Equal rates of bone healing and reduced surgical time with iliac crest allograft compared to autograft in medial opening wedge high tibial osteotomy: a randomized controlled clinical trial.

INTRODUCTION: Iliac crest autograft is frequently used to fill in bone defects after osteotomies. Nonetheless, surgery for bone autograft procurement is associated with morbidity and pain at the donor site. Alternatives to it have been explored, but there is no consensus to guide their application as a routine practice in several orthopedic procedures. Thus, this study was designed to compare the efficacy and safety between iliac crest autograft and allograft in medial opening wedge high tibial osteotomy. MATERIALS AND METHODS: Forty-seven patients with a symptomatic unilateral genu varum and an indication for high tibial osteotomy were randomly assigned to receive either autograft or allograft to fill the osteotomy site. Operative time, bone healing, and complication rates (delayed union, nonunion, superficial and deep infection, loss of correction, and hardware failure) were recorded after a one-year follow-up. Data were expressed as Mean ± Standard Deviation and considered statistically significant when p < 0.05. RESULTS: The time to radiologic union was similar between both groups (Allograft: 2.38 ± 0.97 months vs. Autograft: 2.45 ± 0.91 months; p = 0.79). Complication rates were also similar in both groups, with one infection in the allograft group and two in the autograft group, two delayed unions in the allograft group, and three in the autograft group. The operative time differed by 11 min between the groups, being lower in the allograft group (Allograft: 65.4 ± 15.1 min vs. Autograft: 76.3 ± 15.2 min; p = 0.02). CONCLUSION: Iliac crest allografts can be safely and effectively used in medial opening wedge high tibial osteotomy as it promotes the same rates of bone union as those achieved by autologous grafts, with the benefits of a shorter operative time. TRIAL REGISTRATION NUMBER: U1111-1280-0637 1 December 2022, retrospectively registered.

Requirement of Pdgfrα+ cells for calvarial bone repair.

Platelet-derived growth factor receptor α (PDGFRα) is often considered as a general marker of mesenchymal cells and fibroblasts, but also shows expression in a portion of osteoprogenitor cells. Within the skeleton, Pdgfrα+ mesenchymal cells have been identified in bone marrow and periosteum of long bones, where they play a crucial role in participating in fracture repair. A similar examination of Pdgfrα+ cells in calvarial bone healing has not been examined. Here, we utilize Pdgfrα-CreERTM;mT/mG reporter animals to examine the contribution of Pdgfrα+ mesenchymal cells to calvarial bone repair through histology and single-cell RNA sequencing (scRNA-Seq). Results showed that Pdgfrα+ mesenchymal cells are present in several cell clusters by scRNA-Seq, and by histology a dramatic increase in Pdgfrα+ cells populated the defect site at early timepoints to give rise to healed bone tissue overtime. Notably, diphtheria toxin-mediated ablation of Pdgfrα reporter+ cells resulted in significantly impaired calvarial bone healing. Our findings suggest that Pdgfrα-expressing cells within the calvarial niche play a critical role in the process of calvarial bone repair.

Comparative effect of skeletal stem cells versus bone marrow mesenchymal stem cells on rotator cuff tendon-bone healing.

Background: Bone marrow mesenchymal stem cells (BMSCs) have immense potential in applications for the enhancement of tendon-bone (T-B) healing. Recently, it has been well-reported that skeletal stem cells (SSCs) could induce bone and cartilage regeneration. Therefore, SSCs represent a promising choice for cell-based therapies to improve T-B healing. In this study, we aimed to compare the therapeutic potential of SSCs and BMSCs for tendon-bone healing. Methods: SSCs and BMSCs were isolated by flow cytometry, and their proliferation ability was measured by CCK-8 assay. The osteogenic, chondrogenic, and adipogenic gene expression in cells was detected by quantitative real-time polymerase chain reaction (qRT-PCR). C57BL/6 mice underwent unilateral supraspinatus tendon detachment and repair, and the mice were then randomly allocated to 4 groups: control group (tendon-bone interface without any treatment), hydrogel group (administration of blank hydrogel into the tendon-bone interface), hydrogel + BMSCs group (administration of hydrogel with BMSCs into the tendon-bone interface), and hydrogel + SSCs group (administration of hydrogel with SSCs into the tendon-bone interface). Histological staining, Micro-computed tomography (Micro-CT) scanning, biomechanical testing, and qRT-PCR were performed to assay T-B healing at 4 and 8 weeks after surgery. Results: SSCs showed more cell proportion, exhibited stronger multiplication capacity, and expressed higher osteogenic and chondrogenic markers and lower adipogenic markers than BMSCs. In vivo assay, the SSCs group showed a better-maturated interface which was characterized by richer chondrocytes and more proteoglycan deposition, as well as more newly formed bone at the healing site and increased mechanical properties when compared to other there groups. qRT-PCR analysis revealed that the healing interface in the SSCs group expressed more transcription factors essential for osteogenesis and chondrogenesis than the interfaces in the other groups. Conclusions: Overall, the results demonstrated the superior therapeutic potential of SSCs over BMSCs in tendon-bone healing. The translational potential of this article: This current study provides valuable insights that SSCs may be a more effective cell therapy for enhancing T-B healing compared to BMSCs.

Titanium versus plasma electrolytic oxidation surface-modified magnesium miniplates in a forehead secondary fracture healing model in sheep.

Magnesium as a biodegradable material offers promising results in recent studies of different maxillo-facial fracture models. To overcome adverse effects caused by the fast corrosion of pure magnesium in fluid surroundings, various alloys, and surface modifications are tested in animal models. In specified cases, magnesium screws already appeared for clinical use in maxillofacial surgery. The present study aims to compare the bone healing outcome in a non-load-bearing fracture scenario of the forehead in sheep when fixed with standard-sized WE43 magnesium fixation plates and screws with plasma electrolytic oxidation (PEO) surface modification in contrast to titanium osteosynthesis. Surgery was performed on 24 merino mix sheep. The plates and screws were explanted en-bloc with the surrounding tissue after four and twelve weeks. The outcome of bone healing was investigated with micro-computed tomography, histological, immunohistological, and fluorescence analysis. There was no significant difference between groups concerning the bone volume, bone volume/ total volume, and newly formed bone in volumetric and histological analysis at both times of investigation. The fluorescence analysis revealed a significantly lower signal in the magnesium group after one week, although there was no difference in the number of osteoclasts per mm2. The magnesium group had significantly fewer vessels per mm2 in the healing tissue. In conclusion, the non-inferiority of WE43-based magnesium implants with PEO surface modification was verified concerning fracture healing under non-load-bearing conditions in a defect model. STATEMENT OF SIGNIFICANCE: Titanium implants, the current gold standard of fracture fixation, can lead to adverse effects linked to the implant material and often require surgical removal. Therefore, degradable metals like the magnesium alloy WE43 with plasma electrolytic oxidation (PEO) surface modification gained interest. Yet, miniplates of this alloy with PEO surface modification have not been examined in a fracture defect model of the facial skeleton in a large animal model. This study shows, for the first time, the non-inferiority of magnesium miniplates compared to titanium miniplates. In radiological and histological analysis, bone healing was undisturbed. Magnesium miniplates can reduce the number of interventions for implant removal, thus reducing the risk for the patient and minimizing the costs.

Enhancing tendon-bone integration and healing with advanced multi-layer nanofiber-reinforced 3D scaffolds for acellular tendon complexes.

Advancements in tissue engineering are crucial for successfully healing tendon-bone connections, especially in situations like anterior cruciate ligament (ACL) restoration. This study presents a new and innovative three-dimensional scaffold, reinforced with nanofibers, that is specifically intended for acellular tendon complexes. The scaffold consists of a distinct layered arrangement comprising an acellular tendon core, a middle layer of polyurethane/type I collagen (PU/Col I) yarn, and an outside layer of poly (L-lactic acid)/bioactive glass (PLLA/BG) nanofiber membrane. Every layer is designed to fulfill specific yet harmonious purposes. The acellular tendon core is a solid structural base and a favorable environment for tendon cell functions, resulting in considerable tensile strength. The central PU/Col I yarn layer is vital in promoting the tendinogenic differentiation of stem cells derived from tendons and increasing the expression of critical tendinogenic factors. The external PLLA/BG nanofiber membrane fosters the process of bone marrow mesenchymal stem cells differentiating into bone cells and enhances the expression of markers associated with bone formation. Our scaffold's biocompatibility and multi-functional design were confirmed through extensive in vivo evaluations, such as histological staining and biomechanical analyses. These assessments combined showed notable enhancements in ACL repair and healing. This study emphasizes the promise of multi-layered nanofiber scaffolds in orthopedic tissue engineering and also introduces new possibilities for the creation of improved materials for regenerating the tendon-bone interface.

How to explain the beneficial effects of leukocyte- and platelet-rich fibrin.

The survival of an organism relies on its ability to repair the damage caused by trauma, toxic agents, and inflammation. This process involving cell proliferation and differentiation is driven by several growth factors and is critically dependent on the organization of the extracellular matrix. Since autologous platelet concentrates (APCs) are fibrin matrices in which cells, growth factors, and cytokines are trapped and delivered over time, they are able to influence that response at different levels. The present review thoroughly describes the molecular components present in one of these APCs, leukocyte- and platelet-rich fibrin (L-PRF), and summarizes the level of evidence regarding the influence of L-PRF on anti-inflammatory reactions, analgesia, hemostasis, antimicrobial capacity, and its biological mechanisms on bone/soft tissue regeneration.

Clinically relevant doses of tiludronate do not affect bone remodelling in pasture-exercised horses.

BACKGROUND: Bisphosphonates are widely used in equine athletes to reduce lameness associated with skeletal disorders. Widespread off-label use has led to concern regarding potential negative effects on bone healing, but little evidence exists to support or refute this. OBJECTIVES: To investigate the influence of clinically relevant doses of tiludronate on bone remodelling and bone healing. STUDY DESIGN: Randomised, controlled in vivo experiments. METHODS: Each horse had a single tuber coxae biopsied (Day 0), then were divided into a treatment (IV tiludronate) or control (IV saline) group. Treatments were administered 30 and 90 days following initial biopsy. Biopsy of the tuber coxae was repeated on Day 60 to evaluate bone healing following a single treatment. Oxytetracycline was administered on Days 137 and 147 to label bone formation. The contralateral tuber coxae was biopsied on Day 150 to evaluate effects of repeated treatment. Bone biopsies were evaluated with micro-computed tomography and/or dynamic histomorphometry using standard techniques. RESULTS: Nineteen horses completed the study, with no complications following the biopsies and treatments. No significant differences in the trabecular bone parameters or bone formation rate were observed between treatment groups. MAIN LIMITATIONS: The use of a first-generation bisphosphonate may mean some effects of these drugs are underrepresented using this model. The results pertain to the tuber coxae and may not reflect injury or the healing response that occurs in long bones in training or racing. CONCLUSIONS: In this model, tiludronate did not affect normal bone remodelling in the horse, despite repeat dosages.

Electrical impedance detects early stages of bone healing: An in vivo explanatory study of tibial fractures in rabbits.

Purpose: Healing after bone fracture is assessed by clinical examination and frequent radiographs, which expose patients to radiation and lack standardisation. This study aimed to explore electrical impedance patterns during bone healing using electrical impedance spectroscopy in 18 rabbits subjected to tibial fracture stabilised with an external fixator. Methods: Impedance was measured daily across the fracture site at a frequency range of 5 Hz to 1 MHz. Biweekly radiographs were analysed using modified anterior-posterior (AP) radiographic union score of the tibia (RUST). The animals were divided into three groups with different follow-up times: 1, 3 and 6 weeks for micro-computer tomography and mechanical testing. Results: A decreasing trend in impedance was observed over time for all rabbits at lower frequencies. Impedance closest to 5 Hz showed a statistically significant decrease over time, with greatest decrease occurring during the first 7 postoperative days. At 5 Hz, a statistically significant correlation was found between impedance and the modified AP RUST score and between impedance and bone volume fraction. Conclusions: This study showed that the electrical impedance can be measured in vivo at a distance from the fracture site with a consistent change in impedance over time and revealed significant correlation between increasing radiographic union score and decreasing impedance. Level of Evidence: Not applicable.

Teriparatide Does not Have Beneficial Effects on Bone Healing in Complete Atypical Femur Fractures.

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.

Mussel inspired 3D elastomer enabled rapid calvarial bone regeneration through recruiting more osteoprogenitors from the dura mater.

Currently, the successful healing of critical-sized calvarial bone defects remains a considerable challenge. The immune response plays a key role in regulating bone regeneration after material grafting. Previous studies mainly focused on the relationship between macrophages and bone marrow mesenchymal stem cells (BMSCs), while dural cells were recently found to play a vital role in the calvarial bone healing. In this study, a series of 3D elastomers with different proportions of polycaprolactone (PCL) and poly(glycerol sebacate) (PGS) were fabricated, which were further supplemented with polydopamine (PDA) coating. The physicochemical properties of the PCL/PGS and PCL/PGS/PDA grafts were measured, and then they were implanted as filling materials for 8 mm calvarial bone defects. The results showed that a matched and effective PDA interface formed on a well-proportioned elastomer, which effectively modulated the polarization of M2 macrophages and promoted the recruitment of dural cells to achieve full-thickness bone repair through both intramembranous and endochondral ossification. Single-cell RNA sequencing analysis revealed the predominance of dural cells during bone healing and their close relationship with macrophages. The findings illustrated that the crosstalk between dural cells and macrophages determined the vertical full-thickness bone repair for the first time, which may be the new target for designing bone grafts for calvarial bone healing.

Exploring Ascorbic Acid's Role in Orthopedic Practices: Present Theories, Innovative Approaches, and Prospects.

In the human body, ascorbic acid (AA) is known for its potent antioxidant and reducing properties and also plays a vital role in supporting the growth of bones and cartilage. It has been used extensively in orthopedic surgery. Ongoing studies under the umbrella of ascorbic acid research investigate its impact on bone and tendon physiology, as well as its influence on joint replacement and postoperative pain. The majority of both laboratory and human studies link the usage of ascorbic acid to enhanced bone health and improved tendon healing. Recent literature suggest that ascorbic acid administration may have a positive impact on the outcome of orthopedic procedures. On the other hand, controversy exists regarding the efficacy of ascorbic acid in reducing the incidence of complex regional pain syndrome. In brief, the effectiveness of ascorbic acid in enhancing orthopedic procedure outcomes remains a subject of ongoing investigation. Although certain studies have hinted at the potential positive influence of ascorbic acid on these outcomes, further research is required to validate its effectiveness and ascertain the ideal dosage and method of administration for maximizing its anticipated advantages. To establish the efficacy of ascorbic acid in improving orthopedic procedure outcomes, rigorous human trials of high quality are imperative. The aim of this review was to provide an overview of ascorbic acid's utilization in orthopedic practices and to pinpoint prospective areas for future research.

Molecular mechanisms of EGCG-CSH/n-HA/CMC in promoting osteogenic differentiation and macrophage polarization.

2. This research investigates the impact of the EGCG-CSH/n-HA/CMC composite material on bone defect repair, emphasizing its influence on macrophage polarization and osteogenic differentiation of BMSCs. Comprehensive evaluations of the composite's physical and chemical characteristics were performed. BMSC response to the material was tested in vitro for proliferation, migration, and osteogenic potential. An SD rat model was employed for in vivo assessments of bone repair efficacy. Both transcriptional and proteomic analyses were utilized to delineate the mechanisms influencing macrophage behavior and stem cell differentiation. The material maintained excellent structural integrity and significantly promoted BMSC functions critical to bone healing. In vivo results confirmed accelerated bone repair, and molecular analysis highlighted the role of macrophage M2 polarization, particularly through changes in the SIRPA gene and protein expression. EGCG-CSH/n-HA/CMC plays a significant role in enhancing bone repair, with implications for macrophage and BMSC function. Our findings suggest that targeting SIRPA may offer new therapeutic opportunities for bone regeneration.

The use of hyperbaric oxygen for avascular necrosis of the femoral head and femoral condyle: a single centre's experience over 30 years.

Introduction: Avascular necrosis (AVN) is a rare progressive degenerative disease leading to bone and joint destruction. Patients often require surgical intervention. Femoral AVN is the most common anatomical location. Hyperbaric oxygen treatment (HBOT) has been shown to be effective in AVN. We present data collected from one centre over a 30-year period and compare the results with other published data. Methods: A retrospective chart review of all patients receiving HBOT for AVN at Fremantle and Fiona Stanley Hospitals since 1989 was performed. The primary outcome was radiological appearance using the Steinberg score, with secondary outcomes being subjective improvement, the need for joint replacement surgery and rates of complications. Results: Twenty-one joints in 14 patients (14 femoral heads and seven femoral condyles) were treated with HBOT since 1989. Two patients were excluded. Within the femoral head group, nine of the 14 joints (64%) had stable or improved magnetic resonance imaging (MRI) scans post treatment and at six months (minimum); 10 joints (71%) had good outcomes subjectively, three joints required surgical intervention, and three patients developed mild aural barotrauma. Within the femoral condyle group, all five joints had stable or improved post-treatment MRI scans (four had visible improvement in oedema and/or chondral stability), four joints reported good outcomes subjectively, none of the patients required surgical intervention (follow-up > six months). Conclusions: This single centre retrospective study observed prevention of disease progression in femoral AVN with the use of HBOT, comparable to other published studies. This adds to the body of evidence that HBOT may have a significant role in the treatment of femoral AVN.

Hierarchical Chiral Calcium Silicate Hydrate Films Promote Vascularization for Tendon-to-Bone Healing.

Revascularization after rotator cuff repair is crucial for tendon-to-bone healing. The chirality of materials has been reported to influence their performance in tissue repair. However, data on the use of chiral structures to optimize biomaterials as a revascularization strategy remain scarce. Here, calcium silicate hydrate (CSO) films with hierarchical chirality on the atomic to micrometer scale are developed. Interestingly, levorotatory CSO (L-CSO) films promote the migration and angiogenesis of endothelial cells, whereas dextral and racemic CSO films do not induce the same effects. Molecular analysis demonstrates that L-chirality can be recognized by integrin receptors and leads to the formation of focal adhesion, which activates mechanosensitive ion channel transient receptor potential vanilloid 4 to conduct Ca2+ influx. Consequently, the phosphorylation of serum response factor is biased by Ca2+ influx to promote the vascular endothelial growth factor receptor 2 signaling pathway, resulting in enhanced angiogenesis. After implanted in a rat rotator cuff tear model, L-CSO films strongly enhance vascularization at the enthesis, promoting collagen maturation, increasing bone and fibrocartilage formation, and eventually improving the biomechanical strength. This study reveals the mechanism through which chirality influences angiogenesis in endothelial cells and provides a critical theoretical foundation for the clinical application of chiral biomaterials.

Murine iPSC-Loaded Scaffold Grafts Improve Bone Regeneration in Critical-Size Bone Defects.

In certain situations, bones do not heal completely after fracturing. One of these situations is a critical-size bone defect where the bone cannot heal spontaneously. In such a case, complex fracture treatment over a long period of time is required, which carries a relevant risk of complications. The common methods used, such as autologous and allogeneic grafts, do not always lead to successful treatment results. Current approaches to increasing bone formation to bridge the gap include the application of stem cells on the fracture side. While most studies investigated the use of mesenchymal stromal cells, less evidence exists about induced pluripotent stem cells (iPSC). In this study, we investigated the potential of mouse iPSC-loaded scaffolds and decellularized scaffolds containing extracellular matrix from iPSCs for treating critical-size bone defects in a mouse model. In vitro differentiation followed by Alizarin Red staining and quantitative reverse transcription polymerase chain reaction confirmed the osteogenic differentiation potential of the iPSCs lines. Subsequently, an in vivo trial using a mouse model (n = 12) for critical-size bone defect was conducted, in which a PLGA/aCaP osteoconductive scaffold was transplanted into the bone defect for 9 weeks. Three groups (each n = 4) were defined as (1) osteoconductive scaffold only (control), (2) iPSC-derived extracellular matrix seeded on a scaffold and (3) iPSC seeded on a scaffold. Micro-CT and histological analysis show that iPSCs grafted onto an osteoconductive scaffold followed by induction of osteogenic differentiation resulted in significantly higher bone volume 9 weeks after implantation than an osteoconductive scaffold alone. Transplantation of iPSC-seeded PLGA/aCaP scaffolds may improve bone regeneration in critical-size bone defects in mice.

Transforming the Management of Articular Fractures in the Foot: A Critical Examination of Current Methods and Future Directions: A Review.

This study provides a comprehensive examination of the current methodologies and potential strategies for the treatment of articular fractures of the foot. In the field of orthopedic healthcare, these fractures present a significant challenge due to their complex nature and the fact that they affect the routines of patients. The motivation behind this study is based on two main concepts. The first one is represented by the use of emerging medical technologies and personalized medicine to bring a significant transformation in the management of foot fractures and give a better quality of treatment that is accepted by the patient. However, because there are inequities in the availability of the necessary medical care and equipment, as well as uneven incorporation in clinical settings, new technologies cannot be used to treat these types of fractures. Regarding the second concept behind this study, it is indicated that although current treatment methods are essential, they have a number of shortcomings when it comes to properly addressing these types of injuries. An approach is needed that takes into account the biomechanical points of view and the particularities of each patient. This approach could be applied in all hospital settings. Through this study, we want to highlight the progress made in recent years in surgical techniques such as 3D printing, minimally invasive surgery (MIS), and biological products. However, in the application of this new discovery, new obstacles have been discovered that prevent the efficient treatment of these types of injuries. This study examines the effectiveness and limitations of current treatments, as well as how differences in healthcare, such as available equipment, training of medical staff, and technological advances, affect patient outcomes in everyday life. This research wishes to emphasize that continuous innovation, interdisciplinary collaboration, and the use of an optimal approach that is appropriate for each patient, are essential. This study aims to provide new insights and useful recommendations for future research and clinical practice. The main role of this research is to improve the quality of life of patients and increase the standards of care in this complex field, which is in permanent evolution.

Evaluation of recombinant human erythropoietin as a promoter of bone healing in cats with femoral fractures.

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.

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At present, implant restoration has become a hot research topic in the field of prosthodontics. The in-depth studies of new materials and new technologies enable immediate implantation, immediate and early loading to be realized, which meets the needs of patients for shortening the course of implant restoration and obtaining better aesthetic effects. However, compared with the traditional delayed implantation technology, it is equally challenging for clinicians how to achieve and even improve the initial and long-term stability of implants in order to raise the success rate of implant restoration. The initial stability of the implant is influenced by a combination of factors, including the implant, the patient's condition, and the surgical procedure. Recently, there have been a lot of studies on the influencing factors and common research methods for immediate implant stability and bone healing. Summarizing and analyzing them can provide reference for preoperative evaluation, surgical plan and loading timing of immediate implant restoration in the later stage.

Efficacy of mesenchymal stem cell-based therapy on the bone repair of hypertensive rats.

OBJECTIVE: Hypertension disrupts the bone integrity and its repair ability. This study explores the efficiency of a therapy based on the application of mesenchymal stem cells (MSCs) to repair bone defects of spontaneously hypertensive rats (SHR). METHODS: First, we evaluated SHR in terms of bone morphometry and differentiation of MSCs into osteoblasts. Then, the effects of the interactions between MSCs from normotensive rats (NTR-MSCs) cocultured with SHR (SHR-MSCs) on the osteoblast differentiation of both cell populations were evaluated. Also, bone formation into calvarial defects of SHR treated with NTR-MSCs was analyzed. RESULTS: Hypertension induced bone loss evidenced by reduced bone morphometric parameters of femurs of SHR compared with NTR as well as decreased osteoblast differentiation of SHR-MSCs compared with NTR-MSCs. NTR-MSCs partially restored the capacity of SHR-MSCs to differentiate into osteoblasts, while SHR-MSCs exhibited a slight negative effect on NTR-MSCs. An enhanced bone repair was observed in defects treated with NTR-MSCs compared with control, stressing this cell therapy efficacy even in bones damaged by hypertension. CONCLUSION: The use of MSCs derived from a heathy environment can be in the near future a smart approach to treat bone loss in the context of regenerative dentistry for oral rehabilitation of hypertensive patients.

An adaptive biodegradable zinc alloy with bidirectional regulation of bone homeostasis for treating fractures and aged bone defects.

Healing of fractures or bone defects is significantly hindered by overactivated osteoclasts and inhibited osteogenesis in patients with abnormal bone metabolism. Current clinical approaches using titanium alloys or stainless steel provide mechanical support but have no biological effects on bone regeneration. Therefore, designing and fabricating degradable metal materials with sufficient mechanical strength and bidirectional regulation of both osteoblasts and osteoclasts is a substantial challenge. Here, this study first reported an adaptive biodegradable Zn-0.8 Mg alloy with bidirectional regulation of bone homeostasis, which promotes osteogenic differentiation by activating the Pi3k/Akt pathway and inhibits osteoclast differentiation by inhibiting the GRB2/ERK pathway. The anti-osteolytic ability of the Zn-0.8 Mg alloy was verified in a mouse calvarial osteolysis model and its suitability for internal fracture fixation with high-strength screws was confirmed in the rabbit femoral condyle fracture model. Furthermore, in an aged postmenopausal rat femoral condyle defect model, 3D printed Zn-0.8 Mg scaffolds promoted excellent bone regeneration through adaptive structures with good mechanical properties and bidirectionally regulated bone metabolism, enabling personalized bone defect repair. These findings demonstrate the substantial potential of the Zn-0.8 Mg alloy for treating fractures or bone defects in patients with aberrant bone metabolism.