Does Cage Position Affect the Risk of Cage Subsidence After Oblique Lumbar Interbody Fusion in the Osteoporotic Lumbar Spine: A Finite Element Analysis.

OBJECTIVE: This study aimed to evaluate the biomechanical effects of different cage positions with stand-alone (SA) methods and bilateral pedicle screw fixation (BPSF) in the osteoporotic lumbar spine after oblique lumbar interbody fusion (OLIF). METHODS: A finite element model of an intact L3-L5 lumbar spine was constructed. After validation, an osteoporosis model (OP) was constructed by assigning osteoporotic material properties. SA models (SA1, SA2, SA3) and BPSF models (BPSF1, BPSF2, BPSF3) in which a cage was placed in the anterior, middle, and posterior third of the L5 superior endplate (SEP) were constructed at the L4-L5 segment of the OP. The L4-L5 range of motion (ROM), the stress of the L5 SEP, the stress of the cage, and the stress of fixation were compared among the different models. RESULTS: According to the degree of ROM of L4-L5, the stress of the L5 SEP and the stress of the cage for most physiological motions, the SA and BPSF models were ranked as follows: SA2 < SA1 < SA3, BPSF2 < BPSF1 < BPSF3. In BPSF2, the stress of fixation was minimal in most motions. At the same cage position, the ROM of L4-L5, the stress of the L5 SEP, and the stress of the cage in the BPSF models were significantly reduced compared with those in SA models; compared with SA2, BPSF2 had a maximum reduction of 83.24%, 70.71%, and 73.52% in these parameters, respectively. CONCLUSIONS: Placing the cage in the middle third of the L5 SEP for OLIF could reduce the maximum stresses of the L5 SEP, the cage, and the fixation, which may reduce the risk of postoperative cage subsidence, endplate collapse, and fixation fracture in the osteoporotic lumbar spine. Compared with SA OLIF, BPSF could provide sufficient stability for the surgical segment and may reduce the incidence of the aforementioned complications.

Identification of Characteristic Genes in Whole Blood of Intervertebral Disc Degeneration Patients by Weighted Gene Coexpression Network Analysis (WGCNA).

Intervertebral disc degeneration (IDD) is a major cause of lower back pain. However, to date, the molecular mechanism of the IDD remains unclear. Gene expression profiles and clinical traits were downloaded from the Gene Expression Omnibus (GEO) database. Firstly, weighted gene coexpression network analysis (WGCNA) was used to screen IDD-related genes. Moreover, least absolute shrinkage and selection operator (LASSO) logistic regression and support vector machine (SVM) algorithms were used to identify characteristic genes. Furthermore, we further investigated the immune landscape by the Cell-type Identification By Estimating Relative Subsets Of RNA Transcripts (CIBERSORT) algorithm and the correlations between key characteristic genes and infiltrating immune cells. Finally, a competing endogenous RNA (ceRNA) network was established to show the regulatory mechanisms of characteristic genes. A total of 2458 genes were identified by WGCNA, and 48 of them were disordered. After overlapping the genes obtained by LASSO and SVM-RFE algorithms, genes including LINC01347, ASAP1-IT1, lnc-SEPT7L-1, B3GNT8, CHRNB3, CLEC4F, LOC102724000, SERINC2, and LOC102723649 were identified as characteristic genes of IDD. Moreover, differential analysis further identified ASAP1-IT1 and SERINC2 as key characteristic genes. Furthermore, we found that the expression of both ASAP1-IT1 and SERINC2 was related to the proportions of T cells gamma delta and Neutrophils. Finally, a ceRNA network was established to show the regulatory mechanisms of ASAP1-IT1 and SERINC2. In conclusion, the present study identified ASAP1-IT1 and SERINC2 as the key characteristic genes of IDD through integrative bioinformatic analyses, which may contribute to the diagnosis and treatment of IDD.