ASTM F75 is a low-carbon CoCrMo alloy which has been used as hip implant material for decades,but the ASTM F75 implants can fail when the femoral head and the acetabular cup loosen because of limited metal-on-metal be...ASTM F75 is a low-carbon CoCrMo alloy which has been used as hip implant material for decades,but the ASTM F75 implants can fail when the femoral head and the acetabular cup loosen because of limited metal-on-metal bearing.Therefore,a modified version of ASTM F75 alloy which has 90 wt.%ASTM F75 plus 10 wt.%Cr is proposed.The wear and corrosion resistance of both alloys are investigated simulating the working environment of hip implants in human body.The mechanics behavior of the femoral implant under the loading condition in human body with ASTM F75 or modified ASTM F75 material used is studied with FEA simulation.The cytotoxicity(MTT)assays of the alloys are measured and compared to that of inert ceramic and cytotoxic cobalt.The experimental and simulation results show that the proposed alloy exhibits better wear and corrosion resistance than the conventional hip implant material.Both alloys behave well with respect to stress and deformation when used for the femoral implant under the loading condition in human body.These two alloys display similar cytotoxicity performance to inert ceramic.展开更多
AIM To determine whether cemented, cementless, or hybrid implant was superior to the other in terms of survival rate.METHODS Systematic searches across MEDLINE, CINAHL, and Cochrane that compared cemented, cementless ...AIM To determine whether cemented, cementless, or hybrid implant was superior to the other in terms of survival rate.METHODS Systematic searches across MEDLINE, CINAHL, and Cochrane that compared cemented, cementless and hybrid total hip replacement(THR) were performed. Two independent reviewers evaluated the risk ratios of revision due to any cause, aseptic loosening, infection, and dislocation rate of each implants with a pre-determined form. The risk ratios were pooled separately for clinical trials, cohorts and registers before pooled altogether using fixed-effect model. Meta-regressions were performed to identify the source of heterogeneity. Funnel plots were analyzed. RESULTS Twenty-seven studies comprising 5 clinical trials, 9 cohorts, and 13 registers fulfilled the research criteria and analyzed. Compared to cementless THR, cemented THR have pooled RR of 0.47(95%CI: 0.45-0.48), 0.9(0.84-0.95), 1.29(1.06-1.57) and 0.69(0.6-0.79) for revision due to any reason, revision due to aseptic loosening, revision due to infection, and dislocation respectively. Compared to hybrid THR, the pooled RRs of cemented THR were 0.82(0.76-0.89), 2.65(1.14-6.17), 0.98(0.7-1.38), and 0.67(0.57-0.79) respectively. Compared to hybrid THR, cementless THR had RRs of 0.7(0.65-0.75), 0.85(0.49-1.5), 1.47(0.93-2.34) and 1.13(0.98-1.3).CONCLUSION Despite the limitations in this study, there was some tendency that cemented fixation was still superior than other types of fixation in terms of implant survival.展开更多
Periprosthetic joint infections(PJI) of the hip and the knee are grossly classified as early post-operative, acute hematogenous and late chronic infections. Whereas two-stage exchange arthroplasty is the standard of c...Periprosthetic joint infections(PJI) of the hip and the knee are grossly classified as early post-operative, acute hematogenous and late chronic infections. Whereas two-stage exchange arthroplasty is the standard of care in North America for treating chronic infections, irrigation and debridement(I and D) with retention of implants has been used in an attempt to treat the other two types of PJIs. The rationale of this approach is that a PJI may be eradicated without the need of explanting the prostheses, as long as it has not transitioned into a chronic state. With the present paper, we review current evidence regarding the role of I and D with implant retention for treating PJIs of the hip and the knee. While a very wide range of success rates is reported in different studies, a short period of time between initiation of symptoms and intervention seems to play a prominent role with regards to a successful outcome. Moreover, pathogens of higher virulence and resistance to antibiotics are associated with a poorer result. Specific comorbidities have been also correlated with a less favorable outcome. Finally, one should proceed with serial I and Ds only under the condition that a predefined,aggressive protocol is applied. In conclusion,when treating a PJI of the hip or the knee, all the above factors should be considered in order to decide whether the patient is likely to benefit from this approach.展开更多
Wear is an important issue in hip implants. Excessive wear can lead to toxicity and other implant associated medical issues such as patient discomfort and decreased mobility. Since implant wear is the result of contac...Wear is an important issue in hip implants. Excessive wear can lead to toxicity and other implant associated medical issues such as patient discomfort and decreased mobility. Since implant wear is the result of contact between surfaces of femoral head and acetabulum implant, it is important to establish a model that can address implant surface roughness interaction. A statistical contact model is developed for the interaction of femoral head and acetabulum implant in which surface roughness effects are included. The model accounts for the elastic-plastic interaction of the implant surface roughness. For this purpose femoral head and acetabulum implants are considered as macroscopically spherical surfaces containing micron-scale roughness. Approximate equations are obtained that relate the contact force to the mean surface separation explicitly. Closed form equations are obtained for hysteretic energy loss in implant using the approximate equations.展开更多
To study the influence of head-neck ratio and implant position on the range of motion (ROM) after total hip arthroplasty (THA).Methods In this study the author established a three-dimensional computerized model of hip...To study the influence of head-neck ratio and implant position on the range of motion (ROM) after total hip arthroplasty (THA).Methods In this study the author established a three-dimensional computerized model of hip joint and tested the range of motion of three different head-neck ratio after total hip arthroplasty.Results Range of motion after total hip arthroplasty depended on design parameters such as head-neck ratio,but also on the implantation parameters such as the cup’s inclination and antevertion,the stem’s antevertion and their combination of each other.Optimal range of motion required compliant position of total hip components.The range of motion increased with the enlarging of head-hnck ratio.Conclusion Higher head-neck ratio leads to optimal range of motion and decreased the prevalence of prosthetic impingement within compliant,well-defined combination of cup’s inclination,cup’s antevertion and stem’s antevertion depending on the intended ROM.Domestic magnesium-silicon jade total hip prosthesis has too low head-neck ratio to result in enough range of motion that fulfilled daily living after total hip arthroplasty.14 refs,4 figs,3 tabs.展开更多
This paper presents a probabilistic approach for studying the reliability of cementless hip prostheses in the presence of mechanical uncertainties and its application to the investigation of the influence of bone-impl...This paper presents a probabilistic approach for studying the reliability of cementless hip prostheses in the presence of mechanical uncertainties and its application to the investigation of the influence of bone-implant interface properties. The non-linear deterministic model of the bone-implant coupled system and its finite element implementation are described, and the proposed reliability analysis is exposed. It is demonstrated that the distribution (uniform, truncated Gaussian and truncated lognormal distribution) of the two chosen parameters and the truncation lengths have a minor influence on the Hasofer-Lind index. This index logically increases as the failure threshold increases. FORM and SORM approximations are compared with the results obtained using a crude Monte-Carlo method for the estimation of failure probability. The performance of three Monte-Carlo methods is studied in terms of the necessary number of FE calculations. The method based on the Directional Simulation (DS) technique is efficient and less time-consuming. The validity and operational capacity of the proposed approach would not be compromised by an increase in the number of uncertain parameters.展开更多
基金The authors are grateful for financial support from Natural Science&Engineering Research Council of Canada(NSERC).
文摘ASTM F75 is a low-carbon CoCrMo alloy which has been used as hip implant material for decades,but the ASTM F75 implants can fail when the femoral head and the acetabular cup loosen because of limited metal-on-metal bearing.Therefore,a modified version of ASTM F75 alloy which has 90 wt.%ASTM F75 plus 10 wt.%Cr is proposed.The wear and corrosion resistance of both alloys are investigated simulating the working environment of hip implants in human body.The mechanics behavior of the femoral implant under the loading condition in human body with ASTM F75 or modified ASTM F75 material used is studied with FEA simulation.The cytotoxicity(MTT)assays of the alloys are measured and compared to that of inert ceramic and cytotoxic cobalt.The experimental and simulation results show that the proposed alloy exhibits better wear and corrosion resistance than the conventional hip implant material.Both alloys behave well with respect to stress and deformation when used for the femoral implant under the loading condition in human body.These two alloys display similar cytotoxicity performance to inert ceramic.
文摘AIM To determine whether cemented, cementless, or hybrid implant was superior to the other in terms of survival rate.METHODS Systematic searches across MEDLINE, CINAHL, and Cochrane that compared cemented, cementless and hybrid total hip replacement(THR) were performed. Two independent reviewers evaluated the risk ratios of revision due to any cause, aseptic loosening, infection, and dislocation rate of each implants with a pre-determined form. The risk ratios were pooled separately for clinical trials, cohorts and registers before pooled altogether using fixed-effect model. Meta-regressions were performed to identify the source of heterogeneity. Funnel plots were analyzed. RESULTS Twenty-seven studies comprising 5 clinical trials, 9 cohorts, and 13 registers fulfilled the research criteria and analyzed. Compared to cementless THR, cemented THR have pooled RR of 0.47(95%CI: 0.45-0.48), 0.9(0.84-0.95), 1.29(1.06-1.57) and 0.69(0.6-0.79) for revision due to any reason, revision due to aseptic loosening, revision due to infection, and dislocation respectively. Compared to hybrid THR, the pooled RRs of cemented THR were 0.82(0.76-0.89), 2.65(1.14-6.17), 0.98(0.7-1.38), and 0.67(0.57-0.79) respectively. Compared to hybrid THR, cementless THR had RRs of 0.7(0.65-0.75), 0.85(0.49-1.5), 1.47(0.93-2.34) and 1.13(0.98-1.3).CONCLUSION Despite the limitations in this study, there was some tendency that cemented fixation was still superior than other types of fixation in terms of implant survival.
文摘Periprosthetic joint infections(PJI) of the hip and the knee are grossly classified as early post-operative, acute hematogenous and late chronic infections. Whereas two-stage exchange arthroplasty is the standard of care in North America for treating chronic infections, irrigation and debridement(I and D) with retention of implants has been used in an attempt to treat the other two types of PJIs. The rationale of this approach is that a PJI may be eradicated without the need of explanting the prostheses, as long as it has not transitioned into a chronic state. With the present paper, we review current evidence regarding the role of I and D with implant retention for treating PJIs of the hip and the knee. While a very wide range of success rates is reported in different studies, a short period of time between initiation of symptoms and intervention seems to play a prominent role with regards to a successful outcome. Moreover, pathogens of higher virulence and resistance to antibiotics are associated with a poorer result. Specific comorbidities have been also correlated with a less favorable outcome. Finally, one should proceed with serial I and Ds only under the condition that a predefined,aggressive protocol is applied. In conclusion,when treating a PJI of the hip or the knee, all the above factors should be considered in order to decide whether the patient is likely to benefit from this approach.
文摘Wear is an important issue in hip implants. Excessive wear can lead to toxicity and other implant associated medical issues such as patient discomfort and decreased mobility. Since implant wear is the result of contact between surfaces of femoral head and acetabulum implant, it is important to establish a model that can address implant surface roughness interaction. A statistical contact model is developed for the interaction of femoral head and acetabulum implant in which surface roughness effects are included. The model accounts for the elastic-plastic interaction of the implant surface roughness. For this purpose femoral head and acetabulum implants are considered as macroscopically spherical surfaces containing micron-scale roughness. Approximate equations are obtained that relate the contact force to the mean surface separation explicitly. Closed form equations are obtained for hysteretic energy loss in implant using the approximate equations.
文摘To study the influence of head-neck ratio and implant position on the range of motion (ROM) after total hip arthroplasty (THA).Methods In this study the author established a three-dimensional computerized model of hip joint and tested the range of motion of three different head-neck ratio after total hip arthroplasty.Results Range of motion after total hip arthroplasty depended on design parameters such as head-neck ratio,but also on the implantation parameters such as the cup’s inclination and antevertion,the stem’s antevertion and their combination of each other.Optimal range of motion required compliant position of total hip components.The range of motion increased with the enlarging of head-hnck ratio.Conclusion Higher head-neck ratio leads to optimal range of motion and decreased the prevalence of prosthetic impingement within compliant,well-defined combination of cup’s inclination,cup’s antevertion and stem’s antevertion depending on the intended ROM.Domestic magnesium-silicon jade total hip prosthesis has too low head-neck ratio to result in enough range of motion that fulfilled daily living after total hip arthroplasty.14 refs,4 figs,3 tabs.
文摘This paper presents a probabilistic approach for studying the reliability of cementless hip prostheses in the presence of mechanical uncertainties and its application to the investigation of the influence of bone-implant interface properties. The non-linear deterministic model of the bone-implant coupled system and its finite element implementation are described, and the proposed reliability analysis is exposed. It is demonstrated that the distribution (uniform, truncated Gaussian and truncated lognormal distribution) of the two chosen parameters and the truncation lengths have a minor influence on the Hasofer-Lind index. This index logically increases as the failure threshold increases. FORM and SORM approximations are compared with the results obtained using a crude Monte-Carlo method for the estimation of failure probability. The performance of three Monte-Carlo methods is studied in terms of the necessary number of FE calculations. The method based on the Directional Simulation (DS) technique is efficient and less time-consuming. The validity and operational capacity of the proposed approach would not be compromised by an increase in the number of uncertain parameters.
