ObjectiveTo investigate the effectiveness of percutaneous double-segment lengthened sacroiliac screws internal fixation assisted by three-dimensional (3D) navigation technology in treatment of Denis type Ⅱ and Ⅲ sacral fractures. Methods A clinical data of 45 patients with the Denis type Ⅱ and Ⅲ sacral fractures admitted between January 2017 and May 2020 was retrospectively analyzed. There were 31 males and 14 females, with an average age of 48.3 years (range, 30-65 years). The pelvic fractures were all high energy injuries. According to the Tile classification standard, there were 24 cases of type C1, 16 cases of type C2, and 5 cases of type C3. The sacral fractures were classified as Denis type Ⅱ in 31 cases and type Ⅲ in 14 cases. The interval between injury and operation was 5-12 days (mean, 7.5 days). The lengthened sacroiliac screws were implanted in S1 and S2 segments respectively under the assistance of 3D navigation technology. The implantation time of each screw, the intraoperative X-ray exposure time, and the occurrence of surgical complications were recorded. After operation, the imaging reexamination was used to evaluate the screw position according to Gras standard and the reduction quality of sacral fractures according to Matta standard. At last follow-up, the pelvic function was scored with Majeed scoring standard. Results The 101 lengthened sacroiliac screws were implanted with the assisting of 3D navigation technology. The implantation time of each screw was 37.3 minutes on average (range, 30-45 minutes), and the X-ray exposure time was 46.2 seconds on average (range, 40-55 seconds). All patients had no neurovascular or organ injury. All incisions healed by first intention. The quality of fracture reduction was evaluated according to Matta standard as excellent in 22 cases, good in 18 cases, and fair in 5 cases, and the excellent and good rate was 88.89%. The screw position was evaluated according to Gras standard as excellent in 77 screws, good in 22 screws, and poor in 2 screws, and the excellent and good rate was 98.02%. All patients were followed up 12-24 months (mean, 14.6 months). All fractures healed and the healing time was 12-16 weeks (mean, 13.5 weeks). Pelvic function was evaluated according to Majeed scoring standard as excellent in 27 cases, good in 16 cases, fair in 2 cases, and the excellent and good rate was 95.56%. Conclusion Percutaneous double-segment lengthened sacroiliac screws internal fixation for the treatment of Denis type Ⅱ and Ⅲ sacral fractures is minimally invasive and effective. With the assistance of 3D navigation technology, the screw implantation is accurate and safe.
Cell migration is defined as the directional movement of cells toward a specific chemical concentration gradient, which plays a crucial role in embryo development, wound healing and tumor metastasis. However, current research methods showed low flux and are only suitable for single-factor assessment, and it was difficult to comprehensively consider the effects of other parameters such as different concentration gradients on cell migration behavior. In this paper, a four-channel microfluidic chip was designed. Its characteristics were as follows: it relied on laminar flow and diffusion mechanisms to establish and maintain a concentration gradient; it was suitable for observation of cell migration in different concentration gradient environment under a single microscope field; four cell isolation zones (20 μm width) were integrated into the microfluidic device to calibrate the initial cell position, which ensured the accuracy of the experimental results. In particular, we used COMSOL Multiphysics software to simulate the structure of the chip, which demonstrated the necessity of designing S-shaped microchannel and horizontal pressure balance channel to maintain concentration gradient. Finally, neutrophils were incubated with advanced glycation end products (AGEs, 0, 0.2, 0.5, 1.0 μmol·L−1), which were closely related to diabetes mellitus and its complications. The migration behavior of incubated neutrophils was studied in the 100 nmol·L−1 of chemokine (N-formylmethionyl-leucyl-phenyl-alanine) concentration gradient. The results prove the reliability and practicability of the microfluidic chip.
Reduced chemotactic migration of polymorphonuclear neutrophil (PMN) in sepsis patients leads to decreased bacterial clearance and accelerates the progression of sepsis disease. Quantification of PMN chemotaxis in sepsis patients can help characterize the immune health of sepsis patients. Microfluidic microarrays have been widely used for cell chemotaxis analysis because of the advantages of low reagent consumption, near-physiological environment, and visualization of the migration process. Currently, the study of PMN chemotaxis using microfluidic chips is mainly limited by the cumbersome cell separation operation and low throughput of microfluidic chips. In this paper, we first designed an inertial cell sorting chip to achieve label-free separation of the two major cell types by using the basic principle that leukocytes (mainly granulocytes, lymphocytes and monocytes) and erythrocytes move to different positions of the spiral microchannel when they move in the spiral microchannel under different strength of inertial force and Dean's resistance. Subsequently, in this paper, we designed a multi-channel cell migration chip and constructed a microfluidic PMN inertial label-free sorting and chemotaxis analysis platform. The inertial cell sorting chip separates leukocyte populations and then injects them into the multi-channel cell migration chip, which can complete the chemotaxis test of PMN to chemotactic peptide (fMLP) within 15 min. The remaining cells, such as monocytes with slow motility and lymphocytes that require pre-activation with proliferative culture, do not undergo significant chemotactic migration. The test results of sepsis patients (n=6) and healthy volunteers (n=3) recruited in this study showed that the chemotaxis index (CI) and migration velocity (v) of PMN from sepsis patients were significantly weaker than those from healthy volunteers. In conclusion, the microfluidic PMN inertial label-free sorting and chemotaxis analysis platform constructed in this paper can be used as a new tool for cell label-free sorting and migration studies.