Acceleration of Bone Defect Healing and Regeneration by Low-Intensity Ultrasound Radiation Force in a Rat Tibial Model

Ultrasound-Driven Selenium Nanoparticles Realize Bone Defect Repair through Activating Selenoproteins to Regulate PI3K/AKT Signaling Pathway

Excessive and variable inflammation in bone defects is a key factor that impedes effective bone repair. Herein, an ultrasound-controlled composite hydrogel (LNT-SeNPs@Gel) integrating gelatin-methacryloyl and lentinan-decorated selenium nanoparticles (LNT-SeNPs) is developed, exhibiting strong antioxidant and anti-inflammatory properties to remodel the inflammatory microenvironment of bone defects. This hydrogel serves as a platform for integrating bifunctional ultrasound (ultrasound modulation, USc and ultrasound for repairing, USr), facilitating cascade treatment and reducing the overall treatment period. During the inflammatory phase of bone repair, USc remotely modulates the LNT-SeNPs@Gel hydrogel, regulating the release of LNT-SeNPs to inhibit the overproduction of reactive oxygen species (ROS) and inflammatory factors, ultimately remodeling the inflammatory microenvironment. Subsequently, USr could activate the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signaling pathway regulated by selenoproteins to enhance the osteogenesis of MC3T3-E1 cells, thereby accelerating the bone repair process. Consequently, the combination of bifunctional ultrasound and LNT-SeNPs@Gel significantly improves bone repair outcomes and reduces the treatment period in rats. In conclusion, this study implies that the coordinated integration of the dual effects of ultrasound is a promising strategy for handling the complex and lengthy bone defects repair.

Clinical investigation of extracorporeal shock wave therapy combined with kinesitherapy on the treatment of delayed union of tibia and fibula fractures

OBJECTIVE

To investigate the therapeutic efficacy of extracorporeal shock wave therapy (ESWT) combined with kinesitherapy (KT) for the treatment of delayed union of tibia and fibula fractures.

METHODS

A total of 68 patients with delayed healing of tibiofibular fractures were enrolled. These patients were divided into three groups: control, ESWT, and ESWT+KT. All patients underwent standard surgical treatment following the fracture. Patients in the ESWT group received shockwave therapy twice a week for 4 months, while those in the ESWT+KT group received additional exercise therapy twice a week over the same duration. The control group did not receive any specific intervention during this period. The pain levels of patients in all three groups were assessed using the Numerical Rating Scale (NRS) before and after treatment. Bone repair and callus formation were evaluated using the Lane-Sandhu and Fernandez-Esteve X-ray grading scales before and after treatment. Additionally, walking ability was assessed using the Functional Ambulation Classification (FAC), Hoffer walking ability grade, and Holden walking ability grade before and after treatment.

RESULTS

No significant differences were observed in patient baseline characteristics across the three groups (P > 0.05), indicating comparability among groups. Post-treatment, improvements were noted in the NRS, Lane-Sandhu X-ray scale, Fernandez-Esteve X-ray scale, FAC level, Hoffer grade, and Holden grade in all three groups compared to their respective pre-treatment values (P < 0.05). Notably, the Lane-Sandhu X-ray scale, FAC level, Hoffer grade, and Holden grade showed significant improvements in the ESWT+KT group after treatment compared to the control group (P < 0.05). Additionally, the ESWT group demonstrated significant improvements in FAC level and Holden grade compared to the control group after treatment (P < 0.05).

CONCLUSION

ESWT can enhance the walking function in patients with delayed union of tibia and fibula fractures. ESWT combined with KT demonstrates superior efficacy compared to monotherapy, as it not only improves walking function but also promotes bone healing.

Degradation behavior of porous magnesium alloy scaffold under the low-intensity pulsed ultrasound intervention and their effect on bone defects repair

Biodegradable porous magnesium alloy (pMg) scaffolds hold significant potential for repair of bone defects owing to favorable mechanical properties and biocompatibility. However, a critical challenge remains in matching the degradation rate of pMg scaffolds with the pace of bone regeneration. Low-intensity pulsed ultrasound (LIPUS) has emerged as a promising therapeutic strategy to enhance bone repair. In this study, femoral bone defects in Sprague-Dawley rats were implanted with pMg scaffolds, and LIPUS was applied to the defect sites post-operatively. This study primarily investigated the degradation behavior of pMg scaffolds in vivo experiments, as well as their reparative effects on bone defects under LIPUS intervention. In vivo analysis revealed that LIPUS intervention accelerated the degradation of pMg scaffolds by loosening the degradation layer, making it more susceptible to erosion. Concurrently, LIPUS enhanced the accumulation of beneficial calcium and phosphorus compounds on the surface of the pMg scaffolds. Furthermore, the pMg + LIPUS group exhibited enhanced bone formation and mineralization around the degradation site compared to the pMg group alone, attributed to the increasing osteocalcin (OCN) and type I collagen (COL-I) as well as reduction in osteolysis by pMg and LIPUS-induced osteogenesis effect. At the 24-week post-surgery, the hardness value (HV) of regeneration bone in the pMg + LIPUS group had a 15% increase compared to the pMg group and approached the HV of healthy bone. In conclusion, the promotion of bone tissue growth rate under the intervention of LIPUS in conjunction with the degradation rate of pMg scaffolds offers a novel clinical strategy for the repair of bone defects.

Devices for osteoarthritis symptoms treatment: a patent review

INTRODUCTION

Osteoarthritis is a musculoskeletal disease that can lead to the loss and inability of those affected to perform normal daily functions, which leads to a decrease in quality of life. The main symptoms of osteoarthritis are tenderness, joint pain, stiffness, crepitus, limited movement, and local inflammation.

AREAS COVERED

The selected patents were deposited from 2010 to April 2022 involving 57 documents that were in line with the study objective in the final selection. The patents were classified in years, country, and applicants. Also, the therapeutic fields that presented the most documents were electrical stimulation, phototherapy, and ultrasound, followed by magnetic, electromagnetic, and thermotherapy. Therefore, the most current therapies used in the documents are already on the market.

EXPERT OPINION

Although the OA is cureless, non-surgical treatments are classified as the primary management approach for this disease. The pharmacological and non-pharmacological therapies are employed to reduce its prevalence and ensure the effectiveness of treatments. A strategy for relieving OA symptoms is non-pharmacological treatment, which can be based on exercise and patient education, combined with other alternative therapies. These therapies are used as supplements to the main OA treatments, enhancing the effectiveness of treatment outcomes.

A longitudinal rat model for assessing postoperative recovery and bone healing following tibial osteotomy and plate fixation

BACKGROUND

Rodent models are commonly employed to validate preclinical disease models through the evaluation of postoperative behavior and allodynia. Our study investigates the dynamic interplay between pain and functional recovery in the context of traumatic osteotomy and surgical repair. Specifically, we established a rat model of tibial osteotomy, followed by internal fixation using a 5-hole Y-plate with 4 screws, to explore the hypothesis that histological bone healing is closely associated with functional recovery.

OBJECTIVE

Our primary objective was to assess the correlation between bone healing and functional outcomes in a rat model of tibial osteotomy and plate fixation.

METHODS

Seventeen male Sprague-Dawley rats underwent a metaphyseal transverse osteotomy of the proximal tibia, simulating a fracture-like injury. The resultant bone defect was meticulously repaired by realigning and stabilizing the bone surfaces with the Y-plate. To comprehensively assess recovery and healing, we performed quantitative and qualitative evaluations at 2, 4, 6, and 8 weeks post-surgery. Evaluation methods included micro-CT imaging, X-ray analysis, and histological examination to monitor bone defect healing. Concurrently, we employed video recording and gait analysis to evaluate functional recovery, encompassing parameters such as temporal symmetry, hindlimb duty factor imbalance, phase dispersion, and toe spread.

RESULTS

Our findings revealed complete healing of the bone defect at 8 weeks, as confirmed by micro-CT and histological assessments. Specifically, micro-CT data showed a decline in fracture volume over time, indicating progressive healing. Histological examination demonstrated the formation of new trabecular bone and the resolution of inflammation. Importantly, specific gait analysis parameters exhibited longitudinal changes consistent with bone healing. Hindlimb duty factor imbalance, hindlimb temporal symmetry, and phase dispersion correlated strongly with the healing process, emphasizing the direct link between bone healing and functional outcomes.

CONCLUSIONS

The establishment of this tibia osteotomy model underscores the association between bone healing and functional outcomes, emphasizing the feasibility of monitoring postoperative recovery using endpoint measurements. Our overarching objective is to employ this model for assessing the local efficacy of drug delivery devices in ameliorating post-surgical pain and enhancing functional recovery.

Influence of Low-Intensity Pulsed Ultrasound Parameters on the Bone Mineral Density in Rat Model: A Systematic Review

OBJECTIVE

Bone recovery typically depends on the age of organisms or the prevalence of metabolic disorders such as osteoporosis, which is a metabolic condition characterized by decreased bone strength and bone mineral density (BMD). Therefore, low-intensity pulsed ultrasound (LIPUS), a non-invasive method for osteogenic stimulation, presents promising results. However, heterogeneity in animal study designs is a typical characteristic. Hence, we conducted a systematic review to evaluate the effectiveness of LIPUS in the recovery of experimental bone defects using rat models. We examined the areal and volumetric BMD to identify LIPUS doses to be applied and evaluated the accuracy reported by previous studies.

METHODS

The Virtual Health Library regional portal, PubMed, Embase, EBSCOhost, Scopus and CAPES were reviewed for animal studies that compared fracture treatments based on LIPUS with sham or no treatments using rat models and reported BMD as an outcome. The tool provided by the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) and the Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies (CAMARADES) checklist were used to assess the bias and quality of such studies.

RESULTS

Of the six studies reviewed, the most frequently used LIPUS dose had an ultrasonic frequency of 1.0 MHz, repetition rate of 0.1 kHz and pulse duration of 2000 μs. An intensity (ISATA) of 30 mW/cm2 was the most preferred for bone recovery. However, the BMD could not solely irrefutably evaluate the effectiveness of LIPUS in bone recovery as the results were discordant with each other. The discrepancies in experimental methodologies, low-quality classifications and high risk of bias in the selected studies, however, did not validate the undertaking of a meta-analysis.

CONCLUSION

On the basis of the BMD results, no sufficient evidence was found to recommend the use of LIPUS for bone recovery in rat models. Thus, this systematic review indicates that the accuracy of such reports must be improved to improve their scientific quality to facilitate a transition of LIPUS applications from pre-clinical research to clinic use.

The effect of ultrasound on bone healing across a bone gap, an experimental study of a delayed union model

The aim of the study is to determine whether ultrasound accelerates bone repair across a bone gap. To replicate the clinical situation of bone repair in a severe tibial fracture, such as Gustilo grade three, we designed an experimental model to determine whether ultrasound can promote bone healing in the presence of a bone gap. The effect of ultrasound on bone healing of a tibial bone gap held in an external fixator was studied. 60 New Zealand White rabbits were divided into four groups. In one group of 6 animals, a tibial osteotomy was closed or compressed and studied at six weeks (Comparative Group). In 3 groups of 18 animals each, a tibial bone gap was maintained and was untreated, treated with ultrasound or mock ultrasound (Control Group). The repair of the bone gaps was studied in 3 animals each at 2,4,6,8,10 and 12 weeks. Investigation was by histology, angiography, radiography and densitometry. Three of the 18 untreated group progressed to delayed union, compared with 4 in the ultrasound and 3 in the mock ultrasound group (Control Group). Statistical analysis showed no difference between the three groups. 5 of the 6 closed/compressed osteotomies (Comparative Group) united faster at 6 weeks. The healing pattern of the bone gap groups were similar. We recommend this as a delayed union model. We found no evidence that ultrasound accelerated bone healing, reduced the rate of delayed union or increased callus formation in this model of delayed union. This study simulates delayed union following a compound tibial fracture and has clinical relevance concerning treatment of a delay in union with ultrasound.

Alkaline earth metals for osteogenic scaffolds: From mechanisms to applications

Regeneration of bone defects is a significant challenge today. As alternative approaches to the autologous bone, scaffold materials have remarkable features in treating bone defects; however, the various properties of current scaffold materials still fall short of expectations. Due to the osteogenic capability of alkaline earth metals, their application in scaffold materials has become an effective approach to improving their properties. Furthermore, numerous studies have shown that combining alkaline earth metals leads to better osteogenic properties than applying them alone. In this review, the physicochemical and physiological characteristics of alkaline earth metals are introduced, mainly focusing on their mechanisms and applications in osteogenesis, especially magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). Furthermore, this review highlights the possible cross-talk between pathways when alkaline earth metals are combined. Finally, some of the current drawbacks of scaffold materials are enumerated, such as the high corrosion rate of Mg scaffolds and defects in the mechanical properties of Ca scaffolds. Moreover, a brief perspective is also provided regarding future directions in this field. It is worth exploring that whether the levels of alkaline earth metals in newly regenerated bone differs from those in normal bone. The ideal ratio of each element in the bone tissue engineering scaffolds or the optimal concentration of each elemental ion in the created osteogenic environment still needs further exploration. The review not only summarizes the research developments in osteogenesis but also offers a direction for developing new scaffold materials.

The impact of low intensity ultrasound on cells: Underlying mechanisms and current status

Low intensity ultrasound (LIUS) has been adopted for a variety of therapeutic purposes because of its bioeffects such as thermal, mechanical, and cavitation effects. The mechanism of impact and cellular responses of LIUS in cellular regulations have been revealed, which helps to understand the role of LIUS in tumor treatment, stem cell therapy, and nervous system regulation. The review summarizes the bioeffects of LIUS at the cellular level and its related mechanisms, detailing the corresponding theoretical basis and latest research in the study of LIUS in the regulation of cells. In the future, the design of specific LIUS-mediated treatment strategies may benefit from promising investigations which is hoped to provide encouraging therapeutic data.

Low-Intensity Pulsed Ultrasound Stimulation for Bone Fractures Healing: A Review

Low-intensity pulsed ultrasound (LIPUS) is a developing technology, which has been proven to improve fracture healing process with minimal thermal effects. This noninvasive treatment accelerates bone formation through various molecular, biological, and biomechanical interactions with tissues and cells. Although LIPUS treatment has shown beneficial effects on different bone fracture locations, only very few studies have examined its effects on deeper bones. This study provides an overview on therapeutic ultrasound for fractured bones, possible mechanisms of action, clinical evidences, current limitations, and its future prospects.

Improved activity of MC3T3-E1 cells by the exciting piezoelectric BaTiO3/TC4 using low-intensity pulsed ultrasound

Developing bioactive materials for bone implants to enhance bone healing and bone growth has for years been the focus of clinical research. Barium titanate (BT) is an electroactive material that can generate electrical signals in response to applied mechanical forces. In this study, a BT piezoelectric ceramic coating was synthesized on the surface of a TC4 titanium alloy, forming a BT/TC4 material, and low-intensity pulsed ultrasound (LIPUS) was then applied as a mechanical stimulus. The combined effects on the biological responses of MC3T3-E1 cells were investigated. Results of scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction showed that an uniform nanospheres -shaped BT coating was formed on TC4 substrate. Piezoelectric behaviors were observed using piezoelectric force microscopy with the piezoelectric coefficient d33 of 0.42 pC/N. Electrochemical measures indicated that LIPUS-stimulated BT/TC4 materials could produce a microcurrent of approximately 10 μA/cm2. In vitro, the greatest osteogenesis (cell adhesion, proliferation, and osteogenic differentiation) was found in MC3T3-E1 cells when BT/TC4 was stimulated using LIPUS. Furthermore, the intracellular calcium ion concentration increased in these cells, possibly because opening of the L-type calcium ion channels was promoted and expression of the CaV1.2 protein was increased. Therefore, the piezoelectric BT/TC4 material with LIPUS loading synergistically promoted osteogenesis, rending it a potential treatment for early stage formation of reliable bone-implant contact.

Longitudinal effects of low-intensity pulsed ultrasound on osteoporosis and osteoporotic bone defect in ovariectomized rats

Low-intensity pulsed ultrasound (LIPUS) with an intensity (spatial average temporal average, I_SATA) of 30 mW/cm² has been widely proved to be effective on impaired bone healing, but showing little effectiveness in the treatment of osteoporosis. We hypothesized that the intensity of LIPUS may be a key factor in explaining this difference, thus two intensity levels, the widely used 30 mW/cm² and a higher 150 mW/cm², were used to simultaneously treat osteoporosis and osteoporotic bone defect in ovariectomized (OVX) rats with a 1-mm drill hole on their left femurs.Results showed that 150 mW/cm² LIPUS augmented the healing rate of the drill hole than 30 mW/cm² after 3-week LIPUS treatment, although did not further enhance the healing rate after 6-week LIPUS treatment. For ameliorating osteoporosis, 150 mW/cm² LIPUS achieved more advantages over 30 mW/cm² in improving bone density, microstructure and biomechanics 6 weeks after LIPUS intervention. In conclusion, LIPUS with an intensity of 30 mW/cm² was sufficient to facilitate bone defect healing, but a higher intensity can be considered as a rapid trigger for osteoporotic bone repair. In addition, improving the intensity of LIPUS may be a potentially effective consideration for alleviation of osteoporosis, and the LIPUS regimen in the treatment of osteoporosis remains to be optimized.

Astragaloside IV Improves Tibial Defect in Rats and Promotes Proliferation and Osteogenic Differentiation of hBMSCs through MiR-124-3p.1/STAT3 Axis

Astragaloside IV (AST-IV) facilitates the proliferation and migration of osteoblast-like cells. We sought to explore the effect and potential mechanism of AST-IV on regeneration of tibial defects. To reveal the effect of AST-IV on regeneration of tibial defects in rat, HE staining and microcomputed tomography (μCT) were performed on tibial bone. The binding relationship between miR-124-3p.1 and STAT3 was analyzed by TargetScan V7.2 and a dual-luciferase reporter assay. Human bone marrow mesenchymal stromal/stem cells (hBMSCs) were identified by morphological observation and flow-cytometric analysis. To reveal the effect and mechanism of AST-IV on phenotypes of hBMSCs, hBMSCs were treated with AST-IV, miR-124-3p.1 mimic, and pcDNA-STAT3, and cell viability, cell cycle, ALP activity, and calcium deposition of hBMSCs in vitro were determined by MTT, flow-cytometric analysis, ELISA, and Alizarin red staining, respectively. The expressions of osteoblast marker molecules (RUNX2, OCN, Smad4), miR-124-3p.1, and STAT3 were indicated by RT-qPCR and Western blot. AST-IV decreased miR-124-3p.1 expression, increased STAT3 expression in tibial bone defects, and promoted regeneration of tibial bone defects in a concentration-dependent manner. The hBMSCs appeared spindle-shaped and were positive for CD105, but negative for CD34. MiR-124-3p.1 negatively regulated STAT3 expression in hBMSCs under osteogenic conditions. AST-IV promoted viability, cell cycle, ALP activity, and osteogenic differentiation of hBMSCs along with increased expressions of osteoblast marker molecules, which was partially reversed by miR-124-3p.1 overexpression. However, the effect of miR-124-3p.1 overexpression on hBMSCs was also partially reversed by STAT3 overexpression. AST-IV improves tibial defects in rats and promotes proliferation and osteogenic differentiation of hBMSCs through the miR-124-3p.1/STAT3 axis.

Effects of collimated and focused low-intensity pulsed ultrasound stimulation on the mandible repair in rabbits

Background

This study was to evaluate the effects of low-intensity collimated pulse ultrasound (LICU) and low-intensity focused-pulse ultrasound (LIFU) stimulation on the osteogenesis in the porous silicon carbide (SiC) scaffold implanted in the rabbit mandible.

Methods

Rabbits were randomly divided into LIFU group, LICU group and control group (without ultrasound treatment). The intensities of LICU and LIFU were 30 and 300 mW/cm², respectively. The subcutaneous and subperiosteal temperatures were measured continuously during the 20-min ultrasound treatment. Then, the porous SiC scaffolds were implanted into the mandible, followed by LICU or LIFU once daily, and the quantity and structure of bone were assessed by methylene blue-acid fuchsin staining and micro-CT at 3, 6 and 9 weeks after implantation.

Results

The changes in the subcutaneous and subperiosteal temperatures during LICU and LIFU were less than 1 °C. The bone mass increased and the structure of bone tissues became more mature over time. The bone mass and mean pore occupancy fraction (POF) in the LIFU group were significantly greater than in the LICU group at three time points (P<0.05). Bone ingrowth in different directions was observed, and the new bone formation in the mesial, distal, top, and lingual sides of the implants in the LIFU group was greater than in the LICU group and control group (P<0.05).

Conclusions

LIFU and LICU may effectively promote bone formation in the mandible scaffold, and LIFU significantly accelerates bone formation in both buccal side and lingual side of the scaffold.

Histomorphometric Evaluation of Critical-Sized Bone Defects Using Osteomeasure and Aperio Image Analysis Systems

Most histological evaluations of critical-sized bone defects are limited to the analysis of a few regions of interest at a time. Manual and semiautomated histomorphometric approaches often have intra- and interobserver subjectivity, as well as variability in image analysis methods. Moreover, the production of large image data sets makes histological assessment and histomorphometric analysis labor intensive and time consuming. Herein, we tested and compared two image segmentation methods: thresholding (automated) and region-based (manual) modes, for quantifying complete image sets across entire critical-sized bone defects, using the widely used Osteomeasure system and the freely downloadable Aperio Image Scope software. A comparison of bone histomorphometric data showed strong agreement between the automated segmentation mode of the Osteomeasure software with the manual segmentation mode of Aperio Image Scope analysis (bone formation R² = 0.9615 and fibrous tissue formation R² = 0.8734). These results indicate that Aperio is capable of handling large histological images, with excellent speed performance in producing highly consistent histomorphometric evaluations compared with the Osteomeasure image analysis system. The statistical evaluation of these two major bone parameters demonstrated that Aperio Image Scope is as capable as Osteomeasure. This study developed a protocol to improve the quality of results and reduce analysis time, while also promoting the standardization of image analysis protocols for the histomorphometric analysis of critical-sized bone defect samples. Impact Statement Despite bone tissue engineering innovations increasing over the last decade, histomorphometric analysis of large bone defects used to study such approaches continues to pose a challenge for pathological assessment. This is due to the resulting large image data set, and the lack of a gold standard image analysis protocol to quantify histological outcomes. Herein, we present a standardized protocol for the image analysis of critical-sized bone defect samples stained with Goldner's Trichrome using the Osteomeasure and Aperio Image Scope image analysis systems. The results were critically examined to determine their reproducibility and accuracy for analyzing large bone defects.

Periodontal tissue regeneration after low-intensity pulsed ultrasound stimulation with or without intra-marrow perforation in two-wall intra-bony defects-A pilot study in dogs

AIM

To evaluate the effects of low-intensity pulsed ultrasound (LIPUS) with/without intra-marrow perforation (IMP) on periodontal healing in two-wall intra-bony defects in dogs.

MATERIALS AND METHODS

Two-wall intra-bony defects (5 mm wide, 5 mm deep) were created at the distal and mesial aspects of mandibular premolars in four beagle dogs (four defects per dog). The 16 defects were divided into four treatment groups: IMP, LIPUS, IMP + LIPUS (IMP/LIPUS) and control (open flap debridement). The LIPUS and IMP/LIPUS sites received daily LIPUS exposure for 3 weeks starting 1 week after surgery. The animals were euthanized 4 weeks after surgery for histologic evaluation.

RESULTS

There was significantly greater new bone formation at LIPUS (2.93 ± 0.74 mm) and IMP/LIPUS (3.18 ± 0.52 mm) sites than at control sites (1.65 ± 0.46 mm). New bone area at LIPUS (6.36 ± 2.28 mm² ) and IMP/LIPUS (6.13 ± 1.25 mm² ) sites was significantly greater than that at control sites (2.15 ± 1.75 mm² ). New cementum length at LIPUS sites (4.09 ± 0.75 mm) was significantly greater than that at control (2.29 ± 1.02 mm) and IMP (2.41 ± 0.41 mm) sites. No significant difference was observed between LIPUS and IMP/LIPUS sites in any histomorphometric parameter.

CONCLUSIONS

These findings suggest that LIPUS effectively promotes periodontal regeneration in two-wall intra-bony defects in dogs.