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Abstract The transpedicular procedure has been widely used in spinal surgery. The determination of the best entry point is the key to perform a successful transpedicular procedure. Various techniques have been used to determine this point, but the results are variable. This study was carried out to determine the posterior endpoint of the lumbar pedicle central axis on the standard anterior–posterior (AP) fluoroscopic images. Computer-aided design technology was used to determine the pedicle central axis and the posterior endpoint of the pedicle central axis on the posterior aspect of the vertebra. The standard AP fluoroscopic image of the lumbar vertebral models by three-dimensional printing was achieved. The endpoint projection on the AP fluoroscopic image was determined in reference to the pedicle cortex projection by the measurements of the angle and distance on the established X–Y coordinate system of the radiologic image. The projection of posterior endpoint of the lumbar pedicle central axis were found to be superior to the X-axis of the established X–Y coordinate system and was located on the pedicle cortex projection on the standard AP fluoroscopic image of the vertebra. The projection point was distributed in different sectors in the coordinate system. It was located superior to the X-axis by 18° to 26° at L1, while they were located superior to the X-axis by 12° to 14° at L2 to L5. The projections of posterior endpoints of the lumbar pedicle central axis were located in different positions on the standard AP fluoroscopic image of the vertebra. The determination method of the projection point was helpful for selecting an entry point for a transpedicular procedure with a fluoroscopic technique.

BackgroundThe mortality rate in patients with ankylosing spondylitis (AS) and cervical fracture is relatively high.ObjectivesThis study aimed to investigate the instantaneous death risk and conditional survival (CS) in patients with AS and cervical fracture. We also studied the relationship between surgical timing and the incidence of complications.MethodsThis national multicentre retrospective study included 459 patients with AS and cervical fractures between 2003 and 2019. The hazard function was used to determine the risk of instantaneous death. The five-year CS was calculated to show the dynamic changes in prognosis.ResultsThe instantaneous death risk was relatively high in the first 6 months and gradually decreased over time in patients with AS and cervical fracture. For patients who did not undergo surgery, the instantaneous risk of death was relatively high in the first 15 months and gradually decreased over time. For patients with American Spinal Injury Association impairment scale (ASIA) A and B, the 5-year CS was 55.3% at baseline, and improved steadily to 88.4% at 2 years. Odds ratios (ORs) for pneumonia, electrolyte disturbance, respiratory insufficiency, and phlebothrombosis decreased as the surgery timing increased.ConclusionDeaths occurred mainly in the first 6 months after injury and gradually decreased over time. Our study highlights the need for continued surveillance and care in patients with AS with cervical fractures and provides useful survival estimates for both surgeons and patients. We also observed that early surgery can significantly increase functional recovery, and decrease the incidence of complications and rehospitalisation.

Osteoporosis bone defect is a refractory orthopaedic disease which characterized by impaired bone quality and bone regeneration capacity. Current therapies, including antiosteoporosis drugs and artificial bone grafts, are not always satisfactory. Herein, a strontium-substituted calcium phosphate silicate bioactive ceramic (Sr-CPS) was fabricated. In the present study, the extracts of Sr-CPS were prepared for in vitro study and Sr-CPS scaffolds were used for in vivo study. The cytocompatibility, osteogenic and osteoclastogenic properties of Sr-CPS extracts were characterized in comparison to CPS. Molecular mechanisms were also evaluated by Western blot. Sr-CPS extracts were found to promote osteogenesis by upregulating Wnt/β-catenin signal pathways and inhibit osteoclastogenesis through downregulating NF-κB signal pathway. In vivo, micro-CT, histological and histomorphometric observation were conducted after 8 weeks of implantation to evaluate the bone formation using calvarial defects model in ovariectomized rats. Compared with CPS, Sr-CPS significantly promoted critical sized ovariectomy (OVX) calvarial defects healing. Among all the samples, Sr-10 showed the best performance due to a perfect match of bone formation and scaffold degradation rates. Overall, the present study demonstrated that Sr-CPS ceramic can dually modulate both bone formation and resorption, which might be a promising candidate for the reconstruction of osteoporotic bone defect.

OBJECTIVE: The effect of Sox9 on the differentiation of bone marrow mesenchymal stem cells (BMSCs) to nucleus pulposus (NP)-like (chondrocyte-like) cells in vitro has been demonstrated. The objective of this study is to investigate the efficacy and feasibility of Sox9-transduced BMSCs to repair the degenerated intervertebral disc in a rabbit model. MATERIALS AND METHODS: Fifty skeletally mature New Zealand white rabbits were used. In the treatment groups, NP tissue was aspirated from the L2-L3, L3-L4, and L4-L5 discs in accordance with a previously validated rabbit model of intervertebral disc degeneration and then treated with thermogelling chitosan (C/Gp), GFP-transduced autologous BMSCs with C/Gp or Sox9-transduced autologous BMSCs with C/Gp. The role of Sox9 in the chondrogenic differentiation of BMSCs embedded in C/Gp gels in vitro and the repair effect of Sox9-transduced BMSCs on degenerated discs were evaluated by real-time PCR, conventional and quantitative MRI, macroscopic appearance, histology and immunohistochemistry. RESULTS: Sox9 could induce the chondrogenic differentiation of BMSCs in C/Gp gels and BMSCs could survive in vivo for at least 12 weeks. A higher T2-weighted signal intensity and T2 value, better preserved NP structure and greater amount of extracellular matrix were observed in discs treated with Sox9-transduced BMSCs compared with those without transduction. CONCLUSION: Sox9 gene transfer could significantly enhance the repair effect of BMSCs on the degenerated discs.