Shenhu area in South China Sea includes extensive collapse and diapir structures,forming high-angle faults and vertical fracture system,which functions as a fluid migration channel for gas hydrate formation.In order t...Shenhu area in South China Sea includes extensive collapse and diapir structures,forming high-angle faults and vertical fracture system,which functions as a fluid migration channel for gas hydrate formation.In order to improve the imaging precision of natural gas hydrate in this area,especially for fault and fracture structures,the present work propose a velocity stitching technique that accelerates effectively the convergence of the shallow seafloor,indicating seafloor horizon interpretation and the initial interval velocity for model building.In the depth domain,pre-stack depth migration and residual curvature are built into the model based on high-precision grid-tomography velocity inversion,after several rounds of tomographic iterations,as the residual velocity field converges gradually.Test results of the Shenhu area show that the imaging precision of the fault zone is obviously improved,the fracture structures appear more clearly,the wave group characteristics significantly change for the better and the signal-to-noise ratio and resolution are improved.These improvements provide the necessary basis for the new reservoir model and field drilling risk tips,help optimize the favorable drilling target,and are crucial for the natural gas resource potential evaluation.展开更多
BACKGROUND Periprosthetic joint infection(PJI) and periprosthetic fracture(PPF) are among the most serious complications following total knee arthroplasty. Herein, we present one patient with these two complications w...BACKGROUND Periprosthetic joint infection(PJI) and periprosthetic fracture(PPF) are among the most serious complications following total knee arthroplasty. Herein, we present one patient with these two complications with details on the characteristics, treatment strategy, and outcome.CASE SUMMARY A 69-year-old female patient who suffered from PJI and PPF following total knee arthroplasty was treated by a two-stage revision surgery. After thorough foreign material removal and debridement, we used a plate that was covered with antibiotic-loaded bone cement to link with a hand-made cement spacer to occupy the joint space and fix the fracture. Although the infection was cured, the fracture did not heal and caused bone defect due to the long interval between debridement and revision. In the revision surgery, a cemented stem and cortical allogenic splints were used to reconstruct the fracture and bone defect. At the final followup 27 mo after revision, the patient was satisfied with postoperative knee functions with satisfactory range of motion(104°) and Hospital for Special Surgery knee score(82 points). The radiographs showed no loosening of the prosthesis and that the bone grafts healed well with the femur.CONCLUSION Our two-stage revision surgery has proved to be successful and may be considered in other patients with PJI and PPF.展开更多
Background： Lateral compartmental osteoarthritis （LCOA）, a major complication after medial mobile-bearing unicompartmental knee arthroplasty （UKA）, is highly associated with the increased stress of the lateral co...Background： Lateral compartmental osteoarthritis （LCOA）, a major complication after medial mobile-bearing unicompartmental knee arthroplasty （UKA）, is highly associated with the increased stress of the lateral compartment. This study aimed to analyze the effects on the stress and load distribution of the lateral compartment induced by lower limb alignment and coronal inclination of the tibial component in UKA through a finite element analysis. Methods： Eight three-dimensional models were constructed based on a validated model for analyzing the biomechanical effects of implantation parameters on the lateral compartment after medial Oxford UKA： postoperative lower limb alignment of 3° valgus, neutral and 3° varus, and the inclination of tibial components placed in 4°, 2° valgus, square, and 2° and 4° varus. The contact stress of femoral and tibial cartilage and load distribution were calculated for all models. Results： In the 3° valgus lower limb alignment model, the contact stress of femoral （3.38 MPa） and tibial （3.50 MPa） cartilage as well as load percentage （45.78%） was highest compared to any other model, and was increased by 36.75%, 47.70%, and 27.63%, respectively when compared to 3° varus. In the condition of a neutral position, the outcome was comparable for the different tibial tray inclination models. The inclination did not greatly affect the lateral compartmental stress and load distribution. Conclusions： This study suggested that slightly varus （undercorrection） lower limb alignment might be a way to prevent LCOAin medial mobile-bearing UKA. However, the inclination （4° varus to 4° valgus） of the tibial component in the coronal plane would not be a risk factor for LCOA in neutral position.展开更多
Background： The lateral pillar of the femoral head is an important site for disease development such as osteonecrosis of the femoral head. The femoral head consists of medial, central, and lateral pillars. This study...Background： The lateral pillar of the femoral head is an important site for disease development such as osteonecrosis of the femoral head. The femoral head consists of medial, central, and lateral pillars. This study aimed to determine the biomechanical effects of early osteonecrosis in pillars of the femoral head via a finite element （FE） analysis. Methods： A three-dimensional FE model of the intact hip joint was constructed from the image data of a healthy control. Further, a set of six early osteonecrosis models was developed based on the three-pillar classification. The von Mises stress and surface displacements were calculated for all models. Results： The peak values of von Mises stress in the cortical and cancellous bones of normal model were 6.41 MPa and 0.49 MPa, respectively. In models with necrotic lesions in the cortical and cancellous bones, the von Mises stress and displacement of lateral pillar showed significant variability： the stress of cortical bone decreased from 6.41 MPa to 1.51 MPa （76.0% reduction）, while cancellous bone showed an increase from 0.49 MPa to 1.28 MPa （159.0% increase）; surface displacements of cortical and cancellous bones increased from 52.4 μm and 52.1 μm to 67.9 μm （29.5%） and 61.9 μm （18.8%）, respectively. In addition, osteonecrosis affected not only pillars but also adjacent structures in terms of the von Mises stress and surface displacement levels. Conclusions： This study suggested that the early-stage necrosis in the femoral head could increase the risk of collapse, especially in lateral pillar. On the other hand, the cortical part of lateral pillar was found to be the main biomechanical support of femoral head.展开更多
基金This study was financially supported by the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0207)Dedicated Fund for Promoting High-Quality Economic Development in Guangdong Province(Marine Economic Development Project)(GDNRC[2020]045)the State Key Laboratory of Marine Geology of Tongji University(MGK202007).
文摘Shenhu area in South China Sea includes extensive collapse and diapir structures,forming high-angle faults and vertical fracture system,which functions as a fluid migration channel for gas hydrate formation.In order to improve the imaging precision of natural gas hydrate in this area,especially for fault and fracture structures,the present work propose a velocity stitching technique that accelerates effectively the convergence of the shallow seafloor,indicating seafloor horizon interpretation and the initial interval velocity for model building.In the depth domain,pre-stack depth migration and residual curvature are built into the model based on high-precision grid-tomography velocity inversion,after several rounds of tomographic iterations,as the residual velocity field converges gradually.Test results of the Shenhu area show that the imaging precision of the fault zone is obviously improved,the fracture structures appear more clearly,the wave group characteristics significantly change for the better and the signal-to-noise ratio and resolution are improved.These improvements provide the necessary basis for the new reservoir model and field drilling risk tips,help optimize the favorable drilling target,and are crucial for the natural gas resource potential evaluation.
基金Supported by the General Cultivation Project of Xi'an Health Commission,No.2021ms08.
文摘BACKGROUND Periprosthetic joint infection(PJI) and periprosthetic fracture(PPF) are among the most serious complications following total knee arthroplasty. Herein, we present one patient with these two complications with details on the characteristics, treatment strategy, and outcome.CASE SUMMARY A 69-year-old female patient who suffered from PJI and PPF following total knee arthroplasty was treated by a two-stage revision surgery. After thorough foreign material removal and debridement, we used a plate that was covered with antibiotic-loaded bone cement to link with a hand-made cement spacer to occupy the joint space and fix the fracture. Although the infection was cured, the fracture did not heal and caused bone defect due to the long interval between debridement and revision. In the revision surgery, a cemented stem and cortical allogenic splints were used to reconstruct the fracture and bone defect. At the final followup 27 mo after revision, the patient was satisfied with postoperative knee functions with satisfactory range of motion(104°) and Hospital for Special Surgery knee score(82 points). The radiographs showed no loosening of the prosthesis and that the bone grafts healed well with the femur.CONCLUSION Our two-stage revision surgery has proved to be successful and may be considered in other patients with PJI and PPF.
基金This study was supported by grants from the National Natural Science Foundation of China(No.81673776)the capital health research and development of special,China(No.2016-2-4062).
文摘Background： Lateral compartmental osteoarthritis （LCOA）, a major complication after medial mobile-bearing unicompartmental knee arthroplasty （UKA）, is highly associated with the increased stress of the lateral compartment. This study aimed to analyze the effects on the stress and load distribution of the lateral compartment induced by lower limb alignment and coronal inclination of the tibial component in UKA through a finite element analysis. Methods： Eight three-dimensional models were constructed based on a validated model for analyzing the biomechanical effects of implantation parameters on the lateral compartment after medial Oxford UKA： postoperative lower limb alignment of 3° valgus, neutral and 3° varus, and the inclination of tibial components placed in 4°, 2° valgus, square, and 2° and 4° varus. The contact stress of femoral and tibial cartilage and load distribution were calculated for all models. Results： In the 3° valgus lower limb alignment model, the contact stress of femoral （3.38 MPa） and tibial （3.50 MPa） cartilage as well as load percentage （45.78%） was highest compared to any other model, and was increased by 36.75%, 47.70%, and 27.63%, respectively when compared to 3° varus. In the condition of a neutral position, the outcome was comparable for the different tibial tray inclination models. The inclination did not greatly affect the lateral compartmental stress and load distribution. Conclusions： This study suggested that slightly varus （undercorrection） lower limb alignment might be a way to prevent LCOAin medial mobile-bearing UKA. However, the inclination （4° varus to 4° valgus） of the tibial component in the coronal plane would not be a risk factor for LCOA in neutral position.
基金This study was supported by grants from the National Natural Science Foundation of China(No.81673776)the Capital Health Research and Development of Special(No.2016-2-4062).
文摘Background： The lateral pillar of the femoral head is an important site for disease development such as osteonecrosis of the femoral head. The femoral head consists of medial, central, and lateral pillars. This study aimed to determine the biomechanical effects of early osteonecrosis in pillars of the femoral head via a finite element （FE） analysis. Methods： A three-dimensional FE model of the intact hip joint was constructed from the image data of a healthy control. Further, a set of six early osteonecrosis models was developed based on the three-pillar classification. The von Mises stress and surface displacements were calculated for all models. Results： The peak values of von Mises stress in the cortical and cancellous bones of normal model were 6.41 MPa and 0.49 MPa, respectively. In models with necrotic lesions in the cortical and cancellous bones, the von Mises stress and displacement of lateral pillar showed significant variability： the stress of cortical bone decreased from 6.41 MPa to 1.51 MPa （76.0% reduction）, while cancellous bone showed an increase from 0.49 MPa to 1.28 MPa （159.0% increase）; surface displacements of cortical and cancellous bones increased from 52.4 μm and 52.1 μm to 67.9 μm （29.5%） and 61.9 μm （18.8%）, respectively. In addition, osteonecrosis affected not only pillars but also adjacent structures in terms of the von Mises stress and surface displacement levels. Conclusions： This study suggested that the early-stage necrosis in the femoral head could increase the risk of collapse, especially in lateral pillar. On the other hand, the cortical part of lateral pillar was found to be the main biomechanical support of femoral head.
