Molecular alterations of human lumbar yellow ligament related to the process of intervertebral disk degeneration and stenosis

Percutaneous endoscopic lumbar discectomy via the medial foraminal and interlaminar approaches: A comparative study with 2-year follow-up

OBJECTIVE

The purpose of this study was to analyze the clinical effect of percutaneous endoscopic medial foraminal discectomy (PEMFD) in the treatment of lumbar disc herniation (LDH).

METHODS

We retrospectively examined and compared clinical data from 39 single-level LDH patients who underwent PEID and 47 who underwent PEMFD. All the patients were diagnosed with single-level LDH and were treated in Xuzhou Central Hospital for single-segmental lumbar disc herniation between June 2017 and December 2019. Collect and count surgical-related indicators, intraoperative bleeding volume and 24-hour postoperative drainage volume, lower extremity numbness Visual Analogue Scale (VAS), the pain VAS and lumbar Oswestry Disability Index (ODI) scores.

RESULTS

Intraoperative bleeding volume and 24-hour postoperative drainage volume were significantly lower in the PEMFD group (p < 0.05). Operation time and length of hospital stay did not significantly differ between the groups. Transient spinal cord injury and surgical site infection did not occur. Recurrence occurred in two patients in each group. Repeat surgery in these patients demonstrated remarkable epidural scarring in the PEID group patients; no scarring was evident in the PEMFD group patients. The numbness VAS score 72 h after surgery and the pain VAS and ODI scores 1 month after surgery significantly differed between groups; however, pain VAS and ODI scores 6, 12, and 24 months after surgery did not. At last follow-up, the modified MacNab criteria outcome did not significantly differ between the groups.

CONCLUSION

PEMFD and PEID have similar short- and medium-term outcomes. However, PEMFD has several advantages: simplicity, lower bleeding volume, and preservation of the LF.

Immune cell infiltration and the genes associated with ligamentum flavum hypertrophy: Identification and validation

Ligamentum flavum hypertrophy (LFH) is a common cause of spinal stenosis. The aim of the current study was to identify the differentially expressed genes (DEGs) in LFH and the molecular mechanisms underlying the development of and immune responses to LFH. The gene expression omnibus (GEO) database was used to obtain the GSE113212 dataset, and the DEGs were derived from microarray data. To identify critical genes and signaling pathways, gene ontology enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, and protein-protein interaction (PPI) network analyses were performed, followed by immune cell infiltration and Friends analyses using the retrieved datasets. The results were validated using quantitative real-time PCR. The 1530 DEGs identified comprised 971 upregulated and 559 downregulated genes. KEGG analysis revealed that DEGs were mostly enriched in the PI3K-Akt signaling pathway, while PPI network analysis identified tumor necrosis factor, interleukin (IL)-6, IL-10, epidermal growth factor receptor, and leptin as important nodes, which was validated by qPCR and IHC in human LFH tissues in vitro. A significant positive correlation was found between key LFH immune-related DEGs and several immune cell types, including T and B cells. The findings of the present study might lead to novel therapeutic targets and clinical approaches, as they provide insights into the molecular mechanisms of LFH.

Relationship between the location of ligamentum flavum hypertrophy and its stress in finite element analysis

Objective

To quantitatively describe the stress of the ligamentum flavum (LF) using the finite element method and to compare the stress at different parts of the healthy LF.

Methods

Based on the high resolution computed tomography imaging data of a healthy 22‐year‐old man, three‐dimensional nonlinear L_4–5 lumbar finite element model (FEM) representing intact condition was developed. The LF, as the object of the present research, was incorporated into the spinal model in the form of solid three‐dimensional structure. The model’s validity is verified by comparing its biomechanical indices, such as range of motion and axial compression pressure displacement, with published results under specific loading conditions. To authenticate the accuracy of the solid LF, the lamina attachments, the central cross‐section, and other anatomy indicators were compared with figures in the published literature. After the average and maximum von Mises stress on the surface of LF under various working conditions were measured using ANSYS and AutoCAD software, the surface stress difference in the LF between the ventral and dorsal sides as well as the lateral and lamina parts were determined.

Results

The FEM predicted a similar tendency for biomechanical indices as shown in previous studies. The lamina attachments, the central cross‐section, and the height as well as the width of the LF in the healthy FEM were in accordance with published results. In the healthy model, the average and maximum von Mises stress in the shallow layer of the LF were, respectively, 1.40, 2.28, 1.76, 1.48, 1.38 and 1.79, 2.41, 1.46, 1.42, 1.71 times that in the deep layer under a compressive preload of 500 N incorporated with flexion, extension, and lateral and rotational moments (10 Nm). The most conspicuous difference in surface stress was observed with the flexion motion, with a nearly 241% difference in the maximum stress and a 228% difference in the average stress compared to those in other states. As far as the whole dorsal side of the LF was concerned, the maximum surface stress was almost all concentrated in the dorsal neighboring facet joint portion. In addition, the maximum and average stress were, respectively, 77%, 72%, 15%, 11%, 71% and 153%, 39%, 54%, 200%, 212% higher in the lateral part than in the lamina part.

Conclusion

Based on the predisposition of LF hypertrophy in the human spine and the stress distribution of this study, the positive correlation between LF hypertrophy and its stress was confirmed.