Advanced topology of triply periodic minimal surface structure for osteogenic improvement within orthopedic metallic screw.

Metallic screws are one of the most common implants in orthopedics. However, the solid design of the screw has often resulted in stress shielding and postoperative loosening, substantially impacting its long-term fixation effect after surgery. Four additive manufacturing porous structures (Fischer-Koch S, Octet, Diamond, and Double Gyroid) are now introduced into the screw to fix those issues. Upon applying the four porous structures, elastic modulus in the screw decreased about 2∼15 times to reduce the occurrence of stress shielding, and bone regeneration effect on the screw surface increased about 1∼50 times to improve bone tissue regrowing. With more bone tissue regrowing on the inner surface of porous screw, a stiffer integration between screw and bone tissue will be achieved, which improves the long-term fixation of the screw tremendously. The biofunctions of the four topologies on osteogenesis have been fully explored, which provides an advanced topology optimization scheme for the screw utilized in orthopedic fixation.

Epidemiology and survival of patients with spinal meningiomas: a large retrospective cohort study.

INTRODUCTION: Spinal meningiomas (SMs) are relatively rare central nervous system tumors that usually trigger neurological symptoms. The prevalence of SMs is increasing with the aging of the global population. This study aimed to perform a systematic epidemiologic and survival prognostic analysis of SMs to evaluate their public health impact and to develop a novel method to estimate the overall survival at 3-year, 5-year, and 10-year in patients with SMs. METHODS: Five thousand one hundred fifty eight patients with SMs were recruited from the Surveillance, Epidemiology, and End Results (SEER) database from 2000 to 2019. Firstly, descriptive analysis was performed on the epidemiology of SMs. Secondly, these individuals were randomly allocated to the training and validation sets in a ratio of 7:3. Kaplan-Meier method and Cox regression analysis were utilized in the training set to identify independent prognostic factors and to construct a nomogram for survival prognosis. Subsequently, the discriminative power, predictive performance, and clinical utility of the nomogram were evaluated by receiver operating characteristic curve and decision curve analysis. Finally, a mortality risk stratification system and a web-based dynamic nomogram were constructed to quantify the risk of mortality in patients with SMs. RESULTS: The annual age-adjusted incidence rates of SMs increased steadily since 2004, reaching a rate of 0.40 cases per 100 000 population in 2019, with a female-to-male ratio of ~4:1. The age groups of 50-59, 60-69, and 70-79 years old were the most prevalent ages for SMs, accounting for 19.08, 24.93, and 23.32%, respectively. In addition, seven independent prognostic factors were identified to establish a prognostic nomogram for patients with SMs. The decision curve analysis and receiver operating characteristic curve indicated that the nomogram had high clinical utility and favorable accuracy. Moreover, the mortality risk stratification system effectively divided patients into low-risk, middle-risk, and high-risk subgroups. CONCLUSIONS: SMs are relatively rare benign spinal tumors prevalent in the white elderly female population. Clinicians could use the nomogram to personalize the prediction of the overall survival probability of patients with SMs, categorize these patients into different mortality risk subgroups, and develop personalized decision-making plans. Moreover, the web-based dynamic nomogram could help to further promote clinical application and assist clinicians in providing personalized counseling, timely monitoring, and clinical assessment for patients.

Prenatal exposure to emerging and traditional organophosphate flame retardants: Regional comparison, transplacental transfer, and birth outcomes.

During gestation, organophosphate flame retardants (OPFRs) have the potential to pose health risks to fetuses due to their ability to cross the placental barrier. However, data are scarce regarding the transplacental transfer of these compounds, particularly concerning emerging OPFRs and regional variations. In this study, we analyzed 14 traditional OPFRs and 5 emerging OPFRs in maternal and cord serum samples from Mianyang and Hangzhou, two cities in eastern and western China, respectively. The results revealed marked disparities in the overall levels of OPFRs between the two cities (p < 0.05), with the average concentration in maternal serum being higher in Hangzhou (14.55 ng/mL) than in Mianyang (8.28 ng/mL). The most abundant compounds found in both cities were tris (2-chloroethyl) phosphate (TCEP), Triphenyl phosphate (TPHP), and Tri-n-butyl phosphate (TnBP). Additionally, this study marked the first detection of novel OPFRs, including resorcinol bis (diphenyl phosphate) (RDP), isodecyl diphenyl phosphate (IDDPP), cresyl diphenyl phosphate (CDP), and bisphenol A bis (diphenyl phosphate) (BPA-BDPP) in maternal and cord serum simultaneously with the detection frequencies higher than 45%. This study also found that transplacental transfer efficiencies for OPFRs varied by ester group, with Aryl-OPFRs exhibiting the highest transfer rates (0.90-1.11) and Alkyl-OPFRs exhibiting the lowest (0.66-0.83). Transfer efficiencies exhibited a positive correlation with log Kow values (p < 0.05), suggesting that hydrophobic OPFRs with higher log Kow values are more likely to permeate the placental barrier. Moreover, the exposure levels of Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP), Tri (Chloropropyl) Phosphate (TCIPP), TPHP, and CDP in cord serum were negatively associated (p < 0.05) with birthweight of newborns. This research adds to our understanding of the transplacental transfer of OPFRs and the possible health risks associated with prenatal exposure.

Biomechanical evaluation of a novel individualized zero-profile cage for anterior cervical discectomy and fusion: a finite element analysis.

Introduction: Anterior cervical discectomy and fusion (ACDF) is a standard procedure for treating symptomatic cervical degenerative disease. The cage and plate constructs (CPCs) are widely employed in ACDF to maintain spinal stability and to provide immediate support. However, several instrument-related complications such as dysphagia, cage subsidence, and adjacent segment degeneration have been reported in the previous literature. This study aimed to design a novel individualized zero-profile (NIZP) cage and evaluate its potential to enhance the biomechanical performance between the instrument and the cervical spine. Methods: The intact finite element models of C3-C7 were constructed and validated. A NIZP cage was designed based on the anatomical parameters of the subject's C5/6. The ACDF procedure was simulated and the CPCs and NIZP cage were implanted separately. The range of motion (ROM), intradiscal pressure (IDP), and peak von Mises stresses of annulus fibrosus were compared between the two surgical models after ACDF under four motion conditions. Additionally, the biomechanical performance of the CPCs and NIZP cage were evaluated. Results: Compared with the intact model, the ROM of the surgical segment was significantly decreased for both surgical models under four motion conditions. Additionally, there was an increase in IDP and peak von Mises stress of annulus fibrosus in the adjacent segment. The NIZP cage had a more subtle impact on postoperative IDP and peak von Mises stress of annulus fibrosus in adjacent segments compared to CPCs. Meanwhile, the peak von Mises stresses of the NIZP cage were reduced by 90.0-120.0 MPa, and the average von Mises stresses were reduced by 12.61-17.56 MPa under different motion conditions. Regarding the fixation screws, the peak von Mises stresses in the screws of the NIZP cage increased by 10.0-40.0 MPa and the average von Mises stresses increased by 2.37-10.10 MPa. Conclusion: The NIZP cage could effectively reconstruct spinal stability in ACDF procedure by finite element study. Compared with the CPCs, the NIZP cage had better biomechanical performance, with a lower stress distribution on the cage and a more moderate effect on the adjacent segmental discs. Therefore, the NIZP cage could prevent postoperative dysphagia as well as decrease the risk of subsidence and adjacent disc degeneration following ACDF. In addition, this study could serve as a valuable reference for the development of personalized instruments.

Biomechanical effects of individualized artificial titanium alloy lamina implantation after laminectomy: A finite element analysis.

Background and objectives: Laminectomy is a common surgical procedure in spine surgery. However, disruption of the posterior ligamentous complex of the spine may lead to a range of postoperative complications. Artificial lamina as a kind of bionic implant can well restore the posterior spinal structure. In this study, an individualized artificial titanium alloy lamina was designed to reconstruct the posterior spinal structure after laminectomy and explored its biomechanical effects, which could provide a theoretical basis for the clinical application of the artificial lamina. Methods: Three finite element models were constructed, namely the nonlinear and non-homogeneous intact model of the whole lumbar spine, the lumbar decompression alone surgical model, and the artificial lamina implantation surgical model. The range of motion, intradiscal pressure, and annulus fibrosus peak stress were compared between the three models at the surgical and adjacent segments. The stresses of the artificial lamina and fixation screws were also analyzed for the four movement states. Results: Compared with the intact model, the lumbar decompression alone surgical model showed an increase in range of motion, intradiscal pressure, and annulus fibrosus peak stresses at the surgical segment and adjacent segments under all conditions. The artificial lamina implantation surgical model showed an increase in these measurements only in flexion, increasing by 7.5%-22.5%, 7.6%-17.9%, and 6.4%-19.3%, respectively, over the intact model, while there was little difference under other conditions. The peak stresses in both the screw and the artificial lamina were highest in axial rotation, i. e. 46.53 MPa and 53.84 MPa, respectively. Screw stresses were concentrated on the connection between the screw and the artificial lamina, and artificial lamina stresses were concentrated on the spinous root, around the screw hole, and the contact with the vertebral body. Conclusion: An individualized artificial titanium alloy lamina can effectively reduce the range of motion, intradiscal pressure, and annulus fibrosus stress at the surgical segment and adjacent segments. The application of artificial lamina could better preserve the biomechanical properties of the intact lumbar spine and reduce the risk of adjacent segmental disease.

Advanced strategies for constructing interfacial tissues of bone and tendon/ligament.

Enthesis, the interfacial tissue between a tendon/ligament and bone, exhibits a complex histological transition from soft to hard tissue, which significantly complicates its repair and regeneration after injury. Because traditional surgical treatments for enthesis injury are not satisfactory, tissue engineering has emerged as a strategy for improving treatment success. Rapid advances in enthesis tissue engineering have led to the development of several strategies for promoting enthesis tissue regeneration, including biological scaffolds, cells, growth factors, and biophysical modulation. In this review, we discuss recent advances in enthesis tissue engineering, particularly the use of biological scaffolds, as well as perspectives on the future directions in enthesis tissue engineering.

Biomaterials for Interbody Fusion in Bone Tissue Engineering.

In recent years, interbody fusion cages have played an important role in interbody fusion surgery for treating diseases like disc protrusion and spondylolisthesis. However, traditional cages cannot achieve satisfactory results due to their unreasonable design, poor material biocompatibility, and induced osteogenesis ability, limiting their application. There are currently 3 ways to improve the fusion effect, as follows. First, the interbody fusion cage is designed to facilitate bone ingrowth through the preliminary design. Second, choose interbody fusion cages made of different materials to meet the variable needs of interbody fusion. Finally, complete post-processing steps, such as coating the designed cage, to achieve a suitable osseointegration microstructure, and add other bioactive materials to achieve the most suitable biological microenvironment of bone tissue and improve the fusion effect. The focus of this review is on the design methods of interbody fusion cages, a comparison of the advantages and disadvantages of various materials, the influence of post-processing techniques and additional materials on interbody fusion, and the prospects for the future development of interbody fusion cages.