BACKGROUND: The infrazygomatic crest mini-screw has been widely used, but the biomechanical performance of mini-screws at different insertion angles is still uncertain. The aim of this study was to analyse the primary stability of infrazygomatic crest mini-screws at different angles and to explore the effects of the exposure length (EL), screw-cortical bone contact area (SCA), and screw-trabecular bone contact area (STA) on this primary stability.
METHODS: Ninety synthetic bones were assigned to nine groups to insert mini-screws at the cross-combined angles in the occlusogingival and mesiodistal directions. SCA, STA, EL, and lateral pull-out strength (LPS) were measured, and their relationships were analysed. Twelve mini-screws were then inserted at the optimal and poor angulations into the maxillae from six fresh cadaver heads, and the same biomechanical metrics were measured for validation.
RESULTS: In the synthetic-bone test, the LPS, SCA, STA, and EL had significant correlations with the angle in the occlusogingival direction (rLPS = 0.886, rSCA = -0.946, rSTA = 0.911, and rEL= -0.731; all P < 0.001). In the cadaver-validation test, significant differences were noted in the LPS (P = 0.011), SCA (P = 0.020), STA (P = 0.004), and EL (P = 0.001) between the poor and optimal angulations in the occlusogingival direction. The STA had positive correlations with LPS (rs = 0.245 [synthetic-bone test] and r = 0.720 [cadaver-validation test]; both P < 0.05).
CONCLUSIONS: The primary stability of the infrazygomatic crest mini-screw was correlated with occlusogingival angulations. The STA significantly affected the primary stability of the infrazygomatic crest mini-screw, but the SCA and EL did not.

Aim: To assess the efficacy of a bioregenerative scaffold derived from bone marrow aspirate, cancellous bone autograft, platelet-rich plasma and autologous fibrin in treating supracondylar femur nonunions. Methods & materials: Three patients with nonunions following multiple surgical failures underwent bone stabilization and the application of a novel bioregenerative scaffold. x-rays and subjective scales were collected before surgery and at 6, 12 and 24 months post-surgery. Results: All nonunions exhibited healing with sufficient callus formation, as confirmed radiologically. After 6 months, all patients resumed full weight-bearing walking without pain. Statistical analysis showed improvements in all scales compared with pre-surgical values. Conclusion: This method presents itself as an option for treating supracondylar femur nonunions following multiple surgical failures.
What is this summary about? The objective of this case series study was to evaluate the effectiveness of a new biological autologous scaffold, comprised of stem and blood cells along with blood derivatives, in treating challenging cases of supracondylar femur nonunions.What were the results? Three participants underwent the application of this surgical method and were monitored for a period of 2 years. The therapy was well tolerated and deemed safe. Notably, all three patients experienced significant reductions in pain and improvements in functionality. Within a few months, they were able to walk with full weightbearing without pain, and clear indications of progressing toward bone union were evident by the 6 months.What do the results mean? This study demonstrates that the surgical application of autologous blood, cancellous bone and bone marrow, following the described concept and method, is an effective, safe and enduring treatment for femur nonunions. It markedly diminishes pain, enhances leg function and yields statistically significant improvements in quality of life.

OBJECTIVE: This study aimed to investigate the association between weight-adjusted waist index (WWI) and trabecular bone score (TBS) and to assess the ability of WWI to identify individuals with degraded bone microarchitecture (DBMA).
METHODS: This cross-sectional study included participants aged 20 and older from the National Health and Nutrition Examination Survey. Furthermore, WWI was calculated by waist circumference and body weight. In addition, linear regression models were employed to investigate the association between WWI and TBS, while logistic regression models were employed to determine the association between WWI and the risk of DBMA. Finally, the performance of WWI in identifying individuals with DBMA was using the receiver operating characteristic (ROC) curves with area under the ROC curve.
RESULTS: A total of 4,179 participants with a mean age of 49.90 years were included in the final analysis. WWI was negatively associated with TBS and positively associated with an increased risk of DBMA. Furthermore, the associations between WWI and TBS, as well as DBMA risk, were stable regardless of stratification by age, sex, race, or body mass index (BMI). Moreover, WWI achieved good performances in identifying individuals with DBMA or low TBS. In addition, the combination of WWI and BMI showed better performances in identifying individuals with DBMA or low TBS than WWI or BMI alone.
CONCLUSIONS: WWI established a negative association with TBS and a positive association with the risk of DBMA. Clinicians should be alert to the potential risk of DBMA among individuals with high WWI. Moreover, WWI, alone or in combination with BMI, has the potential to serve as an early screening strategy in identifying individuals with DBMA.

OBJECTIVE: To perform a quantitative analysis of the amount of cancellous bone in the distal radius and olecranon process by segmentation of computed tomographic scans. As a secondary analysis, the bone density by Hounsfield units was evaluated at the same sites.
METHODS: Computed tomography angiography images of the upper extremity were analyzed using 3-D Slicer™ medical imaging software. Bone volume (cm3) and density (Hounsfield units) from the cancellous bone between the distal radius and the olecranon process were compared by creating an advanced three-dimensional model. The images were analyzed in duplicate, and an intraclass correlation was performed to assess measurement consistency.
RESULTS: Twenty subjects were included. A total volume of 5.01 ± 1.21 cm3 and 5.81 ± 1.61 cm3 for the distal radius and the olecranon process (p < .0001), respectively, was found. Regarding Hounsfield units, the density of the olecranon process was 303.1 ± 73.26, and the distal radius was 206.5 ± 63.73 (p < .0001). All intraclass correlation coefficients were >0.992.
CONCLUSIONS: These results suggest that the olecranon process has a greater volume and a higher bone mineral density than the distal radius. With these results, the surgeon will have the ability to decide the quantity and quality of bone grafts according to the surgical procedure.

This study aims to investigate tissue differentiation during mandibular reconstruction with particulate cancellous bone marrow (PCBM) graft healing using biphasic mechanoregulation theory under four bite force magnitudes and four implant elastic moduli to examine its implications on healing rate, implant stress distribution, new bone elastic modulus, mandible equivalent stiffness, and load-sharing progression. The finite element model of a half Canis lupus mandible, symmetrical about the midsagittal plane, with two marginal defects filled by PCBM graft and stabilized by porous implants, was simulated for 12 weeks. Eight different scenarios, which consist of four bite force magnitudes and four implant elastic moduli, were tested. It was found that the tissue differentiation pattern corroborates the experimental findings, where the new bone propagates from the superior side and the buccal and lingual sides in contact with the native bone, starting from the outer regions and progressing inward. Faster healing and quicker development of bone graft elastic modulus and mandible equivalent stiffness were observed in the variants with lower bite force magnitude and or larger implant elastic modulus. A load-sharing condition was found as the healing progressed, with M3 (Ti6Al4V) being better than M4 (stainless steel), indicating the higher stress shielding potentials of M4 in the long term. This study has implications for a better understanding of mandibular reconstruction mechanobiology and demonstrated a novel in silico framework that can be used for post-operative planning, failure prevention, and implant design in a better way.

OBJECTIVE: The study employed three-dimensional (3D) finite element analysis (FEA) and examined how implant diameters affect stress distribution across the implant-bone contact and how stress transmission through this interface changes during axial and non-axial loading.
METHODS: A 3D mandibular model was created using cone beam CT of a patient with implants inserted into the first mandible molar. Nobel Biocare implants (Nobel Biocare, Switzerland) with specific dimensions of 3.5 mm, 4.3 mm, 5.0 mm, and 6.0 mm were chosen. Models were created in CATIAV5R19 (Dassault Systemes, France) from threaded titanium implant dimensions. Implants were finite element-modeled utilizing ANSYS Workbench v11.0 (Ansys, Inc, Pennsylvania, USA). The analysis involved applying 100 N axial, 50 N buccolingual, and 50 N mesiodistal loads.
RESULTS: In a lower first molar bone segment, the implant top surface was loaded in 100 N axial, 50 N buccolingual, and 50 N mesiodistal orientations. The cortical bone proximal to the implant neck had the most von Mises stress, regardless of model or stress scenario. In Model I cortical bone, maximal stress was centered at the implant neck. Most stress was on lingual bone plates, lesser on buccal, and least on mesial and distal. Less than half of the implant stress was transmitted to the cortical bone. The stress transferred from the implant to the cortical bone in Model II was less than half of the implant stress. The same was true for Models III and IV. In Model I cancellous bone, stress was concentrated in the implant\'s coronal half and minimal in the apical half.
CONCLUSIONS: The stress patterns under axial loading were distributed favorably. Therefore, it can be inferred that an augmentation in the diameter of the implant enhances the even distribution of stress at the interface between the bone and the implant by offering a larger surface area for the dispersion of stress. Furthermore, it was determined that applying force along an implant\'s axis was a beneficial loading direction and did not negatively impact its lifespan.

UNASSIGNED: The accuracy of pedicle screw fixation is crucial for patient safety. Traditional navigation methods based on computed tomography (CT) imaging have several limitations. Therefore, this study aimed to investigate the ultrasonic propagation characteristics of bone tissue and their relationship with CT imaging results, as well as the potential application of ultrasound navigation in pedicle screw fixation.
UNASSIGNED: The study used three bovine spine specimens (BSSs) and five human vertebral allograft bones (HABs) to progressively decrease the thickness of the cancellous bone layer, simulating the process of pedicle screw perforation. Five unfocused miniature ultrasound probes with frequencies of 2.2, 2.5, 3, 12, and 30 MHz were employed for investigating the ultrasonic propagation characteristics of cancellous and cortical bone through ultrasound transmission and backscatter experiments. The CT features of the bone tissue was obtained with the Skyscan 1174 micro-CT scanner (Bruker, Billerica, MA, USA).
UNASSIGNED: The experimental results demonstrated that low-frequency (2-3 MHz) ultrasound effectively penetrated the cancellous bone layer up to a depth of approximately 5 mm, with an attenuation coefficient below 10 dB/cm. Conversely, high-frequency (12 MHz) ultrasound exhibited significant signal attenuation in cancellous bone, reaching up to 55.8 dB/cm. The amplitude of the backscattered signal at the cancellous bone interface exhibited a negative correlation with the bone sample thickness (average r=-0.84), meaning that as the thickness of the cancellous bone layer on the cortical bone decreases, the backscattered signal amplitude gradually increases (P<0.05). Upon reaching the cortical bone interface, there was a rapid surge in echo signal amplitude, up to 8 times higher. Meanwhile, the statistical results indicated a significant correlation between the amplitude of the echo signal and the micro-CT scanning results of bone trabecular structure.
UNASSIGNED: Theoretically, using multiple ultrasonic probes (≥3) and regions of interest (ROIs) (≥5) has the potential to provide surgeons with early warning signals for pedicle perforation based on three or more successive increases in echo signal amplitude or a sudden substantial increase. The statistical results indicate a significant correlation between the amplitude of the echo signal and the micro-CT scanning results of bone trabeculae, suggesting the potential use of ultrasound as opposed to CT for real-time intraoperative bone navigation.

Type 2 Diabetes (T2D) is associated with fractures, despite preserved Bone Mineral Density (BMD). This study aimed to evaluate the relationship between BMD and trabecular bone score (TBS) with the reallocation of fat within muscle in individuals with eutrophy, obesity, and T2D.
The subjects were divided into three groups: eutrophic controls paired by age and sex with the T2D group (n = 23), controls diagnosed with obesity paired by age, sex, and body mass index with the T2D group (n = 27), and the T2D group (n = 29). BMD and body fat percentage were determined using dual-energy X-Ray absorptiometry. TBS was determined using TBS iNsight software. Intra and extramyocellular lipids in the soleus were measured using proton magnetic resonance spectroscopy.
TBS was lower in the T2D group than in the other two groups. Glycated hemoglobin (A1c) was negatively associated with TBS. Body fat percentage was negatively associated with TBS and Total Hip (TH) BMD. TH BMD was positively associated with intramuscular lipids. A trend of negative association was observed between intramuscular lipids and TBS.
This study showed for the first time that the reallocation of lipids within muscle has a negative association with TBS. Moreover, these results are consistent with previous studies showing a negative association between a parameter related to insulin resistance (intramuscular lipids) and TBS.

Miniscrews are widely used in orthodontics as an anchorage device while aligning teeth. Shear stress in the miniscrew-bone interface is an important factor when the miniscrew makes contact with the bone. The objective of this study was to analyze the shear stress and force in the screw-bone interface for varying Cortical Bone Thickness (CBT) using Finite Element Analysis (FEA). Varying CBT of 1.09 mm (1.09CBT) and 2.66 mm (2.66CBT) with miniscrews of Ø1.2 mm, 10 mm length (T1), Ø1.2 mm, 6 mm length (T2) and Ø1.6 mm, 8 mm length (T3) were analyzed. Six Finite Element (FE) models were developed with cortical, cancellous bone, miniscrews and gingiva as a prism. A deflection of 0.1 mm was applied on the neck of the miniscrews at 0°, +30° and -30° angles. The shear stress and force in the screw-bone interface were assessed. The results showed that the CBT affects the shear stress and force in the screw-bone interface region in addition to the screw dimensions and deflection angulations. T1 screw generated lesser shear stress in 1.09CBTand 2.66CBTcompared to T2 and T3 screws. Higher CBT is preferred for better primary stability in shear aspect. Clinically applied forces of 200 gms to 300 gms to an anchorage device induces shear stress in the miniscrew-bone interface region might cause stress shielding. Thus, clinicians need to consider the effect of varying CBT and the size of the miniscrews for the stability, reduced stress shielding and better anchorage during orthodontic treatment.

Micro-Finite Element analysis (μFEA) has become widely used in biomechanical research as a reliable tool for the prediction of bone mechanical properties within its microstructure such as apparent elastic modulus and strength. However, this method requires substantial computational resources and processing time. Here, we propose a computationally efficient alternative to FEA that can provide an accurate estimation of bone trabecular mechanical properties in a fast and quantitative way. A lattice element method (LEM) framework based on the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) open-source software package is employed to calculate the elastic response of trabecular bone cores. A novel procedure to handle pore-material boundaries is presented, referred to as the Firm and Floppy Boundary LEM (FFB-LEM). Our FFB-LEM calculations are compared to voxel- and geometry-based FEA benchmarks incorporating bovine and human trabecular bone cores imaged by micro Computed Tomography (μCT). Using 14 computer cores, the apparent elastic modulus calculation of a trabecular bone core from a μCT-based input with FFB-LEM required about 15 min, including conversion of the μCT data into a LAMMPS input file. In contrast, the FEA calculations on the same system including the mesh generation, required approximately 30 and 50 min for voxel- and geometry-based FEA, respectively. There were no statistically significant differences between FFB-LEM and voxel- or geometry-based FEA apparent elastic moduli (+24.3% or +7.41%, and +0.630% or -5.29% differences for bovine and human samples, respectively).