The basic stress pathway above the acetabular dome is important for the maintenance of implant stability in acetabular reconstruction of total hip arthroplasty (THA). The purpose of this study was to describe the basic stress pathway to provide evidence for clinical acetabular reconstruction guidance of THA. A subject-specific finite element (FE) model was developed from CT data to generate 3 normal hip models and a convergence study was conducted to determine the number of pelvic trabecular bone material properties using 5 material assignment plans. In addition, in the range of 0 to 20 mm above the acetabular dome, the models were sectioned and the stress pathway was defined as two parts, i.e., 3D, trabecular bone stress distribution and quantified cortical bone stress level. The results showed that using 100 materials to define the material property of pelvic trabecular bone could assure both the accuracy and efficiency of the FE model. Under the same body weight condition, the 3D trabecular bone stress distributions above the acetabular dome were consistent, and especially the quantified cortical bone stress levels were all above 20 MPa and showed no statistically significant difference (P>0.05). Therefore, defining the basic stress pathway above the acetabular dome under certain body weight condition contributes to design accurate preoperative plan for acetabular reconstruction, thus helping restore the normal hip biomechanics and preserve the stability of the implants.
Acetabulum ; anatomy & histology ; Arthroplasty, Replacement, Hip ; Biomechanical Phenomena ; Finite Element Analysis ; Hip Prosthesis ; Humans ; Imaging, Three-Dimensional ; Stress, Mechanical ; Tomography, X-Ray Computed

Objective:To investigate the status and influencing factors of application, project approval and scientific research output of innovation and entrepreneurship training program in medical undergraduates.Methods:A self-made questionnaire was used to investigate the application reasons, topic selection sources, project initiation, project type, implementation, progress, scientific research output and conclusion status of full-time medical undergraduates from Batch 2016 to 2020 in West China School of Medicine of Sichuan University. They were divided into two groups according to the situation whether they applied, whether they were approved and whether they had scientific research output. And the differences between the two groups were compared by chi-square test or t- test. Results:A total of 316 valid questionnaires were collected, of which 68.04% (215/316) applied for the innovation projects, 76.28% (164/215) obtained approval and 32.93% (54/164) had research output. The main reason that hindered students from applying for projects was the lack of guidance (70/101, 69.31%), and the main reason that prompted students to apply for projects was to increase the opportunities for postgraduate recommendation (147/215, 68.37%) and evaluation and award (151/215, 70.23%, 70.23%). 62.79% (135/215) of the project topics were inspired by tutor assignment, while independent topic selection was more conducive to project initiation (68/164, 41.46% vs. 12/51, 23.53%, P=0.021). Conclusion:The medical undergraduates have relatively high application and approval rate of innovation training program, but less scientific research output. Strengthening project application and topic selection guidance and process management can further improve the quality of innovation and entrepreneurship education for college students.

Objective To investigate biomechanical effects of different joint line height on unicompartmental knee arthroplasty (UKA) and to provide biomechanical evidence for surgical decision during UKA using finite element analysis (FEA).Methods On the basis of knee joint CT data from a healthy volunteer (male,30 years old,165 cm and 60 kg) and UKA prosthesis 3D scanned data,the 3D models of normal knee and UKA were constructed.Subject-specific finite element models with inhomogeneous material property assignment were constructed for normal knee and UKA with 3 different height of joint line (-3 mm,0 mm and +3 mm).Starting from the tibial articular surface,5 sections were extracted with 2 mm interval.30 nodes were selected in medial and lateral area,respectively on each section.The mean stress value of nodes was defined as the stress level of subchondral bone.Results Mean values of stress on polyethylene upper surface of 0,-3 and+3 mm joint line position were 14.84,26.81and 20.86 MPa,and the difference was statistical significant (t0vs-3=4.896,P0vs-3=0.000;t0vs+3=3.455,P0v+3=0.008;t-3vs+3=2.579,P-3vs+3=0.020).Mean values of stress on tibial prosthesis upper surface of 0,-3 and +3 mm joint line position were 29.69,50.49 and 39.99MPa,respectively,and the difference was statistical significant(t0vs-3=5.675,P0vs-3=0.000;t0vs+3=4.755,P0v+3=0.001;t-3vs+3=4.783,P-3vs+3=0.000).When joint line was in 0 mm height,stress level of subchondral bone was similar to that of normal knee.When joint line was in-3 mm height,significantly increased stress was found on polyethylene (increased 81％) and tibial component (increased 70％) surface compared with that of 0 mm height,while stress on trabecular bone under lateral tibial articular surface also increased by 8.7％.When joint line was in +3 mm height,increased stress on polyethylene (increased 41％) and tibial component (increased by 35％) surface were less than that of-3 mm height.Stress on trabecular bone under lateral articular surface decreased by 55.6％ compared with 0 mm height.Conclusion During UKA,ensuring a normal height of joint line is benefit to keep the stress path of the medial and lateral tibia similar with normal knee and decrease the risk of premature polyethylene wear,tibial component subsidence and periprosthetic fracture.