Biomechanical study of anterior transpedicular root screw intervertebral fusion system of lower cervical spine: a finite element analysis.

Background: The cervical anterior transpedicular screw (ATPS) fixation technology can provide adequate stability for cervical three-column injuries. However, its high risk of screw insertion and technical complexity have restricted its widespread clinical application. As an improvement over the ATPS technology, the cervical anterior transpedicular root screw (ATPRS) technology has been introduced to reduce the risk associated with screw insertion. This study aims to use finite element analysis (FEA) to investigate the biomechanical characteristics of a cervical spine model after using the novel ATPRS intervertebral fusion system, providing insights into its application and potential refinement. Methods: A finite element (FE) model of the C3-C7 lower cervical spine was established and validated. After two-level (C4-C6) anterior cervical discectomy and fusion (ACDF) surgery, FE models were constructed for the anterior cervical locked-plate (ACLP) internal fixation, the ATPS internal fixation, and the novel ATPRS intervertebral fusion system. These models were subjected to 75N axial force and 1.0 Nm to induce various movements. The range of motion (ROM) of the surgical segments (C4-C6), maximum stress on the internal fixation systems, and maximum stress on the adjacent intervertebral discs were tested and recorded. Results: All three internal fixation methods effectively reduced the ROM of the surgical segments. The ATPRS model demonstrated the smallest ROM during flexion, extension, and rotation, but a slightly larger ROM during lateral bending. Additionally, the maximum bone-screw interface stresses for the ATPRS model during flexion, extension, lateral bending, and axial rotation were 32.69, 64.24, 44.07, 35.89 MPa, which were lower than those of the ACLP and ATPS models. Similarly, the maximum stresses on the adjacent intervertebral discs in the ATPRS model during flexion, extension, lateral bending, and axial rotation consistently remained lower than those in the ACLP and ATPS models. However, the maximum stresses on the cage and the upper endplate of the ATPRS model were generally higher. Conclusion: Although the novel ATPRS intervertebral fusion system generally had greater endplate stress than ACLP and ATPS, it can better stabilize cervical three-column injuries and might reduce the occurrence of adjacent segment degeneration (ASD). Furthermore, further studies and improvements are necessary for the ATPRS intervertebral fusion system.

Association of anaemia on heart failure and left ventricular function: A bidirectional Mendelian randomization study.

AIMS: Observational studies have suggested that anaemia is associated with an increased risk of heart failure (HF). But the potential causal association is not clear. We aimed to investigate the association between anaemia and HF risk. METHODS AND RESULTS: A Mendelian randomization (MR) analysis was performed to confirm the causal association of anaemia with the risk of HF and left ventricular structure and function. Furthermore, a reverse-direction MR analyses was conducted to assess the causal effect of HF on anaemia. The MR analysis indicated that genetically predicted anaemia is associated with the increased risk of HF (meta: odd ratio (OR) = 1.12; 95% confidence interval (CI) [1.04, 1.20]; P = 0.002), and left ventricular mass index (ß = 1.051; 95% CI [0.384, 1.718]; P = 0.002), left ventricular mass (ß = 2.063; 95% CI [0.578, 3.547]; P = 0.006), left atrial minimum volume (ß = 0.076; 95% CI [0.008, 0.143]; P = 0.028), and left atrial maximum volume (ß = 0.090; 95% CI [0.023, 0.157]; P = 0.009). In the reverse-direction MR analyses, we found that genetic susceptibility to HF was significantly associated with the increased risk of anaemia (meta: OR = 1.40; 95% CI [1.24, 1.59]; P = 1.79 × 10-7 ). CONCLUSIONS: This MR study supports the genetic evidence that there is bidirectional causality between anaemia and the risk of HF as well as anaemia may cause left ventricular hypertrophy and enlargement of the left atrium. Considering the adverse causal effects between the two diseases, more attention should be paid to the prevention and treatment of anaemia in patients with HF.

The Advantages, Challenges, and Future of Human-Induced Pluripotent Stem Cell Lines in Type 2 Long QT Syndrome.

Type 2 long QT syndrome (LQT2) is the second most common subtype of long QT syndrome and is caused by mutations in KCHN2 encoding the rapidly activating delayed rectifier potassium channel vital for ventricular repolarization. Sudden cardiac death is a sentinel event of LQT2. Preclinical diagnosis by genetic testing is potentially life-saving.Traditional LQT2 models cannot wholly recapitulate genetic and phenotypic features; therefore, there is a demand for a reliable experimental model. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) meet this challenge. This review introduces the advantages of the hiPSC-CM model over the traditional model and discusses how hiPSC-CM and gene editing are used to decipher mechanisms of LQT2, screen for cardiotoxicity, and identify therapeutic strategies, thus promoting the realization of precision medicine for LQT2 patients.