Colton, CA, United States
Colton, CA, United States

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Halim T.,Donaldson Arthritis Research Foundation | Burgett M.,Donaldson Arthritis Research Foundation | Donaldson T.K.,Donaldson Arthritis Research Foundation | Savisaar C.,U.S. Food and Drug Administration | And 3 more authors.
Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine | Year: 2014

Particles of bone cement (polymethyl methacrylate), CoCr and Ti6Al4V were compared for their abrasion potential against CoCr substrates. This appears to be the first study utilizing CoCr and Ti6Al4V particulates to abrade CoCr bearings and the first study profiling the morphology of third-body abrasive wear scratches in a hip simulator. The 5 mg debris allotments (median size range 140-300 μm) were added to cups mounted both inverted and anatomically with metal-on-metal (MOM) bearings in a 10-cycle, hip simulator test. Surface abrasion was characterized by roughness indices and scratch profiles. Compared to third-body abrasion with metal debris, polymethyl methacrylate debris had minimal effect on the CoCr surfaces. In all, 10 cycles of abrasion with metal debris demonstrated that roughness indices (Ra, PV) increased approximately 20-fold from the unworn condition. The scratch profiles ranged 20-108 μm wide and 0.5-2.8 μm deep. The scratch aspect ratio (W/PV) averaged 0.03, and this very low ratio indicated that the 140 μm CoCr beads had plastically deformed to create wide but shallow scratches. There was no evidence of transfer of CoCr beads to CoCr bearings. The Ti64 particles produced similar scratch morphology with the same aspect ratio as the CoCr particulates. However, the titanium particulates also showed a unique ability to flatten and adhere to the CoCr, forming smears and islands of contaminating metal on the CoCr bearings. The morphology of scratches and metal transfer produced by these large metal particulates in the simulator appeared identical to those reported on retrieved metal-on-metal bearings. © IMechE 2014.

Pelt C.E.,University of Utah | Erickson J.,University of Utah | Clarke I.,Loma Linda University | Donaldson T.,Donaldson Arthritis Research Foundation | And 2 more authors.
Journal of Bone and Joint Surgery - Series A | Year: 2013

Despite multiple changes in second-generation metal-on-metal hip implants, greater-than-expected revision rates have led to alarm. We hypothesized that the finding of intraoperative metallosis would be associated with a high metal load on histologic analysis and that both would be associated with increased wear, greater serum metal ion levels, and predictable biologic responses in the histologic sections.We evaluated the implant positioning, serum ion levels, intraoperative findings of metallosis, wear characteristics of retrieved implants (tribology), histology, and outcomes in a series of eighteen large-diameter metal-on-metal total hip arthroplasties. The arthroplasties were divided into two groups on the basis of the intraoperative finding of metallosis and into two groups on the basis of the metal load score. Intraoperative metallosis was not associated with a high metal load score (p = 0.15). The finding of intraoperative metallosis was associated with greater serum metal ion levels, greater wear rates, and greater complication rates. Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) scores were similar between the metallosis and non-metallosis groups (p = 0.49) as well as between the high and low-metal-load groups (p = 0.56). Copyright © 2013 by The Journal of Bone and Joint Surgery, Incorporated.

Burgett M.,Donaldson Arthritis Research Foundation | Donaldson T.,Donaldson Arthritis Research Foundation | Clarke C.,Donaldson Arthritis Research Foundation | Savisaar C.,CDHA | Bowsher J.,CDHA
ASTM Special Technical Publication | Year: 2013

Simulator and explant studies have noted contamination of pro-tein films on hip bearings. These films have been suggested to play a role in lubrication and wear mechanisms as both (i) a tribolayer and (ii) a confounding contaminant. It has been suggested that these films composed of protein might be responsible for cyclic weight fluctuations (0.2 to 2mg) that can obscure gravimetric wear measurements. The aim of this work was to study protein films on simulator and explant hip bearings and develop a method for removing these protein films. Four types of bearings from simulators and explants (metal-on-metal [M-M], ceramic-on-ceramic [C-C], metal-on-poly- ethylene [M-PE], and ceramic-on-polyethylene [C-PE]) were examined for protein films. The topographies of protein films were characterized via interferometry and scanning electron microscopy. C-C bearings were washed with both acid and chemical solutions and M-M bearings were washed only with chemical solution and the topographies were analyzed. All bearing types were contaminated with protein films. The films were characterized as a thin adsorbed monolayer and clustered gelatinous "islands" predominantly located along the edge of the main wear zone. They were confirmed by their characteristic roughness and third-body wear tracks transitioning through the raised islands. Acid wash treatment on ceramics revealed a weight loss of up to 2 mg, whereas the chemical wash treatment yielded a weight loss that was 10 times less. The chemical wash successfully removed 1.8mg of protein from the M-M simulator bearings. The accumulation of protein varied, with M- M and C-CM-PE and C-PE. The protein film topography on explanted bearings confirmed that protein films occur in vivo. The weight loss achieved through the wash treatments confirmed the removal of protein layers. Copyright © 2013 by ASTM International.

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