OBJECTIVE: To investigate whether adding 1 transverse screw (TS) to the triangular parallel cannulated screw (TPCS) fixation has a mechanical stability advantage for Pauwels type Ⅲ femoral neck fractures by conducting finite element analysis on four internal fixation methods. METHODS: Based on CT data of a healthy adult male volunteer's femur, three Pauwels type Ⅲ femoral neck fracture models (Pauwels angle 70°, Pauwels angle 80°, and Pauwels angle 70° combined with bone defect) were constructed using Mimics 21.0 software and SolidWorks 2017 software. Four different internal fixation models were built at the same time, including TPCS, TPCS+TS, three cross screws (TCS), and TPCS+medial buttress plate (MBP). The mechanical stability of different models under the same load was compared by finite element analysis. RESULTS: The femoral model established in this study exhibited a maximum stress of 28.62 MPa, with relatively higher stress concentrated in the femoral neck. These findings were comparable to previous studies, indicating that the constructed femoral finite element model was correct. The maximum stress of internal fixation in finite element analysis showed that TCS was the lowest and TPCS+MBP was the highest in Pauwels angle 70° and 80° models, while TPCS+TS was the lowest and TCS was the highest in Pauwels angle 70° combined with bone defect model. The maximum displacement of internal fixation in each fracture model was located at the top of the femoral head, with TCS having the highest maximum displacement of the femur. The maximum stress of fracture surface in finite element analysis showed that TCS was the lowest and TPCS was the highest in the Pauwels angle 70° model, while TPCS+MBP was the lowest and TPCS/TCS were the highest in the Pauwels angle 80° model and the Pauwels angle 70° combined with bone defect model, respectively. The maximum displacement of fracture surfece analysis showed that TPCS+MBP was the lowest and TCS was the highest in Pauwels angle 70° and 80° models, while TPCS+TS was the lowest and TCS was the highest in Pauwels angle 70° combined with bone defect model. CONCLUSION For Pauwels type Ⅲ femoral neck fractures, the biomechanical stability of TPCS+TS was superior to that of TPCS alone and TCS, but it has not yet reached the level of TPCS+MBP.
Finite Element Analysis ; Humans ; Femoral Neck Fractures/diagnostic imaging* ; Bone Screws ; Fracture Fixation, Internal/instrumentation* ; Male ; Bone Plates ; Stress, Mechanical ; Biomechanical Phenomena ; Tomography, X-Ray Computed ; Adult ; Femur Neck/surgery*

Objective To study the effect of COVID-19 pandemic on the stroke center of Yongchuan Hospital Affiliated to Chongqing Medical University（“our hospital” for short），so as to provide reference for the stroke center to cope with COVID-19 pandemic.Methods 161 stroke patients in our hospital from January 24 to March 10，2020（the first level response period for major public health emergencies in Chongqing） were selected as the pandemic group. 259 stroke patients in our hospital from February 4 to March 23，2019（the same period in the lunar calendar with 2020）were selected as non pandemic group，and the clinical data of the two groups were compared.Results The time of visiting hospital and the ratio of ischemic stroke patients in pandemic group were lower than those in non pandemic group，and the emergency visiting rate，calling ambulance rate，hospitalization rate，hospitalization days，critical ill rate，special or primary nursing rate were higher than those in non pandemic group（P<0.05）；there was no statistical significance between the two groups in gender and age（P>0.05）.Between the emergency visiting patients of the two groups，There was no significant difference in the time of visiting hospital（P>0.05）.Between the ischemic stroke patients of the two groups，time from door to puncture in thrombectomy（DTP） in pandemic group was lower than that in non pandemic group（P<0.05），There was no significant difference in the National Institute of Health Stroke Scale（NIHSS score），thrombolysis rate，time from door-to-needle in thrombolysis（DNT），and Endovascular therapy rate（P>0.05）.Between the Hemorrhagic stroke patients of the two groups，The emergency operation rate in pandemic group was higher than that in the non pandemic group，and the time from admission to emergency operation in pandemic was shorter than that in the non pandemic group.Conclusion During the period of COVID-19 pandemic，the patients in the stroke center showed the following characteristics compared with normal：the number of visiting hospital was reduced，the time of visiting hospital was shortened，the degree of illness was aggravated，the hospitalization rate was increased，the hospitalization days were increased，the ischemic stroke ratio was reduced，the DTP of ischemic stroke was shortened，the emergency operation rate of hemorrhagic stroke was increased，and the time from admission to emergency operation of hemorrhagic stroke was shortened.