The influence of component design, bearing clearance and axial load on the squeaking characteristics of ceramic hip articulations

Journal
Journal of biomechanics  
Volume
44
Issue
5
Start Page
837
End Page
841
Citation
Journal of Biomechanics 44 (5): 837-841 (2011)
Publisher DOI
10.1016/j.jbiomech.2010.12.012
Scopus ID
2-s2.0-79952043319
Publisher
Elsevier Science
Squeaking of hip replacements with ceramic-on-ceramic bearings has put the use of this material into question despite its superior wear behavior. Squeaking has been related to implant design. The purpose of this study was to determine the influence of particular acetabular cup and femoral stem designs on the incidence of squeaking and its characteristics. The dynamic behavior of the stem, head and stem assembled with head was investigated by determining their eigenfrequencies using experimental and numerical modal analysis. Four different stem and three different cup designs were investigated. Operational system vibrations resulting in audible squeaking were reproduced in a hip simulator and related to the respective component eigenfrequencies. The applied joint load and bearing clearance were varied in the clinically relevant range.Stems with lower eigenfrequencies were related to lower squeaking frequencies and increased acoustic pressure (loudness), and therefore to a higher susceptibility to squeaking. Higher load increased the squeaking frequency, while the acoustic pressure remained unchanged. No influence of the clearance or the cup design was found.Stem design was found to have an important influence on squeaking characteristics and its incidence, confirming and explaining similar clinical observations. Cup design itself was found to have no major influence on the dynamic behavior of the system but plays an important indirect role in influencing the magnitude of friction: Squeaking only occurs if the friction in the joint articulation is sufficient to excite vibrations to audible magnitudes. If friction is low, no squeaking occurs with any of the designs investigated.
Subjects
Eigenfrequency
Hip prosthesis
In vitro
Simulator
Squeaking
DDC Class
570: Life Sciences, Biology
610: Medicine, Health
More Funding Information
Financial funding was kindly received by Ceramtec.