Residual Al₂O₃ From Grit Blasted Components Operate as Third Body Wear Particles in Total Knee Arthroplasty: An...

Despite the success of total knee arthroplasty (TKA), a small percentage of devices fail. Due to the high volume of surgeries performed each year, revision total knee arthroplasty surgery presents a burden on patients and surgeons. One aspect that may improve TKA outcomes is device design, specifically the use of grit blasting to increase the surface roughness. This is a common design feature seen in TKA where grit blasted instruments and implants such as the tibial tray will be utilized during the surgery. Other components in the implant system include a polyethylene tibial insert, patellar component, and a polished femoral component. Grit blasting is a process that propels alumina grit at a high velocity to plastically deform the surface. Often, residual alumina remains embedded in the surface of the implant. In this exploratory study we evaluated the amount of alumina found on 21 explanted CoCrMo femoral components paired with 21 CoCrMo grit blasted tibial components. We asked (1) what are the potential sources of alumina in the implant system, (2) what mechanisms may be causing the potential migration of alumina to the femoral component, and (3) is the amount of alumina contamination on the CoCrMo femoral component clinically relevant? Using optical microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) we evaluated the surfaces of the explants. In SEM images taken at 500× magnification, we saw that an approximate area fraction of 34% ± 9% of the tibial components' surface was embedded with residual alumina from the grit blasting process. Alumina debris identified as third body wear particles were seen on the bearing surface of 17/21 (81%) of the femoral components. We found alumina on the posterior condyles of 13/21 (62%) of the implants. Finally, we saw large amounts of imparted alumina on devices where the polyethylene had worn and the tibial components were suspected to have made direct contact with the CoCrMo femoral components. Our results suggest that residual alumina from the grit blasting process may result in alumina third body wear particles being released onto the bearing surface of retrieved knee implants.