Non-union Bone Fractures Research Articles

A REVIEW OF ANIMAL MODELS FOR BONE FRACTURE NONUNION AND THEIR ROLE IN STUDYING BIOLOGICAL THERAPY EFFICACY

The bone healing impairment, such as non-union fractures after injuries of long bones, lead to loss of working capacity and result in significant financial costs, which emphasizes the socioeconomic significance of the problem. However, it is not known which method of modeling the non-union bone fractures is more optimal for further research into the effectiveness of biological therapy aimed at treating bone healing impairment. For a detailed study of methods of non-union fracture treatment of, it is necessary to determine the developed animal models. The objective was to analyze the existing animal models of fracture nonunion in long bones in vivo and to consider the possibility of their further use to evaluate the effectiveness of the use of modern biotechnologies for the in the management of fracture nonunion. It was found that the majority of developed animal models of atrophic long bone non-union were created using small animals, namely rats, mice, and rabbits. A more common method of modeling bone non-union is performing an osteotomy with the formation of a defect of different widths between the bone fragments and subsequent removal of the periosteum proximal and distal to the osteotomy site; damage to the endosteum or removal of bone marrow. Also, in such animal models, researchers use a silicone spacer, a polysulfone plate, or a latex-silicone foil to physically prevent fracture union. In these animal models, studies using mesenchymal stromal cells, platelet-rich plasma or bone morphogenetic protein-2 (BMP-2) have already been conducted for the management of non-union bone fractures. At the same time, the clinical results of the application of various biological therapies are ambiguous, which determines the conduct of further experimental studies, in particular, in vivo. However, there are disagreements about which in vivo modeling methods give a reproducible result and prevent bone union, which determines the need for further analysis of existing modeling tools for conducting research in this direction.

Translational Experimental Basis of Indirect Adenosine Receptor Agonist Stimulation for Bone Regeneration: A Review.

Bone regeneration remains a significant clinical challenge, often necessitating surgical approaches when healing bone defects and fracture nonunions. Within this context, the modulation of adenosine signaling pathways has emerged as a promising therapeutic option, encouraging osteoblast activation and tempering osteoclast differentiation. A literature review of the PubMed database with relevant keywords was conducted. The search criteria involved in vitro or in vivo models, with clear methodological descriptions. Only studies that included the use of indirect adenosine agonists, looking at the effects of bone regeneration, were considered relevant according to the eligibility criteria. A total of 29 articles were identified which met the inclusion and exclusion criteria, and they were reviewed to highlight the preclinical translation of adenosine agonists. While preclinical studies demonstrate the therapeutic potential of adenosine signaling in bone regeneration, its clinical application remains unrealized, underscoring the need for further clinical trials. To date, only large, preclinical animal models using indirect adenosine agonists have been successful in stimulating bone regeneration. The adenosine receptors (A1, A2A, A2B, and A3) stimulate various pathways, inducing different cellular responses. Specifically, indirect adenosine agonists act to increase the extracellular concentration of adenosine, subsequently agonizing the respective adenosine receptors. The agonism of each receptor is dependent on its expression on the cell surface, the extracellular concentration of adenosine, and its affinity for adenosine. This comprehensive review analyzed the multitude of indirect agonists currently being studied preclinically for bone regeneration, discussing the mechanisms of each agonist, their cellular responses in vitro, and their effects on bone formation in vivo.

Functional outcome of distraction osteogenesis in infected nonunion of the tibia

Abstract Background: The tibia is a bone located beneath the skin. Open fractures of the tibia, which involve significant soft tissue damage and bone loss, pose a challenge for trauma surgeons. The prevalence of long bone fractures is on the rise, attributed to the escalating number of road traffic accidents and other household mishaps, resulting in an increased occurrence of nonunion cases. Consequently, this study aims to evaluate the healing rates in long bone nonunion fractures and examine the complications associated with the treatment device. Managing infected tibial nonunions remains a formidable task for orthopedic surgeons. Materials and Methods: A retrospective study was conducted on 30 patients diagnosed with infected nonunion of tibial fractures treated with limb reconstruction systems (LRSs) in the Department of Orthopaedics at Vinayaka Missions Kirupananda Variyar Medical College and Hospital, Salem, Tamil Nadu, India. Inclusion criteria comprised patients aged between 20 and 55 years with tibial fractures failing to unite within 6 months, radiological evidence of nonunion, willingness to provide written informed consent and suitability for surgery. Results: The results revealed that most patients fell within the age group of 40–50 years, with an average age of 40.9 years in our study. Out of 30 patients, 17 were male and 13 were female. Regarding bony results, 20 patients (66.7%) exhibited excellent outcomes, 6 patients (20%) showed good results, 3 patients (10%) had fair outcomes, and 1 patient (3.3%) had poor outcomes. Functional outcomes showed that 20 patients (66.7%) experienced excellent results, 6 patients (20%) showed good outcomes, 3 patients (10%) had fair outcomes, and 1 patient (3.3%) had poor outcomes. Conclusion: This study concludes that the LRS fixator facilitates early ambulation, reducing the risk of osteoporosis, and soft tissue dystrophy. The average union time was 4 months, influenced by comminution, infection, nonunion type, smoking, and fracture pattern.

NOVEL PIEZOELECTRIC AND OSTEOCONDUCTIVE NANOFIBRES FOR BONE TISSUE ENGINEERING

The current procedures being applied in the clinical setting to address osteoporosis-related delayed union and nonunion bone fractures have been found to present mostly suboptimal outcomes. As a result, bone tissue engineering (BTE) solutions involving the development of implantable biomimetic scaffolds to replace damaged bone and support its regeneration are gaining interest. The piezoelectric properties of the bone tissue, which stem primarily from the significant presence of piezoelectric type I collagen fibrils in the tissue's extracellular matrix (ECM), play a key role in preserving the bone's homeostasis and provide integral assistance to the regeneration process. However, despite their significant potential, these properties of bone tend to be overlooked in most BTE-related studies. In order to bridge this gap in the literature, novel hydroxyapatite (HAp)-filled osteoinductive and piezoelectric poly(vinylidene fluoride-co-tetrafluoroethylene) (PVDF-TrFE) electrospun nanofibers were developed to replicate the bone's fibrous ECM composition and electrical features. Different HAp nanoparticle concentrations (1–10%, wt%) were tested to assess their effect on the physicochemical and biological properties of the resulting fibers. The fabricated scaffolds displayed biomimetic collagen fibril-like diameters, while also presenting mechanical features akin to type I collagen. The increase in HAp presence was found to enhance both surface and piezoelectric properties of the fibers, with an improvement in scaffold wettability and increase in β-phase nucleation (translating to increased piezoelectricity) being observed. The HAp-containing scaffolds also exhibited an augmented bioactivity, with a more comprehensive surface mineralization of the fibers being obtained for the scaffolds with the highest HAp concentrations. Improved osteogenic differentiation of seeded human mesenchymal stem/stromal cells was achieved with the addition of HAp, as confirmed by an increased ALP activity, calcium deposition and upregulated expression of key osteogenic markers. Overall, our findings highlight, for the first time, the potential of combining PVDF-TrFE and HAp to develop electroactive and osteoinductive nanofibers for BTE.Acknowledgements: The authors thank FCT for funding through the projects InSilico4OCReg (PTDC/EME-SIS/0838/2021), OptiBioScaffold (PTDC/EME-SIS/4446/2020) and BioMaterARISES (EXPL/CTM-CTM/0995/2021), the PhD scholarship (2022.10572.BD) and to the research institutions iBB (UIDB/04565/2020 and UIDP/04565/2020) and Associate Laboratory i4HB (LA/P/0140/2020).

Fully Reduced HMGB1 Enhances Nonunion Fracture Healing in Diabetic Rat Model

Category: Basic Sciences/Biologics; Diabetes Introduction/Purpose: Diabetes mellitus is a chronic metabolic disease that leads to serious complications including bone health and wound healing. Bone fractures commonly occur in diabetic patients, and are difficultly to heal due to prolonged inflammation, which leads to a higher risk of non-union. Fully reduced high mobility group box1 (frHMGB1) can play an important role in skeletal regeneration; however, the activity can be inhibited by Metformin; which is commonly used for the treatment of diabetes. The effect of frHMGB1 and Metformin on the bone fracture healing is largely unknown. In this study, we tested the hypothesis that frHMGB1 enhances healing in a nonunion bone fracture and Metformin inhibits the healing using a diabetic rat model. Methods: Diabetic fracture rat model was created by injection of streptozotocin into total 32 Sprague Dawley rats and confirmed by blood glucose levels.An incision was performed, tibia bones were fractured, followed by the muscle and skin wound closure.The rats were divided into four groups with 8 rats per group(Fig 1): Group-1 had no additional treatment;Group-2 were injected Metformin (IP, 160 mg/kg) daily;Group-3 were injected frHMGB1 into wound area (250 µg/kg) weekly;Group-4 were injected Metformin (IP, 160 mg/kg) daily and frHMGB1 into wound area (250 µg/kg) weekly. The rats were monitored postoperatively and sacrificed on postoperative day-28 and day-90. The blood samples were collected for HMGB1 & IL-1β.Tibia samples were also collected and examined by gross inspection, micro-CT images and histological analysis. Data was analyzed by One-way ANOVA followed by Fisher’s Least significance difference test. A p-value less than 0.05 was considered to be significantly different between the groups. Results: Metformin with frHMGB1 significantly decreased HMGB1 levels and decreased the enhanced expression of IL-1β compared to frHMGB1 alone. Micro-CT images showed completely healed at day-90 post-surgery in frHMGB1 rats while Metformin inhibited frHMGB1 enhanced bone fracture healing as evidenced by the gap in the fractured bone area(Fig 2). Histology analysis indicated that frHMGB1 enhanced fractured bone healing as evidenced by high density of the cells was found in the bone fracture area (Fig. 3). Safranin O and fast green staining along with Masson’s Trichrome staining confirmed the frHMGB1 local injection promoted fractured bone healing (Fig. 4) as evidenced by high quality bone tissue formation with collagen type I (red staining) and collagen type III (blue staining) in the fractured bone wound area. Conclusion: Fully reduced HMGB1 treatment enhanced healing in a nonunion diabetic rat model. The fracture site had high density of cells, quality bone tissue, and enhanced production of collagen I and III. However, Metformin inhibited frHMGB1-induced healing enhancement. In diabetic rats, nonunion bone fracture was present with evidence of inflammation showing elevated levels of HMGB1 and IL-1β.FrHMGB1 treatment enhanced healing of nonunion bone fracture by promoting cell proliferation and migration, limited HMGB1 concentration, increased collagen production. Although Metformin injection slowed down the bone fracture healing by inhibiting frHMGB1activity, it also blocked HMGB1 release and reduced the inflammation caused by HMGB1.

Treatment of Non-Union with Bone Loss in Femur Fracture Using Non-vascularized Fibular Graft: A Case Report

Abstract: Fibula is a very versatile source of autogenous graft and has been used for decades in the field of limb reconstruction. Bony defects of the lower extremity are usually the result of high-energy trauma, tumor resection, or severe sepsis. Non-vascularized fibular graft (NVFG) is useful in the reconstruction of skeletal defects, especially in cases of scarred and avascular recipient sites, or in patients with combined bone and soft tissue defects. This study aimed to assess the effectiveness of NVFG in the management of non-union bone fracture. We reported a 16-years-old male with non-union femur fracture. Debridements were applied at the first time of admission to the hospital. Open reduction of fracture with internal femur fixation. Fibula bone was extracted as the donor of vascularized graft for the bone loss. After two years of follow-up, the patient acquired his motor functions back well, and was able to carry out daily activities as expected. In conclusion, taking together the repair and reconstruction of non-union bone in the lower extremity with NVFG and internal fixation is an effective and important option for treating non-union femoral fracture. NVFG osteosynthesis has encouraging results in such instances. It is technically less demanding, simple, and can be performed in almost all centers where image intensifier is available. Keywords: bone fracture; non-vascularized fibular graft; reconstructive microsurgery; femoral non-union

Surgical repair of large segmental bone loss with the induced membrane technique: patient reported outcomes are comparable to nonunions without bone loss.

To compare the outcomes of patients with segmental bone loss who underwent repair with the induced membrane technique (IMT) with a matched cohort of nonunion fractures without bone loss. Retrospective analysis on prospectively collected data. Academic medical center. Two cohorts of patients, those with upper and lower extremity diaphyseal large segmental bone loss and those with ununited fractures, were enrolled prospectively between 2013 and 2020. Sixteen patients who underwent repair of 17 extremities with segmental diaphyseal or meta-diaphyseal bone defects treated with the induced membrane technique were identified, and matched with 17 patients who were treated for 17 fracture nonunions treated without an induced membrane. Sixteen of the bone defects treated with the induced membrane technique were due to acute bone loss, and the other was a chronic aseptic nonunion. Healing rate, time to union, functional outcome scores using the Short Musculoskeletal Functional Assessment (SMFA) and pain assessed by the Visual Analog Scale (VAS). The initial average defect size for patients treated with the induced membrane technique was 8.85cm. Mean follow-up times were similar with 17.06 ± 10.13months for patients treated with the IMT, and 20.35 ± 16.68. months for patients treated without the technique. Complete union was achieved in 15/17 (88.2%) of segmental bone loss cases treated with the IMT and 17/17 (100%) of cases repaired without the technique at the latest follow up visit. The average time to union for patients treated with the induced membrane technique was 13.0 ± 8.4months and 9.64 ± 4.7months for the matched cohort. There were no significant differences in reported outcomes measured by the SMFA or VAS. Patients treated with the induced membrane technique required more revision surgeries than those not treated with an induced membrane. Outcomes following treatment of acute bone loss from the diaphysis of long bones with the induced membrane technique produces clinical and radiographic outcomes similar to those of long bone fracture nonunions without bone loss that go on to heal. III.

EE22 Risk Factors and Healthcare Costs Associated with Long Bone Fracture Non-Union – A US Claims Database Analysis

Non-union is a common complication following long bone fractures, often requiring significant incremental healthcare resources. The payer cost of long bone non-union in patients with or without concurrent infection is not well documented. Our study evaluated 2-year incremental healthcare costs of non-union in patients with fractures.

CO152 Risk Factors Associated with Long Bone Fracture Non-Union – A US Claims Database Analysis

Few contemporary long bone non-union analyses have been documented. Our study was designed to provide a current understanding of non-union rates and risk factors for long bone fractures.

Bone marrow-derived dedifferentiated fat cells exhibit similar phenotype as bone marrow mesenchymal stem cells with high osteogenic differentiation and bone regeneration ability

BackgroundMesenchymal stem cells (MSCs) are known to have different differentiation potential depending on the tissue of origin. Dedifferentiated fat cells (DFATs) are MSC-like multipotent cells that can be prepared from mature adipocytes by ceiling culture method. It is still unknown whether DFATs derived from adipocytes in different tissue showed different phenotype and functional properties. In the present study, we prepared bone marrow (BM)-derived DFATs (BM-DFATs), BM-MSCs, subcutaneous (SC) adipose tissue-derived DFATs (SC-DFATs), and adipose tissue-derived stem cells (ASCs) from donor-matched tissue samples. Then, we compared their phenotypes and multilineage differentiation potential in vitro. We also evaluated in vivo bone regeneration ability of these cells using a mouse femoral fracture model.MethodsBM-DFATs, SC-DFATs, BM-MSCs, and ASCs were prepared from tissue samples of knee osteoarthritis patients who received total knee arthroplasty. Cell surface antigens, gene expression profile, and in vitro differentiation capacity of these cells were determined. In vivo bone regenerative ability of these cells was evaluated by micro-computed tomography imaging at 28 days after local injection of the cells with peptide hydrogel (PHG) in the femoral fracture model in severe combined immunodeficiency mice.ResultsBM-DFATs were successfully generated at similar efficiency as SC-DFATs. Cell surface antigen and gene expression profiles of BM-DFATs were similar to those of BM-MSCs, whereas these profiles of SC-DFATs were similar to those of ASCs. In vitro differentiation analysis revealed that BM-DFATs and BM-MSCs had higher differentiation tendency toward osteoblasts and lower differentiation tendency toward adipocytes compared to SC-DFATs and ASCs. Transplantation of BM-DFATs and BM-MSCs with PHG enhanced bone mineral density at the injection sites compared to PHG alone in the mouse femoral fracture model.ConclusionsWe showed that phenotypic characteristics of BM-DFATs were similar to those of BM-MSCs. BM-DFATs exhibited higher osteogenic differentiation potential and bone regenerative ability compared to SC-DFATs and ASCs. These results suggest that BM-DFATs may be suitable sources of cell-based therapies for patients with nonunion bone fracture.

Exosomes Derived from Adipose Stem Cells Enhance Bone Fracture Healing via the Activation of the Wnt3a/β-Catenin Signaling Pathway in Rats with Type 2 Diabetes Mellitus.

Nonunion and delayed union are common complications of diabetes mellitus that pose a serious health threat to people. There are many approaches that have been used to improve bone fracture healing. Recently, exosomes have been regarded as promising medical biomaterials for improving fracture healing. However, whether exosomes derived from adipose stem cells can promote bone fracture healing in diabetes mellitus remains unclear. In this study, adipose stem cells (ASCs) and exosomes derived from adipose stem cells (ASCs-exos) are isolated and identified. Additionally, we evaluate the in vitro and in vivo effects of ASCs-exos on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and bone repair and the regeneration in a rat model of nonunion via Western blotting, immunofluorescence assay, ALP staining, alizarin red staining, radiographic examination and histological analysis. Compared with controls, ASCs-exos promoted BMSC osteogenic differentiation. Additionally, the results of Western blotting, radiographic examination and histological analysis show that ASCs-exos improve the ability for fracture repair in the rat model of nonunion bone fracture healing. Moreover, our results further proved that ASCs-exos play a role in activating the Wnt3a/β-catenin signaling pathway, which facilitates the osteogenic differentiation of BMSCs. All these results show that ASCs-exos enhance the osteogenic potential of BMSCs by activating the Wnt/β-catenin signaling pathway, and also facilitate the ability for bone repair and regeneration in vivo, which provides a novel direction for fracture nonunion in diabetes mellitus treatment.

Clinical Study on the Treatment of Long Bone Fracture Non-Union with Extracorporeal Shock Wave Therapy Combined with Platelet-Rich Plasma

Objective: The objective of the study was to evaluate of the therapeutic efficacy of extracorporeal shock wave therapy (ESWT) combined with platelet-rich plasma (PRP) injection in patients with long bone fracture non-union. Material and Methods: A total of 36 patients identified with long bone fracture non-union treated from September 2020 to September 2023 were enrolled into this study. Employing a random number table method, they were randomly divided into three groups, with 12 cases in each group. Based on the treatment modality, the groups were categorized as the ESWT group, PRP group, and combination ESWT + PRP group. Routine radiographs and musculoskeletal ultrasound were obtained before treatment and at 3-, 6-, and 9-month post-treatment intervals to observe for bone callus formation and assess fracture line imaging scores with the aim to evaluate the treatment efficacy of each group. Results: With the extension of treatment time, the bone callus and fracture line imaging scores of the three groups gradually increased (P < 0.05). At 3-, 6-, and 9-month post-treatment, the scores of the ESWT combined with the PRP group were significantly better than those of the singular ESWT group and PRP group, and the differences were statistically significant (P < 0.05). Conclusion: Therapy with singular ESWT, singular PRP, and combination ESWT + PRP has demonstrated effective improvement in fracture healing for patients with long bone fracture non-union. The synergistic effects of combination therapy were more significant, surpassing the efficacy of singular ESWT or PRP applications. The combined use of ESWT and PRP represents a safe and promising alternative treatment for long-bone fracture non-union, making it a compelling choice in the context of fracture healing. Keywords: Extracorporeal shock wave therapy, Platelet-rich plasma, Non-union of fracture.

The Effect of Argon Plasma Surface Treatment on Poly(lactic-co-glycolic acid)/Collagen-Based Biomaterials for Bone Tissue Engineering.

Nonunion bone fractures can impact the quality of life and represent a major economic burden. Scaffold-based tissue engineering has shown promise as an alternative to bone grafting. Achieving desirable bone reconstruction requires appropriate surface properties, together with optimizing the internal architecture of 3D scaffolds. This study presents the surface modification of poly(lactic-co-glycolic acid) (PLGA), collagen, and PLGA-collagen via an argon plasma treatment. Argon plasma can modify the surface chemistry and topography of biomaterials and improve in vivo integration. Solvent-cast films were prepared using 1,1,1,3,3,3-hexafluoro-2-propanol and characterized via differential scanning calorimetry, thermogravimetric analysis, contact angle measurement, and critical surface tension analysis. For PLGA films, the water contact angle dropped from 70° to 42°, whereas the diiodomethane contact angle reduced from 53° to 32° after the plasma treatment. A set of PLGA-collagen formulations were loaded with nanohydroxyapatite (nHA) and polyethylene glycol (PEG) to enhance their osteoconductivity and hydrophilicity. Then, 3D scaffolds were fabricated using a 3D Bioplotter and characterized via Fourier-transform infrared (FTIR) spectroscopy. A bicinchoninic acid assay (BCA) was used to compare the protein release from the untreated and plasma-treated scaffolds into phosphate-buffered saline (PBS). The plasma-treated scaffolds had a lower protein release, and the difference compared to the untreated scaffolds was statistically significant.

Assessing the outcomes of treatment of infected long bone nonunion fracture with distraction osteogenesis using the linear rail system

Background: The treatment of bone gap due to an infected nonunion and open infected fracture is very interesting and controversial topic in orthopedics due to factors such as poor vascularity of surrounding tissue. Distraction osteogenesis is a method of producing unlimited quantities of living bone directly from a special osteotomy site. This study was performed to assess the role of bone transport by rail fixator (Pitkar, India) in treatment of bone gap in long bones due to infected long bones nonunion fracture.Methods: Patients folders were perused, proforma formed and data collected partly from the folder and partly filled by the enrollee. Information as regards biodata, clinicoradiological characteristics, Outcome of management were taken. Patient also filled the quality of life questionnaire. Data analyzed using SPSS version 23 and represented as charts and tables.Variables were compared and conclusions drawn’.Results: 85.7% were males. M:F ratio 6:1. Ages 32-40 were the most operated (50%). Limb lengthening was done in 53.6% while bone transport in 39.3%.the tibia was the bone most operated in 85.7% of cases. Most distractions were less than 7cm (50%).Pin tract infection was the most common problem found in 5 out of the 28enrollees, most had no problems.Limb length discrepancy was found in 7.1%.There were associations found between complication and aim of surgery and also with length gained.Conclusion: The linear rail system is vasatile in the treatment of infected long bone nonunion fractures with excellent result, little complications and a very satisfactory quality of life.

Bioactive glass-collagen/poly (glycolic acid) scaffold nanoparticles exhibit improved biological properties and enhance osteogenic lineage differentiation of mesenchymal stem cells.

Today’s using tissue engineering and suitable scaffolds have got attention to increase healing of non-union bone fractures. In this study, we aimed to prepare and characterize scaffolds with functional and mechanical properties suitable for bone regeneration. Porous scaffolds containing collagen-poly glycolic acid (PGA) blends and various quantities of bioactive glass (BG) 45S5 were fabricated. Scaffolds with different compositions (BG/collagen-PGA ratios (w/w): 0/100; 40/60; 70/30) were characterized for their morphological properties, bioactivity, and mechanical behavior. Then, biocompatibility and osteogenic differentiation potential of the scaffolds were analyzed by seeding mesenchymal stem cells (MSCs). Scaffolds made with collagen-PGA combined with the BG (45S5) were found to have interconnected pores (average pore diameter size 75–115 µm) depending on the percentage of the BG added. Simulated body fluid (SBF) soaking experiments indicated the stability of scaffolds in SBF regardless of their compositions, while the scaffolds retained their highly interconnected structure. The elastic moduli, cell viability, osteogenic differentiation of the BG/collagen-PGA 40/60 and 70/30 scaffolds were superior to the original BG/collagen-PGA (0/100). These results suggest that BG incorporation enhanced the physical stability of our collagen-PGA scaffold previously reported. This new scaffold composition provides a promising platform to be used as a non-toxic scaffold for bone regeneration and tissue engineering.

Comparison of synthetic ceramic products formulated with autologous blood coagulum containing rhBMP6 for induction of bone formation.

Osteogrow, an osteoinductive device containing recombinant human Bone Morphogenetic Protein 6 (rhBMP6) in autologous blood coagulum, is a novel therapeutic solution for bone regeneration. This study aimed to evaluate different commercially available calcium phosphate synthetic ceramic particles as a compression-resistant matrix (CRM) added to Osteogrow implants to enhance their biomechanical properties. Osteogrow implants with the addition of Vitoss, ChronOs, BAM, and Dongbo ceramics (Osteogrow-C, where C stands for ceramics) were evaluated in the rodent subcutaneous ectopic bone formation assay. Osteogrow-C device was prepared as follows: rhBMP6 was added to blood, and blood was mixed with ceramics and left to coagulate. Osteogrow-C was implanted subcutaneously in the axillary region of Sprague-Dawley rats and the outcome was analyzed 21days following implantation using microCT, histology, morphometric analyses, and immunohistochemistry. Osteogrow-C implants with all tested ceramic particles induced the formation of the bone-ceramic structure containing cortical bone, the bone between the particles, and bone at the ceramic surfaces. The amount of newly formed bone was significant in all experimental groups; however, the highest bone volume was measured in Osteogrow-C implants with highly porous Vitoss ceramics. The trabecular number was highest in Osteogrow-C implants with Vitoss and ChronOs ceramics while trabeculae were thicker in implants containing BAM and Dongbo ceramics. The immunological response and inflammation were comparable among ceramic particles evaluated in this study. Osteogrow-C bone regenerative device was effective with a broad range of commercially available synthetic ceramics providing a promising therapeutic solution for the regeneration of long bone fracture nonunion, large segmental defects, and spinal fusion surgeries.

Nonsteroidal anti-inflammatory drugs for pain relief in case of injuries: Is there a risk of bone metabolism disorders and nonunion of bone fractures?

According to experimental studies, nonsteroidal anti-inflammatory drugs (NSAIDs) can affect the healing of bone tissue after fractures. The significance of this effect of NSAIDs for real clinical practice is the subject of discussion. We analyzed publications on the problem of nonunion or development of fractures against the background of taking NSAIDs presented in the PubMed and MEDLINE system. From 1976 to 2021, 75 papers on this topic were published, of which 19 were observational, cohort and randomized controlled trials, as well as case-control studies, 4 meta-analyses. According to meta-analyses, which included from 6 to 16 studies, there was an association between taking NSAIDs and nonunion of bones after fractures or postoperative trauma: the odds ratio ranged from 2.07 (95% CI: 1.19–3.61) to 5.27 (95% CI: 2.34–11.88). A number of large studies confirm an increased risk of nonunion of fractures and the development of “marching” fractures in patients treated with NSAIDs. The risk of nonunion was increased when using NSAIDs for more than 2 weeks and in high doses. With short-term use of NSAIDs (less than 2 weeks) and the use of these drugs in pediatric practice, the frequency of bone tissue repair disorders did not increase.

The interdependent relationship between the nitric oxide signaling pathway and primary cilia in pulse electromagnetic field-stimulated osteoblastic differentiation.

Pulsed electromagnetic fields (PEMFs) have long been recognized being safe and effective in treating bone fracture nonunion and osteoporosis. However, the mechanism of osteogenic action of PEMFs is still unclear. While primary cilia are reported to be a sensory organelle for PEMFs, and nitric oxide (NO) plays an indispensable role in osteogenic effect of PEMFs, the relationship between NO and primary cilia is unknown. In this study, effects of treatment with 50Hz 0.6mT PEMFs on osteogenic differentiation and mineralization, NO secretion, and ciliary location of specific proteins were examined in rat calvarial osteoblasts (ROBs) with normal or abrogated primary cilia. It was found that PEMFs stimulated the osteogenic differentiation by activating the NOS/NO/sGC/cGMP/PKG signaling pathway, which need the existence of primary cilia. All components of the signaling pathway including iNOS, eNOS, sGC, PKG-1, and PKG-2 were localized to primary cilia, and eNOS was phosphorylated inside the primary cilia. Besides, primary cilia were elongated significantly by PEMF treatment and changed dynamically with the activation NO/cGMP pathway. When the pathway was blocked by L-NAME, PEMFs could no longer elongate the primary cilia and stimulate the osteoblastic differentiation. Thus, this study for the first time observed activation of the NO/cGMP signaling pathway in ciliary compartment of osteoblasts, and PEMFs could not stimulate the osteoblastic differentiation if the NO signaling pathway was blocked or the ciliogenesis was inhibited. Our findings indicate the interdependent relationship between NO and primary cilia in the PEMF-promoted osteogenesis.

Bioinformatics-Guided Analysis Uncovers AOX1 as an Osteogenic Differentiation-Relevant Gene of Human Mesenchymal Stem Cells.

Background: The available therapeutic options of bone defects, fracture nonunion, and osteoporosis remain limited, which are closely related to the osteogenic differentiation of bone marrow–derived mesenchymal stem cells (BMSCs). Thus, there remains an urgent demand to develop a prediction method to infer osteogenic differentiation–related genes in BMSCs. Method: We performed differential expression analysis between hBMSCs and osteogenically induced samples. Association analysis, co-expression analysis, and PPI analysis are then carried out to identify potential osteogenesis-related regulators. GO enrichment analysis and GSEA are performed to identify significantly enriched pathways associated with AOX1. qRT-PCR and Western blotting were employed to investigate the expression of genes on osteogenic differentiation, and plasmid transfection was used to overexpress the gene AOX1 in hBMSCs. Result: We identified 25 upregulated genes and 17 downregulated genes. Association analysis and PPI network analysis among these differentially expressed genes show that AOX1 is a potential regulator of osteogenic differentiation. GO enrichment analysis and GSEA show that AOX1 is significantly associated with osteoblast-related pathways. The experiments revealed that AOX1 level was higher and increased gradually in differentiated BMSCs compared with undifferentiated BMSCs, and AOX1 overexpression significantly increased the expression of osteo-specific genes, thereby clearly indicating that AOX1 plays an important role in osteogenic differentiation. Moreover, our method has ability in discriminating genes with osteogenic differentiation properties and can facilitate the process of discovery of new osteogenic differentiation–related genes. Conclusion: These findings collectively demonstrate that AOX1 is an osteogenic differentiation-relevant gene and provide a novel method established with a good performance for osteogenic differentiation-relevant genes prediction.

Effect of Intramedullary Nailing Patterns on Interfragmentary Strain in a Mouse Femur Fracture: A Parametric Finite Element Analysis.

Delayed long bone fracture healing and nonunion continue to be a significant socioeconomic burden. While mechanical stimulation is known to be an important determinant of the bone repair process, understanding how the magnitude, mode, and commencement of interfragmentary strain (IFS) affect fracture healing can guide new therapeutic strategies to prevent delayed healing or nonunion. Mouse models provide a means to investigate the molecular and cellular aspects of fracture repair, yet there is only one commercially available, clinically-relevant, locking intramedullary nail (IMN) currently available for studying long bone fractures in rodents. Having access to alternative IMNs would allow a variety of mechanical environments at the fracture site to be evaluated, and the purpose of this proof-of-concept finite element analysis study is to identify which IMN design parameters have the largest impact on IFS in a murine transverse femoral osteotomy model. Using the dimensions of the clinically relevant IMN as a guide, the nail material, distance between interlocking screws, and clearance between the nail and endosteal surface were varied between simulations. Of these parameters, changing the nail material from stainless steel (SS) to polyetheretherketone (PEEK) had the largest impact on IFS. Reducing the distance between the proximal and distal interlocking screws substantially affected IFS only when nail modulus was low. Therefore, IMNs with low modulus (e.g., PEEK) can be used alongside commercially available SS nails to investigate the effect of initial IFS or stability on fracture healing with respect to different biological conditions of repair in rodents.