OBJECTIVE: To investigate the biomechanical characteristics of Schatzker type Ⅱ tibial plateau fracture fixed by different bone grafting methods and internal fixations. METHODS: Twenty-four embalmed specimens of adult knee joint were selected to make Schatzker type Ⅱ tibial plateau fracture models, which were randomly divided into 8 groups (groups A1-D1 and groups A2-D2, n=3). After all the fracture models were restored, non-structural iliac crest bone grafts were implanted in group A1-D1, and structural iliac crest bone grafts in groups A2-D2. Following bone grafting, group A was fixed with a lateral golf locking plate, group B was fixed with lateral golf locking plate combined compression bolt, group C was fixed with lateral tibial "L"-shaped locking plate, and group D was fixed with lateral tibial "L"-shaped locking plate combined compression bolt. Compression and cyclic loading tests were performed on a biomechanical testing machine. A distal femur specimen or a 4-cm-diameter homemade bone cement ball were used as a pressure application mould for each group of models. The specimens were loaded with local compression at a rate of 10 N/s and the mechanical loads were recorded when the vertical displacement of the split bone block reached 2 mm. Then, compressive and cyclic loading tests were conducted on the fixed models of each group. The specimens were compression loaded to 100, 400, 700, and 1 000 N at a speed of 10 N/s to record the vertical displacement of the split bone block. The specimens were also subjected to cyclic loading at 5 Hz and 10 N/s within the ranges 100-300, 100-500, 100-700, and 100-1 000 N to record the vertical displacement of the split bone block at the end of the entire cyclic loading test. The specimens were subjected to cyclic loading tests and the vertical displacement of the split bone block was recorded at the end of the test. RESULTS: When the vertical displacement of the collapsed bone block reached 2 mm, the mechanical load of groups A2-D2 was significantly greater than that of groups A1-D1 ( P<0.05). The mechanical load of groups B and D was significantly greater than that of group A under the two bone grafting methods ( P<0.05); the local mechanical load of group D was significantly greater than that of groups B and C under the structural iliac crest bone grafts ( P<0.05). There was no significant difference ( P>0.05) in the vertical displacement of the split bone blocks between the two bone graft methods when the compressive load was 100, 400, 700 N and the cyclic load was 100-300, 100-500, 100-700 N in groups A-D. However, the vertical displacement of bone block in groups A1-D1 was significantly greater than that in groups A2-D2 ( P<0.05) when the compressive loading was 1 000 N and the cyclic load was 100-1 000 N. The vertical displacement of bone block in group B was significantly smaller than that in group A, and that in group D was significantly smaller than that in group C under the same way of bone graft ( P<0.05). CONCLUSION Compared with non-structural iliac crest bone grafts implantation, structural iliac crest bone grafts is more effective in preventing secondary collapse of Schatzker type Ⅱ tibial plateau fracture, and locking plate combined with compression bolt fixation can provide better articular surface support and resistance to axial compression, and the lateral tibial "L"-shaped locking plate can better highlight its advantages of "raft" fixation and show better mechanical stability.
Humans ; Bone Transplantation/methods* ; Tibial Fractures/physiopathology* ; Fracture Fixation, Internal/instrumentation* ; Biomechanical Phenomena ; Bone Plates ; Ilium/transplantation* ; Adult ; Tibia/surgery* ; Bone Cements ; Knee Joint/surgery* ; Male ; Tibial Plateau Fractures

Liver transplantation (LT) has become a standard treatment for end-stage liver diseases, and graft injury is intricately associated with poor prognosis. Granzyme B (GZMB) plays a vital role in natural killer (NK) cell biology, but whether NK-derived GZMB affects graft injury remains elusive. Through the analysis of single-cell RNA-sequencing data obtained from human LT grafts and the isolation of lymphocytes from mouse livers following ischemia-reperfusion injury (IRI), we demonstrated that 2NK cells with high expression of GZMB are enriched in patients and mice. Both systemically and liver-targeted depletion of NK cells led to a notable reduction in GZMB⁺ cell infiltration, subsequently resulting in diminished graft injury. Notably, the reconstitution of Il2rg ^-/- Rag2 ^-/- mice with purified Gzmb-KO NK cells demonstrated superior outcomes compared to those with wild-type NK cells. Crucially, global knockout of GZMB and pharmacological inhibition exhibited remarkable improvements in liver function in both mouse IRI and rat LT models. Moreover, a phosphorylated derivative of FDA-approved vidarabine was identified as an effective inhibitor of mouse GZMB activity by molecular dynamics, which could provide a potential avenue for therapeutic intervention. Therefore, targeting NK cell-derived GZMB during the LT process suggests potential therapeutic strategies to improve post-transplant outcomes.

Objective To explore the effect and potential mechanisms of melatonin combined with gemcitabine on the chemosensitivity of human pancreatic cancer cell line PANC-1.Methods Human pancreatic cancer cell line PANC-1 was trea-ted with gemcitabine alone or in combination with melatonin.Cell viability was assessed using CCK-8.Effect of melatonin and gem-citabine alone or in combination on the clonogenic capacity of PANC-1 cells were observed through colony formation experiments.Scratch assays and transwell experiments were conducted to evaluate cell migration ability.Reactive oxygen species(ROS)and mitochondrial membrane point JC-1 assay kit were used to determine reactive oxygen species synthesis and membrane potential levels.Intracellular Fe2+level was measured using ferrous ion fluorescent probe.The protein expression levels of LC3,P62,GPX4 and SLC7A11 in different treatment groups were detected by immunofluorescence and Western blotting.Results CCK-8 results showed that the viability of PANC-1 cells was inhibited by gemcitabine alone after 48 h and 72 h of treatment in a time-and dose-dependent manner.The cell viability of gemcitabine combined with melatonin group was significantly lower than that of gemcitabine group,and the cell viability decreased with the increase of melatonin concentration.Scratch assays,transwell experiments,and plate colony formation assay results demonstrated that the proliferation and migration of cells in the gemcitabine combined with the me-latonin group were significantly inhibited compared with the gemcitabine group.The levels of reactive oxygen species and Fe2+in PANC-1 in gemcitabine combined with the melatonin group were higher than those in the gemcitabine group,and the mitochondri-al membrane potential was significantly decreased(P＜0.01).Western blotting and immunofluorescence results showed that the ra-tio of autophagy-related protein LC3-Ⅱ/LC3-Ⅰ in gemcitabine combined with the melatonin group was lower than that in the gem-citabine group,and the expression of P62 was up-regulated,and the expression of anti-iron death-related protein GPX4 and SLC7A11 was significantly inhibited(P＜0.05),suggesting that melatonin combined with gemcitabine can inhibit autophagy and promote ferroptosis in PANC-1 cells.Conclusion Melatonin enhances the chemosensitivity of pancreatic cancer cell PANC-1 to gemcitabine by inhibiting autophagy and promoting ferroptosis of tumor cells.

Based on the analysis of heart rate variability(HRV),a prediction method for paroxysmal atrial fibrillation(PAF)attacks is proposed.A new adaptive filtering technique is used for smoothing and coarse graining of HRV,followed by entropy-based quantification of HRV complexity at multiple adaptive scales.After the features are normalized by Min-Max,feature subsets are selected by sequential forward selection method,and then input to support vector machine to identify HRV types and predict PAF attacks.Through 5-fold cross-validation on a set of 50 HRV sequences each lasting 5 minutes,the optimal prediction results are obtained:98%accuracy,100%sensitivity,96%specificity,demonstrating excellent performance.In addition,the experiment shows significant changes(P<0.05)in the complexity eigenvalues of HRV far away from and close to PAF at different frequency bands,reflecting alterations in nervous system regulation of cardiac rhythm and a decline in the ability to adapt to external environmental changes such as stress regulation.

Objective:To explore the role of arthroscopic exploration in the treatment of tibial plateau fractures with homeopathic double reverse traction reduction and internal fixation.Methods:A retrospective analysis was conducted on the data of 188 patients with tibial plateau fractures treated by homeopathic double reverse traction reduction assisted internal fixation and arthroscopic exploration at the Third Hospital of Hebei Medical University from January 2019 to December 2021. There were 129 males and 59 females, aged 46.7±11.8 years (range, 14-80 years); 115 cases on the left and 73 cases on the right. Schatzker classification of fractures: 81 cases of type II, 15 cases of type III, 23 cases of type IV, 29 cases of type V, and 40 cases of type VI. The time from injury to surgery was 1-14 days, with an average of 10±5 days. The surgery was performed with double reverse traction assisted reduction, locking bone plate and self-breaking compression bolt fixation. Then, arthroscopy was used to explore the quality of fracture reduction, meniscus and ligament damage, and the corresponding intra-articular lesions were treated, such as partial meniscus resection, complete meniscus resection, or suturing. The Rasmussen score was used to evaluate the quality of fracture reduction after surgery, and the Hospital for Special Surgery (HSS) knee joint score was used to evaluate the postoperative function of the knee joint.Results:All patients successfully completed fracture reduction, fixation, and arthroscopic exploration. The average surgical time was 95±21 min (range, 30-120 min); The average intraoperative bleeding volume was 120±58 ml (range, 50-300 ml). All patients were followed up for 10-24 months, with an average of 18±6.5 months. All patients' fractures achieved clinical healing after surgery, with a healing time of 2.5-6.0 months, with an average of 3±2.4 months. Among them, 165 patients (87.8%, 165/188) healed within 3 months after surgery, while the remaining 23 patients healed within 4-6 months after surgery. Arthroscopic exploration revealed that 188 patients had good fracture reduction and a flat articular surface. Among them, 97 cases (51.6%, 97/188) were complicated with meniscus injury, with longitudinal tear (29%, 28/97) being the most common, suture treatment was performed under arthroscopy; the remaining 69 patients underwent partial meniscectomy. All the patient's knee function recovered well at the last follow-up. 29 cases (15.4%, 29/188) were complicated with cruciate ligament injury, none of them underwent primary repair and were fixed with plaster or brace after operation. The Rasmussen score for the final follow-up after surgery was 16.8±2.4 points (range, 6-18 points), with 152 cases being excellent and 36 cases being good, with a 100% excellent and good rate. The HSS knee joint scores were 79.8±9.2 points, 85.1±10.1 points, and 94.9±7.6 points at 3, 6 months after surgery, and at the last follow-up, respectively, with statistically significant differences ( F=52.53, P<0.001). Superficial skin infection occurred in 2 cases after operation, which was cured by regular dressing change and anti-infection treatment with antibiotics. Deep vein thrombosis occurred in 7 cases within 1 week after operation, and low molecular weight heparin anticoagulation therapy was given. Conclusion:After using double reverse traction assisted reduction and internal fixation, arthroscopic examination can not only evaluate the quality of reduction for tibial plateau fractures, but also handle combined meniscus injuries and evaluate the condition of cruciate ligament injuries.

Objective:To evaluate the biomechanical stability of our slot-designed compression bolt (SCB) combined with bilateral locking compression plates (LCPs) in the treatment of intra-articular distal femur fracture.Methods:In 24 adult male knee specimens treated with formalin, the femoral bony part was preserved to establish standard models of intra-articular distal femur fracture (AO type 33-C1). According to the random number table, the fracture models were divided into 2 equal groups: an experimental group ( n=12) subjected to fixation with one SCB combined with bilateral LCPs with 10 locking screws and a control group ( n=12) subjected to fixation with bilateral LCPs with 12 locking screws. In each model, a vertical ballast test was conducted to record the maximum axial displacement of the system and a horizontal torsion test to calculate the torsional stiffness of the system. When the loading pressure was 0-1,000 N in the biomechanical machine, structural abnormalities were observed in the 2 groups of models and the system maximum axial displacement and system torsional stiffness were compared between the 2 groups. Results:When the vertical ballast pressure was 400 N, 600 N, 800 N and 1,000 N, the maximum axial displacement of the system was, respectively, (0.14±0.01) mm, (0.25±0.01) mm, (0.41±0.02) mm and (0.63 ± 0.02) mm in the experimental group, and (0.15 ± 0.01) mm, (0.26 ± 0.01) mm, (0.46 ± 0.03) mm, and (0.67 ± 0.04) mm in the control group. Compared with the control group, the average maximum axial displacement in the experimental group decreased significantly under the axial pressure of 600-1,000 N ( P<0.05). When the horizontal torsion reached 5°, the torsional stiffness was, respectively, (2.00±0.12) Nm/° and (2.02±0.07) Nm/° in the experimental group and the control group, showing no significant difference between the 2 groups ( P>0.05). Conclusions:In the treatment of intra-articular distal femur fracture, compared with simple bilateral LCPs, our SCB combined with bilateral LCPs demonstrate similar torsional stability but better axial biomechanical stability. As our SCB has advantages of bilateral compression and minimal invasion in operation, it may be a new option for the reduction and compression treatment of intra-articular fractures.

Objective:To summarize the clinical characteristics and prognosis of acute hyperextension spinal cord injury (SCI) in children, and to provide some recommendations for the treatment and prevention of this disease.Methods:Reviewed the data of children of SCI after sustained or repeated hyperextension of the spine at Wuhan Union Hospital and Wuhan Children's Hospital from September 2010 to September 2020. According to the American Spinal Injury Association impairment scale (AIS grade), the patients were divided into complete SCI group and incomplete SCI group. The age, symptoms and evolution after injury, neurological level of injury, imaging data, laboratory examination data, prognosis and complications of the two groups were analyzed. Retrospectively summarize the characteristics of this type of injury.Results:Forty-four cases of acute hyperextension SCI in children were included. Their age ranged from 3 to 10 years old, 95% of them were under 8 years old and 95% of them were female. There was no significant difference in age at injury and time of dance training between children with complete SCI and incomplete SCI. Back and leg pain, lower limb weakness or paresthesia, and rapidly progress to complete or incomplete SCI in a short period were typical symptoms. All blood test results anddiagnostic analysis of cerebrospinal fluid were unremarkable or negative. There was no fracture or dislocation in the whole spine. Magnetic resonance imaging showed a longitudinally extended intramedullary high-intensity signal in the thoracolumbar spinal cord. Complete SCI accounted for 60% of all cases, and the prognosis was poor with spinal cord atrophy and various complications.Conclusion:Children younger than 10 years old after sustained or repeated hyperextension of the spine may suffer acute hyperextension SCI. Children with complete SCI have poor prognosis and serious complications. Therefore, prevention of this type of injury is the best strategy.

Objective:To explore the safety and efficacy of the minimally invasive treatment of unstable pelvic fractures with the blunt head technique of Kirschner wire and 3D-printed external template technique.Methods:A retrospective study was conducted of the clinical data of 21 patients with unstable pelvic fracture who had undergone minimally invasive treatment at Department of Orthopaedics, Union Hospital from May 2016 to July 2018 using 3D-printed external templates and the blunt head technique of Kirschner wire. There were 7 males and 14 females with an age of 43.6 years (from 19 to 65 years). According to the Tile classification, there were 3 cases of B1, 7 ones of B2, 6 ones of C1 and 5 ones of C2. The intraoperative fluoroscopy, operation time, postoperative fracture reduction and functional recovery of the pelvis at the last follow-up were recorded.Results:The 21 patients were followed up for an average of 16.3 months (from 12 to 24 months). A total of 33 wires were inserted in the 21 patients, including 15 S 1 ones and 18 S 2 ones. The intraoperative fluoroscopy ranged from 13 to 27 times, averaging 21.8 times. The operation time ranged from 65 to 130 min, averaging 88.6 min. The anterior subcutaneous internal fixation was used to fix the anterior ring in 9 patients. No vascular injury occurred during the operation. By the Matta criteria, the postoperative fracture reduction was assessed as excellent in 14 cases, good in 5, and fair in 2, giving an excellent to good rate of 90.5% (19/21). By the Majeed scoring system, the pelvic function at the last follow-up was assessed as excellent in 10 cases, good in 8, and fair in 3, giving an excellent to good rate of 85.7% (18/21). Lateral femoral cutaneous nerve injury occurred in 2 patients but was recovered by the 3-month follow-up. No other complications were follwed up. Conclusion:The minimally invasive treatment of unstable pelvic fractures with the blunt head technique of Kirschner wire assissted by 3D-printed external templates is safe and effective, showing advatages of reduced fluoroscopic frequency and operation time.

Objective:To investigate the associations of articular depression depth (ADD) and tibial plateau widening (TPW) by pre-operative CT measurement with incidence of lateral meniscal tear in patients with Schatzker type Ⅱ tibial plateau fracture.Methods:Included in this retrospective study were 131 patients who had been admitted to Emergency Center of Trauma, The Third Hospital Affiliated to Hebei Medical University from January 2016 to January 2020 for Schatzker type Ⅱtibial plateau fractures. They were 88 males and 51 females, aged from 18 to 60 years (average, 41.5 years), with 74 right and 57 left sides injured. All patients were treated with closed reduction and internal fixation assisted by bidirectional traction. Arthroscopy was used to detect the status of lateral meniscus immediately after closed reduction and internal fixation of the fracture fragments. Furthermore, patients were divided into 2 groups according to the integrity of lateral meniscus: meniscal tear group ( n=70) and tear-free group ( n=61). The 2 groups were compared in terms of age, gender, body mass index(BMI), injury side, time interval from injury to surgery, TPW and ADD. The receiver operating curve (ROC) was drafted to calculate the cut-off values of TPW and ADD in complication of lateral meniscal tear in patients with Schatzker type Ⅱ tibial plateau fracture. Results:The overall incidence of lateral meniscal tear in this cohort was 53.4% (70/131). There was no statistically significant difference in terms of age, gender, injury side, BMI or time interval from injury to surgery between the 2 groups ( P>0.05); TPW and ADD were significantly higher in the meniscal tear group than in the tear-free group ( P<0.05). To predict lateral meniscal tear in patients with Schatzker type Ⅱtibial plateau fracture, the area under ROC was 0.656 (95% CI: 0.562 to 0.750, P=0.002) for TPW and 0.709 (95% CI: 0.619 to 0.800, P<0.001) for ADD, respectively; the cut-off values of TPW and ADD were 4.3 mm and 6.1 mm. Conclusion:TPW and ADD may be effective predictors for prediction of lateral meniscal tear in patients with Schatzker type Ⅱ tibial plateau fracture.

Objective:To evaluate our self-designed easily-breaking compression bone bolt plus bone plate in the treatment of tibial plateau fracture.Methods:From July 2018 to December 2018, 12 patients with tibial plateau fracture were treated at Emergency Center of Trauma, The Third Hospital of Hebei Medical University using our self-designed easily-breaking compression bone bolt plus bone plate. They were 8 males and 4 females, aged from 20 to 65 years (average, 45.6 years), with 6 left sides and 6 right sides injured. According to Schatzker classification, there were one case of type I, 3 cases of type Ⅱ, 3 cases of type Ⅲ, 2 cases of type Ⅳ, one case of type Ⅴ and 2 cases of type Ⅵ. The width of tibial plateau was measured and compared before and after operation on X-ray films. Operation time, blood loss and fracture union time were recorded. Loss of reduction and postoperative complications were followed up. Knee function was evaluated at the final follow-up by Rasmussen scoring.Results:For this cohort, operation time averaged 54.6 min, blood loss 25 mL, and fracture union time 17.2 weeks. No nonunion or delayed union was observed. The postoperative width of tibial plateau was (78.9±7.2) mm, significantly narrower than the preoperative value [(87.4±6.1) mm] ( P < 0.05). No loss of reduction or surgical complications occurred postoperation. Deep venous thrombosis of the lower extremity developed in 2 patients but recovered after treatment. The Rasmussen scoring for knee joint function at the final follow-up yielded 9 excellent, 2 good and one poor. Conclusion:In treatment of tibial plateau fractures, our self-designed easily-breaking compression bone bolt plus bone plate can restore width of tibial plateau, compress fracture fragments tightly and allow for early exercise, leading to fine functional recovery of the knee joint.