Rationale : Osteoporosis is a severe bone disorder that is a threat to our aging population. Excessive osteoclast formation and bone resorption lead to changes in trabecular bone volume and architecture, leaving the bones vulnerable to fracture. Therapeutic approaches of inhibiting osteoclastogenesis and bone resorption have been proven to be an efficient approach to prevent osteoporosis. In our study, we have demonstrated for the first time that Loureirin B (LrB) inhibits ovariectomized osteoporosis and explored its underlying mechanisms of action in vitro . Methods : We examined the effects of LrB on RANKL-induced osteoclast differentiation and bone resorption, and its impacts on RANKL-induced NFATc1 activation, calcium oscillations and reactive oxygen species (ROS) production in osteoclasts in vitro . We assessed the in vivo efficacy of LrB using an ovariectomy (OVX)-induced osteoporosis model, which was analyzed using micro-computed tomography (micro-CT) and bone histomorphometry. Results : We found that LrB represses osteoclastogenesis, bone resorption, F-actin belts formation, osteoclast specific gene expressions, ROS activity and calcium oscillations through preventing NFATc1 translocation and expression as well as affecting MAPK-NFAT signaling pathways in vitro . Our in vivo study indicated that LrB prevents OVX-induced osteoporosis and preserves bone volume by repressing osteoclast activity and function. Conclusions : Our findings confirm that LrB can attenuate osteoclast formation and OVX-induced osteoporosis. This novel and exciting discovery could pave the way for the development of LrB as a potential therapeutic treatment for osteoporosis.

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Background Intra-articular injections containing a corticosteroid are used frequently, and periprosthetic joint infection is a serious complication after total joint arthroplasty. There is debate regarding whether intraarticular corticosteroid injections before arthroplasty increase periprosthetic joint infection after surgery. Questions/purposes (1) Does a previous intra-articular corticosteroid injection increase the odds of infection after subsequent hip or knee arthroplasty? (2) Does this risk vary based on how soon before the arthroplasty (such as less than 3 months before surgery) the injection is administered?Methods Using the PubMed, Embase, Cochrane Library, and Web of Science databases from inception to July 2021, we searched for comparative studies in English on patients who received intra-articular corticosteroid injections before arthroplasty and that tracked the frequency of infection after arthroplasty. We extracted data on the risk of infection after subsequent joint arthroplasty. The keywords included "corticosteroid," "steroid," "arthroplasty," "knee replacement," and "hip replacement." Eleven retrospective, comparative studies from four countries were included, of which 10 reported the specific diagnosis criteria and oneThe institution of one or more of the authors (QZ) has received, during the study period, funding from the Natural Science Foundation of Guangdong (2015A030313353). The institution of one or more of the authors (CZ) has received, during the study period, funding from the Research Project of Innovating to Strengthen the First Hospital of Guangzhou University of Chinese Medicine (2019IIT06). Each author certifies that there are no funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article related to the author or any immediate family members. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.

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Osteopontin (OPN) is an extracellular matrix protein that is expressed in bone cells such as osteoblast and osteocytes and associated with bone turnover and bone mineral density (BMD) in postmenopausal women. Here, we aimed to investigate the relationship between circulating OPN levels and BMD in postmenopausal women in Southern China. A total of 362 postmenopausal women were consecutively recruited into this study from 2011-2013. Serum levels of OPN, receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL), and bone turnover markers were analyzed. BMD was measured by dual energy X-ray absorptiometry. Osteoporosis and osteopenia were diagnosed according to the World Health Organization criteria. Serum OPN levels were remarkably higher in the osteoporotic group than those in the osteopenic and normal groups (all p < 0.001). The cut-off value of OPN for diagnosing postmenopausal osteoporosis was 10.1 ng/mL, which had a sensitivity of 89.5%, a specificity of 70.8%, and an area under curve of 0.953. Serum OPN was negatively correlated with parathyroid hormone (PTH), lumbar spine BMD, and femoral neck BMD (r = -0.25, p = 0.004; r = -0.66, p < 0.001; r = -0.28, p = 0.001; respectively) and positively associated with type I procollagen amino-terminal propeptide (PINP), carboxy-terminal cross-linking telopeptide of type I collagen (CTX), and RANKL (r = 0.20, p = 0.020; r = 0.17, p = 0.036; r = 0.19, p = 0.028, respectively) in the osteoporotic group. In multiple regression analyses, lumbar spine BMD, PTH and RANKL were the predictors for serum OPN levels. In conclusion, OPN serum levels are negatively related to BMD and positively correlated with bone turnover levels in this group of Chinese postmenopausal women.