title: Total hip wear assessment: a comparison between computational and in vitro wear assessment techniques using ISO 14242 loading and kinematics.
abstract: In the present study a direct comparison was made between in vitro total hip wear testing and a computational analysis considering the effects of time and a nonlinear stress-strain relationship for ultrahigh molecular weight polyethylene (UHMWPE) at 37 degrees C. The computational simulation was made correct through calibration to experimental volumetric wear results, and the predicted damage layout on the acetabular liner surface was compared with results estimated from laser scanning of the actual worn specimens. The wear rates for the testing specimens were found to be 17.14+/-1.23 mg/10(6) cycles and 19.39+/-0.79 mg/10(6) cycles, and the cumulative volumetric wear values after 3x10(6) cycles were 63.70 mm(3) and 64.02 mm(3) for specimens 1 and 2, respectively. The value of the calibrated wear coefficient was found to be 5.32(10(-10)) mm(3)/N mm for both specimens. The major difference between the computational and experimental wear results was the existence of two damage vectors in the experimental case. The actual location of damage was virtually the same in both cases, and the maximum damage depth of the computational model agreed well with the experiment. The existence of multiple wear vectors may indicate the need for computational approaches to account for multidirectional sliding or strain hardening of UHMWPE. Despite the limitation in terms of describing the overall damage layout, the present computational model shows that simulation can mimic some of the behavior of in vitro wear.
authors.affiliation: Department of Mechanical and Materials Engineering, Queen's University, McLaughlin Hall 305, 130 Stuart Street, Kingston, ON, K7L 3N6, Canada. george@traxtal.com
authors.forename: George
authors.initials: G
authors.lastname: Matsoukas
authors.forename: Ryan
authors.initials: R
authors.lastname: Willing
authors.forename: Il Yong
authors.initials: IY
authors.lastname: Kim
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods*; D001696:Biomechanical Phenomena; D002138:Calibration; D003198:Computer Simulation; D019544:Equipment Failure Analysis / Q000379:methods*; D020342:Finite Element Analysis; D006622:Hip Prosthesis; D006801:Humans; D008970:Molecular Weight; D020959:Polyethylene / Q000737:chemistry; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D013696:Temperature; D016474:Weight-Bearing
chemical_list: D020959:Polyethylene