Do cement pockets prevent fluid contamination of the undersurface of tibial baseplates?

Background: Aseptic loosening remains one of the most frequent causes of implant failure following primary total knee arthroplasty (TKA). Prior literature has established that these failures appear to occur at the implant-cement interface—likely secondary to lipid contamination. Implant manufacturers have incorporated cement pockets on the undersurface of tibial implants to improve fixation. Aim: The study aimed to determine if cement pockets prevent lipid contamination of the implant-cement interface. Methods: A contemporary total knee tibial baseplate has recently incorporated cement pockets on its implants. We modeled clear acrylic tibial baseplate molds of this implant with and without cementation pockets. We then simulated an experimental cementing process with the introduction of lipids at the implant-cement interface. The surface area contamination at this interface was quantified using ImageJ software and presented as a percentage of the total baseplate surface area available for fixation. Results: For the predecessor implant design without cementation pockets, the average tibial baseplate lipid contamination was 42.82%. The average tibial baseplate lipid contamination was 30.36% for the contemporary implant design with cementation pockets. The addition of cement pockets was found to significantly reduce lipid contamination (p = 0.0265). Conclusion: Lipid contamination of the implant-cement interface remains a primary mechanism of implant failure following primary TKA. We found that the addition of cement pockets decreased the surface area of implant contamination with fluid. Therefore, while it is unclear whether cement pockets improve implant fixation, they do appear to reduce fluid/lipid contamination and alternative undersurface geometries and techniques should be considered to help prevent lipid contamination. Relevance for Patients: Cement pockets and other undersurface designs may help prevent aseptic loosening, which has become a leading cause of revision surgery for persistently painful and/or unstable TKA in patients.