title: On the molecular interaction between femoral heads and polyethylene liners in artificial hip joints: phenomenology and molecular scale phenomena.
abstract: The chemical interaction of femoral heads with polyethylene liners is an important new area of research in total hip arthroplasty (THA) as a consequence of an unabating quest for elongated artificial joint lifetimes. It is a topic that goes beyond simple mechanical behavior or wear. It seeks to describe the prosthetic device as a whole by adding chemical considerations to mechanics and abrasion. One of the poorly understood chemical interactions is oxygen affinity of the femoral heads. While oxygen unavoidably diffuses into the non-crystalline enclaves of the polyethylene liner as a result of its contact with the tribolayer, a ceramic femoral head can either attract or release oxygen due to its tribochemical interactions. In this study, changes in liner crystallinity and oxidation were observed during simple static contact with different femoral heads within a hydrothermal environment. Examinations were made using Raman microprobe spectroscopy coupled with nanometer-scale spectroscopic analyses (x-ray photoelectron spectroscopy (XPS) and cathodoluminescence (CL) spectroscopy) on different sets of ceramic and polyethylene couples exposed for increasing periods to a hydrothermal environment. Even in the absence of frictional loading, structural modifications were clearly detected, statistically validated, and correlated with the oxygen affinity of various femoral head materials. It was found that oxide (Al2O3, Al2O3/ZrO2, and m-ZrO2) and non-oxide (Si3N4) ceramic heads release or attract nascent oxygen species, respectively. This research unequivocally identified a new gap in our knowledge of THA biomaterial interactions, with future studies and material improvements undoubtedly leading to an increase in longevity for prosthetic joints.
authors.affiliation: Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pezzotti
authors.forename: B Sonny
authors.initials: BS
authors.lastname: Bal
authors.forename: Elisa
authors.initials: E
authors.lastname: Casagrande
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Sugano
authors.forename: Bryan J
authors.initials: BJ
authors.lastname: McEntire
authors.forename: Wenliang
authors.initials: W
authors.lastname: Zhu
authors.forename: Leonardo
authors.initials: L
authors.lastname: Puppulin
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D001672:Biocompatible Materials / Q000737:chemistry; D002516:Ceramics; D004058:Diffusion; D005270:Femur Head; D017276:Friction; D006621:Hip Joint / Q000502:physiology*; D006622:Hip Prosthesis; D006801:Humans; D018613:Microscopy, Confocal; D010100:Oxygen / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D020959:Polyethylene / Q000737:chemistry*; D011474:Prosthesis Design; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D020959:Polyethylene; D010100:Oxygen