title: Retrieval analysis of titanium nitride (TiN) coated prosthetic femoral heads articulating with polyethylene.
abstract: Data regarding in vivo performance of titanium nitride (TiN) coated prosthetic femoral heads is scarce, and available studies of older generations of implants demonstrated coating wear in vivo. That is why we conducted a retrieval analysis of 11 femoral heads (articulating in vivo for 1-56 months) with TiN film formed using physical vapor deposition (PVD), to verify if coating failure is a problem in contemporary implants. Retrieved implants were examined using scanning electron microscope, coating roughness was evaluated with a contact profilometer and adhesion was tested using a Rockwell HRC test according to VDI 3824 guideline. Although no gross failure of the TiN coating was observed in our retrievals, all implants had defects typical for PVD coatings, such as pinholes, small titanium droplets and blisters with delaminated coating. In some heads the coating was contaminated with small niobium (Nb) droplets uniformly scattered on the entire surface of the film. Presence of Nb contamination was associated with an increased number and area of other types of defects and poorer coating adhesion. In one component, subjected to multiple dislocations we found severe delamination and cracking of the coating, increased roughness and the presence of third bodies. Our results indicate, that although wear of the coating is lower than seen in older generations of implants, inconsistent quality of the TiN film among different implants indicates the need for strict monitoring of the manufacturing process.
authors.affiliation: Department of General Orthopaedics, Musculoskeletal Oncology and Trauma Surgery, Poznan University of Medical Sciences, Poznań, Poland. Electronic address: alefazajapierdole@tlen.pl.
authors.forename: Łukasz
authors.initials: Ł
authors.lastname: Łapaj
authors.affiliation: Metal Examining Division, Metal Forming Institute, Poznań, Poland.
authors.forename: Justyna
authors.initials: J
authors.lastname: Wendland
authors.affiliation: Department of General Orthopaedics, Musculoskeletal Oncology and Trauma Surgery, Poznan University of Medical Sciences, Poznań, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Markuszewski
authors.affiliation: Surface Engineering and Tribology Laboratory, Metal Forming Institute, Poznań, Poland.
authors.forename: Adrian
authors.initials: A
authors.lastname: Mróz
authors.affiliation: Surface Engineering and Tribology Laboratory, Metal Forming Institute, Poznań, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Wiśniewski
mesh_terms: D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D005270:Femur Head; D006622:Hip Prosthesis; D008422:Materials Testing; D055595:Mechanical Phenomena; D020959:Polyethylene / Q000737:chemistry*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014835:Volatilization
chemical_list: D020099:Coated Materials, Biocompatible; C041500:titanium nitride; D020959:Polyethylene; D014025:Titanium
keywords: Coating wear; Orthopedic implant coating; Titanium nitride; Total hip arthroplasty