The failure of bone injury repair surgery is mostly due to the stress shielding effect caused by the difference of elastic modulus between the implant prosthesis and human bone,result-ing in a great damage to patients...The failure of bone injury repair surgery is mostly due to the stress shielding effect caused by the difference of elastic modulus between the implant prosthesis and human bone,result-ing in a great damage to patients.To solve this problem,in this study,the influencing factors of the elastic modulus of implant prosthesis were investigated,the relationship between the elastic modulus of the implanted prosthesis and the influencing factors was analyzed,and then a design method of the implant prosthesis to reduce the stress shielding effect by adjusting the unit module to control the elastic modulus was established.This method was used for the biomechanical simula-tion to simulate the displacement and stress distribution between the implant prosthesis and the surrounding bone tissue,and then the reliability of the method was verified.The implant prosthe-sis with an elastic modulus consistent with that of the experimental dog bone was made by this method,and used for the animal experiments.The effects of implant prosthesis with different mod-ulus on the growth of surrounding bone tissue were observed,and at the same time,the reliability of the implant design method and the results of biomechanical simulation were verified.It is con-firmed that this method can effectively reduce the stress concentration of implant prosthesis by more than 15.4%and increase the growth of bone tissue by more than 21%.展开更多
The critical rainfall of runoff-initiated debris flows is utmost importance for local early hazard forecasting.This paper presents research on the critical rainfall of runoff-initiated debris flows through comparisons...The critical rainfall of runoff-initiated debris flows is utmost importance for local early hazard forecasting.This paper presents research on the critical rainfall of runoff-initiated debris flows through comparisons between slope gradients and three key factors,including topographic contributing area,dimensionless discharge,and Shields stress.The rainfall amount was estimated by utilizing in-situ rainfall records and a slope-dependent Shields stress model was created.The created model can predict critical Shields stress more accurately than the other two models.Furthermore,a new dimensionless discharge equation was proposed based on the corresponding discharge-gradient datasets.The new equation,along with factors such as contributing area above bed failure sites,channel width,and mean diameter of debris flow deposits,predicts a smaller rainfall amount than the in-situ measured records.Although the slope-dependent Shields stress model performs well and the estimated rainfall amount is lower than the in-situ records,the sediment initiation in the experiments falls within sheet flow regime due to a large Shields stress.Therefore,further sediment initiation experiments at a steeper slope range are expected in the future to ensure that the sediment transport belongs to mass failure regime characterized by a low level of Shields stress.Finally,a more accurate hazard forecast on the runoff-initiated debris flow holds promise when the corresponding critical slope-dependent dimensionless discharge of no motion,fluvial sediment transport,mass flow regime,and sheet flow regime are considered.展开更多
BACKGROUND Aseptic acetabular loosening can result from various factors that can be categorized into groups:patient-related,surgeon-related and implant-related.We present a case of a 63-year-old patient who at first u...BACKGROUND Aseptic acetabular loosening can result from various factors that can be categorized into groups:patient-related,surgeon-related and implant-related.We present a case of a 63-year-old patient who at first underwent a total hip arthro-plasty(THA)using a metal-on-metal bearing due to hip arthrosis.Follow-up visits revealed no complications after the procedure.Two years after the THA,acetabular component loosening occurred due to subsequent trauma of the opposite hip,necessitating a revision THA using a ceramic-on-ceramic bearing.CASE SUMMARY We aim to illustrate a rare case where the primary reason for undergoing THA revision was not only incomplete bone graft incorporation but also improper limb load distribution.Following the revision arthroplasty,a 9-year follow-up visit revealed improvements in all evaluation measures on questionnaire compared to the state before surgery:Harris Hip Score(before surgery:15;after surgery:95),Western Ontario and McMaster Universities Arthritis Index(before surgery:96;after surgery:0),and Visual Analogue Scale(before surgery:10;after surgery:1).CONCLUSION Opposite-hip trauma caused a weight transfer to the limb after a THA procedure.This process led to a stress shielding effect,resulting in acetabular component loosening.展开更多
基金supported by the 13th Five-Year Plan Science and Technology Research Project of Jilin Province Department of Education(JJKH20200066KJ)the Jilin Province Science and Technology Department Project(20200708126YY).
文摘The failure of bone injury repair surgery is mostly due to the stress shielding effect caused by the difference of elastic modulus between the implant prosthesis and human bone,result-ing in a great damage to patients.To solve this problem,in this study,the influencing factors of the elastic modulus of implant prosthesis were investigated,the relationship between the elastic modulus of the implanted prosthesis and the influencing factors was analyzed,and then a design method of the implant prosthesis to reduce the stress shielding effect by adjusting the unit module to control the elastic modulus was established.This method was used for the biomechanical simula-tion to simulate the displacement and stress distribution between the implant prosthesis and the surrounding bone tissue,and then the reliability of the method was verified.The implant prosthe-sis with an elastic modulus consistent with that of the experimental dog bone was made by this method,and used for the animal experiments.The effects of implant prosthesis with different mod-ulus on the growth of surrounding bone tissue were observed,and at the same time,the reliability of the implant design method and the results of biomechanical simulation were verified.It is con-firmed that this method can effectively reduce the stress concentration of implant prosthesis by more than 15.4%and increase the growth of bone tissue by more than 21%.
基金supported by the by the Second Tibetan Plateau Scientific Expedition and Research Program (Grant No. 2019QZKK0902)Beijing Municipal Science and Technology Project (Z191100001419015)
文摘The critical rainfall of runoff-initiated debris flows is utmost importance for local early hazard forecasting.This paper presents research on the critical rainfall of runoff-initiated debris flows through comparisons between slope gradients and three key factors,including topographic contributing area,dimensionless discharge,and Shields stress.The rainfall amount was estimated by utilizing in-situ rainfall records and a slope-dependent Shields stress model was created.The created model can predict critical Shields stress more accurately than the other two models.Furthermore,a new dimensionless discharge equation was proposed based on the corresponding discharge-gradient datasets.The new equation,along with factors such as contributing area above bed failure sites,channel width,and mean diameter of debris flow deposits,predicts a smaller rainfall amount than the in-situ measured records.Although the slope-dependent Shields stress model performs well and the estimated rainfall amount is lower than the in-situ records,the sediment initiation in the experiments falls within sheet flow regime due to a large Shields stress.Therefore,further sediment initiation experiments at a steeper slope range are expected in the future to ensure that the sediment transport belongs to mass failure regime characterized by a low level of Shields stress.Finally,a more accurate hazard forecast on the runoff-initiated debris flow holds promise when the corresponding critical slope-dependent dimensionless discharge of no motion,fluvial sediment transport,mass flow regime,and sheet flow regime are considered.
文摘BACKGROUND Aseptic acetabular loosening can result from various factors that can be categorized into groups:patient-related,surgeon-related and implant-related.We present a case of a 63-year-old patient who at first underwent a total hip arthro-plasty(THA)using a metal-on-metal bearing due to hip arthrosis.Follow-up visits revealed no complications after the procedure.Two years after the THA,acetabular component loosening occurred due to subsequent trauma of the opposite hip,necessitating a revision THA using a ceramic-on-ceramic bearing.CASE SUMMARY We aim to illustrate a rare case where the primary reason for undergoing THA revision was not only incomplete bone graft incorporation but also improper limb load distribution.Following the revision arthroplasty,a 9-year follow-up visit revealed improvements in all evaluation measures on questionnaire compared to the state before surgery:Harris Hip Score(before surgery:15;after surgery:95),Western Ontario and McMaster Universities Arthritis Index(before surgery:96;after surgery:0),and Visual Analogue Scale(before surgery:10;after surgery:1).CONCLUSION Opposite-hip trauma caused a weight transfer to the limb after a THA procedure.This process led to a stress shielding effect,resulting in acetabular component loosening.
