Ranelate Reduces the Fracture Incidence in a Growing Mouse Model of Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a genetic bone dysplasia characterized by brittle bones with increased fracture risk. Although current treatment options to improve bone strength in OI focus on antiresorptive bisphosphonates, controlled clinical trials suggest they have an equivocal effect on reducing fracture risk. Strontium ranelate (SrR) is a promising therapy with a dual mode of action that is capable of simultaneously maintaining bone formation and reducing bone resorption, and may be beneficial for the treatment of OI. In this study, SrR therapy was investigated to assess its effects on fracture frequency and bone mass and strength in an animal model of OI, the oim/oim mouse. Three-week-old oim/oim and wt/wt mice were treated with either SrR or vehicle (Veh) for 11 weeks. After treatment, the average number of fractures sustained by SrR-treated oim/oim mice was significantly reduced compared to Veh-treated oim/oim mice. Micro-computed tomographic (μCT) analyses of femurs showed that both trabecular and cortical bone mass were significantly improved with SrR treatment in both genotypes. SrR significantly inhibited bone resorption, whereas bone formation indices were maintained. Biomechanical testing revealed improved bone structural properties in both oim/oim and wild-type (wt/wt) mice under the treatment, whereas no significant effects on bone brittleness and material quality were observed. In conclusion, SrR was able to effectively reduce fractures in oim/oim mice by improving bone mass and strength and thus represents a potential therapy for the treatment of pediatric OI. © 2015 American Society for Bone and Mineral Research.

Polycaprolactone-laponite composite scaffold releasing strontium ranelate for bone tissue engineering applications

We report polycaprolactone-laponite composite scaffold for the controlled release of strontium ranelate (SRA), a drug for osteoporosis. Laponite-SRA complex with electrostatic interaction between the drug and laponite was obtained through an aqueous phase reaction. Structural evaluation verified complexation of the bulky SRA molecules with the negatively charged laponite tactoid surfaces, leading to extended ordering of the tactoids, leaving behind the interlayer spacing of the laponite unchanged. The laponite-SRA complex was solution blended with polycaprolactone to obtain composite scaffolds. The strategy was found improving the dispersibility of laponite in PCL due to partial organomodification imparted through interaction with the SRA. The composite scaffolds with varying laponite-SRA complex content of 3-12wt% were evaluated in vitro using human osteosarcoma cells. It was confirmed that an optimum composition of the scaffold with 3wt% laponite-SRA complex loading would be ideal for obtaining enhanced ALP activity, by maintaining cell viability.

Effect of osteoporosis medications on fracture healing

Antiosteoporotic medications are often used to concurrently treat a patient's fragility fractures and underlying osteoporosis. This review evaluates the existing literature from animal and clinical models to determine these drugs' effects on fracture healing. The data suggest that these medications may enhance bone healing, yet more thorough prospective studies are warranted. Pharmacologic agents that influence bone remodeling are an essential component of osteoporosis management. Because many patients are first diagnosed with osteoporosis when presenting with a fragility fracture, it is critical to understand how osteoporotic medications influence fracture healing. Vitamin D and its analogs are essential for the mineralization of the callus and may also play a role in callus formation and remodeling that enhances biomechanical strength. In animal models, antiresorptive medications, including bisphosphonates, denosumab, calcitonin, estrogen, and raloxifene, do not impede endochondral fracture healing but may delay repair due to impaired remodeling. Although bisphosphonates and denosumab delay callus remodeling, they increase callus volume and result in unaltered biomechanical properties. Calcitonin increases cartilage formation and callus maturation, resulting in improved biomechanical properties. Parathyroid hormone, an anabolic agent, has demonstrated promise in animal models, resulting in accelerated healing with increased callus volume and density, more rapid remodeling to mature bone, and improved biomechanical properties. Clinical data with parathyroid hormone have demonstrated enhanced healing in distal radius and pelvic fractures as well as postoperatively following spine surgery. Strontium ranelate, which may have both antiresorptive and anabolic properties, affects fracture healing differently in normal and osteoporotic bone. While there is no effect in normal bone, in osteoporotic bone, strontium ranelate increases callus bone formation, maturity, and mineralization; forms greater and denser trabeculae; and improves biomechanical properties. Further clinical studies with these medications are needed to fully understand their effects on fracture healing in order to simultaneously treat fragility fractures and underlying osteoporosis.

Treatments for post-menopausal osteoporotic women, what's new? How can we manage long-term treatment?

Since the mid-1980s, postmenopausal osteoporosis (PMO) has been considered a serious public health concern because of the associated fractures. Pharmacological therapies that effectively reduce the number of fractures by improving bone mass have been and are being developed continuously. Most current agents inhibit bone loss by reducing bone resorption, but emerging therapies may increase bone mass by stimulating bone formation. Furthermore, nowadays, the most representative pharmaceuticals have been prescribed long enough to include the reporting of some adverse effects. This review discusses osteoporotic drugs that are approved or are under investigation for the treatment of post-menopausal women (PMW), paying particular attention to long-term treatments.

Structural analysis of xSrO-(50 - x)CaO-50P2O5 glasses with x=0, 5, or 10 mol% for potential use in a local delivery system for osteomyelitis treatment

The introduction of ions into a local delivery matrix is one method of managing degradation and subsequent release of the incorporated therapeutic agents. Of interest in this study was whether we could modify the structural nature of calcium polyphosphate (CPP) glass and the subsequent therapeutic potential of this local delivery matrix with inclusion of strontium (Sr). We found that adding 10 mol% Sr significantly increased the density and chain length of the glass. There was no significant impact of Sr doping on the subsequent loading of vancomycin into the matrix, or the matrix porosity. The noted differences in structural stability, ion release, and vancomycin release between the un-doped CPP matrices and 10 mol% Sr-doped CPP matrices in vitro are likely a result of a decrease in glass disorder upon Sr addition to the glass and preferential retention of Sr over Ca during matrix degradation. This study has provided further evidence that Sr incorporation may serve to both manipulate antibiotic release from the amorphous CPP matrix and provide a potential source of therapeutic ions for enhanced bone regeneration.

The effects of strontium on bone mineral: A review on current knowledge and microanalytical approaches

The interest in effects of strontium (Sr) on bone has greatly increased in the last decade due to the development of the promising drug strontium ranelate. This drug is used for treating osteoporosis, a major bone disease affecting hundreds of millions of people worldwide, especially postmenopausal women. The novelty of strontium ranelate compared to other treatments for osteoporosis is its unique effect on bone: it simultaneously promotes bone formation by osteoblasts and inhibits bone resorption by osteoclasts. Besides affecting bone cells, treatment with strontium ranelate also has a direct effect on the mineralized bone matrix. Due to the chemical similarities between Sr and Ca, a topic that has long been of particular interest is the incorporation of Sr into bones replacing Ca from the mineral phase, which is composed by carbonated hydroxyapatite nanocrystals. Several groups have analyzed the mineral produced during treatment; however, most analysis were done with relatively large samples containing numerous nanocrystals, resulting thus on data that represents an average of many crystalline domains. The nanoscale analysis of the bone apatite crystals containing Sr has only been described in a few studies. In this study, we review the current knowledge on the effects of Sr on bone mineral and discuss the methodological approaches that have been used in the field. In particular, we focus on the great potential that advanced microscopy and microanalytical techniques may have on the detailed analysis of the nanostructure and composition of bone apatite nanocrystals produced during treatment with strontium ranelate.

Strontium- and calcium-containing, titanium-stabilised phosphate-based glasses with prolonged degradation for orthopaedic tissue engineering

Strontium- and calcium-releasing, titanium-stabilised phosphate-based glasses with a controlled degradation rate are currently under development for orthopaedic tissue engineering applications. Ca and/or Sr were incorporated at varying concentrations in quaternary phosphate-based glasses, in order to promote osteoinduction. Ti was incorporated at a fixed concentration in order to prolong degradation. Glasses of the general formula (P₂O₅)–(Na₂O)–(TiO₂)–(CaO)–(SrO) were prepared via the melt-quench technique. The materials were characterised by energy-dispersive X-ray spectroscopy, X-ray diffraction, ³¹P magic angle spinning nuclear magnetic resonance, Fourier transform infrared spectroscopy, differential thermal analysis and density determination. The dissolution rate in distilled water was determined by measuring mass loss, ion release and pH change over a two-week period. In addition, the cytocompatibility and alkaline phosphatase activity of an osteoblast-like cell line cultured on the surface of glass discs was assessed. The glasses were shown to be amorphous and contained Q¹, Q² and Q³ species. Fourier transform infrared spectroscopy revealed small changes in the glass structure as Ca was substituted with Sr and differential thermal analysis confirmed a decrease in crystallisation temperature with increasing Sr content. Degradation and ion release studies also showed that mass loss was positively correlated with Sr content. These results were attributed to the lower electronegativity of Sr in comparison to Ca favouring the formation of phosphate-based mineral phases. All compositions supported cell proliferation and survival and induced at least 2.3-fold alkaline phosphatase activity relative to the control. Glass containing 17.5 mol% Sr had 3.6-fold greater alkaline phosphatase activity than the control. The gradual release of Ca and Sr supported osteoinduction, indicating their potential suitability in orthopaedic tissue engineering applications.

Interactive effects of vitamin D3 and strontium on performance, nutrient retention and bone mineral composition in laying hens

BACKGROUND

Strontium is currently prescribed for patients with osteoporosis to increase bone density and reduce bone fractures but its relevance in animal nutrition is obscure. In order to investigate the effect of supplemental strontium and vitamin D3 on performance, egg quality and skeletal integrity in poultry a total of 108 laying hens, 99 weeks of age, were fed three levels of strontium (0, 500, 1000 mg kg(-1) ) and two levels of vitamin D3 (2500, 5,000 iu kg(-1)) over a 12-week period.

RESULTS

There was an improvement (P < 0.05) in egg production and feed conversion efficiency with strontium at 500 mg kg(-1) and a significant increase in egg weight in those hens fed additional vitamin D3 . Supplemental strontium increased phosphorus, sodium and strontium retention in birds fed 2500 iu D3 kg(-1) but reduced phosphorus, sodium and strontium retention in birds fed 5000 iu D3 kg(-1), resulting in an interaction (P < 0.01) between strontium and vitamin D3 . Addition of 5000 iu D3 kg(-1) increased egg weight (P < 0.05); predominantly by increased albumen content (P < 0.05), whereas strontium supplementation reduced egg weight (P < 0.001). Similarly, 5000 iu kg(-1) D3 increased apparent metabolizable energy (P < 0.05); in contrast, strontium supplementation reduced (P < 0.05) apparent metabolizable energy.

CONCLUSION

The addition of 500 mg kg(-1) strontium significantly improved egg production and feed efficiency; however, further investigation needs to be undertaken to refine the optimum level of strontium required to maximize hen performance. The interrelationship between strontium and vitamin D3 requires further exploratory study.

Complications and institutionalization are almost doubled after second hip fracture surgery in the elderly patient

PURPOSE

To determine patient and hip fracture characteristics, early postoperative complication rate, and need for institutionalization at the time of discharge from the hospital in patients treated for a second contralateral hip fracture.

METHODS

During a 6-year period (2003-2009), 71 patients (60 women and 11 men; age range, 54-94 years) underwent first hip fracture surgery and subsequent contralateral hip fracture surgery at our hospital. Variables, including age, gender, American Society of Anesthesiologists classification (ASA), AO fracture classification, time between both hip fractures, rate and severity of early postoperative complications, and destination of discharge were obtained from the electronic medical records. Data from both hospitalization periods were compared.

RESULTS

Forty-six percent of second hip fractures occurred within 2 years after the first hip fracture. After the first hip fracture surgery, 13 patients had 1 or multiple complications compared with 23 patients after a second hip fracture surgery (P = 0.02). The mean time (±SD) between the first and second hip fractures in patients without complications after the second injury was 4.3 (±4.2) years, compared with 2.6 (±2.1) years in patients with complications after the second injury (P = 0.03). The mean ASA classification of patients without complications after the second hip fracture surgery was 2.6 (±0.6) versus 3.0 (±0.6) in patients with complications (P = 0.04). After the first hip fracture surgery, 27 patients (38%) were discharged to an institutional care facility, whereas 72% of patients resided at an institutional care facility after a second hip fracture.

CONCLUSIONS

Early complication rate in patients sustaining a second contralateral hip fracture was almost twice that documented after the first hip fracture. After the second hip fracture surgery, most patients resided in an institutional care facility.

LEVEL OF EVIDENCE

Prognostic level II. See Instructions for Authors for a complete description of levels of evidence.

Evaluation of injectable strontium-containing borate bioactive glass cement with enhanced osteogenic capacity in a critical-sized rabbit femoral condyle defect model

The development of a new generation of injectable bone cements that are bioactive and have enhanced osteogenic capacity for rapid osseointegration is receiving considerable interest. In this study, a novel injectable cement (designated Sr-BBG) composed of strontium-doped borate bioactive glass particles and a chitosan-based bonding phase was prepared and evaluated in vitro and in vivo. The bioactive glass provided the benefits of bioactivity, conversion to hydroxyapatite, and the ability to stimulate osteogenesis, while the chitosan provided a cohesive biocompatible and biodegradable bonding phase. The Sr-BBG cement showed the ability to set in situ (initial setting time = 11.6 ± 1.2 min) and a compressive strength of 19 ± 1 MPa. The Sr-BBG cement enhanced the proliferation and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells in vitro when compared to a similar cement (BBG) composed of chitosan-bonded borate bioactive glass particles without Sr. Microcomputed tomography and histology of critical-sized rabbit femoral condyle defects implanted with the cements showed the osteogenic capacity of the Sr-BBG cement. New bone was observed at different distances from the Sr-BBG implants within eight weeks. The bone-implant contact index was significantly higher for the Sr-BBG implant than it was for the BBG implant. Together, the results indicate that this Sr-BBG cement is a promising implant for healing irregularly shaped bone defects using minimally invasive surgery.

Three-dimensional printed strontium-containing mesoporous bioactive glass scaffolds for repairing rat critical-sized calvarial defects

The development of a new generation of biomaterials with high osteogenic ability for fast osseointegration with host bone is being intensively investigated. In this study, we have fabricated three-dimensional (3-D) strontium-containing mesoporous bioactive glass (Sr-MBG) scaffolds by a 3-D printing technique. Sr-MBG scaffolds showed uniform interconnected macropores (∼400μm), high porosity (∼70%) and enhanced compressive strength (8.67±1.74MPa). Using MBG scaffolds as a control, the biological properties of Sr-MBG scaffolds were evaluated by apatite-forming ability, adhesion, proliferation, alkaline phosphatase activity and osteogenic gene expression of osteoblast-like cells MC3T3-E1. Furthermore, Sr-MBG scaffolds were used to repair critical-sized rat calvarial defects. The results showed that Sr-MBG scaffolds possessed good apatite-forming ability and stimulated MC3T3-E1 cell proliferation and differentiation. Importantly, the in vivo results revealed that Sr-MBG scaffolds had good osteogenic capability and stimulated new blood vessel formation in critical-sized rat calvarial defects within 8 weeks. Therefore, 3-D printed Sr-MBG scaffolds with favorable pore structure and high osteogenic ability have more potential applications in bone regeneration.

A comparison of adverse event and fracture efficacy data for strontium ranelate in regulatory documents and the publication record

OBJECTIVE

Recently, the European Medicines Agency reported that strontium ranelate increases myocardial infarction risk in postmenopausal women, 8.5 years after it was registered for use in osteoporosis. Unreported serious adverse events in clinical trials for other pharmaceuticals have been described in recent years. We assessed reporting of adverse events and fracture efficacy of strontium.

METHODS

We compared data on adverse effects (myocardial infarction, venous thromboembolism and pulmonary embolism) and fracture efficacy of strontium in publicly available regulatory documents with data in publications retrieved from searching PubMed.

RESULTS

We identified 5 regulatory documents and 9 primary publications of 7 randomised, placebo-controlled trials of strontium that reported relevant data. We identified several areas of concern in these reports: the increased risk of myocardial infarction with strontium was not identified in a pivotal phase 3 clinical trial despite specific regulatory review of cardiovascular events; data on myocardial infarction were not included in any primary publication; increased risks of venous thromboembolism and pulmonary embolism with strontium were not reported in either of the phase 3 clinical trials; data on venous thromboembolism were reported in only 5 of 9 primary publications, data on pulmonary embolism in only 2 of 9 primary publications, and either was discussed in <50% of subsequent review articles. There were differences in participant numbers, fracture cases and venous thromboembolism cases between regulatory documents and primary publications. Based on all available data from primary publications and regulatory documents, the number of fractures prevented by strontium use is similar to the number of extra cases of venous thromboembolism, pulmonary embolism and myocardial infarction caused by strontium use.

CONCLUSIONS

The risks of strontium use are similar to the benefits. Full disclosure of the clinical trial data and regulatory documents would allow clinicians and their patients to decide whether use of the drug is worthwhile.

Feasibility of osteosynthesis of fractured cadaveric hips following preventive elastomer femoroplasty

BACKGROUND

In vitro cadaveric studies showed that elastomer femoroplasty prevents displacement of fracture parts after proximal hip fracture allowing for conservative treatment. In the event that secondary displacement does occur, the purpose of this present study was to determine the feasibility of performing osteosynthesis of a fractured hip after preventive treatment with elastomer femoroplasty.

METHODS

Ten pairs of human cadaveric femurs were fractured in a simulated fall configuration. From each pair, one femur was randomly selected for elastomer femoroplasty prior to fracture generation and the contralateral femur was used as control. Following hip fracture generation, osteosynthesis was performed in all femurs. The operative time per case, technical difficulties during the procedure, and postoperative energy-to-failure load were recorded.

RESULTS

The mean (SD) time to perform osteosynthesis was 20 (6) minutes in the control-group and 19 (5) minutes in the elastomer femoroplasty-group (P=0.69). During osteosynthesis of the fractured hip in the elastomer femoroplasty-group, no difficulties including the need for additional instruments to remove elastomer from the proximal femur were recorded. Postoperative energy-to-failure load was similar in the control-group and the elastomer femoroplasty-group.

CONCLUSION

Fixation with routine osteosynthesis of displaced cadaveric hip fractures is not hindered by the presence of previously injected elastomer.

Cardiac concerns associated with strontium ranelate

Introduction: Strontium ranelate is proven to reduce vertebral and non-vertebral fracture risk in osteoporosis. Concerns about cardiac safety have led to a new contraindication to strontium ranelate in patients with uncontrolled hypertension and/or current or past history of ischaemic heart disease, peripheral arterial disease and/or cerebrovascular disease.

Areas covered: A literature search was performed; data were also collected from the European Medicines Agency website. Randomised controlled trial (RCT) data indicate a higher incidence of non-adjudicated myocardial infarction (MI) with strontium ranelate versus placebo (1.7 vs 1.1%; odds ratio [OR]: 1.6; 95% CI: 1.07 – 2.38; p = 0.020) (Mantel-Haenzel estimate of the OR). There was no increase in cardiovascular mortality. MI risk was mitigated by excluding patients with cardiovascular contraindications (OR: 0.99; 95% CI: 0.48 – 2.04; p = 0.988). Three observational studies performed in the context of real-life medical practice in the UK and Denmark did not report a signal.

Expert opinion: The increased risk for cardiac events with strontium ranelate has been detected in RCTs but not in real life. Excluding patients with cardiovascular contraindications appears to be an effective measure for controlling the risk of MI. Strontium ranelate remains a useful therapeutic alternative in patients with severe osteoporosis without cardiovascular contraindications who are unable to take another osteoporosis treatment.

Current challenges in the treatment of osteoporosis: an opportunity for bazedoxifene

BACKGROUND

Osteoporosis affects millions of postmenopausal women worldwide. Osteoporosis-related fractures can lead to chronic pain, disability, systemic complications, and increased risk of recurrent fractures, resulting in increased healthcare costs and mortality. Because currently available therapies have unique benefit/risk profiles, challenges remain in selecting the most appropriate treatment for each osteoporotic woman. RESEARCH AND RESULTS: Bazedoxifene (BZA), a new selective estrogen receptor modulator, is being developed for postmenopausal osteoporosis. In a 3 year, global, phase 3 study, BZA significantly reduced the risk of new vertebral fractures and nonvertebral fractures in women with higher baseline fracture risk compared with placebo. In two extensions of this study, the efficacy of BZA in reducing vertebral fracture risk was sustained over 7 years. BZA improved lumbar spine and total hip bone mineral density compared with placebo at 3 and 5 years, and demonstrated a favorable safety/tolerability profile, with no endometrial or breast stimulation. BZA was cost-effective compared with raloxifene in a 3 year, head-to-head comparative trial. Indirect comparisons further suggest that BZA may be as effective as bisphosphonates in reducing risk of nonvertebral fractures in women at high risk of fracture. BZA demonstrated efficacy and safety for treating postmenopausal osteoporosis over 7 years, particularly in women at a higher fracture risk.

CONCLUSION

Because of its specific pharmacologic profile, BZA may be appropriate for postmenopausal women seeking a tolerable, safe, effective, and cost-effective long-term osteoporosis treatment.

How long should we treat?

Osteoporosis is a chronic disease, for which effective drugs are available. These drugs have reduced the risk of osteoporosis-related fractures in robust trials of 3-5 years duration. There is no evidence of anti-fracture efficacy for treatments of longer duration. The consequences of stopping treatments are very different for the different molecules. Bisphosphonates can be safely discontinued after 3-5 years of treatment if there was optimal adherence and if patients are no longer osteoporotic. This discontinuation cannot be applied in patients with recent fractures or for other treatments. Safety of prolonged treatment is a huge concern which must be managed appropriately. The decision of a prolonged treatment is driven by the underlying risk of fracture. This risk must be assessed regularly in order to share with the patient the benefit-risk ratio of prolonged treatment.