Comparison of wear of ultra-high molecular weight polyethylene acetabular cups against surface-engineered femoral heads

Abstract

Alumina ceramic heads have been previously shown to reduce polyethylene wear in comparison to cobalt chrome (CoCr) heads in artificial hip joints. However, there are concerns about the brittle nature of ceramics. It is therefore of interest to investigate ceramic-like coatings on metallic heads. The aim of this study was to compare the friction and wear of ultra-high molecular weight polyethylene (UHMWPE) against alumina ceramic, CoCr, and surface-engineered ceramic-like coatings in a friction simulator and a hip joint simulator. All femoral heads tested were 28 mm diameter and included: Biolox Forte alumina, CoCr, arc evaporative physical vapour deposition (AEPVD) chromium nitride (CrN) coated CoCr, plasma-assisted chemical vapour deposition (PACVD) amorphous diamond-like carbon (aDLC) coated CoCr, sputter CrN coated CoCr, reactive gas controlled arc (RGCA) AEPVD titanium nitride (TiN) coated CoCr, and Graphit-iC coated CoCr. These were articulated against UHMWPE acetabular cups in a friction simulator and a hip joint simulator. Alumina and CoCr gave the lowest wear volumes whereas the sputter coated CrN gave the highest. Alumina also had the lowest friction factor. There was an association between surface parameters and wear. This study indicates that surface topography of surface-engineered femoral heads is more important than friction and wettability in controlling UHMWPE wear.

Reduced Wear of Cross-linked UHMWPE Using Magnesia-stabilized Zirconia Femoral Heads in a Hip Simulator

“…Galvin et al [18] likewise reported a small increase in wear of liners bearing against DLC-coated CoCr femoral heads, relative to noncoated femoral heads. The true advantage of a DLC-Mg-PSZ femoral head might be in its resistance to abrasive wear [35].…”

“…The use of DLC coatings [14,25,33] has been proposed as a method to enhance bearing surfaces in joint replacement, but DLC-coated metal femoral heads failed in clinical use [47] and did not reduce wear in simulator tests [18]. However, the wear performance and durability of uncoated and DLC-coated Mg-PSZ femoral heads is not known.…”

“…DLC-CoCr specimens were not considered for wear tests because DLC-coated CoCr specimens reportedly exhibit poor adhesion in scratch tests [35], and previous hip simulator studies suggest DLC-coated CoCr heads produce greater gravimetric wear compared with uncoated CoCr [18] and alumina femoral heads [40]. Eleven UHMWPE acetabular liners (eight wear specimens and three soak controls) were machined from GUR 1050 that had been cross-linked to 100 kGy by gamma irradiation and remelted at 150°C for 5 hours (MediTECH 1 , Fort Wayne, IN, USA); however, they were not subsequently sterilized.…”

“…The DLC deposition process can be tailored to produce a strong amorphous film with no grain boundaries and hardness values ranging from 10 to 80 GPa [33]. However, DLCcoated titanium alloy femoral heads failed in clinical use [47], and DLC-coated CoCr femoral heads reportedly do not reduce wear compared with uncoated CoCr heads in hip simulator tests [18], but the durability and wear performance of DLC-coated ceramic materials is unknown. DLC-coated Mg-PSZ reportedly forms a stronger construct than DLC-coated CoCr [35], suggesting an improved resistance to abrasive wear.…”

Evaluation of Two Total Hip Bearing Materials for Resistance to Wear Using a Hip Simulator

“…Changes have been made to reduce wear of titanium alloy heads by modifying the surface [12,13] so that it would not be necessary to utilize cobalt heads on titanium alloy femoral stems. It has been suggested that the nature of the femoral head might affect the wear of the polyethylene so a change to ceramic heads [15][16][17][18][19][20][21][22][23][24] was tested and has been instituted in many marketed devices. The use of ceramic-on-ceramic, in which both component materials are replaced by ceramic has also been tested and utilized in surgery [25][26][27][28] for several years.…”