Background
Metal debris and ion release has raised concerns in joint arthroplasty. The purpose of this study was to characterize the sources of metallic ions and particulate debris released from long-term (in vivo > 15y) TKA femoral components.
Methods
A total of 52 CoCr femoral condyles were identified as having been implanted for more than 15 years. The femoral components were examined for incidence of five types of damage (metal-on-metal wear due to historical polyethylene insert failure, MACC at taper interfaces, cement interface corrosion, third-body abrasive wear, and ICIC). Third-body abrasive wear was evaluated using the Hood method for polyethylene components and a similar method quantifying surface damage of the femoral condyle was used. The total area damaged by ICIC was quantified using digital photogrammetry.
Results
Surface damage associated with corrosion and/or CoCr debris release was identified in 98% (n=51) of the CoCr femoral components. Five types of damage were identified: 98% of femoral components exhibited 3rd body abrasive wear (mostly observed as scratching, n=51/52), 29% of femoral components exhibited ICIC damage (n=15/52), 41% exhibited cement interface damage (n=11/27), 17% exhibited metal-on-metal wear following wear-through of the polyethylene insert (n=9/52), and 50% of the modular femoral components exhibited MACC taper damage (n=2/4). The total ICIC damaged area was an average of 0.11 ± 0.12 mm2 (Range: 0.01–0.46mm2).
Conclusion
Although implant damage in TKA is typically reported with regard to the polyethylene insert, the results of this study demonstrate that abrasive and corrosive damage occurs on the CoCr femoral condyle in vivo.