{"title":"Biomechanical comparison of fixation systems in posterior wall fracture of acetabular by finite element analysis","authors":"Jianyin Lei, Hai-bo Liu, Zhiqiang Li, Zhihua Wang, Ximing Liu, Longmao Zhao","doi":"10.1080/24699322.2016.1218052","DOIUrl":"https://doi.org/10.1080/24699322.2016.1218052","url":null,"abstract":"Abstract Background: The use of reconstruction plates and lag screws has been recommended for fractures to the posterior wall of the acetabulum. However, little information about the rigidity of recommended forms of fracture fixation is available. This study aimed to evaluate the biomechanical difference among the fixation systems. Methods: A posterior wall fracture, which is represented by softer elements with lower elastic modulus, was created along an arc of 40–90° about the acetabular rim. Three different fixation systems: screws alone, reconstruction plate with screws, reconstruction plate with T-shaped plates were used to fix the posterior wall fractures to the acetabulum. Results: All three fixation system can be used to obtain good functional outcomes. The reconstruction plate with T-shaped plates was beneficial to increasing the effective stiffness, decreasing the stress concentration and enhancing the rigidity of fracture fixation. So this fixation system served an ideal result in the analysis. Conclusion: Theoretically, the reconstruction plate with T-shaped plates system may reduce many of the risks and limitations compared to the other fixation systems. This fixation system may result in a clinical benefit.","PeriodicalId":56051,"journal":{"name":"Computer Assisted Surgery","volume":"21 1","pages":"117 - 126"},"PeriodicalIF":2.1,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/24699322.2016.1218052","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60126202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Accuracy of estimating Unicondylar Knee Replacement implant varus/valgus angles from antero-posterior radiographs","authors":"R. Khare, B. Jaramaz","doi":"10.1080/24699322.2016.1199736","DOIUrl":"https://doi.org/10.1080/24699322.2016.1199736","url":null,"abstract":"Abstract Unicondylar Knee Replacement (UKR) is an orthopedic surgical procedure to reduce pain and improve function in the knee. Load-bearing long-standing antero-posterior (AP) radiographs are typically used postoperatively to measure the leg alignment and assess the varus/valgus implant orientation. However, implant out-of-plane rotations, user variability, and X-ray acquisition parameters introduce errors in the estimation of the implant varus/valgus estimation. Previous work has explored the accuracy of various imaging modalities in this estimation. In this work, we explored the impact of out-of-plane rotations and X-ray acquisition parameters on the estimation of implant component varus/valgus angles. For our study, we used a single CT scan and positioned femoral and tibial implants under varying orientations within the CT volume. Then, a custom software application was used to obtain digitally reconstructed radiographs from the CT scan with implants under varying orientations. Two users were then asked to manually estimate the varus/valgus angles for the implants. We found that there was significant inter-user variability (p < 0.05) in the varus/valgus estimates for the two users. However, the ‘ideal’ measurements, obtained using actual implant orientations, showed small errors due to variations in implant orientation. We also found that variation in the projection center does not have a statistically significant impact (p < 0.01) on the estimation of implant varus/valgus angles. We conclude that manual estimates of UKR implant varus/valgus orientations are unreliable.","PeriodicalId":56051,"journal":{"name":"Computer Assisted Surgery","volume":"12 1","pages":"80 - 84"},"PeriodicalIF":2.1,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/24699322.2016.1199736","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60126072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}