To investigate the effects of patient bone mass differences on the stability of unicondylar knee arthroplasty (UKA) prostheses.

A UKA finite element model was established to quantify the effects of five different bone quality conditions on the proximal tibial von Mises stress, bone-prosthesis fixation interface contact stress, and bone-prosthesis fixation interface micromotion, using the medial knee force and joint motion predicted by the individualized UKA musculoskeletal multibody dynamics model as boundary conditions.

The influences of bone strength on the proximal tibia von Mises stress and bone-prosthesis fixation interface contact stress were not obvious, and the difference in peak values of the proximal tibia von Mises stress between two groups of models with the largest difference in bone strength was not more than 5%, and the difference in peak values of the bone-prosthesis fixation interface contact stress was only 2.37 MPa. However, the influence of bone strength on the bone-prosthesis fixation interface micromotion was significant, and the weaker bones were more prone to cause the bone-prosthesis fixation interface micromotion. However, bone strength had a significant effect on the bone-prosthesis fixation interface micromotion, and weak bone was more likely to cause changes in the bone-prosthesis fixation interface micromotion. Compared to patients with the neutral bone quality, the prosthesis fixation interface micromotion increased by 84.67% at 20% gait cycles for patients with the weakest bone quality.

UKA patients with a weaker bone quality have a higher risk of prosthesis loosening. It is recommended that surgeons should carefully choose their surgical strategy in order to reduce the rate of postoperative revision in UKA.

To investigate the effect of postoperative reduction quality in femoral neck fracture internal fixation on mechanical properties of the femoral head from the perspective of trabecular bone biomechanics.

From patients who underwent hip replacement surgery for femoral neck fractures, a total of 26 femoral head slice specimens were obtained. The central axis of the primary compressive trabeculae was defined as the 0° group, with the intersection point of the primary compressive trabeculae and the femoral calcar serving as the center. By rotating the specimens to simulate different reduction angles, the cut femoral head slice specimens were randomly divided into five groups: -10°, -5°, 0°, 5°, and 10°, representing femoral heads with varying reduction qualities. The specimens were subjected to single compression load tests and fatigue load tests. The load was set from 70 N to 1 400 N, at a frequency of 1 Hz, with 10 000 cycles. Axial stiffness, displacement, and the number of collapse cycles were measured, to compare the biomechanical properties of femoral head specimens under different reduction qualities.

There were differences in the axial stiffness, displacement, and number of collapse cycles among the femoral head specimens in different groups. Under 800 N load, the axial stiffness of 0° group was significantly greater than that of ±10° groups (P<0.05). The axial stiffness of 0° group was also greater than that of the ±5° groups, but the differences were not statistically significant (P>0.05). The axial stiffness of ±5° groups was greater than that of ±10° groups (P<0.05). 0° group had a lower displacement than ±5° groups and ±10° groups. However, the differences in displacement between 0° group and ±5° groups were not statistically significant (P>0.05), while the differences between the 0° group and ±10° groups were statistically significant (P<0.05). The differences in displacement between ±5° groups and ±10° groups were also statistically significant (P<0.05). 0° group had a significantly higher number of collapse cycles than ±10° groups (P<0.05). The number of collapse cycles in 0° group was also higher than that in ±5° groups, but the differences were not statistically significant (P>0.05). The number of collapse cycles in ±5° groups was significantly higher than that ±10° groups (P<0.05).

The quality of reduction after internal fixation of femoral neck fractures significantly affects the biomechanical properties of the femoral head. This study provides a scientific basis for optimizing treatment and postoperative management, aiming to improve clinical outcomes and patients’ quality of life.

To achieve non-invasive and precise prediction of mean arterial pressure (MAP) based on a fully convolutional neural network (FCNN).

A high-precision blood pressure data acquisition system compliant with international metrological standards was used in conjunction with the ‘gold standard’ auscultation method to collect blood pressure and pulse waveform data from patients. True MAP values were derived via Gaussian fitting of pulse waveform data, constructing a traceable dataset. The FCNN was applied to this dataset to develop a novel MAP prediction method. Additionally, the predictive accuracy of the FCNN was compared with linear regression and conventional empirical formulas.

The mean squared errors (MSE) for MAP prediction using the FCNN, linear regression, and empirical formulas were 19.76, 21.40, and 30.97, respectively. The coefficients of determination (R²) were 0.90, 0.89, and 0.84, and the prediction accuracies were 0.90, 0.89, and 0.85, respectively.

By using systolic blood pressure, diastolic blood pressure, age, and arm circumference as input parameters, the FCNN-based MAP prediction method significantly reduces the bias of empirical formulas. This approach not only improves the accuracy of hemodynamic boundary condition acquisition but also contributes to refining the metrological traceability system of non-invasive blood pressure measurement.

To study the effect of medial collateral ligament (MCL) release on the squatting motion followling total knee arthroplasty (TKA) and provide reference data for ligament release during knee replacement surgery.

Based on CT and MRI images of a volunteer, a three-dimensional (3D) geometric anatomical model of the natural knee joint including bone tissues and major soft tissues was established. A finite element model of the artificial knee joint was established by simulating TKA surgery. The squatting motion after 30% release of the upper end, lower end, and both ends of the MCL was simulated, and motion characteristic data of the knee joint at flexion/extension angles from 0° to 135° were obtained.

The effects of ligament release at different locations on knee squatting motion varied. After releasing the lower end, the medial translation, posterior translation, superior translation, and adduction of the femur relative to the tibia increased by 13.74%, 3.83%, 9.74%, and 2.37%, respectively, while the external rotation decreased by 36.8%. After releasing the upper end, the medial translation and posterior translation increased by 10.65% and 10%, respectively, while the superior translation, adduction, and external rotation decreased by 4.52%, 33.89%, and 67.1%, respectively. After releasing both ends, the medial translation, posterior translation, and superior translation increased by 14.77%, 9.39%, and 22.56%, respectively, while the adduction and external rotation decreased by 15.62% and 47.3%, respectively.

After MCL released, the medial translation, anterior translation, superior translation, and abduction of the femur relative to the tibia increased, while the external rotation decreased. Releasing the lower end had the least effect on these femoral movements, showing an obvious advantage.

The biological characteristics and action mechanisms underlying the excellent performance of skeletal muscles were studied through experiments to provide a scientific basis for the development of flexible actuators with performance comparable to that of skeletal muscles.

A frog skeletal muscle sample was contracted by applying electrical stimulation, and then tensile load was applied to it to analyze the relationship between the driving properties (such as contraction length and output force) of skeletal muscle and its structure from three aspects: skeletal muscle dimensions, tendon, and epimysium.

The contraction lengths of these skeletal muscle samples were approximately 28.92% and 20% under unloaded conditions and under 50% of their maximum output force, respectively. When the load on the skeletal muscles did not exceed 20% of their maximum output force, they also exhibited the property of rapid reduction (approximately 1.25 s). The active tendon increased contraction by approximately 19.68% compared with the inactive tendon, and the integrity of the epimysium protected the force transfer efficiency of skeletal muscles.

By simulating the structural and biomechanical properties of skeletal muscles, flexible actuators can achieve better driving performance, thus greatly promoting the development of bionic robots.

To analyze the fluid resistance characteristics of different drafting formations in marathon swimming using computational fluid dynamics (CFD) method, and provide theoretical guidance for selecting optimal drafting strategies in competitions and training.

Multi-swimmer models were established via three-dimensional body scanning technology, and various formation models (I-, A-, V-, L-, H-type) were created by adjusting lateral and longitudinal distances between swimmers. The ANSYS Discovery Live software was used to simulate the overall resistance of different models and the resistance of individual swimmers within formations.

The I3-type formation exhibited an overall drag reduction effect, reducing total resistance by 55.21%, whereas other formations increased overall resistance. The V-type formation showed the most significant resistance increase (31.88%). During drafting, the lowest resistance position was the rear position in the I3-type formation, while the highest resistance position was the middle position in the L-type formation. When leading, the fluid resistance of the leading swimmer in the A-type formation was significantly greater than that of an individual swimmer (P<0.05).

Longitudinal drafting formations demonstrated superior drag reduction effects, with the rear position in a three-person longitudinal arrangement showing the optimal drag reduction. Considering both tactical considerations and drag reduction effects, swimmers are advised to avoid the middle position in lateral formations.

To explore the impact of vision impairment (VI) on the gait of hemiplegic patients, assess their walking ability and fall risks, and provide a basis for developing effective rehabilitation strategies.

Thirty hemiplegic patients were enrolled and stratified by the severity of visual acuity impairment into three groups (unimpaired, mildly impaired, and severely impaired). The gait data of patients under uncorrected vision were collected using the Qualisys motion capture system and the Kistler three-dimensional force platform, and the balance ability of patients was assessed simultaneously. Subsequently, the gait and assessment data were statistically analyzed to compare inter-group differences.

Compared with the visually unimpaired group, significant differences in step length, symmetry, and walking speed were observed in hemiplegic patients of the mild visual impairment group and severe visual impairment group. As VI increased, gait abnormalities became more pronounced, with a longer double-limb support phase, a longer swing phase of the affected limb, and a shorter single-limb support phase of the affected limb in the gait cycle. Compared with the visually unimpaired group, significant differences in center of pressure (COP) and COP symmetry were found between the mild visual impairment group and severe visual impairment group, with gait abnormalities intensifying. The Berg balance scale (BBS) scores showed that there was a significant difference between the visually unimpaired group and severe visual impairment group, indicating that the group with visual impairment had poorer balance ability.

VI has a significant negative impact on the gait and walking ability of hemiplegic patients. This study emphasizes the importance of focusing on the impact of VI in the rehabilitation of hemiplegic patients, with regular vision assessments and personalized interventions being conducted, which are of great significance in enhancing patients' walking quality.

To analyze the effects and differences of two veno-arterial extracorporeal membrane oxygenation (VA-ECMO) cannulation methods and subsequent left ventricular unloading on cardiac function and hemodynamics.

The lumped parameter model (LPM) of VA-ECMO integrated with the cardiovascular system in the MATLAB/Simulink environment was extended to simulate and analyze the changes in ventricular function and blood flow in the heart failure patient model under central VA-ECMO or peripheral VA-ECMO support. The effects of using arterial vasodilators or a left atrial drainage cannula on left ventricular function under central VA-ECMO support at a pump flow rate of 3 L/min were compared.

Under central VA-ECMO or peripheral VA-ECMO support, left ventricular pressure and volume increased, and stroke volume and ventricular work decreased. Both arterial vasodilators and the left atrial drainage cannula could reduce left ventricular pressure and volume. Arterial vasodilators additionally increased stroke volume and improved left ventricular ejection fraction from 11.6% to 19.5%.

Both VA-ECMO cannulation methods provide effective circulatory support in the heart failure patient model, with similar effects on ventricular function. Under central VA-ECMO support, arterial vasodilators can improve left ventricular function more effectively than the left atrial drainage cannula.

To study how lipid bilayer fluidity modulates the interaction between β1 integrin and CD40L, as well as the formation of CD40L-mediated tumor cell contact interfaces.

Supported lipid bilayers (SLB) with different fluidities were prepared through adjusting the 1, 2-dioleoyl-sn-glycero-3-[N-(5-amino-1-carboxypentyl) iminodiacetic acid] succinyl nickel salt (DGS-NTA) content. The functionalization of lipid bilayers was achieved by anchoring fluorescently labeled CD40L molecules onto the membrane surface. The contact interface formation of PC9 cells on the functionalized lipid bilayers was observed through confocal fluorescence imaging and fluorescence recovery after photobleaching (FRAP) experiments, and data of two dimensional (2D) reaction kinetics of β1 integrin and CD40L were extracted from Zhu-Golan plots.

The diffusion coefficient of molecules in lipid bilayer was negatively correlated with DGS-NTA content. High fluidity of lipid bilayer promoted CD40L accumulation at cell contact interface and expanded the cell contact area. The 2D dissociation constants (2D K_d) of β1 integrin-CD40L complexes were approximately 13, 31 and 65 molecules/μm² for the three lipid bilayers with high, moderate and low fluidities, respectively.

High fluidity of lipid bilayers significantly facilitates diffusion and aggregation of CD40L to the cell contact interface, thus enhancing β1 integrin-CD40L interaction and the stability of cell contact interfaces.