Anabolic agents: what is beyond osteoporosis?

Exercise alleviates osteoporosis by regulating the secretion of the Senescent Associated Secretory Phenotype

As the elderly population grows, the number of patients with metabolic bone diseases such as osteoporosis has increased sharply, posing a significant threat to public health and social economics. Although pharmacological therapies for osteoporosis demonstrate therapeutic benefits, their prolonged use is associated with varying degrees of adverse effects. As a non-pharmacological intervention, exercise is widely recognized for its cost-effectiveness, safety, and lack of toxic side effects, making it a recommended treatment for osteoporosis prevention and management. Previous studies have demonstrated that exercise can improve metabolic bone diseases by modulating the Senescent Associated Secretory Phenotype (SASP). However, the mechanisms through which exercise influences SASP remain unclear. Therefore, this review aims to summarize the effects of exercise on SASP and elucidate the specific mechanisms by which exercise regulates SASP to alleviate osteoporosis, providing a theoretical basis for osteoporosis through exercise and developing targeted therapies.

Psoas muscle cross sectional area relates to bone density and microarchitecture in candidates for spine fusion surgery

Prior studies demonstrate that muscle and bone health are integrally related, and both independently impact orthopedic surgery outcomes. However, relationships between bone density, in vivo microarchitecture, and muscle area have not been previously investigated in orthopedic surgery patients. This study assessed associations between psoas cross sectional area (CSA), bone mineral density (BMD), and microstructure in a cohort undergoing spine fusion. Pre-operatively, bilateral psoas CSA was measured on axial lumbar spine CT in the L3-L4 disc space. To adjust for body size, Psoas Muscle Index (PMI) was calculated (CSA divided by the square of patient height). High resolution peripheral quantitative CT (HR-pQCT, XtremeCT2) assessed volumetric BMD (vBMD), cortical (Ct) and trabecular (Tb) microarchitecture at the distal radius and tibia. Areal BMD (aBMD) was measured by DXA at the lumbar spine (LS), total hip (TH), femoral neck (FN), and the 1/3 radius (1/3R). Pearson correlations related psoas CSA and bone imaging parameters before and after correcting for height and weight. Among 88 patients included, mean age was 63 ± 12 years, BMI was 28 ± 7 kg/m2, 47 (53 %) were female. Larger psoas CSA was associated with higher vBMD, greater Ct thickness and better Tb microarchitecture (higher Tb number and lower Tb separation) at the tibia and radius. Larger psoas CSA was also associated with greater aBMD at TH and FN bilaterally and 1/3R (r 0.33 to 0.61; p < 0.002 for all comparisons). Psoas CSA was not associated with aBMD at the LS. Similar results were observed when relating PMI, and adjusting for age, height and weight to HR-pQCT and DXA measurements. Investigation of subgroups by sex demonstrated that relationships were similar magnitude among women but not the men. Patients who underwent primary compared to revision spine surgery had similar associations. Our results demonstrate a link between psoas muscle size and peripheral bone microarchitecture among patients undergoing posterior lumbar spinal fusion. Given the importance of both muscle and skeletal integrity to the success of spine surgery, further study regarding the associations between measurements of psoas muscle, bone microarchitecture, and surgical outcomes is warranted.

Comparison of radiological and functional outcomes of conservative treatment with teriparatide and denosumab in thoracolumbar osteoporotic vertebral fracture

Teriparatide and denosumab, anti-osteoporosis medications with different mechanisms, have been widely used in the patients with osteoporotic vertebral fracture (OVF) considered as advanced osteoporosis. Teriparatide has been shown to enhance bone formation and fracture healing in OVF, but there are still no sufficient evidences discussing about the role of denosumab in newly developed OVF. In this study, we found the similar radiological deformation and functional outcomes of conservative treatment with teriparatide and denosumab in thoracolumbar (TL) OVF, and teriparatide showed a more frequent incidence of fracture union with paravertebral bone bridge formation compared to denosumab.

INTRODUCTION

Teriparatide and denosumab have been widely used to treat advanced osteoporosis and prevent subsequent fractures in patients with OVCF. Unlike teriparatide, which is considered to be effective in fracture healing, there is still no clear role and evidence for the effect of denosumab in acute OVCF. This study compared the radiological and functional outcomes of conservative treatment with teriparatide and denosumab in TL-OVF.

METHODS

This retrospective study enrolled 78 women with mean age of 74.69 ± 7.66 (60-92) years diagnosed as a TL-OVF with no neurological deficits. All patients were treated conservatively with teriparatide (34 of group T, once-daily 20 μg) or denosumab (44 of group D, once-6 months 60 mg) for 6 months. We evaluated the radiological deformation (kyphotic angle, segmental vertebral kyphotic angle, and compression ratio) and the incidence of fracture union with paravertebral bone bridge formation (FUPB) and functional outcomes using the visual analog scale (VAS) and Oswestry Disability Index (ODI) at 0, 3, and 6 months.

RESULTS

In the radiological deformation and functional outcomes, there were no significant differences at 0, 3, and 6 months between the two groups (P > 0.05). However, the incidence of FUPB at 6 months was higher in group T (20/34, 58.8%) compared to group D (11/44, 25.0%) (P = 0.004), and teriparatide was the most statistically significant factor for achieving FUPB (OR 4.486, P = 0.012) in multivariable logistic analysis.

CONCLUSIONS

Teriparatide and denosumab, despite of their different pharmacological mechanisms, showed similar radiological deformation and functional outcomes in the conservative treatment of TL-OVF. However, teriparatide showed a significantly higher incidence of fracture union with paravertebral bone bridge formation.

Current Strategies in Medical Management of the Geriatric Hip Fracture Patient

Orthogeriatric hip fractures have high morbidity and mortality rates. Modern management focuses on multidisciplinary collaboration for prompt surgical stabilization, early mobilization with multimodal pain control to avoid opioid consumption, and an enhanced recovery pathway. Despite these advances, postoperative complications and mortality rates remain higher than age-matched control subjects. The authors of this article represent the orthopaedic, anesthesia, and hospitalist medicine members of a multidisciplinary team at a single, Level 1 trauma center. Our goal was to provide an up-to-date comprehensive review of orthogeriatric hip fracture perioperative management from a multidisciplinary perspective that every orthopaedic surgeon should know.

Non-operative Treatment of Osteoporotic Thoracolumbar Extension-distraction Fracture Using Teriparatide in Elderly Female Patient with Severe Osteoporosis under Inoperable Condition: A Case Report

Vertebral extension-distraction fractures are a type of unstable fracture and require surgical stabilization with instrumentation. Unfortunately, in elderly patients with severe osteoporosis, poor bone quality can be related to postoperative pseudo-arthrosis and instability. Teriparatide is known as an effective anabolic agent for bone healing, union, and managing osteoporosis. In this report, we describe a rare case of extension-distraction thoracolumbar fractures in 86-year-old female patient with severe osteoporosis, which was treated conservatively. The patient was inoperable due to the presence of concomitant cardiopulmonary problems and the patients' old age. She had poor bone quality on bone mineral densitometry (-6.7, lumbar spine) but no neurologic deficits. As conservative treatment, bedrest and pain control were first performed for three weeks along with the use of teriparatide for 6-month and supplementation of calcium and vitamin D. Afterwards, sitting and standing with wearable orthoses were gradually implemented. After 1 year, the patient achieved bone fusion and was able to walk by herself, and there was radiological correction of the initial segmental lordotic curvature and disappearance of the intravertebral gap caused by the extension-distraction fracture.

The Roles of LncRNAs in Osteogenesis, Adipogenesis and Osteoporosis

BACKGROUND

Osteoporosis (OP) is the most common bone disease, which is listed by the World Health Organization (WHO) as the third major threat to life and health among the elderly. The etiology of OP is multifactorial, and its potential regulatory mechanism remains unclear. Long non-coding RNAs (LncRNAs) are the non-coding RNAs that are over 200 bases in the chain length. Increasing evidence indicates that LncRNAs are the important regulators of osteogenic and adipogenic differentiation, and the occurrence of OP is greatly related to the dysregulation of the bone marrow mesenchymal stem cells (BMSCs) differentiation lineage. Meanwhile, LncRNAs affect the occurrence and development of OP by regulating OP-related biological processes.

METHODS

In the review, we summarized and analyzed the latest findings of LncRNAs in the pathogenesis, diagnosis and related biological processes of OP. Relevant studies published in the last five years were retrieved and selected from the PubMed database using the keywords of LncRNA and OP.

RESULTS/CONCLUSION

The present study aimed to examine the underlying mechanisms and biological roles of LncRNAs in OP, as well as osteogenic and adipogenic differentiation. Our results contributed to providing new clues for the epigenetic regulation of OP, making LncRNAs the new targets for OP therapy.

Prostate cancer-secreted CCN3 uses the GSK3β and β-catenin pathways to enhance osteogenic factor levels in osteoblasts

Prostate cancer osteoblastic bone metastases are incurable and associated with chronic bone pain and a high mortality rate. Osteoclast-targeting drugs intended to prevent skeletal-related events associated with prostate cancer bone metastases do not prolong overall survival. Improved understanding of the bone-derived factors that contribute to prostate cancer osteoblastic bone metastases is required to design treatments that will improve morbidities and overall survival. Activated osteoblasts stimulate prostate cancer growth in bone. In this study, we report that prostate cancer conditioned medium (CM) promoted bone morphogenetic protein (BMP)-2, -4 and -7 production and the expression of osteogenic transcription factors Runx2 and osterix in osteoblasts. Treating the prostate cancer CM with antibody against CCN3 (nephroblastoma-overexpressed), a cysteine-rich protein that belongs to the CCN family, reduced all of these increases. Incubation of osteoblasts with CCN3 facilitated phosphorylation of GSK3β and β-catenin. GSK3β and β-catenin inhibitors or siRNAs all abolished CCN3-induced promotion of BMPs, Runx2 and osterix expression in osteoblasts. Our results indicate that prostate cancer-secreted CCN3 enhances BMP, Runx2 and osterix expression in osteoblasts via the GSK3β and β-catenin signaling pathways. This understanding of the role played by CCN3 in osteoblastic prostate bone metastasis may lead to more efficient targeted therapies.

Effects of Teriparatide on Treatment Outcomes in Osteoporotic Hip and Pelvic Bone Fractures: Meta-analysis and Systematic Review of Randomized Controlled Trials

The primary objective of this study was to evaluate randomized controlled trials (RCTs) that have reported the effects of teriparatide on bone-healing in osteoporotic hip and pelvic bone fractures to determine the efficacy of teriparatide in lowering the rate of treatment failure. A total of 2,809 studies were identified using a comprehensive literature search (MEDLINE [n=1,061], Embase [n=1,395], and Cochrane Library n=353]). Five RCTs were included in the final analysis. Treatment failure rates at the last follow-up of osteoporotic hip and pelvic bone fractures between the teriparatide and control groups was the primary outcome. Treatment failure was defined as non-union, varus collapse of the proximal fragment, perforation of the lag screw, and any revision in cases due to mechanical failure of the implant during the follow-up period. The number of treatment failures in the teriparatide and placebo groups were 11.0% (n=20 out of 181) and 17.6% (n=36 out of 205), respectively. Although the rate of treatment failure in the teriparatide group was lower than that in the control group, this difference was not significant (odds ratio, 0.81 [95% confidence interval, 0.42–1.53]; P=0.16; I²=42%). This meta-analysis did not identify any significant differences in the rate of treatment failure between the teriparatide and control groups at final follow-up. Based on these results, we believe that there is a lack of evidence to confirm efficacy of teriparatide in reducing treatment failures in osteoporotic hip and pelvic bone fractures.

Fracture-dislocation of L5 Combined with Multi-level Traumatic Spondylolisthesis of the Lower Lumbar Spine Treated via the Posterior-only Approach: A Case Report

Fracture-dislocation of the lower lumbar spine, which is commonly caused by high-impact trauma and can lead to instability in the spine, is relatively rare. Surgical treatment is indicated to restore spinal balance, weight-bearing ability, and decompression of the neural elements. There are various available surgical options, including the posterior-only or anterior-only approaches, or a combination of them. However, there is still no definite classification and treatment strategy for fracture-dislocation of the lower lumbar spine. In this report, we describe a 65-year-old man presenting cauda equina syndrome caused by a fracture-dislocation of L5 combined with multi-level traumatic spondylolisthesis of the lower lumbar spine. The patient was treated via the posterior-only approach with neural decompression and anterior reconstruction with posterior instrumentation. We discuss the reasons why the posterior-only approach was decided upon and several meaningful points during the surgery in detail.

Therapeutic Effect of Teriparatide for Osteoporotic Thoracolumbar Burst Fracture in Elderly Female Patients

Objective

Teriparatide is known as an effective anabolic agent not only for severe osteoporosis but also for bone healing and union. We explored the possibility of teriparatide as an alternative treatment option for osteoporotic thoracolumbar (TL) burst fracture.

Methods

This retrospective study enrolled 35 female patients with mean age of 73.77±6.71 years (61–88) diagnosed as osteoporotic TL burst fracture with ≥4 of thoracolumbar injury classification and severity (TLICS) score and no neurological deficits. All patients were treated by teriparatide only (12 of group A), teriparatide plus vertebroplasty (12 of group B), or surgical fixation with fusion (11 of group C), and followed up for 12 months. Radiological outcomes were evaluated using radiological parameters including kyphotic angle (KA), segmental vertebral kyphotic angle (SVKA), compression ratio (CR), and vertebral body height (anterior [AH], middle [MH], posterior [PH]). Functional outcomes were evaluated using visual analog scale (VAS) and Macnab classification (MC).

Results

There were no statistical significant differences in age, bone mineral density (-3.36±0.73), and TLICS score (4.34±0.48) among the three groups (p>0.05). Teriparatide was administered during 8.63±2.32 months in group A and B. In 12-month radiological outcomes, there were significant restoration in SVKA, CR, AH, and MH of group B and KA, SVKA, CR, AH, and MH of group C compared to group A with no radiological changes (p<0.05). All groups showed similar significant improvements in 12-month functional outcomes, although group B and C showed a better 1-month VAS, 1-month MC, 3-month MC compared to group A (p<0.05).

Conclusion

Non-surgical treatment with teriparatide showed similar 12-month functional outcomes compared to surgical fixation with fusion. The additional vertebroplasty to teriparatide and surgical fixation with fusion were more helpful to improve short-term functional outcomes with structural restoration compared to teriparatide only.

Pathogenesis and multidisciplinary management of medication-related osteonecrosis of the jaw

Medication-related osteonecrosis of the jaw (MRONJ) is a serious side effect of bone-modifying agents and inhibits angiogenesis agents. Although the pathogenesis of MRONJ is not entirely clear, multiple factors may be involved in specific microenvironments. The TGF-β1 signalling pathway may have a key role in the development of MRONJ. According to the clinical stage, multiple variables should be considered when selecting the most appropriate treatment. Therefore, the prevention and management of treatment of MRONJ should be conducted in patient-centred multidisciplinary team collaborative networks with oncologists, dentists and dental specialists. This would comprise a closed responsibility treatment loop with all benefits directed to the patient. Thus, in the present review, we aimed to summarise the pathogenesis, risk factors, imaging features, clinical staging, therapeutic methods, prevention and treatment strategies associated with MRONJ, which may provide a reference that can inform preventive strategies and improve the quality of life for patients in the future.

Preoperative bone health assessment and optimization in spine surgery

OBJECTIVE

The purpose of this investigation was to characterize the bone health in preoperative spine surgery patients. This information will provide a framework to understand the needs and methods for providing bone health optimization in elective spine surgery patients.

METHODS

A retrospective study of 104 patients undergoing bone health optimization was performed. Patients were selected based on risk factors identified by the surgeon and suspected compromised bone health. Evaluation included history and examination, laboratory investigations, and bone mineral density (BMD) at 3 sites (femoral neck, lumbar spine, and radius). Patients' bone status was classified using WHO criteria and expanded criteria recommended by the National Osteoporosis Foundation (NOF). The 10-year Fracture Risk Assessment Tool (FRAX) scores of the hip and major osteoporotic fracture (MOF) were calculated with and without femoral neck BMD, with spine BMD, and with the trabecular bone score (TBS). Antiresorptive and anabolic agents were provided in accordance with meeting NOF criteria for treatment of osteoporosis.

RESULTS

The mean patient age was 69.0 years, and 81% of patients were female. The mean historical height loss was 5.6 cm, and 54% of patients had a history of fracture. Secondary osteoporosis due to chronic renal failure, inflammatory arthritis, diabetes, and steroid use was common (51%). The mean 25-hydroxy vitamin D was 42.4 ng/ml and was normal in 81% of patients, with only 4 patients being deficient. The mean T-scores were -2.09 (SD 0.71) of the femoral neck, -0.54 (1.71) of the lumbar spine, and -1.65 (1.38) of the distal radius. These were significantly different. The 10-year FRAX MOF score was 20.7%, and that for hip fracture was 6.9% using the femoral neck BMD and was not significantly different without the use of BMD. The FRAX risk-adjusted score using the lumbar spine BMD and TBS was significantly lower than that for the hip. Osteoporosis was present in 32.1% according to WHO criteria compared with 81.6% according to NOF criteria. Antiresorptive medications were recommended in 31 patients and anabolic medications in 44 patients.

CONCLUSIONS

Surgeons can reliably identify patients with poor bone health by using simple criteria, including historical height loss, history of fracture, comorbidities associated with osteoporosis, analysis of available imaging, and calculation of FRAX score without BMD. High-risk patients should have BMD testing and bone health assessment. In patients with osteoporosis, a comprehensive preoperative bone health assessment is recommended and, if warranted, pharmacological treatment should be started.

New Strategies in Enhancing Spinal Fusion

The biologic steps involved in creating a bony fusion between adjacent segments of the spine are a complex and highly coordinated series of events. There have been significant advancements in bone grafts and bone graft substitutes in order to augment spinal fusion. While autologous bone grafting remains the gold standard, allograft bone grafting, synthetic bone graft substitutes, and bone graft enhancers are appropriate in certain clinical situations. This article provides an overview of the basic biology of spinal fusion and strategies for enhancing fusion through innovations in bone graft material.

MicroRNA-16, via FGF2 Regulation of the ERK/MAPK Pathway, Is Involved in the Magnesium-Promoted Osteogenic Differentiation of Mesenchymal Stem Cells

microRNAs (miRNAs) participate in the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). However, few reports have discussed the effect of miRNAs on the magnesium chloride (MgCl₂)-induced promotion of osteogenic differentiation of BMSCs, a process involved in the healing of bone tissue. As determined in the present investigation, MgCl₂ decreased miR-16 levels; increased levels of fibroblast growth factor 2 (FGF2), p-p38, and p-ERK; and promoted the osteogenic differentiation of BMSCs. Enhancement of miR-16 levels by an miR-16 mimic blocked these MgCl₂-induced changes. Moreover, luciferase reporter assays confirmed that miR-16 binds to the 3'UTR region of FGF2 mRNA. Down-regulation of FGF2 blocked the MgCl₂-induced increases of p-p38 and p-ERK and the promotion of the osteogenic differentiation of BMSCs. Furthermore, over-expression of miR-16 attenuated the MgCl₂-induced overproduction of p-p38 and p-ERK1/2 and the high levels of osteogenic differentiation, effects that were reversed by elevated expression of FGF2. In summary, the present findings provide a mechanism by which miR-16 regulates MgCl₂-induced promotion of osteogenic differentiation by targeting FGF2-mediated activation of the ERK/MAPK pathway.

Calvarial Versus Long Bone: Implications for Tailoring Skeletal Tissue Engineering

Tissue-engineered graft substitutes have shown great potential to treat large bone defects. While we usually assume that therapeutic approaches developed for appendicular bone healing could be similarly translated for application in craniofacial reconstruction and vice versa, this is not necessarily accurate. In addition to those more well-known healing-associated factors, such as age, lifestyle (e.g., nutrition and smoking), preexisting disease (e.g., diabetes), medication, and poor blood supply, the developmental origins and surrounding tissue of the wound sites can largely affect the fracture healing outcome as well as designed treatments. Therefore, the strategies developed for long bone fracture repair might not be suitable or directly applicable to skull bone repair. In this review, we discuss aspects of development, healing process, structure, and tissue engineering considerations between calvarial and long bones to assist in designing the tailored bone repair strategies. Impact Statement We summarized, in this review, the existing body of knowledge between long bone and calvarial bone with regard to their development and healing, tissue structure, and consideration of current tissue engineering strategies. By highlighting their similarities and differences, we propose that tailored tissue engineering strategies, such as scaffold features, growth factor usage, and the source of cells for tissue or region-specific bone repair, are necessary to ensure an optimized healing outcome.

Effects of Intermittent Administration of Parathyroid Hormone and Parathyroid Hormone-Related Protein on Fracture Healing: A Narrative Review of Animal and Human Studies

Intermittent administration of parathyroid hormone (PTH) stimulates skeletal remodeling and is a potent anabolic agent in bone. PTH‐related protein (PTHrP) is anabolic acting on the same PTH1 receptor and is in therapeutic use for osteoporosis. The body of literature for PTH actions in fracture healing is emerging with promising yet not entirely consistent results. The objective of this review was to perform a literature analysis to extract up‐to‐date knowledge on the effects of intermittent PTH and PTHrP therapy in bone fracture healing. A literature search of the PubMed database was performed. Clinical case studies and articles related to “regeneration,” “implant,” and “distraction osteogenesis” were excluded. A narrative review was performed to deliberate the therapeutic potential of intermittent PTH administration on fracture healing. A smaller number of studies centered on the use of PTHrP or a PTHrP analog were also reviewed. Animal studies clearly show that intermittent PTH therapy promotes fracture healing and revealed the strong therapeutic potential of PTH. Human subject studies were fewer and not as consistent as the animal studies yet provide insight into the potential of intermittent PTH administration on fracture healing. Differences in outcomes for animal and human studies appear to be attributed partly to variable doses, fracture sites, age, remodeling patterns, and bone architectures, although other factors are involved. Future studies to examine the dose, timing, and duration of PTH administration will be necessary to further delineate the therapeutic potential of PTH for fracture healing in humans. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

[Influence of specific osteoporosis drugs on fracture healing]

BACKGROUND

For the treatment of disturbed fracture healing, drugs could be given in addition to surgical procedures. Specific osteoporosis drugs affect the bone metabolism and are used to treat osteoporosis, particularly after a fragility fracture has occurred. Therefore, their use would be conceivable to improve a disturbed fracture healing.

OBJECTIVE

This article presents the available and upcoming specific osteoporosis drugs and investigates whether these substances affect fracture healing in the context of osteoporosis. Furthermore, it is discussed whether disturbed fracture healing can be improved by the use of these substances.

MATERIAL AND METHODS

A literature search (PubMed) was conducted using key terms. Preclinical studies, clinical studies, reviews and meta-analyses were considered in order to present the current knowledge in a clinically relevant context.

RESULTS

Preclinical and clinical studies show that specific osteoporosis drugs have no relevant negative impact on the healing of fragility fractures. A tendency to improve a disturbed fracture healing was attributed to bone anabolic substances; however, studies are inconsistent and there is no approval for this application.

CONCLUSION

Following a fragility fracture, osteoporosis should be diagnosed according to the guidelines and, if necessary, treated with specific osteoporosis drugs, since in principle they do not impair fracture healing but significantly reduce the risk of subsequent fractures. Approval to improve fracture healing requires further investigations.

Bone Health Optimization: Beyond Own the Bone: AOA Critical Issues

Worldwide, osteoporosis management is in crisis because of inadequate delivery of care, competing guidelines, and confusing recommendations. Additionally, patients are not readily accepting the diagnosis of poor bone health and often are noncompliant with treatment recommendations. Secondary fracture prevention, through a program such as Own the Bone, has improved the diagnosis and medical management after a fragility fracture. In patients who undergo elective orthopaedic procedures, osteoporosis is common and adversely affects outcomes. Bone health optimization is the process of bone status assessment, identification and correction of metabolic deficits, and initiation of treatment, when appropriate, for skeletal structural deficits. The principles of bone health optimization are similar to those of secondary fracture prevention and can be initiated by all orthopaedic surgeons. Patients who are ≥50 years of age should be assessed for osteoporosis risk and, if they are in a high-risk group, bone density should be measured. All patients should be counseled to consume adequate vitamin D and calcium and to discontinue use of any toxins (e.g., tobacco products and excessive alcohol consumption). Patients who meet the criteria for pharmaceutical therapy for osteoporosis should consider delaying surgery for a minimum of 3 months, if feasible, and begin medication treatment. Orthopaedic surgeons need to assume a greater role in the care of bone health for our patients.

CCN3 Facilitates Runx2 and Osterix Expression by Inhibiting miR-608 through PI3K/Akt Signaling in Osteoblasts

CCN3, otherwise known as the nephroblastoma overexpressed (NOV) protein, is a cysteine-rich protein that belongs to the CCN family and regulates several cellular functions. Osteoblasts are major bone-forming cells that undergo proliferation, mineralization, renewal, and repair during the bone formation process. We have previously reported that CCN3 increases bone morphogenetic protein 4 (BMP-4) production and bone mineralization in osteoblasts, although the role of CCN3 remains unclear with regard to osteogenic transcription factors (runt-related transcription factor 2 (Runx2) and osterix). Here, we used alizarin red-S and alkaline phosphatase staining to show that CCN3 enhances osteoblast differentiation. Stimulation of osteoblasts with CCN3 increases expression of osteogenic factors such as BMPs, Runx2, and osterix. Moreover, we found that the inhibition of miR-608 expression is involved in the effects of CCN3 and that incubation of osteoblasts with CCN3 promotes focal adhesion kinase (FAK) and Akt phosphorylation. Our results indicate that CCN3 promotes the expression of Runx2 and osterix in osteoblasts by inhibiting miR-608 expression via the FAK and Akt signaling pathways.

Preoperative Assessment of Bone Quality in Spine Deformity Surgery: Correlation With Clinical Practice and Published Recommendations

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The goals of this study were to (A) evaluate preoperative bone quality assessment and intervention practice over time and (B) review the current evidence for bone evaluation in spine fusion surgery.

SUMMARY OF BACKGROUND DATA

Deformity spine surgery has demonstrated improved quality of life in patients; however, its cost has made it controversial. If preoperative bone quality can be optimized then potentially these treatments could be more durable; however, at present, no clinical practice guidelines have been published by professional spine surgical organizations.

METHODS

A retrospective cohort review was performed on patients who underwent a minimum five-level primary or revision fusion. Preoperative bone quality metrics were evaluated over time from 2012 to 2017 to find potential trends. Subgroup analysis was conducted based on age, sex, preoperative diagnosis, and spine fusion region.

RESULTS

Patient characteristics including preoperative rates of pseudarthrosis and junctional failure did not change. An increasing trend of physician bone health documentation was noted (P = 0.045) but changes in other metrics were not significant. A sex bias favored females who had higher rates of preoperative DXA studies (P = 0.001), Vitamin D 25-OH serum labs (P = 0.005), Vitamin D supplementation (P = 0.022), calcium supplementation (P < 0.001), antiresorptive therapy (P = 0.016), and surgeon clinical documentation of bone health (P = 0.008) compared with men.

CONCLUSION

Our spine surgeons have increased documentation of bone health discussions but this has not affected bone quality interventions. A discrepancy exists favoring females over males in nearly all preoperative bone quality assessment metrics. Preoperative vitamin D level and BMD assessment should be considered in patients undergoing long fusion constructs; however, the data for bone anabolic and resorptive agents have less support. Clinical practice guidelines on preoperative bone quality assessment spine patients should be defined.

LEVEL OF EVIDENCE

4.

Current and emerging osteoporosis pharmacotherapy for women: state of the art therapies for preventing bone loss

INTRODUCTION

Pharmacological options to address the imbalance between bone resorption and accrual in osteoporosis include anti-resorptive and osteoanabolic agents. Unique biologic pathways such as the Wnt/β-catenin pathway have been targeted in the quest for new emerging therapeutic strategies.

AREAS COVERED

This review provides an overview of existing pharmacotherapy for osteoporosis in women and explore state-of-the-art and emerging therapies to prevent bone loss, with an emphasis on the mechanism of action, indications and side effects.

EXPERT OPINION

Bisphosphonates appear to be a reliable and cost-effective option, whereas denosumab has introduced a simpler dosing regimen and may achieve a linear increase in bone mineral density (BMD) with no plateau being observed, along with continuous anti-fracture efficacy. Abaloparatide, a parathyroid-hormone-related peptide (PTHrP)-analogue, approved by the FDA in April 2017, constitutes the first new anabolic osteoporosis drug in the US for nearly 15 years and has also proven its anti-fracture efficacy. Romosozumab, a sclerostin inhibitor, which induces bone formation and suppresses bone resorption, has also been developed and shown a significant reduction in fracture incidence; however, concerns have arisen with regard to increased cardiovascular risk.

Long noncoding RNAs: a missing link in osteoporosis

Osteoporosis is a systemic disease that results in loss of bone density and increased fracture risk, particularly in the vertebrae and the hip. This condition and associated morbidity and mortality increase with population ageing. Long noncoding (lnc) RNAs are transcripts longer than 200 nucleotides that are not translated into proteins, but play important regulatory roles in transcriptional and post-transcriptional regulation. Their contribution to disease onset and development is increasingly recognized. Herein, we present an integrative revision on the studies that implicate lncRNAs in osteoporosis and that support their potential use as therapeutic tools. Firstly, current evidence on lncRNAs involvement in cellular and molecular mechanisms linked to osteoporosis and its major complication, fragility fractures, is reviewed. We analyze evidence of their roles in osteogenesis, osteoclastogenesis, and bone fracture healing events from human and animal model studies. Secondly, the potential of lncRNAs alterations at genetic and transcriptomic level are discussed as osteoporosis risk factors and as new circulating biomarkers for diagnosis. Finally, we conclude debating the possibilities, persisting difficulties, and future prospects of using lncRNAs in the treatment of osteoporosis.