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Background: Biomaterials used in fracture healing hold a significant place in orthopedics. This study aimed to develop biomaterials coated with hydroxyapatite (HA), boric acid (BA), and magnesium (Mg) and investigate their effects on fracture healing., Methods: Sixty female Wistar Albino rats were included in the study. The subjects were randomized into five groups. Cytotoxicity tests were performed on HA, BA, and Mg, and cell viability rates were calculated. Coatings were applied to Kirschner (K) wires at determined ratios. Group I was the control group with a steel K wire, Group II used HA-coated K wires, Group III used HA + BA-coated K wires, Group IV used HA + BA + Mg-coated K wires, and Group V used HA + Mg-coated K wires. A fracture was induced in the right femur of the subjects, followed by fixation with intramedullary K wires. The subjects were randomly divided into equal numbers and sacrificed at 6 and 12 weeks. Radiological and histopathological evaluations were performed., Results: In direct cytotoxicity tests, the highest viability rate was observed in Group IV, while in indirect cytotoxicity tests, it was highest in Group II. In radiological evaluation at the 6th week, the highest scores were in Groups IV and V, while the lowest was in Group III. At the 12th week, the highest scores were in Groups II and V, while the lowest was in Group I. No significant differences were found between the groups (p = 0.837, p = 0.0479). In histopathological evaluation, a significant difference was observed between the groups (p < 0.001), with the highest scores in Group V. A correlation was found between the radiological and histopathological scores (p < 0.001, r = 0.438)., Conclusion: It was found that HA + Mg significantly improved histological outcomes in fracture healing. Good histological results can be achieved with the use of Mg-containing implants in both early and late-stage fracture healing. Coating the biomaterials used in fracture fixation with Mg may lead to positive outcomes in fracture healing., Competing Interests: Declarations Ethics approval and consent to participate The study, referenced as AKUHADYEK-25-21, received ethical approval from the Afyon Kocatepe University Local Animal Experiments Ethics Committee (HADYEK) under decision number 49533702/30. The study was conducted at Afyon Kocatepe University Animal Husbandry and Research Experimental Animals Center. Consent for publication Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Nanotherapeutic techniques are becoming increasingly important in the treatment of bone disorders owing to their targeted drug delivery. This study formulates zein nano coop composites containing chimeric antioxidants (ascorbic acid, luteolin, resveratrol, and coenzyme Q) (AZN) and evaluates its application in bone regeneration using osteoblasts and a Zebrafish osteoporosis model. In vitro experiments with human osteoblast-like MG63 cells showed enhancement of bone mineralization and regeneration. It further exhibited high biocompatibility in Zebrafish larvae, with increased calcium/phosphorus deposition and upregulation of osteogenic genes. The study has unequivocally demonstrated the potential of AZN in bone regeneration and fracture healing in both normal and osteoporosis models, underscoring the significance of this research. Further investigations using higher animal models are warranted to expand on these findings. The impact of this research seems far-reaching, with the possible development of new, effective, and safe treatment options for osteoporosis, addressing the limitations of the currently available treatments.

Objectives: To investigate the effect of tranexamic acid (TXA) through in vitro culture of primary human osteoblasts (HOB) and in vivo using an operative rat femur fracture model. It was hypothesized that there would not be any effect on fracture healing in both studies., Methods: Primary HOBs were exposed to varying concentrations of TXA over different time periods. Cells were assessed for viability, metabolism, and mineralization. For the in vivo model, fractures were created in the femora of adult rats, exposed to either TXA or saline, and then assessed for healing at different time points. A modified radiographic union score for tibia was used to evaluate radiographs, callus mineralization was assessed with microcomputed tomography, and biomechanical tests were performed., Results: Overall, HOB viability and metabolism decreased as TXA concentration and exposure time increased. However, at concentrations below 56.44 mg/mL, HOB viability was not affected. Similarly, mineralization also decreased as TXA concentration and exposure time increased. In both groups, in vivo results demonstrated increasing radiographic healing, callus mineralization, and biomechanical strength as a function of time. There was a trend for increased healing in the TXA group at 6 weeks after fracture; however, the difference compared with untreated animals was not statistically significant., Conclusions: Although a degradation of HOB viability and metabolism occurred with increased TXA concentrations and exposure times, clinically relevant concentrations do not adversely affect HOB viability, metabolism, or mineralization. In addition, there were no noticeable adverse effects of TXA administration in the in vivo model., Competing Interests: The authors report no conflict of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Infected fracture healing is a complicated process that includes intricate interactions at the cellular and molecular levels. In addition to angiogenesis and osteogenesis, the significance of neurogenesis in fracture healing has also been recognized in recent years. Here, a nanocomposite hydrogel containing pH-responsive zinc-gallium-humic acids (HAs) nanoparticles is developed. Through the timed release of Zn 2+ , Ga 3+ , and HAs, the hydrogel exhibits potent antibacterial effects and promotes angiogenesis, osteogenesis, and neurogenesis. The enhanced neurogenesis further promotes angiogenesis and osteogenesis, forming a mutually supportive angiogenesis-osteogenesis-neurogenesis cycle at the fracture site. The hydrogel achieves rapid infected fracture healing and improves tissue regeneration in mice. This study proposes a comprehensive treatment approach that combines antibacterial effects with the regulation of tissue regeneration to improve infected fracture healing., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Objectives: Previous evidence suggests that bisphosphonates (BPs) may lower the risk of recurrent fractures and enhance functional recovery in patients with fractures. However, there has been controversy regarding the optimal timing of treatment initiation for patients with fragility fractures. We conducted a meta-analysis to evaluate the available evidence on the use of BPs during the perioperative period and compared it to both non-perioperative periods and non-usage., Methods: Electronic searches were performed using PubMed, EMBASE, Web of Science and the Cochrane Library published before February 2023, without any language restrictions. The primary outcomes included fracture healing rate, healing time, and new fractures. We also examined a wide range of secondary outcomes. Random effects meta-analysis was used., Results: A total of 19 clinical trials involving 2543 patients were included in this meta-analysis. When comparing patients with non-perioperative BPs use in 4-6 weeks and approximately 10-12 weeks post-surgically, the overall risk ratios (RRs) of perioperative BPs use for healing rate were 1.06 (95% CI: 0.81, 1.38, p=0.69) and 1.02 (95% CI: 0.94, 1.11, p=0.65), respectively, suggesting no difference in healing rate between perioperative and non-perioperative BP initiation. For healing time, the overall mean difference between perioperative and non-perioperative periods was -0.19 week (95% CI: -1.03, 0.64, p=0.65) at approximately 10-12 weeks, indicating no significant impact of perioperative BP initiation on healing time. In terms of new fractures, the overall RR with BP use was 0.35 (95% CI: 0.17-0.73, p=0.005), when compared to patients without BPs use. This suggests a protective impact of BP use against new fractures compared to patients without BP use. Perioperative BP use was associated with a markedly higher likelihood of having adverse experiences, including fever (RR: 23.78, 95% CI: 8.29, 68.21, p< 0.001), arthralgia (RR: 10.20, 95% CI: 2.41, 43.16, p=0.002), and myalgia (RR: 9.42, 95% CI: 2.54, 34.87, p< 0.001), compared with non-BPs use., Conclusions: Treatment with BP during the perioperative period does not affect the healing process and has positive effects on therapy for patients with fragility fractures. These compelling findings underscore the potential efficacy of BP use during the perioperative period as a viable treatment option for patients with fragility fractures., (© 2024. The Author(s).)

Carpal navicular fractures are the most common carpal fractures. This study intends to explore the specific mechanism of Zoledronic Acid (ZA) in carpal navicular fracture healing via long non-coding RNA (lncRNA) growth arrest specificity 5 (GAS5) to mediate microRNA (miR)-29a-3p. A fractured rat model was constructed. Two weeks later, a subcutaneous injection of systemic ZA was implemented, and an injection of plasmid vectors interfered with GAS5 or miR-29a-3p expression was performed on the fracture site. Osteocalcin (OCN) and bone morphogenetic protein-2 (BMP-2) were determined, as well as serum levels of alkaline phosphatase (ALP), osteopontin (OPN) and osteoprotegerin (OPG) and bone mineral density. MC3T3-E1 cells were transfected with plasmid vectors interfering with GAS5 or miR-29a-3p, and cell proliferation and apoptosis were analyzed. GAS5 and miR-29a-3p expression in fractured rats was tested, together with their binding relationship. ZA promoted OCN and BMP-2 expression, increased bone mineral density and serum levels of ALP, OPN and OPG in fractured rats. GAS5 was upregulated and miR-29a-3p was down-regulated in fractured rats. Downregulation of GAS5 or upregulation of miR-29a-3p further promoted bone healing in fractured rats. GAS5 targets miR-29a-3p, and down-regulation of miR-29a-3p can reverse the effect of down-regulation of GAS5 on bone healing in fractured rats. ZA promoted the proliferation of MC3T3-E1 cells and inhibited apoptosis by regulating the GAS5/miR-29a-3p axis. ZA regulates miR-29a-3p expression by down-regulating GAS5 to promote carpal navicular fracture healing, promote MC3T3-E1 cell proliferation, and inhibit cell apoptosis., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Fracture healing or nonunion refers to a process in which many factors interact. In this study, we aimed to evaluate the radiological, histological, and biomechanical effects of phenyramidol and diclofenac, which are frequently used to treat post-fracture ture pain worldwide, on fracture healing and nonunion in a rat femur fracture model., Methods: In this study, 72 male Wistar-Albino rats aged 2-3 months and weighing 250 ± 30 g were divided into 4 main groups. The rats were divided into 12 subgroups according to the early, middle, and late periods. A fracture model was created in rat femurs, and surgical fixation was performed. Postoperative analgesic treatment protocols included phenyramidol, diclofenac, phenyramidol + diclofenac, and the control group. The rats were sacrificed on the fifteenth, thirtieth, and forty-fifth days and were evaluated radiologically, histopathologically, and biomechanically., Results: Scoring was conducted independently by 2 orthopedists not involved in the study. When the results were analyzed statistically, no statistically significant difference was observed between the fifteenth and thirtieth day radiology score values of the control, diclofenac, phenyramidol, and Phenyramidol + diclofenac groups ( p > 0.05), but there was a statistically significant difference ( p < 0.05) between the forty-fifth day radiology score values of the control, diclofenac, phenyramidol, and phenyramidol + diclofenac groups., Conclusions: Our study shows that the use of diclofenac or phenyramidol alone negatively affects postoperative fracture healing. However, this effect was less pronounced in the combined treatment group. Histologic examination revealed that neither treatment had a significant effect on healing. There were statistical differences in biomechanical and radiologic properties between the phenyramidol and diclofenac groups; in particular, the diclofenac group had lower biomechanical properties., Competing Interests: CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported., (Copyright © 2024 by The Korean Orthopaedic Association.)

Introduction: Recombinant human Bone morphogenetic proteins have been used for the treatment of nonunions with promising results. We have been investigating both experimentally and clinically the efficacy of the rhBMP-2 with the macro / micro-porous hydroxyapatite carrier granules on the potency on the reconstruction of long bone defect. The purpose of this study was to prospectively evaluate the efficacy and safety of this specific rhBMP-2 with HA carrier granules mixed with autologous cancellous bone in patients with nonunion and bone defect resulted from the fracture related infection., Materials and Methods: This was a retrospective review of a prospective cohort at a university hospital. Patients diagnosed with nonunion under the definition of the United States Food and Drug Administration with bone defect after long bone fractures were enrolled from January 2020 to February 2021. We included patients with atrophic and oligotrophic nonunion, and hypertrophic nonunion with malalignment that needed to be corrected. The other patient group was consisted of segmental bone defect resulted from FRI. The maximum amount of rhBMP-2 allowed in this clinical study was 6 mg and was added to autologous bone at a 1:1 ratio. Autologous bone was added to the mixture if the volume of mixed graft was insufficient to fill the bone defect. Patients were followed 3, 6, and 12 months post-operatively. Each visit, a radiograph was taken for assessment. Visual analog scale (VAS), questionnaire for quality of life (SF-12 physical component summary [PCS], mental component summary [MCS]), and weight-bearing status were collected for functional outcome assessment. Drug safety was assessed by examining BMP-2 antibodies., Results: Of the 24 enrolled patients (mean age: 57 years), 15 (62.5 %), 2 (8.33 %), and 7 (29.17 %) presented atrophic nonunion, hypertrophic nonunion with deformity, and bone defect after fracture related infection, respectively. Thirteen patients had nonunion in the femur, 9 in the tibia, and 1 in the humerus and radius. The average amount of harvested autologous bone was 9.25 g and 4.96 mg of rhBMP-2. All 24 patients achieved union after 1-year follow up. The union rate was 95.83 % and 100 % at 6 and 12 months postoperatively, respectively. Preoperative SF-12 PCS (mean: 34.71) improved at 6 and 12 months postoperatively, respectively. Preoperative SF-12 MCS (mean: 42.89) improved 12 months postoperatively (49.13, p = 0.0338). Change of VAS was statistically significant 3 months postoperatively (p = 0.0012). No adverse effects or development of BMP-2 antibodies were observed., Conclusion: BMP-2 combined with autogenous bone resulted in excellent radiographical and functional outcomes in a relatively small prospective series of patients with nonunion and bone defect, without adverse effects. Further investigations are necessary to support our finding and optimize treatment strategies in nonunion patients., Competing Interests: Declaration of competing interest None., (Copyright © 2024. Published by Elsevier Ltd.)

Fracture healing is a process in which many factors interact. In addition to many treatments, physical and biological therapy methods that affect different steps of this process, there are many biological and chemical agents that cause fracture union delay. Although the number of studies on fracture healing is increasing day by day, the mechanism of fracture healing, which is not fully understood, still attracts the attention of all researchers. In this study, we aimed to investigate the effects of favipiravir and hydroxychloroquine used in the treatment of COVID-19. In this study, 48 male Wistar rats weighing 300 ± 50 g were used. Each group was divided into eight subgroups of six rats each to be sacrificed at the 2nd and 4th weeks and evaluated radiologically and histologically. Favipiravir (group 1), hydroxychloroquine (group 2), favipiravir + hydroxychloroquine (group 3), and random control (group 4) were used. A statistically significant difference was observed between the 15th day histological scoring averages of the groups (p < 0.05). Although there was no statistically significant difference between the 15th day radiological score distributions of the groups (p > 0.05), we obtained different results in terms of complete bone union distributions and radiological images of the fracture line. Although favipiravir has a negative effect on fracture union in the early period, favipiravir may have a positive effect on fracture union in the late period. We did not find any effect of hydroxychloroquine on fracture union., (© 2024. The Author(s).)

Osteoporosis easily causes delayed fracture union, even non-union. It has been demonstrated that dehydroepiandrosterone (DHEA) supplementation can increase estrogen levels and improve bone mineral density (BMD) in the elderly, while the role of DHEA on fracture healing remains unknown. This study aimed to elucidate the impact of DHEA supplementation on osteoporotic fracture healing. Seventy-two female Sprague-Dawley rats were used. Forty-eight rats received ovariectomy (OVX), and the remaining rats received a sham OVX operation (sham group). A right transverse femoral osteotomy was performed in all rats at 12 weeks post-OVX. OVX rats were randomly allocated into 2 groups (n = 24 in each group): (i) ovariectomized rats (control group) and (ii) ovariectomized rats treated with DHEA (DHEA group, 5 mg/kg/day). The DHEA supplementation was initiated on the first day post-fracture for 3, 6, and 12 weeks. Fracture healing was evaluated by radiography, histology, biomechanical analysis, and dual-energy X-ray absorptiometry (DEXA). Serum biomarkers were analyzed using enzyme-linked immunosorbent assay (ELISA). At 3 and 6 weeks, radiographs revealed reduced calluses formation and lower radiographic scores in the control group than in other groups. The sham and DHEA groups showed higher BMD and bone mineral content (BMC) at the fracture site than the control group after fracture. Histological analysis revealed the fracture callus was remodeled better in the sham and DHEA groups than in the control group. At the early phase of healing, DHEA supplementation increased osteoblast number, callus area, and cartilage area than the control group. An increased bone area was observed in the DHEA group than in the control group at the late phase of healing. Additionally, improved biomechanical characteristics were observed in both the sham and DHEA groups than those in the control group post-fracture. ELISA showed higher levels of insulin-like growth factor-1 (IGF-1) and 17β-estradiol (E2) in the DHEA group than in the control group post-fracture. Furthermore, the DHEA group exhibited significantly elevated alkaline phosphatase (ALP) and osteocalcin (OC) levels compared to the control group at 6 and 12 weeks. The DHEA group and the control group did not exhibit a notable difference in TRAP-5b levels. The present study demonstrated that the DHEA treatment has a favorable impact on osteoporotic fracture healing by enhancing callus formation, consolidation, and strength in the OVX rats., Competing Interests: Declaration of competing interest All authors declare that they have no conflict of interest that might be perceived as influencing the author's objectivity., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Musculoskeletal traumatic injuries (MTI) involve soft tissue lesions adjacent to a bone fracture leading to fibrous nonunion. The impact of MTI on the inflammatory response to fracture and on the immunomodulation of skeletal stem/progenitor cells (SSPCs) remains unknown. Here, we used single-nucleus transcriptomic analyses to describe the immune cell dynamics after bone fracture and identified distinct macrophage subsets with successive pro-inflammatory, pro-repair and anti-inflammatory profiles. Concurrently, SSPCs transition via a pro- and anti-inflammatory fibrogenic phase of differentiation prior to osteochondrogenic differentiation. In a preclinical MTI mouse model, the injury response of immune cells and SSPCs is disrupted leading to a prolonged pro-inflammatory phase and delayed resolution of inflammation. Macrophage depletion improves bone regeneration in MTI demonstrating macrophage involvement in fibrous nonunion. Finally, pharmacological inhibition of macrophages using the CSF1R inhibitor Pexidartinib ameliorates healing. These findings reveal the coordinated immune response of macrophages and skeletal stem/progenitor cells as a driver of bone healing and as a primary target for the treatment of trauma-associated fibrosis., (© 2024. The Author(s).)

The process of skeletal regeneration initiated by stem cells following injury, especially in fractures, is significantly impaired by aging and adverse factors. Nicotinamide mononucleotide (NMN), a critical endogenous precursor of nicotinamide adenine dinucleotide (NAD), has garnered extensive attention for its multifaceted regulatory functions in living organisms and its wide-ranging therapeutic potential. However, whether NMN contributes to trauma-induced skeletal regeneration remains unclear. Methods : The transverse femoral shaft fracture model was employed to evaluate the potential advantages of NMN administration for overall repair during the initial fracture stages in male mice through micro-CT analysis, histochemistry, and biomechanical testing. The pro-proliferative function of NMN on skeletal stem cells (SSCs) was investigated through flow cytometry, qRT-PCR, NAD content measurement, and cell proliferation assay. Results : In this study, we observed that the administration of NMN during the initial phase of fracture in mice led to a larger callus and corresponding improvement in micro-CT parameters. NMN enhances the cartilaginous component of the callus by elevating the NAD content, consequently accelerating subsequent endochondral ossification and the fracture healing process. Subsequent analyses elucidated that NMN was beneficial in promoting the expansion of diverse stem cells in vivo and in vitro potentially via modulation of the Notch signaling pathway. Moreover, the depletion of macrophages profoundly obstructs the proliferation of SSCs. Conclusion : Our discoveries provide a potential strategy for enhancing fracture healing through stimulation of callus SSC proliferation at an early stage, shedding light on the translational value of NMN as an enhancer for skeletal regeneration and highlighting the pivotal role of macrophage-stem cell interactions in governing the regenerative influence of NMN on stem cells., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Introduction: Nonsteroidal anti-inflammatory drugs (NSAIDs) may potentially delay or cause non-union of fractures by inhibiting prostaglandin synthesis. However, studies have shown conflicting results. This systematic review and meta-analysis aim to synthesize current evidence on the potential influence of NSAIDs on bone healing., Methods: We conducted a comprehensive search of PubMed, Embase, and Cochrane CENTRAL databases for studies published up to 25 July 2023. Specific keywords included "NSAID," "nonsteroidal anti-inflammatory drug," "cyclooxygenase-2 inhibitor," "bone healing," "non-union," "pseudoarthrosis," "delayed union," and "atrophic bone." Eligible studies included prospective, retrospective, and case-controlled studies assessing the correlation between NSAID use and bone healing outcomes. The leave-one-out approach was used to test the robustness of the meta-analysis results., Results: A total of 20 studies with 523,240 patients were included in the analysis. The mean patient age ranged from 6.7 to 77.0 years, with follow-up durations from 3 to 67 months. The meta-analysis revealed no significant difference in non-union or delayed union between NSAID users and non-users [pooled adjusted odds ratio (OR) = 1.11; 95% confidence interval (CI): 0.99-1.23]. Initial analysis identified a significant association between NSAID usage and an increased risk of reoperation, but this association became insignificant upon sensitivity analysis (crude OR = 1.42; 95% CI: 0.88-2.28)., Discussion: NSAIDs may have a minimal impact on non-union or delayed union risks. However, caution is advised due to the limited number of studies and the absence of a specific focus on NSAID types and dosages. Further research is necessary to better understand the implications of NSAID use on bone healing., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Chuang, Yang, Tsai and Huang.)

Purpose: We investigated the potential efficacy of abaloparatide (Abalo) and zoledronate (ZA) combination therapy for accelerating femoral union in a rat osteotomy model. Methods: Nine-week-old male Sprague-Dawley rats were randomly divided into four groups ( n = 14 per group): control, abaloparatide (Abalo, 30 μg/kg via subcutaneous injection [s.c.] 5 times per week for 6 weeks), zoledronate (ZA; 0.1 mg/kg via s.c., single dose), and Abalo + ZA. Rats were then subjected to unilateral osteotomy of the femoral shaft, followed by osteosynthesis with intramedullary nailing to establish bone healing models. At 2 and 4 weeks after osteotomy, both femurs were removed from seven rats per group for soft X-ray imaging to evaluate bone union and microcomputed tomography (micro-CT) for bone morphometric evaluation. Blood samples were collected from all rats every 2 week starting 6 weeks pre- to 4 weeks postosteotomy. Toluidine blue staining was used for histopathological evaluation of the undecalcified specimens. Results: Soft X-ray imaging revealed accelerated callus formation, callus maturation, and fracture line closure in Abalo and Abalo + ZA groups compared to ZA and control groups. Micro-CT demonstrated greater cortical bone and trabecular bone to total volume ratios in contralateral (left) femurs of the Abalo + ZA group compared to the Abalo group. Both trabecular and cortical bone mineral densities were also greater in contralateral femurs of the Abalo + ZA group compared to Abalo and ZA groups. Conclusion: These findings suggest substantial additive or synergistic efficacy of abaloparatide plus zoledronate combination therapy for accelerating bone healing following osteotomy and for maintaining normal bone health., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Osteoporotic fractures seriously affect the quality of life of the elderly. Panax notoginseng saponins (PNS) have the potential function of preventing osteoporosis. The Phosphatidylinositol 3-kinase (PI3K)/protein kinase (AKT)/mammalian target of rapamycin (mTOR) pathway is involved in the regulation of osteoporosis and has been proven to be related to VEGF secretion and angiogenesis. Therefore, this study aimed to explore the effects of PNS on ovariectomized rats with osteoporotic fracture through the PI3K/AKT/mTOR pathway and angiogenesis-related factors. Female Sprague-Dawley rats were randomly divided into normal control, fracture model, ovariectomized fracture model, low-dose PNS (100 mg/kg/d), and high-dose PNS (200 mg/kg/d). The ovariectomized rat fracture model was established. In low and high dose groups, PNS was administered intraperitoneally. The vascularization of fracture ends was detected in vitro by micro-CT on the 7th, 14th, and 21st day after modeling, and the area and number of blood vessels in the unit field of vision of the callus healing plane were seen by hematoxylin-eosin staining. The expression levels of PI3K, AKT1, mTOR, hypoxia inducible factor-1; VEGF: vascular endothelial growth factor (HIF-1), VEGF, Ang-1, VEGFR2, and angiopoietin like 2 Gene (ANGPTL2) were determined using Western blotting. In the PNS treatment group, the area of cortical bone increased, the area of callus decreased, and the number and area of blood vessels increased significantly when compared with the ovariectomized fracture model group. PNS regulates the PI3K/AKT/mTOR signaling pathway and promotes the expression of vascular-related cytokines (VEGF, Ang-1, VEGFR2, and ANGPTL2) in osteoporotic fractures. PNS may regulate the expression of vascular-related factors through the PI3K/AKT/mTOR pathway and promote the healing of osteoporotic fractures in ovariectomized rats.

Non-union during healing of bone fractures affects up to ~5% of patients worldwide. Given the success of recombinant human platelet-derived growth factor-B chain homodimer (rhPDGF-BB) in promoting angiogenesis and bone fusion in the hindfoot and ankle, rhPDGF-BB combined with bovine type I collagen/β-TCP matrix (AIBG) could serve as a viable alternative to autografts in the treatment of non-unions. Defects (~2 mm gaps) were surgically induced in tibiae of skeletally mature New Zealand white rabbits. Animals were allocated to one of four groups-(1) negative control (empty defect, healing for 8 weeks), (2 and 3) acute treatment with AIBG (healing for 4 or 8 weeks), and (4) chronic treatment with AIBG (injection 4 weeks post defect creation and then healing for 8 weeks). Bone formation was analyzed qualitatively and semi-quantitatively through histology. Samples were imaged using dual-energy X-ray absorptiometry and computed tomography for defect visualization and volumetric reconstruction, respectively. Delayed healing or non-healing was observed in the negative control group, whereas defects treated with AIBG in an acute setting yielded bone formation as early as 4 weeks with bone growth appearing discontinuous. At 8 weeks (acute setting), substantial remodeling was observed with higher degrees of bone organization characterized by appositional bone growth. The chronic healing, experimental, group yielded bone formation and remodeling, with no indication of non-union after treatment with AIBG. Furthermore, bone growth in the chronic healing group was accompanied by an increased presence of osteons, osteonal canals, and interstitial lamellae. Qualitatively and semiquantitatively, chronic application of AI facilitated complete bridging of the induced non-union defects, while untreated defects or defects treated acutely with AIBG demonstrated a lack of complete bridging at 8 weeks., (© 2024 Orthopaedic Research Society.)

The immune system plays an important role in fracture healing, by modulating the pro-inflammatory and anti-inflammatory responses occurring instantly upon injury. An imbalance in these responses can lead to adverse outcomes, such as non-union of fractures. Implants are used to support and stabilize complex fractures. Biodegradable metallic implants offer the potential to avoid a second surgery for implant removal, unlike non-degradable implants. However, considering our dynamic immune system it is important to conduct in-depth studies on the immune response to these implants in living systems. In this study, we investigated the immune response to Mg and Mg-10Gd in vivo in a rat femur fracture model with external fixation. In vivo imaging using liposomal formulations was used to monitor the fluorescence-related inflammation over time. We combine ex vivo methods with our in vivo study to evaluate and understand the systemic and local effects of the implants on the immune response. We observed no significant local or systemic effects in the Mg-10Gd implanted group compared to the SHAM and Mg implanted groups over time. Our findings suggest that Mg-10Gd is a more compatible implant material than Mg, with no adverse effects observed in the early phase of fracture healing during our 4-week study. STATEMENT OF SIGNIFICANCE: Degradable metallic implants in form of Mg and Mg-10Gd intramedullary pins were assessed in a rat femur fracture model, alongside a non-implanted SHAM group with special respect to the potential to induce an inflammatory response. This pre-clinical study combines innovative non-invasive in vivo imaging techniques associated with multimodal, ex vivo cellular and molecular analytics. The study contributes to the development and evaluation of degradable biometals and their clinical application potential. The study results indicate that Mg-10Gd did not exhibit any significant harmful effects compared to the SHAM and Mg groups., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Bone fractures are frequently encountered in clinical practice and pose significant challenges, due to the high incidence of delayed healing or non-union. Reduced graphene oxide (rGO) stands out for its unique sensitivity to a wide range of light wavelengths, especially in the near-infrared (NIR) spectrum. In this study, we developed an approach to promote fracture healing using an rGO-HAMC hydrogel activated by NIR stimulation. In vitro experiments demonstrated that NIR-stimulated rGO hydrogel significantly enhanced osteogenesis in bone marrow stromal cells (BMSCs). In an in vivo mouse fracture model, the rGO hydrogel was applied to the fracture site, and NIR light was delivered transdermally, showing promising results in accelerating bone regeneration. These results demonstrate that NIR-stimulated rGO hydrogel significantly accelerates fracture healing, as evidenced by increased bone volume and trabecular thickness. Additionally, transcriptomic analysis revealed that pathways related to B-cell activation are implicated in the enhanced healing effects mediated by NIR-stimulated rGO hydrogel. These findings highlight the potential of the NIR-stimulated rGO hydrogel as an innovative strategy for bone regeneration, offering promising new avenues for the treatment and management of bone fractures., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Combustible cigarette and heated tobacco products (HTPs), the two most frequently used tobacco products, negatively affect bone healing. However, whether smoking cessation following fracture benefits bone healing is unclear. Therefore, this study investigated the effect of smoking cessation immediately after surgery on reduced fracture healing induced by smoking. Smoking combustible cigarettes and heated tobacco products generates cigarette smoking extracts (CSE) (extracts from combustible cigarettes [cCSE] and from HTPs [hCSE], respectively). In vivo, CSEs were injected intraperitoneally into rat models for 3 weeks before femoral midshaft osteotomy and fixation. The rats were then divided into CSE continuation and cessation groups postoperatively. Micro-computed tomography (μCT) and biomechanical analyses were performed 6 weeks postoperatively to assess bone union at the fracture site. In vivo study showed μCT assessment also revealed significantly higher cortical bone mineral density (p = 0.013) and content (p = 0.013), and a higher bone union score (p = 0.046) at the fracture site in the cCSE cessation group than in the cCSE continuation group. Biomechanical assessment revealed that elasticity at the fracture site was significantly higher in the cCSE cessation group than in the cCSE continuation group (p = 0.041). These findings provide that smoking cessation, particularly of combustible cigarette, immediately after a fracture accelerates bone fracture healing and increases mechanical strength at the fracture site., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Titanium plates are the current gold standard for fracture fixation of the mandible. Magnesium alloys such as WE43 are suitable biodegradable alternatives due to their high biocompatibility and elasticity modulus close to those of cortical bone. By surface modification, the reagibility of magnesium and thus hydrogen gas accumulation per time are further reduced, bringing plate fixation with magnesium closer to clinical application. This study aimed to compare bone healing in a monocortical mandibular fracture model in sheep with a human-standard size, magnesium-based, plasma electrolytic-oxidation (PEO) surface modified miniplate fixation system following 4 and 12 weeks. Bone healing was analyzed using micro-computed tomography and histological analysis with Movat's pentachrome and Giemsa staining. For evaluation of the tissue's osteogenic activity, polychrome fluorescent labeling was performed, and vascularization was analyzed using immunohistochemical staining for alpha-smooth muscle actin. Bone density and bone mineralization did not differ significantly between titanium and magnesium (BV/TV: T1: 8.74 ± 2.30%, M1: 6.83 ± 2.89%, p = 0.589 and T2: 71.99 ± 3.13%, M2: 68.58 ± 3.74%, p = 0.394; MinB: T1: 26.16 ± 9.21%, M1: 22.15 ± 7.99%, p = 0.818 and T2: 77.56 ± 3.61%, M2: 79.06 ± 4.46%, p = 0.699). After 12 weeks, minor differences were observed regarding bone microstructure, osteogenic activity, and vascularization. There was significance with regard to bone microstructure (TrTh: T2: 0.08 ± 0.01 mm, M2: 0.06 ± 0.01 mm; p = 0.041). Nevertheless, these differences did not interfere with bone healing. In this study, adequate bone healing was observed in both groups. Only after 12 weeks were some differences detected with larger trabecular spacing and more vessel density in magnesium vs titanium plates. However, a longer observational time with full resorption of the implants should be targeted in future investigations.

Ethnopharmacological Relevance: Hai-Honghua medicinal liquor (HHML), an external Chinese herbal formula preparation, is often applied to treat freshly closed tibia/fibular fractures, ankle fractures, and other bone-related disorders, but the related molecular mechanism is unclear., Aim of the Study: To evaluate the therapeutic effect of HHML in patients with tibial/fibular and ankle fractures, and to explore its related possible mechanism., Methods and Materials: A total of 182 patients with tibia/fibular fractures and 183 patients with ankle fractures were enrolled in this study. A randomized, controlled, unblinded clinical trial was designed to evaluate the therapeutic effect of HHML on tibial/fibular and ankle fractures. The chemical compositions of HHML were analyzed by the HPLC-Q-Extractive MS/MS. Furthermore, a rat tibial fracture model was established to evaluate the therapeutic effects of HHML in promoting fracture healing, and the mouse embryonic osteoblasts cell line of MC3T3-E1 was further carried out to explore the mechanisms of HHML on osteoblast differentiation., Results: In the clinical evaluation, HHML treatment significantly shortened the time for pain and swelling in patients with tibial/fibular fractures (P < 0.01) and ankle fractures (P < 0.01), and the incidence of complications was significantly reduced as well. Subsequently, 116 constituents were identified from HHML via HPLC-Q-TOF-MS/MS analysis. In vivo, no obvious changes in weight were observed in HHML-treated rats. Moreover, the levels of bone formation markers (including osteocalcin (OCN), N-terminal propeptide of type I procollagen (PINP), alkaline phosphatase (ALP), calcium (Ca) and substance P) in rat serum were significantly increased in HHML-treated rats compared with model rats (P < 0.05). Micro-CT analysis showed bone mineral density (BMD), bone volume fraction (BV/TV), trabecular thickness (Tb.Th) of the HHML-treated rats were significantly increased (P < 0.05, vs. Model) while trabecular separation (Tb.Sp) and structure model index (SMI) values were significantly reduced (P < 0.05, vs. Model). Histological analysis showed that HHML treatment promoted the healing of fractures and cartilage repair, and increased the osteoblasts and collagen fibers. Furthermore, our results also revealed HHML could promote MC3T3-E1 cells proliferation and osteoblast differentiation via regulation of the runt-related transcription factor 2 (RUNX2), bone alkaline phosphatase (BALP), and OCN by activating phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathway, which confirmed by adding PI3K chemical inhibitor of LY294002., Conclusion: HHML treatment is a reliable remedy for fractures in tibial and ankle by promotion of osteogenic differentiation via activation of PI3K/Akt pathway., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest regarding the publication of this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Osthole, a natural coumarin derivative, has been shown to have multiple pharmacological activities. However, its effect on osteoporotic fracture has not yet been examined. This research was designed to explore the unknown role and potential mechanism of osthole on osteoporotic fracture healing. We first evaluated the osteogenic and angiogenic abilities of osthole. Then angiogenesis-related assays were conducted to investigate the relationship between osteogenesis and angiogenesis, and further explore its molecular mechanism. After that, we established osteoporotic fracture model in ovariectomy-induced osteoporosis rats and treated the rats with osthole or placebo. Radiography, histomorphometry, histology, and sequential fluorescent labeling were used to evaluate the effect of osthole on osteoporotic fracture healing. In vitro research revealed that osthole promoted osteogenesis and up-regulated the expression of angiogenic-related markers. Further research found that osthole couldn't facilitate the angiogenesis of human umbilical vein endothelial cells in a direct manner, but it possessed the ability to induce the osteogenesis-angiogenesis coupling of bone marrow mesenchymal stem cells (BMSCs). Mechanistically, this was conducted through activating the Wnt/β-catenin pathway. Subsequently, using ovariectomy-induced osteoporosis tibia fracture rat model, we observed that osthole facilitated bone formation and CD31 hi EMCN hi type H-positive capillary formation. Sequential fluorescent labeling confirmed that osthole could effectively accelerate bone formation in the fractured region. The data above indicated that osthole could accelerate osteoporotic fracture healing by inducing the osteogenesis-angiogenesis coupling of BMSCs via the Wnt/β-catenin pathway, which implied that osthole may be a potential drug for treating osteoporosis fracture., (© 2024 John Wiley & Sons Ltd.)

Fractures occur commonly with multiple injuries, and their incidence has increased in recent years. Trace amounts of cobalt are necessary for many living organisms as it stimulates hematopoiesis and improves bone health. However, cobalt is also toxic, as it might cause allergic reactions and tissue destruction. These factors limit the application of cobalt in some medical fields. We studied the tea polysaccode-cobalt complex (TPS-Co) prepared from Qingzhuan Dark Tea polysaccharides. We used 6-week-old Sprague-Dawley rats to establish a femoral fracture model and evaluated the effects of CoCl 2 and TPS-Co on the healing of femoral fractures. In this study, treatment with TPS-Co for the same content of cobalt intake decreased the side effects associated with CoCl 2 treatment and accelerated the healing of femoral fractures in rats. This treatment method promoted angiogenesis by upregulating the expression of vascular endothelial growth factor and hypoxia-inducible factor. Bone formation was promoted via the upregulation of the expression of bone morphogenetic protein 2 and serum bone alkaline phosphatase. TPS-Co was found to actively regulate bone and vascular systems, resulting in significant bone regeneration effects. Therefore, the Qingzhuan Dark Tea polysaccharide cobalt complex might be used as an additive or drug to promote fracture healing, and thus, it might have a huge market value.

Teriparatide is an anabolic drug sometimes administered to patients who have atypical femoral fracture (AFF). However, whether teriparatide has beneficial effects on bone healing remains uncertain. The present study aimed to analyze the association between teriparatide and bone healing in complete AFF. A total of 59 consecutive cases (58 patients) who underwent intramedullary nailing for complete AFF were categorized based on postoperative use of teriparatide into the non-teriparatide (non-TPTD, n = 34) and teriparatide groups (TPTD, n = 25). Time-to-bone union was evaluated and compared between the two groups. Additionally, multiple regression analysis was performed to evaluate factors affecting time-to-bone union. All participants were women, with a mean age of 77.6 years (range: 62-92). No significant difference in time-to-bone union was found between the non-TPTD and TPTD groups (5.5 months vs. 5.8 months, p = 0.359). Two patients in the non-TPTD group underwent reoperation (p = 0.503) due to failure caused by inadequate fixation, and both achieved bone healing after additional fixation with blocking screws. Multiple regression analysis revealed that the anterior gap of the fracture site postoperatively was a factor affecting time-to-bone union (p = 0.014). The beneficial effect of teriparatide on bone healing in complete AFF could not be confirmed. Additional randomized controlled trials are required. Nonetheless, appropriate techniques, including efforts to reduce the gap on the tensile side during the surgery, are important for reliable bone healing., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Antiresorptive medications do not negatively affect fracture healing in humans. Teriparatide may decrease time to fracture healing. Romosozumab has not shown a beneficial effect on human fracture healing., Background: Fracture healing is a complex process. Uncertainty exists over the influence of osteoporosis and the medications used to treat it on fracture healing., Methods: Narrative review authored by the members of the Fracture Working Group of the Committee of Scientific Advisors of the International Osteoporosis Foundation (IOF), on behalf of the IOF and the Société Internationale de Chirurgie Orthopédique et de Traumatologie (SICOT)., Results: Fracture healing is a multistep process. Most fractures heal through a combination of intramembranous and endochondral ossification. Radiographic imaging is important for evaluating fracture healing and for detecting delayed or non-union. The presence of callus formation, bridging trabeculae, and a decrease in the size of the fracture line over time are indicative of healing. Imaging must be combined with clinical parameters and patient-reported outcomes. Animal data support a negative effect of osteoporosis on fracture healing; however, clinical data do not appear to corroborate with this. Evidence does not support a delay in the initiation of antiresorptive therapy following acute fragility fractures. There is no reason for suspension of osteoporosis medication at the time of fracture if the person is already on treatment. Teriparatide treatment may shorten fracture healing time at certain sites such as distal radius; however, it does not prevent non-union or influence union rate. The positive effect on fracture healing that romosozumab has demonstrated in animals has not been observed in humans., Conclusion: Overall, there appears to be no deleterious effect of osteoporosis medications on fracture healing. The benefit of treating osteoporosis and the urgent necessity to mitigate imminent refracture risk after a fracture should be given prime consideration. It is imperative that new radiological and biological markers of fracture healing be identified. It is also important to synthesize clinical and basic science methodologies to assess fracture healing, so that a convergence of the two frameworks can be achieved., (© 2024. The Author(s).)

One of the factors that predispose to fractures is liver damage. Interestingly, fractures are sometimes accompanied by abnormal liver function. Polyene phosphatidylcholine (PPC) is an important liver repair drug. We wondered if PPC had a role in promoting fracture healing. A rat model of tibial fracture was developed using the modified Einhorn model method. X-rays were used to detect the progression of fracture healing. Progress of ossification and angiogenesis at the fracture site were analyzed by Safranin O/fast green staining and CD31 immunohistochemistry. To investigate whether PPC has a direct angiogenesis effect, HUVECs were used. We performed MTT, wound healing, Transwell migration, and tube formation assays. Finally, RT-qPCR and Western blot analysis were used to study the underlying mechanism. The results showed that PPC significantly shortened the apparent recovery time of mobility in rats. PPC treatment significantly promoted the formation of cartilage callus, endochondral ossification, and angiogenesis at the fracture site. In vitro, PPC promoted the proliferative viability of HUVECs, their ability to heal wounds, and their ability to penetrate membranes in the Transwell apparatus and increased the tube formation of cells. The transcription of VEGFA, VEGFR2, PLCγ, RAS, ERK1/2 and MEK1/2 was significantly up regulated by PPC. Further, the protein level results demonstrated a significant increase in the expression of VEGFA, VEGFR2, MEK1/2, and ERK1/2 proteins. In conclusion, our findings suggest that PPC promotes angiogenesis by activating the VEGFA/VEGFR2 and downstream signaling pathway, thereby accelerating fracture healing., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The fracture healing outcome is largely dependent on the quantities as well as osteogenic differentiation capacities of mesenchymal stem cells (MSCs) at the lesion site. Herein, macrophage membrane (MM)-reversibly cloaked nanocomplexes (NCs) are engineered for the lesion-targeted and hierarchical co-delivery of short stromal derived factor-1α peptide (sSDF-1α) and Ckip-1 small interfering RNA (Ckip-1 siRNA, siCkip-1) to promote bone repair by concurrently fostering recruitment and osteogenic differentiation of endogenous MSCs. To construct the NCs, a membrane-penetrating α-helical polypeptide first assembles with siCkip-1, and the cationic NCs are sequentially coated with catalase and an outer shell of sSDF-1α-anchored MM. Due to MM-assisted inflammation homing, intravenously injected NCs could efficiently accumulate at the fractured femur, where catalase decomposes the local hydrogen peroxide to generate oxygen bubbles that drives the shedding of sSDF-1α-anchored MM in the extracellular compartment. The exposed, cationic inner core thus enables robust trans-membrane delivery into MSCs to induce Ckip-1 silencing. Consequently, sSDF-1α-guided MSCs recruitment cooperates with siCkip-1-mediated osteogenic differentiation to facilitate bone formation and accelerate bone fracture healing. This study provides an enlightened strategy for the hierarchical co-delivery of macromolecular drugs into different cellular compartments, and it also renders a promising modality for the management of fracture healing., (© 2024. The Author(s).)

Background: As a two-stage surgical procedure, Masquelet's technique has been used to care for critical-size bone defects (CSD). We aimed to determine the effects of modified and altered bone cement with biological or chemical enriching agents on the progression of Masquelet's induced membrane (IM) applied to a rat femur CSD model, and to compare the histopathological, biochemical, and immunohistochemical findings of these cements to enhance IM capacity., Methods: Thirty-five male rats were included in five groups: plain polymethyl methacrylate (PMMA), estrogen-impregnated PMMA (E+PMMA), bone chip added PMMA (BC+PMMA), hydroxyapatite-coated PMMA (HA) and calcium phosphate cement (CPC). The levels of bone alkaline phosphatase (BALP), osteocalcin (OC), and tumor necrosis factor-alpha (TNF-α) were analyzed in intracardiac blood samples collected at the end of 4 weeks of the right femur CSD intervention. All IMs collected were fixed and prepared for histopathological scoring. The tissue levels of rat-specific Transforming Growth Factor-Beta (TGF-β), Runt-related Transcription Factor 2 (Runx2), and Vascular Endothelial Growth Factor (VEGF) were analyzed immunohistochemically., Results: Serum levels of BALP and OC were significantly higher in E+PMMA and BC+PMMA groups than those of other groups (P = 0.0061 and 0.0019, respectively). In contrast, TNF-α levels of all groups with alternative bone cement significantly decreased compared to bare PMMA (P = 0.0116). Histopathological scores of E+PMMA, BC+PMMA, and CPC groups were 6.86 ± 1.57, 4.71 ± 0.76, and 6.57 ± 1.51, respectively, which were considerably higher than those of PMMA and HA groups (3.14 ± 0.70 and 1.86 ± 0.69, respectively) (P < 0.0001). Significant increases in TGF-β and VEGF expressions were observed in E+PMMA and CPC groups (P = 0.0001 and <0.0001, respectively) whereas Runx2 expression significantly increased only in the HA group compared to other groups (P < 0.0001)., Conclusions: The modified PMMA with E and BC, and CPC as an alternative spacer resulted in a well-differentiated IM and increased IM progression by elevating BALP and OC levels in serum and by mediating expressions of TGF-β and VEGF at the tissue level. Estrogen-supplemented cement spacer has yielded promising findings between modified and alternative bone cement., Competing Interests: Declaration of competing interest None., (Copyright © 2024. Published by Elsevier Ltd.)

Methylphenidate and mixed amphetamine salts (MAS) are psychostimulant medications widely prescribed for various psychiatric disorders. Although these medications are known to adversely impact bone mineral content and density, as well as biomechanical integrity during skeletal development in rats, their effect on bone density in children remains largely unknown. The primary aim of this work was to investigate the effects of methylphenidate and MAS on bone density following distal radius fractures in pediatric populations, and secondarily assess any impact on healing. The retrospective case-control study was designed to assess fracture healing in patients treated with stimulant drugs and matched controls. For the primary outcome, X-rays ( n  = 188) were evaluated using an optical density image analysis technique to compare bone density throughout the bone healing process. Results showed that methylphenidate and MAS significantly reduced bone healing by approximately 20% following distal radius fractures in these children. The data also suggested that duration of psychostimulant use played a role in bone healing; the longer the treatment (1-5 years), the lower the bone density was observed (by approximately 52%) as compared to controls (no medication). However, subjects taking these drugs for longer than 5 years did not show a significant difference. Our results suggested that children taking psychostimulants for up to 5 years had slower bone healing following distal radius fractures. Orthopedic surgeons planning elective surgeries should be cognizant of this as a potential issue in recovery after any elective bone procedures and preoperatively optimize bone health as well as counsel patients and their families., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective analgesics commonly used in fracture management. Although previously associated with delayed fracture healing, multiple studies have demonstrated their safety, with minimal risks of fracture healing. Given the current opioid crisis in the United States, alternate pain control modalities are essential to reduce opioid consumption. This study aims to determine whether the combination of oral acetaminophen and intravenous ketorolac is a viable alternative to opioid-based pain management in closed tibial shaft fractures treated with intramedullary nailing., Methods: We conducted a randomized controlled trial evaluating postoperative pain control and opioid consumption in patients with closed tibial shaft fractures who underwent intramedullary nailing. Patients were randomized into an NSAID-based pain control group (52 patients) and an opioid-based pain control group (44 patients). Visual analog scale (VAS) scores and morphine milligram equivalents (MMEs) were evaluated at 12-hour postoperative intervals during the first 48 hours after surgery. Nonunion and delayed healing rates were recorded for both groups., Results: A statistically significant decrease in MMEs was noted at every measured interval (12, 24, 36, and 48 hours) in the NSAID group compared with the opioid group ( P -value 0.001, 0.001, 0.040, 0.024, respectively). No significant change in visual analog scale scores was observed at 12, 36, and 48 hours between both groups ( P -value 0.215, 0.12, and 0.083, respectively). A significant decrease in VAS scores was observed at the 24-hour interval in the NSAID group compared with the opioid group ( P -value 0.041). No significant differences in union rates were observed between groups ( P -value 0.820)., Discussion: Using an NSAID-based postoperative pain protocol led to a decrease in opioid consumption without affecting pain scores or union rates. Owing to the minimal risk of short-term NSAID use, their role in the perioperative management of tibia shaft fractures is justified, especially when they reduce opioid consumption markedly., Level of Evidence: Therapeutic Level I., (Copyright © 2024 by the American Academy of Orthopaedic Surgeons.)

The aim of this study was to evaluate the effects of favipiravir on fracture healing. Forty-eight female rats which had a femur fracture with intramedullary Kirschner wire fixation performed were divided into 6 groups; 2 control groups (C1, C2) and 4 experimental groups (F1, F2, F3, F4). The control groups (C1, C2) received physiological saline by oral gavage for 14 days. Two of the experimental groups (F1, F2) received favipiravir by oral gavage for 5 days, whereas the other groups (F3, F4) received it for 14 days. C1, F1 and F3 groups were sacrificed and evaluated on the 14th day, and C2, F2 and F4 groups were sacrificed and evaluated on the 28th day. The fracture sites were assessed for healing radiologically using the Lane and Sandhu scoring system, and assessed histologically using the Huo et al. scoring system. There was no difference between the groups regarding radiological and histological evaluations made on the 14th day (P > .05, P=.216, respectively). On the 28th day, the radiological scores were found to be significantly higher in the control group when compared to the experimental groups (P < .05). Histologically, the control group demonstrated better fracture healing than the groups that had favipiravir administered (P < .001). This study has shown that favipiravir can have negative effects on fracture healing both radiologically and histologically.

Bone fracture healing is a complex process in which specific molecular knowledge is still lacking. The citrulline-arginine-nitric oxide metabolism is one of the involved pathways, and its enrichment via citrulline supplementation can enhance fracture healing. This study investigated the molecular effects of citrulline supplementation during the different fracture healing phases in a rat model. Microcomputed tomography (μCT) was applied for the analysis of the fracture callus formation. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) and liquid-chromatography tandem mass spectrometry (LC-MS/MS) were used for lipid and protein analyses, respectively. μCT analysis showed no significant differences in the fracture callus volume and volume fraction between the citrulline supplementation and control group. The observed lipid profiles for the citrulline supplementation and control group were distinct for the different fracture healing stages. The main contributing lipid classes were phosphatidylcholines (PCs) and lysophosphatidylcholines (LPCs). The changing effect of citrulline supplementation throughout fracture healing was indicated by changes in the differentially expressed proteins between the groups. Pathway analysis showed an enhancement of fracture healing in the citrulline supplementation group in comparison to the control group via improved angiogenesis and earlier formation of the soft and hard callus. This study showed the molecular effects on lipids, proteins, and pathways associated with citrulline supplementation during bone fracture healing, even though no effect was visible with μCT.

Background and Objectives: We aimed to determine the effects of vanillic acid (VA) on fracture healing radiologically, histologically, immunohistochemically, and biomechanically using a rat femur open fracture injury model., Methods: 32 male Wistar-Albino rats were used and divided into two groups: the study group (VA) and the control group. From the time they were operated on until they were sacrificed, the rats in the study group were given 100 mg/kg/day VA by oral gavage. After sacrification, the femurs were analyzed., Results: It was observed that the Huo histological scoring was significantly higher in the VA group (p = 0.001), and the ratio of the amount of callus tissue compared to intact bone tissue was significantly higher. While no significant difference was observed in immunohistochemical H-scores in ColI antibody staining (p = 1.000), a borderline significant difference in favor of VA was observed in ColIII antibody staining (p = 0.078). In biomechanical analysis, failure load (N), total energy (J), maximum stress (MPa), and stiffness (N/mm) measurements were significantly higher in the VA group (p = 0.040, p = 0.021, p = 0.015, and p = 0.035, respectively)., Conclusion: It has been observed that VA, with its antioxidative properties, increases fracture healing in rats, in which an open fracture model was created. We are hopeful that such an antioxidant, which is common in nature, will increase fracture healing. Since this study is the first to examine the effect of VA on fracture healing, further studies are needed., Competing Interests: The authors report no conflicts of interest in this work.

This study aimed to explore the effects of peroxisome proliferator-activated receptor γ (PPARγ) inhibition on fracture healing of nonunion and the underlying mechanisms. Bone marrow mesenchymal stem cells (BMSCs) were treated with PPARγ antagonist GW9662 (5 μM, 10 μM). Alkaline phosphatase (ALP) staining and Alizarin Red S was used to assess early stage of osteogenesis and osteogenic differentiation. GW9662 (1 mg/kg/day) were administered intraperitoneally into the rats with bone fracture. Bone healing processes in the rat femur fracture model were recorded and assessed by radiographic methods on Weeks 8, 14, and 20 postoperation. Osteogenesis and angiogenesis at the fracture sites were evaluated by radiographic and histological methods on postoperative Week 20. GW9662 treatment increased ALP activity and Alp mRNA expression in rat BMSCs. Moreover, GW9662 administration increased matrix mineralization and mRNA and protein levels of Bmp2 and Runx2 in the BMSCs. In addition, GW9662 treatment improved radiographic score in the fracture rats and increased osteogenesis-related proteins, including type I collagen, osteopontin, and osteoglycin, in the bone tissues of the fracture sites. In conclusion, PPARγ inhibition promotes osteogenic differentiation of rat BMSCs, as well as improves the fracture healing of rats through Bmp2/Runx2 signaling pathway in the rat model of bone fracture., (© 2024 Wiley Periodicals LLC.)

This paper explores the role of botulinum neurotoxin in aiding fracture recovery through temporary muscle paralysis. Specifically, it investigates the effects of botulinum neurotoxin-induced paralysis of the sternocleidomastoid muscle on clavicle fractures in rats. The research aims to assess safety, effectiveness, and the impact on fracture healing. Healthy male Albino Wistar rats were divided into four groups: clavicle fracture, botulinum neurotoxin injection, both, and control. Surgeries were conducted under anaesthesia, and postoperatively, animals were monitored for 28 days. Euthanasia and radiological assessment followed, examining fracture healing and muscle changes, while tissues were histopathologically evaluated. The modified Lane-Sandhu scoring system was used for the radiographic evaluation of clavicle fractures, and the results varied from complete healing to nonunion. Histopathological examination at 28 days postfracture showed fibrous tissue, mesenchymal cells, and primary callus formation in all groups. Despite varied callus compositions, botulinum neurotoxin administration did not affect clavicle healing, as evidenced by similar scores to the control group. Several studies have explored botulinum neurotoxin applications in fracture recovery. Research suggests its potential to enhance functional recovery in certain types of fractures. Theoretical benefits include managing muscle spasticity, aiding reduction techniques, and preventing nonunion. However, botulinum neurotoxin's transient effect and nonuniversal applications should be considered. The present study found that botulinum toxin had no clear superiority in healing compared to controls, while histological evaluation showed potential adverse effects on muscle tissue. Further research is essential to understand its risk-benefit balance and long-term effects., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2024 Themistoklis Vampertzis et al.)

Background: Elderly patients suffering from osteoporotic fractures are more susceptible to delayed union or nonunion, and their bodies then are in a state of low-grade chronic inflammation with decreased antioxidant capacity. Tanshinone IIA is widely used in treating cardiovascular and cerebrovascular diseases in China and has anti-inflammatory and antioxidant effects. We aimed to observe the antioxidant effects of Tanshinone IIA on mesenchymal stem cells (MSCs), which play important roles in bone repair, and the effects of local application of Tanshinone IIA using an injectable biodegradable hydrogel on osteoporotic fracture healing., Methods: MSCs were pretreated with or without different concentrations of Tanshinone IIA followed by H 2 O 2 treatment. Ovariectomized (OVX) C57BL/6 mice received a mid-shaft transverse osteotomy fracture on the left tibia, and Tanshinone IIA was applied to the fracture site using an injectable hydrogel., Results: Tanshinone IIA pretreatment promoted the expression of nuclear factor erythroid 2-related factor 2 and antioxidant enzymes, and inhibited H 2 O 2 -induced reactive oxygen species accumulation in MSCs. Furthermore, Tanshinone IIA reversed H 2 O 2 -induced apoptosis and decrease in osteogenic differentiation in MSCs. After 4 weeks of treatment with Tanshinone IIA in OVX mice, the bone mineral density of the callus was significantly increased and the biomechanical properties of the healed tibias were improved. Cell apoptosis was decreased and Nrf2 expression was increased in the early stage of callus formation., Conclusions: Taken together, these results indicate that Tanshinone IIA can activate antioxidant enzymes to protect MSCs from H 2 O 2 -induced cell apoptosis and osteogenic differentiation inhibition. Local application of Tanshinone IIA accelerates fracture healing in ovariectomized mice., (© 2024. The Author(s).)

Delayed repair of fractures seriously impacts patients' health and significantly increases financial burdens. Consequently, there is a growing clinical demand for effective fracture treatment. While current materials used for fracture repair have partially addressed bone integrity issues, they still possess limitations. These challenges include issues associated with autologous material donor sites, intricate preparation procedures for artificial biomaterials, suboptimal biocompatibility, and extended degradation cycles, all of which are detrimental to bone regeneration. Hence, there is an urgent need to design a novel material with a straightforward preparation method that can substantially enhance bone regeneration. In this context, we developed a novel nanoparticle, mPPTMP195, to enhance the bioavailability of TMP195 for fracture treatment. Our results demonstrate that mPPTMP195 effectively promotes the differentiation of bone marrow mesenchymal stem cells into osteoblasts while inhibiting the differentiation of bone marrow mononuclear macrophages into osteoclasts. Moreover, in a mouse femur fracture model, mPPTMP195 nanoparticles exhibited superior therapeutic effects compared to free TMP195. Ultimately, our study highlights that mPPTMP195 accelerates fracture repair by preventing HDAC4 translocation from the cytoplasm to the nucleus, thereby activating the NRF2/HO-1 signaling pathway. In conclusion, our study not only proposes a new strategy for fracture treatment but also provides an efficient nano-delivery system for the widespread application of TMP195 in various other diseases., (© 2024. The Author(s).)

Background: A fracture is considered a medical emergency leading to considerable complications., Aim: This study aimed to describe the accelerating action of Ag-NPs-FG on fracture healing in rabbits., Methods: Silver NPs (AgNPs) were reduced with fenugreek (FG), loaded into a starch gel base, and investigated for their morphology, size, and charge. Four equal groups were randomly formed of 40 adult male rabbits. A 3.5 mm diameter bone defect was created at the proximal metaphysis of the right tibia in each rabbit. Groups 1-4 were injected with placebo saline, AgNPs-FG, plain gel, and FG-gel at the bone defect zone, respectively. The healing was assessed for 8 weeks postoperatively based on the radiographic, bone turnover markers, and histopathological examinations., Results: The AgNPs-FG was obtained as a faint reddish color, spherical in shape, with an absorbance of 423 nm, a size of 118.0 ± 1.7 nm, and a surface charge of -7.8 ± 0.518 mV. The prepared AgNPs-FG hydrogel was clear, translucent, and homogenous. The pH values were 6.55-6.5 ± 0.2, the viscosity of 4,000 and 1,875 cPs, and spreadability of 1.6 ± 0.14 and 2.0 ± 0.15 for both FG and AgNPs-FG hydrogel, respectively. The radiographic union scale was significantly ( p < 0.05) improved in group 2 with a significant ( p < 0.05) increase in bone turnover markers was found in comparison to other treated groups. Histopathological examination revealed the formation of mature bone on the 28th postoperative day in groups 2 and 4., Conclusion: Colloidal nano-formulation of AgNPs-FG loaded hydrogel could be a promising formulation to accelerate rabbits' tibial bone healing process., Competing Interests: The authors declare that there is no conflict of interest.

Introduction: Glucocorticoids delay fracture healing and induce osteoporosis. Angiogenesis plays an important role in bone repair after bone injury. Plasminogen activator inhibitor-1 (PAI-1) is the principal inhibitor of plasminogen activators and an adipocytokine that regulates metabolism. However, the mechanisms by which glucocorticoids delay bone repair remain unclear., Materials and Methods: Therefore, we herein investigated the roles of PAI-1 and angiogenesis in glucocorticoid-induced delays in bone repair after femoral bone injury using PAI-1-deficient female mice intraperitoneally administered dexamethasone (Dex)., Results: PAI-1 deficiency significantly attenuated Dex-induced decreases in the number of CD31-positive vessels at damaged sites 4 days after femoral bone injury in mice. PAI-1 deficiency also significantly ameliorated Dex-induced decreases in the number of CD31- and endomucin-positive type H vessels and CD31-positive- and endomucin-negative vessels at damaged sites 4 days after femoral bone injury. Moreover, PAI-1 deficiency significantly mitigated Dex-induced decreases in the expression of vascular endothelial growth factor as well as hypoxia inducible factor-1α, transforming growth factor-β1, and bone morphogenetic protein-2 at damaged sites 4 days after femoral bone injury., Conclusion: The present results demonstrate that Dex-reduced angiogenesis at damaged sites during the early bone-repair phase after femoral bone injury partly through PAI-1 in mice., (© 2024. The Japanese Society Bone and Mineral Research.)

Objective: To evaluate the effect of subcutaneous teriparatide therapy on fracture healing rate and change in bone mass density in osteoporotic hip fractures., Methods: The meta-analysis was done from September to December 2022, and comprised literature search on Wanfang, CNKI, VIP, PubMed, Embase, Cochrane Library, and Web of Science databases from the establishment of the respective database till December 2022. The relevant journals of the library of Macao University of Science and Technology, China, were manually searched for randomised controlled trials of teriparatide in the treatment of osteoporotic hip fractures. The shortlisted studies were subjectd to Cochrane Risk of Bias tool and the Jadad Rating Scale. Meta-analysis was done using the RevMan 5.4 software provided by the Cochrane Collaboration Network. Fracture healing rate and bone mineral density were the primary outcome measures, while mortality, adverse events, malformations, complications, subsequent fractures, timed-up-and-go test, visual analogue scale score, and procollagen type I N-terminal propeptide were the secondary outcome measures., Results: Of the 1,094 articles retrieved, 8(0.7%) randomised controlled trials were analysed. There were 744 patients; 372(50%) in the teriparatide group and 372(50%) in the control group. Fracture healing rate was not significantly different (p=0.82), while bone mineral density was significantly different between the groups (p<0.001). Mortality, adverse events, deformity, and complications were not significantly different (p>0.05), while subsequent fractures, timed-up-and-go score, visual analogue scale score and procollagen type I N-terminal propeptide were significantly different between the groups (p<0.05)., Conclusion: The literature did not support teriparatide's ability to improve the healing rate of osteoporotic hip fractures, or to reduce mortality, adverse events, malformations, and complications. In addition, teriparatide could increase bone mineral density of osteoporotic hip fractures and the procollagen type I N-terminal propeptide value, alleviate hip pain, and reduce subsequent fracture rates. This trial is registered with PROSPERO with registration number CRD42022379832.

Quercetin is widely distributed in plants as a flavonol compound with multiple biological activities. It has been found that quercetin can regulate bone homeostasis through multiple pathways and targets. This study investigated the role and specific molecular mechanisms of quercetin in regulating osteoblast viability, proliferation, migration and osteogenic differentiation. A mouse model of traumatic fracture was established and then 100 mg/kg quercetin corn oil suspension was gavaged at the same time every day for 28 days. miR-6089 and E2F transcription factor 2 (E2F2) expression levels in mice were measured. Fracture healing in mice was observed. MC3T3-E1 cells were transfected with plasmids targeting miR-6089 and E2F2, and cell viability, proliferation, migration, apoptosis, and osteogenic differentiation were determined. The targeting relationship between miR-6089 and E2F2 was verified. In vivo experiments showed that quercetin significantly increased osteocalcin (OCN) expression (P<0.05) and promoted fracture healing in traumatic fracture (TF) mice. miR-6089 expression was down-regulated (P<0.05) and E2F2 expression was up-regulated (P<0.05) in TF mice. Quercetin promoted miR-6089 expression and inhibited E2F2 expression (both P<0.05). In vitro results showed that quercetin promoted miR-6089 expression and inhibited E2F2 expression in a dose-dependent manner (both P<0.05). Quercetin dose-dependently promoted MC3T3-E1 cell viability, proliferation, migration, and osteogenic differentiation, and inhibited MC3T3-E1 cell apoptosis (all P<0.05). Up-regulating miR-6089 further promoted MC3T3-E1 cell viability, proliferation, migration and osteogenic differentiation, and inhibited MC3T3-E1 cell apoptosis (all P<0.05). miR-6089 targeted and regulated E2F2 expression. Up-regulating E2F2 attenuated the promoting effect of up-regulated miR-6089 on MC3T3-E1 cell viability, proliferation, migration, osteogenic differentiation, and inhibition of apoptosis (all P<0.05). We conclude that quercetin enhances osteoblast viability, proliferation, migration, and osteogenic differentiation by modulating the miR-6089/E2F2 axis, thereby promoting fracture healing.

Background: The bone regeneration potential of erythropoietin (EPO) is not yet fully investigated, but some previous experimental studies demonstrated that its application activated the differentiation of osteoblasts and promoted bone formation., Aim: The aim of the present study was to evaluate the effects of recombinant human erythropoietin (rhEpo) on bone healing in cats with fragmented long bone fractures., Methods: Twelve cats were divided into two groups-control ( n = 6) in which physiological saline was applied at the fracture gap site and EPO ( n = 6) with the application of 1,000 IU rhEpo. The effects of EPO on blood erythrocyte counts, hemoglobin content, and hematocrit were monitored by serial complete blood cell tests, whereas bone formation was evaluated by clinical and radiographic examinations on post-operative weeks 1, 2, 3, 4, 6, and 8., Results: All tested blood parameters were within the reference range. A faster fracture healing and full limb weight-bearing were observed in the EPO group, with statistically significant differences with respect to the control group., Conclusion: The obtained results confirmed that the local application of rhEpo promoted bone healing in cats with fragmented femoral fractures and increased bone callus strength without having significant systemic effects., Competing Interests: The authors declare no conflict of interest.

Introduction: Bisphosphonates (BPs) are one of the most often used drugs to lower fracture risk in osteoporosis patients; nonetheless, BPs have been linked to atypical femoral fracture (AFF). Teriparatide (TPTD) is a parathyroid hormone analogue and anabolic drug that may accelerate fracture repair. TPTD has been considered as a possible treatment for AFF, particularly those caused by BP use. We evaluate the effect of TPTD on AFF in this systematic review and meta-analysis., Materials and Methods: A thorough search of: Web of Science, Scopus, PubMed, and Cochrane was conducted on August 2, 2023. Trials evaluating the effect of TPTD on the incidence of: complete bone healing, non-union, early and delayed bone union, progression of incomplete AFF to complete AFF, and time to bone union were included. Using Review Manager (RevMan) version 5.4, the risk ratio (RR) and mean difference (MD) with the corresponding 95% confidence interval (CI) were estimated for dichotomous and continuous outcomes, respectively. The Newcastle-Ottawa Scale was used to assess the quality of studies., Results: Eight studies met the eligibility criteria and were included in our analysis. TPTD significantly increased the incidence of early bone union (RR = 1.45, 95% CI [1.13, 1.87], P = 0.004) and time to bone union (MD = -1.56, 95% CI [-2.86, -0.26], P = 0.02) compared to the control group. No significant differences were observed in terms of complete bone healing (RR = 1.09, 95% CI [0.99, 1.13], P = 0.12), non-union (RR = 0.48, 95% CI [0.22, 1.04], P = 0.06), and progression of incomplete AFF to complete AFF (RR = 0.27, 95% CI [0.04, 1.97], P = 0.19)., Conclusions: TPTD is an effective therapy for enhancing and hastening healing following AFF, particularly in postoperative settings. Future large randomized clinical trials are needed to confirm or dispute the results., (© 2023. The Author(s).)

Chronic inflammation and hyperglycemia in diabetic patients increase the risk of implant failure and impaired fracture healing. We previously developed and characterized a titanium (Ti) coating strategy using an imidazolium-based ionic liquid (IonL) with a fully reduced, non-oxidizable High Mobility Group Box 1 (HMGB1) isoform (Ti-IonL-HMGB1) to immunomodulate tissue healing. In this study, we used an open reduction fracture fixation (ORIF) model in non-diabetic (ND) and diabetic (D) rats to further investigate the effectiveness of this Ti-IonL-HMGB1 coating on orthopedic applications. Ninety male Lewis rats (12-15 weeks) were divided into D (n = 45) and ND (n = 45) groups that were distributed into three subgroups based on the type of local treatment received: Ti (uncoated Ti), Ti-IonL, and Ti-IonL-HMGB1 implants. Fracture healing and osseointegration were evaluated using microtomographic, histological, and immunohistochemical analysis of proliferating cell nuclear antigen (PCNA), Runt-related transcription factor 2 (RUNX2), and HMGB1 markers at 2, 10, and 21 days post-ORIF. Scanning Electron Microscopy verified the coating stability after placement. Microtomographic and histological analysis demonstrated increased fracture healing and osseointegration for ND rats in all treatment groups at 10 days, with impaired healing for D rats. Immunohistochemical analysis exhibited elevated PCNA+ and RUNX2+ cells for D animals treated with Ti-IonL-HMGB1 at 21 days compared to all other groups. The immunohistochemical marker HMGB1 was elevated at all time points for D animals in comparison to ND animals, yet was lowered for D tissues near the Ti-IonL-HMGB1 treated implant. Improved osseous healing was demonstrated in D animals with Ti-IonL-HMGB1 treatment by 21 days, compared to D animals with other treatments. To the best of our knowledge, this is the first study analyzing Ti-IonL-HMGB1 implantation in an injury site through ORIF procedures in ND and D rats. This surface approach has potential for improving implanted biomaterials in diabetic environments., Competing Interests: Declaration of competing interest None., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Bone fracture is one of the most common injuries in the human musculoskeletal system. This study was performed to investigate the effects of celastrol on bone wound healing in rats. Bone wound models of Sprague-Dawley rats were treated with low (10 μg/kg) and high (100 μg/kg) celastrol for 14 days. Serum calcium (Ca), phosphorus (P), and alkaline phosphatase (ALP) contents, bone mechanical properties, bone mineral density (BMD), and the levels of osteogenesis-related and inflammation-related proteins were assessed at the end of the experiments. Rats feeding with celastrol grew normally as control. Compared with model, celastrol administration significantly increased fracture strength, elastic load (0.12 vs 0.16 kg/m), bending energy (11.23 vs 14.23 n x mm), and BMD (0.49 vs 0.54 g/cm3), particularly at a high dose. Serum Ca (2.2 vs 2.7 mmol/L) and ALP (217.3 vs 245.8 IU/L) contents were significantly increased after a high dose celastrol administration, although P content did not change. Western blot analyses showed that OPG (0.72 vs 1.15) and COL-1 (0.20 vs 0.42) but not RUNX2 were upregulated significantly after celastrol administration, and IL-1α (0.82 vs 0.37), IL-6 (0.62 vs 0.28), MCP-1(0.68 vs 0.18), and VEGF (0.62 vs 0.42) were significantly downregulated, while IFN-γ was upregulated (0.29 vs 0.46). Our data demonstrate that celastrol effectively promotes the healing of bone wound in rats and may be further explored as a therapeutic agent to treat bone fracture.

The ubiquitin/proteasome system controls the stability of Runx2 and JunB, proteins essential for differentiation of mesenchymal progenitor/stem cells (MPCs) to osteoblasts. Local administration of proteasome inhibitor enhances bone fracture healing by accelerating endochondral ossification. However, if a short-term administration of proteasome inhibitor enhances fracture repair and potential mechanisms involved have yet to be exploited. We hypothesize that injury activates the ubiquitin/proteasome system in callus, leading to elevated protein ubiquitination and degradation, decreased MPCs, and impaired fracture healing, which can be prevented by a short-term of proteasome inhibition. We used a tibial fracture model in Nestin-GFP reporter mice, in which a subgroup of MPCs are labeled by Nestin-GFP, to test our hypothesis. We found increased expression of ubiquitin E3 ligases and ubiquitinated proteins in callus tissues at the early phase of fracture repair. Proteasome inhibitor Bortezomib, given soon after fracture, enhanced fracture repair, which is accompanied by increased callus Nestin-GFP+ cells and their proliferation, and the expression of osteoblast-associated genes and Runx2 and JunB proteins. Thus, early treatment of fractures with Bortezomib could enhance the fracture repair by increasing the number and proliferation of MPCs., Competing Interests: NO authors have competing interests.

Compared with traditional internal fixation devices, bone adhesives are expected to exhibit remarkable advantages, such as improved fixation of comminuted fractures and maintained spatial location of fractured scattered bone pieces in treating bone injuries. In this review, different bone adhesives are summarized from the aspects of bone tissue engineering, and the applications of bone adhesives are emphasized. The concepts of "liquid scaffold" and "liquid plate" are proposed to summarize two different research directions of bone adhesives. Furthermore, significant advances of bone adhesives in recent years in mechanical strength, osseointegration, osteoconductivity, and osteoinductivity are discussed. We conclude this topic by providing perspectives on the state-of-the-art research progress and future development trends of bone adhesives. We hope this review will provide a comprehensive summary of bone adhesives and inspire more extensive and in-depth research on this subject.

Short-chain fatty acids (SCFAs) produced by the gut microbiota have previously been demonstrated to play a role in numerous chronic inflammatory diseases and to be key mediators in the gut-bone signaling axis. However, the role of SCFAs in bone fracture healing and its impact on systemic inflammation during the regeneration process has not been extensively investigated yet. The aim of this study was to first determine the effects of the SCFA butyrate on key cells involved in fracture healing in vitro , namely, osteoclasts and mesenchymal stromal cells (MSCs), and second, to assess if butyrate supplementation or antibiotic therapy impacts bone healing, systemic immune status, and inflammation levels in a murine osteotomy model. Butyrate significantly reduced osteoclast formation and resorption activity in a dose-dependent manner and displayed a trend for increased calcium deposits in MSC cultures. Numerous genes associated with osteoclast differentiation were differentially expressed in osteoclast precursor cells upon butyrate exposure. In vivo , antibiotic-treated mice showed reduced SCFA levels in the cecum, as well as a distinct gut microbiome composition. Furthermore, circulating proinflammatory TNF α , IL-17a, and IL-17f levels, and bone preserving osteoprotegerin (OPG), were increased in antibiotic-treated mice compared to controls. Antibiotic-treated mice also displayed a trend towards delayed bone healing as revealed by reduced mineral apposition at the defect site and higher circulating levels of the bone turnover marker PINP. Butyrate supplementation resulted in a lower abundance of monocyte/macrophages in the bone marrow, as well as reduced circulating proinflammatory IL-6 levels compared to antibiotic- and control-treated mice. In conclusion, this study supports our hypothesis that SCFAs, in particular butyrate, are important contributors to successful bone healing by modulating key cells involved in fracture healing as well as systemic inflammation and immune responses., Competing Interests: All authors declare that they have no conflicts of interest., (Copyright © 2021 Alexandra Wallimann et al.)

The immune system and skeletal system are closely linked. Macrophages are one of the most important immune cells for bone remodeling, playing a prohealing role mainly through M2 phenotype polarization. Baicalein (5,6,7-trihydroxyflavone, BCL) has been well documented to have a noticeable promotion effect on M2 macrophage polarization. However, due to the limitations in targeted delivery to macrophages and the toxic effect on other organs, BCL has rarely been used in the treatment of bone fractures. In this study, we developed mesoporous silica and Fe 3 O 4 composite-targeted nanoparticles loaded with BCL (BCL@MMSNPs-SS-CD-NW), which could be magnetically delivered to the fracture site. This induced macrophage recruitment in a targeted manner, polarizing them toward the M2 phenotype, which was demonstrated to induce mesenchymal stem cells (MSCs) toward osteoblastic differentiation. The mesoporous silicon nanoparticles (MSNs) were prepared with surface sulfhydrylation and amination modification, and the mesoporous channels were blocked with β-cyclodextrin. The outer layer of the mesoporous silicon was added with an amantane-modified NW-targeting peptide to obtain the targeted nanosystem. After entering macrophages, BCL could be released from nanoparticles since the disulfide linker could be cleaved by intracellular glutathione (GSH), resulting in the removal of cyclodextrin (CD) gatekeeper, which is a key element in the pro-bone-remodeling functions such as anti-inflammation and induction of M2 macrophage polarization to facilitate osteogenic differentiation. This nanosystem passively accumulated in the fracture site, promoting osteogenic differentiation activities, highlighting a potent therapeutic benefit with high biosafety.