Abstract The fracture of the prosthetic stem after prosthetic replacement of femoral head is not rare. In this study, the photoeastic instrument was used to study the stress distribution on the prosthetic stem following its insertion and to analyse the factors influencing the fracture of the stem. Through the examination of 9 places in 8 cases, it was found that:(1) The removal of femoral calcar and the inframedullary filling of the bone cement directly influenced the stress distribution. (2) The valgus or varus condition of the prosthesis would lead to stress concentration on the stem. (3) Once lossening of the prosthesis occured it would change the preliminary installingstress distribution in the upper femur which would lead to fatigue fracture. Ths experimental data and clinical observation would provide scientific basis forthe prevention of fracture of prosthetic stem following prosthetic replacement of femoral head.
The mechanical behavior modeling of human soft biological tissues is a key issue for a large number of medical applications, such as surgery simulation, surgery planning, diagnosis, etc. To develop a biomechanical model of human soft tissues under large deformation for surgery simulation, the adaptive quasi-linear viscoelastic (AQLV) model was proposed and applied in human forearm soft tissues by indentation tests. An incremental ramp-and-hold test was carried out to calibrate the model parameters. To verify the predictive ability of the AQLV model, the incremental ramp-and-hold test, a single large amplitude ramp-and-hold test and a sinusoidal cyclic test at large strain amplitude were adopted in this study. Results showed that the AQLV model could predict the test results under the three kinds of load conditions. It is concluded that the AQLV model is feasible to describe the nonlinear viscoelastic properties of in vivo soft tissues under large deformation. It is promising that this model can be selected as one of the soft tissues models in the software design for surgery simulation or diagnosis.
摘要:目的:研究老年患者动脉弹性功能与围术期血压变化的关系。方法:随机选择68例ASA分级Ⅰ－Ⅱ级行全麻手术的老年患者,根据检查所得动脉弹性的结果分为四组,分别是A组(C1、C2均正常),B组(C1异常,C2正常),C组(C1正常,C2异常),D组(C1、C2均异常)。测量其术前血压及全麻诱导8分钟后的血压水平。结果:〓动脉弹性功能不良的患者其术前MAP较高,且全麻诱导以后血压波动的比例较大。结论:高血压病的老年患者动脉弹性功能普遍降低;动脉弹性下降的老年病人全麻诱导后血压波动较大。Abstract: Objective:To investigate the relationship between the function of arterial elasticity and BP changes during perioperation in senile patients.Methods: 68 senile patients ASA class Ⅰor Ⅱ undergoing elective surgery under general anesthestia, were divided into four groups by evaluation of arterial elasticity (C1 was for large arterial elastic index and C2 for small. C1 and C2 were normal in group A, only C2 normal in group B, only C1 normal in group C, neither was normal in group D). Arterial blood pressure (BP) before operation and 8 min after induction were monitored and recorded. Results: Patients with dysfunction of arterial elasticity presented higher MAP during preoperation and significant BP changes after induction. Conclusion: Hypertension plays a key role in arterial elasticity.Arterial Blood Pressure of the senile patients with decreased arterial elasticity changes significantly after general anesthesia induction.
Objective To re-estimate price elasticity of different income groups’ demand for cigarette in terms of the lastest national tobacco consumption data and provide policy-makers with evidence to make decision on public policy of tobacco control. Methods A total of 16 056 adults of different income were surveyed in 27 provinces in 2002 and the data analyzed by using two-part model (logistic and log-linear model). Results We found that the demand elasticities were -0.589, -0.234, -0.017 and 0.247 for the poor group, low income group, middle income group and high income group, respectively. Conclusions Increasing tobacco tax will result in decreasing more cigarette consumption of lower income groups than higher groups, bearing more taxation of higher income groups than lower income groups, therefore tobacco taxation is not regressive.
ObjectiveTo identify risk factors for severe elastic recoil after percutaneous transluminal angioplasty (PTA) in the femoropopliteal artery disease based on intravascular ultrasound (IVUS) imaging and to develop a risk prediction model. MethodsA retrospective analysis was conducted on the clinical data from the patients with femoropopliteal artery disease treated at the First Affiliated Hospital of Chongqing Medical University from September 2020 to February 2022. Based on the IVUS images, a multivariate logistic regression analysis was conducted to identify the risk factors for severe elastic recoil in the patients with femoropopliteal artery disease after PTA. A nomogram prediction model was established to predict the occurrence of severe elastic recoil, and the area under receiver operating characteristic curve (AUC) was used to evaluate its ability to distinguish the occurrence of severe elastic recoil, which was validated using a calibration curve. ResultsA total of 34 patients with femoropopliteal artery disease who received PTA treatment were enrolled. Of the 803 vessel slices were analyzed, 451 (56.16%) demonstrated severe elastic recoil on IVUS imaging. The multivariate logistic regression analysis showed that the increased plaque burden, luminal eccentric index, external elastic membrane remodeling index, and the external elastic membrane-balloon area ratio were the risk factors for the occurrence of severe elastic recoil (P＜0.05). The AUC of the nomogram prediction model based on these risk factors exhibited moderate discrimination [AUC (95%CI)=0.775 (0.732, 0.818)]. The predicted probability of the nomogram model for severe elastic recoil was in a good agreement with the actual probability (P=0.862). ConclusionThe severe elastic recoil prediction model developed in this study, based on IVUS imaging data, can effectively identify high-risk factors for severe elastic recoil after PTA in patients with femoropopliteal artery disease, demonstrating a moderate predictive discrimination capability.
In the present study, swine thighbone samples with different water contents were prepared through process of dehydration. The influence of water content on the biotribological behavior of the bone tissue was studied with nanoindentation test, reciprocating sliding test and impact wear test. It is shown that the water contents had significant influence on the mechanical properties and biotribological behavior of the swine thighbone samples. In this experiment condition, with decreasing water content, the hardness and elastic modulus of the swine thighbone samples increased, while the tribological properties significantly decreased. The viscoelasticity of bone tissue decreased with decreasing water content, which mainly resulted in different wear mechanisms of the bone tissue samples under applied loading.
Polydimethylsiloxane (PDMS) and hydroxyapatite (HA) were combined in our laboratory to fabricate an elastic porous cell scaffold with pore-forming agent, and then the scaffold was used as culture media for rat bone marrow derived mesenchymal stem cells (rBMSCs). Different porous materials (square and circular in shape) were prepared by different pore-forming agents (NaCl or paraffin spheres) with adjustable porosity (62%-76%). The HA crystals grew on the wall of hole when the material was exposed to SBF solutions, showing its biocompatibility and ability to support the cells to attach on the materials.
ObjectiveTo explore the clinical features and EEG features of gelastic seizures, and analyze its value of lateral localization of epileptogenic area. MethodsAll patients with gelastic seizures admitted to the Sanbo Brain Hospital of Capital Medical University between January 2014 and December 2023 were reviewed and analyzed for history, symptomatology, imaging, electroencephalographic features and surgical protocols in patients who met the inclusion criteria and were followed up for at least 1 year, and surgical efficacy was assessed by using the Engel grading. ResultsA total of 51 patients with gelastic seizures were included, there were 32 (62.75%) males and 19 (37.25%) females, 21 (41.18%) with hypothalamic hamartomas (HH) and 30 (58.82%) with non-hypothalamic hamartomas. The age of onset was earlier in the HH group than in the non-HH group, with a median age of onset of 24.00 (0.00 ~ 96.00) and 78.00 (1.00 ~ 396.00) months (P<0.001). There are three types of laughter according to their characteristics: smiling or pleasant expressions, laughing out loud, crying or bitter laughter, with smiling or pleasant expressions being the most common (49.02%). Simple laughter is rare in all patients and is often accompanied by other manifestations such as autonomic symptoms, automatic movements, complex movements, and tonic seizures. Most of the HH group started with laughter whereas in the non-HH group laughter appeared mostly in the mid to late stages (P=0.007). Most of the HH group (57.14%) had preserved consciousness whereas most of the non-HH group (83.33%) had loss of consciousness (P=0.003). The interictal discharges in the HH group were mostly diffuse or multiregional, whereas those in the non-HH group were mostly regional (P=0.035). The onset of EEG during the seizure period in the HH group was mostly diffuse, whereas those in the non-HH group were mostly regional, mainly in the frontal and temporal regions, but there was no significant difference between the two groups (P=0.148). The non-HH group was mostly seen in those with definite lesions, and the most common type of lesion was FCD (focal cortical dysplasia, FCD). All patients enrolled in the group underwent surgical treatment, and stereoelectroencephalogram (SEEG) electrode implantation was performed in 13 cases in the HH group and in 17 cases in the non-HH group. 61.90% of the patients in the HH group had an Engel grade I, and 73.33% of the patients in the non-HH group had an Engel grade I. ConclusionsGelastic seizures has a complex neural network, with common causes other than hypothalamic hamartomas, and is most commonly seen in frontal or temporal lobe epilepsy, as well as in the insula or parietal lobe, with the most common type of lesion being FCD. The symptomatology, stage of onset, and electroencephalographic features of gelastic seizures can help in the differential diagnosis, and SEEG can help define the origin of the seizure and its diffusion pathway. The overall prognosis of surgical treatment was better in both the hypothalamic hamartomas and non-hypothalamic hamartomas groups.
The mechanical properties of the cornea in corneal ectasia disease undergo a significant reduction, yet the alterations in mechanical properties within distinct corneal regions remain unclear. In this study, we established a rabbit corneal ectasia model by employing collagenase II to degrade the corneal matrix within a central diameter of 6 mm. Optical coherence tomography was employed for the in vivo assessment of corneal morphology (corneal thickness and corneal curvature) one month after operation. Anisotropy and viscoelastic characteristics of corneal tissue were evaluated through biaxial and uniaxial testing, respectively. The results demonstrated a marked decrease in central corneal thickness, with no significant changes observed in corneal curvature. Under different strains, the elastic modulus of the cornea exhibited no significant differences in the up-down and naso-temporal directions between the control and model groups. However, the cornea in the model group displayed a significantly lower elastic modulus compared to the control group. Specifically, the elastic modulus of the central region cornea in the model group was significantly lower than that of the entire cornea within the same group. Moreover, in comparison to the control group, the cornea in the model group exhibited a significant increase in both creep rate and overall deformation rate. The instantaneous modulus and equilibrium modulus were significantly reduced in the model cornea. No significant differences were observed between the entire cornea and the central cornea concerning these parameters. The results indicate that corneal anisotropy remains unchanged in collagenase-induced ectatic cornea. However, a significant reduction in viscoelastic properties is noticed. This study provides valuable insights for investigating changes in corneal mechanical properties within different regions of ectatic corneal disease.
ObjectiveTo review the research progress in the diagnosis and treatment of distal tibiofibular syndesmosis injury.MethodsThe recent literature about distal tibiofibular syndesmosis injury was reviewed and analyzed.ResultsDistal tibiofibular syndesmosis injury is commonly seen in ankle joint injury, the anatomical complexities make diagnosis and treatment difficult. Preoperative physical examination, radiologic evaluation, and intraoperative stress-testing are important for the diagnosis. Aggressive treatment is also recommended for these injuries to prevent long-term chronic instability. Internal fixation is the main treatment, including metal screw, degradable screw, elastic fixation, and hybrid techniques. Metal screw fixation is still the current mainstream, but elastic fixation represented by Suture-button is more in line with the physiological characteristics of ankle joint, and the rate of secondary operation is low while the clinical outcome is satisfactory. The application prospect of elastic fixation is worthy of expectation.ConclusionIt’s crucial for patient with ankle fracture to repair the distal tibiofibular syndesmosis injury. How to diagnose the injury more accurately and simply, how to increase the success rate of reduction, and how to reduce the complications of surgery are still worthy for further exploration.