title: Clinical fracture of cross-linked UHMWPE acetabular liners.
abstract: Highly cross-linked ultrahigh molecular weight polyethylene (UHMWPE) is increasingly used as a bearing material in total hip replacements. Cross-linking of UHMWPE has been shown to increase wear resistance but decrease its fracture resistance. We analyzed the clinical fracture failure of four cross-linked UHMWPE total hip replacement components of four different designs via microscopic observation of the fracture surfaces, and found that in all cases fractures initiated at stress concentrations in an unsupported region of the component (termed the elevated rim). Finite element analyses (FEA) of each individual implant design were then conducted. Results from this analysis demonstrated that the predicted magnitude and orientation of maximum principal stress due to mechanical loading of the elevated rim was sufficient to propagate initiated fatigue cracks in each case. FEA also predicted that cracks may arrest after some amount of growth due to a steep stress gradient near the initiation site. Further, while anatomical positioning of the implant and material properties affect the risk of fracture, we examined whether these failures are strongly related to the notched elevated rim design feature that is common to the four failed cases presented here. We believe that cross-linked UHMWPE remains an excellent bearing material for total hip replacements but that designs employing this material should mitigate stress concentrations or other design features that increase the risk of fracture.
authors: Case Western Reserve University, Mechanical and Aerospace Engineering, 414 Glennan, CWRU, 10900 Euclid Ave., Cleveland, OH 44106, USA. jevanf@gmail.com
authors: Jevan
authors: J
authors: Furmanski
authors: Martin
authors: M
authors: Anderson
authors: Sonny
authors: S
authors: Bal
authors: A Seth
authors: AS
authors: Greenwald
authors: David
authors: D
authors: Halley
authors: Brad
authors: B
authors: Penenberg
authors: Michael
authors: M
authors: Ries
authors: Lisa
authors: L
authors: Pruitt
mesh_terms: D000077:Acetabulum / Q000601:surgery*; D000328:Adult; D000368:Aged; D003432:Cross-Linking Reagents / Q000737:chemistry; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008875:Middle Aged; D011095:Polyethylenes / Q000737:chemistry*; D011474:Prosthesis Design; D011475:Prosthesis Failure
chemical_list: D003432:Cross-Linking Reagents; D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene