ObjectiveTo observe the changes in the biomechanical properties of the cornea of diabetic retinopathy (DR), and analyze its relationship with the degree of DR. MethodsA retrospective study. From September 2020 to February 2021, 83 patients with type 2 diabetes (T2DM) combined with DR treated in the Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, 83 eyes (DR group), 30 patients with T2DM without DR recruited from the outpatient clinic 30 eyes (NDR group) and 30 eyes of non-diabetes patients (NDM group) were included in the study. All left eyes were chose as the study eye. Among the 83 eyes in the DR group, 39 eyes were non-proliferative DR (NPDR) and 44 eyes were proliferative DR (PDR). Based on this, they were divided into NPDR group and PDR group. There was no statistically significant difference in age (t=1.10) and sex ratio (χ2=0.46) among patients in the DR group, NDR group, and NDM group (P>0.05); body mass index (t=3.74), glycosylated hemoglobin (t=35.02) and the length of the eye axis (t=5.51), the difference was statistically significant (P<0.05). The eye response analyzer (ORA) was used to measure the corneal hysteresis (CH), corneal resistance factor (CRF), Goldman related intraocular pressure (IOPg), and corneal compensatory intraocular pressure (IOPcc). The corneal topography was used to measure the central corneal thickness (CCT) of the examined eye. The differences of CCT, IOPcc, IOPg, CH, CRF among multiple groups were compared by one-way analysis of variance. Multiple linear regression was used to analyze the relationship between CH, CRF and related influencing factors in DR patients. ResultsThere were statistically significant differences in CCT, IOPcc, IOPg, CH, and CRF among the eyes of the DR group, NDR group, and NDM group (F=3.71, 5.60, 9.72, 9.02, 21.97; P<0.05). Pairwise comparisons were between groups, CH, CRF: the difference between the DR group and the NDM group and the NDR group was statistically significant (P<0.05); CCT: the difference between the DR group and the NDM group was statistically significant (P<0.05), and The difference in the NDR group was not statistically significant (P>0.05). CCT, CH, CRF: the difference between the NDR group and the NDM group was not statistically significant (P>0.05). The results of multiple linear regression analysis showed that CCT and IOPcc in DR patients were independent influencing factors of CH [CCT: β=0.01, 95% confidence interval (CI) 0.01-0.03, P=0.013; IOPcc: β=－0.15, 95%CI －0.25-－0.05, P=0.005]; Age, CCT, IOPcc were independent influencing factors of CRF [Age: β=－0.06, 95%CI －0.09-－0.03, P＜0.001; CCT: β=0.01, 95%CI 0.00-0.02, P=0.049; IOPcc: β=0.16, 95%CI 0.07-0.25, P=0.001]. The comparison of CCT, CH, CRF, adjusted CH, and adjusted CRF of the eyes in the NDR group, NPDR group, and PDR group were statistically significant (F=3.76, 5.36, 12.61, 6.59, 10.41; P<0.05). Pairwise comparison between groups, CH, CRF, adjusted CH, adjusted CRF: the difference between the NPDR group, the PDR group and the NDR group was statistically significant (P<0.05), and the difference between the PDR group and the NPDR group was not statistically significant (P>0.05); CCT: The difference between NPDR group and NDR group, PDR group and NPDR group was not statistically significant (P>0.05), and the difference between PDR group and NDR group was statistically significant (P<0.05). ConclusionThe CH and CRF of eyes with T2DM and DR are elevated; CCT and IOPcc are independent influencing factors of CH, and age, CCT and IOPcc are independent influencing factors of CRF.
ObjectiveTo compare the biomechanical characteristics of self-made nickel-titanium shape memory alloy stepped plate with calcaneal plate and cannulated compression screws in fixing calcaneal osteotomy.MethodsCalcaneal osteotomy was operated on 6 fresh-frozen lower limbs collected from donors. Then three kinds of fixation materials were applied in random, including the self-made nickel-titanium shape memory alloy stepped plate (group A), calcaneal plate (group B), and cannulated compression screws (group C). Immediately after fixation, axial loading of 20-600 N and 20 N/s in speed was introduced to record the biomechanical data including maximum displacement, elastic displacement, and maximum load. Then fatigue test was performed (5 Hz in frequency and repeat 3 000 times) and the same axial loading was introduced to collect the biomechanical data. Finally, the axial compression stiffness before and after fatigue test were calculated.ResultsThere was no significant difference in the axial compression stiffness between pre- and post-fatigue test in each group (P>0.05). However, the axial compression stiffness was significant higher in group A than that in groups B and C both before and after fatigue test (P<0.05). No significant difference was found between group B and group C (P>0.05).ConclusionSelf-made nickel-titanium shape memory alloy stepped plate is better than calcaneal plate and cannulated compression screws in axial load stiffness after being used to fix calcaneal osteotomy.
Based on force sensing resistor(FSR) sensor, we designed insoles for pressure measurement, which were stable and reliable with a simple structure, and easy to wear and to do outdoor experiments with. So the insoles could be used for gait detection system. The hardware includes plantar pressure sensor array, signal conditioning unit and main circuit unit. The software has the function of data acquisition, signal processing, feature extraction and classification function. We collected 27 groups of gait data of a healthy person based on this system to analyze the data and study pressure distribution under various gait features, i.e. walking on the flat ground, uphill, downhill, up the stairs, and down the stairs. These five gait patterns for pattern recognition and classification by K-nearest neighbors (KNN) recognition algorithm reached up to 90% accuracy. This preliminarily verified the usefulness of the system.
Diabetic retinopathy (DR) is a common complication of diabetes that can lead to visual impairment or even blindness. Current treatments mainly rely on invasive methods, which carry the risk of complications, making early intervention crucial. In recent years, research has revealed that the mechanical microenvironment of the retina plays a key role in the development and progression of DR, involving cell migration, functional disorders, and changes in the extracellular matrix. Mechanobiological mechanisms, such as mechanical signal transduction and the Hippo/Yes-associated protein pathway, are gradually being uncovered. Mechanical diagnostic and therapeutic strategies, including optical coherence elastography, tissue engineering, and intelligent diagnostic systems, offer new directions for DR management. In the future, further integration of biomechanics and mechanobiology research is needed to build multi-scale mechanical models and explore the synergistic regulation mechanisms between mechanical and biochemical factors, aiming to achieve precise and personalized diagnosis and treatment of DR and ultimately improve patients’ visual outcomes.
This study aimed to investigate biomechanical properties of synthetic implants for reconstructive surgery of pelvic floor dysfunction. In this dissertation, we chose four synthetic implants, i.e. total pelvic floor repair system (PROLIFT), gynecone TVT obtutator system (TVT-O), intra-vaginal sling placement device (IVS) and acellular dermal matrix (Renov), for tensile test respectively. The biomechanical properties of four synthetic implants were measured and analyzed using a material testing machine (Instron 4302 versatile material testing machine). The biomechanical parameters included ultimate stress strength, modulus of elasticity, maximum load and maximum elongation. The results showed that the maximum load of the four symthetic implants was TVT-O > IVS > PROLIFT > Renov, and the maximum load of TVT-O was significantly higher than PROLIFT and Renov ( P < 0.05). The ultimate stress strength was TVT-O > IVS > PROLIFT > Renov, with no significant differences among them ( P > 0.05). The maximum elongation of the four implants was TVT-O > PROLIFT > IVS > Renov, and the maximum elongation of TVT-O and PROLIFT were both significantly higher than Renov ( P < 0.05). The modulus of elasticity was IVS > Renov > TVT-O > PROLIFT, with no significant differences among them ( P > 0.05). Taken together, the present study demonstrates that the modulus of elasticity of IVS was the highest in the four synthetic implants; TVT-O had the highest mechanical strength; The maximum load, ultimate stress strength and maximum elongation of Renov were all the lowest; The mechanical properties of PROLIFT was the most stable, and its modulus of elasticity was the lowest in the four synthetic implants, which had good extensibility and elasticity. Therefore, it is necessary to pay attention to the biomechanical properties of new pelvic reconstructive materials for the clinical pelvic reconstructive surgery.
The dynamic analysis of the implantation process of a new vena cava filter was carried out by finite element analysis method to reveal the influence of the angle, length, width and thickness of the filter rod on its mechanical properties and the inner wall of the blood vessel. The results showed that the high-stress and high-strain areas of the filter were mainly concentrated in the connection between the filter rod and the filter wire. With the increase of the angle of the filter rod, the maximum equivalent stress and the maximum elastic strain on the filter wall decreased, while the maximum equivalent stress on the vascular wall increased. With the increase of the length of the filter rod, the maximum equivalent stress and strain peak of the filter wall increased, but the maximum equivalent stress of the vessel wall decreased. With the increase of the width and thickness of the filter rod, the maximum equivalent stress of the filter wall, the maximum elastic strain and the maximum equivalent stress of the vessel wall all showed an upward trend. The static safety factor of all filter models was greater than 1, and the structure after implantation was safe and reliable. The results of this study are expected to provide a theoretical basis for the structural optimization and deformation mechanism of the new type vena cava filter.
ObjectiveTo evaluate the stability of the fixation technique for the crossed rods consisting of occipital plate and C2 bilateral lamina screws by biomechanical test.MethodsSix fresh cervical specimens were harvested and established an atlantoaxial instability model. The models were fixed with parallel rods and crossed rods after occipital plate and C2 bilateral laminae screws were implanted. The specimens were tested in the following sequence: atlantoaxial instability model (unstable model group), under parallel rods fixation (parallel fixation group), and under crossed rods fixation (cross fixation group). The range of motion (ROM) of the C0-2 segments were measured in flexion-extension, left/right lateral bending, and left/right axial rotation. After the test, X-ray film was taken to observe the internal fixator position.ResultsThe biomechanical test results showed that the ROMs in flexion-extension, left/right lateral bending, and left/right axial rotation were significantly lower in the cross fixation group and the parallel fixation group than in the unstable model group (P<0.05). There was no significant difference between the cross fixation group and the parallel fixation group in flexion-extension and left/right lateral bending (P>0.05). In the left/right axial rotation, the ROMs of the cross fixation group were significantly lower than those of the parallel fixation group (P<0.05). After the test, the X-ray film showed the good internal fixator position.ConclusionThe axial rotational stability of occipitocervical fusion can be further improved by crossed rods fixation when the occipital plate and C2 bilateral lamina screws are used.
Bones are stained into red color with feeding madder, but we do not know whether the fed madder can change the bone biomechanical properties and bone mineral contents in animals. In this research, we established a rat model with feeding madder. The bone biomechanical properties were detected by universal material mechanics, bone mineral contents were detected by inductively coupled plasma mass spectrometry and spectrometer, and red color material in bone was analyzed by high performance liquid chromatography. The results showed that bone biomechanical parameters in femur diaphysis in the 10% and 15% group rats were significantly higher than those in the control group after feeding madder for 6 months. The level of calcium, magnesium and zinc in femur diaphysis in 10% and 15% group rats were higher than those in the control group after feeding madder for 6 months. However, it was shown that the kidney congestion andhyperemia and the level of blood urea nitrogen and creatinine in the 15% group rats were significantly different compared to those in the control group rats after feeding madder for 6 months. The red colored material in bone is related to alizarin analyzed with high-performance liquid chromatography. The conclusion could be drawn that feeding 10% madder in diet was not toxic to the rats fed for 6 months, and it could improve bone biomechanical properties and increase bone mineral elements.
Biomechanics-related degenerative lumbar spondylosis refers to the diseases of lumbar spine joints, muscles, fascia, and ligaments that related to maintaining lumbar spine mechanical balance and stability, which are mainly manifesting as lumbar pain and lumbocrural pain. The occurrence of biomechanics-related degenerative lumbar spondylosis is related to continuous static load and dynamic load, extra load, and aging. This article describes the etiology of biomechanics-related degenerative lumbar spondylosis, summarizes the functional compensation and structural compensation of losing balance by analyzing the characteristics of human biomechanical balance and the biomechanics of lumbar spondylolisthesis, and interprets the clinical classification of lumbar spondylosis, so as to provide a better reference for the diagnosis and treatment of lumbar spine diseases.
Objective To summarize the characteristics and biomechanical research progress of common acetabular reconstruction techniques in patients with Crowe type Ⅱ and Ⅲ developmental dysplasia of the hip (DDH) undergoing total hip arthroplasty (THA), and provide references for selecting appropriate acetabular reconstruction techniques for clinical treatment of Crowe type Ⅱ and Ⅲ DDH. Methods The domestic and foreign relevant literature on biomechanics of acetabular reconstruction with Crowe type Ⅱ and Ⅲ DDH was reviewed, and the research progress was summarized.Results At present, there are many acetabular reconstruction techniques in Crowe type Ⅱ and Ⅲ DDH patients undergoing THA, with their own characteristics due to structural and biomechanical differences. The acetabular roof reconstruction technique enables the acetabular cup prosthesis to obtain satisfactory initial stability, increases the acetabular bone reserve, and provides a bone mass basis for the possible secondary revision. The medial protrusio technique (MPT) reduces the stress in the weight-bearing area of the hip joint and the wear of the prosthesis, and increases the service life of the prosthesis. Small acetabulum cup technique enables shallow small acetabulum to match suitable acetabulum cup to obtain ideal cup coverage, but small acetabulum cup also increases the stress per unit area of acetabulum cup, which is not conducive to the long-term effectiveness. The rotation center up-shifting technique increases the initial stability of the cup. Conclusion Currently, there is no detailed standard guidance for the selection of acetabular reconstruction in THA with Crowe type Ⅱ and Ⅲ DDH, and the appropriate acetabular reconstruction technique should be selected according to the different types of DDH.