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Wear performance of ceramic-on-metal hip bearings.

Reinders J, Sonntag R, Heisel C, Reiner T, Vot L, Kretzer JP - PLoS ONE (2013)

Bottom Line: Although, CoM shows lower wear rates than MoM, in-vitro wear testing of CoM shows widely varying results.The results showed no differences in mean wear rates between CoM and CoC bearings.Therefore, high variations in wear rates as seen in this study, even at low levels, may have an adverse effect on the in-vivo wear behavior.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biomechanics and Implant Research, Department of Orthopedics and Traumatology, Heidelberg University Hospital, Heidelberg, Germany. joern.reinders@med.uni-heidelberg.de

ABSTRACT
Ceramic-on-metal (CoM) bearings are considered to be a promising alternative to polyethylene-based bearings or hard-on-hard bearings (Ceramic-on-Ceramic (CoC) and Metal-on-Metal (MoM)). Although, CoM shows lower wear rates than MoM, in-vitro wear testing of CoM shows widely varying results. This may be related to limitations of wear-measuring methods. Therefore, the aim of this study was to improve the gravimetric measurement technique and to test wear behaviour of CoM bearings compared to CoC bearings. Level walking according to ISO-14242 was simulated for four CoM and four CoC bearings. Prior to simulation, errors in measurement of gravimetric wear were detected and improvements in measurement technique incorporated. The results showed no differences in mean wear rates between CoM and CoC bearings. However, the CoM bearings showed wear results over a wide range of wear performance. High reliability of wear results was recorded for the CoC bearings. Material transfer was observed on the ceramic heads of the CoM bearings. Therefore, for level walking a partial mixed or boundary lubrication has to be assumed for this type of bearing. CoM is a highly sensitive wear-couple. The reasons for the observed behaviour cannot be clarified from this study. Simulator studies have to be considered as an ideal loading condition. Therefore, high variations in wear rates as seen in this study, even at low levels, may have an adverse effect on the in-vivo wear behavior. Careful clinical use may be advisable until the reasons for the variation are fully clarified and understood.

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Head of CoM bearing (left) and CoC bearing (right).
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pone-0073252-g003: Head of CoM bearing (left) and CoC bearing (right).

Mentions: Ceramic heads from the CoM bearings showed visible signs of metallic transfer in the form of stripes. For the ceramic heads of CoM bearings, the subjective amount of material transfer was higher for bearings with higher wear rates compared to the low-wearing CoM bearings. In comparison, no visible traces were found on the CoC heads (Figure 3).


Wear performance of ceramic-on-metal hip bearings.

Reinders J, Sonntag R, Heisel C, Reiner T, Vot L, Kretzer JP - PLoS ONE (2013)

Head of CoM bearing (left) and CoC bearing (right).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3756941&req=5

pone-0073252-g003: Head of CoM bearing (left) and CoC bearing (right).
Mentions: Ceramic heads from the CoM bearings showed visible signs of metallic transfer in the form of stripes. For the ceramic heads of CoM bearings, the subjective amount of material transfer was higher for bearings with higher wear rates compared to the low-wearing CoM bearings. In comparison, no visible traces were found on the CoC heads (Figure 3).

Bottom Line: Although, CoM shows lower wear rates than MoM, in-vitro wear testing of CoM shows widely varying results.The results showed no differences in mean wear rates between CoM and CoC bearings.Therefore, high variations in wear rates as seen in this study, even at low levels, may have an adverse effect on the in-vivo wear behavior.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biomechanics and Implant Research, Department of Orthopedics and Traumatology, Heidelberg University Hospital, Heidelberg, Germany. joern.reinders@med.uni-heidelberg.de

ABSTRACT
Ceramic-on-metal (CoM) bearings are considered to be a promising alternative to polyethylene-based bearings or hard-on-hard bearings (Ceramic-on-Ceramic (CoC) and Metal-on-Metal (MoM)). Although, CoM shows lower wear rates than MoM, in-vitro wear testing of CoM shows widely varying results. This may be related to limitations of wear-measuring methods. Therefore, the aim of this study was to improve the gravimetric measurement technique and to test wear behaviour of CoM bearings compared to CoC bearings. Level walking according to ISO-14242 was simulated for four CoM and four CoC bearings. Prior to simulation, errors in measurement of gravimetric wear were detected and improvements in measurement technique incorporated. The results showed no differences in mean wear rates between CoM and CoC bearings. However, the CoM bearings showed wear results over a wide range of wear performance. High reliability of wear results was recorded for the CoC bearings. Material transfer was observed on the ceramic heads of the CoM bearings. Therefore, for level walking a partial mixed or boundary lubrication has to be assumed for this type of bearing. CoM is a highly sensitive wear-couple. The reasons for the observed behaviour cannot be clarified from this study. Simulator studies have to be considered as an ideal loading condition. Therefore, high variations in wear rates as seen in this study, even at low levels, may have an adverse effect on the in-vivo wear behavior. Careful clinical use may be advisable until the reasons for the variation are fully clarified and understood.

Show MeSH
Related in: MedlinePlus