Third-body wear of cobalt-chromium-molybdenum implant alloys initiated by bone and poly(methyl methacrylate) particles

Abstract

The potential for bone and poly(methyl methacrylate) (PMMA) debris to initiate wear on ASTM-F75 and ASTM-F799 CoCrMo alloys articulating against ultrahigh molecular weight polyethylene (UHMWPE) was investigated. Third-body wear particles of bone and PMMA bone cement (with and without the radiopacifier, barium sulfate) were introduced between CoCrMo and UHMWPE in a reciprocating sliding wear test. A scanning electron microscope and a white light interference surface profilometer were used to study the surface damage and quantify the surface roughnesses of the worn alloys. The CoCrMo alloys, which are widely used as the femoral components in total artificial knees and hips, showed surface damage as the result of wear in the presence of bone or PMMA debris. Severe scratches were generated within 2700 cycles (94.5-m sliding distance) on the alloy's surface. Ploughing was the major wear mechanism. Carbides in the F75 alloy surface appeared to be unaffected by the debris. A quantitative study was performed on the surface roughness (average roughness, R(a), and root mean square roughness, RMS) of the alloy after wear testing. A nonparametric Wilcoxon rank sum test of wear severity (R(a) and RMS) was performed based on the surface roughness data. The surfaces of the specimens tested with the PMMA and bone particles were significantly rougher than those of the controls (p < 0.01). Small scratches also occurred on some of the control specimen surfaces and may have been second-body wear caused by defects and impurities in the UHMWPE.

Effects of episodic subluxation events on third body ingress and embedment in the THA bearing surface

“…Multidirectional scratching of the femoral heads, similar to that in the present specimens, was observed. Que and Topoleski (2000) found that particles of polymerized bone cement (both with and without barium sulfate) or of bone, when added to the lubricant fluid, scratched CoCrMo specimens articulating in a pin-on-disc test against UHMWPE, with severe scratches on the metal being observed with as few as 2700 cycles. Davidson et al (1994) increased the wear of a UHMWPE pin articulating on CoCrMo by adding titanium particles to the lubricant fluid, with the amount of wear increasing with particle concentration, provided that a threshold concentration was achieved.…”

“…Metallic debris predominates as third body particles, as demonstrated by a retrieval study of polyethylene liners involving quantification of embedded particles (Lundberg et al, 2007a); examples of metallic third body particles include porous ingrowth beads (Dowd et al, 2000;Najjar et al, 2000) or metal particles from the implants (Hirakawa et al, 2004;Huk et al, 1994;Kim et al, 2005;Lewis, 1997), from trochanteric reattachment fixation (Amstutz and Maki, 1978;Bronson, 1976;Hop et al, 1997), or from surgical instruments (Mackay et al, 2000). Third body particles can also originate from hydroxyapatite (Bauer et al, 1994;Bloebaum et al, 1997;Willie et al, 2000), bone (Que and Topoleski, 2000), or bone cement (Isaac et al, 1992;Joshi et al, 2001). Once they gain access to the space between the articulating components, third bodies can directly abrade both the acetabular and femoral head bearing surfaces.…”

“…Although no broadly accepted testing standards yet exist for simulating third body wear, both hip simulator (Bragdon et al, 2003) and pin-on-disc (Davidson et al, 1994;McKellop et al, 1981;Que and Topoleski, 2000) tests of UHMWPE against metal have demonstrated that scratching of the metal surface and dramatically increased polyethylene wear can occur after the introduction of third body particles into the lubricant fluid. Other protocols have placed third body particles directly in the articulating surface (Davidson et al, 1994;McKellop et al, 1981;McKellop and Rostlund, 1990;McNie et al, 2000), or have indirectly simulated third body effects using abrasion-tumbling, emery abrasion, or discrete scratching of femoral heads (Affatato et al, 2005;Barbour et al, 2000;Endo et al, 2001;McKellop et al, 1999;Wang et al, 1998); many of these studies also demonstrated increased polyethylene wear resulting from third body effects.…”

Mechanism of Chromium Oxide Formation in Cobalt–Chromium–Molybdenum (F75) Alloys Prepared Using Spark Plasma Sintering

“…The carbides are known to cause accelerated wear, as they become dislodged between the bearing surfaces causing third body wear. [35] Chromium oxide coatings on these alloys have been investigated to increase the wear resistance and due to its high hardness have shown lower wear rates compared to other coating materials currently used. [36] This produces less wear debris, reduces the amount of osteolysis occurring, and improves the life span of the implant.…”

Protective coatings on medical implants by reactive diffusion

“…From materials or combinations of materials used currently metal-on-UHMWPE (ultra high molecular weight polyethylene) bearings result in relative large volumetric wear [1][2][3], ceramics such as alumina [4][5][6] have an excellent wear resistance but are brittle, that may cause fracture during accidents, metal-on-metal bearings (usually CoCrMo alloys) [7][8][9] have good wear resistance, but release nanometric debris and ions that may cause allergy or have toxic effects. The desired alternative combination should posses the high fracture toughness of metals and the wear performance of ceramics.…”