No abstract

No abstract

No abstract

The use of modular interlocking components is a central design feature of total joint replacements. In this investigation we hypothesized that clinically available ceramic-metal modular connections used in total hip arthroplasty release more metal through fretting corrosion than traditional metal-metal modular connections. This was investigated using an in vitro comparison of ceramic (zirconia, Z r 0 2 ) and metal (Co-alloy) femoral-head fretting upon Co-alloy stem components. In vitro fretting corrosion testing consisted of potentiodynamic monitoring and analysis of metal release from zirconia and Co-alloy 28 mm femoral heads with similar surface roughnesses (Ra = 0.46 p n ) on identical Co-alloy stems at 2.2 kN for 1 x 10' cycles at 2 Hz. In contrast to our original hypothesis, we found greater metal release (approximately I 1-fold increase in Co and Mold increase in Cr) and potentiodynamic fretting of metal-metal modular junctions when compared to ceramic-metal. Potentiodynamic testing demonstrated that lower initial voltages (-266 < 153 mV), greater maximum voltage changes ( I 16 > 56 mV, p < 0.05, t-test) and voltage variability (3 > 0.5 mV, p < 0.05, t-test) were associated with the open circuit potentials of Co-alloy on Co-alloy junctions when compared to zirconia on Co-alloy junctions. In this study of a single total hip replacement stem and head design, zirconia heads mated with Co-alloy stems produced less fretting than Co-alloy heads mated with Co-alloy stems. Although further studies are necessary with a variety of implant designs and under different experimental conditions, the evidence presented here should, in part, alleviate concerns of increases in fretting corrosion at modular junctions of ceramic-metal coupled components.

No abstract

No abstract

No abstract

For these patients, serum cobalt and chromium ion levels were not acutely affected by patient activity. Periodic measurements of serum ion levels could be used to monitor the tribologic (lubrication, friction, and wear) performance of a metal-on-metal bearing without adjusting for patient activity. Additional research is needed into the kinetics of ion production, transport, and excretion.