Search

AbstractThe most common type of proximal humerus fracture is surgical neck fracture. The purpose of this paper is to study the mechanical mechanism and the effect of bone degeneration on humeral surgical neck fractures. The right humerus finite element models were established based on CT computed tomography. The stress values and crack propagation process under an axial force were obtained. Three indexes (mechanical property, cortical bone thickness of diaphysis and cancellous bone volume fraction) in this article were used to describe bone degeneration. The results showed that the three models group with different index had the same conclusions. The calculation results showed that the higher the bone degeneration level, the shorter the fracture time and the lower the fracture stress. The crack initiated from the medial side of the humerus, then gradually grew toward lateral side along the both sides, and finally broke. The medial crack was flat and single like "a thin line", while the lateral fracture of the humerus was irregular and crushed into fragments. The medial humerus cracks were generated by tensile stress, while the lateral cracks were generated by compressive stress. The thickness of humerus diaphysis might be used as the index of fracture risk due to direct readability from clinical images and quantitative relation of fracture risk. This article would provide reference data for the treatment and prevention of humeral surgical neck fracture. [ABSTRACT FROM AUTHOR]

Objective: Postmenopausal changes in bone mass and structure compromise the mechanical properties of proximal humerus, predisposing it to low‐energy fractures with complex morphology. The aim of the study is to investigate associations of bone quality and estimated bone strength of the surgical neck with age after menopause. Methods: A total of 122 healthy postmenopausal women were recruited from December 2016 to December 2022 and assigned to three groups: the 50–59 years group, the 60–69 years group, and the older than 70 years group. Bone properties of the surgical neck, including volumetric bone mineral density (vBMD), cortical thickness (CTh), the periosteal and medullary size, and estimated indices of bone strength were evaluated by quantitative computed tomography. Results: Compared to the 50–59 years group, postmenopausal women aged over 70 years were characterized by lower cortical thickness (13.9%) and vBMD (6.65%), as well as reduced strength indices including the minimum and maximum section modulus (Zmin 18.11%, Zmax 21.71%), polar section modulus (Zpol 20.21%), and the minimum and maximum second moments of area (Imax 21.01%, Imin 21.43%). Meanwhile, the difference in periosteal diameter and perimeter, total area in three groups did not reach statistical significance. Both cortical thickness and vBMD value were inversely associated with age, showing 10.56% and 23.92% decline. Imax showed the greatest age‐related decrease between age of 54 and 86 years (39.08%), followed by Zmax (−35.77%), Imin (−35.73%), Zpol (−34.90%) and Imin (−23.92%).The strength indices had stronger correlations with cortical thickness than with bone size or density. Conclusion: In postmenopausal women, aging is associated with a significant decline in cortical bone thickness and mechanical strength of the proximal humerus, especially over the age of 70 years. [ABSTRACT FROM AUTHOR]

Surgical gesture recognition is an important research direction in the field of computer-assisted intervention. Currently, research on surgical gesture recognition primarily focuses on robotic surgery, with a lack of studies in traditional surgery, particularly open surgery. Therefore, this study established a dataset simulating open surgery for research on surgical gesture recognition in the field of open surgery. With the assistance of professional surgeons, we defined a vocabulary of 10 surgical gestures based on suturing tasks in open procedures. In addition, this paper proposes a surgical gesture recognition method that integrates the R3D network with a multi-head attention mechanism (R3D-MHA). This method uses the R3D network to extract spatiotemporal features and combines it with the multi-head attention mechanism for relational learning of these features. The effectiveness of the R3D-MHA method in the field of open surgery gesture recognition was validated through two experiments: offline recognition and online recognition. The accuracy at the gesture instance level for offline recognition was 92.3%, and the frame accuracy for online recognition was 73.4%. Finally, its performance was further validated on the publicly available JIGSAWS dataset. Compared to other online recognition methods, the accuracy improved without using additional data. This work lays the foundation for research on surgical gesture recognition in open surgery and has significant applications in process monitoring, surgeon skill assessment and educational training for open surgeries. [ABSTRACT FROM AUTHOR]

In order to understand the distribution of streaming potentials in cartilage pores, this paper established finite element model to analyze. The results showed that the streaming potential in cartilage micro-pores increased along the axis. The electric potential in 5 μm straight micro-pore was about 50 μV, and the electric potential of curved bifurcation model was about 30 μV. The pressure and Zeta potential had a linear growth relationship with the streaming potential. The streaming potential decreased with the increase of ion concentration until ion concentration was saturated. These results could provide a theoretical basis for cartilage research. [ABSTRACT FROM AUTHOR]

3D printed Titanium alloy is widely used as a material of artificial joints and its mechanical properties is a key factor for improving operation results. Because the elastic modulus of the 3 D printed titanium alloy specimen was related to the size of the metal blank. It is very difficult to identify mechanical parameters by traditional mechanics experiments. In this paper, according to the inverse analysis principle of the parameter estimation, a response surface methodology (RSM) was proposed to identify the mechanical parameters, based on finite element inverse analysis. The finite element models of femoral prosthesis stem were established in line with compression experiments. The material parameters were combined by central composite design (CCD), and the response surface (RS) models were constructed using a quadratic polynomial with cross terms and optimized using a genetic algorithm (GA). Finally, the best mechanical parameter combination of the femoral prosthesis was calculated. The calculated elastic modulus and Poisson's ratio of a 3 D printed titanium alloy femoral prosthesis stem were 109.07 GPa and 0.29, respectively, with the elastic modulus error being very small. The proposed method is effective and can be extended for the identification of mechanical parameters in other 3 D printed models. [ABSTRACT FROM AUTHOR]

Mechanical environment plays an important role in the growth of cells, tissues and organs, in the study of mechanobiology and tissue engineering, and loading bioreactor acts as the basic platform. We developed a combined multi-functional bioreactor based on linear motor, and studied on the loading performance of different modules and loading methods. In the rolling / sliding loading module, in the effective distance for 50mm case, the bioreactor frequency is 0.01Hz to 0.3Hz. Under tensile and compressive loading module, the minimum amplitude of the bioreactor can reached 0.01mm while the frequency can reach 10Hz. Under the impact test module, in the effective distance for 50mm case, acceleration a=54.16m/s2 can be realized. In the high acceleration cyclic loading module, acceleration 8Gcan be realized. The combined multi-functional bioreactor provides conditions for the study related mechanobiology and tissue engineering.

Triply periodic minimal surface (TPMS) is widely used because it can be used to control the shape of porous scaffolds precisely by formula. In this paper, an I-wrapped package (I-WP) type porous scaffolds were constructed. The finite element method was used to study the relationship between the wall thickness and period, the morphology and mechanical properties of the scaffolds, as well as to study the compression and fluid properties. It was found that the porosity of I-WP type scaffolds with different wall thicknesses (0.1 ~ 0.2 mm) and periods (I-WP 1 ~ I-WP 5) ranged from 68.01% ~ 96.48%, and the equivalent elastic modulus ranged from 0.655 ~ 18.602 GPa; the stress distribution of the scaffolds tended to be uniform with the increase of periods and wall thicknesses; the equivalent elastic modulus of the I-WP type scaffolds was basically unchanged after the topology optimization, and the permeability was improved by 52.3%. In conclusion, for the I-WP type scaffolds, the period parameter can be adjusted first, then the wall thickness parameter can be controlled. Topology optimization can be combined to meet the design requirements. The I-WP scaffolds constructed in this paper have good mechanical properties and meet the requirements of repairing human bone tissue, which may provide a new choice for the design of artificial bone trabecular scaffolds.

Cartilage surface fibrosis is an early sign of osteoarthritis and cartilage surface damage is closely related to load. The purpose of this study was to study the relationship between cartilage surface roughness and load. By applying impact, compression and fatigue loads on fresh porcine articular cartilage, the rough value of cartilage surface was measured at an interval of 10 min each time and the change rule of roughness before and after loading was obtained. It was found that the load increased the roughness of cartilage surface and the increased value was related to the load size. The time of roughness returning to the initial condition was related to the load type and the load size. The impact load had the greatest influence on the roughness of cartilage surface, followed by the severe fatigue load, compression load and mild fatigue load. This article provides reference data for revealing the pathogenesis of early osteoarthritis and preventing and treating articular cartilage diseases.