title: Factors contributing to rapid wear and osteolysis in hips with modular acetabular bearings made of hylamer.
abstract: There have been several reports of osteolysis associated with rapid wear of Hylamer. A detailed analysis of retrieved implants and tissues can identify factors contributing to rapid wear and osteolysis. The mean linear wear rate of 12 liners was 0.49 mm/y, and 11 of 12 hips had progressive retroacetabular osteolysis. The average patient age was 50 years, and the mean implantation time was 50 months. All liners were sterilized by gamma irradiation in air. There was an 11-month difference in the average shelf-life of the 3 liners that were white and those that were darker in color. The volumetric wear rate of the white liners was 30% less than that of the others, suggesting a difference in the wear resistance of the liners as a function of shelf life. The mean average surface roughness (Ra) and the mean maximum surface roughness (R(max)) of the femoral heads were increased 3-fold and 50-fold compared with typical values for unused femoral heads. Evidence of 3-body wear, such as metal particles embedded in the liners, was commonly present. The pattern of backside liner deformation and burnishing was consistent with relative motion between the liner and the shell. In addition to generating Hylamer wear particles, repetitive axial motion between the liner and shell could generate fluid pressure, which transmitted through holes in the acetabular shell could cause or contribute to the development of retroacetabular osteolysis. Hylamer particles of variable shape and size, consistent with generation by several wear modes, were isolated from periprosthetic tissues.
authors.affiliation: Joint Replacement Institute at Orthopaedic Hospital, Los Angeles, California 90007, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Scott
authors.forename: P A
authors.initials: PA
authors.lastname: Campbell
authors.forename: C D
authors.initials: CD
authors.lastname: McClung
authors.forename: T P
authors.initials: TP
authors.lastname: Schmalzried
mesh_terms: D000077:Acetabulum; D019644:Arthroplasty, Replacement, Hip; D019544:Equipment Failure Analysis; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000209:etiology*; D020959:Polyethylene; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D013314:Stress, Mechanical; D013997:Time Factors
chemical_list: D020959:Polyethylene