A Better Understanding of the Surface Topography at the Stem-Cement Interface

2007 ◽  
Author(s):  
H. Zhang ◽  
L. Brown ◽  
L. Blunt
Keyword(s):  
Bone Cement ◽  
Surface Topography ◽  
Weak Link ◽  
Femoral Stem ◽  
Transitional Zone ◽  
In Vitro Test ◽  
Element Analysis ◽  
Cement Interface ◽  
Pull Out

The long term stabilization and durability of cemented total hip replacement (THR) depends on not only the bulk properties of the components but also the interfaces through which they interact. The stem-cement interface has been consistently considered as a weak link in the stem-cement-bone system, being a transitional zone between two materials with significantly different mechanical properties. Previous research concerning this interface has been limited to investigation of interfacial shear strength through in vitro test and finite element analysis (FEA). Until now, a deep insight into the contact characteristics at this interface, especially the interaction between femoral stems with various surface finishes and bone cement, has not been established. In addition, it is still an area of debate whether a permanent fixation can be achieved by utilizing a matt femoral stem, and furthermore it is another matter of concern that a matt femoral stem would cause much more damage to the cement mantle, resulting in an acceleration of aseptic loosening of the femoral stem. This present study investigated the surface topography of stainless steel rods and Simplex P bone cement obtained from a series of pull out tests in order to gain a better understanding of the interaction at the stem-cement interface.

scholarly journals In Vitro Fatigue Failure of Cemented Acetabular Replacements: A Hip Simulator Study

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
N. P. Zant ◽  
P. Heaton-Adegbile ◽  
J. G. Hussell ◽  
J. Tong
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bone Cement ◽  
Cement Mantle ◽  
Stair Climbing ◽  
Normal Walking ◽  
Element Analysis ◽  
Cement Interface ◽  
Hip Simulator

Although hip simulators for in vitro wear testing of prosthetic materials used in total hip arthroplasty (THA) have been available for a number of years, similar equipment has yet to appear for endurance testing of fixation in cemented THA, despite considerable evidence of late aseptic loosening as one of the most significant failure mechanisms in this type of replacements. An in vitro study of fatigue behavior in cemented acetabular replacements has been carried out, utilizing a newly developed hip simulator. The machine was designed to simulate the direction and the magnitude of the hip contact force under typical physiological loading conditions, including normal walking and stair climbing, as reported by Bergmann et al. (2001, Hip 98, Freie Universitaet, Berlin). A 3D finite element analysis has been carried out to validate the function of the hip simulator and to evaluate the effects of boundary conditions and geometry of the specimen on the stress distribution in the cement mantle. Bovine pelvic bones were implanted with a Charnley cup, using standard manual cementing techniques. Experiments were carried out under normal walking and descending stairs loading conditions with selected load levels from a body weight of 75–125kg. Periodically, the samples were removed from the test rigs to allow CT scanning for the purpose of monitoring damage development in the cement fixation. The hip simulator was found to be satisfactory in reproducing the hip contact force during normal walking and stair climbing, as reported by Bergmann et al. Finite element analysis shows that the stress distributions in the cement mantle and at the bone-cement interface are largely unaffected by the geometry and the boundary conditions of the model. Three samples were tested up to 17×106cycles and sectioned post-testing for microscopic studies. Debonding at the bone-cement interface of various degrees in the posterior-superior quadrant was revealed in these samples, and the location of the failures corresponds to the highest stressed region from the finite-element analysis. Preliminary experimental results from a newly developed hip simulator seem to suggest that debonding at the bone-cement interface is the main failure mechanism in cemented acetabular replacements, and descending stairs seem to be more detrimental than normal walking or ascending stairs with regard to fatigue integrity of cement fixation.

scholarly journals CAD-FEA modeling and fracture resistance of bilayer zirconia crowns manufactured by the rapid layer technology

2021 ◽  
Vol 32 (3) ◽  
pp. 44-55
Author(s):  
Julia Magalhães Costa Lima ◽  
Anna Karina Figueiredo Costa ◽  
Lilian Costa Anami ◽  
Karina Barbosa Souza ◽  
Nathalia Ramos da Silva ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Fracture Resistance ◽  
Resin Cement ◽  
In Vitro Test ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Cement Interface ◽  
Computer Aided ◽  
Cad Cam

Abstract In the RLT (Rapid Layer Technology), veneering ceramic and framework are fabricated by computer-aided design/computer-aided manufacturing (CAD/CAM) and then cemented to obtain the restoration. This study aimed to evaluate the effect of the thickness of veneering ceramic manufactured by the RLT technique on the fracture resistance (FR) of bilayer crowns with zirconia frameworks. Twenty zirconia frameworks and twenty feldspathic posterior crowns with two different veneering ceramic occlusal thicknesses (1mm=TF1; 2mm=TF2) were manufactured using CAD/CAM system. The specimens were luted to an epoxy resin abutment with resin cement and mechanically cycled (200N and 4.5×105 Pa, 37°C, 2×106 cycles, 3Hz). The FR test was performed (10kN, 0.5mm/min), and the specimens were analyzed in a stereomicroscope. For the stress analysis (finite element analysis, FEA), a 10kN load was equal to the in vitro test, and the principal stress was evaluated. The FR data were analyzed by Student’s t-test and Weibull's analysis. The thickness influenced the FR of bilayer crowns. The FR was higher in the TF2 than in the TF1 group. The TF2 group presented the highest characteristic strength compared to the group TF1. The predominant type of failure was delamination. The FEA showed higher stress concentrations below the loading application point at the veneering cement interface in the 1-mm-thick model. The bilayer crowns manufactured using the approach of 2mm of veneering ceramic promoted higher FR compared to the group with 1mm veneering ceramic. Also, the FEA showed that the veneer ceramic thickness has an effect on stress distribution in zirconia-based bilayer crowns.

Investigation of Protein Adsorption Mechanism and Biotribological Properties at Simulated Stem-Cement Interface

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Hongyu Zhang ◽  
Shaohua Zhang ◽  
Jianbin Luo ◽  
Yuhong Liu ◽  
Shanhua Qian ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Bone Cement ◽  
Protein Adsorption ◽  
Adsorption Mechanism ◽  
Calf Serum ◽  
Femoral Stem ◽  
Sudden Increase ◽  
Cement Interface ◽  
Surface Finishes

Debonding of the stem–cement interface occurs inevitably for almost all stem designs under physiological loading, and the wear debris generated at this interface is showing an increasing significance in contributing to the mechanical failure of cemented total hip replacements. However, the influence of protein adsorption onto the femoral stem and the bone cement surfaces has not been well taken into consideration across previous in vitro wear simulations. In the present study, the protein adsorption mechanism and biotribological properties at the stem-cement interface were investigated through a series of frictional tests using bone cements and femoral stems with two kinds of surface finishes, lubricated by calf serum at body temperature. The friction coefficient was dependent on the surface finish of the samples, with an initial much lower value obtained for the polished contacting pairs followed by a sudden increase in the friction coefficient with regard to the tests performed at higher frequencies. The friction coefficient did not change much during the tests for the glass-bead blasted contacting pairs. In addition, proteins from the calf serum were found to adsorb onto both the femoral stem and the bone cement surfaces, and the thickness of the physically adsorbed proteins on the polished metallic samples was more than 10 μm, which was measured using an optical interferometer and validated through a vertical scanning methodology based on Raman spectroscopy. An initial protein adsorption mechanism and biotribological properties at the stem-cement interface were examined in this study, and it suggested that wear at the stem-cement interface may be postponed or reduced by tailoring physicochemical properties of the femoral components to promote protein adsorption.

Axisymmetric Finite Element Analysis of a Debonded Total Hip Stem With an Unsupported Distal Tip

1996 ◽  
Vol 118 (3) ◽  
pp. 399-404 ◽  
Author(s):  
T. L Norman ◽  
V. C. Saligrama ◽  
K. T. Hustosky ◽  
T. A. Gruen ◽  
J. D. Blaha
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Relaxation ◽  
Bone Cement ◽  
Cement Mantle ◽  
Load Level ◽  
Interface Conditions ◽  
Element Analysis ◽  
Cement Interface ◽  
Total Hip

A tapered femoral total hip stem with a debonded stem-cement interface and an unsupported distal tip subjected to constant axial load was evaluated using two-dimensional (2D) axisymmetric finite element analysis. The analysis was performed to test if the mechanical condition suggest that a “taper-lock” with a debonded viscoelastic bone cement might be an alternative approach to cement fixation of stem type cemented hip prosthesis. Effect of stem-cement interface conditions (bonded, debonded with and without friction) and viscoelastic response (creep and relaxation) of acrylic bone cement on cement mantle stresses and axial displacement of the stem was also investigated. Stem debonding with friction increased maximum cement von Mises stress by approximately 50 percent when compared to the bonded stem. Of the stress components in the cement mantle, radial stresses were compressive and hoop stresses were tensile and were indicative of mechanical taper-lock. Cement mantle stress, creep and stress relaxation and stem displacement increased with increasing load level and with decreasing stem-cement interface friction. Stress relaxation occur predominately in tensile hoop stress and decreased from 1 to 46 percent over the conditions considered. Stem displacement due to cement mantle creep ranged from 614 μm to 1.3 μm in 24 hours depending upon interface conditions and load level.

Shape Optimization of Femoral Components of an Artificial Hip Prosthesis Using the Three-Dimensional P-Version Finite Element Study and the In Vitro Measurement of Strain in the Bone Cement

2002 ◽  
Author(s):  
Masaru Higa ◽  
Ikuya Nishimura ◽  
Kazuhiro Matsuda ◽  
Hiromasa Tanino ◽  
Yoshinori Mitamura
Keyword(s):  
Finite Element ◽  
Shape Optimization ◽  
Bone Cement ◽  
Femoral Component ◽  
Three Dimensional ◽  
Femoral Stem ◽  
Cement Mantle ◽  
Optimum Shape ◽  
Shear Stresses

Though Total Hip Arthroplasty (THA) is being performed with greater frequency every year for patients with endstage arthritis of hip, mechanical fatigue of bone cement leading to damage accumulation is implicated in the loosening of cemented hip components. This fatigue failure of bone cement has been reported to be the result of high tensile and shear stresses at the bone cement. The aim of this study is to design the optimum shape of femoral component of a THA that minimizes the peak stress value of maximum principal stress at the bone cement and to validate the FEM results by comparing numerical stress with experimental ones. The p-version three-dimensional Finite Element Method (FEM) combined with an optimization procedure was used to perform the shape optimization. Moreover the strain in the cement mantle surrounding the cemented femoral component of a THA was measured in vitro using strain gauges embedded within the cement mantle adjacent to the developed femoral stem to validate the optimization results of FEM.

scholarly journals Osseointegration of Antimicrobial Acrylic Bone Cements Modified with Graphene Oxide and Chitosan

2020 ◽  
Vol 10 (18) ◽  
pp. 6528 ◽  
Author(s):  
Mayra Eliana Valencia Zapata ◽  
José Herminsul Mina Hernandez ◽  
Carlos David Grande Tovar ◽  
Carlos Humberto Valencia Llano ◽  
Blanca Vázquez-Lasa ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Bone Cement ◽  
Orthopedic Surgery ◽  
Bending Strength ◽  
Orthopedic Implants ◽  
Parietal Bone ◽  
Maximum Temperature ◽  
Cement Interface

Acrylic bone cement (ABC) is one of the most used materials in orthopedic surgery, mainly for the fixation of orthopedic implants to the bone. However, ABCs usually present lack of biological activity and osseointegration capacity that leads to loosening of the prosthesis. This work reports the effect of introducing graphene oxide (GO) and chitosan (CS), separately or together, in the ABC formulation on setting performance, mechanical behavior, and biological properties. Introduction of both CS and GO to the ABC decreased the maximum temperature by 21% and increased the antibacterial activity against Escherichia coli by 87%, while introduction of only CS decreased bending strength by 32%. The results of cell viability and cell adhesion tests showed in vitro biocompatibility. The in vivo response was investigated using both subdermal and bone parietal implantations in Wistar rats. Modified ABCs showed absence of immune response, as confirmed by a normal inflammatory response in Wistar rat subdermal implantation. The results of the parietal bone implantation showed that the addition of CS and GO together allowed a near total healing bone–cement interface, as observed in the micrographic analysis. The overall results support the great potential of the modified ABCs for application in orthopedic surgery mainly in those cases where osseointegration is required.

The in vitro Measurement of Bone-Cement Interface Pressures and Shear Strengths in the Femur: A Comparison of two Cementation Methods

1995 ◽  
Vol 5 (3-4) ◽  
pp. 124-130 ◽  
Author(s):  
A. J. Ward ◽  
E. J. Smith ◽  
J. W. Barlow ◽  
A. Powell ◽  
M. Halawa ◽  
...  
Keyword(s):  
Bone Cement ◽  
Hip Arthroplasty ◽  
High Viscosity ◽  
Femoral Bone ◽  
Cement Interface ◽  
Cement Injection ◽  
Paired Samples ◽  
In Vitro Simulation ◽  
Interface Pressures

Two differing cementation methods were investigated in an in vitro simulation of hip arthroplasty. The bone-cement interface pressures were recorded during cement injection and stem insertion in matched pairs of fresh cadaveric femora. Reduced viscosity cement injected with a cement gun and proximal seal was compared with injection of high viscosity cement and finger-packing in each pair. The resultant shear strength of the bone-cement interface was measured by push-out tests. Results were analysed using the Wilcoxon ranked sum test for paired samples. The Exeter method of cementation produced significantly higher mean and maximum pressures above the bleeding pressure of femoral bone at all interface levels during cement injection. This was associated with significantly greater mean shear strengths. The authors conclude that the Exeter pressurization system for cementation overcomes the effect of femoral bone bleeding and improves the quality of the bone-cement interface. This may contribute to reduction in the incidence of loosening in cement hip arthroplasty.

scholarly journals Reproduction of fretting wear at the stem—cement interface in total hip replacement

2007 ◽  
Vol 221 (8) ◽  
pp. 963-971 ◽  
Author(s):  
L Brown ◽  
H Zhang ◽  
L Blunt ◽  
S Barrans
Keyword(s):  
Bone Cement ◽  
Total Hip Replacement ◽  
Hip Replacement ◽  
Fatigue Cracks ◽  
Cement Mantle ◽  
Fretting Wear ◽  
Cement Interface ◽  
Total Hip

The stem-cement interface experiences fretting wear in vivo due to low-amplitude oscillatory micromotion under physiological loading, as a consequence it is considered to play an important part in the overall wear of cemented total hip replacement. Despite its potential significance, in-vitro simulation to reproduce fretting wear has seldom been attempted and even then with only limited success. In the present study, fretting wear was successfully reproduced at the stem-cement interface through an in-vitro wear simulation, which was performed in part with reference to ISO 7206-4: 2002. The wear locations compared well with the results of retrieval studies. There was no evidence of bone cement transfer films on the stem surface and no fatigue cracks in the cement mantle. The cement surface was severely damaged in those areas in contact with the fretting zones on the stem surface, with retention of cement debris in the micropores. Furthermore, it was suggested that these micropores contributed to initiation and propagation of fretting wear. This study gave scope for further comparative study of the influence of stem geometry, stem surface finish, and bone cement brand on generation of fretting wear.

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