Understanding the differences between the wear of metal-on-metal and ceramic-on-metal total hip replacements

2008 ◽  
Vol 222 (3) ◽  
pp. 285-296 ◽  
Author(s):  
C G Figueiredo-Pina ◽  
Y Yan ◽  
A Neville ◽  
J Fisher
Keyword(s):  
Open Circuit ◽  
Long Term Results ◽  
Cobalt Chromium ◽  
Material Loss ◽  
Hip Simulator ◽  
Metal On Metal ◽  
Hip Replacements ◽  
Efficient Alternative

Hip simulator studies have been carried out extensively to understand and test artificial hip implants in vitro as an efficient alternative to obtaining long-term results in vivo. Recent studies have shown that a ceramic-on-metal material combination lowers the wear by up to 100 times in comparison with a typical metal-on-metal design. The reason for this reduction remains unclear and for this reason this study has undertaken simple tribometer tests to understand the fundamental material loss mechanisms in two material combinations: metal-on-metal and ceramic-on-ceramic. A simple-configuration reciprocating pin-on-plate wear study was performed under open-circuit potential (OCP) and with applied cathodic protection (CP) in a serum solution using two tribological couples: firstly, cobalt—chromium (Co—Cr) pins against Co—Cr plates; secondly, Co—Cr pins against alumina (Al2O3) plates. The pin and plate surfaces prior to and after testing were examined by profilometry and scanning electron microscopy. The results showed a marked reduction in wear when CP was applied, indicating that total material degradation under the OCP condition was attributed to corrosion processes. The substitution of the Co—Cr pin with an Al2O3 plate also resulted in a dramatic reduction in wear, probably due to the reduction in the corrosion—wear interactions between the tribological pair.

scholarly journals Does modularity of metal-on-metal hip implants increase cobalt: chromium ratio?

2019 ◽  
pp. 112070001987363
Author(s):  
Kevin C Ilo ◽  
Karim Aboelmagd ◽  
Harry S Hothi ◽  
Asaad Asaad ◽  
John A Skinner ◽  
...  
Keyword(s):  
Metal Ion ◽  
Hip Implants ◽  
Cobalt Chromium ◽  
Metal Debris ◽  
Material Loss ◽  
Total Hip ◽  
Modular Stem ◽  
Metal On Metal ◽  
Hip Replacements ◽  
Hip Arthroplasties

Background: Blood metal ion levels are used in the surveillance of metal-on-metal (MoM) hip implants. Modular implants contain an extra source of metal debris that may affect the ratio of metal ions in the blood. Methods: This was a retrospective study of 503 patients with hip replacements made by a single manufacturer (Smith & Nephew, Warwick, UK) with the same bearing surface. There were 54 total hip arthroplasties, 35 Birmingham Mid-Head Resections and 414 hip resurfacings. Whole blood metal ion levels and their ratios were analysed to investigate the effect of a modular junction. Results: The cobalt:chromium ratios were greater in the total hip arthroplasty group (mean 2.3:1) when compared to the resurfacings group (mean 1.3:1, p = <0.05) and Birmingham Mid-Head Resection group (mean 1.1:1, p = 0.11). Conclusions: This study demonstrated a trend for a higher cobalt:chromium ratio in patients with MoM total hip replacement that may be due to metal debris from the modular stem-head junction. Further work is required to correlate clinical data with retrieval analysis to confirm the effect of taper material loss on the cobalt:chromium ratio.

Wear Simulation of Metal on Metal Hip Replacements: An Analytical Approach

2012 ◽  
Author(s):  
Lorenza Mattei ◽  
Francesca Di Puccio ◽  
Enrico Ciulli
Keyword(s):  
Hip Replacement ◽  
Experimental Tests ◽  
Wear Model ◽  
Wear Rates ◽  
Metal On Metal ◽  
Hip Replacements ◽  
Wear Law ◽  
Implant Wear

Hip replacement failure is mainly attributable to the implant wear. Consequently preclinical wear evaluations are extremely important. As experimental tests are attractive but highly cost/time demanding, several predictive models have been proposed mainly based on finite element simulations and for metal on plastic (MoP) implants. The aim of this study is to develop a mathematical wear model of metal on metal prostheses, revision of the previous one for MoP implants, developed by the same authors. The model, based on the Archard wear law and on the Hertzian theory, was applied to compare a total (THR) and a resurfacing (RHR) hip replacement under both in vivo and in vitro gait conditions. The results were in agreement with the literature predicting wear rates significantly higher for the RHR than for the THR. The effect of the boundary conditions on wear rates/maps was also investigated and the model limitations discussed.

Long-Term Survival of Stanmore Total Hip Replacements Inserted with Radiolucent Bone Cement

2002 ◽  
Vol 12 (3) ◽  
pp. 274-280
Author(s):  
J.A. Wimhurst ◽  
J.L. Hobby ◽  
C.P. Roberts ◽  
A.N. Gibbs ◽  
L.J. Deliss ◽  
...  
Keyword(s):  
Bone Cement ◽  
In Vivo Studies ◽  
Long Term Results ◽  
Term Survival ◽  
Total Hip ◽  
Total Hip Replacements ◽  
Hip Replacements

Radio-opacifiers in bone cements are an accepted part of every-day practice. They have, however, been shown to be a potential cause of an increase in third body wear and to excite bone resorption in in vitro and in vivo studies. We reviewed the results of 228 consecutive Stanmore total hip replacements performed between 1981 and 1985 in 211 patients. All were inserted with radiolucent bone cement. Information regarding whether the prosthesis had been revised was available for all patients. Seventy-three patients (83 hips) were still alive and 41 patients (44 hips) were sufficiently healthy to attend clinic. Information regarding pain level was obtained from the remaining 32 patients. When revision of the implant was taken as the end-point, there was 95% ten-year survival, 91% fifteen-year survival and 75% eighteen-year survival. These long-term results of Stanmore THRs, performed in a district general hospital, with radiolucent bone cement, compare favourably with the other published series for this implant. We did not find the inability to see the bone cement a particular disadvantage when reviewing radiographs for signs of loosening.

Influence of particulate and dissociated metal-on-metal hip endoprosthesis wear on mesenchymal stromal cells in vivo and in vitro

Biomaterials ◽  
2016 ◽  
Vol 98 ◽  
pp. 31-40 ◽  
Author(s):  
Anastasia Rakow ◽  
Janosch Schoon ◽  
Anke Dienelt ◽  
Thilo John ◽  
Martin Textor ◽  
...  
Keyword(s):  
Mesenchymal Stromal Cells ◽  
Stromal Cells ◽  
Hip Endoprosthesis ◽  
Metal On Metal

scholarly journals The Effect of Ca on In Vitro Behavior of Biodegradable Zn-Fe Alloy in Simulated Physiological Environments

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1624
Author(s):  
Orit Avior ◽  
Noa Ben Ghedalia-Peled ◽  
Tomer Ron ◽  
Razi Vago ◽  
Eli Aghion
Keyword(s):  
Corrosion Rate ◽  
Metabolic Activity ◽  
Electrochemical Analysis ◽  
Open Circuit ◽  
Hydrogen Gas ◽  
Hardness Tests ◽  
Fe Alloys ◽  
Cytotoxicity Assessment

The growing interest in Zn based alloys as structural materials for biodegradable implants is mainly attributed to the excellent biocompatibility of Zn and its important role in many physiological reactions. In addition, Zn based implants do not tend to produce hydrogen gas in in vivo conditions and hence do not promote the danger of gas embolism. However, Zn based implants can provoke encapsulation processes that, practically, may isolate the implant from its surrounding media, which limits its capability of performing as an acceptable biodegradable material. To overcome this problem, previous research carried out by the authors has paved the way for the development of Zn-Fe based alloys that have a relatively increased corrosion rate compared to pure Zn. The present study aims to evaluate the effect of 0.3–1.6% Ca on the in vitro behavior of Zn-Fe alloys and thus to further address the encapsulation problem. The in vitro assessment included immersion tests and electrochemical analysis in terms of open circuit potential, potentiodynamic polarization, and impedance spectroscopy in phosphate buffered saline (PBS) solution at 37 °C. The mechanical properties of the examined alloys were evaluated by tension and hardness tests while cytotoxicity properties were examined using indirect cell metabolic activity analysis. The obtained results indicated that Ca additions increased the corrosion rate of Zn-Fe alloys and in parallel increased their strength and hardness. This was mainly attributed to the formation of a Ca-rich phase in the form CaZn13. Cytotoxicity assessment showed that the cells’ metabolic activity on the tested alloys was adequate at over 90%, which was comparable to the cells’ metabolic activity on an inert reference alloy Ti-6Al-4V.

scholarly journals Ion Leaching from Implantable Medical Devices

2010 ◽  
Vol 638-642 ◽  
pp. 754-759
Author(s):  
Lawrence E. Eiselstein ◽  
Robert D. Caligiuri
Keyword(s):  
Medical Devices ◽  
Stainless Steels ◽  
The Body ◽  
Cobalt Chromium ◽  
Implantable Medical Devices ◽  
Device Development ◽  
Soluble Ions ◽  
Chromium Alloys

Implantable medical devices must be able to withstand the corrosive environment of the human body for 10 or more years without adverse consequences. Most reported research and development has been on developing materials and devices that are biocompatible and resistant to corrosion-fatigue, pitting, and crevice corrosion. However, little has been directly reported regarding implantable materials with respect to the rate at which they generate soluble ions in-vivo. Most of the biocompatibility studies have been done by examining animal implants and cell cultures rather than examining the rate at which these materials leach ions into the body. This paper will discuss what is currently known about the rate at which common implant materials (such as stainless steels, cobalt-chromium alloys, and nitinol) elute ions under in vitro conditions, what the limitations are of such data, and how this data can be used in medical device development.

Quantification of self-polishing in vivo from explanted metal-on-metal total hip replacements

2011 ◽  
Vol 44 (5) ◽  
pp. 513-516 ◽  
Author(s):  
Thomas J. Joyce ◽  
Harry Grigg ◽  
David J. Langton ◽  
Antoni V.F. Nargol
Keyword(s):  
Total Hip ◽  
Total Hip Replacements ◽  
Metal On Metal ◽  
Hip Replacements

Can cobalt levels estimate in-vivo wear of metal-on-metal bearings used in hip arthroplasty?

2007 ◽  
Vol 221 (8) ◽  
pp. 929-942 ◽  
Author(s):  
M Khan ◽  
J H Kuiper ◽  
J B Richardson
Keyword(s):  
Clinical Studies ◽  
Wear Debris ◽  
Metal Ion ◽  
Large Diameter ◽  
Small Diameter ◽  
Wear Rates ◽  
Hip Simulator ◽  
Metal On Metal ◽  
Metal Levels

High levels of cobalt and chromium ions are detected in the blood and urine of patients with metal-on-metal (MoM) hip replacement. These elements are released as a result of wear at the bearing surfaces. Wear rates depend on a multitude of factors, which include the bearing geometry, carbon content, manufacturing processes, lubrication, speed and direction of sliding of the surfaces, pattern of loading, and orientation of the components. In-vivo wear of MoM bearings cannot be reliably measured on X-rays because no distinction can be made between the bearing surfaces. Hip simulator studies have shown that wear rates are higher during the initial bedding-in phase and subsequently drop to very low levels. Accordingly, metal ion levels would be expected to decrease with the use of the bearing, measured as implantation time following surgery. However, several clinical studies have found that metal ion levels either gradually rise or fluctuate instead of decreasing to lower levels. Moreover, hip simulator studies predict that large-diameter bearings have lower wear rates than small-diameter bearings. In clinical studies, however, metal levels in patients with large-diameter bearings are unexpectedly higher than those in patients with small-diameter bearings. As a consequence, high cobalt ion levels in patients do not necessarily imply that their MoM bearings produce much wear debris at the time that their levels were measured; it may simply be due to accumulation of wear debris from the preceding time. Exercise-related cobalt rise may overcome this limitation and give a better assessment of the current wear status of a MoM bearing surface than a measure of cobalt levels only.

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