Finite Element Analysis on Wear of Hip Prosthesis Considering Creep under Different Physiological Activities
Objective To investigate the creep effect of ultrahigh-molecular-weight polyethylene(UHMWPE)liners on the wear of hip prostheses under different physiological activities.Methods A finite element model of a cobalt-chrome alloy(CoCr)head and UHMWPE liner was established and validated.The effects of the ISO 14242 standard gait and daily activities(standing up/sitting down,climbing stairs,and knee bending)on prosthesis wear and creep were compared and analyzed.Results Under the ISO 14242 standard gait,the maximum contact pressure of the liner decreased from 18.3 MPa to 12.2 MPa when creep was not considered,and from 15.3 MPa to 14.2 MPa when creep was considered.The maximum linear penetration depths owing to wear and creep were 0.47 mm and 0.11 mm,respectively,with a wear volume of 205 mm3.The wear under different physiological activities was ranked as follows:climbing stairs>standing up/sitting down>ISO standard gait>knee flexion.The creep was ranked as follows:ISO standard gait>stair climbing>knee bending>standing up/sitting.Conclusions The wear and creep of the acetabular liner differed significantly under different physiological activities.The maximum contact pressure of the UHMWPE liner was reduced by the creep effect.This,in turn,decreased the wear volume.Both creep and wear should be considered in the design of hip prostheses to optimize their performance and extend their service life.
artificial hip jointwearcreepphysiological activitiesfinite element analysis
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