Biomechanical changes in the proximal femur before and after removal of femoral neck system.

BACKGROUND: As an innovative internal fixation system, FNS (femoral neck system) is increasingly being utilized by surgeons for the treatment of femoral neck fractures. At present, there have been numerous finite element analysis experiments studying the immediate stability of FNS and CSS in treating femoral neck fractures. However, there is scarce mechanical analysis available regarding the effects post internal fixation removal. This study aimed to investigate the alterations in mechanical parameters of the proximal femur before and after the removal of FNS (femoral neck system), and to assess potential distinctions in indicators following the extraction of CSS (Cannulated Screws). METHODS: A proximal femur model was reconstructed using finite element numerical techniques. The models for CSS and FNS were formulated utilizing characteristics and parametric definitions. The internal fixation was combined with a normal proximal femur model to simulate the healing state after fracture surgery. Within the framework of static analysis, consistent stress burdens were applied across the entirety of the models. The total deformation and equivalent stress of the proximal femur were recorded before and after the removal of internal fixation. RESULTS: Under the standing condition, the total deformation of the model before and after removing CSS was 0.99 mm and 1.10 mm, respectively, indicating an increase of 12%. The total deformation of the model before and after removing FNS was 0.65 mm and 0.76 mm, respectively, indicating an increase of 17%. The equivalent stress for CSS and FNS were 55.21 MPa and 250.67 MPa, respectively. The average equivalent stress on the cross-section of the femoral neck before and after removal of CSS was 7.76 MPa and 6.11 MPa, respectively. The average equivalent stress on the cross-section of the femoral neck before and after removal of FNS was 9.89 MPa and 8.79 MPa, respectively. CONCLUSIONS: The retention of internal fixation may contribute to improved stability of the proximal femur. However, there still existed risks of stress concentration in internal fixation and stress shielding in the proximal femur. Compared to CSS, the removal of FNS results in larger bone tunnels and insufficient model stability. Further clinical interventions are recommended to address this issue.

Changes in the femoral trochlear induced with estradiol exposure, an experimental study on rats.

BACKGROUND: It is well known that estrogen is closely related to bone and joint tissue. Findings indicate that estradiol, injected during pregnancy, passes through the placental barrier and reaches the fetuses in utero where it exerts its action. Since trochlea appears well established in the prenatal period, however, whether trochlear dysplasia is related to estradiol exposure has not been confirmed, and the pathological process of estradiol exposure-induced trochlear dysplasia remains unclear. This study aimed to establish an estradiol exposure animal model in fetuses and to analyze the morphology of the femoral trochlear in neonatal rats. METHODS: 30 pregnant Wistar rats provided by the local Animal Center were assigned randomly into three groups, a high dose estradiol injection group, a low dose estradiol injection group and a blank control group. Gross, cross-sectional observation, histological staining measurement and microcomputed tomography of the rat offspring were conducted to evaluate the morphological changes of the femoral trochlea. RESULTS: The incidence of trochlear dysplasia increased with the concentration of estradiol injection. Gross and cross-sectional observation showed a shallower trochlea groove in two groups with estradiol injection. Histological staining measurement indicated that the trochlear sulcus angle and trochlear sulcus depth were significantly different between the two groups with estradiol injection and the blank control group at 0,5 and 10 days after birth. Subchondral bone loss was observed in the two estradiol injection groups by micro-CT, and the bone loss was found to deteriorate over time. CONCLUSION: In this study, estradiol exposure in fetuses had an adverse effect on intrauterine development and could induce trochlear dysplasia and bone loss in rat offspring. In addition, this study also showed that the higher concentration of estradiol injection in pregnant rats, the more incidence of trochlear dysplasia in rat offspring.

Identification of GINS1 as a potential prognostic biomarker for sarcoma using bioinformatic analysis.

Background: The GINS complex is related to cancer development, invasion, and poor prognosis in multiple tumors. In the study, we attempted to investigate the prognostic value of GINS1 in sarcoma patients. Methods: We analyzed GINS1 expression using Tumor IMmune Estimation Resource (TIMER) 2.0, Gene Expression Omnibus (GEO; GSE21122, GSE39262, and GSE21050), and The Cancer Genome Atlas (TCGA) databases. The prognostic value of GINS1 was explored using the survival and survminer packages of R. Genetic alteration analysis was investigated using cBioPortal. The Cell-type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) R script was used for the immunocyte infiltration analysis. MicroRNAs (miRNAs) targeting GINS1 were predicted using GEO (GSE69470) and MicroRNA Target Prediction Database (miRDB). Results: We found that GINS1 was overexpressed in sarcoma, especially in metastatic samples, and was associated with a worse prognosis. High GINS1 expression was a poor prognostic indicator for sarcoma patients. Moreover, GINS1 alteration was associated with worse survival of sarcoma patients. Immune infiltration analysis indicated that GINS1 expression was correlated with the infiltration of M0 and M2 macrophages in sarcoma. Finally, the miRNA hsa-miR-376a-3p was identified to potentially regulate GINS1 in sarcoma. Conclusions: These results indicate that GINS1 may be a promising prognostic biomarker and therapeutic target for sarcoma.

Biomechanical comparison of femoral neck system and cannulated screws coupled with medial plate for treating Pauwels III femoral neck fractures.

BACKGROUND: The femoral neck system (FNS) has been considered as a novel strategy for femoral neck fracture. The diversity of internal fixation creates difficulties in choosing an effective option for Pauwels III type femoral neck fractures. Therefore, it is significant to investigate the biomechanical effects of FNS versus conventional approaches on bones. OBJECTIVE: To evaluate the biomechanical characteristics of FNS versus cannulated screws coupled with medial plate (CSS+MP) for the treatment of Pauwels III type femoral neck fractures. METHODS: Through three-dimensional computer software (Minics, Geomagic - Warp), the proximal femur model was rebuilt. Based on the present clinical characteristics, models of internal fixation were reconstructed in SolidWorks, including cannulated screws (CSS), medial plate (MP) and FNS. After parameter setting and meshing, boundary conditions and loads were set up for the final mechanical calculation in Ansys Software. Under identical experimental conditions, such as the same Pauwels angle and force loading, the peak values of displacement, shear stress and equivalent (von Mises) stress were recorded. RESULTS: This study showed that the displacement of the models was CSS, CSS+MP, and FNS in descending order of magnitude. The shear stress and equivalent stress of the models was CSS+MP, FNS, and CSS in descending order. The principal shear stress of CSS+MP was concentrated on the medial plate. The equivalent stress of FNS was more dispersed and distributed from the proximal main nail to the distal locking screw. CONCLUSION: CSS+MP and FNS exhibited better initial stability compared to CSS. However, the MP was subjected to more shear stress, which could increase the risk of internal fixation failure. Due to its unique design, FNS may be a good choice for the treatment of Pauwels III type femoral neck fractures.

Mechanical effects of sagittal variations on Pauwels type III femoral neck fractures treated with Femoral Neck System(FNS).

BACKGROUND: The spatial position of internal fixation play a role in determining the stability of internal fixations, both in clinical practice and research. Researchers have examined the stability of FNS (Femoral neck system) in the presence of coronal plane changes. In our knowledge, due to the biomechanical limitations of the specimens, there are no mechanical studies on the sagittal variation of FNS. This study aimed to investigate the biomechanical behavior of sagittal variations on Pauwels type III femoral neck fractures treated with FNS through finite element analysis. METHODS: Finite element models including Pauwels type III femoral neck fracture and FNS were reconstructed. Five fracture models(superior, central, inferior, anterior, posterior) were created in accordance with the bolt location in the sagittal plane within the femoral head. Equivalent stress, shear stress, and total deformation of each model under the same physiological load were recorded. RESULTS: According to the results, the central model exhibited the slightest stress and displacement, with the exception of the superior model. The internal fixation stress of the superior model was smaller than that of the central model. However, the maximum interfragmentary stress, total deformation and shear resistance area of the superior model was larger than that of the central model. CONCLUSIONS: Central position of FNS in the sagittal plane allowed axial compression while reducing shear stress of internal fixation and interfragmentary equivalent stress. Off-axis fixation of the femoral neck increased the strain area and total displacement of the bone, raising the risk of fixation failure. Therefore, the central placement of FNS may be a better surgical target in the treatment of femoral neck fractures.

Impact of cage position on biomechanical performance of stand-alone lateral lumbar interbody fusion: a finite element analysis.

BACKGROUND: This study aimed to compare the biomechanical performance of various cage positions in stand-alone lateral lumbar interbody fusion(SA LLIF). METHODS: An intact finite element model of the L3-L5 was reconstructed. The model was verified and analyzed. Through changing the position of the cage, SA LLIF was established in four directions: anterior placement(AP), middle placement(MP), posterior placement(PP), oblique placement(OP). A 400 N vertical axial pre-load was imposed on the superior surface of L3 and a 10 N/m moment was applied on the L3 superior surface along the radial direction to simulate movements of flexion, extension, lateral bending, and axial rotation. Various biomechanical parameters were evaluated for intact and implanted models in all loading conditions, including the range of motion (ROM) and maximum stress. RESULTS: In the SA LLIF models, the ROM of L4-5 was reduced by 84.21-89.03% in flexion, 72.64-82.26% in extension, 92.5-95.85% in right and left lateral bending, and 87.22-92.77% in right and left axial rotation, respectively. Meanwhile, ROM of L3-4 was mildly increased by an average of 9.6% in all motion directions. Almost all stress peaks were increased after SA LLIF, including adjacent disc, facet joints, and endplates. MP had lower stress peaks of cage and endplates in most motion modes. In terms of the stress on facet joints and disc of the cephalad segment, MP had the smallest increment. CONCLUSION: In our study, SA LLIF risked accelerating the adjacent segment degeneration. The cage position had an influence on the distribution of endplate stress and the magnitude of facet joint stress. Compared with other positions, MP had the slightest effect on the stress in the adjacent facet joints. Meanwhile, MP seems to play an important role in reducing the risk of cage subsidence.

Epidemiologic characteristics of traumatic fractures in elderly patients during the outbreak of coronavirus disease 2019 in China.

PURPOSE: This study aimed to describe the epidemiologic characteristics of fracture in the elderly during the COVID-19. METHODS: This was a retrospective multi-centre study, which included patients who sustained fractures between 20 January and 19 February 2020. The collected data included patients' demographics (age and gender), injury-related (injury type, fracture location, injury mechanism, places where fracture occurred), and treatment modality. SPSS 23.0 was used to describe the data and perform some analysis. RESULTS: A total of 436 patients with 453 fractures were included; there were 153 males and 283 females, with an average age of 76.2 years (standard deviation, SD, 7.7 years; 65 to 105). For either males or females, 70-74 years was the most commonly involved age group. A total of 317 (72.7%) patients had their fractures occurring at home. Among 453 fractures, there were 264 (58.3%) hip fractures, accounting for 58.3%. Fall from standing height was the most common cause of fracture, making a proportion of 89.4% (405/453). Most fractures (95.8%, 434/453) were treated surgically, and 4.2% (19/453) were treated by plaster fixation or traction. Open reduction and internal fixation (ORIF) was the most used surgical method, taking a proportion of 49.2% (223/453). CONCLUSION: These findings highlighted the importance of primary prevention (home prevention) measures and could be used for references for individuals, health care providers, or health administrative department during the global pandemic of COVID-19.