BACKGROUND: The minimally invasive axial lumbar interbody approach (AxiaLIF) for L4–S1 fusion has been applied in America and Europe, and has obtained satisfactory curative efficacy. Because of significant anatomical differences between Chinese and Europeans and Americans, whether AxiaLIF is appropriate for Chinese remains unclear. Moreover,there are some problems in the application of AxiaLIF, so how to optimize AxiaLIF is a key to its promotion in China.OBJECTIVE: To provide anatomical data for the design of axial screws suitable for Chinese through measuring the mid axial line of the lateral lumbar radiograph and cross sections of L5 and S1 on lumbar CT in normal Chinese population.METHODS: The lateral lumbar radiographs from Chinese healthy population were selected, including 35 males and 30 females, the axial height of S1, the disc distance between L5 and S1, and the axial height of L5 were measured so as to provide anatomical data for designing the length of the axial screw. The transverse and sagittal diameters of L5 and S1 in the lumbar CT of 26 adult healthy males and 24 healthy females were measured to provide anatomical data for designing the diameter of the axial screw.RESULTS AND CONCLUSION: (1) The axial height of S1 in males and females was (26.76±3.94) mm and (22.91±2.91) mm, respectively (P < 0.05). The disc distance between L5 and S1 was (12.62±1.90) mm for males and (11.92±1.78) mm for females (P > 0.05). The axial height of L5 was (29.12±2.18) mm for males and (26.91±2.47) mm for females (P <0.05). (2) The transverse diameter of S1 was (49.14±4.14) mm for males and (46.11±4.44) mm for females (P < 0.05).The transverse diameter of L5 was (41.34±4.31) mm for males and (43.12±3.71) mm for females (P < 0.05). The sagittal diameter of L5 was (34.48±2.32) mm for males and (33.03±3.48) mm for females, and the sagittal diameter of S1 was (35.65±4.28) mm for males and (33.53±3.26) for females, (both P > 0.05). (3) That is to say, this study provides the anatomical data for designing the axial screws suitable for the lumbar fusion of Chinese by measuring the mid axial line of the lateral lumbar radiographs and the cross sections of L5 and S1 on lumbar CT. The image measurement method can be used to analyze the preoperative images of the patients to predict the feasibility of the surgical approach and pre-select the internal fixation model for personalized screw positioning.

OBJECTIVE: To investigate whether miR-125b regulates the osteogenic differentiation of bone marrow mesenchymal stem cells (MSCs) by modulating Smad4, a predicted target in silicon. METHODS: Smad4 3'-UTR-luciferase vector was constructed and dual-luciferase reporter gene assay was employed to examine the effect of miR-125b on luciferase activity. MSCs were isolated and cultured from human bone marrow, and then transfected with miR-125b mimics followed by induction of osteogenic differentiation. qRT-PCR and Western blot were used to detect the expressions of Smad4 mRNA and protein. MSCs were induced into the osteoblasts after transfecting with Smad4 siRNA, and the effect of Smad4 downregulation on osteogenic differentiation was observed by AKP activity and RUNX2 mRNA levels. RESULTS: miR-216b bound Smad4 3'-UTR and inhibited the luciferase activity (P<0.05). Smad4 mRNA and protein expressions were significantly down-regulated in the MSCs induced into osteogenic differentiation when miR-125b was overexpressed. Downregulation of Smad4 suppressed the AKP activity and RUNX2 mRNA expression, indicating that Smad4 siRNA simulated at least in part the function of miR-125b as the regulator of MSCs osteogenic differentiation. CONCLUSION miR-125b can suppress MSCs osteogenic differentiation by directly targeting Smad4.
Bone Marrow Cells ; cytology ; Cell Differentiation ; physiology ; Cells, Cultured ; Core Binding Factor Alpha 1 Subunit ; genetics ; metabolism ; Down-Regulation ; Female ; Humans ; Mesenchymal Stem Cells ; cytology ; MicroRNAs ; physiology ; Osteoblasts ; cytology ; Osteogenesis ; RNA, Messenger ; genetics ; metabolism ; RNA, Small Interfering ; genetics ; Smad4 Protein ; genetics ; metabolism ; Transfection ; Young Adult